Sample records for slope ratio method
 «
 1
 2
 3
 4
 5
 »

Combined slope ratio analysis and linearsubtraction: An extension of the Pearce ratio method
NASA Astrophysics Data System (ADS)
De Waal, Sybrand A.
19960701
A new technique, called combined slope ratio analysis, has been developed by extending the Pearce element ratio or conserveddenominator method (Pearce, 1968) to its logical conclusions. If two stoichiometric substances are mixed and certain chemical components are uniquely contained in either one of the two mixing substances, then by treating these unique components as conserved, the composition of the substance not containing the relevant component can be accurately calculated within the limits allowed by analytical and geological error. The calculated composition can then be subjected to rigorous statistical testing using the linearsubtraction method recently advanced by Woronow (1994). Application of combined slope ratio analysis to the rocks of the Uwekahuna Laccolith, Hawaii, USA, and the lavas of the 1959summit eruption of Kilauea Volcano, Hawaii, USA, yields results that are consistent with field observations.

The QSlope Method for Rock Slope Engineering
NASA Astrophysics Data System (ADS)
Bar, Neil; Barton, Nick
20171201
Qslope is an empirical rock slope engineering method for assessing the stability of excavated rock slopes in the field. Intended for use in reinforcementfree road or railway cuttings or in opencast mines, Qslope allows geotechnical engineers to make potential adjustments to slope angles as rock mass conditions become apparent during construction. Through case studies across Asia, Australia, Central America, and Europe, a simple correlation between Qslope and longterm stable slopes was established. Qslope is designed such that it suggests stable, maintenancefree benchface slope angles of, for instance, 40°45°, 60°65°, and 80°85° with respective Qslope values of approximately 0.1, 1.0, and 10. Qslope was developed by supplementing the Qsystem which has been extensively used for characterizing rock exposures, drillcore, and tunnels under construction for the last 40 years. The Q' parameters (RQD, J n, J a, and J r) remain unchanged in Qslope. However, a new method for applying J r/ J a ratios to both sides of potential wedges is used, with relative orientation weightings for each side. The term J w, which is now termed J wice, takes into account longterm exposure to various climatic and environmental conditions such as intense erosive rainfall and icewedging effects. Sloperelevant SRF categories for slope surface conditions, stressstrength ratios, and major discontinuities such as faults, weakness zones, or joint swarms have also been incorporated. This paper discusses the applicability of the Qslope method to slopes ranging from less than 5 m to more than 250 m in height in both civil and mining engineering projects.

Performance of the Bowen ratio systems on a 22 deg slope
NASA Technical Reports Server (NTRS)
Nie, D.; Flitcroft, I.; Kanemasu, E. T.
19900101
The Bowen ratio energy balance technique was used to assess the energy fluxes on inclined surfaces during the First ISLSCP Field Experiment (FIFE). Since air flow over sloping surface may differ from that over flat terrain, it is important to examine whether Bowen ratio measurements taken on sloping surfaces are valid. In this study, the suitability of using the Bowen ratio technique on sloping surfaces was tested by examining the assumptions that the technique requires for valid measurements. This was accomplished by studying the variation of Bowen ratio measurements along a selected slope at the FIFE site. In September 1988, four Bowen ratio systems were set up in a line along the 22 degree northfacing slope with northerly air flow (wind went up the slope). In July of 1989, six Bowen ratio systems were similarly installed with southerly air flow (the wind went down slope). Results indicated that, at distances between 10 to 40 meters from the top of the slope, no temperature or vapor pressure gradient parallel to the slope was detected. Uniform Bowen ratio values were obtained on the slope, and thus the sensible or latent heat flux should be similar along the slope. This indicates that the assumptions for valid flux measurements are reasonably met at the slope. The Bowen ratio technique should give the best estimates of the energy fluxes on slopes similar to that in this study.

The study on length and diameter ratio of nail as preliminary design for slope stabilization
NASA Astrophysics Data System (ADS)
Gunawan, Indra; Silmi Surjandari, Niken; Muslih Purwana, Yusep
20171101
Soil nailing technology has been widely applied in practice for reinforced slope. The number of studies for the effective design of nailreinforced slopes has also increased. However, most of the previous study was focused on a safety factor of the slope; the ratio of length and diameter itself has likely never been studied before. The aim of this study is to relate the length and diameter ratio of the nail with the safety factor of the 20 m height of sand slope in the various angle of friction and steepness of the slope. Simplified Bishop method was utilized to analyze the safety factor of the slope. This study is using data simulation to calculate the safety factor of the slope with soil nailing reinforcement. The results indicate that safety factor of slope stability increases with the increase of length and diameter ratio of the nail. At any angle of friction and steepness of the slope, certain effective length and diameter ratio was obtain. These results may be considered as a preliminary design for slope stabilization.

Slope stability and bearing capacity of landfills and simple onsite test methods.
Yamawaki, Atsushi; Doi, Yoichi; Omine, Kiyoshi
20170701
This study discusses strength characteristics (slope stability, bearing capacity, etc.) of waste landfills through onsite tests that were carried out at 29 locations in 19 sites in Japan and three other countries, and proposes simple methods to test and assess the mechanical strength of landfills on site. Also, the possibility of using a landfill site was investigated by a fullscale eccentric loading test. As a result of this, landfills containing more than about 10 cm long plastics or other fibrous materials were found to be resilient and hard to yield. An onsite full scale test proved that no differential settlement occurs. The repose angle test proposed as a simple onsite test method has been confirmed to be a good indicator for slope stability assessment. The repose angle test suggested that landfills which have high, nearsaturation water content have considerably poorer slope stability. The results of our repose angle test and the impact acceleration test were related to the internal friction angle and the cohesion, respectively. In addition to this, it was found that the air pore volume ratio measured by an onsite air pore volume ratio test is likely to be related to various strength parameters.

Evaluation of Thermoelectric Devices by the SlopeEfficiency Method
20160901
ARLTR7837 ● SEP 2016 US Army Research Laboratory Evaluation of Thermoelectric Devices by the SlopeEfficiency Method by...Evaluation of Thermoelectric Devices by the SlopeEfficiency Method by Patrick J Taylor Sensors and Electron Devices Directorate, ARL Jay R...

Analysis of slope stabilization by soil bioengineering method
NASA Astrophysics Data System (ADS)
Switala, Barbara Maria; Wu, Wei
20130401
The aim of the project is to create a numerical model which will include the impact of vegetation on the slope stability analysis, considering both mechanical and hydrological factors. This will enrich the current knowledge about how roots reinforce the soil layers on the slope and how it influences the increase of shear strength of the soil. This has to be combined together with hydrological effects caused by evapotranspiration: modified soil moisture regime, dissipation of excess pore pressure and established matric suction. Coupled analyses (mechanical and hydrological) are rarely conducted, or only outdated models are used, which leads to overestimation of the additional shear strength of soil. That is why there is a need to support this branch of landslide hazard assessment and develop a new model. This research will help to raise awareness, that soil bioengineering methods of slope stabilization can in some cases be more appropriate and less expensive than traditional methods. As an input to the model, the appropriate slope geometry and soil properties have to be chosen. It is also important to consider different plant types and root properties, as well as different levels of groundwater table. To assess the effect of evapotranspiration it is necessary to know the geographical location of the slope and the weather conditions in the chosen region. The final output of the model, which will help to quantitatively assess the impact of vegetation on the slope stability, is the factor of safety (FOS) for vegetated slope for different types of soil and degrees of saturation. Results may then be compared with different conditions and factors of safety, calculated for the corresponding nonvegetated slope. It will be possible to specify the most favorable and unfavorable conditions. Moreover, the calculations provide also information on changes of cohesion, caused by mechanical and hydrological effects, as well as the change in the friction angle of soil.

NASA Astrophysics Data System (ADS)
Sulpizio, R.; Castioni, D.; RodriguezSedano, L. A.; Sarocchi, D.; Lucchi, F.
20161101
Laboratory experiments on granular flows using natural material were carried out in order to investigate the behaviour of granular flows passing over a break in slope. Sensors in the depositional area recorded the flow kinematics, while video footage permitted reconstruction of the deposit formation, which allowed investigation of the deposit shape as a function of the change in slope. We defined the slopeangle ratio as the proportion between slope angle in the depositional area and that of the channel. When the granular flow encounters the break in slope part of the flow front forms a bouncing clast zone due to elastic impact with the expansion box floor. During this process, part of the kinetic energy of the dense granular flow is transferred to elutriating fine ash, which subsequently forms turbulent ash cloud accompanying the granular flow until it comes to rest. Morphometric analysis of the deposits shows that they are all elliptical, with an almost constant minor axis and a variable major axis. The almost constant value of the minor axis relates to the spreading angle of flow at the end of the channel, which resembles the basal friction angle of the material. The variation of the major axis is interpreted to relate to the effect of competing inertial and frictional forces. This effect also reflects the partitioning of centripetal and tangential velocities, which changes as the flow passes over the break in slope. After normalization, morphometric data provided empirical relationships that highlight the dependence of runout from the product of slopeangle ratio and the difference in height between granular material release and deposit. The empirical relationships were tested against the runouts of hot avalanches formed during the 1944 ad eruption at Vesuvius, with differences among actual and calculated values are between 1.7 and 15 %. Velocity measurements of laboratory granular flows record deceleration paths at different breaks in slope. When normalized

A method for determining average beach slope and beach slope variability for U.S. sandy coastlines
Doran, Kara S.; Long, Joseph W.; Overbeck, Jacquelyn R.
20150101
The U.S. Geological Survey (USGS) National Assessment of HurricaneInduced Coastal Erosion Hazards compares measurements of beach morphology with storminduced total water levels to produce forecasts of coastal change for storms impacting the Gulf of Mexico and Atlantic coastlines of the United States. The waveinduced water level component (wave setup and swash) is estimated by using modeled offshore wave height and period and measured beach slope (from dune toe to shoreline) through the empirical parameterization of Stockdon and others (2006). Spatial and temporal variability in beach slope leads to corresponding variability in predicted wave setup and swash. For instance, seasonal and storminduced changes in beach slope can lead to differences on the order of 1 meter (m) in waveinduced water level elevation, making accurate specification of this parameter and its associated uncertainty essential to skillful forecasts of coastal change. A method for calculating spatially and temporally averaged beach slopes is presented here along with a method for determining total uncertainty for each 200m alongshore section of coastline.

Determination of slope failure using 2D resistivity method
NASA Astrophysics Data System (ADS)
Muztaza, Nordiana Mohd; Saad, Rosli; Ismail, Nur Azwin; Bery, Andy Anderson
20170701
Landslides and slope failure may give negative economic effects including the cost to repair structures, loss of property value and medical costs in the event of injury. To avoid landslide, slope failure and disturbance of the ecosystem, good and detailed planning must be done when developing hilly area. Slope failure classification and various factors contributing to the instability using 2D resistivity survey conducted in Selangor, Malaysia are described. The study on landslide and slope failure was conducted at Site A and Site B, Selangor using 2D resistivity method. The implications of the anticipated ground conditions as well as the field observation of the actual conditions are discussed. Nine 2D resistivity survey lines were conducted in Site A and six 2D resistivity survey lines with 5 m minimum electrode spacing using Poledipole array were performed in Site B. The data were processed using Res2Dinv and Surfer10 software to evaluate the subsurface characteristics. 2D resistivity results from both locations show that the study areas consist of two main zones. The first zone is alluvium or highly weathered with the resistivity of 1001000 Ωm at 2070 m depth. This zone consists of saturated area (1100 Ωm) and boulders with resistivity value of 12003000 Ωm. The second zone with resistivity values of > 3000 Ωm was interpreted as granitic bedrock. The study area was characterized by saturated zones, highly weathered zone, highly contain of sand and boulders that will trigger slope failure in the survey area. Based on the results obtained from the study findings, it can be concluded that 2D resistivity method is useful method in determination of slope failure.

Slope stability analysis using limit equilibrium method in nonlinear criterion.
Lin, Hang; Zhong, Wenwen; Xiong, Wei; Tang, Wenyu
20140101
In slope stability analysis, the limit equilibrium method is usually used to calculate the safety factor of slope based on MohrCoulomb criterion. However, MohrCoulomb criterion is restricted to the description of rock mass. To overcome its shortcomings, this paper combined HoekBrown criterion and limit equilibrium method and proposed an equation for calculating the safety factor of slope with limit equilibrium method in HoekBrown criterion through equivalent cohesive strength and the friction angle. Moreover, this paper investigates the impact of HoekBrown parameters on the safety factor of slope, which reveals that there is linear relation between equivalent cohesive strength and weakening factor D. However, there are nonlinear relations between equivalent cohesive strength and Geological Strength Index (GSI), the uniaxial compressive strength of intact rock σ ci , and the parameter of intact rock m i . There is nonlinear relation between the friction angle and all HoekBrown parameters. With the increase of D, the safety factor of slope F decreases linearly; with the increase of GSI, F increases nonlinearly; when σ ci is relatively small, the relation between F and σ ci is nonlinear, but when σ ci is relatively large, the relation is linear; with the increase of m i , F decreases first and then increases.

Slope Stability Analysis Using Limit Equilibrium Method in Nonlinear Criterion
Lin, Hang; Zhong, Wenwen; Xiong, Wei; Tang, Wenyu
20140101
In slope stability analysis, the limit equilibrium method is usually used to calculate the safety factor of slope based on MohrCoulomb criterion. However, MohrCoulomb criterion is restricted to the description of rock mass. To overcome its shortcomings, this paper combined HoekBrown criterion and limit equilibrium method and proposed an equation for calculating the safety factor of slope with limit equilibrium method in HoekBrown criterion through equivalent cohesive strength and the friction angle. Moreover, this paper investigates the impact of HoekBrown parameters on the safety factor of slope, which reveals that there is linear relation between equivalent cohesive strength and weakening factor D. However, there are nonlinear relations between equivalent cohesive strength and Geological Strength Index (GSI), the uniaxial compressive strength of intact rock σ ci, and the parameter of intact rock m i. There is nonlinear relation between the friction angle and all HoekBrown parameters. With the increase of D, the safety factor of slope F decreases linearly; with the increase of GSI, F increases nonlinearly; when σ ci is relatively small, the relation between F and σ ci is nonlinear, but when σ ci is relatively large, the relation is linear; with the increase of m i, F decreases first and then increases. PMID:25147838

Araujo, Beatriz Ferreira; Hintelmann, Holger; Dimock, Brian; Almeida, Marcelo Gomes; Rezende, Carlos Eduardo
20170701
Mercury (Hg) may originate from both anthropogenic and natural sources. The measurement of spatial and temporal variations of Hg isotope ratios in sediments may enable source identification and tracking of environmental processes. In this study we establish the distribution of mercury concentrations and mercury isotope ratios in surface sediments of three transects along the continental shelf and slope in Campos BasinRJBrazil. The shelf showed on average lower total Hg concentrations (9.2±5.3ngg 1 ) than the slope (24.6±8.8ngg 1 ). MMHg average concentrations of shelf 0.15±0.12ngg 1 and slope 0.13±0.06ngg 1 were not significantly different. Distinct differences in Hg isotope ratio signatures were observed, suggesting that the two regions were impacted by different sources of Hg. The shelf showed more negative δ 202 Hg and Δ 199 Hg values ranging from0.59 to2.19‰ and from0.76 to 0.08‰, respectively. In contrast, the slope exhibited δ 202 Hg values from0.29 to1.82‰ and Δ 199 Hg values from0.23 to 0.09‰. Mercury found on the shelf, especially along the "D" and "I" transects, is depleted in heavy isotopes resulting in more negative δ 202 Hg compared to the slope. Isotope ratios observed in the "D" and "I" shelf region are similar to Hg ratios commonly associated with plants and vegetation and very comparable to those detected in the estuary and adjoining mangrove forest, which suggests that Hg exported from rivers may be the dominating source of Hg in near coastal regions along the northern part of the shelf. Copyright © 2017 Elsevier Ltd. All rights reserved.

NASA Astrophysics Data System (ADS)
Chae, B.G.; Lee, J.H.; Park, H.J.; Choi, J.
20150801
Most landslides in Korea are classified as shallow landslides with an average depth of less than 2 m. These shallow landslides are associated with the advance of a wetting front in the unsaturated soil due to rainfall infiltration, which results in an increase in water content and a reduction in the matric suction in the soil. Therefore, this study presents a modified equation of infinite slope stability analysis based on the concept of the saturation depth ratio to analyze the slope stability change associated with the rainfall on a slope. A rainfall infiltration test in unsaturated soil was performed using a column to develop an understanding of the effect of the saturation depth ratio following rainfall infiltration. The results indicated that the rainfall infiltration velocity due to the increase in rainfall in the soil layer was faster when the rainfall intensity increased. In addition, the rainfall infiltration velocity tends to decrease with increases in the unit weight of soil. The proposed model was applied to assess its feasibility and to develop a regional landslide susceptibility map using a geographic information system (GIS). For that purpose, spatial databases for input parameters were constructed and landslide locations were obtained. In order to validate the proposed approach, the results of the proposed approach were compared with the landslide inventory using a ROC (receiver operating characteristics) graph. In addition, the results of the proposed approach were compared with the previous approach used: a steadystate hydrological model. Consequently, the approach proposed in this study displayed satisfactory performance in classifying landslide susceptibility and showed better performance than the steadystate approach.

Slope angle estimation method based on sparse subspace clustering for probe safe landing
NASA Astrophysics Data System (ADS)
Li, Haibo; Cao, Yunfeng; Ding, Meng; Zhuang, Likui
20180601
To avoid planetary probes landing on steep slopes where they may slip or tip over, a new method of slope angle estimation based on sparse subspace clustering is proposed to improve accuracy. First, a coordinate system is defined and established to describe the measured data of light detection and ranging (LIDAR). Second, this data is processed and expressed with a sparse representation. Third, on this basis, the data is made to cluster to determine which subspace it belongs to. Fourth, eliminating outliers in subspace, the correct data points are used for the fitting planes. Finally, the vectors normal to the planes are obtained using the plane model, and the angle between the normal vectors is obtained through calculation. Based on the geometric relationship, this angle is equal in value to the slope angle. The proposed method was tested in a series of experiments. The experimental results show that this method can effectively estimate the slope angle, can overcome the influence of noise and obtain an exact slope angle. Compared with other methods, this method can minimize the measuring errors and further improve the estimation accuracy of the slope angle.

A Study on Project Priority Evaluation Method on Road Slope Disaster Prevention Management
NASA Astrophysics Data System (ADS)
Sekiguchi, Nobuyasu; Ohtsu, Hiroyasu; Izu, Ryuutarou
To improve the safety and security of driving while coping with today's stagnant economy and frequent natural disasters, road slopes should be appropriately managed. To achieve the goals, road managers should establish project priority evaluation methods for each stage of road slope management by clarifying social losses that would result by drops in service levels. It is important that road managers evaluate a project priority properly to manage the road slope effectively. From this viewpoint, this study proposed "project priority evaluation methods" in road slope disaster prevention, which use available slope information at each stage of road slope management under limited funds. In addition, this study investigated the effect of managing it from the high slope of the priority by evaluating a risk of slope failure. In terms of the amount of available information, staged information provision is needed ranging from macroscopic studies, which involves evaluation of the entire route at each stage of decision making, to semi and microscopic investigations for evaluating slopes, and microscopic investigations for evaluating individual slopes. With limited funds, additional detailed surveys are difficult to perform. It is effective to use the slope risk assessment system, which was constructed to complement detailed data, to extract sites to perform precise investigations.

C:N:P Molar Ratios, Sources and 14C Dating of Surficial Sediments from the NW Slope of Cuba.
de la Lanza Espino, Guadalupe; Soto, Luis A
20150101
The surficial sediments recovered from 12 sites located near the channel axis of the Florida Straits and the lower slope off NW Cuba were analyzed for total organic carbon (TOC), nitrogen (TN), phosphorus (TP), elemental C:N:P ratios, C and N isotopic values, and 14C dating. The depth profiles of TOC, TN, and TP (018 cm) displayed a downcore trend and a significant variation. The TOC values were low (0.15 to 0.62%; 66 to 516 µmol g(1)). Sites near the island's lower slope had lower TOC average concentrations (158333 µmol g(1)) than those closer to the channel axis (averaging 341516 µmol g(1); p <0.05). The TN concentrations near the lower slope attained 0.11% (80 µmol g(1)), whereas, towards the channel axis, they decreased to 0.07% (55 µmol g(1); p<0.05). The C:N ratios ranged from 1.9 to 10.2. The mean molar C:N ratio (5.4) indicated a marine hemipelagic deposition. The TP was lower at sites near the lower slope (38.4 to 50.0 µmol gv; 0.12% to 0.16%) than those near the channel axis (50.0 to 66 µmol g(1); 0.15 to 0.21%). C:P fluctuated from 7.7 to 14.1 in the surficial sediment layer. The bulk organic δ13Corg and δ15N values confirmed pelagic organic sources, and the 14C dating revealed that the sediments were deposited during the Holocene (10005000 yr BP). We suggest that the hydrodynamic conditions in the Straits influence vertical and advective fluxes of particulate organic material trapped in the mixedlayer, which reduces the particulate matter flux to the seabed.

C:N:P Molar Ratios, Sources and 14C Dating of Surficial Sediments from the NW Slope of Cuba
de la Lanza Espino, Guadalupe; Soto, Luis A.
20150101
The surficial sediments recovered from 12 sites located near the channel axis of the Florida Straits and the lower slope off NW Cuba were analyzed for total organic carbon (TOC), nitrogen (TN), phosphorus (TP), elemental C:N:P ratios, C and N isotopic values, and 14C dating. The depth profiles of TOC, TN, and TP (018 cm) displayed a downcore trend and a significant variation. The TOC values were low (0.15 to 0.62%; 66 to 516 µmol g1). Sites near the island’s lower slope had lower TOC average concentrations (158333 µmol g1) than those closer to the channel axis (averaging 341516 µmol g1; p <0.05). The TN concentrations near the lower slope attained 0.11% (80 µmol g1), whereas, towards the channel axis, they decreased to 0.07% (55 µmol g1; p<0.05). The C:N ratios ranged from 1.9 to 10.2. The mean molar C:N ratio (5.4) indicated a marine hemipelagic deposition. The TP was lower at sites near the lower slope (38.4 to 50.0 µmol g1; 0.12% to 0.16%) than those near the channel axis (50.0 to 66 µmol g1; 0.15 to 0.21%). C:P fluctuated from 7.7 to 14.1 in the surficial sediment layer. The bulk organic δ13Corg and δ15N values confirmed pelagic organic sources, and the 14C dating revealed that the sediments were deposited during the Holocene (10005000 yr BP). We suggest that the hydrodynamic conditions in the Straits influence vertical and advective fluxes of particulate organic material trapped in the mixedlayer, which reduces the particulate matter flux to the seabed. PMID:26110791

Kapelner, Adam; Krieger, Abba; Blanford, William J
20161014
When measuring Henry's law constants (k H ) using the phase ratio variation (PRV) method via headspace gas chromatography (G C ), the value of k H of the compound under investigation is calculated from the ratio of the slope to the intercept of a linear regression of the inverse G C response versus the ratio of gas to liquid volumes of a series of vials drawn from the same parent solution. Thus, an experimenter collects measurements consisting of the independent variable (the gas/liquid volume ratio) and dependent variable (the G C 1 peak area). A review of the literature found that the common design is a simple uniform spacing of liquid volumes. We present an optimal experimental design which estimates k H with minimum error and provides multiple means for building confidence intervals for such estimates. We illustrate performance improvements of our design with an example measuring the k H for Naphthalene in aqueous solution as well as simulations on previous studies. Our designs are most applicable after a trial run defines the linear G C response and the linear phase ratio to the G C 1 region (where the PRV method is suitable) after which a practitioner can collect measurements in bulk. The designs can be easily computed using our open source software optDesignSlopeInt, an R package on CRAN. Copyright © 2016 Elsevier B.V. All rights reserved.

Methods for assessing the stability of slopes during earthquakesA retrospective
Jibson, R.W.
20110101
During the twentieth century, several methods to assess the stability of slopes during earthquakes were developed. Pseudostatic analysis was the earliest method; it involved simply adding a permanent body force representing the earthquake shaking to a static limitequilibrium analysis. Stressdeformation analysis, a later development, involved much more complex modeling of slopes using a mesh in which the internal stresses and strains within elements are computed based on the applied external loads, including gravity and seismic loads. Stressdeformation analysis provided the most realistic model of slope behavior, but it is very complex and requires a high density of highquality soilproperty data as well as an accurate model of soil behavior. In 1965, Newmark developed a method that effectively bridges the gap between these two types of analysis. His slidingblock model is easy to apply and provides a useful index of coseismic slope performance. Subsequent modifications to slidingblock analysis have made it applicable to a wider range of landslide types. Slidingblock analysis provides perhaps the greatest utility of all the types of analysis. It is far easier to apply than stressdeformation analysis, and it yields much more useful information than does pseudostatic analysis. ?? 2010.
 «
 1
 2
 3
 4
 5
 »
 «
 1
 2
 3
 4
 5
 »

The Stability Analysis Method of the Cohesive Granular Slope on the Basis of Graph Theory.
Guan, Yanpeng; Liu, Xiaoli; Wang, Enzhi; Wang, Sijing
20170227
This paper attempted to provide a method to calculate progressive failure of the cohesivefrictional granular geomaterial and the spatial distribution of the stability of the cohesive granular slope. The methodology can be divided into two parts: the characterization method of macrocontact and the analysis of the slope stability. Based on the graph theory, the vertexes, the edges and the edge sequences are abstracted out to characterize the voids, the particle contact and the macrocontact, respectively, bridging the gap between the mesoscopic and macro scales of granular materials. This paper adopts this characterization method to extract a graph from a granular slope and characterize the macro sliding surface, then the weighted graph is analyzed to calculate the slope safety factor. Each edge has three weights representing the sliding moment, the antisliding moment and the braking index of contactbond, respectively, . The safety factor of the slope is calculated by presupposing a certain number of sliding routes and reducing Weight repeatedly and counting the mesoscopic failure of the edge. It is a kind of slope analysis method from mesoscopic perspective so it can present more detail of the mesoscopic property of the granular slope. In the respect of macro scale, the spatial distribution of the stability of the granular slope is in agreement with the theoretical solution.

Zonation of LandslideProne Using Microseismic Method and Slope Analysis in Margoyoso, Magelang
NASA Astrophysics Data System (ADS)
Aditya, Muchamad Reza; Fauqi Romadlon, Arriqo’; Agra Medika, Reymon; Alfontius, Yosua; Delva Jannet, Zukhruf; Hartantyo, Eddy
20180401
Margoyoso Village, Salaman Subdistrict, Magelang Regency, Central Java is one of the villages that were included in landslide prone areas. The steep slopes and land use in this village were quite apprehensive. There were fractures with 5 cm in width and a length of 50 m. Moreover, these fractures appeared in the home residents. Although the local government has established a disaster response organization, this village is still not getting adequate information about the landslide prone areas. Based on the description before, we conducted research with geophysical methods and geotechnical analysis to minimize the danger of landslides. The geophysical method used in this research was microseismic method and geotechnical analysis. The microseismic measurement and slope stability analysis at Margoyoso village was a step in analysing the landslideprone zone boundary. The results of this research indicated that landslide potential areas had a low peak ground acceleration values with a range from 36 gal to 46 gal. Measurement of slope stability indicated that a slope angle values between 55°78° are a potential landslide slope because the soil in this village has very loose properties so it is very easy to move.

The Stability Analysis Method of the Cohesive Granular Slope on the Basis of Graph Theory
Guan, Yanpeng; Liu, Xiaoli; Wang, Enzhi; Wang, Sijing
20170101
This paper attempted to provide a method to calculate progressive failure of the cohesivefrictional granular geomaterial and the spatial distribution of the stability of the cohesive granular slope. The methodology can be divided into two parts: the characterization method of macrocontact and the analysis of the slope stability. Based on the graph theory, the vertexes, the edges and the edge sequences are abstracted out to characterize the voids, the particle contact and the macrocontact, respectively, bridging the gap between the mesoscopic and macro scales of granular materials. This paper adopts this characterization method to extract a graph from a granular slope and characterize the macro sliding surface, then the weighted graph is analyzed to calculate the slope safety factor. Each edge has three weights representing the sliding moment, the antisliding moment and the braking index of contactbond, respectively, E1E2E3E1E2E3. The safety factor of the slope is calculated by presupposing a certain number of sliding routes and reducing Weight E3 repeatedly and counting the mesoscopic failure of the edge. It is a kind of slope analysis method from mesoscopic perspective so it can present more detail of the mesoscopic property of the granular slope. In the respect of macro scale, the spatial distribution of the stability of the granular slope is in agreement with the theoretical solution. PMID:28772596

Stable estimate of primary OC/EC ratios in the EC tracer method
NASA Astrophysics Data System (ADS)
Chu, ShaoHang
In fine particulate matter studies, the primary OC/EC ratio plays an important role in estimating the secondary organic aerosol contribution to PM2.5 concentrations using the EC tracer method. In this study, numerical experiments are carried out to test and compare various statistical techniques in the estimation of primary OC/EC ratios. The influence of random measurement errors in both primary OC and EC measurements on the estimation of the expected primary OC/EC ratios is examined. It is found that random measurement errors in EC generally create an underestimation of the slope and an overestimation of the intercept of the ordinary leastsquares regression line. The Deming regression analysis performs much better than the ordinary regression, but it tends to overcorrect the problem by slightly overestimating the slope and underestimating the intercept. Averaging the ratios directly is usually undesirable because the average is strongly influenced by unrealistically high values of OC/EC ratios resulting from random measurement errors at low EC concentrations. The errors generally result in a skewed distribution of the OC/EC ratios even if the parent distributions of OC and EC are close to normal. When measured OC contains a significant amount of noncombustion OC Deming regression is a much better tool and should be used to estimate both the primary OC/EC ratio and the noncombustion OC. However, if the noncombustion OC is negligibly small the best and most robust estimator of the OC/EC ratio turns out to be the simple ratio of the OC and EC averages. It not only reduces random errors by averaging individual variables separately but also acts as a weighted average of ratios to minimize the influence of unrealistically high OC/EC ratios created by measurement errors at low EC concentrations. The median of OC/EC ratios ranks a close second, and the geometric mean of ratios ranks third. This is because their estimations are insensitive to questionable extreme

An alternative soil nailing system for slope stabilization: Akarpiles
NASA Astrophysics Data System (ADS)
Lim, ChunLan; Chan, CheeMing
20171101
This research proposes an innovative solution for slope stabilization with less environmental footprint: AKARPILES. In Malaysia, landslide has become common civil and environmental problems that cause impacts to the economy, safety and environment. Therefore, effective slope stabilization method helps to improve the safety of public and protect the environment. This study focused on stabilizing surfacial slope failure. The idea of AKARPILES was generated from the tree roots system in slope stabilization. After the piles are installed in the slope and intercepting the slip plane, grout was pumped in and discharged through holes on the piles. The grout then filled the pores in the soil with random flow within the slip zone. SKW mixture was used to simulate the soil slope. There were two designs being proposed in this study and the prototypes were produced by a 3D printer. Trial mix of the grout was carried out to obtain the optimum mixing ratio of bentonite: cement: water. A series of tests were conducted on the singlepilereinforced slope under vertical slope crest loading condition considering different slope gradients and nail designs. Parameters such as ultimate load, failure time and failure strain were recorded and compared. As comparison with the unreinforced slope, both designs of AKARPILES showed better but different performances in the model tests.

Porosity determination from 2D resistivity method in studying the slope failures
NASA Astrophysics Data System (ADS)
Maslinda, Umi; Nordiana, M. M.; Bery, A. A.
20170701
Slope failures have become the main focus for infrastructures development on hilly areas in Malaysia especially the development of tourism and residential. Lack of understanding and information of the subsoil conditions and geotechnical issues are the main cause of the slope failures. The failures happened are due to a combination of few factors such as topography, climate, geology and land use. 2D resistivity method was conducted at the collapsed area in Selangor. The 2D resistivity was done to study the instability of the area. The collapsed occurred because of the subsurface materials was unstable. Poledipole array was used with 5 m minimum electrode spacing for the 2D resistivity method. The data was processed using Res2Dinv software and the porosity was calculated using Archie's law equation. The results show that the saturated zone (1100 Ωm), alluvium or highly weathered rock (1001000 Ωm), boulders (16007000 Ωm) and granitic bedrock (>7000 Ωm). Generally, the slope failures or landslides occur during the wet season or after rainfall. It is because of the water infiltrate to the slope and cause the saturation of the slope which can lead to landslides. Then, the porosity of saturated zone is usually high because of the water content. The area of alluvium or highly weathered rock and saturated zone have high porosity (>20%) and the high porosity also dominated at almost all the collapsed area which means that the materials with porosity >20% is potential to be saturated, unstable and might trigger slope failures.

Influence of Weathering Depth and Fracture Intensity to Cutslope Movements
NASA Astrophysics Data System (ADS)
Yoon, W. S.; Choi, J. W.; Jeong, U.; Kim, J. H.
20030401
Generally, Failure modes in cut slopes are triggered by combination of various failure factors which have different effects on failure modes according to ground condition. It is, therefore, important to identify the behavioural characteristic of cut slope in that they reflect the failure mechanism. From the careful field investigation for 373 road cuts along the national highway in Korea, we analysed various types of failure modes for different ground conditions. The ground conditions which control failure modes of cut slopes and their related failure factors are dependent on weathering (or soil) depth and intensity of discontinuities in cut slopes. Firstly, the ratio of the soil depth and slope height (soil depth ratio; SR) is important parameter to classify ground conditions into soillike masses and rock masses. When a SR value is greater than 0.4, sliding failures on discontinuities do not occur. In this case, weathering condition, slope gradient and external rainfall play a key role on failure factors of cutslope. The proposed 0.4, therefore, is the critical SR value to identify the soillike masses and rock masses. Secondly, Intensity of discontinuities is expressed by block size ratio (BR), which is defined by the ratio of block size index (Ib; ISRM (1978)) and slope height. For a rock slope (SR<0.4), when BR is greater than 0.01, key failure modes in a cut slope are wedge sliding, fall and topple. In this case, attitudes and shear strength of discontinuities play an important role on behaviour of cutslope. When BR is less than 0.01, however, behaviour of cut slope shows circular sliding and surface failure like soillike mass. To sum up, we could divide the ground conditions in cutslope into 3 classes on the basis of SR (soil depth ratio) and BR (block size ratio); JRM (joint rock mass), HRM (highly fractured rock mass) and SLM (soillike mass). Moreover, to evaluate the stability of cutslope reasonably, it needs new evaluating categories having

Slope failures evaluation and landslides investigation using 2D resistivity method
NASA Astrophysics Data System (ADS)
Nordiana, M. M.; Azwin, I. N.; Nawawi, M. N. M.; Khalil, A. E.
20180601
Slope failure is a complex phenomenon that may caused to landslides. Buildings and infrastructure such as transportation facilities and pipelines located within the boundaries of a landslide can be damaged or destroyed. Slope failure classification and various factors contributing to the instability using 2D resistivity survey conducted in Selangor, Malaysia are described. Six 2D resistivity survey lines with 5 m minimum electrode spacing using Poledipole array were performed. The data were processed using Res2Dinv and surfer10 software to evaluate the subsurface characteristics. The 2D resistivity results show that the subsurface consist of two main zones. The first zone was alluvium or highly weathered with resistivity value of 1001000 Ω m and depth of >30 m. This zone consists of saturated area with resistivity value of 1100 Ω m and boulders with resistivity value of 12007000 Ω m. The second zone with resistivity value of >7000 Ω m was interpreted as granitic bedrock. The study area was characterized by saturated zones, highly weathered zone, highly contain of sand and boulders that will trigger slope failure in the survey area. This will cause to low strength of soil, debris flow and movement of earth. On the basis of the case examples described, 2D resistivity method is categorized into desirable and useful method in determination of slope failure and future assessments.

20140101
In the current practice, to determine the safety factor of a slope with twodimensional circular potential failure surface, one of the searching methods for the critical slip surface is Genetic Algorithm (GA), while the method to calculate the slope safety factor is Fellenius' slices method. However GA needs to be validated with more numeric tests, while Fellenius' slices method is just an approximate method like finite element method. This paper proposed a new method to determine the minimum slope safety factor which is the determination of slope safety factor with analytical solution and searching critical slip surface with GeneticTraversal Random Method. The analytical solution is more accurate than Fellenius' slices method. The GeneticTraversal Random Method uses random pick to utilize mutation. A computer automatic search program is developed for the GeneticTraversal Random Method. After comparison with other methods like slope/w software, results indicate that the GeneticTraversal Random Search Method can give very low safety factor which is about half of the other methods. However the obtained minimum safety factor with GeneticTraversal Random Search Method is very close to the lower bound solutions of slope safety factor given by the Ansys software. PMID:24782679

A rapid method for soil cement design : Louisiana slope value method : part II : evaluation.
DOT National Transportation Integrated Search
19660501
This report is an evaluation of the recently developed "Louisiana Slope Value Method". : The conclusion drawn are based on data from 637 separate samples representing nearly all major soil groups in Louisiana that are suitable for cement stabilizatio...

Regional comparisons of Vs30 and Spectral Ratio Methods
NASA Astrophysics Data System (ADS)
McNamara, D. E.; Gee, L. S.; Stephenson, W. J.; Odum, J. K.; Williams, R. A.; Hartzell, S.
20131201
Earthquake damage is often increased due to local groundmotion amplification in soft soils and thick basin sediments with factors such as topographic effects and water saturation. Seismic hazard assessments depend on detailed information on local site response and many different methods have been developed to estimate site response. Based on numerous empirical studies, the average shearwave velocity in the upper 30 m (Vs30) has become the most common means of classifying site conditions and has been adopted in the NEHRP design provisions for new buildings. In general, higher Vs30 values are associated with firm, dense rock and lower levels of ground shaking while lower Vs30 values are associated with softer soils and high site amplification. Vs30 is commonly computed by measuring the time it takes for shearwaves to travel from 30m depth to the surface using either active sources such as explosions or passive ambient noise microtremor sources. Since this approach is limited to locations where active measurements are undertaken, recent methods have sought to approximate Vs30 regionally, such as using topographic slope as a proxy. In this presentation, we compute a standard site response, horizontaltovertical spectral ratio (HVSR) using longterm power spectral density statistics of both ambient noise and earthquake signals at permanent and temporary seismic stations. We compare the HVSR results to surface observations of Vs30 and approximations using topographic slope in several different regions including the Eastern United States, St. Louis and the Los Angeles basin. In our comparison of the HVSR results to Vs30, we find that HVSR peak frequency can be used as a proxy for Vs30. Relationships between surface measured Vs30 and HVSR are less scattered than with Vs30 estimated using topographic approximations. In general, higher Vs30 is associated with higher HVSR peak frequency with variations in slope for different regions. We use these regional relationships to

Sarmabased keygroup method for rock slope reliability analyses
NASA Astrophysics Data System (ADS)
Yarahmadi Bafghi, A. R.; Verdel, T.
20050801
The methods used in conducting static stability analyses have remained pertinent to this day for reasons of both simplicity and speed of execution. The most wellknown of these methods for purposes of stability analysis of fractured rock masses is the keyblock method (KBM).This paper proposes an extension to the KBM, called the keygroup method (KGM), which combines not only individual keyblocks but also groups of collapsable blocks into an iterative and progressive analysis of the stability of discontinuous rock slopes. To take intragroup forces into account, the Sarma method has been implemented within the KGM in order to generate a Sarmabased KGM, abbreviated SKGM. We will discuss herein the hypothesis behind this new method, details regarding its implementation, and validation through comparison with results obtained from the distinct element method.Furthermore, as an alternative to deterministic methods, reliability analyses or probabilistic analyses have been proposed to take account of the uncertainty in analytical parameters and models. The FOSM and ASM probabilistic methods could be implemented within the KGM and SKGM framework in order to take account of the uncertainty due to physical and mechanical data (density, cohesion and angle of friction). We will then show how such reliability analyses can be introduced into SKGM to give rise to the probabilistic SKGM (PSKGM) and how it can be used for rock slope reliability analyses. Copyright

Jahanfar, Ali; Amirmojahedi, Mohsen; Gharabaghi, Bahram; Dubey, Brajesh; McBean, Edward; Kumar, Dinesh
20170301
Rapid population growth of major urban centres in many developing countries has created massive landfills with extraordinary heights and steep sideslopes, which are frequently surrounded by illegal lowincome residential settlements developed too close to landfills. These extraordinary landfills are facing high risks of catastrophic failure with potentially large numbers of fatalities. This study presents a novel method for risk assessment of landfill slope failure, using probabilistic analysis of potential failure scenarios and associated fatalities. The conceptual framework of the method includes selecting appropriate statistical distributions for the municipal solid waste (MSW) material shear strength and rheological properties for potential failure scenario analysis. The MSW material properties for a given scenario is then used to analyse the probability of slope failure and the resulting runout length to calculate the potential risk of fatalities. In comparison with existing methods, which are solely based on the probability of slope failure, this method provides a more accurate estimate of the risk of fatalities associated with a given landfill slope failure. The application of the new risk assessment method is demonstrated with a case study for a landfill located within a heavily populated area of New Delhi, India.

Stability Calculation Method of Slope Reinforced by Prestressed Anchor in Process of Excavation
Li, Zhong; Wei, Jia; Yang, Jun
20140101
This paper takes the effect of supporting structure and anchor on the slope stability of the excavation process into consideration; the stability calculation model is presented for the slope reinforced by prestressed anchor and grillage beam, and the dynamic search model of the critical slip surface also is put forward. The calculation model of the optimal stability solution of each anchor tension of the whole process is also given out, through which the realtime analysis and checking of slope stability in the process of excavation can be realized. The calculation examples indicate that the slope stability is changed with the dynamic change of the design parameters of anchor and grillage beam. So it is relatively more accurate and reasonable by using dynamic search model to determine the critical slip surface of the slope reinforced by prestressed anchor and grillage beam. Through the relationships of each anchor layout and the slope height of various stages of excavation, and the optimal stability solution of prestressed bolt tension design value in various excavation stages can be obtained. The arrangement of its prestressed anchor force reflects that the layout of the lower part of bolt and the calculation of slope reinforcement is in line with the actual. These indicate that the method is reasonable and practical. PMID:24683319

Stability calculation method of slope reinforced by prestressed anchor in process of excavation.
Li, Zhong; Wei, Jia; Yang, Jun
20140101
This paper takes the effect of supporting structure and anchor on the slope stability of the excavation process into consideration; the stability calculation model is presented for the slope reinforced by prestressed anchor and grillage beam, and the dynamic search model of the critical slip surface also is put forward. The calculation model of the optimal stability solution of each anchor tension of the whole process is also given out, through which the realtime analysis and checking of slope stability in the process of excavation can be realized. The calculation examples indicate that the slope stability is changed with the dynamic change of the design parameters of anchor and grillage beam. So it is relatively more accurate and reasonable by using dynamic search model to determine the critical slip surface of the slope reinforced by prestressed anchor and grillage beam. Through the relationships of each anchor layout and the slope height of various stages of excavation, and the optimal stability solution of prestressed bolt tension design value in various excavation stages can be obtained. The arrangement of its prestressed anchor force reflects that the layout of the lower part of bolt and the calculation of slope reinforcement is in line with the actual. These indicate that the method is reasonable and practical.

HDMR methods to assess reliability in slope stability analyses
NASA Astrophysics Data System (ADS)
Kozubal, Janusz; Pula, Wojciech; Vessia, Giovanna
20140501
Stability analyses of complex rocksoil deposits shall be tackled considering the complex structure of discontinuities within rock mass and embedded soil layers. These materials are characterized by a high variability in physical and mechanical properties. Thus, to calculate the slope safety factor in stability analyses two issues must be taken into account: 1) the uncertainties related to structural setting of the rockslope mass and 2) the variability in mechanical properties of soils and rocks. High Dimensional Model Representation (HDMR) (Chowdhury et al. 2009; Chowdhury and Rao 2010) can be used to carry out the reliability index within complex rocksoil slopes when numerous random variables with high coefficient of variations are considered. HDMR implements the inverse reliability analysis, meaning that the unknown design parameters are sought provided that prescribed reliability index values are attained. Such approach uses implicit response functions according to the Response Surface Method (RSM). The simple RSM can be efficiently applied when less than four random variables are considered; as the number of variables increases, the efficiency in reliability index estimation decreases due to the great amount of calculations. Therefore, HDMR method is used to improve the computational accuracy. In this study, the sliding mechanism in Polish Flysch Carpathian Mountains have been studied by means of HDMR. The Southern part of Poland where Carpathian Mountains are placed is characterized by a rather complicated sedimentary pattern of flysh rockysoil deposits that can be simplified into three main categories: (1) normal flysch, consisting of adjacent sandstone and shale beds of approximately equal thickness, (2) shale flysch, where shale beds are thicker than adjacent sandstone beds, and (3) sandstone flysch, where the opposite holds. Landslides occur in all flysch deposit types thus some configurations of possible unstable settings (within fractured rocky

Method of Preparation AZP4330 PR Pattern with Edge Slope 40°
NASA Astrophysics Data System (ADS)
Wu, Jie; Zhao, Hongyuan; Yu, Yuanwei; Zhu, Jian
20180301
When the edge which is under the multifilm is more steep or angular, the stress in the multilayer film near the edge is concentrated, this situation will greatly reduce the reliability of electronic components. And sometimes, we need some special structure such as a slope with a specific angle in the MEMS, so that the metal line can take the signal to the output pad through the slope instead of deep step. To cover these problems, the lithography method of preparing the structure with edge slope is studied. In this paper, based on the Kirchhoff scalar diffraction theory we try to change the contact exposure gap and the postbaking time at the specific temperature to find out the effect about the edge angle of the photoresist. After test by SEM, the results were presented by using AZP4330 photoresist, we can get the PR Pattern with edge slope 40° of the process and the specific process parameters.

NASA Astrophysics Data System (ADS)
Dadashzadeh, N.; Duzgun, H. S. B.; YesilogluGultekin, N.
20170801
While advanced numerical techniques in slope stability analysis are successfully used in deterministic studies, they have so far found limited use in probabilistic analyses due to their high computation cost. The firstorder reliability method (FORM) is one of the most efficient probabilistic techniques to perform probabilistic stability analysis by considering the associated uncertainties in the analysis parameters. However, it is not possible to directly use FORM in numerical slope stability evaluations as it requires definition of a limit state performance function. In this study, an integrated methodology for probabilistic numerical modeling of rock slope stability is proposed. The methodology is based on response surface method, where FORM is used to develop an explicit performance function from the results of numerical simulations. The implementation of the proposed methodology is performed by considering a large potential rock wedge in Sumela Monastery, Turkey. The accuracy of the developed performance function to truly represent the limit state surface is evaluated by monitoring the slope behavior. The calculated probability of failure is compared with Monte Carlo simulation (MCS) method. The proposed methodology is found to be 72% more efficient than MCS, while the accuracy is decreased with an error of 24%.

A simplified approach for slope stability analysis of uncontrolled waste dumps.
Turer, Dilek; Turer, Ahmet
20110201
Slope stability analysis of municipal solid waste has always been problematic because of the heterogeneous nature of the waste materials. The requirement for large testing equipment in order to obtain representative samples has identified the need for simplified approaches to obtain the unit weight and shear strength parameters of the waste. In the present study, two of the most recently published approaches for determining the unit weight and shear strength parameters of the waste have been incorporated into a slope stability analysis using the Bishop method to prepare slope stability charts. The slope stability charts were prepared for uncontrolled waste dumps having no liner and leachate collection systems with pore pressure ratios of 0, 0.1, 0.2, 0.3, 0.4 and 0.5, considering the most critical slip surface passing through the toe of the slope. As the proposed slope stability charts were prepared by considering the change in unit weight as a function of height, they reflect field conditions better than accepting a constant unit weight approach in the stability analysis. They also streamline the selection of slope or height as a function of the desired factor of safety.

Numbercounts slope estimation in the presence of Poisson noise
NASA Technical Reports Server (NTRS)
Schmitt, Juergen H. M. M.; Maccacaro, Tommaso
19860101
The slope determination of a powerlaw number flux relationship in the case of photonlimited sampling. This case is important for highsensitivity Xray surveys with imaging telescopes, where the error in an individual source measurement depends on integrated flux and is Poisson, rather than Gaussian, distributed. A biasfree method of slope estimation is developed that takes into account the exact error distribution, the influence of background noise, and the effects of varying limiting sensitivities. It is shown that the resulting bias corrections are quite insensitive to the bias correction procedures applied, as long as only sources with signaltonoise ratio five or greater are considered. However, if sources with signaltonoise ratio five or less are included, the derived bias corrections depend sensitively on the shape of the error distribution.
 «
 1
 2
 3
 4
 5
 »
 «
 1
 2
 3
 4
 5
 »

Slope monitoring by using 2D resistivity method at Sungai Batu, Pulau Pinang, Malaysia
NASA Astrophysics Data System (ADS)
Azman, Muhamad Iqbal Mubarak Faharul; Yusof, Azim Hilmy Mohd; Ismail, Nur Azwin; Ismail, Noer El Hidayah
20170701
Slope is a dynamic system of geoenvironmental phenomena that related to the movement of the soil and rock masses. In Pulau Pinang, the occurrence of slope related phenomena such as landslide and rock fall has become a huge issue especially during rainy season as the government would have to invest more for the people safety. 2D resistivity method is one of the geophysical methods that can be applied to overcome this issue thus prepare countermeasure actions. Monitoring is one of the common acquisition technique that has been used in solving such issue. This technique was applied to identify and monitor changes at the suspected area and thus, countermeasure steps can be taken accordingly and not blindfolded. Starting from August until November 2016, a 200 m survey line of 2D resistivity survey had been conducted monthly at Sungai Batu, Pulau Pinang slope for monitoring purpose. Three resistivity ranges were able to detect within the subsurface. Resistivity value of 250  400 Ωm indicated the low resistivity value and interpreted as the weak zone located at distance of 90  120 m with depth of 10 m. Intermediate resistivity value was interpreted as weathered granite zone with resistivity value of 400  1500 Ωm was found at almost along survey line. High resistivity value was > 5000 Ωm and interpreted as granitic bedrock located at depth of > 20 m. Aside from weathered granite zone and weak zone, a fracture was found develop over time at distance of 130  140 m. The features found have the potential to be the cause for slope failure phenomena to occur. As a conclusion, monitoring slope using 2D resistivity method is a success and indeed helpful in overcome landslide and rock fall issue as a precountermeasure action.

Establish Effective Lower Bounds of Watershed Slope for Traditional Hydrologic Methods
DOT National Transportation Integrated Search
20120601
Equations to estimate timing parameters for a watershed contain watershed slope as a principal parameter and : estimates are usually inversely proportional to topographic slope. Hence as slope vanishes, the estimates approach : infinity. The research...

Bradley, D. Nathan
20120101
The slopearea method is a technique for estimating the peak discharge of a flood after the water has receded (Dalrymple and Benson, 1967). This type of discharge estimate is called an “indirect measurement” because it relies on evidence left behind by the flood, such as highwater marks (HWMs) on trees or buildings. These indicators of flood stage are combined with measurements of the crosssectional geometry of the stream, estimates of channel roughness, and a mathematical model that balances the total energy of the flow between cross sections. This is in contrast to a “direct” measurement of discharge during the flood where crosssectional area is measured and a current meter or acoustic equipment is used to measure the water velocity. When a direct discharge measurement cannot be made at a gage during high flows because of logistics or safety reasons, an indirect measurement of a peak discharge is useful for defining the highflow section of the stagedischarge relation (rating curve) at the stream gage, resulting in more accurate computation of high flows. The SlopeArea Computation program (SAC; Fulford, 1994) is an implementation of the slopearea method that computes a peakdischarge estimate from inputs of watersurface slope (from surveyed HWMs), channel geometry, and estimated channel roughness. SAC is a command line program written in Fortran that reads input data from a formatted text file and prints results to another formatted text file. Preparing the input file can be timeconsuming and prone to errors. This document describes the SAC graphical user interface (GUI), a crossplatform “wrapper” application that prepares the SAC input file, executes the program, and helps the user interpret the output. The SAC GUI is an update and enhancement of the slopearea method (SAM; Hortness, 2004; Berenbrock, 1996), an earlier spreadsheet tool used to aid field personnel in the completion of a slopearea measurement. The SAC GUI reads survey data

Slope tomography based on eikonal solvers and the adjointstate method
NASA Astrophysics Data System (ADS)
Tavakoli F., B.; Operto, S.; Ribodetti, A.; Virieux, J.
20170601
Velocity macromodel building is a crucial step in the seismic imaging workflow as it provides the necessary background model for migration or full waveform inversion. In this study, we present a new formulation of stereotomography that can handle more efficiently longoffset acquisition, complex geological structures and largescale data sets. Stereotomography is a slope tomographic method based upon a semiautomatic picking of local coherent events. Each local coherent event, characterized by its twoway traveltime and two slopes in commonshot and commonreceiver gathers, is tied to a scatterer or a reflector segment in the subsurface. Ray tracing provides a natural forward engine to compute traveltime and slopes but can suffer from nonuniform ray sampling in presence of complex media and longoffset acquisitions. Moreover, most implementations of stereotomography explicitly build a sensitivity matrix, leading to the resolution of large systems of linear equations, which can be cumbersome when largescale data sets are considered. Overcoming these issues comes with a new matrixfree formulation of stereotomography: a factored eikonal solver based on the fast sweeping method to compute firstarrival traveltimes and an adjointstate formulation to compute the gradient of the misfit function. By solving eikonal equation from sources and receivers, we make the computational cost proportional to the number of sources and receivers while it is independent of picked events density in each shot and receiver gather. The model space involves the subsurface velocities and the scatterer coordinates, while the dips of the reflector segments are implicitly represented by the spatial support of the adjoint sources and are updated through the joint localization of nearby scatterers. We present an application on the complex Marmousi model for a towedstreamer acquisition and a realistic distribution of local events. We show that the estimated model, built without any prior

Methods for Meeting the Intent of the ADA in Sidewalk CrossSlope Design
DOT National Transportation Integrated Search
20000101
This summary report is a review of research undertaken to determine appropriate sidewalk crossslope design in accordance wit the Americans with Disabilities Act (ADA). The research methods used are described and specific recommendations are provided...

Numerical computation of hom*ogeneous slope stability.
Xiao, Shuangshuang; Li, Kemin; Ding, Xiaohua; Liu, Tong
20150101
To simplify the computational process of hom*ogeneous slope stability, improve computational accuracy, and find multiple potential slip surfaces of a complex geometric slope, this study utilized the limit equilibrium method to derive expression equations of overall and partial factors of safety. This study transformed the solution of the minimum factor of safety (FOS) to solving of a constrained nonlinear programming problem and applied an exhaustive method (EM) and particle swarm optimization algorithm (PSO) to this problem. In simple slope examples, the computational results using an EM and PSO were close to those obtained using other methods. Compared to the EM, the PSO had a small computation error and a significantly shorter computation time. As a result, the PSO could precisely calculate the slope FOS with high efficiency. The example of the multistage slope analysis indicated that this slope had two potential slip surfaces. The factors of safety were 1.1182 and 1.1560, respectively. The differences between these and the minimum FOS (1.0759) were small, but the positions of the slip surfaces were completely different than the critical slip surface (CSS).

How Do Adults Perceive, Analyse and Measure Slope?
ERIC Educational Resources Information Center
Duncan, Bruce; Chick, Helen
20130101
Slope is a mathematical concept that is both fundamental to the study of advanced calculus and commonly perceived in everyday life. The measurement of steepness of terrain as a ratio is an example of an everyday application the concept of slope. In this study, a group of preservice teachers were tested for their capacity to mathematize the…

Analysing hydromechanical behaviour of reinforced slopes through centrifuge modelling
NASA Astrophysics Data System (ADS)
Veenhof, Rick; Wu, Wei
20170401
Every year, slope instability is causing casualties and damage to properties and the environment. The behaviour of slopes during and after these kind of events is complex and depends on meteorological conditions, slope geometry, hydromechanical soil properties, boundary conditions and the initial state of the soils. This study describes the effects of adding reinforcement, consisting of randomly distributed polyolefin monofilament fibres or Ryegrass (Lolium), on the behaviour of mediumfine sand in loose and medium dense conditions. Direct shear tests were performed on sand specimens with different void ratios, water content and fibre or root density, respectively. To simulate the stress state of real scale field situations, centrifuge model tests were conducted on sand specimens with different slope angles, thickness of the reinforced layer, fibre density, void ratio and water content. An increase in peak shear strength is observed in all reinforced cases. Centrifuge tests show that for slopes that are reinforced the period until failure is extended. The location of shear band formation and patch displacement behaviour indicate that the design of slope reinforcement has a significant effect on the failure behaviour. Future research will focus on the effect of plant water uptake on soil cohesion.

NASA Astrophysics Data System (ADS)
Arya, I. W.; Wiraga, I. W.; GAG Suryanegara, I.
20180101
Slope is a part of soil topography formed due to elevation difference from two soil surface. Landslides is frequently occur in natural slope, it is because shear force is greater than shear strength in the soil. There are some factor that influence slope stability such as: rain dissipation, vibration from earthquake, construction and crack in the soil. Slope instability can cause risk in human activity or even threaten human lives. Every years in rainy season, landslides always occur in Indonesia. In 2016, there was some landslide occurred in Bali. One of the most damaging is landslide in Petang district, Badung regency. This landslide caused main road closed entirely. In order to overcome and prevent landslide, a lot of method have been practiced and still looking for more sophisticated method for forecasting slope stability. One of the method to strengthen soil stability is filling the soil pores with some certain material. Cement is one of the material that can be used to fill the soil pores because when it is in liquid form, it can infiltrate into soil pores and fill the gap between soil particles. And after it dry, it can formed a bond with soil particle so that soil become stronger and the slope as well. In this study, it will use experimental method, slope model in laboratory to simulate a real slope behavior in the field. The first model is the slope without any addition of cement. This model will be become a benchmark for the other models. The second model is a slope with improved soil that injects the slope with cement. Injection of cement is done with varying interval distance of injection point is 5 cm and 10 cm. Each slope model will be given a load until the slope collapses. The slope model will also be analyzed with slope stability program. The test results on the improved slope models will be compared with unimproved slope. In the initial test will consist of 3 model. First model is soil without improvement or cement injection, second model is soil

Numerical Computation of hom*ogeneous Slope Stability
Xiao, Shuangshuang; Li, Kemin; Ding, Xiaohua; Liu, Tong
20150101
To simplify the computational process of hom*ogeneous slope stability, improve computational accuracy, and find multiple potential slip surfaces of a complex geometric slope, this study utilized the limit equilibrium method to derive expression equations of overall and partial factors of safety. This study transformed the solution of the minimum factor of safety (FOS) to solving of a constrained nonlinear programming problem and applied an exhaustive method (EM) and particle swarm optimization algorithm (PSO) to this problem. In simple slope examples, the computational results using an EM and PSO were close to those obtained using other methods. Compared to the EM, the PSO had a small computation error and a significantly shorter computation time. As a result, the PSO could precisely calculate the slope FOS with high efficiency. The example of the multistage slope analysis indicated that this slope had two potential slip surfaces. The factors of safety were 1.1182 and 1.1560, respectively. The differences between these and the minimum FOS (1.0759) were small, but the positions of the slip surfaces were completely different than the critical slip surface (CSS). PMID:25784927

Spectral ratio method for measuring emissivity
Watson, K.
19920101
The spectral ratio method is based on the concept that although the spectral radiances are very sensitive to small changes in temperature the ratios are not. Only an approximate estimate of temperature is required thus, for example, we can determine the emissivity ratio to an accuracy of 1% with a temperature estimate that is only accurate to 12.5 K. Selecting the maximum value of the channel brightness temperatures is an unbiased estimate. Laboratory and field spectral data are easily converted into spectral ratio plots. The ratio method is limited by system signal:noise and spectral bandwidth. The images can appear quite noisy because ratios enhance high frequencies and may require spatial filtering. Atmospheric effects tend to rescale the ratios and require using an atmospheric model or a calibration site. ?? 1992.

Infiltration on sloping terrain and its role on runoff generation and slope stability
NASA Astrophysics Data System (ADS)
Loáiciga, Hugo A.; Johnson, J. Michael
20180601
A modified GreenandAmpt model is formulated to quantify infiltration on sloping terrain underlain by hom*ogeneous soil wetted by surficial water application. This paper's theory for quantifying infiltration relies on the mathematical statement of the coupled partial differential equations (pdes) governing infiltration and runoff. These pdes are solved by employing an explicit finitedifference numerical method that yields the infiltration, the infiltration rate, the depth to the wetting front, the rate of runoff, and the depth of runoff everywhere on the slope during external wetting. Data inputs consist of a water application rate or the rainfall hyetograph of a storm of arbitrary duration, soil hydraulic characteristics and antecedent moisture, and the slope's hydraulic and geometric characteristics. The presented theory predicts the effect an advancing wetting front has on slope stability with respect to translational sliding. This paper's theory also develops the 1D pde governing suspended sediment transport and slope degradation caused by runoff influenced by infiltration. Three examples illustrate the application of the developed theory to calculate infiltration and runoff on a slope and their role on the stability of cohesive and cohesionless soils forming sloping terrain.

Prediction of Groundwater Level at Slope Areas using Electrical Resistivity Method
NASA Astrophysics Data System (ADS)
Baharuddin, M. F. T.; Hazreek, Z. A. M.; Azman, M. A. A.; Madun, A.
20180401
Groundwater level plays an important role as an agent that triggers landslides. Commonly, the conventional method used to monitor the groundwater level is done by using standpipe piezometer. There were several disadvantages of the conventional method related to cost, time and data coverage. The aim of this study is to determine groundwater level at slope areas using electrical resistivity method and to verify groundwater level of the study area with standpipe piezometer data. The data acquisition was performed using ABEM Terrameter SAS4000. For data analysis and processing, RES2DINV and SURFER were used. The groundwater level was calibrated with reference of standpipe piezometer based on electrical resistivity value (ERV).

Lee, SangYeol
20160901
[Purpose] The purpose of this study was to provide basic data for research on selective muscle strengthening by identifying mean muscle activities and calculating muscle ratios for use in developing strengthening methods. [Subjects and Methods] Twentyone healthy volunteers were included in this study. Muscle activity was measured during a oneleg stance under 6 conditions of slope angle: 0°, 5°, 10°, 15°, 20°, and 25°. The data used in the analysis were root mean square and % total muscle activity values. [Results] There were significant differences in the root mean square of the gluteus medius, the hamstring, and the medial gastrocnemius muscles. There were significant differences in % total muscle activity of the medial gastrocnemius. [Conclusion] Future studies aimed at developing selective muscle strengthening methods are likely to yield more effective results by using muscle activity ratios based on electromyography data.

Eberhard, Wynn L
20170401
The maximum likelihood estimator (MLE) is derived for retrieving the extinction coefficient and zerorange intercept in the lidar slope method in the presence of random and independent Gaussian noise. Leastsquares fitting, weighted by the inverse of the noise variance, is equivalent to the MLE. Monte Carlo simulations demonstrate that two traditional leastsquares fitting schemes, which use different weights, are less accurate. Alternative fitting schemes that have some positive attributes are introduced and evaluated. The principal factors governing accuracy of all these schemes are elucidated. Applying these schemes to data with Poisson rather than Gaussian noise alters accuracy little, even when the signaltonoise ratio is low. Methods to estimate optimum weighting factors in actual data are presented. Even when the weighting estimates are coarse, retrieval accuracy declines only modestly. Mathematical tools are described for predicting retrieval accuracy. Leastsquares fitting with inverse variance weighting has optimum accuracy for retrieval of parameters from singlewavelength lidar measurements when noise, errors, and uncertainties are Gaussian distributed, or close to optimum when only approximately Gaussian.

Winterdahl, Michael; Sørensen, Michael; Keiding, Susanne; Mortensen, Frank V.; Alstrup, Aage K. O.; Hansen, Søren B.; Munk, Ole L.
20120101
Objective To determine whether dynamic contrastenhanced computed tomography (DCECT) and the slope method can provide absolute measures of hepatic blood perfusion from hepatic artery (HA) and portal vein (PV) at experimentally varied blood flow rates. Materials and Methods Ten anesthetized 40kg pigs underwent DCECT during periods of normocapnia (normal flow), hypocapnia (decreased flow), and hypercapnia (increased flow), which was induced by adjusting the ventilation. Reference blood flows in HA and PV were measured continuously by surgicallyplaced ultrasound transittime flowmeters. For each capnic condition, the DCECT estimated absolute hepatic blood perfusion from HA and PV were calculated using the slope method and compared with flowmeter based absolute measurements of hepatic perfusions and relative errors were analyzed. Results The relative errors (mean±SEM) of the DCECT based perfusion estimates were −21±23% for HA and 81±31% for PV (normocapnia), 9±23% for HA and 92±42% for PV (hypocapnia), and 64±28% for HA and −2±20% for PV (hypercapnia). The mean relative errors for HA were not significantly different from zero during hypo and normocapnia, and the DCECT slope method could detect relative changes in HA perfusion between scans. Infusion of contrast agent led to significantly increased hepatic blood perfusion, which biased the PV perfusion estimates. Conclusions Using the DCECT slope method, HA perfusion estimates were accurate at low and normal flow rates whereas PV perfusion estimates were inaccurate and imprecise. At high flow rate, both HA perfusion estimates were significantly biased. PMID:22836307

Mapping slope movements in Alpine environments using TerraSARX interferometric methods
NASA Astrophysics Data System (ADS)
Barboux, Chloé; Strozzi, Tazio; Delaloye, Reynald; Wegmüller, Urs; Collet, Claude
20151101
Mapping slope movements in Alpine environments is an increasingly important task in the context of climate change and natural hazard management. We propose the detection, mapping and inventorying of slope movements using different interferometric methods based on TerraSARX satellite images. Differential SAR interferograms (DInSAR), Persistent Scatterer Interferometry (PSI), ShortBaseline Interferometry (SBAS) and a semiautomated texture image analysis are presented and compared in order to determine their contribution for the automatic detection and mapping of slope movements of various velocity rates encountered in Alpine environments. Investigations are conducted in a study region of about 6 km × 6 km located in the Western Swiss Alps using a unique large data set of 140 DInSAR scenes computed from 51 summer TerraSARX (TSX) acquisitions from 2008 to 2012. We found that PSI is able to precisely detect only points moving with velocities below 3.5 cm/yr in the LOS, with a root mean squared error of about 0.58 cm/yr compared to DGPS records. SBAS employed with 11 days summer interferograms increases the range of detectable movements to rates up to 35 cm/yr in the LOS with a root mean squared error of 6.36 cm/yr, but inaccurate measurements due to phase unwrapping are already possible for velocity rates larger than 20 cm/year. With the semiautomated texture image analysis the rough estimation of the velocity rates over an outlined moving zone is accurate for rates of "cm/day", "dm/month" and "cm/month", but due to the decorrelation of yearly TSX interferograms this method fails for the observation of slow movements in the "cm/yr" range.

Coordinated control of slip ratio for wheeled mobile robots climbing loose sloped terrain.
Li, Zhengcai; Wang, Yang
20140101
A challenging problem faced by wheeled mobile robots (WMRs) such as planetary rovers traversing loose sloped terrain is the inevitable longitudinal slip suffered by the wheels, which often leads to their deviation from the predetermined trajectory, reduced drive efficiency, and possible failures. This study investigates this problem using terramechanics analysis of the wheelsoil interaction. First, a slopebased wheelsoil interaction terramechanics model is built, and an online slip coordinated algorithm is designed based on the goal of optimal drive efficiency. An equation of state is established using the coordinated slip as the desired input and the actual slip as a state variable. To improve the robustness and adaptability of the control system, an adaptive neural network is designed. Analytical results and those of a simulation using Vortex demonstrate the significantly improved mobile performance of the WMR using the proposed control system.

Yu, L; Batlle, F
20111201
Limited space for accommodating the ever increasing mounds of municipal solid waste (MSW) demands the capacity of MSW landfill be maximized by building landfills to greater heights with steeper slopes. This situation has raised concerns regarding the stability of high MSW landfills. A hybrid method for quasithreedimensional slope stability analysis based on the finite element stress analysis was applied in a case study at a MSW landfill in northeast Spain. Potential slides can be assumed to be located within the waste mass due to the lack of weak foundation soils and geosynthetic membranes at the landfill base. The only triggering factor of deepseated slope failure is the higher leachate level and the relatively high and steep slope in the front. The valleyshaped geometry and layered construction procedure at the site make threedimensional slope stability analyses necessary for this landfill. In the finite element stress analysis, variations of leachate level during construction and continuous settlement of the landfill were taken into account. The "equivalent" threedimensional factor of safety (FoS) was computed from the individual result of the twodimensional analysis for a series of evenly spaced cross sections within the potential sliding body. Results indicate that the hybrid method for quasithreedimensional slope stability analysis adopted in this paper is capable of locating roughly the spatial position of the potential sliding mass. This easy to manipulate method can serve as an engineering tool in the preliminary estimate of the FoS as well as the approximate position and extent of the potential sliding mass. The result that FoS obtained from threedimensional analysis increases as much as 50% compared to that from twodimensional analysis implies the significance of the threedimensional effect for this studycase. Influences of shear parameters, time elapse after landfill closure, leachate level as well as unit weight of waste on FoS were also

Aardsma, M P; Parsons, C M
20170101
The precisionfed rooster assay (PFRA) frequently yields TME n values for fats and oils in excess of their gross energies. Six experiments were conducted to determine if the PFRA could be combined with a sloperatio type assay to yield more useful lipid TME n values. In experiment (EXP) 1, refined corn oil (RCO) was fed to conventional and cecectomized roosters at zero, 5, 10, 15, and 20% of a ground corn diet. In EXP 2 through 6, lipids were fed to conventional roosters at zero, 5, and 10% in a ground corn diet. Palomys (a novel lipid), high stearidonic acid soybean oil (SDASO), 2 animalvegetable blends (AV1, AV2), a vegetablebased oil blend (VB), and corn oil from an ethanol plant (DDGSCO) were evaluated and compared to refined soybean oil (RSO) or RCO as the reference lipid. Multiple linear regression of diet TME n on supplemental lipid level generated regression coefficients that were used to calculate relative bioavailability values (RBV). In EXP 1, RCO was a suitable reference material as TME n linearly increased up to 20% RCO inclusion. There were some minor differences in TME n of RCO between conventional and cecetomized bird types. In EXP 2, Palomys was found to have a lower (P < 0.05) RBV (87%) than RCO. In EXP 3, there were no significant differences between SDASO and RSO. In EXP 4, the RBV of AV2 (79%) was lower (P<0.05) than RCO, while the RBV of AV1 was not different from RCO. The RBV of DDGSCO (116%) was higher (P < 0.05) than RCO in EXP 5. The RBV of VB (84%) was lower (P < 0.001) than RCO in EXP 6; however, this may be an underestimation for low levels of VB, as there was an interaction (P < 0.01) between lipid type and lipid supplementation level. These results indicate that the precisionfed sloperatio rooster assay can detect differences among lipids and yields practically useful lipid TME n values. © 2016 Poultry Science Association Inc.
 «
 1
 2
 3
 4
 5
 »
 «
 2
 3
 4
 5
 6
 »

Coordinated Control of Slip Ratio for Wheeled Mobile Robots Climbing Loose Sloped Terrain
Li, Zhengcai; Wang, Yang
20140101
A challenging problem faced by wheeled mobile robots (WMRs) such as planetary rovers traversing loose sloped terrain is the inevitable longitudinal slip suffered by the wheels, which often leads to their deviation from the predetermined trajectory, reduced drive efficiency, and possible failures. This study investigates this problem using terramechanics analysis of the wheelsoil interaction. First, a slopebased wheelsoil interaction terramechanics model is built, and an online slip coordinated algorithm is designed based on the goal of optimal drive efficiency. An equation of state is established using the coordinated slip as the desired input and the actual slip as a state variable. To improve the robustness and adaptability of the control system, an adaptive neural network is designed. Analytical results and those of a simulation using Vortex demonstrate the significantly improved mobile performance of the WMR using the proposed control system. PMID:25276849

Dipslope and Dipslope Failures in Taiwan  a Review
NASA Astrophysics Data System (ADS)
Lee, C.
20111201
Taiwan is famous for dipslope and dipslope slides. Dipslopes exist at many places in the foldandthrust belt of Taiwan. Under active cutting of stream channels and manmade excavations, a dipslope may become unstable and susceptible for mass sliding. Daylight of a bedding parallel clay seam is the most dangerous type for dipslope sliding. Buckling or shearoff features may also happen at toe of a long dipslope. Besides, a dipslope is also dangerous for shallow debris slides, if the slope angle is between 25 to 45 degrees and the debris (colluvium or slope wash) is thick (>1m). These unstable slopes may slide during a triggering event, earthquake or typhoon storm; or even slide without a triggering event, like the 2010 Tapu case. Initial buckling feature had been found in the dipslope of the Feitsui arch dam abutment after detailed explorations. Shearoff feature have also been found in dipslope located in right bank of the Nahua reservoir after field investigation and drilling. The Chiufengerhshan slide may also be shearoff type. On the other hand, the Tapu, the Tsaoling slides and others are of direct slide type. The Neihoo Bishan slide is a shallow debris slide on dipslope. All these cases demonstrate the four different types of dipslope slide. The hazard of a dipslope should be investigated to cover these possible types of failure. The existence of bedding parallel clay seams is critical for the stability of a dipslope, either for direct slide or buckling or shearoff type of failure, and is a hot point during investigation. Because, the stability of a dipslope is changing with time, therefore, detailed explorations to including weathering and erosion rates are also very necessary to ensure the longterm stability of a dipslope.

Automatic approach to deriving fuzzy slope positions
NASA Astrophysics Data System (ADS)
Zhu, LiangJun; Zhu, A.Xing; Qin, ChengZhi; Liu, JunZhi
20180301
Fuzzy characterization of slope positions is important for geographic modeling. Most of the existing fuzzy classificationbased methods for fuzzy characterization require extensive user intervention in data preparation and parameter setting, which is tedious and timeconsuming. This paper presents an automatic approach to overcoming these limitations in the prototypebased inference method for deriving fuzzy membership value (or similarity) to slope positions. The key contribution is a procedure for finding the typical locations and setting the fuzzy inference parameters for each slope position type. Instead of being determined totally by users in the prototypebased inference method, in the proposed approach the typical locations and fuzzy inference parameters for each slope position type are automatically determined by a rule set based on prior domain knowledge and the frequency distributions of topographic attributes. Furthermore, the preparation of topographic attributes (e.g., slope gradient, curvature, and relative position index) is automated, so the proposed automatic approach has only one necessary input, i.e., the gridded digital elevation model of the study area. All computeintensive algorithms in the proposed approach were speeded up by parallel computing. Two study cases were provided to demonstrate that this approach can properly, conveniently and quickly derive the fuzzy slope positions.

Effects of wind velocity and slope on fire behavior
D.R. Weise; G.S. Biging
19940101
Effects of wind velocity and slope on fire spread rate and flame length were examined. Fuel beds of vertical sticks (13.97 cm x 0.455 cm x 0.1 10 cm) and coarse excelsior were burned in an opentopped tilting wind tunnel. Mean fuel moisture content of sticks and excelsior was 11% and 12%, respectively. Mean surface area to volume ratio was 23 cm! Five slopes (negative...

30 CFR 56.3130  Wall, bank, and slope stability.
Code of Federal Regulations, 2010 CFR
20100701
... 30 Mineral Resources 1 20100701 20100701 false Wall, bank, and slope stability. 56.3130... Mining Methods § 56.3130 Wall, bank, and slope stability. Mining methods shall be used that will maintain wall, bank, and slope stability in places where persons work or travel in performing their assigned...

Analysis of rainfallinduced slope instability using a field of local factor of safety
Lu, Ning; ŞenerKaya, Başak; Wayllace, Alexandra; Godt, Jonathan W.
20120101
Slopestability analyses are mostly conducted by identifying or assuming a potential failure surface and assessing the factor of safety (FS) of that surface. This approach of assigning a single FS to a potentially unstable slope provides little insight on where the failure initiates or the ultimate geometry and location of a landslide rupture surface. We describe a method to quantify a scalar field of FS based on the concept of the Coulomb stress and the shift in the state of stress toward failure that results from rainfall infiltration. The FS at each point within a hillslope is called the local factor of safety (LFS) and is defined as the ratio of the Coulomb stress at the current state of stress to the Coulomb stress of the potential failure state under the MohrCoulomb criterion. Comparative assessment with limitequilibrium and hybrid finite element limitequilibrium methods show that the proposed LFS is consistent with these approaches and yields additional insight into the geometry and location of the potential failure surface and how instability may initiate and evolve with changes in pore water conditions. Quantitative assessments applying the new LFS field method to slopes under infiltration conditions demonstrate that the LFS has the potential to overcome several major limitations in the classical FS methodologies such as the shape of the failure surface and the inherent underestimation of slope instability. Comparison with infiniteslope methods, including a recent extension to variably saturated conditions, shows further enhancement in assessing shallow landslide occurrence using the LFS methodology. Although we use only a linear elastic solution for the state of stress with no postfailure analysis that require more sophisticated elastoplastic or other theories, the LFS provides a new means to quantify the potential instability zones in hillslopes under variably saturated conditions using stressfield based methods.

Finite Element analyses of soil bioengineered slopes
NASA Astrophysics Data System (ADS)
Tamagnini, Roberto; Switala, Barbara Maria; Sudan Acharya, Madhu; Wu, Wei; Graf, Frank; Auer, Michael; te Kamp, Lothar
20140501
Soil Bioengineering methods are not only effective from an economical point of view, but they are also interesting as fully ecological solutions. The presented project is aimed to define a numerical model which includes the impact of vegetation on slope stability, considering both mechanical and hydrological effects. In this project, a constitutive model has been developed that accounts for the multiphase nature of the soil, namely the partly saturated condition and it also includes the effects of a biological component. The constitutive equation is implemented in the Finite Element (FE) software ComesGeo with an implicit integration scheme that accounts for the collapse of the soils structure due to wetting. The mathematical formulation of the constitutive equations is introduced by means of thermodynamics and it simulates the growth of the biological system during the time. The numerical code is then applied in the analysis of an ideal rainfall induced landslide. The slope is analyzed for vegetated and nonvegetated conditions. The final results allow to quantitatively assessing the impact of vegetation on slope stability. This allows drawing conclusions and choosing whenever it is worthful to use soil bioengineering methods in slope stabilization instead of traditional approaches. The application of the FE methods show some advantages with respect to the commonly used limit equilibrium analyses, because it can account for the real coupled straindiffusion nature of the problem. The mechanical strength of roots is in fact influenced by the stress evolution into the slope. Moreover, FE method does not need a predefinition of any failure surface. FE method can also be used in monitoring the progressive failure of the soil bioengineered system as it calculates the amount of displacements and strains of the model slope. The preliminary study results show that the formulated equations can be useful for analysis and evaluation of different soil bio

Jibson, Randall W.; Jibson, Matthew W.
20030101
Landslides typically cause a large proportion of earthquake damage, and the ability to predict slope performance during earthquakes is important for many types of seismichazard analysis and for the design of engineered slopes. Newmark's method for modeling a landslide as a rigidplastic block sliding on an inclined plane provides a useful method for predicting approximate landslide displacements. Newmark's method estimates the displacement of a potential landslide block as it is subjected to earthquake shaking from a specific strongmotion record (earthquake accelerationtime history). A modification of Newmark's method, decoupled analysis, allows modeling landslides that are not assumed to be rigid blocks. This openfile report is available on CDROM and contains Java programs intended to facilitate performing both rigorous and simplified Newmark slidingblock analysis and a simplified model of decoupled analysis. For rigorous analysis, 2160 strongmotion records from 29 earthquakes are included along with a search interface for selecting records based on a wide variety of record properties. Utilities are available that allow users to add their own records to the program and use them for conducting Newmark analyses. Also included is a document containing detailed information about how to use Newmark's method to model dynamic slope performance. This program will run on any platform that supports the Java Runtime Environment (JRE) version 1.3, including Windows, Mac OSX, Linux, Solaris, etc. A minimum of 64 MB of available RAM is needed, and the fully installed program requires 400 MB of disk space.

Curtis L. VanderSchaaf; Harold E. Burkhart
20100101
Maximum sizedensity relationships (MSDR) provide natural resource managers useful information about the relationship between tree density and average tree size. Obtaining a valid estimate of how maximum tree density changes as average tree size changes is necessary to accurately describe these relationships. This paper examines three methods to estimate the slope of...

Integrating concepts and skills: Slope and kinematics graphs
NASA Astrophysics Data System (ADS)
Tonelli, Edward P., Jr.
The concept of force is a foundational idea in physics. To predict the results of applying forces to objects, a student must be able to interpret data representing changes in distance, time, speed, and acceleration. Comprehension of kinematics concepts requires students to interpret motion graphs, where rates of change are represented as slopes of line segments. Studies have shown that majorities of students who show proficiency with mathematical concepts fail accurately to interpret motion graphs. The primary aim of this study was to examine how students apply their knowledge of slope when interpreting kinematics graphs. To answer the research questions a mixed methods research design, which included a survey and interviews, was adopted. Ninety eight (N=98) high school students completed surveys which were quantitatively analyzed along with qualitative information collected from interviews of students (N=15) and teachers ( N=2). The study showed that students who recalled methods for calculating slopes and speeds calculated slopes accurately, but calculated speeds inaccurately. When comparing the slopes and speeds, most students resorted to calculating instead of visual inspection. Most students recalled and applied memorized rules. Students who calculated slopes and speeds inaccurately failed to recall methods of calculating slopes and speeds, but when comparing speeds, these students connected the concepts of distance and time to the line segments and the rates of change they represented. This study's findings will likely help mathematics and science educators to better assist their students to apply their knowledge of the definition of slope and skills in kinematics concepts.

A new method to identify the foot of continental slope based on an integrated profile analysis
NASA Astrophysics Data System (ADS)
Wu, Ziyin; Li, Jiabiao; Li, Shoujun; Shang, Jihong; Jin, Xiaobin
20170601
A new method is proposed to identify automatically the foot of the continental slope (FOS) based on the integrated analysis of topographic profiles. Based on the extremum points of the second derivative and the DouglasPeucker algorithm, it simplifies the topographic profiles, then calculates the second derivative of the original profiles and the DP profiles. Seven steps are proposed to simplify the original profiles. Meanwhile, multiple identification methods are proposed to determine the FOS points, including gradient, water depth and second derivative values of data points, as well as the concave and convex, continuity and segmentation of the topographic profiles. This method can comprehensively and intelligently analyze the topographic profiles and their derived slopes, second derivatives and DP profiles, based on which, it is capable to analyze the essential properties of every single data point in the profile. Furthermore, it is proposed to remove the concave points of the curve and in addition, to implement six FOS judgment criteria.

A method of measuring rainfall on windy slopes
G. L. Hayes
19440101
The object of precipitation measurement, as stated by Brooks (1), is to obtain "a fair sample of the fall reaching the earth's surface over the area represented by the measurement." The area referred to is horizontal, or map area. Even when measured on a slope, precipitation is always expressed as depth of water on a horizontal area.

Slope stabilization guide for Minnesota local government engineers.
DOT National Transportation Integrated Search
20170601
This user guide provides simple, costeffective methods for stabilizing locally maintained slopes along roadways in Minnesota. Eight slope stabilization techniques are presented that local government engineers can undertake using locally available ...

NASA Astrophysics Data System (ADS)
Seto, Shuji; Takahara, Teruyoshi; Kinosh*ta, Atsuhiko; Mizuno, Hideaki; Kawato, Katsushi; Okumura, Minoru; Kageura, Ryouta
20170401
In Japan, at Ontake volcano in 1984 and Kurikoma volcano in 2008, parts of the volcanoes collapsed and largescale sedimentrelated disasters occurred. These disasters were unrelated to volcanic eruption directly. We conducted the case studies by using the airborne electromagnetic surveys to investigate the slopes likely to induce landslides on such volcanoes. The airborne electromagnetic surveys are the effective exploration tool when we investigate in extreme environments that person can't enter and it's necessary to investigate with wide range by a short time. The surveys were conducted by using a helicopter carrying the survey instruments; this method of noncontact investigation acquires resistivity data by the electromagnetic induction. In Japan, the surveys were conducted of 15 active volcanoes where volcanic disasters could have serious social implications. These cases focused on the seeking for the possible slopes that landslides would occur. However, the depth of the slope failure was not evaluated. Therefore in the study, we proposed a new method to determine the potential depth of slope failure. First, we categorized the three characteristics as the cap rock type, the extended collapse type, and the landslide type on the basis of collapsed cases and paid attention to the slope of the cap rock type and also defined the collapse range based on the topography and geological properties. Second, we analyzed resistivity structure about collapsed cases with the differential filter and made clear that collapse occurred in the depth which resistivity suddenly changes. In other volcanoes, we could estimate failure depth by extracting the part which resistivity suddenly changes. In the study, we use the three volcanoes as the main cases, Hokkaido Komagatake, Asama Volcano, and Ontake volcano.

Determination Of Slope Instability Using Spatially Integrated Mapping Framework
NASA Astrophysics Data System (ADS)
Baharuddin, I. N. Z.; Omar, R. C.; Roslan, R.; Khalid, N. H. N.; Hanifah, M. I. M.
20161101
The determination and identification of slope instability are often rely on data obtained from insitu soil investigation work where it involves the logistic of machineries and manpower, thus these aspects may increase the cost especially for remote locations. Therefore a method, which is able to identify possible slope instability without frequent ground walkabout survey, is needed. This paper presents the method used in prediction of slope instability using spatial integrated mapping framework which applicable for remote areas such as tropical forest and natural hilly terrain. Spatial data such as geology, topography, land use map, slope angle and elevation were used in regional analysis during desktop study. Through this framework, the occurrence of slope instability was able to be identified and was validate using a confirmatory site specific analysis.

Gifford, Katherine A; Phillips, Jeffrey S; Samuels, Lauren R; Lane, Elizabeth M; Bell, Susan P; Liu, Dandan; Hohman, Timothy J; Romano, Raymond R; Fritzsche, Laura R; Lu, Zengqi; Jefferson, Angela L
20150701
A symptom of mild cognitive impairment (MCI) and Alzheimer's disease (AD) is a flat learning profile. Learning slope calculation methods vary, and the optimal method for capturing neuroanatomical changes associated with MCI and early AD pathology is unclear. This study crosssectionally compared four different learning slope measures from the Rey Auditory Verbal Learning Test (simple slope, regressionbased slope, twoslope method, peak slope) to structural neuroimaging markers of early AD neurodegeneration (hippocampal volume, cortical thickness in parahippocampal gyrus, precuneus, and lateral prefrontal cortex) across the cognitive aging spectrum [normal control (NC); (n=198; age=76±5), MCI (n=370; age=75±7), and AD (n=171; age=76±7)] in ADNI. Within diagnostic group, general linear models related slope methods individually to neuroimaging variables, adjusting for age, sex, education, and APOE4 status. Among MCI, better learning performance on simple slope, regressionbased slope, and late slope (Trial 25) from the twoslope method related to larger parahippocampal thickness (all pvalues<.01) and hippocampal volume (p<.01). Better regressionbased slope (p<.01) and late slope (p<.01) were related to larger ventrolateral prefrontal cortex in MCI. No significant associations emerged between any slope and neuroimaging variables for NC (pvalues ≥.05) or AD (pvalues ≥.02). Better learning performances related to larger medial temporal lobe (i.e., hippocampal volume, parahippocampal gyrus thickness) and ventrolateral prefrontal cortex in MCI only. Regressionbased and late slope were most highly correlated with neuroimaging markers and explained more variance above and beyond other common memory indices, such as total learning. Simple slope may offer an acceptable alternative given its ease of calculation.

Extension of the ratio method to low energy
Colomer, Frederic; Capel, Pierre; Nunes, F. M.; ...
20160525
The ratio method has been proposed as a means to remove the reaction model dependence in the study of halo nuclei. Originally, it was developed for higher energies but given the potential interest in applying the method at lower energy, in this work we explore its validity at 20 MeV/nucleon. The ratio method takes the ratio of the breakup angular distribution and the summed angular distribution (which includes elastic, inelastic and breakup) and uses this observable to constrain the features of the original halo wave function. In this work we use the Continuum Discretized Coupled Channel method and the Coulombcorrectedmore» Dynamical Eikonal Approximation for the study. We study the reactions of 11Be on 12C, 40Ca and 208Pb at 20 MeV/nucleon. We compare the various theoretical descriptions and explore the dependence of our result on the coretarget interaction. Lastly, our study demonstrates that the ratio method is valid at these lower beam energies.«less

Emerson, Douglas G.; Vecchia, Aldo V.; Dahl, Ann L.
20050101
The drainagearea ratio method commonly is used to estimate streamflow for sites where no streamflow data were collected. To evaluate the validity of the drainagearea ratio method and to determine if an improved method could be developed to estimate streamflow, a multipleregression technique was used to determine if drainage area, main channel slope, and precipitation were significant variables for estimating streamflow in the Red River of the North Basin. A separate regression analysis was performed for streamflow for each of three seasons winter, spring, and summer. Drainage area and summer precipitation were the most significant variables. However, the regression equations generally overestimated streamflows for North Dakota stations and underestimated streamflows for Minnesota stations. To correct the bias in the residuals for the two groups of stations, indicator variables were included to allow both the intercept and the coefficient for the logarithm of drainage area to depend on the group. Drainage area was the only significant variable in the revised regression equations. The exponents for the drainagearea ratio were 0.85 for the winter season, 0.91 for the spring season, and 1.02 for the summer season.

NASA Astrophysics Data System (ADS)
Scalia, C.; Leone, F.; Gangi, M.; Giarrusso, M.; Stift, M. J.
20171201
One method for the determination of integrated longitudinal stellar fields from lowresolution spectra is the socalled slope method, which is based on the regression of the Stokes V signal against the first derivative of Stokes I. Here we investigate the possibility of extending this technique to measure the magnetic fields of cool stars from highresolution spectra. For this purpose we developed a multiline modification to the slope method, called the multiline slope method. We tested this technique by analysing synthetic spectra computed with the COSSAM code and real observations obtained with the highresolution spectropolarimeters Narval, HARPSpol and the Catania Astrophysical Observatory Spectropolarimeter (CAOS). We show that the multiline slope method is a fast alternative to the least squares deconvolution technique for the measurement of the effective magnetic fields of cool stars. Using a Fourier transform on the effective magnetic field variations of the star ε Eri, we find that the longterm periodicity of the field corresponds to the 2.95yr period of the stellar dynamo, revealed by the variation of the activity index.

Verification of the GISbased Newmark method through 2D dynamic modelling of slope stability
NASA Astrophysics Data System (ADS)
Torgoev, A.; Havenith, H.B.
20120401
The goal of this work is to verify the simplified GISbased Newmark displacement approach through 2D dynamic modelling of slope stability. The research is applied to a landslideprone area in Central Asia, the MailuuSuu Valley, situated in the south of Kyrgyzstan. The comparison is carried out on the basis of 30 different profiles located in the target area, presenting different geological, tectonic and morphological settings. One part of the profiles were selected within landslide zones, the other part was selected in stable areas. Many of the landslides are complex slope failures involving falls, rotational sliding and/or planar sliding and flows. These input data were extracted from a 3D structural geological model built with the GOCAD software. Geophysical and geomechanical parameters were defined on the basis of results obtained by multiple surveys performed in the area over the past 15 years. These include geophysical investigation, seismological experiments and ambient noise measurements. Dynamic modelling of slope stability is performed with the UDEC version 4.01 software that is able to compute deformation of discrete elements. Inside these elements both elastoplastic and purely elastic materials (similar to rigid blocks) were tested. Various parameter variations were tested to assess their influence on the final outputs. And even though no groundwater flow was included, the numerous simulations are very timeconsuming (20 mins per model for 10 secs simulated shaking)  about 500 computation hours have been completed so far (more than 100 models). Preliminary results allow us to compare Newmark displacements computed using different GIS approaches (Jibson et al., 1998; Miles and Ho, 1999, among others) with the displacements computed using the original Newmark method (Newmark, 1965, here simulated seismograms were used) and displacements produced along joints by the corresponding 2D dynamical models. The generation of seismic amplification and its impact
 «
 2
 3
 4
 5
 6
 »
 «
 3
 4
 5
 6
 7
 »

Measuring coherence of computerassisted likelihood ratio methods.
Haraksim, Rudolf; Ramos, Daniel; Meuwly, Didier; Berger, Charles E H
20150401
Measuring the performance of forensic evaluation methods that compute likelihood ratios (LRs) is relevant for both the development and the validation of such methods. A framework of performance characteristics categorized as primary and secondary is introduced in this study to help achieve such development and validation. Groundtruth labelled fingerprint data is used to assess the performance of an example likelihood ratio method in terms of those performance characteristics. Discrimination, calibration, and especially the coherence of this LR method are assessed as a function of the quantity and quality of the trace fingerprint specimen. Assessment of the coherence revealed a weakness of the comparison algorithm in the computerassisted likelihood ratio method used. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Rock mass characterisation and stability analyses of excavated slopes
NASA Astrophysics Data System (ADS)
Zangerl, Christian; Lechner, Heidrun
20160401
Excavated slopes in fractured rock masses are frequently designed for open pit mining, quarries, buildings, highways, railway lines, and canals. These slopes can reach heights of several hundreds of metres and in cases concerning open pit mines slopes larger than 1000 m are not uncommon. Given that deepseated slope failures can cause large damage or even loss of life, the slope design needs to incorporate sufficient stability. Thus, slope design methods based on comprehensive approaches need to be applied. Excavation changes slope angle, groundwater flow, and blasting increases the degree of rock mass fracturing as well as rock mass disturbance. As such, excavation leads to considerable stress changes in the slopes. Generally, slope design rely on the concept of factor of safety (FOS), often a requirement by international or national standards. A limitation of the factor of safety is that time dependent failure processes, stressstrain relationships, and the impact of rock mass strain and displacement are not considered. Usually, there is a difficulty to estimate the strength of the rock mass, which in turn is controlled by an interaction of intact rock and discontinuity strength. In addition, knowledge about insitu stresses for the failure criterion is essential. Thus, the estimation of the state of stress of the slope and the strength parameters of the rock mass is still challenging. Given that, largescale insitu testing is difficult and costly, backcalculations of case studies in similar rock types or rock mass classification systems are usually the methods of choice. Concerning backcalculations, often a detailed and standardised documentation is missing, and a direct applicability to new projects is not always given. Concerning rock mass classification systems, it is difficult to consider rock mass anisotropy and thus the empirical estimation of the strength properties possesses high uncertainty. In the framework of this study an approach based on

Linear chirped slope profile for spatial calibration in slope measuring deflectometry
DOE Office of Scientific and Technical Information (OSTI.GOV)
Siewert, F., Email: frank.siewert@helmholtzberlin.de; Zeschke, T.; Arnold, T.
20160515
Slope measuring deflectometry is commonly used by the Xray optics community to measure the longspatialwavelength surface figure error of optical components dedicated to guide and focus Xrays under grazing incidence condition at synchrotron and free electron laser beamlines. The best performing instruments of this kind are capable of absolute accuracy on the level of 3050 nrad. However, the exact bandwidth of the measurements, determined at the higher spatial frequencies by the instrument’s spatial resolution, or more generally by the instrument’s modulation transfer function (MTF) is hard to determine. An MTF calibration method based on application of a test surface withmore» a onedimensional (1D) chirped height profile of constant amplitude was suggested in the past. In this work, we propose a new approach to designing the test surfaces with a 2Dchirped topography, specially optimized for MTF characterization of slope measuring instruments. The design of the developed MTF test samples based on the proposed linear chirped slope profiles (LCSPs) is free of the major drawback of the 1D chirped height profiles, where in the slope domain, the amplitude strongly increases with the local spatial frequency of the profile. We provide the details of fabrication of the LCSP samples. The results of first application of the developed test samples to measure the spatial resolution of the BESSYNOM at different experimental arrangements are also presented and discussed.«less

NASA Astrophysics Data System (ADS)
Tazik, E.; Jahantab, Z.; Bakhtiari, M.; Rezaei, A.; Kazem Alavipanah, S.
20141001
Landslides are among the most important natural hazards that lead to modification of the environment. Therefore, studying of this phenomenon is so important in many areas. Because of the climate conditions, geologic, and geomorphologic characteristics of the region, the purpose of this study was landslide hazard assessment using Fuzzy Logic, frequency ratio and Analytical Hierarchy Process method in Dozein basin, Iran. At first, landslides occurred in Dozein basin were identified using aerial photos and field studies. The influenced landslide parameters that were used in this study including slope, aspect, elevation, lithology, precipitation, land cover, distance from fault, distance from road and distance from river were obtained from different sources and maps. Using these factors and the identified landslide, the fuzzy membership values were calculated by frequency ratio. Then to account for the importance of each of the factors in the landslide susceptibility, weights of each factor were determined based on questionnaire and AHP method. Finally, fuzzy map of each factor was multiplied to its weight that obtained using AHP method. At the end, for computing prediction accuracy, the produced map was verified by comparing to existing landslide locations. These results indicate that the combining the three methods Fuzzy Logic, Frequency Ratio and Analytical Hierarchy Process method are relatively good estimators of landslide susceptibility in the study area. According to landslide susceptibility map about 51% of the occurred landslide fall into the high and very high susceptibility zones of the landslide susceptibility map, but approximately 26 % of them indeed located in the low and very low susceptibility zones.

The coupled response to slopedependent basal melting
NASA Astrophysics Data System (ADS)
Little, C. M.; Goldberg, D. N.; Sergienko, O. V.; Gnanadesikan, A.
20091201
Ice shelf basal melting is likely to be strongly controlled by basal slope. If ice shelves steepen in response to intensified melting, it suggests instability in the coupled iceocean system. The dynamic response of ice shelves governs what stable morphologies are possible, and thus the influence of melting on buttressing and grounding line migration. Simulations performed using a 3D ocean model indicate that a simple form of slopedependent melting is robust under more complex oceanographic conditions. Here we utilize this parameterization to investigate the shape and grounding line evolution of ice shelves, using a shallowshelf approximationbased model that includes lateral drag. The distribution of melting substantially affects the shape and aspect ratio of unbuttressed ice shelves. Slopedependent melting thins the ice shelf near the grounding line, reducing velocities throughout the shelf. Sharp ice thickness gradients evolve at high melting rates, yet grounding lines remain static. In foredeepened, buttressed ice shelves, changes in grounding line flux allow two additional options: stable or unstable retreat. Under some conditions, slopedependent melting results in stable configurations even at high melt rates.

NASA Astrophysics Data System (ADS)
RUNG, J.
20131201
In this study, a series of rainfallstability analyses were performed to simulate the failure mechanism and the function of remediation works of the down slope of T16 tower pier, MaoKong gondola (or T16 Slope) at the hillside of Taipei City using twodimensional finite element method. The failure mechanism of T16 Slope was simulated using the rainfall hyetograph of JangMi typhoon in 2008 based on the field investigation data, monitoring data, soil/rock mechanical testing data and detail design plots of remediation works. Eventually, the numerical procedures and various input parameters in the analysis were verified by comparing the numerical results with the field observations. In addition, 48 hrs design rainfalls corresponding to 5, 10, 25 and 50 years return periods were prepared using the 20 years rainfall data of MuZha rainfall observation station, Central Weather Bureau for the rainfallstability analyses of T16 Slope to inspect the effect of the compound stabilization works on the overall stability of the slope. At T16 Slope, without considering the longitudinal and transverse drainages on the ground surface, there totally 4 types of stabilization works were installed to stabilize the slope. From the slope top to the slope toe, the stabilization works of T16 Slope consists of RCretaining wall with micropile foundation at the upsegment, earth anchor at the upmiddlesegment, soil nailing at the middlesegment and retaining pile at the downsegment of the slope. The effect of each individual stabilization work on the slope stability under rainfall condition was examined and evaluated by raising field groundwater level.

Effect of Soil Roughness on Overland Flow Connectivity at Different Slope Scenarios
NASA Astrophysics Data System (ADS)
Penuela Fernandez, A.; Javaux, M.; Bielders, C.
20131201
Runoff generation, which involves the gradual depression filling and connection of overflowing depressions, is affected by surface roughness and slope. Therefore, quantifying and understanding the effects of surface roughness and slope on overland flow connectivity at the subgrid scale can potentially improve current hydrological modeling and runoff prediction. However, little work has been conducted on quantifying these effects. This study examines the role of surface roughness on overland flow connectivity at the plot scale at different slopes. For this purpose, standard multiGaussian synthetic fields (6 × 6 m) with contrasting surface roughnesses, as defined by the parameters of the variogram (sill and range) of surface elevation, were used. In order to quantify the effects of soil roughness and slope on overland flow connectivity a functional connectivity indicator, socalled the Relative Surface Connection function (Antoine et al., 2009), was applied. This indicator, that represents the ratio of area connected to the outflow boundary (C) in function of the depression storage (DS), is able to capture runoffrelevant connectivity properties. Three parameters characterizing the connectivity function were used to quantify the effects of roughness and slope. These parameters are: C at DS = 0 (CDS=0), connectivity threshold (CT) and maximum depression storage (MDS). Results showed that variations on soil roughness and slope greatly affect the three parameters showing in some cases a clear relationship between structural connectivity and functional connectivity, such as between the ratio sill/range and MDS and between CDS=0 and range. This relationship, described by mathematical expressions, not only allows the quantification and comparison of the effects of soil roughness and slope in overland flow connectivity but also the prediction of these effects by the study of the variogram.

Balogh, A. L.; Petak, F.; Fodor, G. H.; Tolnai, J.; Csorba, Z.; Babik, B.
20160101
Background Capnography may provide useful noninvasive bedside information concerning heterogeneity in lung ventilation, ventilation–perfusion mismatching and metabolic status. Although the capnogram may be recorded by mainstream and sidestream techniques, the capnogram indices furnished by these approaches have not previously been compared systematically. Methods Simultaneous mainstream and sidestream time and volumetric capnography was performed in anaesthetized, mechanically ventilated patients undergoing elective heart surgery. Time capnography was used to assess the phase II (SII,T) and III slopes (SIII,T). The volumetric method was applied to estimate phase II (SII,V) and III slopes (SIII,V), together with the dead space values according to the Fowler (VDF), Bohr (VDB), and Enghoff (VDE) methods and the volume of CO2 eliminated per breath (VCO2). The partial pressure of endtidal CO2 (PETCO2) was registered. Results Excellent correlation and good agreement were observed in SIII,T measured by the mainstream and sidestream techniques [ratio=1.05 (sem 0.16), R2=0.92, P<0.0001]. Although the sidestream technique significantly underestimated VCO2 and overestimated SIII,V [1.32 (0.28), R2=0.93, P<0.0001], VDF, VDB, and VDE, the agreement between the mainstream and sidestream techniques in the difference between VDE and VDB, reflecting the intrapulmonary shunt, was excellent [0.97 (0.004), R2=0.92, P<0.0001]. The PETCO2 exhibited good correlation and mild differences between the mainstream and sidestream approaches [0.025 (0.005) kPa]. Conclusions Sidestream capnography provides adequate quantitative bedside information about uneven alveolar emptying and ventilation–perfusion mismatching, because it allows reliable assessments of the phase III slope, PETCO2 and intrapulmonary shunt. Reliable measurement of volumetric parameters (phase II slope, dead spaces, and eliminated CO2 volumes) requires the application of a mainstream device. PMID:27317710

Characterization of Unstable Rock Slopes Through Passive Seismic Measurements
NASA Astrophysics Data System (ADS)
Kleinbrod, Ulrike; Burjánek, Jan; Fäh, Donat
20140501
Catastrophic rock slope failures have high social impact, causing significant damage to infrastructure and many casualties throughout the world each year. Both detection and characterization of rock instabilities are therefore of key importance. Analysing unstable rock slopes by means of ambient vibrations might be a new alternative to the already existing methods as for example geotechnical displacement measurements. A systematic measurement campaign has been initiated recently in Switzerland in order to study the seismic response of potential rockslides concerning a broad class of slope failure mechanisms and material conditions. First results are presented in this contribution. Small aperture seismic arrays were deployed at sites of interest for a short period of time (several hours) in order to record ambient vibrations. During each measurement a reference station was installed on a stable part close to the instability. The total number of stations used varies from 16 down to 2, depending on the site scope and resource availability. Instable rock slopes show a highly directional ground motion which is significantly amplified with respect to stable areas. These effects are strongest at certain frequencies which are identified as eigenfrequencies of the unstable rock mass. The eigenfrequencies and predominant directions have been estimated by frequency dependent polarization analysis. Sitetoreference spectral ratios have been calculated as well in order to estimate the relative amplification of ground motion at unstable parts. The retrieved results were compared with independent insitu observations and other available data. The directions of maximum amplification are in most cases perpendicular to open cracks mapped on the surface and in good agreement with the deformation directions obtained by geodetic measurements. The interpretation of the observed wave field is done through numerical modelling of seismic wave propagation in fractured media with complex

A Hybrid FEMANN Approach for Slope Instability Prediction
NASA Astrophysics Data System (ADS)
Verma, A. K.; Singh, T. N.; Chauhan, Nikhil Kumar; Sarkar, K.
20160901
Assessment of slope stability is one of the most critical aspects for the life of a slope. In any slope vulnerability appraisal, Factor Of Safety (FOS) is the widely accepted index to understand, how close or far a slope from the failure. In this work, an attempt has been made to simulate a road cut slope in a landslide prone area in Rudrapryag, Uttarakhand, India which lies near Himalayan geodynamic mountain belt. A combination of Finite Element Method (FEM) and Artificial Neural Network (ANN) has been adopted to predict FOS of the slope. In ANN, a three layer, feed forward backpropagation neural network with one input layer and one hidden layer with three neurons and one output layer has been considered and trained using datasets generated from numerical analysis of the slope and validated with new set of field slope data. Mean absolute percentage error estimated as 1.04 with coefficient of correlation between the FOS of FEM and ANN as 0.973, which indicates that the system is very vigorous and fast to predict FOS for any slope.

NASA Astrophysics Data System (ADS)
Ersöz, Timur; Topal, Tamer
20170401
Rocks containing pore spaces, fractures, joints, bedding planes and faults are prone to weathering due to temperature differences, wettingdrying, chemistry of solutions absorbed, and other physical and chemical agents. Especially cut slopes are very sensitive to weathering activities because of disturbed rock mass and topographical condition by excavation. During and right after an excavation process of a cut slope, weathering and erosion may act on this newly exposed rock material. These acting on the material may degrade and change its properties and the stability of the cut slope in its engineering lifetime. In this study, the effect of physical and chemical weathering agents on shear strength parameters of the rocks are investigated in order to observe the differences between weathered and unweathered rocks. Also, slope stability assessment of cut slopes affected by these weathering agents which may disturb the parameters like strength, cohesion, internal friction angle, unit weight, water absorption and porosity are studied. In order to compare the condition of the rock materials and analyze the slope stability, the parameters of weathered and fresh rock materials are found with insitu tests such as Schmidt hammer and laboratory tests like uniaxial compressive strength, point load and direct shear. Moreover, slake durability and methylene blue tests are applied to investigate the response of the rock to weathering and presence of clays in rock materials, respectively. In addition to these studies, both rock strength parameters and any kind of failure mechanism are determined by probabilistic approach with the help of SSPC system. With these observations, the performances of the weathered and fresh zones of the cut slopes are evaluated and 2D slope stability analysis are modeled with further recommendations for the cut slopes. Keywords: 2D Modeling, Rock Strength, Slope Stability, SSPC, Weathering

Slope Estimation in Noisy Piecewise Linear Functions✩
Ingle, Atul; Bucklew, James; Sethares, William; Varghese, Tomy
20140101
This paper discusses the development of a slope estimation algorithm called MAPSlope for piecewise linear data that is corrupted by Gaussian noise. The number and locations of slope change points (also known as breakpoints) are assumed to be unknown a priori though it is assumed that the possible range of slope values lies within known bounds. A stochastic hidden Markov model that is general enough to encompass real world sources of piecewise linear data is used to model the transitions between slope values and the problem of slope estimation is addressed using a Bayesian maximum a posteriori approach. The set of possible slope values is discretized, enabling the design of a dynamic programming algorithm for posterior density maximization. Numerical simulations are used to justify choice of a reasonable number of quantization levels and also to analyze mean squared error performance of the proposed algorithm. An alternating maximization algorithm is proposed for estimation of unknown model parameters and a convergence result for the method is provided. Finally, results using data from political science, finance and medical imaging applications are presented to demonstrate the practical utility of this procedure. PMID:25419020

Slope Estimation in Noisy Piecewise Linear Functions.
Ingle, Atul; Bucklew, James; Sethares, William; Varghese, Tomy
20150301
This paper discusses the development of a slope estimation algorithm called MAPSlope for piecewise linear data that is corrupted by Gaussian noise. The number and locations of slope change points (also known as breakpoints) are assumed to be unknown a priori though it is assumed that the possible range of slope values lies within known bounds. A stochastic hidden Markov model that is general enough to encompass real world sources of piecewise linear data is used to model the transitions between slope values and the problem of slope estimation is addressed using a Bayesian maximum a posteriori approach. The set of possible slope values is discretized, enabling the design of a dynamic programming algorithm for posterior density maximization. Numerical simulations are used to justify choice of a reasonable number of quantization levels and also to analyze mean squared error performance of the proposed algorithm. An alternating maximization algorithm is proposed for estimation of unknown model parameters and a convergence result for the method is provided. Finally, results using data from political science, finance and medical imaging applications are presented to demonstrate the practical utility of this procedure.

NASA Astrophysics Data System (ADS)
Reid, M. E.; Iverson, R. M.; Brien, D. L.; Iverson, N. R.; Lahusen, R. G.; Logan, M.
20041201
Most studies of landslide initiation employ limit equilibrium analyses of slope stability. Owing to a lack of detailed data, however, few studies have tested limitequilibrium predictions against physical measurements of slope failure. We have conducted a series of fieldscale, highly controlled landslide initiation experiments at the USGS debrisflow flume in Oregon; these experiments provide exceptional data to test limit equilibrium methods. In each of seven experiments, we attempted to induce failure in a 0.65m thick, 2m wide, 6m3 prism of loamy sand placed behind a retaining wall in the 31° sloping flume. We systematically investigated triggering of sliding by groundwater injection, by prolonged moderateintensity sprinkling, and by bursts of high intensity sprinkling. We also used vibratory compaction to control soil porosity and thereby investigate differences in failure behavior of dense and loose soils. About 50 sensors were monitored at 20 Hz during the experiments, including nests of tiltmeters buried at 7 cm spacing to define subsurface failure geometry, and nests of tensiometers and porepressure sensors to define evolving porepressure fields. In addition, we performed ancillary laboratory tests to measure soil porosity, shear strength, hydraulic conductivity, and compressibility. In loose soils (porosity of 0.52 to 0.55), abrupt failure typically occurred along the flume bed after substantial soil deformation. In denser soils (porosity of 0.41 to 0.44), gradual failure occurred within the soil prism. All failure surfaces had a maximum length to depth ratio of about 7. In even denser soil (porosity of 0.39), we could not induce failure by sprinkling. The internal friction angle of the soils varied from 28° to 40° with decreasing porosity. We analyzed stability at failure, given the observed porepressure conditions just prior to large movement, using a 1D infiniteslope method and a more complete 2D Janbu method. Each method provides a static

North Slope (Wahluke Slope) expedited response action cleanup plan
DOE Office of Scientific and Technical Information (OSTI.GOV)
Not Available
The purpose of this action is to mitigate any threat to public health and the environment from hazards on the North Slope and meet the expedited response action (ERA) objective of cleanup to a degree requiring no further action. The ERA may be the final remediation of the 100I3 Operable Unit. A No Action record of decision (ROD) may be issued after remediation completion. The US Department of Energy (DOE) currently owns or administers approximately 140 mi{sup 2} (about 90,000 acres) of land north and east of the Columbia River (referred to as the North Slope) that is part ofmore» the Hanford Site. The North Slope, also commonly known as the Wahluke Slope, was not used for plutonium production or support facilities; it was used for military air defense of the Hanford Site and vicinity. The North Slope contained seven antiaircraft gun emplacements and three NikeAjax missile positions. These military positions were vacated in 19601961 as the defense requirements at Hanford changed. They were demolished in 1974. Prior to government control in 1943, the North Slope was homesteaded. Since the initiation of this ERA in the summer of 1992, DOE signed the modified Hanford Federal Agreement and Consent Order (TriParty Agreement) with the Washington Department of Ecology (Ecology) and the US Environmental Protection Agency (EPA), in which a milestone was set to complete remediation activities and a draft closeout report by October 1994. Remediation activities will make the North Slope area available for future nonDOE uses. Thirtynine sites have undergone limited characterization to determine if significant environmental hazards exist. This plan documents the results of that characterization and evaluates the potential remediation alternatives.«less

Hortness, J.E.
20040101
The U.S. Geological Survey (USGS) measures discharge in streams using several methods. However, measurement of peak discharges is often impossible or impractical due to difficult access, inherent danger of making measurements during flood events, and timing often associated with flood events. Thus, many peak discharge values often are calculated after the fact by use of indirect methods. The most common indirect method for estimating peak dis charges in streams is the slopearea method. This, like other indirect methods, requires measuring the flood profile through detailed surveys. Processing the survey data for efficient entry into computer streamflow models can be time demanding; SAM 2.1 is a program designed to expedite that process. The SAM 2.1 computer program is designed to be run in the field on a portable computer. The program processes digital surveying data obtained from an electronic surveying instrument during slope area measurements. After all measurements have been completed, the program generates files to be input into the SAC (SlopeArea Computation program; Fulford, 1994) or HECRAS (Hydrologic Engineering CenterRiver Analysis System; Brunner, 2001) computer streamflow models so that an estimate of the peak discharge can be calculated.

NASA Astrophysics Data System (ADS)
Nayamatullah, M.; Rao Pillalamarri, Narasimha; Bhaganagar, Kiran
20180401
A numerical investigation was performed to understand the flow dynamics of 2D density currents over sloping surfaces. Large eddy simulation was conducted for lockexchange (LE) release currents and overflows. 2D NavierStokes equations were solved using the Boussinesq approximation. The effects of the lock aspectratio (height/length of lock), slope, and Reynolds number on the flow structures and turbulence mixing have been analyzed. Results have confirmed buoyancy within the head of the twodimensional currents is not conserved which contradicts the classical thermal theory. The lock aspectratio dictates the fraction of initial buoyancy which is carried by the head of the current at the beginning of the slumping (horizontal) and accelerating phase (over a slope), which has important implications on turbulence kinetic energy production, and hence mixing in the current. For LE flows over a slope, increasing slope angle enhances the turbulence production. Increasing slope results in shear reversal within the density current resulting in shearinstabilities. Differences in turbulence production mechanisms and flow structures exist between the LE and constantflux release currents resulting in significant differences in the flow characteristics between different releases.

Automated Measurement of PatientSpecific Tibial Slopes from MRI
Amerinatanzi, Amirhesam; Summers, Rodney K.; Ahmadi, Kaveh; Goel, Vijay K.; Hewett, Timothy E.; Nyman, Edward
20170101
Background: Multiplanar proximal tibial slopes may be associated with increased likelihood of osteoarthritis and anterior cruciate ligament injury, due in part to their role in checking the anteriorposterior stability of the knee. Established methods suffer repeatability limitations and lack computational efficiency for intuitive clinical adoption. The aims of this study were to develop a novel automated approach and to compare the repeatability and computational efficiency of the approach against previously established methods. Methods: Tibial slope geometries were obtained via MRI and measured using an automated Matlabbased approach. Data were compared for repeatability and evaluated for computational efficiency. Results: Mean lateral tibial slope (LTS) for females (7.2°) was greater than for males (1.66°). Mean LTS in the lateral concavity zone was greater for females (7.8° for females, 4.2° for males). Mean medial tibial slope (MTS) for females was greater (9.3° vs. 4.6°). Along the medial concavity zone, female subjects demonstrated greater MTS. Conclusion: The automated method was more repeatable and computationally efficient than previously identified methods and may aid in the clinical assessment of knee injury risk, inform surgical planning, and implant design efforts. PMID:28952547

NASA Astrophysics Data System (ADS)
Goswami, A.; Olson, P. L.; Hinnov, L. A.; Gnanadesikan, A.
20150401
We present a method for reconstructing global ocean bathymetry that uses a plate cooling model for the oceanic lithosphere, the age distribution of the oceanic crust, global oceanic sediment thicknesses, plus shelfsloperise structures calibrated at modern active and passive continental margins. Our motivation is to reconstruct realistic ocean bathymetry based on parameterized relationships of presentday variables that can be applied to global oceans in the geologic past, and to isolate locations where anomalous processes such as mantle convection may affect bathymetry. Parameters of the plate cooling model are combined with ocean crustal age to calculate depthtobasem*nt. To the depthtobasem*nt we add an isostatically adjusted, multicomponent sediment layer, constrained by sediment thickness in the modern oceans and marginal seas. A continental shelfsloperise structure completes the bathymetry reconstruction, extending from the ocean crust to the coastlines. Shelfsloperise structures at active and passive margins are parameterized using modern ocean bathymetry at locations where a complete history of seafloor spreading is preserved. This includes the coastal regions of the North, South, and Central Atlantic Ocean, the Southern Ocean between Australia and Antarctica, and the Pacific Ocean off the west coast of South America. The final products are global maps at 0.1° × 0.1° resolution of depthtobasem*nt, ocean bathymetry with an isostatically adjusted, multicomponent sediment layer, and ocean bathymetry with reconstructed continental shelfsloperise structures. Our reconstructed bathymetry agrees with the measured ETOPO1 bathymetry at most passive margins, including the east coast of North America, north coast of the Arabian Sea, and northeast and southeast coasts of South America. There is disagreement at margins with anomalous continental shelfsloperise structures, such as around the Arctic Ocean, the Falkland Islands, and Indonesia.

NASA Astrophysics Data System (ADS)
Goswami, A.; Olson, P. L.; Hinnov, L. A.; Gnanadesikan, A.
20150901
We present a method for reconstructing global ocean bathymetry that combines a standard plate cooling model for the oceanic lithosphere based on the age of the oceanic crust, global oceanic sediment thicknesses, plus generalized shelfsloperise structures calibrated at modern active and passive continental margins. Our motivation is to develop a methodology for reconstructing ocean bathymetry in the geologic past that includes heterogeneous continental margins in addition to abyssal ocean floor. First, the plate cooling model is applied to maps of ocean crustal age to calculate depth to basem*nt. To the depth to basem*nt we add an isostatically adjusted, multicomponent sediment layer constrained by sediment thickness in the modern oceans and marginal seas. A threeparameter continental shelfsloperise structure completes the bathymetry reconstruction, extending from the ocean crust to the coastlines. Parameters of the shelfsloperise structures at active and passive margins are determined from modern ocean bathymetry at locations where a complete history of seafloor spreading is preserved. This includes the coastal regions of the North, South, and central Atlantic, the Southern Ocean between Australia and Antarctica, and the Pacific Ocean off the west coast of South America. The final products are global maps at 0.1° × 0.1° resolution of depth to basem*nt, ocean bathymetry with an isostatically adjusted multicomponent sediment layer, and ocean bathymetry with reconstructed continental shelfsloperise structures. Our reconstructed bathymetry agrees with the measured ETOPO1 bathymetry at most passive margins, including the east coast of North America, north coast of the Arabian Sea, and northeast and southeast coasts of South America. There is disagreement at margins with anomalous continental shelfsloperise structures, such as around the Arctic Ocean, the Falkland Islands, and Indonesia.
 «
 3
 4
 5
 6
 7
 »
 «
 4
 5
 6
 7
 8
 »

NASA Astrophysics Data System (ADS)
Deldar, H.; Bidokhti, A. A.; Chegini, V.
20180101
Internal waves usually cause temporal and spatial changes of density and consequently affect the acoustic wave propagation in the ocean. The purpose of this study is a laboratory investigation of the effects of internal waves generated by oscillation of a cylinder in a large stratified glass tank with a sloping bed on the sound waves propagation. Results showed that sound waves are affected by internal waves that depend on the slope angle to the direction of internal wave propagation angle ratio. When the ratio is subcritical or supercritical, the acoustic signal is much reduced as compared to the case with no sloped bottom. This can be explained in terms of the internal waves energy reaching the sloped bed and their reflections.

He, JiJun; Cai, QiangGuo; Liu, SongBo
20120501
Based on the field observation data of runoff and sediment yield produced by single rainfall events in runoff plots, this paper analyzed the variation patterns of runoff and sediment yield on the slopes with different gradients under different single rainfall conditions. The differences in the rainfall conditions had little effects on the variation patterns of slope runoff with the gradient. Under the conditions of six different rainfall events in the study area, the variation patterns of slope runoff with the gradient were basically the same, i. e., the runoff increased with increasing gradient, but the increment of the runoff decreased slightly with increasing gradient, which was mainly determined by the infiltration flux of atmospheric precipitation. Rainfall condition played an important role on the slope sediment yield. Generally, there existed a critical slope gradient for slope erosion, but the critical gradient was not a fixed value, which varied with rainfall condition. The critical slope gradient for slope erosion increased with increasing slope gradient. When the critical slope gradient was greater, the variation of slope sediment yield with slope gradient always became larger.

Delayslopedependent stability results of recurrent neural networks.
Li, Tao; Zheng, Wei Xing; Lin, Chong
20111201
By using the fact that the neuron activation functions are sector bounded and nondecreasing, this brief presents a new method, named the delayslopedependent method, for stability analysis of a class of recurrent neural networks with timevarying delays. This method includes more information on the slope of neuron activation functions and fewer matrix variables in the constructed LyapunovKrasovskii functional. Then some improved delaydependent stability criteria with less computational burden and conservatism are obtained. Numerical examples are given to illustrate the effectiveness and the benefits of the proposed method.

Structural Damage Detection Using Slopes of Longitudinal Vibration Shapes
Xu, W.; Zhu, W. D.; Smith, S. A.; ...
20160318
While structural damage detection based on flexural vibration shapes, such as mode shapes and steadystate response shapes under harmonic excitation, has been well developed, little attention is paid to that based on longitudinal vibration shapes that also contain damage information. This study originally formulates a slope vibration shape for damage detection in bars using longitudinal vibration shapes. To enhance noise robustness of the method, a slope vibration shape is transformed to a multiscale slope vibration shape in a multiscale domain using wavelet transform, which has explicit physical implication, high damage sensitivity, and noise robustness. These advantages are demonstrated in numericalmore» cases of damaged bars, and results show that multiscale slope vibration shapes can be used for identifying and locating damage in a noisy environment. A threedimensional (3D) scanning laser vibrometer is used to measure the longitudinal steadystate response shape of an aluminum bar with damage due to reduced crosssectional dimensions under harmonic excitation, and results show that the method can successfully identify and locate the damage. Slopes of longitudinal vibration shapes are shown to be suitable for damage detection in bars and have potential for applications in noisy environments.«less

20161214
The image shows a region we see many slope streaks, typically dark features on slopes in the equatorial regions on Mars. They may extend for tens of meters in length and gradually fade away with time as new ones form. The most common hypothesis is that they are generated by dust avalanches that regularly occur on steep slopes exposing fresh dark materials from underneath the brighter dust. There are many types of slope streaks but one of the most recent and significant findings using HiRISE was the discovery of a new type called "recurring slope lineae," or RSL for short. Recent studies suggest that RSL may form through the flow of briny (extremely salty) liquid water that can be stable on the surface of Mars even under current climatic conditions for a limited time in summer when it is relatively warm. How can we distinguish between conventional slope streaks like the ones we see here and RSL? There are many criteria. For instance, RSL are usually smaller in size than regular slope streaks. However, one of the most important conditions is seasonal behavior, since RSL appear to be active only in summer while regular slope streaks can be active anytime of the year. This site is monitored regularly by HiRISE scientists because of the high density of slope streaks and their different sizes and orientations. If we look at a timelapse sequence, we will see that a new slope streak has indeed formed in the period since April 2016 (and we can note how dark it is in comparison to the others indicating its freshness). However, this period corresponds mainly to the autumn season in this part of Mars, whereas we do not see any major changes in the summer season. This suggests that the feature that developed is a regular slope streak just like all the others in the area. http://photojournal.jpl.nasa.gov/catalog/PIA21272

Method of fabricating a high aspect ratio microstructure
Warren, John B.
20030506
The present invention is for a method of fabricating a high aspect ratio, freestanding microstructure. The fabrication method modifies the exposure process for SU8, an negativeacting, ultravioletsensitive photoresist used for microfabrication whereby a UVabsorbent glass substrate, chosen for complete absorption of UV radiation at 380 nanometers or less, is coated with a negative photoresist, exposed and developed according to standard practice. This UV absorbent glass enables the fabrication of cylindrical cavities in a negative photoresist microstructures that have aspect ratios of 8:1.

Influence of slope on subtalar pronation in submaximal running performance
de Oliveira, Vinicius Machado; Detoni, Guilherme Cesca; Ferreira, Cristhian; Portela, Bruno Sergio; Queiroga, Marcos Roberto; Tartaruga, Marcus Peikriszwili
20130101
OBJECTIVE : To investigate the slope influence on the maximal subtalar pronation in submaximal running speeds. METHODS : Sixteen endurance runners participated of a running economy (RE) test in a treadmill with different slopes (+1%, +5%, +10%, +15%). For each slope a 4minute run was performed with no rest break for the purpose of measuring the magnitude of kinematic variables by means of a high frequency video camera positioned in a frontalposterior plane of the individual. RESULTS : No significant differences were verified in maximal subtalar pronation between legs and between the slopes adopted, showing that changes of running technique due to modifications of slope aren't enough to modify the behavior of maximum subtalar pronation. CONCLUSION : The subtalar pronation is independent of slope, which may be influenced by other intervening variables. Level of Evidence II, Diagnostic Study PMID:24453662

Mahata, Sasadhar; Bhattacharya, Sourandra K; Wang, ChungHo; Liang, MaoChang
20120915
The oxygen isotopic composition of carbon dioxide originating at the Earth's surface is modified in the stratosphere by interaction with ozone which has anomalous oxygen isotope ratio (Δ(17)O = 1000 * ln(1 + δ(17)O/1000)  0.522 * 1000 * ln (1 + δ(18)O/1000) >0). The inherited anomaly provides a powerful tracer for studying biogeochemical cycles involving CO(2). However, the existing methods are either too imprecise or have difficulty in determining the small Δ(17)O variations found in the tropospheric CO(2). In this study an earlier published CeO(2) and CO(2) exchange method has been modified and improved for measuring the Δ(17)O values of atmospheric carbon dioxide with high precision. The CO(2) fraction from air samples was separated by cryogenic means and purified using gas chromatography. This CO(2) was first analyzed in an isotope ratio mass spectrometer, then artificially equilibrated with hot CeO(2) to alter its oxygen isotopes massdependently and reanalyzed. From these data the (17)O/(16)O and (18)O/(16)O ratios were calculated and the Δ(17)O value was determined. The validity of the method was established in several tests by using artificially prepared CO(2) with zero and nonzero Δ(17)O values. The published value of the CO(2)H(2) O equilibrium slope was also reproduced. The CO(2)CeO(2) equilibration method has been improved to measure the oxygen isotope anomaly (Δ(17)O value) of atmospheric CO(2) with an analytical precision of ±0.12‰ (2σ). Copyright © 2012 John Wiley & Sons, Ltd.

Arctic Submarine Slope Stability
NASA Astrophysics Data System (ADS)
Winkelmann, D.; Geissler, W.
20101201
the consequence. Its geometrical configuration and timing is different from submarine slides on other glaciated continental margins. Thus, it raises the question whether slope stability within the Arctic Ocean is governed by processes specific to this environment. The extraordinary thick slabs (up to 1600 m) that were moved translationally during sliding rise the question on the nature of the weak layers associated with this process. Especially theories involving higher pore pressure are being challenged by this observation, because either extreme pore pressures or alternative explanations (e.g. mineralogical and/or textural) can be considered. To assess the actual submarine slope stability and failure potential in the Arctic Ocean, we propose to drill and recover weak layer material of the HYM from the adjacent intact strata by deep drilling under the framework of Integrated Ocean Drilling Program. This is the only method to recover weak layer material from the HYM, because the strata are too thick. We further propose to drill into the adjacent deforming slope to identify material properties of the layers acting as detachment and monitor the deformation.

Lidar standalone retrieval of atmospheric aerosol microphysical properties during SLOPE
NASA Astrophysics Data System (ADS)
OrtizAmezcua, Pablo; Samaras, Stefanos; Böckmann, Christine; Antonio BenaventOltra, Jose; Luis GuerreroRascado, Juan; Román, Roberto; AladosArboledas, Lucas
20180401
Two cases from SLOPE campaign at Granada are analyzed in terms of particle microphysical properties using novel software developed at Potsdam University. Multiwavelength Raman lidar measurements of particle extinction and backscatter coefficients as well as linear particle depolarization ratios are used as input for the software. The result of the retrieval is a 2dimensional particle volume distribution as a function of radius and aspect ratio, from which the particle microphysical properties are obtained.

NASA Astrophysics Data System (ADS)
Del Gaudio, Vincenzo; Wasowski, Janusz
20160401
In the last few decades, we have witnessed a growing awareness of the role of site dynamic response to seismic shaking in slope failures during earthquakes. Considering the time and costs involved in acquiring accelerometer data on landslide prone slopes, the analysis of ambient noise offers a profitable investigative alternative. Standard procedures of ambient noise analysis, according to the technique known as HVNR or Nakamura's method, were originally devised to interpret data under simple site conditions similar to 1D layering (flat horizontal layering infinitely extended). In such cases, conditions of site amplification, characterized by a strong impedance contrast between a soft surface layer and a stiff bedrock, result in a single pronounced isotropic maximum of spectral ratios between horizontal and vertical component of ambient noise. However, previous studies have shown that the dynamic response of slopes affected by landslides is rather complex, being characterized by multiple resonance peaks with directional variability, thus, the use of standard techniques can encounter difficulties in providing reliable information. A new approach of data analysis has recently been proposed to exploit the potential of information content of Rayleigh waves present in ambient noise, with regard to the identification of frequency and orientation of directional resonance. By exploiting ground motion ellipticity this approach can also provide information on vertical distribution of Swave velocity, which controls site amplification factors. The method, based on the identification of Rayleigh wave packets from instantaneous polarization properties of ambient noise, was first tested using synthetic signals in order to optimize the data processing system. Then the improved processing scheme is adopted to reprocess and reinterpret the ambient noise data acquired on landslide prone slopes around Caramanico Terme (central Italy), at sites monitored also with accelerometer

NASA Astrophysics Data System (ADS)
Shahrestani, Shahed; Mokhtari, Ahmad Reza
20170401
Stream sediment sampling is a wellknown technique used to discover the geochemical anomalies in regional exploration activities. In an upstream catchment basin of stream sediment sample, the geochemical signals originating from probable mineralization could be diluted due to mixing with the weathering material coming from the nonanomalous sources. Hawkes's equation (1976) was an attempt to overcome the problem in which the area size of catchment basin was used to remove dilution from geochemical anomalies. However, the metal content of a stream sediment sample could be linked to several geomorphological, sedimentological, climatic and geological factors. The area size is not itself a comprehensive representative of dilution taking place in a catchment basin. The aim of the present study was to consider a number of geomorphological factors affecting the sediment supply, transportation processes, storage and in general, the geochemistry of stream sediments and their incorporation in the dilution correction procedure. This was organized through employing the concept of sediment yield and sediment delivery ratio and linking such characteristics to the dilution phenomenon in a catchment basin. Main stream slope (MSS), relief ratio (RR) and area size (Aa) of catchment basin were selected as the important proxies (PSDRa) for sediment delivery ratio and then entered to the Hawkes's equation. Then, Hawkes's and new equations were applied on the stream sediment dataset collected from TakhteSoleyman district, west of Iran for Au, As and Sb values. A number of large and small gold, antimony and arsenic mineral occurrences were used to evaluate the results. Anomaly maps based on the new equations displayed improvement in anomaly delineation taking the spatial distribution of mineral deposits into account and could present new catchment basins containing known mineralization as the anomaly class, especially in the case of Au and As. Four catchment basins having Au and As

St Charles, F K; Cook, C J; Clayton, P M
20110201
Cigarette smoke analyte yields are often expressed as ratios relative to tar or nicotine yields, usually to compare different products or to estimate human uptake of smoke in relation to nicotine uptake measurements. The method, however, can lead to distorted interpretations, especially in the case of ratios from ultralow tar yield cigarettes. In brief, as tar yields decrease below the 5–6 mg per cigarette range, the tartonicotine ratio (TNR) decreases rapidly in a nonlinear fashion. If, however, the nicotine yield, rather than the ratio, is plotted versus the tar yield, the nonlinearity disappears and a straight line is obtained, with a slight positive intercept for nicotine on the ordinate. Unlike the ratio, the slope appears to depend only on the concentration of the nicotine in the blend and does not appear to vary with smoking parameters such as puff volume, puff interval or length smoked or with cigarette design parameters such as length, circumference or the amount of filtration or filter ventilation. Therefore, such a slope is analogous to the TNR although, unlike that ratio, it is invariant. Even more simply, the concentration of the nicotine in the blend, at least for American blendstyle cigarettes, provides a similar index.

Assessing slope stability in unplanned settlements in developing countries.
Anderson, Malcolm G; Holcombe, Liz; Renaud, JeanPhilippe
20071001
Unplanned housing in developing countries is often located on steep slopes. Frequently no building code is enforced for such housing and mains water is provided with no drainage provision. Both of these factors can be particularly significant in terms of landslide risk if, as is so often the case, such slopes lack any planned drainage provision. There is thus a need to develop a model that facilitates the assessment of slope stability in an holistic context, incorporating a wide range of factors (including surface cover, soil water topographic convergence, slope loading and point source water leakage) in order that appropriate advice can be given as to the general controls on slope stability in such circ*mstances. This paper outlines a model configured for this specific purpose and describes an application to a site in St. Lucia, West Indies, where there is active slope movement in an unplanned housing development on relatively steep topography. The model findings are in accord with the nature of the current failure at the site, provide guidance as to the significance of slope drainage and correspond to inferences drawn from an application of resistance envelope methods to the site. In being able to scenario test a uniquely wide range of combinations of factors, the model structure is shown to be highly valuable in assessing dominant slope stability process controls in such complex environments.

Impact of vegetation on stability of slopes subjected to rainfall  numerical aspect
NASA Astrophysics Data System (ADS)
Switala, Barbara Maria; Tamagnini, Roberto; Sudan Acharya, Madhu; Wu, Wei
20150401
Recent years brought a significant development of soil bioengineering methods, considered as an ecological and economically effective measure for slope stabilization. This work aims to show the advantages of the soil bioengineering solutions for a slope subjected to a heavy rainfall, with the help of a numerical model, which integrates most of the significant plant and slope features. There are basically two different ways in which vegetation can affect stability of a slope: root reinforcement (mechanical impact) and root water uptake (evapotranspiration). In the numerical model, the first factor is modelled using the CamClay model extended for unsaturated conditions by Tamagnini (2004). The original formulation of a constitutive model is modified by introducing an additional constitutive parameter, which causes an expansion of the yield surface as a consequence of an increase in root mass in a representative soil element. The second factor is the root water uptake, which is defined as a volumetric sink term in the continuity equation of groundwater flow. Water removal from the soil mass causes an increase in suction in the vicinity of the root zone, which leads to an increase in the soil cohesion and provides additional strength to the soilroot composite. The developed numerical model takes into account the above mentioned effects of plants and thus considers the multiphase nature of the soilplantwater relationship. Using the developed method, stability of some vegetated and nonvegetated slopes subjected to rainfall are investigated. The performance of each slope is evaluated by the time at which slope failure occurs. Different slope geometries and soil mechanical and hydrological properties are considered. Comparison of the results obtained from the analyses of vegetated and nonvegetated slopes leads to the conclusion, that the use of soil bioengineering methods for slope stabilization can be effective and can significantly delay the occurrence of a

NASA Astrophysics Data System (ADS)
Hamidine, Mahamadou; Yuan, Xiuhua
20111101
In this article a numerical simulation is carried out on a single channel optical transmission system with channel bit rate greater than 40 Gb/s to investigate optical signal degradation due to the impact of dispersion and dispersion slope of both transmitting and dispersion compensating fibers. By independently varying the input signal power and the dispersion slope of both transmitting and dispersion compensating fibers of an optical link utilizing a channel bit rate of 86 Gb/s, a good quality factor (Q factor) is obtained with a dispersion slope compensation ratio change of +/10% for a faithful transmission. With this ratio change a minimum Q factor of 16 dB is obtained in the presence of amplifier noise figure of 5 dB and fiber nonlinearities effects at input signal power of 5 dBm and 3 spans of 100 km standard single mode fiber with a dispersion (D) value of 17 ps/nm.km.

Ratiobased vs. modelbased methods to correct for urinary creatinine concentrations.
Jain, Ram B
20160801
Creatininecorrected urinary analyte concentration is usually computed as the ratio of the observed level of analyte concentration divided by the observed level of the urinary creatinine concentration (UCR). This ratiobased method is flawed since it implicitly assumes that hydration is the only factor that affects urinary creatinine concentrations. On the contrary, it has been shown in the literature, that age, gender, race/ethnicity, and other factors also affect UCR. Consequently, an optimal method to correct for UCR should correct for hydration as well as other factors like age, gender, and race/ethnicity that affect UCR. Modelbased creatinine correction in which observed UCRs are used as an independent variable in regression models has been proposed. This study was conducted to evaluate the performance of ratiobased and modelbased creatinine correction methods when the effects of gender, age, and race/ethnicity are evaluated one factor at a time for selected urinary analytes and metabolites. It was observed that ratiobased method leads to statistically significant pairwise differences, for example, between males and females or between nonHispanic whites (NHW) and nonHispanic blacks (NHB), more often than the modelbased method. However, depending upon the analyte of interest, the reverse is also possible. The estimated ratios of geometric means (GM), for example, male to female or NHW to NHB, were also compared for the two methods. When estimated UCRs were higher for the group (for example, males) in the numerator of this ratio, these ratios were higher for the modelbased method, for example, male to female ratio of GMs. When estimated UCR were lower for the group (for example, NHW) in the numerator of this ratio, these ratios were higher for the ratiobased method, for example, NHW to NHB ratio of GMs. Modelbased method is the method of choice if all factors that affect UCR are to be accounted for.

Instability risk assessment of construction waste pile slope based on fuzzy entropy
NASA Astrophysics Data System (ADS)
Ma, Yong; Xing, Huige; Yang, Mao; Nie, Tingting
20180501
Considering the nature and characteristics of construction waste piles, this paper analyzed the factors affecting the stability of the slope of construction waste piles, and established the system of the assessment indexes for the slope failure risks of construction waste piles. Based on the basic principles and methods of fuzzy mathematics, the factor set and the remark set were established. The membership grade of continuous factor indexes is determined using the "ridge row distribution" function, while that for the discrete factor indexes was determined by the Delphi Method. For the weight of factors, the subjective weight was determined by the Analytic Hierarchy Process (AHP) and objective weight by the entropy weight method. And the distance function was introduced to determine the combination coefficient. This paper established a fuzzy comprehensive assessment model of slope failure risks of construction waste piles, and assessed pile slopes in the two dimensions of hazard and vulnerability. The root mean square of the hazard assessment result and vulnerability assessment result was the final assessment result. The paper then used a certain construction waste pile slope as the example for analysis, assessed the risks of the four stages of a landfill, verified the assessment model and analyzed the slope's failure risks and preventive measures against a slide.

NASA Astrophysics Data System (ADS)
Del Gaudio, Vincenzo; Wasowski, Janusz
20140501
Several studies have shown that the dynamic response of landslide prone slopes to seismic shaking can play an important role in failure triggering during earthquakes. It was also demonstrated that slope seismic response is often characterised by directional resonance phenomena. Directivity can be revealed by the analysis of ambient noise recordings according to a technique known as HVNR method based on the analysis of azimuthal variation of spectral ratios between the spectral amplitude of horizontal H and vertical V component of noise recording. Directional resonance is then revealed by the presence of a preferential polarisation of H/V ratio peaks, whose frequencies correspond to resonance frequencies and whose amplitudes depend on the impedance contrast between surface material and bedrock. H/V ratio amplitudes can potentially provide information also on amplification factors. However, the relation is not straightforward depending on the nature of the waves contributing to the ambient noise. Thus, it is desirable to distinguish different kinds of noise wave packets, possibly isolating the contribution of Rayleigh waves, which appear to better reflect site response properties. To identify Rayleigh wave packets in noise recording a new approach was tested, based on a technique of analysis of instantaneous polarisation. The results are promising for the investigation of site response directional properties, particularly in the case of complex site conditions, where resonance can be characterised by multiple anisotropic peaks. In our preliminary tests of noise recordings carried out at a site located on a slope affected by landslides, only a small fraction of data samples (in the order of 1 %) were identified as Rayleigh type waves: this was likely due the fact that the noise recording was dominated by an overlapping of signals with different kinds of polarisation. Thus, it was possible to recognise Rayleigh polarisation only when the energy of this kind of wave was

Laboratory and 3Ddistinct element analysis of failure mechanism of slope under external surcharge
NASA Astrophysics Data System (ADS)
Li, N.; Cheng, Y. M.
20140901
Landslide is a major disaster resulting in considerable loss of human lives and property damages in hilly terrain in Hong Kong, China and many other countries. The factor of safety and the critical slip surface for slope stabilization are the main considerations for slope stability analysis in the past, while the detailed postfailure conditions of the slopes have not been considered in sufficient details. There are however increasing interest on the consequences after the initiation of failure which includes the development and propagation of the failure surfaces, the amount of failed mass and runoff and the affected region. To assess the development of slope failure in more details and to consider the potential danger of slopes after failure has initiated, the slope stability problem under external surcharge is analyzed by the distinct element method (DEM) and laboratory model test in the present research. A more refined study about the development of failure, microcosmic failure mechanism and the postfailure mechanism of slope will be carried out. The numerical modeling method and the various findings from the present work can provide an alternate method of analysis of slope failure which can give additional information not available from the classical methods of analysis.
 «
 4
 5
 6
 7
 8
 »
 «
 5
 6
 7
 8
 9
 »

A calibration method for fringe reflection technique based on the analytical phaseslope description
NASA Astrophysics Data System (ADS)
Wu, Yuxiang; Yue, Huimin; Pan, Zhipeng; Liu, Yong
20180501
The fringe reflection technique (FRT) has been one of the most popular methods to measure the shape of specular surface these years. The existing system calibration methods of FRT usually contain two parts, which are camera calibration and geometric calibration. In geometric calibration, the liquid crystal display (LCD) screen position calibration is one of the most difficult steps among all the calibration procedures, and its accuracy is affected by the factors such as the imaging aberration, the plane mirror flatness, and LCD screen pixel size accuracy. In this paper, based on the deduction of FRT analytical phaseslope description, we present a novel calibration method with no requirement to calibrate the position of LCD screen. On the other hand, the system can be arbitrarily arranged, and the imaging system can either be telecentric or nontelecentric. In our experiment of measuring the 5000mm radius sphere mirror, the proposed calibration method achieves 2.5 times smaller measurement error than the geometric calibration method. In the wafer surface measuring experiment, the measurement result with the proposed calibration method is closer to the interferometer result than the geometric calibration method.

Predicting reading outcomes with progress monitoring slopes among middle grade students
Tolar, Tammy D.; Barth, Amy E.; Fletcher, Jack M.; Francis, David J.; Vaughn, Sharon
20130101
Effective implementation of responsetointervention (RTI) frameworks depends on efficient tools for monitoring progress. Evaluations of growth (i.e., slope) may be less efficient than evaluations of status at a single time point, especially if slopes do not add to predictions of outcomes over status. We examined progress monitoring slope validity for predicting reading outcomes among middle school students by evaluating latent growth models for different progress monitoring measureoutcome combinations. We used multigroup modeling to evaluate the effects of reading ability, reading intervention, and progress monitoring administration condition on slope validity. Slope validity was greatest when progress monitoring was aligned with the outcome (i.e., word reading fluency slope was used to predict fluency outcomes in contrast to comprehension outcomes), but effects varied across administration conditions (viz., repeated reading of familiar vs. novel passages). Unless the progress monitoring measure is highly aligned with outcome, slope may be an inefficient method for evaluating progress in an RTI context. PMID:24659899

Evaluation strategies for isotope ratio measurements of single particles by LAMCICPMS.
Kappel, S; Boulyga, S F; Dorta, L; Günther, D; Hattendorf, B; Koffler, D; Laaha, G; Leisch, F; Prohaska, T
20130301
Data evaluation is a crucial step when it comes to the determination of accurate and precise isotope ratios computed from transient signals measured by multicollectorinductively coupled plasma mass spectrometry (MCICPMS) coupled to, for example, laser ablation (LA). In the present study, the applicability of different data evaluation strategies (i.e. 'pointbypoint', 'integration' and 'linear regression slope' method) for the computation of (235)U/(238)U isotope ratios measured in single particles by LAMCICPMS was investigated. The analyzed uranium oxide particles (i.e. 907301B, CRM U010 and NUSIMEP7 test samples), having sizes down to the submicrometre range, are certified with respect to their (235)U/(238)U isotopic signature, which enabled evaluation of the applied strategies with respect to precision and accuracy. The different strategies were also compared with respect to their expanded uncertainties. Even though the 'pointbypoint' method proved to be superior, the other methods are advantageous, as they take weighted signal intensities into account. For the first time, the use of a 'finite mixture model' is presented for the determination of an unknown number of different U isotopic compositions of single particles present on the same planchet. The model uses an algorithm that determines the number of isotopic signatures by attributing individual data points to computed clusters. The (235)U/(238)U isotope ratios are then determined by means of the slopes of linear regressions estimated for each cluster. The model was successfully applied for the accurate determination of different (235)U/(238)U isotope ratios of particles deposited on the NUSIMEP7 test samples.

GaN Nanowire MOSFET with NearIdeal Subthreshold Slope.
Li, Wenjun; Brubaker, Matt D; Spann, Bryan T; Bertness, Kris A; Fay, Patrick
20180201
Wraparound gate GaN nanowire MOSFETs using Al 2 O 3 as gate oxide have been experimentally demonstrated. The fabricated devices exhibit a minimum subthreshold slope of 60 mV/dec, an average subthreshold slope of 68 mV/dec over three decades of drain current, draininduced barrier lowering of 27 mV/V, an oncurrent of 42 μA/μm (normalized by nanowire circumference), on/off ratio over 10 8 , an intrinsic transconductance of 27.8 μS/μm, for a switching efficiency figure of merit, Q=g m /SS of 0.41 μS/μmdec/mV. These performance metrics make GaN nanowire MOSFETs a promising candidate for emerging lowpower applications such as sensors and RF for the internet of things.

Gravityinduced stresses in finite slopes
Savage, W.Z.
19940101
An exact solution for gravityinduced stresses in finite elastic slopes is presented. This solution, which is applied for gravityinduced stresses in 15, 30, 45 and 90?? finite slopes, has application in pitslope design, compares favorably with published finite element results for this problem and satisfies the conditions that shear and normal stresses vanish on the ground surface. The solution predicts that horizontal stresses are compressive along the top of the slopes (zero in the case of the 90?? slope) and tensile away from the bottom of the slopes, effects which are caused by downward movement and nearsurface horizontal extension in front of the slope in response to gravity loading caused by the additional material associated with the finite slope. ?? 1994.

Method of Poisson's ratio imaging within a material part
NASA Technical Reports Server (NTRS)
Roth, Don J. (Inventor)
19960101
The present invention is directed to a method of displaying the Poisson's ratio image of a material part. In the present invention longitudinal data is produced using a longitudinal wave transducer and shear wave data is produced using a shear wave transducer. The respective data is then used to calculate the Poisson's ratio for the entire material part. The Poisson's ratio approximations are then used to displayed the image.

Research on discrete element simulation of anchor frame beam reinforcement in bedding shale slope
NASA Astrophysics Data System (ADS)
Zhang, Xiao yong; Xie, Xiao ting
20171101
The anchor frame beam is a new type of composite support method, which is a kind of slope protection structure considering the interaction between the anchors and the slope. Based on the reinforcement project of a bedding shale slope in Chengzhang highway, the reinforced effect of anchor frame beam is studied by discrete element method. Firstly, the mesoscopic parameters of the rock mass are obtained by calibration while that of anchor frame beam are obtained by calculation. Then the slope model with the reinforcement of anchor frame beam is established by particle flow software PFC2D. Afterwards, the statement of slope can be analyzed and the reinforcement effect of anchor frame beam can be predicted. Results show that: there is no instability in the slope after reinforcement, and the sliding of slope can be effectively prevented by anchor frame beam. The simulation results can provide reference for the design and construction of the project.

20141218
This image from NASA Mars Reconnaissance Orbiter shows frosted gullies on a southfacing slope within a crater. At this time of year only southfacing slopes retain the frost, while the northfacing slopes have melted.

Method for nanomachining high aspect ratio structures
Yun, Wenbing; Spence, John; Padmore, Howard A.; MacDowell, Alastair A.; Howells, Malcolm R.
20041109
A nanomachining method for producing highaspect ratio precise nanostructures. The method begins by irradiating a wafer with an energetic chargedparticle beam. Next, a layer of patterning material is deposited on one side of the wafer and a layer of etch stop or metal plating base is coated on the other side of the wafer. A desired pattern is generated in the patterning material on the top surface of the irradiated wafer using conventional electronbeam lithography techniques. Lastly, the wafer is placed in an appropriate chemical solution that produces a directional etch of the wafer only in the area from which the resist has been removed by the patterning process. The high mechanical strength of the wafer materials compared to the organic resists used in conventional lithography techniques with allows the transfer of the precise patterns into structures with aspect ratios much larger than those previously achievable.

Effects of grapevine root density and reinforcement on slopes prone to shallow slope instability
NASA Astrophysics Data System (ADS)
Meisina, Claudia; Bordoni, Massimiliano; Bischetti, Gianbattista; Vercesi, Alberto; Chiaradia, Enrico; Cislaghi, Alessio; Valentino, Roberto; Bittelli, Marco; Vergani, Chiara; Chersich, Silvia; Giuseppina Persichillo, Maria; Comolli, Roberto
20160401
Slope erosion and shallow slope instabilities are the major factors of soil losses in cultivated steep terrains. These phenomena also cause loss of organic matter and plants nutrients, together with the partial or total destruction of the structures, such as the row tillage pattern of the vineyards, which allow for the plants cultivation. Vegetation has long been used as an effective tool to decrease the susceptibility of a slope to erosion and to shallow landslides. In particular, the scientific research focused on the role played by the plant roots, because the belowground biomass has the major control on the potential development of soil erosion and of shallow failures. Instead, a comprehensive study that analyzes the effects of the roots of agricultural plants on both soil erosion and slope instability has not been carried out yet. This aspect should be fundamental where sloped terrains are cultivated with plants of great economical relevance, as grapevine. To contribute to fill this gap, in this study the features of root density in the soil profile have been analyzed in slopes cultivated with vineyards, located on a sample hilly area of Oltrepò Pavese (northern Italy). In this area, the viticulture is the most important branch of the local economy. Moreover, several events of rainfallinduced slope erosion and shallow landslides have occurred in this area in the last 6 years, causing several economical damages linked to the destruction of the vineyards and the loss of high productivity soils. Grapevine root distribution have been measured in different testsite slopes, representative of the main geological, geomorphological, pedological, landslides distribution, agricultural features, in order to identify particular patterns on root density that can influence the development of slope instabilities. Roots have been sampled in each testsite for characterizing their strength, in terms of the relation between root diameter and root force at rupture. Root

Herzog, Martha; Larsen, Curtis E.; McRae, Michele
20020101
Despite a long history of geomorphic studies, it is difficult to ascertain the time required for slopes to change from near vertical exposures to relatively stable slopes due to inadequate age control. Actively eroding coastal bluffs along the western shore of the Chesapeake Bay provide a key for understanding the centennialscale development of stable slopes from eroding bluff faces. The Calvert Cliffs are composed of sandy silts, silty sands, and clayey silts of Mioceneage. Active wave erosion at the bluff toes encourages rapid sloughing from bluff faces and maintains slope angles of 7080 degrees and relatively constant bluffretreat rates. Naturally stabilized slopes are preserved as a fossil bluff line inland from a prograding cuspate foreland at Cove Point. The foreland is migrating southward at a rate of ca. 1.5 m/yr. As it moves south, it progressively protects bluffs from wave action as new beaches are deposited at their toes. Wave erosion is reinitiated at the northern end of the complex as the landform passes. An incremental record of slope change is preserved along the fossil bluff line. 14C dating of swales between beach ridges shows the complex to span 1700 years of progressive migration history. We hypothesized that slopes would change from steep, eroding faces to lowangle slopes covered with vegetation and sought to document the rate of change. Our team measured slope angles at intervals along the fossil bluff line and dated profiles by interpolating 14C ages of adjacent beach ridges. There was no progressive decrease in slope with age. All slopes along the fossil bluff line were 3040 degrees with a mean of 35 degrees. Constancy in slope angle suggests that steep, actively eroding bluffs were quickly changed to stable slopes by landslides and slumping once they were protected. Given the accuracy of our age control, we conclude that the time required to attain a stable slope under natural processes is less than one century. This indicates that

Periodic equivalence ratio modulation method and apparatus for controlling combustion instability
Richards, George A.; Janus, Michael C.; Griffith, Richard A.
20000101
The periodic equivalence ratio modulation (PERM) method and apparatus significantly reduces and/or eliminates unstable conditions within a combustion chamber. The method involves modulating the equivalence ratio for the combustion device, such that the combustion device periodically operates outside of an identified unstable oscillation region. The equivalence ratio is modulated between preselected reference points, according to the shape of the oscillation region and operating parameters of the system. Preferably, the equivalence ratio is modulated from a first stable condition to a second stable condition, and, alternatively, the equivalence ratio is modulated from a stable condition to an unstable condition. The method is further applicable to multinozzle combustor designs, whereby individual nozzles are alternately modulated from stable to unstable conditions. Periodic equivalence ratio modulation (PERM) is accomplished by active control involving periodic, low frequency fuel modulation, whereby low frequency fuel pulses are injected into the main fuel delivery. Importantly, the fuel pulses are injected at a rate so as not to affect the desired timeaverage equivalence ratio for the combustion device.

Coeckelberghs, Ellen; Buys, Roselien; Goetschalckx, Kaatje; Cornelissen, Véronique A; Vanhees, Luc
20160201
Peak exercise capacity is an independent predictor for mortality in patients with coronary artery disease. However, sometimes cardiopulmonary exercise tests are stopped prematurely. Therefore, submaximal exercise measures such as the oxygen uptake efficiency slope have been introduced. The aim of this study was to assess the prognostic value of the oxygen uptake efficiency slope and other exercise parameters, in patients with coronary artery disease. Between 2000 and 2011, 1409 patients with coronary artery disease (age 60.7 ± 9.9 years; 1205 males) underwent cardiopulmonary exercise tests. A maximal effort was not reached in 161 (11.5%) patients. The oxygen uptake efficiency slope was calculated and information on mortality was obtained. Cox proportional hazards regression analyses were used to assess the relation of oxygen uptake efficiency slope and other gas exchange variables with allcause and cardiovascular mortality. Receiver operating characteristic curve analyses was performed to define optimal cutoff values. During an average followup of 7.45 ± 3.20 years (range 0.1613.95 years), 158 patients died, among which 68 patients for cardiovascular reasons. The oxygen uptake efficiency slope was related to allcause (hazard ratio: 0.568, p < 0.001) and cardiovascular (hazard ratio: 0.461, p < 0.001) mortality. When significant covariates were entered in the analysis, oxygen uptake efficiency slope remained related to mortality (p < 0.05). When other submaximal exercise parameters were added to the model, oxygen uptake efficiency slope and minute ventilation/carbon dioxide production slope also remained significantly related to mortality. The oxygen uptake efficiency slope is an independent predictor for allcause and cardiovascular mortality in patients with coronary artery disease, irrespective of a truly maximal effort during cardiopulmonary exercise tests. Furthermore, the oxygen uptake efficiency slope provides prognostic information

Balogh, A L; Petak, F; Fodor, G H; Tolnai, J; Csorba, Z; Babik, B
20160701
Capnography may provide useful noninvasive bedside information concerning heterogeneity in lung ventilation, ventilationperfusion mismatching and metabolic status. Although the capnogram may be recorded by mainstream and sidestream techniques, the capnogram indices furnished by these approaches have not previously been compared systematically. Simultaneous mainstream and sidestream time and volumetric capnography was performed in anaesthetized, mechanically ventilated patients undergoing elective heart surgery. Time capnography was used to assess the phase II (SII,T) and III slopes (SIII,T). The volumetric method was applied to estimate phase II (SII,V) and III slopes (SIII,V), together with the dead space values according to the Fowler (VDF), Bohr (VDB), and Enghoff (VDE) methods and the volume of CO2 eliminated per breath ([Formula: see text]). The partial pressure of endtidal CO2 ([Formula: see text]) was registered. Excellent correlation and good agreement were observed in SIII,T measured by the mainstream and sidestream techniques [ratio=1.05 (sem 0.16), R(2)=0.92, P<0.0001]. Although the sidestream technique significantly underestimated [Formula: see text] and overestimated SIII,V [1.32 (0.28), R(2)=0.93, P<0.0001], VDF, VDB, and VDE, the agreement between the mainstream and sidestream techniques in the difference between VDE and VDB, reflecting the intrapulmonary shunt, was excellent [0.97 (0.004), R(2)=0.92, P<0.0001]. The [Formula: see text] exhibited good correlation and mild differences between the mainstream and sidestream approaches [0.025 (0.005) kPa]. Sidestream capnography provides adequate quantitative bedside information about uneven alveolar emptying and ventilationperfusion mismatching, because it allows reliable assessments of the phase III slope, [Formula: see text] and intrapulmonary shunt. Reliable measurement of volumetric parameters (phase II slope, dead spaces, and eliminated CO2 volumes) requires the application of a mainstream

GIS/RSbased Rapid Reassessment for Slope Land Capability Classification
NASA Astrophysics Data System (ADS)
Chang, T. Y.; Chompuchan, C.
20141201
Farmland resources in Taiwan are limited because about 73% is mountainous and slope land. Moreover, the rapid urbanization and dense population resulted in the highly developed flat area. Therefore, the utilization of slope land for agriculture is more needed. In 1976, "Slope Land Conservation and Utilization Act" was promulgated to regulate the slope land utilization. Consequently, slope land capability was categorized into Class IIV according to 4 criteria, i.e., average land slope, effective soil depth, degree of soil erosion, and parent rock. The slope land capability Class IVI are suitable for cultivation and pasture. Whereas, Class V should be used for forestry purpose and Class VI should be the conservation land which requires intensive conservation practices. The field survey was conducted to categorize each land unit as the classification scheme. The landowners may not allow to overuse land capability limitation. In the last decade, typhoons and landslides frequently devastated in Taiwan. The rapid postdisaster reassessment of the slope land capability classification is necessary. However, the largescale disaster on slope land is the constraint of field investigation. This study focused on using satellite remote sensing and GIS as the rapid reevaluation method. Chenyulan watershed in Nantou County, Taiwan was selected to be a case study area. Gridbased slope derivation, topographic wetness index (TWI) and USLE soil loss calculation were used to classify slope land capability. The results showed that GISbased classification give an overall accuracy of 68.32%. In addition, the postdisaster areas of Typhoon Morakot in 2009, which interpreted by SPOT satellite imageries, were suggested to classify as the conservation lands. These tools perform better in the large coverage postdisaster update for slope land capability classification and reduce timeconsuming, manpower and material resources to the field investigation.

Mapping on Slope Seepage Problem using Electrical Resistivity Imaging (ERI)
NASA Astrophysics Data System (ADS)
Hazreek, Z. A. M.; Nizam, Z. M.; Aziman, M.; Dan, M. F. Md; Shaylinda, M. Z. N.; Faizal, T. B. M.; Aishah, M. A. N.; Ambak, K.; Rosli, S.; Rais, Y.; Ashraf, M. I. M.; Alel, M. N. A.
20180401
The stability of slope may influenced by several factors such as its geomaterial properties, geometry and environmental factors. Problematic slope due to seepage phenomenon will influenced the slope strength thus promoting to its failure. In the past, slope seepage mapping suffer from several limitation due to cost, time and data coverage. Conventional engineering tools to detect or mapped the seepage on slope experienced those problems involving large and high elevation of slope design. As a result, this study introduced geophysical tools for slope seepage mapping based on electrical resistivity method. Two spread lines of electrical resistivity imaging were performed on the slope crest using ABEM SAS 4000 equipment. Data acquisition configuration was based on long and short arrangement, schlumberger array and 2.5 m of equal electrode spacing interval. Raw data obtained from data acquisition was analyzed using RES2DINV software. Both of the resistivity results show that the slope studied consists of three different anomalies representing top soil (200 – 1000 Ωm), perched water (10 – 100 Ωm) and hard/dry layer (> 200 Ωm). It was found that seepage problem on slope studied was derived from perched water zones with electrical resistivity value of 10 – 100 Ωm. Perched water zone has been detected at 6 m depth from the ground level with varying thickness at 5 m and over. Resistivity results have shown some good similarity output with reference to borehole data, geological map and site observation thus verified the resistivity results interpretation. Hence, this study has shown that the electrical resistivity imaging was applicable in slope seepage mapping which consider efficient in term of cost, time, data coverage and sustainability.

Effect of Different Groundwater Levels on Seismic Dynamic Response and Failure Mode of Sandy Slope
Huang, Shuai; Lv, Yuejun; Peng, Yanju; Zhang, Lifang; Xiu, Liwei
20150101
Heavy seismic damage tends to occur in slopes when groundwater is present. The main objectives of this paper are to determine the dynamic response and failure mode of sandy slope subjected simultaneously to seismic forces and variable groundwater conditions. This paper applies the finite element method, which is a fast and efficient design tool in modern engineering analysis, to evaluate dynamic response of the slope subjected simultaneously to seismic forces and variable groundwater conditions. Shaking table test is conducted to analyze the failure mode and verify the accuracy of the finite element method results. The research results show that dynamic response values of the slope have different variation rules under near and far field earthquakes. And the damage location and pattern of the slope are different in varying groundwater conditions. The destruction starts at the top of the slope when the slope is in no groundwater, which shows that the slope appears obvious whipping effect under the earthquake. The destruction starts at the toe of the slope when the slope is in the high groundwater levels. Meanwhile, the top of the slope shows obvious seismic subsidence phenomenon after earthquake. Furthermore, the existence of the groundwater has a certain effect of damping. PMID:26560103

Experimental wave attenuation study over flexible plants on a submerged slope
NASA Astrophysics Data System (ADS)
Yin, Zegao; Yang, Xiaoyu; Xu, Yuanzhao; Ding, Meiling; Lu, Haixiang
20171201
Using plants is a kind of environmentallyfriendly coastal protection to attenuate wave energy. In this paper, a set of experiments were conducted to investigate the wave attenuation performance using flexible grasses on a submerged slope, and the wave attenuation coefficient for these experiments was calculated for different still water depths, slope and grass configurations. It was found that the slope plays a significant role in wave attenuation. The wave attenuation coefficient increases with increasing relative row number and relative density. For a small relative row number, the two configurations from the slope top to its toe and from the slope toe to its top performed equally to a large extent. For a medium relative row number, the configuration from the slope toe to its top performed more poorly than that from the slope top to its toe; however, it performed better than that from the slope top to its toe for a high relative row number. With a single row of grasses close to the slope top from the slope toe, the wave attenuation coefficient shows double peaks. With increasing grass rows or still water depth, the grass location corresponding to the maximum wave attenuation coefficient is close to the slope top. The dimensional analysis and the least square method were used to derive an empirical equation of the wave attenuation coefficient considering the effect of relative density, the slope, the relative row number and the relative location of the middle row, and the equation was validated to experimental data.

The relevance of the slope for concentrationeffect relations
DOE Office of Scientific and Technical Information (OSTI.GOV)
Schobben, H.P.M.; Smit, M.; Schobben, J.H.M.
19951231
Risk analysis is mostly based on a comparison of one value for the exposure to a chemical (PEC) and one value for the sensitivity of biota (NEC). This method enables the determination of an effect to be expected, but it is not possible to quantify the magnitude of that effect. Moreover, it is impossible to estimate the effect of a combination of chemicals. Therefore, it is necessary to use a mathematical function to describe the relation between a concentration and the subsequent effect. These relations are typically based on a log normal or log logistic distribution of the sensitivity ofmore» individuals of a species. This distribution is characterized by the median sensitivity (EC{sub 50}) and the variation between the sensitivity of individuals (being a measure for the slope of the relation). Presently the attention is focused on the median, while the slope might be even more important. Relevant exposure concentrations are typically in the range which are found in the left tail of the sensitivity distribution. In this study the slope was determined for 250 chemicalspecies combinations. The data were derived from original experiments and from literature. The slope is highly dependent on the exposure time; the shorter the exposure time the steeper the slope. If data for a standard exposure time [96 hours] are considered, the total variation in slope can partly be explained by the groups of organisms and chemicals. The slope for heavy metals tends to be less steep as compared to the slope of narcotic organic compounds. The slope for fish and molluscs is steeper than for crustaceans. The results of this study are presently applied in a number of risk analysis studies.«less

Efficient Meshfree Large Deformation Simulation of Rainfall Induced Soil Slope Failure
NASA Astrophysics Data System (ADS)
Wang, Dongdong; Li, Ling
20100501
An efficient Lagrangian Galerkin meshfree framework is presented for large deformation simulation of rainfallinduced soil slope failure. Detailed coupled soilrainfall seepage equations are given for the proposed formulation. This nonlinear meshfree formulation is featured by the Lagrangian stabilized conforming nodal integration method where the low cost nature of nodal integration approach is kept and at the same time the numerical stability is maintained. The initiation and evolution of progressive failure in the soil slope is modeled by the coupled constitutive equations of isotropic damage and DruckerPrager pressuredependent plasticity. The gradient smoothing in the stabilized conforming integration also serves as a nonlocal regularization of material instability and consequently the present method is capable of effectively capture the shear band failure. The efficacy of the present method is demonstrated by simulating the rainfallinduced failure of two typical soil slopes.
 «
 5
 6
 7
 8
 9
 »
 «
 6
 7
 8
 9
 10
 »

NASA Astrophysics Data System (ADS)
Cohen, D.; Giadrossich, F.; Schwarz, M.; Vergani, C.
20161201
Roots provide mechanical anchorage and reinforcement of soils on slopes. Roots also modify soil hydrological properties (soil moisture content, porewater pressure, preferential flow paths) via subsurface flow path associated with root architecture, root density, and rootsize distribution. Interactions of rootsoil mechanical and hydrological processes are an important control of shallow landslide initiation during rainfall events and slope stability. Knowledge of rootdistribution and root strength are key components to estimate slope stability in vegetated slopes and for the management of protection forest in steep mountainous area. We present data that show the importance of measuring root strength directly in the field and present methods for these measurements. These data indicate that the tensile force mobilized in roots depends on root elongation (a function of soil displacement), root size, and on whether roots break in tension of slip out of the soil. Measurements indicate that large lateral roots that cross tension cracks at the scarp are important for slope stability calculations owing to their large tensional resistance. These roots are often overlooked and when included, their strength is overestimated because extrapolated from measurements on small roots. We present planned field experiments that will measure directly the force held by roots of different sizes during the triggering of a shallow landslide by rainfall. These field data are then used in a model of root reinforcement based on fiberbundle concepts that span different spacial scales, from a single root to the stand scale, and different time scales, from timber harvest to root decay. This model computes the strength of root bundles in tension and in compression and their effect on soil strength. Upscaled to the stand the model yields the distribution of root reinforcement as a function of tree density, distance from tree, tree species and age with the objective of providing quantitative

NASA Astrophysics Data System (ADS)
Lin, J. Y.; Tsia, C. H.; Cheng, W. B.; Chin, S. J.; Lin, S. S.; Liang, C. W.
20151201
The Nakamura's method, which calculates the ratios between horizontal and vertical component spectra of seismic signals (H/V), is widely used in the inland area. However, few related estimations were performed for the offshore area and little knowledge for the marine sediments were obtained. From 2013 to 2015, three passive ocean bottom seismometer (OBS) experiments were conducted in gas hydraterich area offshore SW Taiwan in the aim of acquiring information related to the physical properties of seafloor sediments. The H/V of the seafloor sediments in the three areas were estimated by using the ambient noise and seismic signal recorded by OBSs. The resonance frequency of each site was estimated from the main peak of H/V distribution and a range between 5 and 10 Hz were obtained. Based on the empirical law, this resonance frequency range should correspond to a sediment thickness of approximately several to ten of meters. This estimation is consistent with the thickness of the sedimentary cover imaged by chirp sonar survey, suggesting that the site response of seafloor is dominantly controlled by the unconsolidated sedimentary layer on the top of the sea bed. Remarkably, the H/V ratios obtained in our study area are much larger than that calculated for the inland areas. The magnification can reach as high as 50 to more than 100. This observation infers that the sea water movement might emphasize the horizontal motion of the marine sediments, which is crucial for the slope stability assessment. Moreover, for most stations located in the active margin, no distinct peak is observed for the H/V pattern calculated during earthquakes. However, in the passive margin, the H/V peak calculated from ambient noise and earthquakes is mostly identical. This phenomenon may suggest that relatively unclear sedimentary boundary exist in the active margin environment. Estimating H/V spectral ratios of data recorded by the OBSs deployed in the southwest Taiwan offshore area offers a

Advance in prediction of soil slope instabilities
NASA Astrophysics Data System (ADS)
SigaránLoría, C.; Hack, R.; Nieuwenhuis, J. D.
20120401
Six generic soils (clays and sands) were systematically modeled with planestrain finite elements (FE) at varying heights and inclinations. A dataset was generated in order to develop predictive relations of soil slope instabilities, in terms of coseismic displacements (u), under strong motions with a linear multiple regression. For simplicity, the seismic loads are monochromatic artificial sinusoidal functions at four frequencies: 1, 2, 4, and 6 Hz, and the slope failure criterion used corresponds to near 10% Cartesian shear strains along a continuous region comparable to a slip surface. The generated dataset comprises variables from the slope geometry and site conditions: height, H, inclination, i, shear wave velocity from the upper 30 m, vs30, site period, Ts; as well as the input strong motion: yield acceleration, ay (equal to peak ground acceleration, PGA in this research), frequency, f; and in some cases moment magnitude, M, and Arias intensity, Ia, assumed from empirical correlations. Different datasets or scenarios were created: "Magnitudeindependent", "Magnitudedependent", and "Soildependent", and the data was statistically explored and analyzed with varying mathematical forms. Qualitative relations show that the permanent deformations are highly related to the soil class for the clay slopes, but not for the sand slopes. Furthermore, the slope height does not constrain the variability in the coseismic displacements. The input frequency decreases the variability of the coseismic displacements for the "Magnitudedependent" and "Soildependent" datasets. The empirical models were developed with two and three predictors. For the sands it was not possible because they could not satisfy the constrains from the statistical method. For the clays, the best models with the smallest errors coincided with the simple general form of multiple regression with three predictors (e.g. near 0.16 and 0.21 standard error, S.E. and 0.75 and 0.55 R2 for the "M

Impact of slope inclination on salt accumulation
NASA Astrophysics Data System (ADS)
Nachshon, Uri
20170401
Field measurements indicated on high variability in salt accumulation along natural and cultivated slopes, even for relatively hom*ogeneous soil conditions. It was hypothesised that slope inclination has an impact on the location of salt accumulation along the slope. A set of laboratory experiments and numerical models were used to explore the impact of slope inclination on salt accumulation. It was shown, experimentally, that for conditions of saline water source at the lower boundary of the slope  salt accumulates in low concentrations and hom*ogeneously along the entire slope, for moderate slopes. However, as inclination increases high salt concentrations were observed at the upper parts of the slope, leaving the lower parts of the slope relatively free of salt. The traditional flow and transport models did not predict the experimental observations as they indicated also for the moderate slopes on salt accumulation in the elevated parts of the slope, away of the saline water source. Consequently  a conceptual model was raised to explain the laboratory observations. It was suggested that the interactions between slope angle, evaporation rates, hydraulic conductivity of the medium and distribution of wetness along the slope affect the saline water flow path through the medium. This lead to preferential flow path close to the soilatmosphere interface for the steep slopes, which leads to constant wash of the salts from the evaporation front upward towards the slope upper parts, whereas for the moderate slopes, flow path is below the soilatmosphere interface, therefore salt that accumulates at the evaporation front is not being transported upward. Understanding of salt dynamics along slopes is important for agricultural and natural environments, as well as for civil engineering purposes. Better understanding of the salt transport processes along slopes will improve our ability to minimize and to cope with soil salinization processes. The laboratory experiments and

New method for estimating daily global solar radiation over sloped topography in China
NASA Astrophysics Data System (ADS)
Shi, Guoping; Qiu, Xinfa; Zeng, Yan
20180301
A new scheme for the estimation of daily global solar radiation over sloped topography in China is developed based on the Iqbal model C and MODIS cloud fraction. The effects of topography are determined using a digital elevation model. The scheme is tested using observations of solar radiation at 98 stations in China, and the results show that the mean absolute bias error is 1.51 MJ m2 d1 and the mean relative absolute bias error is 10.57%. Based on calculations using this scheme, the distribution of daily global solar radiation over slopes in China on four days in the middle of each season (15 January, 15 April, 15 July and 15 October 2003) at a spatial resolution of 1 km × 1 km are analyzed. To investigate the effects of topography on global solar radiation, the results determined in four mountains areas (Tianshan, Kunlun Mountains, Qinling, and Nanling) are discussed, and the typical characteristics of solar radiation over sloped surfaces revealed. In general, the new scheme can produce reasonable characteristics of solar radiation distribution at a high spatial resolution in mountain areas, which will be useful in analyses of mountain climate and planning for agricultural production.

The Contribution of Particle Swarm Optimization to ThreeDimensional Slope Stability Analysis
A Rashid, Ahmad Safuan; Ali, Nazri
20140101
Over the last few years, particle swarm optimization (PSO) has been extensively applied in various geotechnical engineering including slope stability analysis. However, this contribution was limited to twodimensional (2D) slope stability analysis. This paper applied PSO in threedimensional (3D) slope stability problem to determine the critical slip surface (CSS) of soil slopes. A detailed description of adopted PSO was presented to provide a good basis for more contribution of this technique to the field of 3D slope stability problems. A general rotating ellipsoid shape was introduced as the specific particle for 3D slope stability analysis. A detailed sensitivity analysis was designed and performed to find the optimum values of parameters of PSO. Example problems were used to evaluate the applicability of PSO in determining the CSS of 3D slopes. The first example presented a comparison between the results of PSO and PLAXI3D finite element software and the second example compared the ability of PSO to determine the CSS of 3D slopes with other optimization methods from the literature. The results demonstrated the efficiency and effectiveness of PSO in determining the CSS of 3D soil slopes. PMID:24991652

The contribution of particle swarm optimization to threedimensional slope stability analysis.
Kalatehjari, Roohollah; Rashid, Ahmad Safuan A; Ali, Nazri; Hajihassani, Mohsen
20140101
Over the last few years, particle swarm optimization (PSO) has been extensively applied in various geotechnical engineering including slope stability analysis. However, this contribution was limited to twodimensional (2D) slope stability analysis. This paper applied PSO in threedimensional (3D) slope stability problem to determine the critical slip surface (CSS) of soil slopes. A detailed description of adopted PSO was presented to provide a good basis for more contribution of this technique to the field of 3D slope stability problems. A general rotating ellipsoid shape was introduced as the specific particle for 3D slope stability analysis. A detailed sensitivity analysis was designed and performed to find the optimum values of parameters of PSO. Example problems were used to evaluate the applicability of PSO in determining the CSS of 3D slopes. The first example presented a comparison between the results of PSO and PLAXI3D finite element software and the second example compared the ability of PSO to determine the CSS of 3D slopes with other optimization methods from the literature. The results demonstrated the efficiency and effectiveness of PSO in determining the CSS of 3D soil slopes.

Field Methods for the Study of Slope and Fluvial Processes
Leopold, Luna Bergere; Leopold, Luna Bergere
19670101
In Belgium during the summer of 1966 the Commission on Slopes and the Commission on Applied Geomorphology of the International Geographical Union sponsored a joint symposium, with field excursions, and meetings of the two commissions. As a result of the conference and associated discussions, the participants expressed the view that it would be a contribution to scientific work relating to the subject area if the Commission on Applied Geomorphology could prepare a small manual describling the methods of field investigation being used by research scientists throughout the world in the study of various aspects of &lope development and fluvial processes. The Commission then assumed this responsibility and asked as many persons as were known to be. working on this subject to contribute whatever they wished in the way of descriptions of methods being employed.The purpose of the present manual is to show the variety of study methods now in use, to describe from the experience gained the limitations and advantages of different techniques, and to give pertinent detail which might be useful to other investigators. Some details that would be useful to know are not included in scientific publications, but in a manual on methods the details of how best t6 use a method has a place. Various persons have learned certain things which cannot be done, as well as some methods that are successful. It is our hope that comparison of methods tried will give the reader suggestions as to how a particular method might best be applied to his own circ*mstance.The manual does not purport to include methods used by all workers. In particular, it does not interfere with a more systematic treatment of the subject (1) or with various papers already published in the present journal. In fact we are sure that there are pertinent research methods that we do not know of and the Commission would be glad to receive additions and other ideas from those who find they have something to contribute. Also, the

NASA Technical Reports Server (NTRS)
Ortabasi, U.; Gray, E.; Ogallagher, J. J.
19840101
The testing of a hyperbolic trumpet nonimaging secondary concentrator with a parabolic dish having slope errors of about 10 mrad is reported. The trumpet, which has a concentration ratio of 2.1, increased the flux through a 141mm focal aperture by 72%, with an efficiency of 96%, thus demonstrating its potential for use in tandem with cheap dishes having relatively large slope errors.

Effects of slope smoothing in river channel modeling
NASA Astrophysics Data System (ADS)
Kim, Kyungmin; Liu, Frank; Hodges, Ben R.
20170401
In extending dynamic river modeling with the 1D SaintVenant equations from a single reach to a large watershed there are critical questions as to how much bathymetric knowledge is necessary and how it should be represented parsimoniously. The ideal model will include the detail necessary to provide realism, but not include extraneous detail that should not exert a control on a 1D (crosssection averaged) solution. In a SaintVenant model, the overall complexity of the river channel morphometry is typically abstracted into metrics for the channel slope, crosssectional area, hydraulic radius, and roughness. In stream segments where crosssection surveys are closely spaced, it is not uncommon to have sharp changes in slope or even negative values (where a positive slope is the downstream direction). However, solving river flow with the SaintVenant equations requires a degree of smoothness in the equation parameters or the equation set with the directly measured channel slopes may not be Lipschitz continuous. The results of nonsmoothness are typically extended computational time to converge solutions (or complete failure to converge) and/or numerical instabilities under transient conditions. We have investigated using cubic splines to smooth the bottom slope and ensure always positive reference slopes within a 1D model. This method has been implemented in the Simulation Program for River Networks (SPRNT) and is compared to the standard HECRAS river solver. It is shown that the reformulation of the reference slope is both in keeping with the underlying derivation of the SaintVenant equations and provides practical numerical stability without altering the realism of the simulation. This research was supported in part by the National Science Foundation under grant number CCF1331610.

ERIC Educational Resources Information Center
Wolbert, William
20170101
The query "When are we ever going to use this?" is easily answered when discussing the slope of a line. The pitch of a roof, the grade of a road, and stair stringers are three applications of slope that are used extensively. The concept of slope, which is introduced fairly early in the mathematics curriculum has handson applications…

NASA Astrophysics Data System (ADS)
Dutu, F.; Ion, G.; Jugaru Tiron, L.
20090401
The Black Sea is a large marginal sea surrounded by a system of Alpine orogenic chains, including the BalkanidesPontides, Caucasus, Crimea and North Dobrogea located to the south, northeast, north and northwest, respectively (Dinu et al., 2005). The northwestern part of the Black Sea is the main depocentre for sediment supply from Central Europe via the Danube River, but also from Eastern Europe through the Ukrainian rivers Dniepr, Dniestr and Southern Bug (Popescu et al., 2004). The shelfbreak is located at water depths of 120140 m southward of the Danube Canyon, and up to 170 m northward of the canyon possibly due to recent faulting which is very common in this area. The continental slope is dissected by numerous canyons, each of which is fed by several tributaries. The Danube Canyon (also known as Viteaz Canyon) is a large shelfindenting canyon located in the northwestern Black Sea and connected to the youngest channellevee system of the Danube Fan (Popescu et al., 2004). The acoustic methods are a useful way for investigate the shelf break and the continental slope giving us information about landslides on the continental slope, the topography of the investigated area, the sedimentary zones affected by instability and to quantify the geometry of the underwater landslides. The measurements made on the continental slope from northwestern part of the Black Sea gave us the possibility to make a digital terrain model. After processing the data the model offer information about the main access ways of the sediments through gravitational slide on the submarines canyons, with forming of turbidity currents, debris flows and also other transport/transformation phenomena of the sediments on the continental slope like submarine landslides and submarine collapse. References Dinu, C., Wong, H.K., Tambrea, D., Matenco, L., 2005. Stratigraphic and structural characteristics of the Romanian Black Sea shelf. Tectonophysics 410, 417435. Popescu, I., Lericolais, G., Panin

NASA Technical Reports Server (NTRS)
Moore, H. J.; Wu, S. C.
19730101
The effect of reading error on two hypothetical slope frequency distributions and two slope frequency distributions from actual lunar data in order to ensure that these errors do not cause excessive overestimates of algebraic standard deviations for the slope frequency distributions. The errors introduced are insignificant when the reading error is small and the slope length is large. A method for correcting the errors in slope frequency distributions is presented and applied to 11 distributions obtained from Apollo 15, 16, and 17 panoramic camera photographs and Apollo 16 metric camera photographs.

NASA Astrophysics Data System (ADS)
Li, N.; Cheng, Y. M.
20150101
Landslide is a major disaster resulting in considerable loss of human lives and property damages in hilly terrain in Hong Kong, China and many other countries. The factor of safety and the critical slip surface for slope stabilization are the main considerations for slope stability analysis in the past, while the detailed postfailure conditions of the slopes have not been considered in sufficient detail. There is however increasing interest in the consequences after the initiation of failure that includes the development and propagation of the failure surfaces, the amount of failed mass and runoff and the affected region. To assess the development of slope failure in more detail and to consider the potential danger of slopes after failure has initiated, the slope stability problem under external surcharge is analyzed by the distinct element method (DEM) and a laboratory model test in the present research. A more refined study about the development of failure, microcosmic failure mechanisms and the postfailure mechanisms of slopes will be carried out. The numerical modeling method and the various findings from the present work can provide an alternate method of analysis of slope failure, which can give additional information not available from the classical methods of analysis.

Solution algorithm of dwell time in slopebased figuring model
NASA Astrophysics Data System (ADS)
Li, Yong; Zhou, Lin
20171001
Surface slope profile is commonly used to evaluate Xray reflective optics, which is used in synchrotron radiation beam. Moreover, the measurement result of measuring instrument for Xray reflective optics is usually the surface slope profile rather than the surface height profile. To avoid the conversion error, the slopebased figuring model is introduced introduced by processing the Xray reflective optics based on surface heightbased model. However, the pulse iteration method, which can quickly obtain the dell time solution of the traditional heightbased figuring model, is not applied to the slopebased figuring model because property of the slope removal function have both positive and negative values and complex asymmetric structure. To overcome this problem, we established the optimal mathematical model for the dwell time solution, By introducing the upper and lower limits of the dwell time and the time gradient constraint. Then we used the constrained least squares algorithm to solve the dwell time in slopebased figuring model. To validate the proposed algorithm, simulations and experiments are conducted. A flat mirror with effective aperture of 80 mm is polished on the ion beam machine. After iterative polishing three times, the surface slope profile error of the workpiece is converged from RMS 5.65 μrad to RMS 1.12 μrad.

Derivation of martian surface slope characteristics from directional thermal infrared radiometry
NASA Astrophysics Data System (ADS)
Bandfield, Joshua L.; Edwards, Christopher S.
20080101
Directional thermal infrared measurements of the martian surface is one of a variety of methods that may be used to characterize surface roughness and slopes at scales smaller than can be obtained by orbital imagery. Thermal Emission Spectrometer (TES) emission phase function (EPF) observations show distinct apparent temperature variations with azimuth and emission angle that are consistent with the presence of warm, sunlit and cool, shaded slopes at typically ˜0.1 m scales. A surface model of a Gaussian distribution of azimuth independent slopes (described by θbar) is combined with a thermal model to predict surface temperature from each viewing angle and azimuth of the TES EPF observation. The models can be used to predict surface slopes using the difference in measured apparent temperature from 2 separate 6070° emission angle observations taken ˜180° in azimuth relative to each other. Most martian surfaces are consistent with low to moderate slope distributions. The slope distributions display distinct correlations with latitude, longitude, and albedo. Exceptionally smooth surfaces are located at lower latitudes in both the southern highlands as well as in high albedo dusty terrains. High slopes are associated with southern highlatitude patterned ground and north polar sand dunes. There is little apparent correlation between high resolution imagery and the derived θbar, with exceptions such as duneforms. This method can be used to characterize potential landing sites by assuming fractal scaling behavior to meter scales. More precisely targeted thermal infrared observations from other spacecraft instruments are capable of significantly reducing uncertainty as well as reducing measurement spot size from 10s of kilometers to subkilometer scales.

Absolute surface reconstruction by slope metrology and photogrammetry
NASA Astrophysics Data System (ADS)
Dong, Yue
Developing the manufacture of aspheric and freeform optical elements requires an advanced metrology method which is capable of inspecting these elements with arbitrary freeform surfaces. In this dissertation, a new surface measurement scheme is investigated for such a purpose, which is to measure the absolute surface shape of an object under test through its surface slope information obtained by photogrammetric measurement. A laser beam propagating toward the object reflects on its surface while the vectors of the incident and reflected beams are evaluated from the four spots they leave on the two parallel transparent windows in front of the object. The spots' spatial coordinates are determined by photogrammetry. With the knowledge of the incident and reflected beam vectors, the local slope information of the object surface is obtained through vector calculus and finally yields the absolute object surface profile by a reconstruction algorithm. An experimental setup is designed and the proposed measuring principle is experimentally demonstrated by measuring the absolute surface shape of a spherical mirror. The measurement uncertainty is analyzed, and efforts for improvement are made accordingly. In particular, structured windows are designed and fabricated to generate uniform scattering spots left by the transmitted laser beams. Calibration of the fringe reflection instrument, another typical surface slope measurement method, is also reported in the dissertation. Finally, a method for uncertainty analysis of a photogrammetry measurement system by optical simulation is investigated.

Slope histogram distributionbased parametrisation of Martian geomorphic features
NASA Astrophysics Data System (ADS)
Balint, Zita; Székely, Balázs; Kovács, Gábor
20140501
The application of geomorphometric methods on the large Martian digital topographic datasets paves the way to analyse the Martian areomorphic processes in more detail. One of the numerous methods is the analysis is to analyse local slope distributions. To this implementation a visualization program code was developed that allows to calculate the local slope histograms and to compare them based on Kolmogorov distance criterion. As input data we used the digital elevation models (DTMs) derived from HRSC highresolution stereo camera image from various Martian regions. The Kolmogorovcriterion based discrimination produces classes of slope histograms that displayed using coloration obtaining an image map. In this image map the distribution can be visualized by their different colours representing the various classes. Our goal is to create a local slope histogram based classification for large Martian areas in order to obtain information about general morphological characteristics of the region. This is a contribution of the TMIS.ascrea project, financed by the Austrian Research Promotion Agency (FFG). The present research is partly realized in the frames of TÁMOP 4.2.4.A/211120120001 high priority "National Excellence Program  Elaborating and Operating an Inland Student and Researcher Personal Support System convergence program" project's scholarship support, using Hungarian state and European Union funds and cofinances from the European Social Fund.

NASA Astrophysics Data System (ADS)
Hazelton, A.; Rogers, R.; Hart, R. E.
20131201
Recently, it has become apparent that typical methods for analyzing tropical cyclones (TCs), such as track and intensity, are insufficient for evaluating TC structural evolution and numerical model forecasts of that evolution. Many studies have analyzed different metrics related to TC innercore structure in an attempt to better understand the processes that drive changes in core structure. One important metric related to vertical TC structure is the slope of the eyewall. Hazelton and Hart (2013) discussed azimuthal mean eyewall slope based on radar reflectivity data, and its relationship with TC intensity and core structure. That study also noted significant azimuthal variation in slopes, but did not significantly explore reasons for this variation. Accordingly, in this study, we attempt to quantify the role of vertical wind shear in causing azimuthal variance of slope, using research quality Doppler radar composites from the NOAA Hurricane Research Division (HRD). We analyze the slope of the 20 dBZ surface as in Hazelton and Hart (2013), and also look at azimuthal variation in other measures of eyewall slope, such as the slope of the radius of maximum winds (RMW), which has been analyzed in an azimuthal mean sense by Stern and Nolan (2009), and an angular momentum surface. The shearrelative slopes are quantified by separating the radar data into four quadrants relative to the vertical shear vector: Downshear Left (DSL), Upshear Left (USL), Upshear Right (USR), and Downshear Right (DSR). This follows the method employed in shearrelative analyses of other aspects of TC core structure, such as Rogers et al. (2013) and Reasor et al. (2013). The data suitable for use in this study consist of 36 flights into 15 different TCs (14 Atlantic, 1 Eastern Pacific) between 1997 and 2010. Preliminary results show apparent shearinduced asymmetries in eyewall slope. The slope of the RMW shows an asymmetry due to the tilt of the vortex approximately along the shear vector, with

Application of FBG Sensing Technology in Stability Analysis of GeogridReinforced Slope.
Sun, Yijie; Xu, Hongzhong; Gu, Peng; Hu, Wenjie
20170315
By installing FBG sensors on the geogrids, smart geogrids can both reinforce and monitor the stability for geogridreinforced slopes. In this paper, a geogridreinforced sand slope model test is conducted in the laboratory and fiber Bragg grating (FBG) sensing technology is used to measure the strain distribution of the geogrid. Based on the model test, the performance of the reinforced soil slope is simulated by finite element software MidasGTS, and the stability of the reinforced soil slope is analyzed by strength reduction method. The relationship between the geogrid strain and the factor of safety is set up. The results indicate that the measured strain and calculated results agree very well. The geogrid strain measured by FBG sensor can be applied to evaluate the stability of geogridreinforced sand slopes.
 «
 6
 7
 8
 9
 10
 »
 «
 7
 8
 9
 10
 11
 »

Application of FBG Sensing Technology in Stability Analysis of GeogridReinforced Slope
Sun, Yijie; Xu, Hongzhong; Gu, Peng; Hu, Wenjie
20170101
By installing FBG sensors on the geogrids, smart geogrids can both reinforce and monitor the stability for geogridreinforced slopes. In this paper, a geogridreinforced sand slope model test is conducted in the laboratory and fiber Bragg grating (FBG) sensing technology is used to measure the strain distribution of the geogrid. Based on the model test, the performance of the reinforced soil slope is simulated by finite element software MidasGTS, and the stability of the reinforced soil slope is analyzed by strength reduction method. The relationship between the geogrid strain and the factor of safety is set up. The results indicate that the measured strain and calculated results agree very well. The geogrid strain measured by FBG sensor can be applied to evaluate the stability of geogridreinforced sand slopes. PMID:28294995

Correction of broadband albedo measurements affected by unknown slope and sensor tilts
NASA Astrophysics Data System (ADS)
Weiser, Ursula; Olefs, Marc; Schöner, Wolfgang; Weyss, Gernot; Hynek, Bernhard
20170201
Geometric effects induced by the underlying terrain slope or by tilt errors of radiation sensors lead to an erroneous measurement of snow or ice albedo. Consequently, diurnal albedo variations are observed. A general method to correct tilt errors of albedo measurements in cases where tilts of both the sensors and the slopes are not accurately measured or known is presented. Atmospheric parameters for this correction method can either be taken from a nearby wellmaintained and horizontally levelled measurement of global radiation or alternatively from a solar radiation model. In a next step the model is fitted to the measured data to determine tilts and directions of the sensors and the underlying terrain slope. This then allows to correct the measured albedo, the radiative balance and the energy balance. Depending on the direction of the slope and the sensors a comparison between measured and corrected albedo values reveals obvious overor underestimations of albedo.

Estimating Slopes In Images Of Terrain By Use Of BRDF
NASA Technical Reports Server (NTRS)
Scholl, Marija S.
19950101
Proposed method of estimating slopes of terrain features based on use of bidirectional reflectivity distribution function (BRDF) in analyzing aerial photographs, satellite video images, or other images produced by remote sensors. Estimated slopes integrated along horizontal coordinates to obtain estimated heights; generating threedimensional terrain maps. Method does not require coregistration of terrain features in pairs of images acquired from slightly different perspectives nor requires Sun or other source of illumination to be low in sky over terrain of interest. On contrary, best when Sun is high. Works at almost all combinations of illumination and viewing angles.

GISbased seismic shaking slope vulnerability map of Sicily (Central Mediterranean)
NASA Astrophysics Data System (ADS)
Nigro, Fabrizio; Arisco, Giuseppe; Perricone, Marcella; Renda, Pietro; Favara, Rocco
20100501
Earthquakes often represent very dangerouses natural events in terms of human life and economic losses and their damage effects are amplified by the synchronous occurrence of seismicallyinduced groundshaking failures in wide regions around the seismogenic source. In fact, the shaking associated with big earthquakes triggers extensive landsliding, sometimes at distances of more than 100 km from the epicenter. The active tectonics and the geomorphic/morphodinamic pattern of the regions affected by earthquakes contribute to the slopes instability tendency. In fact, earthquakeinduced grounmotion loading determines inertial forces activation within slopes that, combined with the intrinsic preexisting static forces, reduces the slope stability towards its failure. Basically, under zeroshear stress reversals conditions, a catastrophic failure will take place if the earthquakeinduced shear displacement exceeds the critical level of undrained shear strength to a value equal to the gravitational shear stress. However, seismic stability analyses carried out for various infinite slopes by using the existing Newmarklike methods reveal that estimated permanent displacements smaller than the critical value should also be regarded as dangerous for the postearthquake slope safety, in terms of human activities use. Earthquakeinduced (often highspeed) landslides are among the most destructive phenomena related to slopes failure during earthquakes. In fact, damage from earthquakeinduced landslides (and other groundfailures), sometimes exceeds the buildings/infrastructures damage directly related to groundshaking for fault breaking. For this matter, several hearthquakesrelated slope failures methods have been developed, for the evaluation of the combined hazard types represented by seismically groundmotion landslides. The methodologies of analysis of the engineering seismic risk related to the slopes instability processes is often achieved through the evaluation of the

Slopescale dynamic states of rockfalls
NASA Astrophysics Data System (ADS)
Agliardi, F.; Crosta, G. B.
20090401
Rockfalls are common earth surface phenomena characterised by complex dynamics at the slope scale, depending on local block kinematics and slope geometry. We investigated the nature of this slopescale dynamics by parametric 3D numerical modelling of rockfalls over synthetic slopes with different inclination, roughness and spatial resolution. Simulations were performed through an original code specifically designed for rockfall modeling, incorporating kinematic and hybrid algorithms with different damping functions available to model local energy loss by impact and pure rolling. Modelling results in terms of average velocity profiles suggest that three dynamic regimes (i.e. decelerating, steadystate and accelerating), previously recognized in the literature through laboratory experiments on granular flows, can set up at the slope scale depending on slope average inclination and roughness. Sharp changes in rock fall kinematics, including motion type and lateral dispersion of trajectories, are associated to the transition among different regimes. Associated threshold conditions, portrayed in "phase diagrams" as sloperoughness critical lines, were analysed depending on block size, impact/rebound angles, velocity and energy, and model spatial resolution. Motion in regime B (i.e. steady state) is governed by a slopescale "viscous friction" with average velocity linearly related to the sine of slope inclination. This suggest an analogy between rockfall motion in regime B and newtonian flow, whereas in regime C (i.e. accelerating) an analogy with a dilatant flow was observed. Thus, although local behavior of single falling blocks is well described by rigid body dynamics, the slope scale dynamics of rockfalls seem to statistically approach that of granular media. Possible outcomes of these findings include a discussion of the transition from rockfall to granular flow, the evaluation of the reliability of predictive models, and the implementation of criteria for a

NASA Astrophysics Data System (ADS)
Prabowo, U. N.; Amalia, A. F.; Wiranata, F. E.
20180301
This paper investigated soil slopelocal site effect of earthquake inducing landslide by using microtremor Horizontal to Vertical Spectral Ratio (HVSR) method. Microtremor measurements of 15 sites which were recorded for 45 minutes at each site were carried out in Ngargosari village, Samigaluh, Kulon ProgoIndonesia. Microtremor analysis using HVSR method was performed using Geopsy software. HVSR method resulted in predominant frequency values that ranges between 2,77 to 13,82 Hz and amplification factors varied from 0,46 to 5,70. The predominant frequency is associated with the depth of bedrock and the amplification factor reflects the geological condition of soil (sedimentary layer). The soil vulnerability index (Kg) varied from 0,08 to 5,77 and the higher value (Kg>3,4) in the south of the research area was identified as the weak zone of earthquake inducing landslide.

The RATIO method for timeresolved Laue crystallography
Coppens, Philip; Pitak, Mateusz; Gembicky, Milan; Messerschmidt, Marc; Scheins, Stephan; Benedict, Jason; Adachi, Shinichi; Sato, Tokushi; Nozawa, Shunsuke; Ichiyanagi, Kohei; Chollet, Matthieu; Koshihara, Shinya
20090101
A RATIO method for analysis of intensity changes in timeresolved pump–probe Laue diffraction experiments is described. The method eliminates the need for scaling the data with a wavelength curve representing the spectral distribution of the source and removes the effect of possible anisotropic absorption. It does not require relative scaling of series of frames and removes errors due to all but very short term fluctuations in the synchrotron beam. PMID:19240334

Yan, Yifei; Zhang, Lisong; Yan, Xiangzhen
20160101
In this paper, a singleslope tunnel pipeline was analysed considering the effects of vertical earth pressure, horizontal soil pressure, inner pressure, thermal expansion force and pipeline—soil friction. The concept of stagnation point for the pipeline was proposed. Considering the deformation compatibility condition of the pipeline elbow, the push force of anchor blocks of a singleslope tunnel pipeline was derived based on an energy method. Then, the theoretical formula for this force is thus generated. Using the analytical equation, the push force of the anchor block of an X80 largediameter pipeline from the West—East Gas Transmission Project was determined. Meanwhile, to verify the results of the analytical method, and the finite element method, four categories of finite element codes were introduced to calculate the push force, including CAESARII, ANSYS, AutoPIPE and ALGOR. The results show that the analytical results agree well with the numerical results, and the maximum relative error is only 4.1%. Therefore, the results obtained with the analytical method can satisfy engineering requirements. PMID:26963097

Stewart, Anne M.; Callegary, James B.; Smith, Christopher F.; Gupta, Hoshin V.; Leenhouts, James M.; Fritzinger, Robert A.
20120101
The continuous slopearea (CSA) method is an innovative gaging method for indirect computation of completeevent discharge hydrographs that can be applied when direct measurement methods are unsafe, impractical, or impossible to apply. This paper reports on use of the method to produce eventspecific discharge hydrographs in a network of sandbedded ephemeral stream channels in southeast Arizona, USA, for water year 2008. The method provided satisfactory discharge estimates for flows that span channel banks, and for moderate to large flows, with about 10–16% uncertainty, respectively for total flow volume and peak flow, as compared to results obtained with an alternate method. Our results also suggest that the CSA method may be useful for estimating runoff of small flows, and during recessions, but with increased uncertainty.

Stability of submarine slopes in the northern South China Sea: a numerical approach
NASA Astrophysics Data System (ADS)
Zhang, Liang; Luan, Xiwu
20130101
Submarine landslides occur frequently on most continental margins. They are effective mechanisms of sediment transfer but also a geological hazard to seafloor installations. In this paper, submarine slope stability is evaluated using a 2D limit equilibrium method. Considerations of slope, sediment, and triggering force on the factor of safety (FOS) were calculated in drained and undrained ( Φ=0) cases. Results show that submarine slopes are stable when the slope is <16° under static conditions and without a weak interlayer. With a weak interlayer, slopes are stable at <18° in the drained case and at <9° in the undrained case. Earthquake loading can drastically reduce the shear strength of sediment with increased pore water pressure. The slope became unstable at >13° with earthquake peak ground acceleration (PGA) of 0.5 g; whereas with a weak layer, a PGA of 0.2 g could trigger instability at slopes >10°, and >3° for PGA of 0.5 g. The northern slope of the South China Sea is geomorphologically stable under static conditions. However, because of the possibility of high PGA at the eastern margin of the South China Sea, submarine slides are likely on the Taiwan Bank slope and eastern part of the Dongsha slope. Therefore, submarine slides recognized in seismic profiles on the Taiwan Bank slope would be triggered by an earthquake, the most important factor for triggering submarine slides on the northern slope of the South China Sea. Considering the distribution of PGA, we consider the northern slope of the South China Sea to be stable, excluding the Taiwan Bank slope, which is tectonically active.

Submicroradian Surface Slope Metrology with the ALS Developmental Long Trace Profiler
DOE Office of Scientific and Technical Information (OSTI.GOV)
Yashchuk, Valeriy V.; Barber, Samuel; Domning, Edward E.
20090615
Development of Xray optics for 3rd and 4th generation Xray light sources with a level of surface slope precision of 0.10.2 {micro}rad requires the development of adequate fabrication technologies and dedicated metrology instrumentation and methods. Currently, the best performance of surface slope measurement has been achieved with the NOM (Nanometer Optical Component Measuring Machine) slope profiler at BESSY (Germany) [1] and the ESAD (Extended Shear Angle Difference) profiler at the PTB (Germany) [2]. Both instruments are based on electronic autocollimators (AC) precisely calibrated for the specific application [3] with small apertures of 2.55 mm in diameter. In the present work,more» we describe the design, initial alignment and calibration procedures, the instrumental control and data acquisition system, as well as the measurement performance of the Developmental Long Trace Profiler (DLTP) slope measuring instrument recently brought into operation at the Advanced Light Source (ALS) Optical Metrology Laboratory (OML). Similar to the NOM and ESAD, the DLTP is based on a precisely calibrated autocollimator. However, this is a reasonably low budget instrument used at the ALS OML for the development and testing of new measuring techniques and methods. Some of the developed methods have been implemented into the ALS LTPII (slope measuring long trace profiler [4]) which was recently upgraded and has demonstrated a capability for 0.25 {micro}rad surface metrology [5]. Performance of the DLTP was verified via a number of measurements with high quality reference mirrors. A comparison with the corresponding results obtained with the world's best slope measuring instrument, the BESSY NOM, proves the accuracy of the DLTP measurements on the level of 0.10.2 {micro}rad depending on the curvature of a surface under test. The directions of future work to develop a surface slope measuring profiler with nanoradian performance are also discussed.«less

Significance of parametric spectral ratio methods in detection and recognition of whispered speech
NASA Astrophysics Data System (ADS)
Mathur, Arpit; Reddy, Shankar M.; Hegde, Rajesh M.
20121201
In this article the significance of a new parametric spectral ratio method that can be used to detect whispered speech segments within normally phonated speech is described. Adaptation methods based on the maximum likelihood linear regression (MLLR) are then used to realize a mismatched traintest style speech recognition system. This proposed parametric spectral ratio method computes a ratio spectrum of the linear prediction (LP) and the minimum variance distortionless response (MVDR) methods. The smoothed ratio spectrum is then used to detect whispered segments of speech within neutral speech segments effectively. The proposed LPMVDR ratio method exhibits robustness at different SNRs as indicated by the whisper diarization experiments conducted on the CHAINS and the cell phone whispered speech corpus. The proposed method also performs reasonably better than the conventional methods for whisper detection. In order to integrate the proposed whisper detection method into a conventional speech recognition engine with minimal changes, adaptation methods based on the MLLR are used herein. The hidden Markov models corresponding to neutral mode speech are adapted to the whispered mode speech data in the whispered regions as detected by the proposed ratio method. The performance of this method is first evaluated on whispered speech data from the CHAINS corpus. The second set of experiments are conducted on the cell phone corpus of whispered speech. This corpus is collected using a set up that is used commercially for handling public transactions. The proposed whisper speech recognition system exhibits reasonably better performance when compared to several conventional methods. The results shown indicate the possibility of a whispered speech recognition system for cell phone based transactions.

NASA Astrophysics Data System (ADS)
Afzalian, Aryan; Colinge, JeanPierre; Flandre, Denis
20110501
A new concept of nanoscale MOSFET, the Gate Modulated Resonant Tunneling Transistor (RTFET), is presented and modeled using 3D NonEquilibrium Green's Function simulations enlightening the main physical mechanisms. Owing to the additional tunnel barriers and the related longitudinal confinement present in the device, the density of state is reduced in its offstate, while remaining comparable in its onstate, to that of a MOS transistor without barriers. The RTFET thus features both a lower RTlimited offcurrent and a faster increase of the current with V G, i.e. an improved slope characteristic, and hence an improved Ion/ Ioff ratio. Such improvement of the slope can happen in subthreshold regime, and therefore lead to subthreshold slope below the kT/q limit. In addition, faster increase of current and improved slope occur above threshold and lead to high thermionic oncurrent and significant Ion/ Ioff ratio improvement, even with threshold voltage below 0.2 V and supply voltage V dd of a few hundreds of mV as critically needed for future technology nodes. Finally RTFETs are intrinsically immune to sourcedrain tunneling and are therefore promising candidate for extending the roadmap below 10 nm.

Regional variability of slope stability: Application to the Eel margin, California
Lee, H.; Locat, J.; Dartnell, P.; Israel, K.; Florence, Wong
19990101
Relative values of downslope driving forces and sediment resisting forces determine the locations of submarine slope failures. Both of these vary regionally, and their impact can be addressed when the data are organized in a Geographic Information System (GIS). The study area on the continental margin near the Eel River provides an excellent opportunity to apply GIS spatial analysis techniques for evaluation of slope stability. In this area, swath bathymetric mapping shows seafloor morphology and distribution of slope steepness in fine detail, and sediment analysis of over 70 box cores delineates the variability of sediment density near the seafloor surface. Based on the results of ten geotechnical studies of submarine study areas, we developed an algorithm that relates surface sediment density to the shear strength appropriate to the type of cyclic loading produced by an earthquake. Strength and stress normalization procedures provide results that are conceptually independent of subbottom depth. Results at depth are rigorously applicable if sediment lithology does not vary significantly and consolidation state can be estimated. Otherwise, the method applies only to shallowseated slope failure. Regional density, slope, and level of anticipated seismic shaking information were combined in a GIS framework to yield a map that illustrates the relative stability of slopes in the face of seismically induced failure. When a measure of predicted relative slope stability is draped on an oblique view of swath bathymetry, a variation in this slope stability is observed on an otherwise smooth slope along the midslope region north of a plunging anticline. The section of slope containing diffuse, pockmarked gullies has a lower measure of stability than a separate section containing gullies that have sharper boundaries and somewhat steeper sides. Such an association suggests that our slopestability analysis relates to the stability of the gully sides. The remainder of the

Application of soil nails to the stability of mine waste slopes
DOE Office of Scientific and Technical Information (OSTI.GOV)
Tant, C.R.; Drumm, E.C.; Mauldon, M.
19961231
The traditional soil nailed structure incorporates grouted or driven nails, and a wire mesh reinforced shotcrete facing to increase the stability of a slope or wall. This paper describes the construction and monitoring of a fullscale demonstration of nailing to stabilize coal mine spoil. The purpose of the investigation is to evaluate the performance of nailed slopes in mine spoil using methods proven for the stabilization of soil walls and slopes. The site in eastern Tennessee is a 12 meter high slope of dumped fill, composed of weathered shale chips, sandstone, and coal. The slope was formed by {open_quotes}preregulatory{close_quotes} contourmore» surface mining operations and served as a work bench during mining. The material varies in size from silt to boulders, and has a small amount of cohesion. Portions of the mine spoil slope have experienced slope instability and erosion which have hampered subsequent reclamation activities. Three different nail spacings and three different nail lengths were used in the design. The 12 meter high structure is instrumented to permit measurement of nail strain, and vertical inclinometer readings and survey measurements will be used for the detection of ground movement. The results of this study will aid in the development of design recommendations and construction guidelines for the application of soil nailing to stabilize mine spoil.«less

Tiltmeter Indicates Sense of Slope
NASA Technical Reports Server (NTRS)
Lonborg, J. O.
19850101
Tiltmeter indicates sense and magnitude of slope used in locations where incline not visible to operator. Use of direct rather than alternating current greatly simplifies design of instrument capable of indicating sense of slope.

Validation of measurements of ventilationtoperfusion ratio inequality in the lung from expired gas
NASA Technical Reports Server (NTRS)
Prisk, G. Kim; Guy, Harold J B.; West, John B.; Reed, James W.
20030101
The analysis of the gas in a single expirate has long been used to estimate the degree of ventilationperfusion (Va/Q) inequality in the lung. To further validate this estimate, we examined three measures of Va/Q inhom*ogeneity calculated from a single full exhalation in nine anesthetized mongrel dogs under control conditions and after exposure to aerosolized methacholine. These measurements were then compared with arterial blood gases and with measurements of Va/Q inhom*ogeneity obtained using the multiple inert gas elimination technique. The slope of the instantaneous respiratory exchange ratio (R slope) vs. expired volume was poorly correlated with independent measures, probably because of the curvilinear nature of the relationship due to continuing gas exchange. When R was converted to the intrabreath Va/Q (iV/Q), the best index was the slope of iV/Q vs. volume over phase III (iV/Q slope). This was strongly correlated with independent measures, especially those relating to inhom*ogeneity of perfusion. The correlations for iV/Q slope and R slope considerably improved when only the first half of phase III was considered. We conclude that a useful noninvasive measurement of Va/Q inhom*ogeneity can be derived from the intrabreath respiratory exchange ratio.

Yin, Mojuan; Huang, Shenghong; Lu, Baole; Chen, Haowei; Ren, Zhaoyu; Bai, Jintao
20130920
A highslopeefficiency singlefrequency (SF) ytterbiumdoped fiber laser, based on a Sagnac loop mirror filter (LMF), was demonstrated. It combined a simple linear cavity with a Sagnac LMF that acted as a narrowbandwidth filter to select the longitudinal modes. And we introduced a polarization controller to restrain the spatial hole burning effect in the linear cavity. The system could operate at a stable SF oscillating at 1064nm with the obtained maximum output power of 32mW. The slope efficiency was found to be primarily dependent on the reflectivity of the fiber Bragg grating. The slope efficiency of multilongitudinal modes was higher than 45%, and the highest slope efficiency of the single longitudinal mode we achieved was 33.8%. The power stability and spectrum stability were <2% and <0.1%, respectively, and the signaltonoise ratio measured was around 60dB.

NASA Astrophysics Data System (ADS)
Alawadi, Wisam; AlRekabi, Wisam S.; AlAboodi, Ali H.
20180301
The Shiono and Knight Method (SKM) is widely used to predict the lateral distribution of depthaveraged velocity and boundary shear stress for flows in compound channels. Three calibrating coefficients need to be estimated for applying the SKM, namely eddy viscosity coefficient ( λ), friction factor ( f) and secondary flow coefficient ( k). There are several tested methods which can satisfactorily be used to estimate λ, f. However, the calibration of secondary flow coefficients k to account for secondary flow effects correctly is still problematic. In this paper, the calibration of secondary flow coefficients is established by employing two approaches to estimate correct values of k for simulating asymmetric compound channel with different side slopes of the internal wall. The first approach is based on Abril and Knight (2004) who suggest fixed values for main channel and floodplain regions. In the second approach, the equations developed by Devi and Khatua (2017) that relate the variation of the secondary flow coefficients with the relative depth ( β) and width ratio ( α) are used. The results indicate that the calibration method developed by Devi and Khatua (2017) is a better choice for calibrating the secondary flow coefficients than using the first approach which assumes a fixed value of k for different flow depths. The results also indicate that the boundary condition based on the shear force continuity can successfully be used for simulating rectangular compound channels, while the continuity of depthaveraged velocity and its gradient is accepted boundary condition in simulations of trapezoidal compound channels. However, the SKM performance for predicting the boundary shear stress over the shear layer region may not be improved by only imposing the suitable calibrated values of secondary flow coefficients. This is because difficulties of modelling the complex interaction that develops between the flows in the main channel and on the floodplain in this

Change Analysis of Laser Scans of Laboratory Rock Slopes Subject to Wave Attack Testing
NASA Astrophysics Data System (ADS)
Shen, Y.; Lindenbergh, R.; Hofland, B.; Kramer, R.
20170901
For better understanding how coastal structures with gentle slopes behave during high energy events, a wave attack experiment representing a storm of 3000 waves was performed in a flume facility. Two setups with different steepness of slope were compared under the same conditions. In order to quantify changes in the rock slopes after the wave attack, a terrestrial laser scanner was used to obtain 3D coordinates of the rock surface before and after each experiment. Next, through a series of processing steps, the point clouds were converted to a suitable 2D raster for change analysis. This allowed to estimate detailed and quantitative change information. The results indicate that the area around the artificial coast line, defined as the intersection between sloped surface and wave surface, is most strongly affected by wave attacks. As the distances from the sloped surface to the waves are shorter, changes for the mildly sloped surface, slope 1 (1 : 10), are distributed over a larger area compared to the changes for the more steeply sloped surface, slope 2 (1 : 5). The results of this experiment show that terrestrial laser scanning is an effective and feasible method for change analysis of rock slopes in a laboratory setting. Most striking results from a process point of view is that the transport direction of the rocks change between the two different slopes: from seaward transport for the steeper slope to landward transport for the milder slope.
 «
 7
 8
 9
 10
 11
 »
 «
 8
 9
 10
 11
 12
 »

Origin of the belllike dependence of the DPOAE amplitude on primary frequency ratio
NASA Astrophysics Data System (ADS)
Lukashkin, Andrei N.; Russell, Ian J.
20011201
For low and medium sound pressure levels (SPLs), the amplitude of the distortion product otoacoustic emission (DPOAE) recorded from guinea pigs at the 2f1f2 frequency is maximal when f2/f1~1.23 and decreases for lower and higher f2/f1 ratios. The highratio slope of the DPOAE dependence on the ratio of the primary frequencies might be anticipated since the f1 amplitude at the f2 place is expected to decrease for higher f2/f1 ratios. The lowratio slope of the dependence at low and medium SPLs of the primaries is actually one slope of a notch. The DPOAE amplitude recovers from the notch when the f2/f1 ratio is further reduced. In twodimensional space formed by the f2/f1 ratio, and the levels of the primaries, the notch is continuous and has a leveldependent phase transition. The notch is identical to that seen in DPOAE growth functions. Similar notches and phase transitions were observed for highorder and highfrequency DPOAEs. Theoretical analysis reveals that a single saturating nonlinearity is capable of generating similar amplitude notch and phase transition when the f2/f1 ratio is decreased because of the increase in f1 amplitude at the DPOAE generation place (f2 place). The difference between the DPOAE recorded from guinea pigs and humans is discussed in terms of different position of the operating point of the DPOAE generating nonlinearity.

Combustion engine variable compression ratio apparatus and method
Lawrence,; Keith, E [Peoria, IL; Strawbridge, Bryan E [Dunlap, IL; Dutart, Charles H [Washington, IL
20060606
An apparatus and method for varying a compression ratio of an engine having a block and a head mounted thereto. The apparatus and method includes a cylinder having a block portion and a head portion, a piston linearly movable in the block portion of the cylinder, a cylinder plug linearly movable in the head portion of the cylinder, and a valve located in the cylinder plug and operable to provide controlled fluid communication with the block portion of the cylinder.

ThreeSignal Method for Accurate Measurements of Depolarization Ratio with Lidar
NASA Technical Reports Server (NTRS)
Reichardt, Jens; Baumgart, Rudolf; McGee, Thomsa J.
20030101
A method is presented that permits the determination of atmospheric depolarizationratio profiles from three elasticbackscatter lidar signals with different sensitivity to the state of polarization of the backscattered light. The threesignal method is insensitive to experimental errors and does not require calibration of the measurement, which could cause large systematic uncertainties of the results, as is the case in the lidar technique conventionally used for the observation of depolarization ratios.

NASA Astrophysics Data System (ADS)
Imre, B.
20030401
NUMERICAL SLOPE STABILITY SIMULATIONS OF CHASMA WALLS IN VALLES MARINERIS/MARS USING A DISTINCT ELEMENT METHOD (DEM). B. Imre (1) (1) German Aerospace Center, Berlin Adlershof, bernd.imre@gmx.net The 8 to 10km depths of Valles Marineris (VM) offer excellent views into the upper Martian crust. Layering, fracturing, lithology, stratigraphy and the content of volatiles have influenced the evolution of the Valles Marineris wallslopes. But these parameters also reflect the development of VM and its wall slopes. The scope of this work is to gain understanding in these parameters by backsimulating the development of wall slopes. For that purpose, the two dimensional Particle Flow Code PFC2D has been chosen (ITASCA, version 2.00103). PFC2D is a distinct element code for numerical modelling of movements and interactions of assemblies of arbitrarily sized circular particles. Particles may be bonded together to represent a solid material. Movements of particles are unlimited. That is of importance because results of open systems with numerous unknown variables are nonunique and therefore highly path dependent. This DEM allows the simulation of whole development paths of VM walls what makes confirmation of the model more complete (e.g. Oreskes et al., Science 263, 1994). To reduce the number of unknown variables a proper (that means as simple as possible) fieldsite had to be selected. The northern wall of eastern Candor Chasma has been chosen. This wall is up to 8km high and represents a significant outcrop of the upper Martian crust. It is quite uncomplex, wellaligned and of simple morphology. Currently the work on the model is at the stage of performing the parameter study. Results will be presented via poster by the EGSMeeting.

Direct observations of the Antarctic Slope Current transport at 113°E
NASA Astrophysics Data System (ADS)
PeñaMolino, B.; McCartney, M. S.; Rintoul, S. R.
20161001
The Antarctic Slope Current (ASC), defined here as the region of westward flow along the continental slope off Antarctica, forms the southern limb of the subpolar gyres. It regulates the exchange of water across the shelf break and provides a path for interbasin westward transport. Despite its significance, the ASC remains largely unobserved around most of the Antarctic continent. Here we present direct velocity observations from a 17 month current meter moored array deployed across the continental slope between the 1000 and the 4200 m isobaths, in the southeastern Indian Ocean near 113°E. The observed timemean flow consists of a surfaceintensified jet associated with the Antarctic Slope Front (ASF) and a broader bottomintensified westward flow that extends out to approximately the 4000 m isobath and is strongest along the upper slope. The timemean transport of the ASC is 29.2 Sv. Fluctuations in the transport are large, typically exceeding the mean by a factor of 2. They are mainly due to changes in the northward extent of the current over the lower slope. However, seasonal changes in the wind also drive variations in the transport of the ASF and the flow in the upper slope. Both mean and variability are largely barotropic, thus invisible to traditional geostrophic methods.

Analysis of Local Slopes at the InSight Landing Site on Mars
NASA Astrophysics Data System (ADS)
Fergason, R. L.; Kirk, R. L.; Cushing, G.; Galuszka, D. M.; Golombek, M. P.; Hare, T. M.; HowingtonKraus, E.; Kipp, D. M.; Redding, B. L.
20171001
To evaluate the topography of the surface within the InSight candidate landing ellipses, we generated Digital Terrain Models (DTMs) at lander scales and those appropriate for entry, descent, and landing simulations, along with orthoimages of both images in each stereopair, and adirectional slope images. These products were used to assess the distribution of slopes for each candidate ellipse and terrain type in the landing site region, paying particular attention to how these slopes impact InSight landing and engineering safety, and results are reported here. Overall, this region has extremely low slopes at 1meter baseline scales and meets the safety constraints of the InSight lander. The majority of the landing ellipse has a mean slope at 1meter baselines of 3.2°. In addition, a mosaic of HRSC, CTX, and HiRISE DTMs within the final landing ellipse (ellipse 9) was generated to support entry, descent, and landing simulations and evaluations. Several methods were tested to generate this mosaic and the NASA Ames Stereo Pipeline program dem_mosaic produced the best results. For the HRSCCTXHiRISE DTM mosaic, more than 99 % of the mosaic has slopes less than 15°, and the introduction of artificially high slopes along image seams was minimized.

Analysis of local slopes at the InSight landing site on Mars
Fergason, Robin L.; Kirk, Randolph L.; Cushing, Glen; Galuszka, Donna M.; Golombek, Matthew P.; Hare, Trent M.; HowingtonKraus, Elpitha; Kipp, Devin M; Redding, Bonnie L.
20170101
To evaluate the topography of the surface within the InSight candidate landing ellipses, we generated Digital Terrain Models (DTMs) at lander scales and those appropriate for entry, descent, and landing simulations, along with orthoimages of both images in each stereopair, and adirectional slope images. These products were used to assess the distribution of slopes for each candidate ellipse and terrain type in the landing site region, paying particular attention to how these slopes impact InSight landing and engineering safety, and results are reported here. Overall, this region has extremely low slopes at 1meter baseline scales and meets the safety constraints of the InSight lander. The majority of the landing ellipse has a mean slope at 1meter baselines of 3.2°. In addition, amosaic of HRSC, CTX, and HiRISE DTMs within the final landing ellipse (ellipse9) was generated to support entry, descent, and landing simulations and evaluations. Several methods were tested to generate this mosaic and the NASA Ames Stereo Pipeline programdem_mosaicproduced the best results. For the HRSCCTXHiRISE DTM mosaic, more than 99% of the mosaic has slopes less than 15°, and the introduction of artificially high slopes along image seams was minimized.

NASA Astrophysics Data System (ADS)
Ismail, Mohd Ashraf Mohamad; Hamzah, Nur Hasliza
20170701
Rainfall has been considered as the major cause of the slope failure. The mechanism leading to slope failures included the infiltration process, surface runoff, volumetric water content and porewater pressure of the soil. This paper describes a study in which simulated rainfall events were used with 2dimensional soil column to study the response of unsaturated soil behavior based on different slope angle. The 2dimensional soil column is used in order to demonstrate the mechanism of the slope failure. These unsaturated soil were tested with four different slope (15°, 25°, 35° and 45°) and subjected to three different rainfall intensities (maximum, mean and minimum). The following key results were obtained: (1) the stability of unsaturated soil decrease as the rainwater infiltrates into the soil. Soil that initially in unsaturated state will start to reach saturated state when rainwater seeps into the soil. Infiltration of rainwater will reduce the matric suction in the soil. Matric suction acts in controlling soil shear strength. Reduction in matric suction affects the decrease in effective normal stress, which in turn diminishes the available shear strength to a point where equilibrium can no longer be sustained in the slope. (2) The infiltration rate of rainwater decreases while surface runoff increase when the soil nearly achieve saturated state. These situations cause the soil erosion and lead to slope failure. (3) The steepness of the soil is not a major factor but also contribute to slope failures. For steep slopes, rainwater that fall on the soil surface will become surface runoff within a short time compare to the water that infiltrate into the soil. While for gentle slopes, water that becomes surface runoff will move slowly and these increase the water that infiltrate into the soil.

Precipitation measurements on windswept slopes
Austin E. Helmers
19540101
Precipitation catch for three calendar years is compared for four types of gage installation on a windswept southfacing slope with a 22Â° gradient at elevation 5500 ft. The 1950 precipitation catch by (1) weighingrecording gage with the orifice and an Alter type wind shield sloped parallel to the ground surface, (2) unshielded nonrecording gage with orifice sloped...

Subsurface temperatures and geothermal gradients on the north slope of Alaska
Collett, T.S.; Bird, K.J.; Magoon, L.B.
19930101
On the North Slope of Alaska, geothermal gradient data are available from highresolution, equilibrated wellbore surveys and from estimates based on welllog identification of the base of icebearing permafrost. A total of 46 North Slope wells, considered to be in or near thermal equilibrium, have been surveyed with highresolution temperatures devices and geothermal gradients can be interpreted directly from these recorded temperature profiles. To augment the limited North Slope temperature data base, a new method of evaluating local geothermal gradients has been developed. In this method, a series of welllog picks for the base of the icebearing permafrost from 102 wells have been used, along with regional temperature constants derived from the highresolution stabilized wellbore temperature surveys, to project geothermal gradients. Geothermal gradients calculated from the highresolution temperature surveys generally agree with those projected from known icebearing permafrost depths over most of the North Slope. Values in the icebearing permafrost range from ??? 1.5??C 100 m in the Prudhoe Bay area to ??? 4.5??C 100 m in the eastcentral portion of the National Petroleum Reserve in Alaska. Geothermal gradients below the icebearing permafrost sequence range from ??? 1.6??C 100 m to ??? 5.2??C 100 m. ?? 1993.

Construction of a Dry Ash Dam with Soilbags and Slope Stability Analysis
NASA Astrophysics Data System (ADS)
Li, Hui; Song, Yingjun; Gao, Jiaorong; Li, Longhua; Zhou, Yuqi; Qi, Hui
20171201
In thermal power plants, it is necessary to build ash dams to store fly ash, which is the byproduct after the combustion of coals. To solve the problem of lacking rockfill materials in Africa, A new technology of constructing ash dams using solibags filled with local sands is proposed and the method of analyzing its slope stability is suggested. The design of the ash dam using soilbags in Lamb Thermal Power Plant of Kenya is introduced in detail. The slope stability of the soilbagsconstructed ash dam was analyzed by adopting the suggested method. The results show that the soilbags filled with ash or sands have high compressive strength, and the primary dam constructed with soilbags can effectively retain the backfill ash and the stacking dam reinforced with soilbags can stand stable even with the slope of 1:1.5.

NASA Astrophysics Data System (ADS)
Pasik, Tomasz; van der Meij, Raymond
20171201
This article presents an efficient search method for representative circular and unconstrained slip surfaces with the use of the tailored genetic algorithm. Searches for unconstrained slip planes with rigid equilibrium methods are yet uncommon in engineering practice, and little publications regarding truly free slip planes exist. The proposed method presents an effective procedure being the result of the right combination of initial population type, selection, crossover and mutation method. The procedure needs little computational effort to find the optimum, unconstrained slip plane. The methodology described in this paper is implemented using Mathematica. The implementation, along with further explanations, is fully presented so the results can be reproduced. Sample slope stability calculations are performed for four cases, along with a detailed result interpretation. Two cases are compared with analyses described in earlier publications. The remaining two are practical cases of slope stability analyses of dikes in Netherlands. These four cases show the benefits of analyzing slope stability with a rigid equilibrium method combined with a genetic algorithm. The paper concludes by describing possibilities and limitations of using the genetic algorithm in the context of the slope stability problem.

NASA Astrophysics Data System (ADS)
Wu, Chunhung
20160401
induced landslide are interesting and meaningful. Eight landsliderelated factors, including elevation, slope, aspect, geology, accumulated rainfall during 2009 Typhoon Morakot, landuse, distance to the fault, and distance to the rivers, were considered in this research. The research builds and compares the difference of the LS maps based on four methods. The average LS value from each method is 0.27 for LRBLR, 0.368 for FR, 0.553 for WOE, and 0.498 for II. The correlation analysis was conducted to identify similarities between the four LS maps. The correlation coefficients are 0.913, 0.829, 0.930, 0.756, 0.729, and 0.652 for the LRBLR vs FR, LRBLR vs WOE, FR vs WOE, LRBLR vs II, FR vs II, and WOE vs II. The research compares the model performance of four LS maps by calculating the AUC value (area under the ROC curve) and ACR value (average correctpredicted ratio). The AUC values of LS maps based on LRBLR, FR, WOE, and II methods are 0.819, 0.819, 0.822 and 0.785. The ACR values of LS maps based on LRBLR, FR, WOE, and II methods are 75.1%, 73.7%, 68.4%, and 64.2%. The results indicate that the model performance based on LRBLR method in an extreme rainfalllandslide event is better than that based on the other three methods.

Characterization of Unstable Rock Slopes Through Passive Seismic Measurements
NASA Astrophysics Data System (ADS)
Kleinbrod, U.; Burjanek, J.; Fäh, D.
20141201
Catastrophic rock slope failures have high social impact, causing significant damage to infrastructure and many casualties throughout the world each year. Both detection and characterization of rock instabilities are therefore of key importance. An analysis of ambient vibrations of unstable rock slopes might be a new alternative to the already existing methods, e.g. geotechnical displacement measurements. Systematic measurements have been performed recently in Switzerland to study the seismic response of potential rockslides concerning a broad class of slope failure mechanisms and material conditions. Small aperture seismic arrays were deployed at sites of interest for a short period of time (several hours) in order to record ambient vibrations. Each measurement setup included a reference station, which was installed on a stable part close to the instability. Recorded ground motion is highly directional in the unstable parts of the rock slope, and significantly amplified with respect to stable areas. These effects are strongest at certain frequencies, which were identified as eigenfrequencies of the unstable rock mass. In most cases the directions of maximum amplification are perpendicular to open cracks and in good agreement with the deformation directions obtained by geodetic measurements. Such unique signatures might improve our understanding of slope structure and stability. Thus we link observed vibration characteristics with available results of detailed geological characterization. This is supported by numerical modeling of seismic wave propagation in fractured media with complex topography.For example, a potential relation between eigenfrequencies and unstable rock mass volume is investigated.

Rheological model analysis on depth of toppling deformation in the antidip rock slope
NASA Astrophysics Data System (ADS)
Zheng, Da
20170401
The failure of the toppling deformation occurred in the layered rock mass, it is a kind of mode of deformation and failure, which is bent towards free direction and gradually develops into the slope under the combined forces of insitu stress, gravity, and groundwater dynamic (hydrostatic) pressure and so on. The most common toppling deformation is the toppling of ductile bending. Obtaining the developmental depth of bending deformation is of great significance for judging the development scale of the plasmodium and the stability of the slope. At present, the developmental depth of toppling deformation mainly depends on the survey and statistic of the exploration adit, or the simulation of the deformation and failure process through the numerical simulation method, there is little research on the developmental depth of toppling deformation from mechanics point of view. In this paper, with the consideration of the timesensitive characteristics of developmental process of the toppling deformation, the antidip layered slope can be considered as a multilayer superposition cantilever with fixed end and free end, bending under selfweight and interlayer stress. Under the premise of the initial stage of rheology of the rock slopes, which is considered to be the limit position of the toppling deformation and development, the Kelvin rheological model, which is usually used to describe the decay creep, is chosen to describe the timesensitive process of rock slopes. The stressstrain analysis calculation is used to obtain the timevarying expression of a certain point on the rock beam. Furthermore, taking the time to infinity, the depth of the layered rock slopes is calculated as x=4Ccosβ/[2γcosαcosβ  γ2(cos (α + β)+2sin(α + β)tanφ)*((1+n) /2+(1n) cos2α/ 2)] , which is obtained by using the strain reaches zero as the criterion of the depth at toppling deformation development limit position, combining the timevarying expression of a certain point on the beam

Caanyon Mediated CrossSlope Transport
NASA Astrophysics Data System (ADS)
Mihaly, S. F.; Cabrera De Leo, F.; Sastri, A. R.; Matabos, M.; Heesemann, M.; Ogata, B.
20171201
Three current meter and water property stations along the west coast of Vancouver Island along with video and acoustic backscatter observations are used to gain insight into mechanisms of crossslope transport. The setting is an eastern boundary current region with a active poleward flowing countercurrent. The significant effects of these currents flowing over a strongly incised continental slope along with crossslope density flows are contrasted with the seasonally varying upwelling and downwelling regime. The video and acoustic backscatter enabled by Ocean Networks Canada's NEPTUNE observatory provide a view on the materials being transported between the abyssal plain and the continental shelf.

Centrifuge Modeling of Rainfall Induced Slope Failure
NASA Astrophysics Data System (ADS)
Ling, H.; Wu, M.
20061201
Rainfall induces slope failure and debris flow which are considered as one of the major natural disasters. The scope of such failure is very large and it cannot be studied easily in the laboratory. Traditionally, small scale model tests are used to study such problem. Knowing that the behavior of soil is affected by the stress level, centrifuge modeling technique has been used to simulate more realistically full scale earth structures. In this study, two series of tests were conducted on slopes under the centrifugal field with and without the presence of rainfall. The soil used was a mixture of sand and 15 percent fines. The slopes of angle 60 degrees were prepared at optimum water content in order to achieve the maximum density. In the first series of tests, three different slope heights of 10 cm, 15 cm and 20 cm were used. The gravity was increased gradually until slope failure in order to obtain the prototype failure height. The slope model was cut after the test in order to obtain the configuration of failure surface. It was found that the slope geometry normalized by the height at failure provided unique results. Knowing the slope height or gravity at failure, the second series of tests with rainfall were conducted slightly below the critical height. That is, after attaining the desired gravity, the rainfall was induced in the centrifuge. Special nozzles were used and calibrated against different levels of gravity in order to obtain desired rainfall intensity. Five different rainfall intensities were used on the 15cm slopes at 80g and 60g, which corresponded to 12 m and 9 m slope height, respectively. The duration until failure for different rainfall intensities was obtained. Similar to the first series of tests, the slope model was cut and investigated after the test. The results showed that the failure surface was not significantly affected by the rainfall. That is, the excess pore pressure induced by rainfall generated slope failure. The prediction curves

Seismic response of rock slopes: Numerical investigations on the role of internal structure
NASA Astrophysics Data System (ADS)
Arnold, L.; Applegate, K.; Gibson, M.; Wartman, J.; Adams, S.; Maclaughlin, M.; Smith, S.; Keefer, D. K.
20131201
The stability of rock slopes is significantly influenced and often controlled by the internal structure of the slope created by such discontinuities as joints, shear zones, and faults. Under seismic conditions, these discontinuities influence both the resistance of a slope to failure and its response to dynamic loading. The dynamic response, which can be characterized by the slope's natural frequency and amplification of ground motion, governs the loading experienced by the slope in a seismic event and, therefore, influences the slope's stability. In support of the Network for Earthquake Engineering Simulation (NEES) project SeismicallyInduced Rock Slope Failure: Mechanisms and Prediction (NEESROCK), we conducted a 2D numerical investigation using the discrete element method (DEM) coupled with simple discrete fracture networks (DFNs). The intact rock mass is simulated with a bonded assembly of discrete particles, commonly referred to as the bondedparticle model (BPM) for rock. Discontinuities in the BPM are formed by the insertion of smooth, unbonded contacts along specified planes. The influence of discontinuity spacing, orientation, and stiffness on slope natural frequency and amplification was investigated with the commercially available Particle Flow Code (PFC2D). Numerical results indicate that increased discontinuity spacing has a nonlinear effect in decreasing the amplification and increasing the natural frequency of the slope. As discontinuity dip changes from subhorizontal to subvertical, the slope's level of amplification increases while the natural frequency of the slope decreases. Increased joint stiffness decreases amplification and increases natural frequency. The results reveal that internal structure has a strong influence on rock slope dynamics that can significantly change the system's dynamic response and stability during seismic loading. Financial support for this research was provided by the United States National Science Foundation (NSF

Analysis of InfiltrationSuction Response in Unsaturated Residual Soil Slope in Gelugor, Penang
NASA Astrophysics Data System (ADS)
Ashraf Mohamad Ismail, Mohd; Hasliza Hamzah, Nur; Min, Ng Soon; Hazreek Zainal Abidin, Mohd; Tajudin, Saiful Azhar Ahmad; Madun, Aziman
20180401
Rainfall infiltration on residual soil slope may impair slope stability by altering the porewater pressure in the soil. A study has been carried out on unsaturated residual soil slope in Gelugor, Penang to determine the changes in matric suction of residual soils at different depth due to rainwater infiltration. The sequence of this study includes the site investigation, field instrumentation, laboratory experiment and numerical modeling. Void ratio and porosity of soil were found to be decreasing with depth while the bulk density and dry density of soil increased due to lower porosity of soil at greater depth. Soil infiltration rate and matric suction of all depths decrease with the increase of volumetric water content as well as the degree of saturation. Numerical modeling was used to verify and predict the relationship between infiltrationsuction response and degree of saturation. Numerical models can be used to integrate the rainfall scenarios into quantitative landslide hazard assessments. Thus, development plans and mitigation measures can be designed for estimated impacts from hazard assessments based on collected data.

A qualitative comparison of fire spread models incorporating wind and slope effects
David R. Weise; Gregory S. Biging
19970101
Wind velocity and slope are two critical variables that affect wildland fire rate of spread. The effects of these variables on rate of spread are often combined in rateofspread models using vector addition. The various methods used to combine wind and slope effects have seldom been validated or compared due to differences in the models or to lack of data. In this...
 «
 8
 9
 10
 11
 12
 »
 «
 9
 10
 11
 12
 13
 »

NASA Astrophysics Data System (ADS)
Böhme, Martina; Hermanns, Reginald L.; Oppikofer, Thierry; Penna, Ivanna
20160401
Unstable rock slopes that can cause large failures of the rockavalanche type have been mapped in Norway for almost two decades. Four sites have earlier been characterized as highrisk objects based on expertise of few researchers. This resulted in installing continuous monitoring systems and setup of an earlywarning system for those four sites. Other unstable rock slopes have not been ranked related to their hazard or risk. There are ca. 300 other sites known of which 70 sites were installed for periodic deformation measurements using multiple techniques (Global Navigation Satellite Systems, extensometers, measurement bolts, and others). In 2012 a systematic hazard and risk classification system for unstable rock slopes was established in Norway and the mapping approach adapted to that in 2013. Now, the first 22 sites were classified for hazard, consequences and risk using this classification system. The selection of the first group of sites to be classified was based on an assumed high hazard or risk and importance given to the sites by Norwegian media and the public. Nine of the classified 22 unstable rock slopes are large sites that deform inhom*ogeneously or are strongly broken up in individual blocks. This suggests that different failure scenarios are possible that need to be analyzed individually. A total of 35 failure scenarios for those nine unstable rock slopes were considered. The hazard analyses were based on 9 geological parameters defined in the classification system. The classification system will be presented based on the Gamanjunni unstable rock slope. This slope has a well developed back scarp that exposes 150 m preceding displacement. The lateral limits of the unstable slope are clearly visible in the morphology and InSAR displacement data. There have been no single structures observed that allow sliding kinematically. The lower extend of the displacing rock mass is clearly defined in InSAR data and by a zone of higher rock fall activity. Yearly

Giard, JeanneMarie; Mehta, Neil; Dodge, Jennifer L; Roberts, John P; Yao, Francis Y
20180501
Rising alphafetoprotein (AFP) is a potential marker of worse prognosis after liver transplant (LT) for hepatocellular carcinoma (HCC), but prior studies relied on only 2 data points and were imprecise in assessing AFP slope. The aim of this study was to examine the association between AFP slope and postLT HCC recurrence, with AFP slope estimated from multiple data points over time. Our cohort included 336 patients undergoing LT with Model for End Stage Liver Disease exception for HCC within Milan criteria from 2003 to 2013. Most (98%) had preLT locoregional therapy. AFP slope was estimated by fitting a regression line to the AFP levels over time. The 1 and 5year postLT survivals were 94% and 77% and 1 and 5year recurrencefree probabilities were 95% and 86%, respectively. In univariate analysis, HCC recurrence was significantly associated with microvascular invasion (hazard ratio [HR], 13.1; P<0.001), tumor grade (HR, 1.8; P<0.001), pathologic stage >Milan criteria (HR, 8.9; P<0.001), 3 tumor nodules (HR, 5.5; P=0.002), AFP slope greater than 7.5 ng/mL per month (HR, 3.9; P=0.005), and female sex (HR, 2.3; P=0.01). In multivariable analysis of factors known before LT, 3 tumor nodules (HR, 7.6; P<0.001), female sex (HR, 2.5; P=0.01), and AFP slope >7.5 (HR, 3.0; P=0.03) were significantly associated with HCC recurrence. AFP slope greater than 7.5 was also associated with microvascular invasion (odds ratio, 6.8; P=0.008). AFP slope increasing greater than 7.5 ng/mL per month despite locoregional therapy is associated with postLT HCC recurrence and may serve as a surrogate for microvascular invasion. These findings support incorporating changes in the AFP into candidate selection for LT.

A Unified Fisher's Ratio Learning Method for Spatial Filter Optimization.
Li, Xinyang; Guan, c*ntai; Zhang, Haihong; Ang, Kai Keng
To detect the mental task of interest, spatial filtering has been widely used to enhance the spatial resolution of electroencephalography (EEG). However, the effectiveness of spatial filtering is undermined due to the significant nonstationarity of EEG. Based on regularization, most of the conventional stationary spatial filter design methods address the nonstationarity at the cost of the interclass discrimination. Moreover, spatial filter optimization is inconsistent with feature extraction when EEG covariance matrices could not be jointly diagonalized due to the regularization. In this paper, we propose a novel framework for a spatial filter design. With Fisher's ratio in feature space directly used as the objective function, the spatial filter optimization is unified with feature extraction. Given its ratio form, the selection of the regularization parameter could be avoided. We evaluate the proposed method on a binary motor imagery data set of 16 subjects, who performed the calibration and test sessions on different days. The experimental results show that the proposed method yields improvement in classification performance for both single broadband and filter bank settings compared with conventional nonunified methods. We also provide a systematic attempt to compare different objective functions in modeling data nonstationarity with simulation studies.To detect the mental task of interest, spatial filtering has been widely used to enhance the spatial resolution of electroencephalography (EEG). However, the effectiveness of spatial filtering is undermined due to the significant nonstationarity of EEG. Based on regularization, most of the conventional stationary spatial filter design methods address the nonstationarity at the cost of the interclass discrimination. Moreover, spatial filter optimization is inconsistent with feature extraction when EEG covariance matrices could not be jointly diagonalized due to the regularization. In this paper, we propose a novel

The Hydromechanics of Vegetation for Slope Stabilization
NASA Astrophysics Data System (ADS)
Mulyono, A.; Subardja, A.; Ekasari, I.; Lailati, M.; Sudirja, R.; Ningrum, W.
20180201
Vegetation is one of the alternative technologies in the prevention of shallow landslide prevention that occurs mostly during the rainy season. The application of plant for slope stabilization is known as bioengineering. Knowledge of the vegetative contribution that can be considered in bioengineering was the hydrological and mechanical aspects (hydromechanical). Hydrological effect of the plant on slope stability is to reduce soil water content through transpiration, interception, and evapotranspiration. The mechanical impact of vegetation on slope stability is to stabilize the slope with mechanical reinforcement of soils through roots. Vegetation water consumption varies depending on the age and density, rainfall factors and soil types. Vegetation with high ability to absorb water from the soil and release into the atmosphere through a transpiration process will reduce the pore water stress and increase slope stability, and vegetation with deep root anchoring and strong root binding was potentially more significant to maintain the stability of the slope.

Mehner, Thomas; Lischke, Betty; Scharnweber, Kristin; Attermeyer, Katrin; Brothers, Soren; Gaedke, Ursula; Hilt, Sabine; Brucet, Sandra
20180601
The density of organisms declines with size, because larger organisms need more energy than smaller ones and energetic losses occur when larger organisms feed on smaller ones. A potential expression of densitysize distributions are Normalized Biomass Size Spectra (NBSS), which plot the logarithm of biomass independent of taxonomy within bins of logarithmic organismal size, divided by the bin width. Theoretically, the NBSS slope of multitrophic communities is exactly 1.0 if the trophic transfer efficiency (TTE, ratio of production rates between adjacent trophic levels) is 10% and the predatorprey mass ratio (PPMR) is fixed at 10 4 . Here we provide evidence from four multitrophic lake food webs that empirically estimated TTEs correspond to empirically estimated slopes of the respective community NBSS. Each of the NBSS considered pelagic and benthic organisms spanning size ranges from bacteria to fish, all sampled over three seasons in 1 yr. The four NBSS slopes were significantly steeper than 1.0 (range 1.14 to 1.19, with 95% CIs excluding 1). The corresponding average TTEs were substantially lower than 10% in each of the four food webs (range 1.0% to 3.6%, mean 1.85%). The overall slope merging all biomasssize data pairs from the four systems (1.17) was almost identical to the slope predicted from the arithmetic mean TTE of the four food webs (1.18) assuming a constant PPMR of 10 4 . Accordingly, our empirical data confirm the theoretically predicted quantitative relationship between TTE and the slope of the biomasssize distribution. Furthermore, we show that benthic and pelagic organisms can be merged into a community NBSS, but future studies have yet to explore potential differences in habitatspecific TTEs and PPMRs. We suggest that community NBSS may provide valuable information on the structure of food webs and their energetic pathways, and can result in improved accuracy of TTEestimates. © 2018 by the Ecological Society of America.

Brandmaier, Andreas M.; von Oertzen, Timo; Ghisletta, Paolo; Lindenberger, Ulman; Hertzog, Christopher
20180101
Latent Growth Curve Models (LGCM) have become a standard technique to model change over time. Prediction and explanation of interindividual differences in change are major goals in lifespan research. The major determinants of statistical power to detect individual differences in change are the magnitude of true interindividual differences in linear change (LGCM slope variance), design precision, alpha level, and sample size. Here, we show that design precision can be expressed as the inverse of effective error. Effective error is determined by instrument reliability and the temporal arrangement of measurement occasions. However, it also depends on another central LGCM component, the variance of the latent intercept and its covariance with the latent slope. We derive a new reliability index for LGCM slope variance—effective curve reliability (ECR)—by scaling slope variance against effective error. ECR is interpretable as a standardized effect size index. We demonstrate how effective error, ECR, and statistical power for a likelihood ratio test of zero slope variance formally relate to each other and how they function as indices of statistical power. We also provide a computational approach to derive ECR for arbitrary interceptslope covariance. With practical use cases, we argue for the complementary utility of the proposed indices of a study's sensitivity to detect slope variance when making a priori longitudinal design decisions or communicating study designs. PMID:29755377

Database on unstable rock slopes in Norway
NASA Astrophysics Data System (ADS)
Oppikofer, Thierry; Nordahl, Bo; Bunkholt, Halvor; Nicolaisen, Magnus; Hermanns, Reginald L.; Böhme, Martina; Yugsi Molina, Freddy X.
20140501
Several large rockslides have occurred in historic times in Norway causing many casualties. Most of these casualties are due to displacement waves triggered by a rock avalanche and affecting coast lines of entire lakes and fjords. The Geological Survey of Norway performs systematic mapping of unstable rock slopes in Norway and has detected up to now more than 230 unstable slopes with significant postglacial deformation. This systematic mapping aims to detect future rock avalanches before they occur. The registered unstable rock slopes are stored in a database on unstable rock slopes developed and maintained by the Geological Survey of Norway. The main aims of this database are (1) to serve as a national archive for unstable rock slopes in Norway; (2) to serve for data collection and storage during field mapping; (3) to provide decisionmakers with hazard zones and other necessary information on unstable rock slopes for landuse planning and mitigation; and (4) to inform the public through an online map service. The database is organized hierarchically with a main point for each unstable rock slope to which several feature classes and tables are linked. This main point feature class includes several general attributes of the unstable rock slopes, such as site name, general and geological descriptions, executed works, recommendations, technical parameters (volume, lithology, mechanism and others), displacement rates, possible consequences, hazard and risk classification and so on. Feature classes and tables linked to the main feature class include the runout area, the area effected by secondary effects, the hazard and risk classification, subareas and scenarios of an unstable rock slope, field observation points, displacement measurement stations, URL links for further documentation and references. The database on unstable rock slopes in Norway will be publicly consultable through the online map service on www.skrednett.no in 2014. Only publicly relevant parts of

The ratio method: A new tool to study oneneutron halo nuclei
Capel, Pierre; Johnson, R. C.; Nunes, F. M.
20131002
Recently a new observable to study halo nuclei was introduced, based on the ratio between breakup and elastic angular cross sections. This new observable is shown by the analysis of specific reactions to be independent of the reaction mechanism and to provide nuclearstructure information of the projectile. Here we explore the details of this ratio method, including the sensitivity to binding energy and angular momentum of the projectile. We also study the reliability of the method with breakup energy. Lastly, we provide guidelines and specific examples for experimentalists who wish to apply this method.

The Problem of Alluvial Fan Slopes
NASA Astrophysics Data System (ADS)
Stock, J. D.; Schmidt, K.
20051201
Water and debris flows exiting confined valleys have a tendency to deposit sediment on steep fans. On alluvial fans, where water transport predominates, channel slopes tend to decrease downfan from ~0.08 to ~0.01 across wide ranges of climate and tectonism. Some have argued that this pattern reflects downfan grainsize fining so that higher slopes are required just to entrain coarser particles in the waters of the upper fan, while entrainment of finer grains downfan requires lower slopes (threshold hypothesis). An older hypothesis is that slope is adjusted to transport the supplied sediment load, which decreases downfan as deposition occurs (transport hypothesis). We have begun to test these hypotheses using detailed field measurements of hydraulic and sediment variables in sediment transport models. On some fans in the western U.S. we find that alluvial fan channel bankfull depths are largely 0.51.5 m at fan heads, decreasing to 0.10.2 m at distal margins. Contrary to many previous studies, we find that median gravel diameter does not change systematically along the upper 60 80% of active fan channels. So downstream gravel fining cannot explain most of the observed channel slope reduction. However, as slope declines, surface sand cover increases systematically downfan from values of <20% above fan heads to distal fan values in excess of 70%. As a result, the threshold for sediment motion might decrease systematically downfan, leading to lower slopes. However, current models of this effect alone tend to underpredict downfan slope changes. This is likely due to off channel gravel deposition. Calculations that match observed fan longprofiles require an exponential decline in gravel transport rate, so that on some fans approximately half of the load must be deposited offchannel every ~0.251.25 km downfan. This leads us to hypothesize that alluvial fan long profiles are largely statements about the rate of deposition downfan. If so, there may be climatic and

Standard line slopes as a measure of a relative matrix effect in quantitative HPLCMS bioanalysis.
Matuszewski, B K
20060118
A simple experimental approach for studying and identifying the relative matrix effect (for example "plasmatoplasma" and/or "urinetourine") in quantitative analyses by HPLCMS/MS is described. Using as a database a large number of examples of methods developed in recent years in our laboratories, the relationship between the precision of standard line slopes constructed in five different lots of a biofluid (for example plasma) and the reliability of determination of concentration of an analyte in a particular plasma lot (or subject) was examined. In addition, the precision of standard line slopes was compared when stable isotopelabeled analytes versus analogs were used as internal standards (IS). Also, in some cases, a direct comparison of standard line slopes was made when different HPLCMS interfaces (APCI versus ESI) were used for the assay of the same compound, using the same IS and the same sample preparation and chromatographic separation conditions. In selected cases, the precision of standard line slopes in five different lots of a biofluid was compared with precision values determined five times in a single lot. The results of these studies indicated that the variability of standard line slopes in different lots of a biofluid [precision of standard line slopes expressed as coefficient of variation, CV (%)] may serve as a good indicator of a relative matrix effect and, it is suggested, this precision value should not exceed 34% for the method to be considered reliable and free from the relative matrix effect liability. Based on the results presented, in order to assess the relative matrix effect in bioanalytical methods, it is recommended to perform assay precision and accuracy determination in five different lots of a biofluid, instead of repeat (n=5) analysis in the same, single biofluid lot, calculate standard line slopes and precision of these slopes, and to use <34% slope precision value as a guide for method applicability to support clinical

Response mechanism of postearthquake slopes under heavy rainfall
NASA Astrophysics Data System (ADS)
Qiu, Hongzhi; Kong, Jiming; Wang, Renchao; Cui, Yun; Huang, Senwang
20170701
This paper uses the catastrophic landslide that occurred in Zhongxing Town, Dujiangyan City, as an example to study the formation mechanism of landslides induced by heavy rainfall in the postWenchuan earthquake area. The deformation characteristics of a slope under seismic loading were investigated via a shaking table test. The results show that a large number of cracks formed in the slope due to the tensile and shear forces of the vibrations, and most of the cracks had angles of approximately 45° with respect to the horizontal. A series of flume tests were performed to show how the duration and intensity of rainfall influence the responses of the shaken and nonshaken slopes. Wetting fronts were recorded under different rainfall intensities, and the depth of rainfall infiltration was greater in the shaken slope than in the nonshaken slope because the former experienced a greater extreme rainfall intensity under the same early rainfall and rainfall duration conditions. At the beginning of the rainfall infiltration experiment, the pore water pressure in the slope was negative, and settling occurred at the top of the slope. With increasing rainfall, the pore water pressure changed from negative to positive, and cracks were observed on the back surface of the slope and the shear outlet of the landslide on the front of the slope. The shaken slope was more susceptible to crack formation than the nonshaken slope under the same rainfall conditions. A comparison of the responses of the shaken and nonshaken slopes under heavy rainfall revealed that cracks formed by earthquakes provided channels for infiltration. Soil particles in the cracks of slopes were washed away, and the pore water pressure increased rapidly, especially the transient pore water pressure in the slope caused by shortterm concentrated rainfall which decreased rock strength and slope stability.

A Laboratory Study of Slope Flows Dynamics
NASA Astrophysics Data System (ADS)
Capriati, Andrea; Cenedese, Antonio; Monti, Paolo
20031101
Slope flows currents can contribute significantly in the diurnal circulation and air quality of complex terrain regions (mountains, valleys, etc.). During the daytime, solar heating warms the valley sides, causing upslope (or anabatic) winds. In contrast, radiative cooling of the valley sides results in cold downslope (drainage or katabatic) flows, characterized by small vertical extensions (usually 10200 m) and with the typical features of dense gravity currents. In this paper, some preliminary results on slope flows obtained by means of a series of experiments conducted in the laboratory using a temperature controlled water tank are shown. Rakes of thermocouples are used to determine the temperature structure and particle tracking velocimetry is used for the velocity measurements. A simple slope consisting of a plate in which the temperature is forced via a set of Peltier Cells is used. The analysis is performed considering different slope angles, background thermal stratifications and surface heat fluxes as well. Comparisons with theoretical and empirical laws found in literature are reported.

Slope stability radar for monitoring mine walls
NASA Astrophysics Data System (ADS)
Reeves, Bryan; Noon, David A.; Stickley, Glen F.; Longstaff, Dennis
20011101
Determining slope stability in a mining operation is an important task. This is especially true when the mine workings are close to a potentially unstable slope. A common technique to determine slope stability is to monitor the small precursory movements, which occur prior to collapse. The slope stability radar has been developed to remotely scan a rock slope to continuously monitor the spatial deformation of the face. Using differential radar interferometry, the system can detect deformation movements of a rough wall with submillimeter accuracy, and with high spatial and temporal resolution. The effects of atmospheric variations and spurious signals can be reduced via signal processing means. The advantage of radar over other monitoring techniques is that it provides full area coverage without the need for mounted reflectors or equipment on the wall. In addition, the radar waves adequately penetrate through rain, dust and smoke to give reliable measurements, twentyfour hours a day. The system has been trialed at three opencut coal mines in Australia, which demonstrated the potential for realtime monitoring of slope stability during active mining operations.

A novel fabrication method for suspended highaspectratio microstructures
NASA Astrophysics Data System (ADS)
Yang, YaoJoe; Kuo, WenCheng
20051101
Suspended highaspectratio structures (suspended HARS) are widely used for MEMS devices such as microgyroscopes, microaccelerometers, optical switches and so on. Various fabrication methods, such as SOI, SCREAM, AIM, SBM and BELST processes, were proposed to fabricate HARS. However, these methods focus on the fabrication of suspended microstructures with relatively small widths of trench opening (e.g. less than 10 µm). In this paper, we propose a novel process for fabricating very highaspectratio suspended structures with large widths of trench opening using photoresist as an etching mask. By enhancing the microtrenching effect, we can easily release the suspended structure without thoroughly removing the floor polymer inside the trenches for the cases with a relatively small trench aspect ratio. All the process steps can be integrated into a singlerun singlemask ICPRIE process, which effectively reduces the process complexity and fabrication cost. We also discuss the phenomenon of corner erosion, which results in the undesired etching of silicon structures during the structurereleasing step. By using the proposed process, 100 µm thick suspended structures with the trench aspect ratio of about 20 are demonstrated. Also, the proposed process can be used to fabricate devices for applications which require large inplane displacement. This paper was orally presented in the Transducers'05, Seoul, Korea (paper ID: 3B1.3).

Downward Slope Driving Control for Electric Powered Wheelchair Based on Capacitor Regenerative Brake
NASA Astrophysics Data System (ADS)
Seki, Hirokazu; Takahashi, Yoshiaki
This paper describes a novel capacitor regenerative braking control scheme of electric powered wheelchairs for efficient driving on downward slopes. An electric powered wheelchair, which generates the driving force by electric motors, is expected to be widely used as a mobility support system for elderly people and disabled people; however the energy efficiency has to be further improved because it is driven only by battery energy. This study proposes a capacitor regenerative braking circuit and two types of velocity control schemes with variable duty ratio. The proposed regenerative braking circuit is based on the stepup/down circuit with additional resistance and connects right and left motors in series in order to obtain a larger braking power. Some driving experiments on a practical downward slope show the effectiveness of the proposed control system.

Reliability of Slope Scores for Individuals.
19830401
RDAi3I 252 RELIABILITY OF SLOPE SCORES FOR XNDIVIDUALS( U ) NAVAL i/ BIODYNAMICS LAB*NE&I ORLEANS LA R C CARTER ET AL. APR 83 NBDL93RS UNCLASSIFIED F... Neisser , 1963), search for typographical errors in prose (Schindler, 1978), and choice reaction time (Teichner, 1978) were studied with respect to the...17 Experiment 4: Letter Search Method A lettersearch task was administered to 23 subjects in the manner of Neisser (1963). Subjects were presented

Blasting methods for heterogeneous rocks in hillside openpit mines with high and steep slopes
NASA Astrophysics Data System (ADS)
Chen, Y. J.; Chang, Z. G.; Chao, X. H.; Zhao, J. F.
20170601
In the arid desert areas in Xinjiang, most limestone quarries are hillside openpit mines (OPMs) where the limestone is hard, heterogeneous, and fractured, and can be easily broken into large blocks by blasting. This study tried to find effective technical methods for blasting heterogeneous rocks in such quarries based on an investigation into existing problems encountered in actual mining at Hongshun Limestone Quarry in Xinjiang. This study provided blasting schemes for hillside OPMs with different heights and slopes. These schemes involve the use of vertical deep holes, oblique shallow holes, and downslope holebyhole sublevel or simultaneous detonation techniques. In each bench, the detonations of holes in a detonation unit occur at intervals of 2550 milliseconds. The research findings can offer technical guidance on how to blast heterogeneous rocks in hillside limestone quarries.

Sidesloped surfaces substantially affect lower limb running kinematics.
Damavandi, Mohsen; Eslami, Mansour; Pearsall, David J
20170301
Running on sidesloped surfaces is a common obstacle in the environment; however, how and to what extent the lower extremity kinematics adapt is not well known. The purpose of this study was to determine the effects of sidesloped surfaces on threedimensional kinematics of hip, knee, and ankle during stance phase of running. Ten healthy adult males ran barefoot along an inclinable runway in level (0°) and sidesloped (10° upslope and downslope inclinations, respectively) configurations. Right hip, knee, and ankle angles along with their time of occurrence were analysed using repeated measures MANOVA. Upslope hip was more adducted (p=0.015) and internally rotated (p=0.030). Knee had greater external rotations during sidesloped running at heelstrike (p=0.005), while at toeoff, it rotated externally and internally during upslope and downslope running, respectively (p=0.001). Downslope ankle had greatest plantar flexion (p=0.001). Upslope ankle had greatest eversion compared with downslope (p=0.043), while it was more externally rotated (p=0.030). These motion patterns are necessary to adjust the lower extremity length during sidesloped running. Timing differences in the kinematic events of hip adduction and external rotation, and ankle eversion were observed (p=0.006). Knowledge on these alterations is a valuable tool in adopting strategies to enhance performance while preventing injury.

High power, high signaltonoise ratio singlefrequency 1μm Brillouin allfiber laser
NASA Astrophysics Data System (ADS)
Wang, Jing; Hou, Yubin; Zhang, Qian; Jin, Dongchen; Sun, Ruoyu; Shi, Hongxing; Liu, Jiang; Wang, Pu
20160301
We demonstrate a highpower, high signaltonoise ratio singlefrequency 1 μm Brillouin allfiber laser with high slope efficiency. The Brillouin laser system consists of a highpower singlefrequency fiber laser and a singlepass Brillouin ring cavity. The highpower singlefrequency fiber laser is onestage masteroscillator power amplifier with the maximum output power of 10.33 W, the signaltonoise ratio of 50 dB and the slope efficiency of 46%. The Brillouin fiber laser is pumped by the amplified laser with a linewidth of 33 kHz and an output power of 2.61 W limited by the damage threshold of the optical isolator. By optimizing the length of the Brillouin ring cavity to 10 m, stable singlefrequency Brillouin fiber laser is obtained with 3 kHz linewidth owing to the linewidth narrowing effect. At the launched pump power of 2.15 W, the Brillouin fiber laser generates maximum output power of 1.4 W with a slope efficiency of 79% and the optical signaltonoise ratio of 77 dB.

Aerodynamic Characteristics of LowAspectRatio Wings in Close Proximity to the Ground
NASA Technical Reports Server (NTRS)
Fink, Marvin P.; Lastinger, James L.
19610101
A windtunnel investigation has been conducted to determine the effect of ground proximity on the aerodynamic characteristics of thick highly cambered rectangular wings with aspect ratios of 1. 2, 4, and 6. The results showed that, for these aspect ratios, as the ground war, approached all wings experienced increases in liftcurve slope and reductions in induced drag which resulted in increases in liftdrag ratio. Although an increase in liftcurve slope was obtained for all aspect ratios as the ground was approached, the lift coefficient at an angle of attack of 0 deg for any given aspect ratio remained nearly constant. The experimental results were in general agreement with Wieselsberger's groundeffect theory (NACA Technical Memorandum 77). As the wings approached the ground, there was an increase in static longitudinal stability at positive angles of attack. When operating in ground effect, all the wings had stability of height at positive angles of attack and instability of height at negative angles of attack. Wingtip fairings on the wings with aspect ratios of 1 and 2 produced small increases in liftdrag ratio in ground effect. End plates extending only below the chord plane on the wing with an aspect ratio of 1 provided increases in lift coefficient and in liftdrag ratio in ground effect.
 «
 9
 10
 11
 12
 13
 »
 «
 10
 11
 12
 13
 14
 »

Analytical Study of the Mechanical Behavior of Fully Grouted Bolts in Bedding Rock Slopes
NASA Astrophysics Data System (ADS)
Liu, C. H.; Li, Y. Z.
20170901
Bolting is widely used as a reinforcement means for rock slopes. The support force of a fully grouted bolt is often provided by the combination of the axial and shear forces acting at the cross section of the bolt, especially for bedding rock slopes. In this paper, load distribution and deformation behavior of the deflecting section of a fully grouted bolt were analyzed, and a structural mechanical model was established. Based on force method equations and deformation compatibility relationships, an analytical approach, describing the contribution of the axial and shear forces acting at the intersection between the bolt and the joint plane to the stability of a rock slope, was developed. Influence of the inclination of the bolt to the joint plane was discussed. Laboratory tests were conducted with different inclinations of the bolt to the joint plane. Comparisons between the proposed approach, the experimental data and a code method were made. The calculation results are in good agreement with the test data. It is shown that transverse shear resistance plays a significant role to the bolting contribution and that the bigger the dip of the bolt to the joint plane, the more significant the dowel effect. It is also shown that the design method suggested in the code overestimates the resistance of the bolt. The proposed model considering dowel effect provides a more precise description on bolting properties of bedding rock slopes than the code method and will be helpful to improve bolting design methods.

20170102
Impact craters expose the subsurface materials on steep slopes. However, these slopes often experience rockfalls and debris avalanches that keep the surface clean of dust, revealing a variety of hues, like in this enhancedcolor image, representing different rock types. The bright reddish material at the top of the crater rim is from a coating of the Martian dust. The long streamers of material are from downslope movements. Also revealed in this slope are a variety of bedrock textures, with a mix of layered and jumbled deposits. This sample is typical of the Martian highlands, with lava flows and waterlain materials depositing layers, then broken up and jumbled by many impact events. http://photojournal.jpl.nasa.gov/catalog/PIA14454

The great slipperyslope argument.
Burgess, J A
19930901
Whenever some form of beneficent killingfor example, voluntary euthanasiais advocated, the proposal is greeted with a flood of slipperyslope arguments warning of the dangers of a Nazistyle slide into genocide. This paper is an attempt systematically to evaluate arguments of this kind. Although there are slipperyslope arguments that are sound and convincing, typical formulations of the Naziinvoking argument are found to be seriously deficient both in logical rigour and in the social history and psychology required as a scholarly underpinning. As an antidote, an attempt is made both to identify some of the likely causes of genocide and to isolate some of the more modest but legitimate fears that lie behind slipperyslope arguments of this kind.

The great slipperyslope argument.
Burgess, J A
19930101
Whenever some form of beneficent killingfor example, voluntary euthanasiais advocated, the proposal is greeted with a flood of slipperyslope arguments warning of the dangers of a Nazistyle slide into genocide. This paper is an attempt systematically to evaluate arguments of this kind. Although there are slipperyslope arguments that are sound and convincing, typical formulations of the Naziinvoking argument are found to be seriously deficient both in logical rigour and in the social history and psychology required as a scholarly underpinning. As an antidote, an attempt is made both to identify some of the likely causes of genocide and to isolate some of the more modest but legitimate fears that lie behind slipperyslope arguments of this kind. PMID:8230150

Slope activity in Gale crater, Mars
Dundas, Colin M.; McEwen, Alfred S.
20150101
Highresolution repeat imaging of Aeolis Mons, the central mound in Gale crater, reveals active slope processes within tens of kilometers of the Curiosity rover. At one location near the base of northeastern Aeolis Mons, dozens of transient narrow lineae were observed, resembling features (Recurring Slope Lineae) that are potentially due to liquid water. However, the lineae faded and have not recurred in subsequent Mars years. Other smallscale slope activity is common, but has different spatial and temporal characteristics. We have not identified confirmed RSL, which Rummel et al. (Rummel, J.D. et al. [2014]. Astrobiology 14, 887–968) recommended be treated as potential special regions for planetary protection. Repeat images acquired as Curiosity approaches the base of Aeolis Mons could detect changes due to active slope processes, which could enable the rover to examine recently exposed material.

Helping Students with Mathematics Difficulties Understand Ratios and Proportions
ERIC Educational Resources Information Center
Dougherty, Barbara; Bryant, Diane Pedrotty; Bryant, Brian R.; Shin, Mikyung
20160101
Ratios and proportions are foundational to student understanding across multiple topics in mathematics and science. In mathematics, they are central to developing concepts and skills related to slope, constant rate of change, and similar figures, which are all fundamental to algebraic concepts and skills. This article examines the importance of…

StormInduced Slope Failure Susceptibility Mapping
DOT National Transportation Integrated Search
20180101
A pilot study was conducted to characterize and map the areas susceptible to slope failure using statewide available data. The objective was to determine whether it would be possible to provide slopefailure susceptibility mapping that could be used...

Hydrology of two slopes in subarctic Yukon, Canada
NASA Astrophysics Data System (ADS)
Carey, Sean K.; Woo, MingKo
19991101
Two subarctic forested slopes in central Wolf Creek basin, Yukon, were studied in 19961997 to determine the seasonal pattern of the hydrologic processes. A southfacing slope has a dense aspen forest on silty soils with seasonal frost only and a northfacing slope has open stands of black spruce and an organic layer on top of clay sediments with permafrost. Snowmelt is advanced by approximately one month on the southfacing slope due to greater radiation receipt. Meltwater infiltrates its seasonally frozen soil with low ice content, recharging the soil moisture reservoir but yielding no lateral surface or subsurface flow. Summer evaporation depletes this recharged moisture and any additional rainfall input, at the expense of surface or subsurface flow. The northfacing slope with an ice rich substrate hinders deep percolation. Snow meltwater is impounded within the organic layer to produce surface runoff in rills and gullies, and subsurface flow along pipes and within the matrix of the organic soil. During the summer, most subsurface flows are confined to the organic layer which has hydraulic conductivities orders of magnitudes larger than the underlying boulderclay. Evaporation on the northfacing slope declines as both the frost table and the water table descend in the summer. A water balance of the two slopes demonstrates that vertical processes of infiltration and evaporation dominate moisture exchanges on the southfacing slope, whereas the retardation of deep drainage by frost and by clayey soil on the permafrost slope promotes a strong lateral flow component, principally within the organic layer. These results have the important implication that permafrost slopes and organic horizons are the principal controls on streamflow generation in subarctic catchments.

Recurring slope lineae in equatorial regions of Mars
McEwen, Alfred S.; Dundas, Colin M.; Mattson, Sarah S.; Toigo, Anthony D.; Ojha, Lujendra; Wray, James J.; Chojnacki, Matthew; Byrne, Shane; Murchie, Scott L.; Thomas, Nicolas
20140101
The presence of liquid water is a requirement of habitability on a planet. Possible indicators of liquid surface water on Mars include intermittent flowlike features observed on sloping terrains. These recurring slope lineae are narrow, dark markings on steep slopes that appear and incrementally lengthen during warm seasons on lowalbedo surfaces. The lineae fade in cooler seasons and recur over multiple Mars years. Recurring slope lineae were initially reported to appear and lengthen at midlatitudes in the late southern spring and summer and are more common on equatorfacing slopes where and when the peak surface temperatures are higher. Here we report extensive activity of recurring slope lineae in equatorial regions of Mars, particularly in the deep canyons of Valles Marineris, from analysis of data acquired by the Mars Reconnaissance Orbiter. We observe the lineae to be most active in seasons when the slopes often face the sun. Expected peak temperatures suggest that activity may not depend solely on temperature. Although the origin of the recurring slope lineae remains an open question, our observations are consistent with intermittent flow of briny water. Such an origin suggests surprisingly abundant liquid water in some nearsurface equatorial regions of Mars.

A novel method for the accurate evaluation of Poisson's ratio of soft polymer materials.
Lee, JaeHoon; Lee, SangSoo; Chang, JunDong; Thompson, Mark S; Kang, DongJoong; Park, Sungchan; Park, Seonghun
20130101
A new method with a simple algorithm was developed to accurately measure Poisson's ratio of soft materials such as polyvinyl alcohol hydrogel (PVAH) with a custom experimental apparatus consisting of a tension device, a micro XY stage, an optical microscope, and a chargecoupled device camera. In the proposed method, the initial positions of the four vertices of an arbitrarily selected quadrilateral from the sample surface were first measured to generate a 2D 1storder 4node quadrilateral element for finite element numerical analysis. Next, minimum and maximum principal strains were calculated from differences between the initial and deformed shapes of the quadrilateral under tension. Finally, Poisson's ratio of PVAH was determined by the ratio of minimum principal strain to maximum principal strain. This novel method has an advantage in the accurate evaluation of Poisson's ratio despite misalignment between specimens and experimental devices. In this study, Poisson's ratio of PVAH was 0.44 ± 0.025 (n = 6) for 2.647.0% elongations with a tendency to decrease with increasing elongation. The current evaluation method of Poisson's ratio with a simple measurement system can be employed to a realtime automated visiontracking system which is used to accurately evaluate the material properties of various soft materials.

Slope Stability Analysis of Mountain Pine Beetle Impacted Areas
NASA Astrophysics Data System (ADS)
Bogenschuetz, N. M.; Bearup, L. A.; Maxwell, R. M.; Santi, P. M.
20151201
The mountain pine beetle (MPB), Dendroctonus ponderosae, has caused significant tree mortality within North America. Specifically, the MPB affects ponderosa pine and lodgepole pine forests within the Rocky Mountains with approximately 3.4 million acres of forest impacted over the past 20 years. The full impacts of such unprecedented tree mortality on hydrology and slope stability is not well understood. This work studies the affects of MPB infestation on slope instability. A largescale statistical analysis of MPB and slope stability is combined with a more indepth analysis of the factors that contribute to slope stability. These factors include: slope aspect, slope angle, root decay, regrowth and hydrologic properties, such as water table depth and soil moisture. Preliminary results show that MPB may affect a greater number of north and eastfacing slopes. This is in accordance with more water availability and a higher MPB impacted tree density on northfacing slopes which, in turn, could potentially increase the probability of slope failure. Root strength is predicted to decrease as the roots stop transpiring 34 years proceeding infestation. However, this effect on the hillslope is likely being counterbalanced by the regrowth of grasses, forbs, shrubs, and trees. In addition, the increase in water table height from the lack of transpiring trees is adding a driving force to the slopes. The combination of all these factors will be used in order to assess the effects of MPB tree mortality on slope stability.

Using Threedimensional Plant Root Architecture in Models of Shallowslope Stability
Danjon, Frédéric; Barker, David H.; Drexhage, Michael; Stokes, Alexia
20080101
Background The contribution of vegetation to shallowslope stability is of major importance in landslideprone regions. However, existing slope stability models use only limited plant root architectural parameters. This study aims to provide a chain of tools useful for determining the contribution of tree roots to soil reinforcement. Methods Threedimensional digitizing in situ was used to obtain accurate root system architecture data for mature Quercus alba in two forest stands. These data were used as input to tools developed, which analyse the spatial position of roots, topology and geometry. The contribution of roots to soil reinforcement was determined by calculating additional soil cohesion using the limit equilibrium model, and the factor of safety (FOS) using an existing slope stability model, Slip4Ex. Key Results Existing models may incorrectly estimate the additional soil cohesion provided by roots, as the spatial position of roots crossing the potential slip surface is usually not taken into account. However, most soil reinforcement by roots occurs close to the tree stem and is negligible at a distance >1·0 m from the tree, and therefore global values of FOS for a slope do not take into account local slippage along the slope. Conclusions Within a forest stand on a landslideprone slope, soil fixation by roots can be minimal between uniform rows of trees, leading to local soil slippage. Therefore, staggered rows of trees would improve overall slope stability, as trees would arrest the downward movement of soil. The chain of tools consisting of both software (free for noncommercial use) and functions available from the first author will enable a more accurate description and use of root architectural parameters in standard slope stability analyses. PMID:17766845

Analysis of Slope Limiters on Irregular Grids
NASA Technical Reports Server (NTRS)
Berger, Marsha; Aftosmis, Michael J.
20050101
This paper examines the behavior of flux and slope limiters on nonuniform grids in multiple dimensions. Many slope limiters in standard use do not preserve linear solutions on irregular grids impacting both accuracy and convergence. We rewrite some wellknown limiters to highlight their underlying symmetry, and use this form to examine the proper  ties of both traditional and novel limiter formulations on nonuniform meshes. A consistent method of handling stretched meshes is developed which is both linearity preserving for arbitrary mesh stretchings and reduces to common limiters on uniform meshes. In multiple dimensions we analyze the monotonicity region of the gradient vector and show that the multidimensional limiting problem may be cast as the solution of a linear programming problem. For some special cases we present a new directional limiting formulation that preserves linear solutions in multiple dimensions on irregular grids. Computational results using model problems and complex threedimensional examples are presented, demonstrating accuracy, monotonicity and robustness.

Keefer, D.K.
19940101
This paper describes a general method for determining the amount of earthquakeinduced landsliding that occurs in a seismically active region over time; this determination can be used as a quantitative measure of the longterm hazard from seismically triggered landslides as well as a measure of the importance of this process to regional slopeerosion rates and landscape evolution. The method uses data from historical earthquakes to relate total volume of landslide material dislodged by an earthquake to the magnitude, M, and seismic moment, M0, of the earthquake. From worldwide data, a linearregression relation between landslide volume, V, and M0 is determined as: V = M0/1018.9(?? 0.13), where V is measured in m3 and M0 is in dyncm. To determine the amount of earthquakegenerated landsliding over time, this relation is combined with data on seismicmoment release for a particular region, which may be derived from either earthquakehistory or faultslip data. The form of the M0V relation allows the rate of production of earthquakeinduced landslides over time to be determined from total rate of seismicmoment release without regard to the distribution of individual events, thus simplifying and generalizing the determination. Application of the method to twelve seismically active regions, with areas ranging from 13,275 to 2,308,000 km2, shows that erosion rates from earthquakeinduced landslides vary significantly from region to region. Of the regions studied, the highest rates were determined for the island of Hawaii, New Zealand, western New Guinea, and the San Francisco Bay region of California. Significantly lower rates were determined for Iran, Tibet, the Sierra NevadaGreat Basin region of California, and central Japan (for the time period from 715 AD to the present). Intermediate rates were determined for Peru, southern California, onshore California, Turkey, and central Japan (for the time period from 1586 AD to the present). To determine the relative, long

NASA Astrophysics Data System (ADS)
McDonald, Eric; Harrison, Bruce; Baldwin, John; Page, William; Rood, Dylan
20170401
properties indicate that the primary method of downslope transport is largely due to tree throw and faunal burrowing. Onset of slope instability at 4030 ka appears to be related to changes in vegetation with establishment of a pine dominated forest (increase in tree throw) and/or onset of local faulting. By comparison, slope stability from 3010 ka appears to be a related to the formation of a shrub dominated steppe and a decrease in tree throw. The two periods of slope erosion after 10 ka appear related to regional periods of pronounced channel incision. Results indicate that soil stratigraphy can provide a key record of slope evolution and related paleoenvironmental changes.

Analysis of Rainfall Infiltration Law in Unsaturated Soil Slope
Zhang, Guirong; Qian, Yajun; Wang, Zhangchun; Zhao, Bo
20140101
In the study of unsaturated soil slope stability under rainfall infiltration, it is worth continuing to explore how much rainfall infiltrates into the slope in a rain process, and the amount of rainfall infiltrating into slope is the important factor influencing the stability. Therefore, rainfall infiltration capacity is an important issue of unsaturated seepage analysis for slope. On the basis of previous studies, rainfall infiltration law of unsaturated soil slope is analyzed. Considering the characteristics of slope and rainfall, the key factors affecting rainfall infiltration of slope, including hydraulic properties, water storage capacity (θ s  θ r), soil types, rainfall intensities, and antecedent and subsequent infiltration rates on unsaturated soil slope, are discussed by using theory analysis and numerical simulation technology. Based on critical factors changing, this paper presents three calculation models of rainfall infiltrability for unsaturated slope, including (1) infiltration model considering rainfall intensity; (2) effective rainfall model considering antecedent rainfall; (3) infiltration model considering comprehensive factors. Based on the technology of system response, the relationship of rainfall and infiltration is described, and the prototype of regression model of rainfall infiltration is given, in order to determine the amount of rain penetration during a rain process. PMID:24672332

Analysis of rainfall infiltration law in unsaturated soil slope.
Zhang, Guirong; Qian, Yajun; Wang, Zhangchun; Zhao, Bo
20140101
In the study of unsaturated soil slope stability under rainfall infiltration, it is worth continuing to explore how much rainfall infiltrates into the slope in a rain process, and the amount of rainfall infiltrating into slope is the important factor influencing the stability. Therefore, rainfall infiltration capacity is an important issue of unsaturated seepage analysis for slope. On the basis of previous studies, rainfall infiltration law of unsaturated soil slope is analyzed. Considering the characteristics of slope and rainfall, the key factors affecting rainfall infiltration of slope, including hydraulic properties, water storage capacity (θs  θr), soil types, rainfall intensities, and antecedent and subsequent infiltration rates on unsaturated soil slope, are discussed by using theory analysis and numerical simulation technology. Based on critical factors changing, this paper presents three calculation models of rainfall infiltrability for unsaturated slope, including (1) infiltration model considering rainfall intensity; (2) effective rainfall model considering antecedent rainfall; (3) infiltration model considering comprehensive factors. Based on the technology of system response, the relationship of rainfall and infiltration is described, and the prototype of regression model of rainfall infiltration is given, in order to determine the amount of rain penetration during a rain process.

NASA Astrophysics Data System (ADS)
Kubota, T.; Aditian, A.
20141201
Deriving the analysis of rainfall data in various mountainous locations, increase in rainfall that is deemed to be induced by the global climate change is obvious in Kyushu district, western Japan. On this point of view, its long term impact on the forest slope stability is analyzed with field investigation and numerical simulation such as finite element method (FEM). On the other hand, the influence of earthquake such as cracks on the slope due to seismic vibration was also analyzed with FEM. In this case, the slope stability analysis to obtain the factor of safety "Fs" is conducted. Here, in case of the Fs > 1.0, the slope is stable. In addition, the slope stabilizing effect of the forest mainly due to the roots strength is evaluated on some unstable slopes. Simultaneously, a holistic estimation over landslide groups is conducted by comparing "Fs" on forest slopes with non forest slopes. Therefore, the following conclusions are obtained: 1) Comparing the Fs without increased rainfall from the previous decade and the one with actual rainfall, the former case is 1.04 ~1.06 times more stable than the latter. 2) On the other hand, the forest slopes are estimated to be up to approximately 1.5 to 2.5 times more stable than the slope without forest. Therefore, the slope stabilizing effect by the forest is much higher than the increasing rainfall influence i.e. the climate change effect. These results imply that an appropriate forest existence is important under the climate change condition to prevent forest slope degradation. 3) Comparing with the destabilization of the slope by seismic activities (vibration) due to the reduction of soil strength and "cracks = slope deformation" (8~9 % to 30% reduction in Fs even after an earthquake of 490gal), the influence of the long term rainfall increase on slopes (such as 1% decrease in Fs) is relatively small in the study area.

[Mechanisms of grass in slope erosion control in Loess sandy soil region of Northwest China].
Zhao, ChunHong; Gao, JianEn; Xu, Zhen
20130101
By adopting the method of simulated precipitation and from the viewpoint of slope hydrodynamics, in combining with the analysis of soil resistance to erosion, a quantitative study was made on the mechanisms of grass in controlling the slope erosion in the cross area of windwater erosion in Loess Plateau of Northwest China under different combinations of rainfall intensity and slope gradient, aimed to provide basis to reveal the mechanisms of vegetation in controlling soil erosion and to select appropriate vegetation for the soil and water conservation in Loess Plateau. The grass Astragalus adsurgens with the coverage about 40% could effectively control the slope erosion. This grass had an efficiency of more than 70% in reducing sediment, and the grass root had a greater effect than grass canopy. On bare slope and on the slopes with the grass plant or only the grass root playing effect, there existed a functional relation between the flow velocity on the slopes and the rainfall intensity and slope gradient (V = DJ(0.33 i 0.5), where V is flow velocity, D is the comprehensive coefficient which varies with different underlying surfaces, i is rainfall intensity, and J is slope gradient). Both the grass root and the grass canopy could markedly decrease the flow velocity on the slopes, and increase the slope resistance, but the effect of grass root in decreasing flow velocity was greater while the effect in increasing resistance was smaller than that of grass canopy. The effect of grass root in increasing slope resistance was mainly achieved by increasing the sediment grain resistance, while the effect of canopy was mainly achieved by increasing the slope form resistance and wave resistance. The evaluation of the soil resistance to erosion by using a conceptual model of sediment generation by overland flow indicated that the critical shear stress value of bare slope and of the slopes with the grass plant or only the grass root playing effect was 0.533, 1.672 and 0

Xiong, YanMei; Xia, HanPing; Li, ZhiAn; Cai, XiAn
20070401
Plant roots play an important role in resisting the shallow landslip and topsoil erosion of slopes by raising soil shear strength. Among the models in interpreting the mechanisms of slope reinforcement by plant roots, WuWaldron model is a widely accepted one. In this model, the reinforced soil strength by plant roots is positively proportional to average root tensile strength and root area ratio, the two most important factors in evaluating slope reinforcement effect of plant roots. It was found that soil erosion resistance increased with the number of plant roots, though no consistent quantitative functional relationship was observed between them. The increase of soil erosion resistance by plant roots was mainly through the actions of fiber roots less than 1 mm in diameter, while fiber roots enhanced the soil stability to resist water dispersion via increasing the number and diameter of soil waterstable aggregates. Fine roots could also improve soil permeability effectively to decrease runoff and weaken soil erosion.
 «
 10
 11
 12
 13
 14
 »
 «
 11
 12
 13
 14
 15
 »

Up by upwest: Is slope like north?
Weisberg, Steven M; Nardi, Daniele; Newcombe, Nora S; Shipley, Thomas F
20141001
Terrain slope can be used to encode the location of a goal. However, this directional information may be encoded using a conceptual north (i.e., invariantly with respect to the environment), or in an observerrelative fashion (i.e., varying depending on the direction one faces when learning the goal). This study examines which representation is used, whether the sensory modality in which slope is encoded (visual, kinaesthetic, or both) influences representations, and whether use of slope varies for men and women. In a square room, with a sloped floor explicitly pointed out as the only useful cue, participants encoded the corner in which a goal was hidden. Without direct sensory access to slope cues, participants used a dial to point to the goal. For each trial, the goal was hidden uphill or downhill, and the participants were informed whether they faced uphill or downhill when pointing. In support of observerrelative representations, participants pointed more accurately and quickly when facing concordantly with the hiding position. There was no effect of sensory modality, providing support for functional equivalence. Sex did not interact with the findings on modality or reference frame, but spatial measures correlated with success on the slope task differently for each sex.

NASA Technical Reports Server (NTRS)
Debogdan, C. E.
19730101
Irradiated and unirradiated tensile and fatigue specimens of AISI 310 stainless steel and Ti5Al2.5Sn were tested in the range of 100 to 10,000 cycles to failure to determine the applicability of the method of universal slopes to irradiated materials. Tensile data for both materials showed a decrease in ductility and increase in ultimate tensile strength due to irradiation. Irradiation caused a maximum change in fatigue life of only 15 to 20 percent for both materials. The method of universal slopes predicted all the fatigue data for the 310 SS (irradiated as well as unirradiated) within a life factor of 2. For the titanium alloy, 95 percent of the data was predicted within a life factor of 3.

Soil properties in highelevation ski slopes
NASA Astrophysics Data System (ADS)
Filippa, Gianluca; Freppaz, Michele; Letey, Stéphanie; Corti, Giuseppe; Cocco, Stefania; Zanini, Ermanno
20100501
The development of winter sports determines an increasing impact on the high altitude ecosystems, as a consequence of increased participation and an increasing demand of high quality standards for skiable areas. The construction of a ski slope is associated with a certain impact on soil, which varies as a function of the degree of humaninduced disturbance to the native substrata. In this work, we provide a description of the characteristics of alpine tundra skislope soils and their nutrient status, contrasted with undisturbed areas. The study site is located in the Monterosaski Resort, Aosta Valley, NW Italy (45°51' N; 7°48' E). We chose 5 sites along an altitudinal gradient between 2700 and 2200 m a.s.l.. Per each site, one plot was established on the ski slope, while a control plot was chosen under comparable topographic conditions a few meters apart. Soils were described and samples were collected and analysed for main chemicalphysical properties. In addition an evaluation of N forms, organic matter fractionation and microbial biomass was carried out. Soil depth ranged between 10 to more than 70 cm, both on the ski slope and in the undisturbed areas. A true organomineral (A) horizon was firstly identified at 2500 m a.s.l., while a weathering horizon (Bw) was detected at 2400 m a.s.l.. However, a Bw horizon thick enough to be recognised as diagnostic for shifting soil classification order from Entisols to Inceptisols (USDASoil Taxonomy) was detected only below 2400 m a.s.l.. Lithic Cryorthents were predominant in the upper part of the sequence (above 2500 m a.s.l.), both in the ski slope and the undisturbed areas; Typic Cryorthents were identified between 2500 and 2400 m a.s.l., while Inceptisols were predominant between 2400 and 2200 m a.s.l.. Chemicalphysical properties will be discussed focusing on the main differences between ski slope and undisturbed soils, as determined by the ski slope construction. Pedogenetic processes at high altitude are

Consequence assessment of large rock slope failures in Norway
NASA Astrophysics Data System (ADS)
Oppikofer, Thierry; Hermanns, Reginald L.; Horton, Pascal; Sandøy, Gro; Roberts, Nicholas J.; Jaboyedoff, Michel; Böhme, Martina; Yugsi Molina, Freddy X.
20140501
Steep glacially carved valleys and fjords in Norway are prone to many landslide types, including large rockslides, rockfalls, and debris flows. Large rockslides and their secondary effects (rockslidetriggered displacement waves, inundation behind landslide dams and outburst floods from failure of landslide dams) pose a significant hazard to the population living in the valleys and along the fjords shoreline. The Geological Survey of Norway performs systematic mapping of unstable rock slopes in Norway and has detected more than 230 unstable slopes with significant postglacial deformation. This large number necessitates prioritisation of followup activities, such as more detailed investigations, periodic displacement measurements, continuous monitoring and earlywarning systems. Prioritisation is achieved through a hazard and risk classification system, which has been developed by a panel of international and Norwegian experts (www.ngu.no/engb/hm/Publications/Reports/2012/2012029). The risk classification system combines a qualitative hazard assessment with a consequences assessment focusing on potential life losses. The hazard assessment is based on a series of nine geomorphological, engineering geological and structural criteria, as well as displacement rates, past events and other signs of activity. We present a method for consequence assessment comprising four main steps: 1. computation of the volume of the unstable rock slope; 2. runout assessment based on the volumedependent angle of reach (Fahrböschung) or detailed numerical runout modelling; 3. assessment of possible displacement wave propagation and runup based on empirical relations or modelling in 2D or 3D; and 4. estimation of the number of persons exposed to rock avalanches or displacement waves. Volume computation of an unstable rock slope is based on the sloping local base level technique, which uses a digital elevation model to create a secondorder curved surface between the mapped extent of

Estimating stochastic noise using in situ measurements from a linear wavefront slope sensor.
Bharmal, Nazim Ali; Reeves, Andrew P
20160115
It is shown how the solenoidal component of noise from the measurements of a wavefront slope sensor can be utilized to estimate the total noise: specifically, the ensemble noise variance. It is well known that solenoidal noise is orthogonal to the reconstruction of the wavefront under conditions of low scintillation (absence of wavefront vortices). Therefore, it can be retrieved even with a nonzero slope signal present. By explicitly estimating the solenoidal noise from an ensemble of slopes, it can be retrieved for any wavefront sensor configuration. Furthermore, the ensemble variance is demonstrated to be related to the total noise variance via a straightforward relationship. This relationship is revealed via the method of the explicit estimation: it consists of a small, heuristic set of four constants that do not depend on the underlying statistics of the incoming wavefront. These constants seem to apply to all situationsdata from a laboratory experiment as well as many configurations of numerical simulationso the method is concluded to be generic.

Radiolabel ratio method for measuring pulmonary clearance of intratracheal bacterial challenges
DOE Office of Scientific and Technical Information (OSTI.GOV)
LaForce, F.M.; Boose, D.S.
Calculation of bacterial clearance is a fundamental step in any study of in situ lung antibacterial defenses. A method is described whereby about 85% of a radiolabeled bacterial inoculum was consistently introduced into the bronchopulmonary tree of a mouse by the intratracheal route. Mice were then killed 1 and 4 hours later; their lungs were removed aseptically and hom*ogenized, and viable bacteria and radiolabel counts were determined. Radiolabel counts fell slowly, and more than 80% of the original radiolabel was still present in hom*ogenized lung samples from animals sacrificed 4 hours after challenge. Bacteria/isotope ratios for the bacterial inoculum andmore» hom*ogenized lung samples from animals sacrificed immediately after challenge were very similar. Bacterial clearance values were the same whether computed from bacterial counts alone or according to a radiolabel ratio method whereby the change in the bacteria/isotope ratio in ground lung aliquots was divided by a similar ratio from bacteria used to inoculate animals. Some contamination resulted from oral streptococci being swept into the bronchopulmonary free during the aspiration process. This contamination was not a problem when penicillin was incorporated into the agar and penicillinresistant strains were used for the bacterial challenges.«less

US North Slope gas and Asian LNG markets
Attanasi, E.D.
19940101
Prospects for export of liquified natural gas (LNG) from Alaska's North Slope are assessed. Projected market conditions to 2010 show that new LNG capacity beyond announced expansions will be needed to meet regional demand and that supplies will probably come from outside the region. The estimated delivered costs of likely suppliers show that Alaska North Slope gas will not be competitive. The alternative North Slope gas development strategies of transport and sale to the lower 48 states and use on the North Slope for either enhanced oil recovery or conversion to liquids are examined. The alternative options require delaying development until US gas prices increase, exhaustion of certain North Slope oil fields, or advances occur in gas to liquid fuels conversion technology. ?? 1995.

Louisiana continental slope: geologic and seismic stratigraphic framework
DOE Office of Scientific and Technical Information (OSTI.GOV)
Ray, P.K.; Cooke, D.W.
19870501
The continental slope of Louisiana from Green Canyon to Mississippi Canyon was studied by interpreting seismic CDP data and wells in the area. The slope is characterized by blocked canyon intraslope basins of various dimensions with maximum thickness of sediments in excess of 21,000 ft, rotational slump blocks and largescale submarine slides. In the subsurface, the outer shelf and upper slope show contrasting character with that of the lower slope, especially below the Sigsbee Scarp. The seismic stratigraphic units established for the deep sea area can be recognized in their entirety up to a water depth of 6000 to 5500more» ft. In shallower water salt tectonics obliterates the sequence. Fragmental records of the sequence, especially the top of Challenger boundary, have been recognized in as shallow as 2000 to 3000 ft of water. The Tertiary units often downlap and onlap directly on the Challenger unit, indicating the progradational nature of the clastic slope. The Sigsbee unit has been traced through the entire slope area and can be divided into five subunits of unique acoustical characteristics. The slope constantly regrades in response to Neogene sea level fluctuations. Loading of the shelf by deltaic deposition contributes to salt sill formation and flowage of salt over deepwater sediments on the slope during high sea level. Regressive sea is represented by slope failure, formation of largescale submarine slides, filling of blocked canyon intraslope basins which show similar seismic facies to that of Orca and Pigmy basins as reported from DSDP studies, and sporadic uplifting of salt diapirs and massifs and the formation of linear transverse salt ridges.«less

NASA Astrophysics Data System (ADS)
Yehia, Ali M.; Arafa, Reham M.; Abbas, Samah S.; Amer, Sawsan M.
20160101
Spectral resolution of cefquinome sulfate (CFQ) in the presence of its degradation products was studied. Three selective, accurate and rapid spectrophotometric methods were performed for the determination of CFQ in the presence of either its hydrolytic, oxidative or photodegradation products. The proposed ratio difference, derivative ratio and mean centering are ratio manipulating spectrophotometric methods that were satisfactorily applied for selective determination of CFQ within linear range of 5.040.0 μg mL 1. Concentration Residuals Augmented Classical Least Squares was applied and evaluated for the determination of the cited drug in the presence of its all degradation products. Traditional Partial Least Squares regression was also applied and benchmarked against the proposed advanced multivariate calibration. Experimentally designed 25 synthetic mixtures of three factors at five levels were used to calibrate and validate the multivariate models. Advanced chemometrics succeeded in quantitative and qualitative analyses of CFQ along with its hydrolytic, oxidative and photodegradation products. The proposed methods were applied successfully for different pharmaceutical formulations analyses. These developed methods were simple and costeffective compared with the manufacturer's RPHPLC method.

Rideon lawnmowers warnings: slope measurements and safetybyseparation.
Karnes, Edward W; Leonard, S David; Lenorovitz, David R
20120101
Various singlerider open vehicles, such as lawnmowers, are susceptible to overturning on slopes that are too steep for them. Warnings have included separation from the vehicles and avoiding slopes that are too steep. A recommended maximum slope is commonly 15 degrees. However, many individuals cannot evaluate slopes just by sight. Some mower manufacturers have warned about too steep slopes and have provided slope gauges for users to determine the slopes in natural settings. This article evaluated the usefulness of such gauges for users who might be expected to need to evaluate slopes and the efficacy of a separation procedure for avoiding injuries. It was concluded that neither of these were likely to be successful and suggestions are made for alternative approaches.

NASA Astrophysics Data System (ADS)
Lian, JiJian; Li, Qin; Deng, XiFei; Zhao, GaoFeng; Chen, ZuYu
20180201
In this work, toppling failure of a jointed rock slope is studied by using the distinct lattice spring model (DLSM). The gravity increase method (GIM) with a substep loading scheme is implemented in the DLSM to mimic the loading conditions of a centrifuge test. A classical centrifuge test for a jointed rock slope, previously simulated by the finite element method and the discrete element model, is simulated by using the GIMDLSM. Reasonable boundary conditions are obtained through detailed comparisons among existing numerical solutions with experimental records. With calibrated boundary conditions, the influences of the tensional strength of the rock block, cohesion and friction angles of the joints, as well as the spacing and inclination angles of the joints, on the flexural toppling failure of the jointed rock slope are investigated by using the GIMDLSM, leading to some insight into evaluating the state of flexural toppling failure for a jointed slope and effectively preventing the flexural toppling failure of jointed rock slopes.

NASA Astrophysics Data System (ADS)
Lai, Xingping; Shan, Pengfei; Cai, Meifeng; Ren, Fenhua; Tan, Wenhui
20150101
Highsteep slope stability and its optimal excavation design in Shuichang open pit iron mine were analyzed based on a large 3D physical simulation technique. An optimal excavation scheme with a relatively steeper slope angle was successfully implemented at the northwest wall between Nos. 4 and 5 exploration lines of Shuichang Iron Mine, taking into account the 3D scale effect. The physicomechanical properties of rock materials were obtained by laboratory tests conducted on sample cores from exploration drilling directly from the iron mine. A porous rocklike composite material was formed for the model, and the mechanical parameters of the material were assessed experimentally; specifically, the effect of water on the sample was quantitatively determined. We adopted an experimental setup using stiff modular applied static loading to carry out a visual excavation of the slope at a random depth. The setup was equipped with acoustic emission (AE) sensors, and the experiments were monitored by crack optical acquirement, ground penetrating radar, and closefield photogrammetry to investigate the mechanisms of rockmass destabilization in the highsteep slope. For the complex study area, the model results indicated a clear correlation between the model's destabilization resulting from slope excavation and the collected monitoring information. During the model simulation, the overall angle of the slope increased by 16 degrees in different sections. Dramatically, the modeled excavation scheme saved over 80 million tons of rock from extraction, generating enormous economic and ecological benefits.

Chen, Shunan; Ai, Xiaoyan; Dong, Tengyun; Li, Binbin; Luo, Ruihong; Ai, Yingwei; Chen, Zhaoqiong; Li, Chuanren
20160101
Cut slopes are frequently generated by construction work in hilly areas, and artificial soil is often sprayed onto them to promote ecological rehabilitation. The artificial soil properties are very important for effective management of the slopes. This paper uses fractal and moment methods to characterize soil particle size distribution (PSD) and aggregates composition. The fractal dimension (D) showed linear relationships between clay, silt, and sand contents, with coefficients of determination from 0.843 to 0.875, suggesting that using of D to evaluate the PSD of artificial soils is reasonable. The bias (CS) and peak convex (CE) coefficients showed significant correlations with structure failure rate, moisture content, and total porosity, which validated the moment method to quantitatively describe soil structure. Railway slope (RS) soil has lower organic carbon and soil moisture, and higher pH than natural slope soil. Overall, RS exhibited poor soil structure and physicochemical properties, increasing the risk of soil erosion. Hence, more effective management measures should be adopted to promote the restoration of cut slopes. PMID:26883986

NASA Astrophysics Data System (ADS)
Kim, Jae Gon
20170401
Oxidation of sulfides produces acid rock drainage (ARD) upon their exposure to oxidation environment by construction and mining activities. The ARD causes the acidification and metal contamination of soil, surface water and groundwater, the damage of plant, the deterioration of landscape and the reduction of slope stability. The revegetation of slope surface is one of commonly adopted strategies to reduce erosion and to increase slope stability. However, the revegetation of the ARD producing slope surface is frequently failed due to its high acidity and toxic metal content. We developed a revegetation method consisting of microencapsualtion and artificial soil in the laboratory. The revegetation method was applied on the ARD producing slope on which the revegetation using soil coverage and seeding was failed and monitored the plant growth for one year. The phosphate solution was applied on sulfide containing rock to form stable Fephosphate mineral on the surface of sulfide, which worked as a physical barrier to prevent contacting oxidants such as oxygen and Fe3+ ion to the sulfide surface. After the microencapsulation, two artificial soil layers were constructed. The first layer containing organic matter, dolomite powder and soil was constructed at 2 cm thickness to neutralize the rising acidic capillary water from the subsurface and to remove the dissolved oxygen from the percolating rain water. Finally, the second layer containing seeds, organic matter, nutrients and soil was constructed at 3 cm thickness on the top. After application of the method, the pH of the soil below the artificial soil layer increased and the ARD production from the rock fragments reduced. The plant growth showed an ordinary state while the plant died two month after germination for the previous revegetation trial. No soil erosion occurred from the slope during the one year field test.

Unsteady seepage flow over sloping beds in response to multiple localized recharge
NASA Astrophysics Data System (ADS)
Bansal, Rajeev K.
20170501
New generalized solutions of linearized Boussinesq equation are derived to approximate the dynamic behavior of subsurface seepage flow induced by multiple localized timevarying recharges over sloping ditchdrain aquifer system. The mathematical model is based on extended DupuitForchheimer assumption and treats the spatial location of recharge basins as additional parameter. Closed form analytic expressions for spatiotemporal variations in water head distribution and discharge rate into the drains are obtained by solving the governing flow equation using eigenvalueeigenfunction method. Downward and zerosloping aquifers are treated as special cases of main results. A numerical example is used for illustration of combined effects of various parameters such as spatial coordinates of the recharge basin, aquifer's bed slope, and recharge rate on the dynamic profiles of phreatic surface.

Human gene therapy and slippery slope arguments.
McGleenan, T
19950101
Any suggestion of altering the genetic makeup of human beings through gene therapy is quite likely to provoke a response involving some reference to a 'slippery slope'. In this article the author examines the topography of two different types of slippery slope argument, the logical slippery slope and the rhetorical slippery slope argument. The logical form of the argument suggests that if we permit somatic cell gene therapy then we are committed to accepting germ line gene therapy in the future because there is no logically sustainable distinction between them. The rhetorical form posits that allowing somatic cell therapy now will be taking the first step on a slippery slope which will ultimately lead to the type of genocide perpetrated by the Nazis. The author tests the validity of these lines of argument against the facts of human gene therapy and concludes that because of their dependence on probabilities that cannot be empirically proven they should be largely disregarded in the much more important debate on moral linedrawing in gene therapy. PMID:8778459

Human gene therapy and slippery slope arguments.
McGleenan, T
19951201
Any suggestion of altering the genetic makeup of human beings through gene therapy is quite likely to provoke a response involving some reference to a 'slippery slope'. In this article the author examines the topography of two different types of slippery slope argument, the logical slippery slope and the rhetorical slippery slope argument. The logical form of the argument suggests that if we permit somatic cell gene therapy then we are committed to accepting germ line gene therapy in the future because there is no logically sustainable distinction between them. The rhetorical form posits that allowing somatic cell therapy now will be taking the first step on a slippery slope which will ultimately lead to the type of genocide perpetrated by the Nazis. The author tests the validity of these lines of argument against the facts of human gene therapy and concludes that because of their dependence on probabilities that cannot be empirically proven they should be largely disregarded in the much more important debate on moral linedrawing in gene therapy.

20100325
Dark slope streaks, like the ones in this unnamed crater in Terra Sabaea, are believed to be formed when surface dust is displaced and the darker rock below is exposed. Rocks falling due to gravity likely formed these streaks.

Gonthier, Gerard
20070101
A graphical method that uses continuous waterlevel and barometricpressure data was developed to estimate barometric efficiency. A plot of nearly continuous water level (on the yaxis), as a function of nearly continuous barometric pressure (on the xaxis), will plot as a line curved into a series of connected elliptical loops. Each loop represents a barometricpressure fluctuation. The negative of the slope of the major axis of an elliptical loop will be the ratio of waterlevel change to barometricpressure change, which is the sum of the barometric efficiency plus the error. The negative of the slope of the preferred orientation of many elliptical loops is an estimate of the barometric efficiency. The slope of the preferred orientation of many elliptical loops is approximately the median of the slopes of the major axes of the elliptical loops. If waterlevel change that is not caused by barometricpressure change does not correlate with barometricpressure change, the probability that the error will be greater than zero will be the same as the probability that it will be less than zero. As a result, the negative of the median of the slopes for many loops will be close to the barometric efficiency. The graphical method provided a rapid assessment of whether a well was affected by barometricpressure change and also provided a rapid estimate of barometric efficiency. The graphical method was used to assess which wells at Air Force Plant 6, Marietta, Georgia, had water levels affected by barometricpressure changes during a 2003 constantdischarge aquifer test. The graphical method was also used to estimate barometric efficiency. Barometricefficiency estimates from the graphical method were compared to those of four other methods: average of ratios, median of ratios, Clark, and slope. The two methods (the graphical and medianofratios methods) that used the median values of waterlevel change divided by barometricpressure change appeared to be most resistant to

Relation between selforganized criticality and grain aspect ratio in granular piles
NASA Astrophysics Data System (ADS)
Denisov, D. V.; Villanueva, Y. Y.; Lőrincz, K. A.; May, S.; Wijngaarden, R. J.
20120501
We investigate experimentally whether selforganized criticality (SOC) occurs in granular piles composed of different grains, namely, rice, lentils, quinoa, and mung beans. These four grains were selected to have different aspect ratios, from oblong to oblate. As a function of aspect ratio, we determined the growth (β) and roughness (α) exponents, the avalanche fractal dimension (D), the avalanche size distribution exponent (τ), the critical angle (γ), and its fluctuation. At superficial inspection, three types of grains seem to have powerlawdistributed avalanches with a welldefined τ. However, only rice is truly SOC if we take three criteria into account: a powerlawshaped avalanche size distribution, finite size scaling, and a universal scaling relation relating characteristic exponents. We study SOC as a spatiotemporal fractal; in particular, we study the spatial structure of criticality from local observation of the slope angle. From the fluctuation of the slope angle we conclude that greater fluctuation (and thus bigger avalanches) happen in piles consisting of grains with larger aspect ratio.
 «
 11
 12
 13
 14
 15
 »
 «
 12
 13
 14
 15
 16
 »

NASA Astrophysics Data System (ADS)
Gopp, N. V.; Nechaeva, T. V.; Savenkov, O. A.; Smirnova, N. V.; Smirnov, V. V.
20170101
The relationships between the morphometric parameters (MPs) of topography calculated on the basis of digital elevation model (ASTER GDEM, 30 m) and the properties of the plow layer of agrogray soils on a slope were analyzed. The contribution of MPs to the spatial variability of the soil moisture reached 42%; to the content of physical clay (<0.01 mm particles), 59%; to the humus content, 46%; to the total nitrogen content, 31%; to the content of nitrate nitrogen, 28%; to the content of mobile phosphorus, 40%; to the content of exchangeable potassium, 45%; to the content of exchangeable calcium, 67%; to the content of exchangeable magnesium, 40%; and to the soil pH, 42%. A comparative analysis of the plow layer within the eluvial and transitional parts of the slope was performed with the use of geomorphometric methods and digital soil mapping. The regression analysis showed statistically significant correlations between the properties of the plow layer and the MPs describing surface runoff, geometric forms of surface, and the soil temperature regime.

NASA Technical Reports Server (NTRS)
Hess, Robert V; Gardner, Clifford S
19470101
By using the PrandtlGlauert method that is valid for threedimensional flow problems, the value of the maximum incremental velocity for compressible flow about thin ellipsoids at zero angle of attack is calculated as a function of the Mach number for various aspect ratios and thickness ratios. The critical Mach numbers of the various ellipsoids are also determined. The results indicate an increase in critical Mach number with decrease in aspect ratio which is large enough to explain experimental results on lowaspectratio wings at zero lift.

Conceptualizations of Slope: A Review of State Standards
ERIC Educational Resources Information Center
Stanton, Michael; MooreRusso, Deborah
20120101
Since slope is a fundamental topic that is embedded throughout the U.S. secondary school curriculum, this study examined standards documents for all 50 states to determine how they address the concept of slope. The study used eleven conceptualizations of slope as categories to classify the material in the documents. The findings indicate that all…

Hippocampal place cell encoding of sloping terrain.
Porter, Blake S; Schmidt, Robert; Bilkey, David K
20180521
Effective navigation relies on knowledge of one's environment. A challenge to effective navigation is accounting for the time and energy costs of routes. Irregular terrain in ecological environments poses a difficult navigational problem as organisms ought to avoid effortful slopes to minimize travel costs. Route planning and navigation have previously been shown to involve hippocampal place cells and their ability to encode and store information about an organism's environment. However, little is known about how place cells may encode the slope of space and associated energy costs as experiments are traditionally carried out in flat, horizontal environments. We set out to investigate how dorsalCA1 place cells in rats encode systematic changes to the slope of an environment by tilting a shuttle box from flat to 15° and 25° while minimizing external cue change. Overall, place cell encoding of tilted space was as robust as their encoding of flat ground as measured by traditional place cell metrics such as firing rates, spatial information, coherence, and field size. A large majority of place cells did, however, respond to slope by undergoing partial, complex remapping when the environment was shifted from one tilt angle to another. The propensity for place cells to remap did not, however, depend on the vertical distance the field shifted. Changes in slope also altered the temporal coding of information as measured by the rate of theta phase precession of place cell spikes, which decreased with increasing tilt angles. Together these observations indicate that place cells are sensitive to relatively small changes in terrain slope and that terrain slope may be an important source of information for organizing place cell ensembles. The terrain slope information encoded by place cells could be utilized by efferent regions to determine energetically advantageous routes to goal locations. This article is protected by copyright. All rights reserved. © 2018 Wiley

A new hybrid double divisor ratio spectra method for the analysis of ternary mixtures
NASA Astrophysics Data System (ADS)
Youssef, Rasha M.; Maher, Hadir M.
20081001
A new spectrophotometric method was developed for the simultaneous determination of ternary mixtures, without prior separation steps. This method is based on convolution of the double divisor ratio spectra, obtained by dividing the absorption spectrum of the ternary mixture by a standard spectrum of two of the three compounds in the mixture, using combined trigonometric Fourier functions. The magnitude of the Fourier function coefficients, at either maximum or minimum points, is related to the concentration of each drug in the mixture. The mathematical explanation of the procedure is illustrated. The method was applied for the assay of a model mixture consisting of isoniazid (ISN), rifampicin (RIF) and pyrazinamide (PYZ) in synthetic mixtures, commercial tablets and human urine samples. The developed method was compared with the double divisor ratio spectra derivative method (DDRD) and derivative ratio spectrazerocrossing method (DRSZ). Linearity, validation, accuracy, precision, limits of detection, limits of quantitation, and other aspects of analytical validation are included in the text.

Effect of regional slope on drainage networks
NASA Astrophysics Data System (ADS)
Phillips, Loren F.; Schumm, S. A.
19870901
Drainage networks that develop under conditions of no structural control and hom*ogeneous lithology are generally dendritic, depending upon the shape and inclination of the surface on which they form. An experimental study was designed to investigate the effect of an increase of slope on the evolution and development of dendritic drainage patterns. As slope steepens, the pattern changes from dendritic at 1% slope, to subdendritic at 2%, to subparallel at 3%, to parallel at 5% and higher. The change from a dendritictype pattern to a paralleltype pattern occurs at a low slope, between 2% and 3%, and primary channel junction angles decrease abruptly from about 60° to 43°. *Present address: U.S. Army Environmental Hygiene Agency, Attn: HSHBMEWM, Aberdeen Proving Ground, Maryland 210105422

Honda, Michitaka
20140401
Several improvements were implemented in the edge method of presampled modulation transfer function measurements (MTFs). The estimation technique for edge angle was newly developed by applying an algorithm for principal components analysis. The error in the estimation was statistically confirmed to be less than 0.01 even in the presence of quantum noise. Secondly, the geometrical edge slope was approximated using a rationalized number, making it possible to obtain an oversampled edge response function (ESF) with equal intervals. Thirdly, the final MTFs were estimated using the average of multiple MTFs calculated for local areas. This averaging operation eliminates the errors caused by the rationalized approximation. Computersimulated images were used to evaluate the accuracy of our method. The relative error between the estimated MTF and the theoretical MTF at the Nyquist frequency was less than 0.5% when the MTF was expressed as a sinc function. For MTFs representing an indirect detector and phasecontrast detector, good agreement was also observed for the estimated MTFs for each. The high accuracy of the MTF estimation was also confirmed, even for edge angles of around 10 degrees, which suggests the potential for simplification of the measurement conditions. The proposed method could be incorporated into an automated measurement technique using a software application.

Design of Rock Slope Reinforcement: An Himalayan Case Study
NASA Astrophysics Data System (ADS)
Tiwari, Gaurav; Latha, Gali Madhavi
20160601
The stability analysis of the two abutment slopes of a railway bridge proposed at about 359 m above the ground level, crossing a river and connecting two hill faces in the Himalayas, India, is presented. The bridge is located in a zone of high seismic activity. The rock slopes are composed of a heavily jointed rock mass and the spacing, dip and dip direction of joint sets are varying at different locations. Geological mapping was carried out to characterize all discontinuities present along the slopes. Laboratory and field investigations were conducted to assess the geotechnical properties of the intact rock, rock mass and joint infill. Stability analyses of these rock slopes were carried out using numerical programmes. Loads from the foundations resting on the slopes and seismic accelerations estimated from sitespecific ground response analysis were considered. The proposed slope profile with several berms between successive foundations was simulated in the numerical model. An equivalent continuum approach with Hoek and Brown failure criterion was initially used in a finite element model to assess the global stability of the slope abutments. In the second stage, finite element analysis of rock slopes with all joint sets with their orientations, spacing and properties explicitly incorporated into the numerical model was taken up using continuum with joints approach. It was observed that the continuum with joints approach was able to capture the local failures in some of the slope sections, which were verified using wedge failure analysis and stereographic projections. Based on the slope deformations and failure patterns observed from the numerical analyses, rock anchors were designed to achieve the target factors of safety against failure while keeping the deformations within the permissible limits. Detailed design of rock anchors and comparison of the stability of slopes with and without reinforcement are presented.

THE FUNCTIONAL ROLES OF MUSCLES DURING SLOPED WALKING
Pickle, Nathaniel T.; Grabowski, Alena M.; Auyang, Arick G.; Silverman, Anne K.
20160101
Sloped walking is biomechanically different from levelground walking, as evidenced by changes in joint kinematics and kinetics. However, the changes in muscle functional roles underlying these altered movement patterns have not been established. In this study, we developed a total of 273 muscleactuated simulations to assess muscle functional roles, quantified by induced body centerofmass accelerations and trunk and leg power, during walking on slopes of 0°, ±3°, ±6°, and ±9° at 1.25 m/s. The soleus and gastrocnemius both provided greater forward acceleration of the body parallel to the slope at +9° compared to level ground (+126% and +66%, respectively). However, while the power delivered to the trunk by the soleus varied with slope, the magnitude of net power delivered to the trunk and ipsilateral leg by the biarticular gastrocnemius was similar across all slopes. At +9°, the hip extensors absorbed more power from the trunk (230% hamstrings, 140% gluteus maximus) and generated more power to both legs (200% hamstrings, 160% gluteus maximus) compared to level ground. At −9°, the knee extensors (rectus femoris and vasti) accelerated the body upward perpendicular to the slope at least 50% more and backward parallel to the slope twice as much as on level ground. In addition, the knee extensors absorbed greater amounts of power from the ipsilateral leg on greater declines to control descent. Future studies can use these results to develop targeted rehabilitation programs and assistive devices aimed at restoring sloped walking ability in impaired populations. PMID:27553849

Carbon mineralization in Laptev and East Siberian sea shelf and slope sediment
NASA Astrophysics Data System (ADS)
Brüchert, Volker; Bröder, Lisa; Sawicka, Joanna E.; Tesi, Tommaso; Joye, Samantha P.; Sun, Xiaole; Semiletov, Igor P.; Samarkin, Vladimir A.
20180101
The Siberian Arctic Sea shelf and slope is a key region for the degradation of terrestrial organic material transported from the organiccarbonrich permafrost regions of Siberia. We report on sediment carbon mineralization rates based on O2 microelectrode profiling; intact sediment core incubations; 35Ssulfate tracer experiments; porewater dissolved inorganic carbon (DIC); δ13CDIC; and iron, manganese, and ammonium concentrations from 20 shelf and slope stations. This data set provides a spatial overview of sediment carbon mineralization rates and pathways over large parts of the outer Laptev and East Siberian Arctic shelf and slope and allows us to assess degradation rates and efficiency of carbon burial in these sediments. Rates of oxygen uptake and iron and manganese reduction were comparable to temperate shelf and slope environments, but bacterial sulfate reduction rates were comparatively low. In the topmost 50 cm of sediment, aerobic carbon mineralization dominated degradation and comprised on average 84 % of the depthintegrated carbon mineralization. Oxygen uptake rates and anaerobic carbon mineralization rates were higher in the eastern East Siberian Sea shelf compared to the Laptev Sea shelf. DIC / NH4+ ratios in pore waters and the stable carbon isotope composition of remineralized DIC indicated that the degraded organic matter on the Siberian shelf and slope was a mixture of marine and terrestrial organic matter. Based on dual endmember calculations, the terrestrial organic carbon contribution varied between 32 and 36 %, with a higher contribution in the Laptev Sea than in the East Siberian Sea. Extrapolation of the measured degradation rates using isotope endmember apportionment over the outer shelf of the Laptev and East Siberian seas suggests that about 16 Tg C yr1 is respired in the outer shelf seafloor sediment. Of the organic matter buried below the oxygen penetration depth, between 0.6 and 1.3 Tg C yr1 is degraded by anaerobic processes

Ambient vibrations of unstable rock slopes  insights from numerical modeling
NASA Astrophysics Data System (ADS)
Burjanek, Jan; Kleinbrod, Ulrike; Fäh, Donat
20170401
The recent events in Nepal (2015 M7.8 Gorkha) and New Zealand (2016 M7.8 Kaikoura) highlighted the importance of earthquakeinduced landslides, which caused significant damages. Moreover, landslide created dams present a potential developing hazard. In order to reduce the costly consequences of such events it is important to detect and characterize earthquake susceptible rock slope instabilities before an event, and to take mitigation measures. For the characterisation of instable slopes, acquisition of ambient vibrations might be a new alternative to the already existing methods. We present both observations and 3D numerical simulations of the ambient vibrations of unstable slopes. In particular, models of representative real sites have been developed based on detailed terrain mapping and used for the comparison between synthetics and observations. A finitedifference code has been adopted for the seismic wave propagation in a 3D inhom*ogeneous viscoelastic media with irregular free surface. It utilizes a curvilinear grid for a precise modeling of curved topography and local mesh refinement to make computational mesh finer near the free surface. Topographic site effects, controlled merely by the shape of the topography, do not explain the observed seismic response. In contrast, steeplydipping compliant fractures have been found to play a key role in fitting observations. Notably, the synthetized response is controlled by inertial mass of the unstable rock, and by stiffness, depth and network density of the fractures. The developed models fit observed extreme amplification levels (factors of 70!) and show directionality as well. This represents a possibility to characterize slope structure and infer depth or volume of the slope instability from the ambient noise recordings in the future.

NASA Technical Reports Server (NTRS)
Stanley, Douglas O.; Unal, Resit; Joyner, C. R.
19920101
The application of advanced technologies to future launch vehicle designs would allow the introduction of a rocketpowered, singlestagetoorbit (SSTO) launch system early in the next century. For a selected SSTO concept, a dual mixture ratio, staged combustion cycle engine that employs a number of innovative technologies was selected as the baseline propulsion system. A series of parametric trade studies are presented to optimize both a dual mixture ratio engine and a single mixture ratio engine of similar design and technology level. The effect of varying liftoff thrusttoweight ratio, engine mode transition Mach number, mixture ratios, area ratios, and chamber pressure values on overall vehicle weight is examined. The sensitivity of the advanced SSTO vehicle to variations in each of these parameters is presented, taking into account the interaction of each of the parameters with each other. This parametric optimization and sensitivity study employs a Taguchi design method. The Taguchi method is an efficient approach for determining nearoptimum design parameters using orthogonal matrices from design of experiments (DOE) theory. Using orthogonal matrices significantly reduces the number of experimental configurations to be studied. The effectiveness and limitations of the Taguchi method for propulsion/vehicle optimization studies as compared to traditional singlevariable parametric trade studies is also discussed.

Restitution slope is principally determined by steadystate action potential duration
Shattock, Michael J.; Park, Kyung Chan; Yang, HsiangYu; Lee, Angela W. C.; Niederer, Steven; MacLeod, Kenneth T.
20170101
Aims The steepness of the action potential duration (APD) restitution curve and local tissue refractoriness are both thought to play important roles in arrhythmogenesis. Despite this, there has been little recognition of the apparent association between steadystate APD and the slope of the restitution curve. The objective of this study was to test the hypothesis that restitution slope is determined by APD and to examine the relationship between restitution slope, refractoriness and susceptibility to VF. Methods and results Experiments were conducted in isolated hearts and ventricular myocytes from adult guinea pigs and rabbits. Restitution curves were measured under control conditions and following intervention to prolong (clofilium, veratridine, bretylium, low [Ca]e, chronic transverse aortic constriction) or shorten (catecholamines, rapid pacing) ventricular APD. Despite markedly differing mechanisms of action, all interventions that prolonged the action potential led to a steepening of the restitution curve (and vice versa). Normalizing the restitution curve as a % of steadystate APD abolished the difference in restitution curves with all interventions. Effects on restitution were preserved when APD was modulated by current injection in myocytes pretreated with the calcium chelator BAPTAAM – to abolish the intracellular calcium transient. The nonlinear relation between APD and the rate of repolarization of the action potential is shown to underpin the common influence of APD on the slope of the restitution curve. Susceptibility to VF was found to parallel changes in APD/refractoriness, rather than restitution slope. Conclusion(s) Steadystate APD is the principal determinant of the slope of the ventricular electrical restitution curve. In the absence of postrepolarization refractoriness, factors that prolong the action potential would be expected to steepen the restitution curve. However, concomitant changes in tissue refractoriness act to reduce

Mars Exploration Rover Landing Site Hectometer Slopes
NASA Astrophysics Data System (ADS)
Haldemann, A. F.; Anderson, F. S.
20021201
The Mars Exploration Rover (MER) airbag landing system imposes a maximum slope of 5 degrees over 100 m lengthscales. This limit avoids dangerous changes in elevation over the horizontal travel distance of the lander on its parachute between the time of the last radar altimeter detection of the surface and the time the retrorockets fire and the bridle to the airbags is cut. Stereo imagery from the MGS MOC can provide information at this length scale, but MOC stereo coverage is sparse, even when targeted to MER landing sites. Additionally, MGS spacecraft stability issues affect the DEMs at precisely the hectometric lengthscale1. The MOLA instrument provides global coverage pulsewidth measurements2 over a single MOLApulse footprint, which is about 100 m in diameter. However, the pulse spread only provides an upper bound on the 100 m slope. We chose another approach. We sample the interpulse rootmeansquare (RMS) height deviations for MOLA track segments restricted to pixels of 0.1 deg latitude by 0.1 deg longitude. Then, under the assumption of selfaffine topography, we determine the scaledependence of the RMS deviations and extrapolate that behavior over the range of 300 m to 1.2 km downward to the 100 m scale. Shepard et al.3 clearly summarize the statistical properties of the RMS deviation (noting that it also goes by the name structure function, variogram or Allan deviation), and we follow their nomenclature. The RMS deviation is a useful measure in that it can be directly converted to RMSslope for a given lengthscale. We map the results of this selfaffine extrapolation method for each of the proposed MER landing sites as well as Viking Lander 1 (VL1) and Pathfiner (MPF). In order of decreasing average hectometer RMSslopes, Melas (about 4.5 degrees) > Elysium EP80 > Gusev > MPF > Elysium EP78 > VL1 > Athabasca > Isidis > Hematite (about 1 degree). We also map the scaling parameter (Hurst exponent); its behavior in the MER landing site regions is

An identification method for damping ratio in rotor systems
NASA Astrophysics Data System (ADS)
Wang, Weimin; Li, Qihang; Gao, Jinji; Yao, Jianfei; Allaire, Paul
20160201
Centrifugal compressor testing with magnetic bearing excitations is the last step to assure the compressor rotordynamic stability in the designed operating conditions. To meet the challenges of stability evaluation, a new method combining the rational polynomials method (RPM) with the weighted instrumental variables (WIV) estimator to fit the directional frequency response function (dFRF) is presented. Numerical simulation results show that the method suggested in this paper can identify the damping ratio of the first forward and backward modes with high accuracy, even in a severe noise environment. Experimental tests were conducted to study the effect of different bearing configurations on the stability of rotor. Furthermore, two example centrifugal compressors (a ninestage straightthrough and a sixstage backtoback) were employed to verify the feasibility of identification method in industrial configurations as well.

Surface energy fluxes on four slope sites during FIFE 1988
NASA Technical Reports Server (NTRS)
Nie, D.; DemetriadesShah, T.; Kanemasu, E. T.
19920101
Four slopes (facing north, south, east, and west) in the Konza Prairie Research Natural Area were selected to study the effect of topography on surface energy balance and other micrometeorological variables. Energy fluxes, air temperature, and vapor pressure were measured on the slopes throughout the 1988 growing season. Net radiation was highest on the south facing slope and lowest on the north facing slope, and the difference was more than 150 W/sq m (2030 percent) at solar noon. For daily averages the difference was about 25 W/sq m (15 percent) early in the season and increased to about 60 W/sq m (3050 percent) in September. Soil heat fluxes were similar for all the slopes. The absolute values of sensible heat flux were consistently lower on the north facing slope compared with other slopes. The south facing slope had the greatest daytoday fluctuation in latent heat flux as a result of the interaction of net radiation, soil moisture, and green leaf area. Differences were found in the partitioning of the available energy among the slopes, and the north facing slope had a higher percentage of energy dissipated into latent heat flux. The north facing slope had higher air temperatures during the day and higher vapor pressures both during the day and at night when the wind was from the south.

Sloping fan travertine, Belen, New Mexico, USA
NASA Astrophysics Data System (ADS)
Cook, Megan; Chafetz, Henry S.
20170501
Pliocene to Quaternary age travertines are very wellexposed in quarries near Belen, New Mexico, U.S.A., on the western edge of the Rio Grande Rift system. A series of hillside springs produced travertine tongues tens of meters thick and hundreds of meters long. The accumulations represent deposits from individual springs as well as the amalgamation of deposits. The overall architecture is predominantly composed of sloping fans with a smaller component of terrace mounds. The sloping fan deposits commonly have a dip of < 10°, however, they range from horizontal to near vertical. Individual strata display significant changes in depositional dip, beds pinch and swell, and some are completely truncated. Centimeter to meter scale terrace mounds exhibit the common stairstep morphology. As a consequence of vertical accretion in the pools, terrace mounds morphed into sloping fans. The travertine is composed of a variety of commonly reported constituents, i.e., centimeter thick laminae of bacterial shrubs and oncoids, foam rock, sheets and rafts, and finely crystalline crusts that occur throughout the sloping fan and terrace mound accumulations. Sheets and rafts formed as precipitates in pools on the surfaces of the fans and terraces as well as spelean deposits on the water surfaces of pools within cavities in the overall accumulation. Thus, the spelean rafts provide valuable indicators of original horizontality in the sloping fan strata. In addition, intraformational breccias, composed of locally tornup travertine intraclastic boulders and deposited in with other travertine, and extraformational breccias, composed of tornup travertine intraclasts mixed with siliciclastic fines and sand and Paleozoic limestone clasts transported downslope from higher on the hillside, are a common constituent in the sloping fan accumulation. The Belen travertines provide a very wellexposed example of sloping fan travertines and may provide relevant data with regard to the subsurface

Yehia, Ali M; Arafa, Reham M; Abbas, Samah S; Amer, Sawsan M
20160115
Spectral resolution of cefquinome sulfate (CFQ) in the presence of its degradation products was studied. Three selective, accurate and rapid spectrophotometric methods were performed for the determination of CFQ in the presence of either its hydrolytic, oxidative or photodegradation products. The proposed ratio difference, derivative ratio and mean centering are ratio manipulating spectrophotometric methods that were satisfactorily applied for selective determination of CFQ within linear range of 5.040.0 μg mL(1). Concentration Residuals Augmented Classical Least Squares was applied and evaluated for the determination of the cited drug in the presence of its all degradation products. Traditional Partial Least Squares regression was also applied and benchmarked against the proposed advanced multivariate calibration. Experimentally designed 25 synthetic mixtures of three factors at five levels were used to calibrate and validate the multivariate models. Advanced chemometrics succeeded in quantitative and qualitative analyses of CFQ along with its hydrolytic, oxidative and photodegradation products. The proposed methods were applied successfully for different pharmaceutical formulations analyses. These developed methods were simple and costeffective compared with the manufacturer's RPHPLC method. Copyright © 2015 Elsevier B.V. All rights reserved.

Area utilization efficiency of a sloping heliostat system for solar concentration.
Wei, L Y
19830215
Area utilization efficiency (AUE) is formulated for a sloping heliostat system facing any direction. The effects of slope shading, incidence factor, sun shading, and tower blocking by the mirrors are all taken into account. Our results show that annually averaged AUEs calculated for heliostat systems (1) increase with tower height at low slope angles but less rapidly at high slopes, (2) increase monotonically with slope angle and saturate at large slopes for systems facing due south, (3) reach a maximum at a certain slope for systems facing other directions than due south, and (4) drop sharply at slopes greater than a certain value for systems facing due east or west due to slope shading effect. The results are useful for solar energy collection on nonflat terrains.

NASA Astrophysics Data System (ADS)
Shan, W.; Guo, Y.
20090401
In recent years, in the seasonal frozen regions of Northeast China, the construction of highway improved enormously people's journey condition, but also brought a series of environmental question. In order to meet the route requirement, it is inevitable to excavate the mountain slope, which damage the surface vegetation and cut off the runoff passage of groundwater, cause the outcrop of underground water on the cutting slope and affecte the intrinsic ground stress equilibrium of the slope body, lead to the redistribution of ground stress and the heat balance change in nearsurface of the cutting slope. Under influence of rainfall in autumn and the cold climate in winter, the moisture transfer to frozen zone of cutting slope and lead to the frost heave in shallow depth of the slope. During the thawing period in spring, with effect of integrated factors including rainfall and increasing temperature, ice kernels both on the surface and near the surface of cut slope thaw quickly. The water melting from frozen soil, will hampered by frozen layer in process of infiltration. As a result, the water content of the intersection between the freezing and melting layer is high enough to be saturation or even oversaturation, and accordingly cause the intrinsic effective stress on the slope body decreased. Under the function of gravity, nearsurface slope collapses partially or entirely. As experience of highway construction accumulated, and the consciousness of environmental protection strengthen, the efficiency and the rationality of plant protection slope was realized gradually, slope protection method has transited gradually from masonry body to combined with plant protection, or complete plant protection. Adopted the method combined field test and lab test, this article analyzed the effect of plant system on the temperature and moisture of soil body, especially the rootsoil system in freezing process. The results showed that compared with non plant, the soil body protected
 «
 12
 13
 14
 15
 16
 »
 «
 13
 14
 15
 16
 17
 »

Stability analysis of nonlinear systems with slope restricted nonlinearities.
Liu, Xian; Du, Jiajia; Gao, Qing
20140101
The problem of absolute stability of Lur'e systems with sector and slope restricted nonlinearities is revisited. Novel timedomain and frequencydomain criteria are established by using the Lyapunov method and the wellknown KalmanYakubovichPopov (KYP) lemma. The criteria strengthen some existing results. Simulations are given to illustrate the efficiency of the results.

MultiScale Measures of Rugosity, Slope and Aspect from Benthic Stereo Image Reconstructions
Friedman, Ariell; Pizarro, Oscar; Williams, Stefan B.; JohnsonRoberson, Matthew
20120101
This paper demonstrates how multiscale measures of rugosity, slope and aspect can be derived from finescale bathymetric reconstructions created from georeferenced stereo imagery. We generate threedimensional reconstructions over large spatial scales using data collected by Autonomous Underwater Vehicles (AUVs), Remotely Operated Vehicles (ROVs), manned submersibles and diverheld imaging systems. We propose a new method for calculating rugosity in a Delaunay triangulated surface mesh by projecting areas onto the plane of best fit using Principal Component Analysis (PCA). Slope and aspect can be calculated with very little extra effort, and fitting a plane serves to decouple rugosity from slope. We compare the results of the virtual terrain complexity calculations with experimental results using conventional insitu measurement methods. We show that performing calculations over a digital terrain reconstruction is more flexible, robust and easily repeatable. In addition, the method is noncontact and provides much less environmental impact compared to traditional survey techniques. For diverbased surveys, the time underwater needed to collect rugosity data is significantly reduced and, being a technique based on images, it is possible to use robotic platforms that can operate beyond diver depths. Measurements can be calculated exhaustively at multiple scales for surveys with tens of thousands of images covering thousands of square metres. The technique is demonstrated on data gathered by a diverrig and an AUV, on small singletransect surveys and on a larger, dense survey that covers over . Stereo images provide 3D structure as well as visual appearance, which could potentially feed into automated classification techniques. Our multiscale rugosity, slope and aspect measures have already been adopted in a number of marine science studies. This paper presents a detailed description of the method and thoroughly validates it against traditional in

NASA Astrophysics Data System (ADS)
Senderak, K.; Kondracka, M.; Gądek, B.
20171201
Talus slopes are present in all geographical altitudes, but the most active and dynamic slopes occur in highmountain and polar areas. Spitsbergen, Norwegian archipelago in the Arctic, combines these two environments, therefore, the talus slopes develop in specific environmental conditions that have changed since the beginning of deglaciation. On Spitsbergen, which is 60% glaciated, talus slope evolution depends frequently on the interaction with glaciers, as well as the size of sediment supply area, the lithology, and the intensive of rock weathering. The warming of climate in the Arctic cause the identifiable changes in the internal structures of talus slopes associated with i.e. the melting of glaciers and the high activity of many morphogenetic processes on slope surface. The identification of these changes is a key to understanding of climate change influence (direct and indirect influence) on talus slope evolution. Our work presents the results of research, mainly based on the measurements using electrical resistivity tomography method (ERT) and groundpenetrating radar method (GPR), which were made on the talus slopes of southern Spitsbergen in the vicinity of Polish Polar Station in Hornsund. The geophysical surveys and geomorphological observations show that the climatic factor plays the significant role in the development of slopes, what is clearly visible when analyzing the whole slope systems in the selected glacial valleys (partly glaciated). The differences in the internal structure can depend on distance from the glacier and age of form. This mainly concerns the volume of buried glacial ice in slope material, the thickness of talus slopes, the depth of permafrost and active layer, the stored sedimentological structures including e.g. the traces of fresh material supply. New data on the internal structure of talus slopes developing in the present glaciated area allow for discussions on the talus slope evolution, which, according to the authors, needs

Wavefront analysis from its slope data
NASA Astrophysics Data System (ADS)
Mahajan, Virendra N.; Acosta, Eva
20170801
In the aberration analysis of a wavefront over a certain domain, the polynomials that are orthogonal over and represent balanced wave aberrations for this domain are used. For example, Zernike circle polynomials are used for the analysis of a circular wavefront. Similarly, the annular polynomials are used to analyze the annular wavefronts for systems with annular pupils, as in a rotationally symmetric twomirror system, such as the Hubble space telescope. However, when the data available for analysis are the slopes of a wavefront, as, for example, in a Shack Hartmann sensor, we can integrate the slope data to obtain the wavefront data, and then use the orthogonal polynomials to obtain the aberration coefficients. An alternative is to find vector functions that are orthogonal to the gradients of the wavefront polynomials, and obtain the aberration coefficients directly as the inner products of these functions with the slope data. In this paper, we show that an infinite number of vector functions can be obtained in this manner. We show further that the vector functions that are irrotational are unique and propagate minimum uncorrelated additive random noise from the slope data to the aberration coefficients.

An exact solution for ideal dambreak floods on steep slopes
Ancey, C.; Iverson, R.M.; Rentschler, M.; Denlinger, R.P.
20080101
The shallowwater equations are used to model the flow resulting from the sudden release of a finite volume of frictionless, incompressible fluid down a uniform slope of arbitrary inclination. The hodograph transformation and Riemann's method make it possible to transform the governing equations into a linear system and then deduce an exact analytical solution expressed in terms of readily evaluated integrals. Although the solution treats an idealized case never strictly realized in nature, it is uniquely wellsuited for testing the robustness and accuracy of numerical models used to model shallowwater flows on steep slopes. Copyright 2008 by the American Geophysical Union.

NASA Astrophysics Data System (ADS)
Hill, Kimberly M.; Gaffney, John; Baumgardner, Sarah; Wilco*ck, Peter; Paola, Chris
20170101
When fine sediment is added to a coarsegrained system, the mobility and composition of the bed can change dramatically. We conducted a series of flume experiments to determine how the size of fine particles introduced to an active gravel bed influences the mobility and composition of the bed. We initiated our experiments using a constant water discharge and feed rate of gravel. After the system reached steady state, we doubled the feed rate by supplying a second sediment of equal or lesser size, creating size ratios from 1:1 to 1:150. As we decreased the relative size of the fine particles, the system transitioned among three regimes: (1) For particle size ratios close to one, the bed slope increased to transport the additional load of similarsized particles. The bed surface remained planar and unchanged. (2) For intermediate particle size ratios, the bed slope decreased with the additional fines. The bed surface became patchy with regions of fine and coarse grains. (3) For the largest particle size ratios (the smallest fines), the bed slope remained relatively unchanged. The subsurface became clogged with fine sediment, but fine particles were not present in the surface layer. This third regime constitutes washload, defined by those fractions that do not affect bedmaterial transport conditions. Our results indicate washload should be defined in terms of three conditions: small grain size relative to that of the bed material, full suspension based on the Rouse number, and a small rate of fine sediment supply relative to transport capacity.

NASA Astrophysics Data System (ADS)
Wang, Chunxiang; Watanabe, Naoki; Marui, Hideaki
20130401
The hilly slopes of Mt. Medvednica are stretched in the northwestern part of Zagreb City, Croatia, and extend to approximately 180km2. In this area, landslides, e.g. Kostanjek landslide and Črešnjevec landslide, have brought damage to many houses, roads, farmlands, grassland and etc. Therefore, it is necessary to predict the potential landslides and to enhance landslide inventory for hazard mitigation and security management of local society in this area. We combined deterministic method and probabilistic method to assess potential landslides including their locations, size and sliding surfaces. Firstly, this study area is divided into several slope units that have similar topographic and geological characteristics using the hydrology analysis tool in ArcGIS. Then, a GISbased modified threedimensional Hovland's method for slope stability analysis system is developed to identify the sliding surface and corresponding threedimensional safety factor for each slope unit. Each sliding surface is assumed to be the lower part of each ellipsoid. The direction of inclination of the ellipsoid is considered to be the same as the main dip direction of the slope unit. The center point of the ellipsoid is randomly set to the center point of a grid cell in the slope unit. The minimum threedimensional safety factor and corresponding critical sliding surface are also obtained for each slope unit. Thirdly, since a single value of safety factor is insufficient to evaluate the slope stability of a slope unit, the ratio of the number of calculation cases in which the threedimensional safety factor values less than 1.0 to the total number of trial calculation is defined as the failure probability of the slope unit. If the failure probability is more than 80%, the slope unit is distinguished as 'unstable' from other slope units and the landslide hazard can be mapped for the whole study area.

NASA Astrophysics Data System (ADS)
Darwish, Hany W.; Hassan, Said A.; Salem, Maissa Y.; ElZeiny, Badr A.
20111201
Three simple, specific, accurate and precise spectrophotometric methods manipulating ratio spectra are developed for the simultaneous determination of Amlodipine besylate (AM) and Atorvastatin calcium (AT) in tablet dosage forms. The first method is first derivative of the ratio spectra ( 1DD), the second is ratio subtraction and the third is the method of mean centering of ratio spectra. The calibration curve is linear over the concentration range of 340 and 832 μg/ml for AM and AT, respectively. These methods are tested by analyzing synthetic mixtures of the above drugs and they are applied to commercial pharmaceutical preparation of the subjected drugs. Standard deviation is <1.5 in the assay of raw materials and tablets. Methods are validated as per ICH guidelines and accuracy, precision, repeatability and robustness are found to be within the acceptable limit.

Moul, Judd W; Lilja, Hans; Semmes, O John; Lance, Raymond S; Vessella, Robert L; Fleisher, Martin; Mazzola, Clarisse; Sarno, Mark J; Stevens, Barbara; Klem, Robert E; McDermed, Jonathan E; Triebell, Melissa T; Adams, Thomas H
20121201
To validate the hypothesis that men displaying serum prostatespecific antigen (PSA) slopes ≤ 2.0 pg/mL/mo after prostatectomy, measured using a new immunopolymerase chain reaction diagnostic test (NADiA ProsVue), have a reduced risk of clinical recurrence as determined by positive biopsy, imaging findings, or death from prostate cancer. From 4 clinical sites, we selected a cohort of 304 men who had been followed up for 17.6 years after prostatectomy for clinical recurrence. We assessed the prognostic value of a PSA slope cutpoint of 2.0 pg/mL/mo against established risk factors to identify men at low risk of clinical recurrence using uni and multivariate Cox proportional hazards regression and KaplanMeier analyses. The univariate hazard ratio of a PSA slope >2.0 pg/mL/mo was 18.3 (95% confidence interval 10.631.8) compared with a slope ≤ 2.0 pg/mL/mo (P <.0001). The median diseasefree survival interval was 4.8 years vs >10 years in the 2 groups (P <.0001). The multivariate hazard ratio for PSA slope with the covariates of preprostatectomy PSA, pathologic stage, and Gleason score was 9.8 (95% confidence interval 5.417.8), an 89.8% risk reduction for men with PSA slopes ≤ 2.0 pg/mL/mo (P <.0001). The Gleason score (<7 vs ≥ 7) was the only other significant predictor (hazard ratio 5.4, 95% confidence interval 2.113.8, P = .0004). Clinical recurrence after radical prostatectomy is difficult to predict using established risk factors. We have demonstrated that a NADiA ProsVue PSA slope of ≤ 2.0 pg/mL/mo after prostatectomy is prognostic for a reduced risk of prostate cancer recurrence and adds predictive power to the established risk factors. Copyright © 2012 Elsevier Inc. All rights reserved.

NASA Astrophysics Data System (ADS)
DeNiro, Michael J.; Sternberg, Leonel D.; Marino, Bruno D.; Druzik, James R.
19880901
The 18O /16O ratios of cellulose and the D/H ratios of cellulose nitrate were determined for linen, a textile produced from the fibers of the flax plant Linum usitatissimum, and for maize ( Zea mays) from a variety of geographic locations in Europe, the Middle East, and North and South America. The regression lines of δD values on δ 18O values had slopes of 5.4 and 5.8 for the two species. Statistical analysis of results reported in the only other study in which samples of a single species (the silver fir Abies pindrow) that grew under a variety of climatic conditions were analyzed yielded slopes of ~6 when δD values of cellulose nitrate were regressed on δ 18O values of cellulose. The occurrence of this previously unrecognized relationship in three species suggests it may obtain in other plants as well. Determining the basis for this relationship, which is not possible given current understanding of fractionation of the isotopes of oxygen and hydrogen by plants, should lead to increased understanding of how D/H and 18O /16O ratios in cellulose isolated from fossil plants are related to paleoclimates. The separation of most linen samples from Europe from those originating in the Middle East when δD values are plotted against δ 18O values suggests it may be possible to use the isotope ratios of cellulose prepared from the Shroud of Turin to resolve the controversy concerning its geographic origin.

Numerical study of dambreak induced tsunamilike bore with a hump of different slopes
NASA Astrophysics Data System (ADS)
Cheng, Du; Zhao, Xizeng; Zhang, Dake; Chen, Yong
20171201
Numerical simulation of dambreak wave, as an imitation of tsunami hydraulic bore, with a hump of different slopes is performed in this paper using an inhouse code, named a Constrained Interpolation Profile (CIP)based model. The model is built on a Cartesian grid system with the Navier Stokes equations using a CIP method for the flow solver, and employs an immersed boundary method (IBM) for the treatment of solid body boundary. A more accurate interface capturing scheme, the Tangent of hyperbola for interface capturing/Slope weighting (THINC/SW) scheme, is adopted as the interface capturing method. Then, the CIPbased model is applied to simulate the dam break flow problem in a bumpy channel. Considerable attention is paid to the spilling type reflected bore, the following spilling type wave breaking, free surface profiles and water level variations over time. Computations are compared with available experimental data and other numerical results quantitatively and qualitatively. Further investigation is conducted to analyze the influence of variable slopes on the flow features of the tsunamilike bore.

Reinforcing mechanism of anchors in slopes: a numerical comparison of results of LEM and FEM
NASA Astrophysics Data System (ADS)
Cai, Fei; Ugai, Keizo
20030601
This paper reports the limitation of the conventional Bishop's simplified method to calculate the safety factor of slopes stabilized with anchors, and proposes a new approach to considering the reinforcing effect of anchors on the safety factor. The reinforcing effect of anchors can be explained using an additional shearing resistance on the slip surface. A threedimensional shear strength reduction finite element method (SSRFEM), where soilanchor interactions were simulated by threedimensional zerothickness elastoplastic interface elements, was used to calculate the safety factor of slopes stabilized with anchors to verify the reinforcing mechanism of anchors. The results of SSRFEM were compared with those of the conventional and proposed approaches for Bishop's simplified method for various orientations, positions, and spacings of anchors, and shear strengths of soilgrouted body interfaces. For the safety factor, the proposed approach compared better with SSRFEM than the conventional approach. The additional shearing resistance can explain the influence of the orientation, position, and spacing of anchors, and the shear strength of soilgrouted body interfaces on the safety factor of slopes stabilized with anchors.

Development of a GISbased failure investigation system for highway soil slopes
NASA Astrophysics Data System (ADS)
Ramanathan, Raghav; Aydilek, Ahmet H.; Tanyu, Burak F.
20150601
A framework for preparation of an early warning system was developed for Maryland, using a GIS database and a collective overlay of maps that highlight highway slopes susceptible to soil slides or slope failures in advance through spatial and statistical analysis. Data for existing soil slope failures was collected from geotechnical reports and field visits. A total of 48 slope failures were recorded and analyzed. Six factors, including event precipitation, geological formation, land cover, slope history, slope angle, and elevation were considered to affect highway soil slope stability. The observed trends indicate that precipitation and poor surface or subsurface drainage conditions are principal factors causing slope failures. 96% of the failed slopes have an open drainage section. A majority of the failed slopes lie in regions with relatively high event precipitation ( P>200 mm). 90% of the existing failures are surficial erosion type failures, and only 1 out of the 42 slope failures is deep rotational type failure. More than half of the analyzed slope failures have occurred in regions having low density land cover. 46% of failures are on slopes with slope angles between 20° and 30°. Influx of more data relating to failed slopes should give rise to more trends, and thus the developed slope management system will aid the state highway engineers in prudential budget allocation and prioritizing different remediation projects based on the literature reviewed on the principles, concepts, techniques, and methodology for slope instability evaluation (Leshchinsky et al., 2015).

Snow and Frost Depths on North and South Slopes
Richard S. Sartz
19730101
Aspect affects soil frost depth by influencing the amount of solar radiation received at the ground or snow surface. Depending on the conditions, frost can be of equal depth on north and south slopes, deeper on north slopes, or deeper on south slopes. Data illustrate all three conditions

NASA Astrophysics Data System (ADS)
Gusman, M.; Nazki, A.; Putra, R. R.
20180401
One of the parameters in slope stability analysis is the shear strength of the soil. Changes in soil shear strength characteristics lead to a decrease in safety factors on the slopes. This study aims to see the effect of increased moisture content on soil mechanical parameters. The case study study was conducted on the slopes of Sitinjau Lauik Kota Padang. The research method was done by laboratory analysis and simple liniear regression analysis and multiple. Based on the test soil results show that the increase in soil water content causes a decrease in cohesion values and internal shear angle. The relationship of moisture content to cohesion is described in equation Y = 55.7130,6X with R2 = 0.842. While the relationship of water content to shear angle in soil is described in the equation Y = 38.8780.258X with R2 = 0.915. From several simulations of soil water level improvement, calculation of safety factor (SF) of slope. The calculation results show that the increase of groundwater content is very significant affect the safety factor (SF) slope. SF slope values are in safe condition when moisture content is 50% and when it reaches maximum water content 73.74% slope safety factor value potentially for landslide.

NASA Astrophysics Data System (ADS)
Vulliez, Cindy; Guerin, Antoine; Abellán, Antonio; Derron, MarcHenri; Jaboyedoff, Michel; Chanut, MarieAurélie; Dubois, Laurent; Duranthon, JeanPaul
20160401
The Séchilienne landslide located in the Romanche Valley (Isère, France) is a well instrumented mass movements of about 650 m high and 250 m wide, with a potential volume of about 3 million m3 in the most active part (Duranthon and Effendiantz, 2004 ; Kasperski et al., 2010). The slope, which is mainly composed of micaschist, is characterized by the presence of a NESW subvertical fracturing system involved in the destabilization of the area. The rock slope has been continuously moving since the eighties decade, with a growing acceleration during the period 20092013 followed by a progressive stabilization during the last years. The monitoring of the active part of the rock slide is currently carried out by an instrumentation system in order to prevent a large failure. In this work, we used different 3D techniques in order to monitor the whole rock slide displacements in three dimensions, as follows: (a) First of all, we used a Terrestrial Laser Scanning to obtain high resolution point clouds (8 cm point spacing) of the rock slope geometry. Nine different fieldwork campaigns were performed during the last six years, as follows: Aug. 2009, Jul. 2010, Nov. 2011, Nov. 2012, Jun. and Nov. 2013, Jul. and Oct. 2014, May 2015, which provided a set of 3D representations of the rock slope topography over time; (b) In addition, we used three Helicopterbased Laser Scanning campaigns carried out in Jan. 2011, Feb. 2012 and Mar. 2014 acquired by the Cerema (Chanut et al., 2014); (c) Finally, more than 600 photos were taken in Apr. 2015 in order to build a photogrammetric model of the area using StructurefromMotion (SfM) workflow in Agisoft PhotoScan software. All types of data were complementary for the study of the movement and allowed us having a good spatial vision of the evolution of the most active part of the slope. A detailed structural analysis was performed from both LiDAR and SfM point clouds using Coltop3D (Jaboyedoff et al., 2007). Eight joint sets were

NASA Astrophysics Data System (ADS)
Cheng, Yayun; Qi, Bo; Liu, Siyuan; Hu, Fei; Gui, Liangqi; Peng, Xiaohui
20161001
Polarimetric measurements can provide additional information as compared to unpolarized ones. In this paper, linear polarization ratio (LPR) is created to be a feature discriminator. The LPR properties of several materials are investigated using Fresnel theory. The theoretical results show that LPR is sensitive to the material type (metal or dielectric). Then a linear polarization ratiobased (LPRbased) method is presented to distinguish between metal and dielectric materials. In order to apply this method to practical applications, the optimal range of incident angle have been discussed. The typical outdoor experiments including various objects such as aluminum plate, grass, concrete, soil and wood, have been conducted to validate the presented classification method.

Hill slope and erosional controls on soil organic geochemistry in intensely managed landscapes
NASA Astrophysics Data System (ADS)
Filley, T. R.; Hou, T.; Hughes, M.; Tong, Y.; Papanicolaou, T.; Wacha, K.; Abban, B. K.; Boys, J.; Wilson, C. G.
20151201
Like many regions of North America, the last 100 years of agriculture in the glaciated upper Midwest has lead to a major redistribution of soil carbon and nitrogen on the landscape. Through the natural coevolution of geomorphic, pedogenic, and ecological processes in the critical zone or by punctual changes in these processes as a result of intensive management, landscapes established characteristic hierarchies of physicochemical controls on organic matter stability. In the IntensivelyManaged Landscapes  Critical Zone Observatory (IMLCZO) in Iowa and Illinois these processes are being studied with a combination of surface soil geochemical surveys and simulated rainfall/erosion experiments to document how the organic geochemistry of hill slopes, under land management ranging from row crop to restored prairie, are currently evolving, and how they evolved during early management and pre settlement. Using a combination of soil analyses including elemental, stable isotope, textural, and soil biopolymers (lignin and cutin/suberin fatty acids (SFA)) we investigated the spatial patterns of static surface soil properties and time course rainfallerosional experiments along the same slopes to gain insight into soil carbon and biopolymer enrichment patterns in eastcentral Iowa within the Clear Creek Watershed. Both lignin and substituted fatty acid concentration and their molecular ratios highlighted differences in C3/C4 (soy/corn) management activities in surface soils while over 40 years of prairie restoration dramatically altered surface soil profiles. For example, a general pattern in static baseline samples was an enrichment of 15N in soils down slope and an opposite pattern of accumulation/loss of lignin and SFA in topographic highs and lows. Transport of soil particles, associated biopolymers, and elemental and isotope signatures, exhibited distinct patterns based upon both position of the hill slope and directionality of flow with respect to rill/gully direction

Innovative techniques with multipurpose survey vehicle for automated analysis of crossslope data.
DOT National Transportation Integrated Search
20071102
Manual surveying methods have long been used in the field of highway engineering to determine : the crossslope, and longitudinal grade of an existing roadway. However, these methods are : slow, tedious and labor intensive. Moreover, manual survey me...

Reorienting with terrain slope and landmarks.
Nardi, Daniele; Newcombe, Nora S; Shipley, Thomas F
20130201
Orientation (or reorientation) is the first step in navigation, because establishing a spatial frame of reference is essential for a sense of location and heading direction. Recent research on nonhuman animals has revealed that the vertical component of an environment provides an important source of spatial information, in both terrestrial and aquatic settings. Nonetheless, humans show large individual and sex differences in the ability to use terrain slope for reorientation. To understand why some participantsmainly womenexhibit a difficulty with slope, we tested reorientation in a richer environment than had been used previously, including both a tilted floor and a set of distinct objects that could be used as landmarks. This environment allowed for the use of two different strategies for solving the task, one based on directional cues (slope gradient) and one based on positional cues (landmarks). Overall, rather than using both cues, participants tended to focus on just one. Although men and women did not differ significantly in their encoding of or reliance on the two strategies, men showed greater confidence in solving the reorientation task. These facts suggest that one possible cause of the female difficulty with slope might be a generally lower spatial confidence during reorientation.
 «
 13
 14
 15
 16
 17
 »
 «
 14
 15
 16
 17
 18
 »

NASA Astrophysics Data System (ADS)
Gallegos, M. I.; EspejelGarcia, V. V.
20121201
The Camargo volcanic field (CVF) covers ~3000 km2 and is located in the southeast part of the state of Chihuahua, within the Basin and Range province. The CVF represents the largest mafic alkali volcanic field in northern Mexico. Over a 300 cinder cones have been recognized in the Camargo volcanic field. Volcanic activity ranges from 4.7 to 0.09 Ma revealed by 40Ar/39Ar dating methods. Previous studies say that there is a close relationship between the cinder cone slope angle, due to mechanical weathering, and age. This technique is considered a reliable age indicator, especially in arid climates, such as occur in the CVF. Data were acquired with digital topographic maps (DRG) and digital elevation models (DEM) overlapped in the Global Mapper software. For each cone, the average radius (r) was calculated from six measurements, the height (h) is the difference between peak elevation and the altitude of the contour used to close the radius, and the slope angle was calculated using the equation Θ = tan1(h/r). The slope angles of 30 cinder cones were calculated showing angles ranging from 4 to 15 degrees. A diffusion model, displayed by an exponential relationship between slope angle and age, places the ages of these 30 cones from 215 to 82 ka, within the range marked by radiometric methods. Future work include the analysis of more cinder cones to cover the whole CVF, and contribute to the validation of this technique.

Gravitydriven groundwater flow and slope failure potential: 1. Elastic effectivestress model
Iverson, Richard M.; Reid, Mark E.
19920101
Hilly or mountainous topography influences gravitydriven groundwater flow and the consequent distribution of effective stress in shallow subsurface environments. Effective stress, in turn, influences the potential for slope failure. To evaluate these influences, we formulate a twodimensional, steady state, poroelastic model. The governing equations incorporate groundwater effects as body forces, and they demonstrate that spatially uniform pore pressure changes do not influence effective stresses. We implement the model using two finite element codes. As an illustrative case, we calculate the groundwater flow field, total body force field, and effective stress field in a straight, hom*ogeneous hillslope. The total body force and effective stress fields show that groundwater flow can influence shear stresses as well as effective normal stresses. In most parts of the hillslope, groundwater flow significantly increases the Coulomb failure potential Φ, which we define as the ratio of maximum shear stress to mean effective normal stress. Groundwater flow also shifts the locus of greatest failure potential toward the slope toe. However, the effects of groundwater flow on failure potential are less pronounced than might be anticipated on the basis of a simpler, onedimensional, limit equilibrium analysis. This is a consequence of continuity, compatibility, and boundary constraints on the twodimensional flow and stress fields, and it points to important differences between our elastic continuum model and limit equilibrium models commonly used to assess slope stability.

Seasonal flows on warm Martian slopes
McEwen, A.S.; Ojha, L.; Dundas, C.M.; Mattson, S.S.; Byrne, S.; Wray, J.J.; Cull, S.C.; Murchie, S.L.; Thomas, N.; Gulick, V.C.
20110101
Water probably flowed across ancient Mars, but whether it ever exists as a liquid on the surface today remains debatable. Recurring slope lineae (RSL) are narrow (0.5 to 5 meters), relatively dark markings on steep (25?? to 40??) slopes; repeat images from the Mars Reconnaissance Orbiter High Resolution Imaging Science Experiment show them to appear and incrementally grow during warm seasons and fade in cold seasons. They extend downslope from bedrock outcrops, often associated with small channels, and hundreds of them form in some rare locations. RSL appear and lengthen in the late southern spring and summer from 48??S to 32??S latitudes favoring equatorfacing slopes, which are times and places with peak surface temperatures from ???250 to 300 kelvin. Liquid brines near the surface might explain this activity, but the exact mechanism and source of water are not understood.

NASA Astrophysics Data System (ADS)
Xiao, Lili; Chai, Bo; Yin, Kunlong
20150901
A passenger elevator is to be built on a nearly vertical slope in the National Geological Park in Enshi, Hubei province, China. Three steps comprise the construction: excavating the slope toe for the elevator platform, building the elevator on the platform, and affixing the elevator to the slope using anchors. To evaluate the rock slope stability in the elevator area and the safety of the elevator construction, we applied three techniques: qualitative analysis, formula calculation, and numerical simulation methods, based on field investigation and parameter selection, and considering both wet and dry conditions, pre and postconstruction. Qualitative stability factors for sliding and falling were calculated using the limit equilibrium method; the results show that the slope as a whole is stable, with a few unstable blocks, notably block BT1. Formulabased stability factors were calculated for four sections on block BT1, revealing the following: anchors will decrease the stability of certain rock pieces; the lowest average stability factor after anchoring will be K f = 1.36 in wet conditions; block BT1 should be reinforced during elevator construction, up to a firstclass slope stability factor of K f = 1.40; and the slope as a whole is stable. Numerical simulation using FLAC3D indicated that the stress distribution will reach equilibrium for all steps before and after construction, and that the factor of safety (FOS) is within the general slope safety range (FOS > 1.05). We suggest that unstable pieces in block BT1 be reinforced during construction to a firstclass slope safety range (FOS > 1.3), and that deformation monitoring on the slope surface be implemented.

ERIC Educational Resources Information Center
Patel, Rita Manubhai
20130101
This dissertation examined understanding of slope and derivative concepts and mathematical dispositions of firstsemester college calculus students, who are recent high school graduates, transitioning to university mathematics. The present investigation extends existing research in the following ways. First, based on this investigation, the…

Davis, G.H.
19610101
Chemical analyses of waters of streams that drain the semiarid eastern slope of the southern Coast Ranges in California demonstrate that differences in the anion composition, especially in the ratio of bicarbonate to sulfate, are related chiefly to the lithologic character of the rocks exposed in the tributary drainage area. Where more than hall the drainage area of a typical easternslope stream is underlain by clastic marine sedimentary rocks of Jurassic and Cretaceous age, bicarbonate generally predominates over sulfate; the ratio of bicarbonate to sullate, both expressed in equivalents per million, in samples of the streams at lowflow stage ranges from 0.8 to 6. Conversely, where more than hall the drainage area is underlain by marine and continental deposits of Tertiary age and continental deposits of Quaternary age, sulfate predominates over bicarbonate, and the ratio of bicarbonate to sulfate in samples taken during the lowflow stage ranges from 0.02 to 0.7. Organic siliceous marine shale of Tertiary age deposited in a reducing environment is probably the primary source of sullate in the region. Secondary deposits of sulfate minerals, chiefly gypsum, which are abundant in the continental deposits of late Tertiary and Quaternary age, also contribute sullate to the stream waters.

Sediment Pathways Across Trench Slopes: Results From Numerical Modeling
NASA Astrophysics Data System (ADS)
Cormier, M. H.; Seeber, L.; McHugh, C. M.; Fujiwara, T.; Kanamatsu, T.; King, J. W.
20151201
Until the 2011 Mw9.0 Tohoku earthquake, the role of earthquakes as agents of sediment dispersal and deposition at erosional trenches was largely underappreciated. A series of cruises carried out after the 2011 event has revealed a variety of unsuspected sediment transport mechanisms, such as tsunamitriggered sheet turbidites, suggesting that great earthquakes may in fact be important agents for dispersing sediments across trench slopes. To complement these observational data, we have modeled the pathways of sediments across the trench slope based on bathymetric grids. Our approach assumes that transport direction is controlled by slope azimuth only, and ignores obstacles smaller than 0.61 km; these constraints are meant to approximate the behavior of turbidites. Results indicate that (1) most pathways issued from the upper slope terminate near the top of the small frontal wedge, and thus do not reach the trench axis; (2) in turn, sediments transported to the trench axis are likely derived from the small frontal wedge or from the subducting Pacific plate. These results are consistent with the stratigraphy imaged in seismic profiles, which reveals that the slope apron does not extend as far as the frontal wedge, and that the thickness of sediments at the trench axis is similar to that of the incoming Pacific plate. We further applied this modeling technique to the Cascadia, Nankai, MiddleAmerica, and Sumatra trenches. Where welldefined canyons carve the trench slopes, sediments from the upper slope may routinely reach the trench axis (e.g., off Costa Rica and Cascadia). In turn, slope basins that are isolated from the canyons drainage systems must mainly accumulate locallyderived sediments. Therefore, their turbiditic infill may be diagnostic of seismic activity only  and not from storm or flood activity. If correct, this would make isolated slope basins ideal targets for paleoseismological investigation.

Distribution of Lepidopteran Larvae on Norway Spruce: Effects of Slope and Crown Aspect.
Kulfan, Ján; Dvořáčková, Katarína; Zach, Peter; Parák, Michal; Svitok, Marek
20160401
Lepidoptera associated with Norway spruce, Picea abies (L.) Karsten, play important roles in ecosystem processes, acting as plant pests, prey for predators, and hosts for parasites and parasitoids. Their distribution patterns in spruce crowns and forests are only poorly understood. We examined how slope and crown aspect affect the occurrence and abundance of moth larvae on solitary spruce trees in a montane region in Central Europe. Moth larvae were collected from southern and northern crowns of trees growing on south and northfacing slopes (four treatments) using emergence boxes at the end of winter and by the beating method during the growing season. Species responses to slope and crown aspect were not uniform. Treatment effects on moth larvae were stronger in the winter than during the growing season. In winter, the abundance of budboring larvae was significantly higher in northern than in southern crowns regardless of the slope aspect, while both slope and aspect had marginally significant effects on abundance of miners. During the growing season, the occurrence of freeliving larvae was similar among treatments. Emergence boxes and beating spruce branches are complementary techniques providing valuable insights into the assemblage structure of moth larvae on Norway spruce. Due to the uneven distribution of larvae detected in this study, we recommend adoption of a protocol that explicitly includes sampling of trees from contrasting slopes and branches from contrasting crown aspect in all seasons. © The Authors 2016. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Threedimensional modelling of slope stability using the Local Factor of Safety concept
NASA Astrophysics Data System (ADS)
Moradi, Shirin; Huisman, Sander; Beck, Martin; Vereecken, Harry; Class, Holger
20170401
Slope stability is governed by coupled hydrological and mechanical processes. The slope stability depends on the effective stress, which in turn depends on the weight of the soil and the matrix potential. Therefore, changes in water content and matrix potential associated with infiltration will affect slope stability. Most available models describing these coupled hydromechanical processes either rely on a one or twodimensional representation of hydrological and mechanical properties and processes, which obviously is a strong simplification in many applications. Therefore, the aim of this work is to develop a threedimensional hydromechanical model that is able to capture the effect of spatial and temporal variability of both mechanical and hydrological parameters on slope stability. For this, we rely on DuMux, which is a free and opensource simulator for flow and transport processes in porous media that facilitates coupling of different model approaches and offers flexibility for model development. We use the Richards equation to model unsaturated water flow. The simulated water content and matrix potential distribution is used to calculate the effective stress. We only consider linear elasticity and solve for statically admissible fields of stress and displacement without invoking failure or the redistribution of postfailure stress or displacement. The Local Factor of Safety concept is used to evaluate slope stability in order to overcome some of the main limitations of commonly used methods based on limit equilibrium considerations. In a first step, we compared our model implementation with a 2D benchmark model that was implemented in COMSOL Multiphysics. In a second step, we present insilico experiments with the newly developed 3D model to show the effect of slope morphology, spatial variability in hydraulic and mechanical material properties, and spatially variable soil depth on simulated slope stability. It is expected that this improved physically

The world is not flat: can people reorient using slope?
Nardi, Daniele; Newcombe, Nora S; Shipley, Thomas F
20110301
Studies of spatial representation generally focus on flat environments and visual input. However, the world is not flat, and slopes are part of most natural environments. In a series of 4 experiments, we examined whether humans can use a slope as a source of allocentric, directional information for reorientation. A target was hidden in a corner of a square, featureless enclosure tilted at a 5° angle. Finding it required using the vestibular, kinesthetic, and visual cues associated with the slope gradient. In Experiment 1, the overall sample performed above chance, showing that slope is sufficient for reorientation in a real environment. However, a sex difference emerged; men outperformed women by 1.4 SDs because they were more likely to use a slopebased strategy. In Experiment 2, attention was drawn to the slope, and participants were prompted to rely on it to solve the task; however, men still outperformed women, indicating a greater ability to use slope. In Experiment 3, we excluded the possibility that women's disadvantage was due to wearing heeled footwear. In Experiment 4, women required more time than men to identify the uphill direction of the slope gradient; this suggests that, in a bottomup fashion, a perceptual or attentional difficulty underlies women's disadvantage in the ability to use slope and their decreased reliance on this cue. Overall, a bicoordinate representation was used to find the goal: The target was encoded primarily with respect to the vertical axis and secondarily with respect to the orthogonal axis of the slope. 2011 APA, all rights reserved

Role of slope on infiltration: A review
NASA Astrophysics Data System (ADS)
Morbidelli, Renato; Saltalippi, Carla; Flammini, Alessia; Govindaraju, Rao S.
20180201
Partitioning of rainfall at the soilatmosphere interface is important for both surface and subsurface hydrology, and influences many events of major hydrologic interest such as runoff generation, aquifer recharge, and transport of pollutants in surface waters as well as the vadose zone. This partitioning is achieved through the process of infiltration that has been widely investigated at the local scale, and more recently also at the field scale, by models that were designed for horizontal surfaces. However, infiltration, overland flows, and deep flows in most real situations are generated by rainfall over sloping surfaces that bring in additional effects. Therefore, existing models for local infiltration into hom*ogeneous and layered soils and those as for fieldscale infiltration, have to be adapted to account for the effects of surface slope. Various studies have investigated the role of surface slope on infiltration based on a theoretical formulations for the dynamics of infiltration, extensions of the GreenAmpt approach, and from laboratory and field experiments. However, conflicting results have been reported in the scientific literature on the role of surface slope on infiltration. We summarize the salient points from previous studies and provide plausible reasons for discrepancies in conclusions of previous authors, thus leading to a critical assessment of the current state of our understanding on this subject. We offer suggestions for future efforts to advance our knowledge of infiltration over sloping surfaces.

Multiple slope failures shaped the lower continental slope offshore NW Svalbard in the Fram Strait
NASA Astrophysics Data System (ADS)
Osti, Giacomo; Mienert, Jürgen; Forwick, Matthias; Sverre Laberg, Jan
20160401
Bathymetry data show that the lower slope (between 1300 m and 3000 m water depth) of the NWSvalbard passive margin has been affected by multiple slope failure events. The single events differ in terms of extension, volume of mobilized sediments, morphology of the slide scar, runout distance and age. As for several megascale and minor Arctic slides, the trigger mechanism is still speculative and may include high sedimentation rates, dissociation of gas hydrates, excess pore pressure, or earthquakes caused by isostatic rebound. In this study, we discuss the potential trigger mechanisms that have led to the multiple slope failure events within what we suggest to be named the Fram Strait Slide Complex. The slide complex lies in proximity to the tectonically active Spitsbergen Fracture Zone where earthquakes events, occurrences of potential weak layers in the sediment column, low sedimentation rates, and extended gas hydratebearing sediments may all have contributed to the causes leading to multiple slope failures. Preliminary results obtained from 14C dating on N. pachyderma sin. from sediment cores from the Spitsbergen Fracture Zone slides (SFZS 1 and 2), coupled with subbottom profiler data (frequency 9 to 15 KHz) show that the two shallowest glide planes within one of the observed slide scars failed ~100,000 and ~115,000 yr BP. Whilst SFZS 1 affected an area of 750 km2 mobilizing a total sediment volume of 40 km3, SFZS 2 moved an area of 230 km2 with a sediment volume of 4.5 km3.

Hydrologic behavior of model slopes with synthetic water repellent soils
NASA Astrophysics Data System (ADS)
Zheng, Shuang; Lourenço, Sérgio D. N.; Cleall, Peter J.; Chui, Ting Fong May; Ng, Angel K. Y.; Millis, Stuart W.
20171101
In the natural environment, soil water repellency decreases infiltration, increases runoff, and increases erosion in slopes. In the built environment, soil water repellency offers the opportunity to develop granular materials with controllable wettability for slope stabilization. In this paper, the influence of soil water repellency on the hydrological response of slopes is investigated. Twentyfour flume tests were carried out in model slopes under artificial rainfall; soils with various wettability levels were tested, including wettable (Contact Angle, CA < 90°), subcritical water repellent (CA ∼ 90°) and water repellent (CA > 90°). Various rainfall intensities (30 mm/h and 70 mm/h), slope angles (20° and 40°) and relative compactions (70% and 90%) were applied to model the response of natural and manmade slopes to rainfall. To quantitatively assess the hydrological response, a number of measurements were made: runoff rate, effective rainfall rate, time to ponding, time to steady state, runoff acceleration, total water storage and wetting front rate. Overall, an increase in soil water repellency reduces infiltration and shortens the time for runoff generation, with the effects amplified for high rainfall intensity. Comparatively, the slope angle and relative compaction had only a minor contribution to the slope hydrology. The subcritical water repellent soils sustained infiltration for longer than both the wettable and water repellent soils, which presents an added advantage if they are to be used in the built environment as barriers. This study revealed substantial impacts of manmade or synthetically induced soil water repellency on the hydrological behavior of model slopes in controlled conditions. The results shed light on our understanding of hydrological processes in environments where the occurrence of natural soil water repellency is likely, such as slopes subjected to wildfires and in agricultural and forested slopes.

Slope Stability Analysis In Seismic Areas Of The Northern Apennines (Italy)
DOE Office of Scientific and Technical Information (OSTI.GOV)
Lo Presti, D.; Fontana, T.; Marchetti, D.
20080708
Several research works have been published on the slope stability in the northern Tuscany (central Italy) and particularly in the seismic areas of Garfa*gnana and Lunigiana (Lucca and MassaCarrara districts), aimed at analysing the slope stability under static and dynamic conditions and mapping the landslide hazard. In addition, in situ and laboratory investigations are available for the study area, thanks to the activities undertaken by the Tuscany Seismic Survey. Based on such a huge information the coseismic stability of few ideal slope profiles have been analysed by means of Limit equilibrium method LEM  (pseudostatic) and Newmark sliding block analysismore» (pseudodynamic). The analysisresults gave indications about the most appropriate seismic coefficient to be used in pseudostatic analysis after establishing allowable permanent displacement. Such indications are commented in the light of the Italian and European prescriptions for seismic stability analysis with pseudostatic approach. The stability conditions, obtained from the previous analyses, could be used to define microzonation criteria for the study area.«less

Slope Stability. CEGS Programs Publication Number 15.
ERIC Educational Resources Information Center
Pestrong, Raymond
Slope Stability is one in a series of singletopic problem modules intended for use in undergraduate and earth science courses. The module, also appropriate for use in undergraduate civil engineering and engineering geology courses, is a selfstanding introduction to studies of slope stability. It has been designed to supplement standard…

The Slope Test: Applications in Formative Evaluation.
ERIC Educational Resources Information Center
Baggaley, Jon; Brauer, AaronHenry
19890101
Discusses problems with formative evaluation of educational materials and examines the slope test when used in a pretest/posttest multiple group (PPMG) design to adjust posttest scores treatment interaction studies. An example is given of the utility of the slope test and analysis of covariance procedure using an educational film about AIDS. (five…

A method for estimating fall adult sex ratios from production and survival data
Wight, H.M.; Heath, R.G.; Geis, A.D.
19650101
This paper presents a method of utilizing data relating to the production and survival of a bird population to estimate a basic fall adult sex ratio. This basic adult sex ratio is an average value derived from average production and survival rates. It is an estimate of the average sex ratio about which the fall adult ratios will fluctuate according to annual variations in production and survival. The basic fall adult sex ratio has been calculated as an asymptotic value which is the limit of an infinite series wherein average population characteristics are used as constants. Graphs are provided that allow the determination of basic sex ratios from production and survival data of a population. Where the respective asymptote has been determined, it may be possible to estimate various production and survival rates by use of variations of the formula for estimating the asymptote.

Invariant Imbedded TMatrix Method for Axial Symmetric Hydrometeors with Extreme Aspect Ratios
NASA Technical Reports Server (NTRS)
Pelissier, Craig; Kuo, KwoSen; Clune, Thomas; Adams, Ian; Munchak, Stephen
20170101
The singlescattering properties (SSPs) of hydrometeors are the fundamental quantities for physicsbased precipitation retrievals. Thus, efficient computation of their electromagnetic scattering is of great value. Whereas the semianalytical TMatrix methods are likely the most efficient for nonspherical hydrometeors with axial symmetry, they are not suitable for arbitrarily shaped hydrometeors absent of any significant symmetry, for which volume integral methods such as those based on Discrete Dipole Approximation (DDA) are required. Currently the two leading Tmatrix methods are the Extended Boundary Condition Method (EBCM) and the Invariant Imbedding Tmatrix Method incorporating LorentzMie Separation of Variables (IITM+SOV). EBCM is known to outperform IITM+SOV for hydrometeors with modest aspect ratios. However, in cases when aspect ratios become extreme, such as needlelike particles with large height to diameter values, EBCM fails to converge. Such hydrometeors with extreme aspect ratios are known to be present in solid precipitation and their SSPs are required to model the radiative responses accurately. In these cases, IITM+SOV is shown to converge. An efficient, parallelized C++ implementation for both EBCM and IITM+SOV has been developed to conduct a performance comparison between EBCM, IITM+SOV, and DDSCAT (a popular implementation of DDA). We present the comparison results and discuss details. Our intent is to release the combined ECBM IITM+SOV software to the community under an open source license.

NASA Astrophysics Data System (ADS)
Brewick, Patrick T.; Smyth, Andrew W.
20161201
The authors have previously shown that many traditional approaches to operational modal analysis (OMA) struggle to properly identify the modal damping ratios for bridges under traffic loading due to the interference caused by the driving frequencies of the traffic loads. This paper presents a novel methodology for modal parameter estimation in OMA that overcomes the problems presented by driving frequencies and significantly improves the damping estimates. This methodology is based on finding the power spectral density (PSD) of a given modal coordinate, and then dividing the modal PSD into separate regions, left and rightside spectra. The modal coordinates were found using a blind source separation (BSS) algorithm and a curvefitting technique was developed that uses optimization to find the modal parameters that best fit each side spectra of the PSD. Specifically, a patternsearch optimization method was combined with a clustering analysis algorithm and together they were employed in a series of stages in order to improve the estimates of the modal damping ratios. This method was used to estimate the damping ratios from a simulated bridge model subjected to moving traffic loads. The results of this method were compared to other established OMA methods, such as Frequency Domain Decomposition (FDD) and BSS methods, and they were found to be more accurate and more reliable, even for modes that had their PSDs distorted or altered by driving frequencies.

Invariant Imbedding TMatrix Method for Axial Symmetric Hydrometeors with Extreme Aspect Ratios
NASA Astrophysics Data System (ADS)
Pelissier, C.; Clune, T.; Kuo, K. S.; Munchak, S. J.; Adams, I. S.
20171201
The singlescattering properties (SSPs) of hydrometeors are the fundamental quantities for physicsbased precipitation retrievals. Thus, efficient computation of their electromagnetic scattering is of great value. Whereas the semianalytical TMatrix methods are likely the most efficient for nonspherical hydrometeors with axial symmetry, they are not suitable for arbitrarily shaped hydrometeors absent of any significant symmetry, for which volume integral methods such as those based on Discrete Dipole Approximation (DDA) are required. Currently the two leading Tmatrix methods are the Extended Boundary Condition Method (EBCM) and the Invariant Imbedding Tmatrix Method incorporating LorentzMie Separation of Variables (IITM+SOV). EBCM is known to outperform IITM+SOV for hydrometeors with modest aspect ratios. However, in cases when aspect ratios become extreme, such as needlelike particles with large height to diameter values, EBCM fails to converge. Such hydrometeors with extreme aspect ratios are known to be present in solid precipitation and their SSPs are required to model the radiative responses accurately. In these cases, IITM+SOV is shown to converge. An efficient, parallelized C++ implementation for both EBCM and IITM+SOV has been developed to conduct a performance comparison between EBCM, IITM+SOV, and DDSCAT (a popular implementation of DDA). We present the comparison results and discuss details. Our intent is to release the combined ECBM & IITM+SOV software to the community under an open source license.
 «
 14
 15
 16
 17
 18
 »
 «
 15
 16
 17
 18
 19
 »

NASA Astrophysics Data System (ADS)
Vishnudas, Subha; Savenije, Hubert H. G.; Van der Zaag, Pieter; Anil, K. R.
A sloping field is not only vulnerable to soil erosion it may also suffer from soil moisture deficiency. Farmers that cultivate on slopes everywhere face similar problems. Conservation technologies may reduce soil and nutrient losses, and thus enhance water holding capacity and soil fertility. But although these technologies promote sustainable crop production on steep slopes, the construction of physical structure such as bench terraces are often labour intensive and expensive to the farmers, since construction and maintenance require high investments. Here we studied the efficiency of coir geotextile with and without crop cultivation in reducing soil moisture deficiency on marginal slopes in Kerala, India. From the results it is evident that the slopes treated with geotextile and crops have the highest moisture retention capacity followed by geotextiles alone, and that the control plot has the lowest moisture retention capacity. As the poor and marginal farmers occupy the highland region, this method provides an economically viable option for income generation and food security along with slope stabilization.

NASA Astrophysics Data System (ADS)
Moustafa, Azza Aziz; Salem, Hesham; Hegazy, Maha; Ali, Omnia
20150201
Simple, accurate, and selective methods have been developed and validated for simultaneous determination of a ternary mixture of Chlorpheniramine maleate (CPM), Pseudoephedrine HCl (PSE) and Ibuprofen (IBF), in tablet dosage form. Four univariate methods manipulating ratio spectra were applied, method A is the double divisorratio difference spectrophotometric method (DDRD). Method B is double divisorderivative ratio spectrophotometric method (DDRD). Method C is derivative ratio spectrumzero crossing method (DRZC), while method D is mean centering of ratio spectra (MCR). Two multivariate methods were also developed and validated, methods E and F are Principal Component Regression (PCR) and Partial Least Squares (PLSs). The proposed methods have the advantage of simultaneous determination of the mentioned drugs without prior separation steps. They were successfully applied to laboratoryprepared mixtures and to commercial pharmaceutical preparation without any interference from additives. The proposed methods were validated according to the ICH guidelines. The obtained results were statistically compared with the official methods where no significant difference was observed regarding both accuracy and precision.

DOT National Transportation Integrated Search
20170905
The Alaska Department of Transportation and Public Facilities (AKDOT&PF) has developed the nations first Geotechnical Asset Management Program. The program encompasses rock slopes, unstable slopes and embankments, retaining walls, and material sou...

DoE optimization of a mercury isotope ratio determination method for environmental studies.
Berni, Alex; Baschieri, Carlo; Covelli, Stefano; Emili, Andrea; Marchetti, Andrea; Manzini, Daniela; Berto, Daniela; Rampazzo, Federico
20160515
By using the experimental design (DoE) technique, we optimized an analytical method for the determination of mercury isotope ratios by means of coldvapor multicollector ICPMS (CVMCICPMS) to provide absolute Hg isotopic ratio measurements with a suitable internal precision. By running 32 experiments, the influence of mercury and thallium internal standard concentrations, total measuring time and sample flow rate was evaluated. Method was optimized varying Hg concentration between 2 and 20 ng g(1). The model finds out some correlations within the parameters affect the measurements precision and predicts suitable sample measurement precisions for Hg concentrations from 5 ng g(1) Hg upwards. The method was successfully applied to samples of Manila clams (Ruditapes philippinarum) coming from the Marano and Grado lagoon (NE Italy), a coastal environment affected by long term mercury contamination mainly due to mining activity. Results show different extents of both mass dependent fractionation (MDF) and mass independent fractionation (MIF) phenomena in clams according to their size and sampling sites in the lagoon. The method is fit for determinations on real samples, allowing for the use of Hg isotopic ratios to study mercury biogeochemical cycles in complex ecosystems. Copyright © 2016 Elsevier B.V. All rights reserved.

Changeinratio methods for estimating population size
Udevitz, Mark S.; Pollock, Kenneth H.; McCullough, Dale R.; Barrett, Reginald H.
20020101
Changeinratio (CIR) methods can provide an effective, low cost approach for estimating the size of wildlife populations. They rely on being able to observe changes in proportions of population subclasses that result from the removal of a known number of individuals from the population. These methods were first introduced in the 1940’s to estimate the size of populations with 2 subclasses under the assumption of equal subclass encounter probabilities. Over the next 40 years, closed population CIR models were developed to consider additional subclasses and use additional sampling periods. Models with assumptions about how encounter probabilities vary over time, rather than between subclasses, also received some attention. Recently, all of these CIR models have been shown to be special cases of a more general model. Under the general model, information from additional samples can be used to test assumptions about the encounter probabilities and to provide estimates of subclass sizes under relaxations of these assumptions. These developments have greatly extended the applicability of the methods. CIR methods are attractive because they do not require the marking of individuals, and subclass proportions often can be estimated with relatively simple sampling procedures. However, CIR methods require a carefully monitored removal of individuals from the population, and the estimates will be of poor quality unless the removals induce substantial changes in subclass proportions. In this paper, we review the state of the art for closed population estimation with CIR methods. Our emphasis is on the assumptions of CIR methods and on identifying situations where these methods are likely to be effective. We also identify some important areas for future CIR research.

Guazzi, Marco; Arena, Ross; Ascione, Aniello; Piepoli, Massimo; Guazzi, Maurizio D
20070501
Increased slope of exercise ventilation to carbon dioxide production (VE/VCO2) is an established prognosticator in patients with heart failure. Recently, the occurrence of exercise oscillatory breathing (EOB) has emerged as an additional strong indicator of survival. The aim of this study is to define the respective prognostic significance of these variables and whether excess risk may be identified when either respiratory disorder is present. In 288 stable chronic HF patients (average left ventricular ejection fraction, 33 +/ 13%) who underwent cardiopulmonary exercise testing, the prognostic relevance of VE/VCO2 slope, EOB, and peak VO2 was evaluated by multivariate Cox regression. During a mean interval of 28 +/ 13 months, 62 patients died of cardiac reasons. Thirtyfive percent presented with EOB. Among patients exhibiting EOB, 54% had an elevated VE/VCO2 slope. The optimal threshold value for the VE/VCO2 slope identified by receiver operating characteristic analysis was < 36.2 or > or = 36.2 (sensitivity, 77%; specificity, 64%; P < .001). Univariate predictors of death included low left ventricular ejection fraction, low peak VO2, high VE/VCO2 slope, and EOB presence. Multivariate analysis selected EOB as the strongest predictor (chi2, 46.5; P < .001). The VE/VCO2 slope (threshold, < 36.2 or > or = 36.2) was the only other exercise test variable retained in the regression (residual chi2, 5.9; P = .02). The hazard ratio for subjects with EOB and a VE/VCO2 slope > or = 36.2 was 11.4 (95% confidence interval, 4.926.5; P < .001). These findings identify EOB as a strong survival predictor even more powerful than VE/VCO2 slope. Exercise oscillatory breathing presence does not necessarily imply an elevated VE/VCO2 slope, but combination of either both yields to a burden of risk remarkably high.

NASA Astrophysics Data System (ADS)
Dementjev, Aleksandr S.; Jovaisa, A.; Silko, Galina; Ciegis, Raimondas
20051101
Based on the developed efficient numerical methods for calculating the propagation of light beams, the alternative methods for measuring the beam radius and propagation ratio proposed in the international standard ISO 11146 are analysed. The specific calculations of the alternative beam propagation ratios Mi2 performed for a number of test beams with a complicated spatial structure showed that the correlation coefficients ci used in the international standard do not establish the universal onetoone relation between the alternative propagation ratios Mi2 and invariant propagation ratios Mσ2 found by the method of moments.

Measuring acoustic emissions in an avalanche slope
NASA Astrophysics Data System (ADS)
Reiweger, Ingrid; Schweizer, Jürg
20140501
Measurements of acoustic emissions are a common technique for monitoring damage and predicting imminent failure of a material. Within natural hazards it has already been used to successfully predict the breakoff of a hanging glacier. To explore the applicability of the acoustic emission (AE) technique for avalanche prediction, we installed two acoustic sensors (with 30 kHz and 60 kHz resonance frequency) in an avalanche prone slope at the Mittelgrat in the Parsenn ski area above Davos, Switzerland. The slope is northeast facing, frequently wind loaded, and approximately 35° steep. The AE signals  in particular the event energy and waiting time distributions  were compared with slope stability. The latter was determined by observing avalanche activity. The results of two winter's measurements yielded that the exponent β of the inverse cumulative distribution of event energy showed a significant drop (from a value of 3.5 to roughly 2.5) at very unstable conditions, i.e. on the three days during our measurement periods when spontaneous avalanches released on our study slope.

Seasonal flows on warm Martian slopes
McEwen, Alfred S.; Ojha, Lujendra; Dundas, Colin M.; Mattson, Sarah S.; Byrne, Shane; Wray, James J.; Cull, Selby C.; Murchie, Scott L.; Thomas, Nicolas; Gulick, Virginia C.
20110101
Water probably flowed across ancient Mars, but whether it ever exists as a liquid on the surface today remains debatable. Recurring slope lineae (RSL) are narrow (0.5 to 5 meters), relatively dark markings on steep (25° to 40°) slopes; repeat images from the Mars Reconnaissance Orbiter High Resolution Imaging Science Experiment show them to appear and incrementally grow during warm seasons and fade in cold seasons. They extend downslope from bedrock outcrops, often associated with small channels, and hundreds of them form in some rare locations. RSL appear and lengthen in the late southern spring and summer from 48°S to 32°S latitudes favoring equatorfacing slopes, which are times and places with peak surface temperatures from ~250 to 300 kelvin. Liquid brines near the surface might explain this activity, but the exact mechanism and source of water are not understood.

Seasonal flows on warm Martian slopes.
McEwen, Alfred S; Ojha, Lujendra; Dundas, Colin M; Mattson, Sarah S; Byrne, Shane; Wray, James J; Cull, Selby C; Murchie, Scott L; Thomas, Nicolas; Gulick, Virginia C
20110805
Water probably flowed across ancient Mars, but whether it ever exists as a liquid on the surface today remains debatable. Recurring slope lineae (RSL) are narrow (0.5 to 5 meters), relatively dark markings on steep (25° to 40°) slopes; repeat images from the Mars Reconnaissance Orbiter High Resolution Imaging Science Experiment show them to appear and incrementally grow during warm seasons and fade in cold seasons. They extend downslope from bedrock outcrops, often associated with small channels, and hundreds of them form in some rare locations. RSL appear and lengthen in the late southern spring and summer from 48°S to 32°S latitudes favoring equatorfacing slopes, which are times and places with peak surface temperatures from ~250 to 300 kelvin. Liquid brines near the surface might explain this activity, but the exact mechanism and source of water are not understood.

Constraining Depositional Slope From Sedimentary Structures in Sandy Braided Streams
NASA Astrophysics Data System (ADS)
Lynds, R. M.; Mohrig, D.; Heller, P. L.
20031201
Determination of paleoslopes in ancient fluvial systems has potentially broad application to quantitatively constraining the history of tectonics and paleoclimate in continental sequences. Our method for calculating paleoslopes for sandy braided streams is based upon a simple physical model that establishes depositional skinfrictional shear stresses from assemblages of sedimentary structures and their associated grain size distributions. The addition of a skinfrictional shear stress, with a geometrically determined formdrag shear stress results in a total boundary shear stress which is directly related to watersurface slope averaged over an appropriate spatial scale. In order to apply this model to ancient fluvial systems, it is necessary to measure the following: coarsest suspended sediment size, finest grain size carried in bed load, flow depth, dune height, and dune length. In the rock record, suspended load and bed load can be accurately assessed by wellpreserved suspended load deposits ("lowenergy" ripples) and bed load deposits (dune foresets). This model predicts an average slope for the North Loup River near Taylor, Nebraska (modern case study) of 2.7 x 103. The measured reachaveraged water surface slope for the same reach of the river is 1.37 x 103. We suggest that it is possible to calculate the depositional slope of a sandy fluvial system by a factor of approximately two. Additionally, preliminary application of this model to the Lower Jurassic Kayenta Formation throughout the Colorado Plateau provides a promising and consistent evaluation of paleoslope in an ancient and wellpreserved, sandy braided stream deposit.

Eros: Shape, topography, and slope processes
Thomas, P.C.; Joseph, J.; Carcich, B.; Veverka, J.; Clark, B.E.; Bell, J.F.; Byrd, A.W.; Chomko, R.; Robinson, M.; Murchie, S.; Prockter, L.; Cheng, A.; Izenberg, N.; Malin, M.; Chapman, C.; McFadden, L.A.; Kirk, R.; Gaffey, M.; Lucey, P.G.
20020101
Stereogrammetric measurement of the shape of Eros using images obtained by NEAR's Multispectral Imager provides a survey of the major topographic features and slope processes on this asteroid. This curved asteroid has radii ranging from 3.1 to 17.7 km and a volume of 2535 ?? 20 km3. The center of figure is within 52 m of the center of mass provided by the Navigation team; this minimal difference suggests that there are only modest variations in density or porosity within the asteroid. Three large depressions 10, 8, and 5.3 km across represent different stages of degradation of large impact craters. Slopes on horizontal scales of ???300 m are nearly all less than 35??, although locally scarps are much steeper. The area distribution of slopes is similar to those on Ida, Phobos, and Deimos. Regions that have slopes greater than 25?? have distinct brighter markings and have fewer large ejecta blocks than do flatter areas. The albedo patterns that suggest downslope transport of regolith have sharper boundaries than those on Phobos, Deimos, and Gaspra. The morphology of the albedo patterns, their lack of discrete sources, and their concentration on steeper slopes suggest transport mechanisms different from those on the previously wellobserved small bodies, perhaps due to a reduced relative effectiveness of impact gardening on Eros. Regolith is also transported in talus cones and in connected, sinuous paths extending as much as 2 km, with some evident as relatively darker material. Talus material in at least one area is a discrete superposed unit, a feature not resolved on other small bodies. Flatfloored craters that apparently contain ponded material also suggest discrete units that are not well mixed by impacts. ?? 2002 Elsevier Science (USA).

Rippled Surfaces on a Slope in Coloe Fossae
20140109
This observation from NASA Mars Reconnaissance Orbiter shows a set of landforms that appears to form a nested chevron pattern on a slope in Coloe Fossae. Interestingly, nearby surfaces on the same slope are all parallel.

DOT National Transportation Integrated Search
20110401
This Manual is intended to provide guidance for the design of rock cut slopes, rockfall catchment, and : rockfall controls. Recommendations presented in this manual are based on research presented in Shakoor : and Admassu (2010) entitled Rock Slop...

DOT National Transportation Integrated Search
20100601
Based on the stratigraphy and the type of slope stability problems, the flat lying, Paleozoic age, sedimentary : rocks of Ohio were divided into three design units: 1) competent rock design unit consisting of sandstones, limestones, : and siltstones ...

Unstable slope management program.
DOT National Transportation Integrated Search
20090801
This Rapid Response Project gathered information on existing unstable slope management programs, with a : focus on asset management practices in the United States and overseas. On the basis of this study, the research : team summarized and recommende...

Velocity of water flow along saturated loess slopes under erosion effects
NASA Astrophysics Data System (ADS)
Huang, Yuhan; Chen, Xiaoyan; Li, Fahu; Zhang, Jing; Lei, Tingwu; Li, Juan; Chen, Ping; Wang, Xuefeng
20180601
Rainfall or snowmelted water recharge easily saturates loose top soils with a less permeable underlayer, such as cultivated soil slope and partially thawed top soil layer, and thus, may influence the velocity of water flow. This study suggested a methodology and device system to supply water from the bottom soil layer at the different locations of slopes. Water seeps into and saturates the soil, when the water level is controlled at the same height of the soil surface. The structures and functions of the device, the components, and the operational principles are described in detail. A series of laboratory experiments were conducted under slope gradients of 5°, 10°, 15°, and 20° and flow rates of 2, 4, and 8 L min1 to measure the water flow velocities over eroding and noneroded loess soil slopes, under saturated conditions by using electrolyte tracing. Results showed that flow velocities on saturated slopes were 17% to 88% greater than those on nonsaturated slopes. Flow velocity increased rapidly under high flow rates and slope gradients. Saturation conditions were suitable in maintaining smooth rill geomorphology and causing fast water flow. The saturated soil slope had a lubricant effect on the soil surface to reduce the frictional force, resulting in high flow velocity. The flow velocities of eroding rills under different slope gradients and flow rates were approximately 14% to 33% lower than those of noneroded rills on saturated loess slopes. Compared with that on a saturated loess slope, the eroding rill on a nonsaturated loess slope can produce headcuts to reduce the flow velocity. This study helps understand the hydrodynamics of soil erosion and sediment transportation of saturated soil slopes.

Intrusions of Kuroshio and Shelf Waters on Northern Slope of South China Sea in Summer 2015
NASA Astrophysics Data System (ADS)
Li, Denghui; Zhou, Meng; Zhang, Zhaoru; Zhong, Yisen; Zhu, Yiwu; Yang, Chenghao; Xu, Mingquan; Xu, Dongfeng; Hu, Ziyuan
20180601
The northern slope region of the South China Sea (SCS) is a biological hot spot characterized by high primary productivity and biomasses transported by crossshelf currents, which support the spawning and growth of commercially and ecologically important fish species. To understand the physical and biogeochemical processes that promote the high primary production of this region, we conducted a cruise from June 10 and July 2, 2015. In this study, we used fuzzy cluster analysis and optimum multiparameter analysis methods to analyze the hydrographic data collected during the cruise to determine the compositions of the upper 55m water masses on the SCS northern slope and thereby elucidate the crossslope transport of shelf water (SHW) and the intrusions of Kuroshio water (KW). We also analyzed the geostrophic currents derived from acoustic Doppler current profiler measurements and satellite data. The results reveal the surface waters on the northern slope of the SCS to be primarily composed of waters originating from South China Sea water (SCSW), KW, and SHW. The SCSW dominated a majority of the study region at percentages ranging between 60% and 100%. We found a strong crossslope current with speeds greater than 50 cm s1 to have carried SHW into and through the surveyed slope area, and KW to have intruded onto the slope via mesoscale eddies, thereby dominating the southwestern section of the study area.

Harvesting impacts on steep slopes in Virginia
W.B. Stuart; S.L. Carr
19910101
Ten tracts in the mountains of western Virginia were intensively sampled to determine the type and extent of soil disturbance from groundbased logging and the attendant erosion risk. Average slopes for the tracts ranged from 21 to 43 percent. Logged slopes exceeded 50 percent. All tracts surveyed were logged prior to the push for voluntary Best Management Practices...

NASA Astrophysics Data System (ADS)
Colangelo, Antonio C.
20100501
The central purpose of this work is to perform a reverse procedure in the mass movement conventional parameterization approach. The idea is to generate a number of synthetic mass movements by means of the "slope stability simulator" (Colangelo, 2007), and compeer their morphological and physical properties with "real" conditions of effective mass movements. This device is an integrated part of "relief unity emulator" (rue), that permits generate synthetic mass movements in a synthetic slope environment. The "rue" was build upon fundamental geomorphological concepts. These devices operate with an integrated set of mechanical, geomorphic and hydrological models. The "slope stability simulator" device (sss) permits to perform a detailed slope stability analysis in a theoretical three dimensional space, by means of evaluation the spatial behavior of critical depths, gradients and saturation levels in the "potential rupture surfaces" inferred along a set of slope profiles, that compounds a synthetic slope unity. It's a metastable 4dimensional object generated by means of "rue", that represents a sequence evolution of a generator profile applied here, was adapted the infinite slope model for slope. Any slope profiles were sliced by means of finite element solution like in Bishop method. For the synthetic slope systems generated, we assume that the potential rupture surface occurs at soilregolith or soilrock boundary in slope material. Sixteen variables were included in the "ruesss" device that operates in an integrated manner. For each cell, the factor of safety was calculated considering the value of shear strength (cohesion and friction) of material, soilregolith boundary depth, soil moisture level content, potential rupture surface gradient, slope surface gradient, top of subsurface flow gradient, apparent soil bulk density and vegetation surcharge. The slope soil was considered as cohesive material. The 16 variables incorporated in the models were analyzed for
 «
 15
 16
 17
 18
 19
 »
 «
 16
 17
 18
 19
 20
 »

Isotopic Ratio, Isotonic Ratio, Isobaric Ratio and Shannon Information Uncertainty
NASA Astrophysics Data System (ADS)
Ma, ChunWang; Wei, HuiLing
20141101
The isoscaling and the isobaric yield ratio difference (IBD) probes, both of which are constructed by yield ratio of fragment, provide cancelation of parameters. The information entropy theory is introduced to explain the physical meaning of the isoscaling and IBD probes. The similarity between the isoscaling and IBD results is found, i.e., the information uncertainty determined by the IBD method equals to β  α determined by the isoscaling (α (β) is the parameter fitted from the isotopic (isotonic) yield ratio).

Correction of broadband snow albedo measurements affected by unknown slope and sensor tilts
NASA Astrophysics Data System (ADS)
Weiser, Ursula; Olefs, Marc; Schöner, Wolfgang; Weyss, Gernot; Hynek, Bernhard
20160401
Geometric effects induced by the underlying terrain slope or by tilt errors of the radiation sensors lead to an erroneous measurement of snow or ice albedo. Consequently, artificial diurnal albedo variations in the order of 120 % are observed. The present paper proposes a general method to correct tilt errors of albedo measurements in cases where tilts of both the sensors and the slopes are not accurately measured or known. We demonstrate that atmospheric parameters for this correction model can either be taken from a nearby wellmaintained and horizontally levelled measurement of global radiation or alternatively from a solar radiation model. In a next step the model is fitted to the measured data to determine tilts and directions of sensors and the underlying terrain slope. This then allows us to correct the measured albedo, the radiative balance and the energy balance. Depending on the direction of the slope and the sensors a comparison between measured and corrected albedo values reveals obvious over or underestimations of albedo. It is also demonstrated that differences between measured and corrected albedo are generally highest for large solar zenith angles.

Hofheinz, Frank; Hoff, Jörg van den; Steffen, Ingo G; Lougovski, Alexandr; Ego, Kilian; Amthauer, Holger; Apostolova, Ivayla
20161201
We have demonstrated recently that the tumortoblood standard uptake ratio (SUR) is superior to tumor standardized uptake value (SUV) as a surrogate of the metabolic uptake rate K m of fluorodeoxyglucose (FDG), overcoming several of the known shortcomings of the SUV approach: excellent linear correlation of SUR and K m from Patlak analysis was found using dynamic imaging of liver metastases. However, due to the perfectly standardized uptake period used for SUR determination and the comparatively short uptake period, these results are not automatically valid and applicable for clinical wholebody examinations in which the uptake periods (T) are distinctly longer and can vary considerably. Therefore, the aim of this work was to investigate the correlation between SUR derived from clinical static wholebody scans and K msurrogate derived from dual time point (DTP) measurements. DTP (18)FFDG PET/CT was performed in 90 consecutive patients with histologically proven nonsmall cell lung cancer (NSCLC). In the PET images, the primary tumor was delineated with an adaptive threshold method. For determination of the blood SUV, an aorta region of interest (ROI) was delineated manually in the attenuation CT and transferred to the PET image. Blood SUV was computed as the mean value of the aorta ROI. SUR values were computed as ratio of tumor SUV and blood SUV. SUR values from the early time point of each DTP measurement were scan time corrected to 75 min postinjection (SURtc). As surrogate of K m, we used the SUR(T) slope, K slope, derived from DTP measurements since it is proportional to the latter under the given circ*mstances. The correlation of SUV and SURtc with K slope was investigated. The prognostic value of SUV, SURtc, and K slope for overall survival (OS) and progressionfree survival (PFS) was investigated with univariate Cox regression in a hom*ogeneous subgroup (N=31) treated with primary chemoradiation. Correlation analysis revealed for both, SUV and SURtc, a

Infinite slope stability under steady unsaturated seepage conditions
Lu, Ning; Godt, Jonathan W.
20080101
We present a generalized framework for the stability of infinite slopes under steady unsaturated seepage conditions. The analytical framework allows the water table to be located at any depth below the ground surface and variation of soil suction and moisture content above the water table under steady infiltration conditions. The framework also explicitly considers the effect of weathering and porosity increase near the ground surface on changes in the friction angle of the soil. The factor of safety is conceptualized as a function of the depth within the vadose zone and can be reduced to the classical analytical solution for subaerial infinite slopes in the saturated zone. Slope stability analyses with hypothetical sandy and silty soils are conducted to illustrate the effectiveness of the framework. These analyses indicate that for hillslopes of both sandy and silty soils, failure can occur above the water table under steady infiltration conditions, which is consistent with some field observations that cannot be predicted by the classical infinite slope theory. A case study of shallow slope failures of sandy colluvium on steep coastal hillslopes near Seattle, Washington, is presented to examine the predictive utility of the proposed framework.

Improved modified energy ratio method using a multiwindow approach for accurate arrival picking
NASA Astrophysics Data System (ADS)
Lee, Minho; Byun, Joongmoo; Kim, Dowan; Choi, Jihun; Kim, Myungsun
20170401
To identify accurately the location of microseismic events generated during hydraulic fracture stimulation, it is necessary to detect the first break of the P and Swave arrival times recorded at multiple receivers. These microseismic data often contain highamplitude noise, which makes it difficult to identify the P and Swave arrival times. The shorttermaverage to longtermaverage (STA/LTA) and modified energy ratio (MER) methods are based on the differences in the energy densities of the noise and signal, and are widely used to identify the Pwave arrival times. The MER method yields more consistent results than the STA/LTA method for data with a low signaltonoise (S/N) ratio. However, although the MER method shows good results regardless of the delay of the signal wavelet for signals with a high S/N ratio, it may yield poor results if the signal is contaminated by highamplitude noise and does not have the minimum delay. Here we describe an improved MER (IMER) method, whereby we apply a multiplewindowing approach to overcome the limitations of the MER method. The IMER method contains calculations of an additional MER value using a third window (in addition to the original MER window), as well as the application of a moving average filter to each MER data point to eliminate highfrequency fluctuations in the original MER distributions. The resulting distribution makes it easier to apply thresholding. The proposed IMER method was applied to synthetic and real datasets with various S/N ratios and mixeddelay wavelets. The results show that the IMER method yields a high accuracy rate of around 80% within five sample errors for the synthetic datasets. Likewise, in the case of real datasets, 94.56% of the Pwave picking results obtained by the IMER method had a deviation of less than 0.5 ms (corresponding to 2 samples) from the manual picks.

Robust Regression for Slope Estimation in CurriculumBased Measurement Progress Monitoring
ERIC Educational Resources Information Center
Mercer, Sterett H.; Lyons, Alina F.; Johnston, Lauren E.; Millhoff, Courtney L.
20150101
Although ordinary leastsquares (OLS) regression has been identified as a preferred method to calculate rates of improvement for individual students during curriculumbased measurement (CBM) progress monitoring, OLS slope estimates are sensitive to the presence of extreme values. Robust estimators have been developed that are less biased by…

NASA Astrophysics Data System (ADS)
Hassan, Said A.; Elzanfaly, Eman S.; Salem, Maissa Y.; ElZeany, Badr A.
20160101
A novel spectrophotometric method was developed for determination of ternary mixtures without previous separation, showing significant advantages over conventional methods. The new method is based on mean centering of double divisor ratio spectra. The mathematical explanation of the procedure is illustrated. The method was evaluated by determination of model ternary mixture and by the determination of Amlodipine (AML), Aliskiren (ALI) and Hydrochlorothiazide (HCT) in laboratory prepared mixtures and in a commercial pharmaceutical preparation. For proper presentation of the advantages and applicability of the new method, a comparative study was established between the new mean centering of double divisor ratio spectra (MCDD) and two similar methods used for analysis of ternary mixtures, namely mean centering (MC) and double divisor of ratio spectraderivative spectrophotometry (DDRSDS). The method was also compared with a reported one for analysis of the pharmaceutical preparation. The method was validated according to the ICH guidelines and accuracy, precision, repeatability and robustness were found to be within the acceptable limits.

Heliostat field cost reduction by `slope drive' optimization
NASA Astrophysics Data System (ADS)
Arbes, Florian; Weinrebe, Gerhard; Wöhrbach, Markus
20160501
An algorithm to optimize power tower heliostat fields employing heliostats with socalled slope drives is presented. It is shown that a field using heliostats with the slope drive axes configuration has the same performance as a field with conventional azimuthelevation tracking heliostats. Even though heliostats with the slope drive configuration have a limited tracking range, field groups of heliostats with different axes or different drives are not needed for different positions in the heliostat field. The impacts of selected parameters on a benchmark power plant (PS10 near Seville, Spain) are analyzed.

Karstic slope "breathing": morphostructural influence and hazard implications
NASA Astrophysics Data System (ADS)
Devoti, Roberto; Falcucci, Emanuela; Gori, Stefano; Eliana Poli, Maria; Zanferrari, Adriano; Braitenberg, Carla; Fabris, Paolo; Grillo, Barbara; Zuliani, David
20160401
The study refers to the active slope deformation detected by GPS and tiltmeter stations in the Cansiglio karstic plateau located in the western Carnic Prealps (NE Italy). The observed transient deformation clearly correlates with the rainfall, so that the southernmost border of the Plateau reacts instantly to heavy rains displaying a "back and forth" deformation up to a few centimeters wide, with different time constants, demonstrating a response to different catchment volumes. We carried out a field survey along the southern Cansiglio slope, to achieve structural characterization of the relief and to verify the possible relation between structural features and the peculiar geomorphological setting dominated by widespread karstic features. The Cansiglio plateau develops on the frontal ramp anticline of the Cansiglio thrust, an about ENEWSW trending, SSEverging, low angle thrust, belonging to the NeogeneQuaternary front of the eastern Southern Alps. The Cansiglio thrust outcrops at the base of the Cansiglio plateau, where it overlaps the Mesozoic carbonates on the MioceneQuaternary terrigenous succession. All along its length cataclastic limestone largely outcrop. The Cansiglio thrust is bordered by two transfer zones probably inherited from the Mesozoic paleogeography: the Caneva fault in the west and the Col Longone fault in the east. The carbonatic massif is also characterized by a series of about northward steeply dipping reverse minor faults and a set of subvertical joints parallel to the axes of the Cansiglio anticline. Other NNWSSE and NNESSW conjugate faults and fractures perpendicular to the Cansiglio southern slope are also identified. This structural setting affect pervasively the whole slope and may determine centimetre to metrescale rock prisms. Interestingly, along the topmost portion of the slope, some dolines and swallow holes show an incipient coalescence, that trends parallel to the massif front and to the deformation zones related to the

Direction of Auditory PitchChange Influences Visual Search for Slope From Graphs.
Parrott, Stacey; GuzmanMartinez, Emmanuel; Orte, Laura; Grabowecky, Marcia; Huntington, Mark D; Suzuki, Satoru
20150101
Linear trend (slope) is important information conveyed by graphs. We investigated how sounds influenced slope detection in a visual search paradigm. Four bar graphs or scatter plots were presented on each trial. Participants looked for a positiveslope or a negativeslope target (in blocked trials), and responded to targets in a go or nogo fashion. For example, in a positiveslopetarget block, the target graph displayed a positive slope while other graphs displayed negative slopes (a go trial), or all graphs displayed negative slopes (a nogo trial). When an ascending or descending sound was presented concurrently, ascending sounds slowed detection of negativeslope targets whereas descending sounds slowed detection of positiveslope targets. The sounds had no effect when they immediately preceded the visual search displays, suggesting that the results were due to crossmodal interaction rather than priming. The sounds also had no effect when targets were words describing slopes, such as "positive," "negative," "increasing," or "decreasing," suggesting that the results were unlikely due to semanticlevel interactions. Manipulations of spatiotemporal similarity between sounds and graphs had little effect. These results suggest that ascending and descending sounds influence visual search for slope based on a general association between the direction of auditory pitchchange and visual linear trend.

Humaninduced geomorphology: Modeling slope failure in Dominical, Costa Rica using Landsat imagery
NASA Astrophysics Data System (ADS)
Miller, Andrew J.
Unchecked human development has ravaged the region between Dominical and Uvita, Costa Rica. Much of the development transition has been driven by tourism and further foreign direct investment in residential, service and commercial enterprises. The resulting landuse/landcover change has removed traditional forest cover in exchange for impervious surfaces, physical structures, and bare ground which is no longer mechanically supported by woody vegetation. Combined with a tropical climate, deeply weathered soils and lithography which are prone to erosion, land cover change has led to an increase in slope failure occurrences. Given the remoteness of the DominicalUvita region, its rate of growth and the lack of monitoring, new techniques for monitoring land use and slope failure susceptibility are needed. Two new indices are presented here that employ a Digital Elevation Model (DEM) and widely available Landsat imagery to assist in this endeavor. The first index, or Vegetation Influenced Landslide Index (VILI), incorporates slope derived from a DEM and Lu et al.'s (2007) Surface Cover Index to quantify vegetative cover as a means of mechanical stabilization in landslide prone areas. The second index, or Slope Multiplier Index (SMI), uses individual Landsat data bands and basic Landsat band ratios as environmental proxies to replicate soil, vegetative and hydrologic properties. Both models achieve accuracy over 70% and rival results from more complicated published literature. The accuracy of the indices was assessed with the creation of a landslide inventory developed from field observations occurring in December 2007 and November 2008. The creation of these indices represents an efficient and accurate way of determining landslide susceptibility zonation in data poor areas where environmental protection practitioners may be overextended, undertrained or both.

NASA Astrophysics Data System (ADS)
Kang, Fei; Li, Junjie; Ma, Zhenyue
20130201
Determination of the critical slip surface with the minimum factor of safety of a slope is a difficult constrained global optimization problem. In this article, an artificial bee colony algorithm with a multislice adjustment method is proposed for locating the critical slip surfaces of soil slopes, and the Spencer method is employed to calculate the factor of safety. Six benchmark examples are presented to illustrate the reliability and efficiency of the proposed technique, and it is also compared with some wellknown or recent algorithms for the problem. The results show that the new algorithm is promising in terms of accuracy and efficiency.

[Analysis of related factors of slope plant hyperspectral remote sensing].
Sun, WeiQi; Zhao, YunSheng; Tu, LinLing
20140901
In the present paper, the slope gradient, aspect, detection zenith angle and plant types were analyzed. In order to strengthen the theoretical discussion, the research was under laboratory condition, and modeled uniform slope for slope plant. Through experiments we found that these factors indeed have influence on plant hyperspectral remote sensing. When choosing slope gradient as the variate, the blade reflection first increases and then decreases as the slope gradient changes from 0° to 36°; When keeping other factors constant, and only detection zenith angle increasing from 0° to 60°, the spectral characteristic of slope plants do not change significantly in visible light band, but decreases gradually in near infrared band; With only slope aspect changing, when the dome meets the light direction, the blade reflectance gets maximum, and when the dome meets the backlit direction, the blade reflectance gets minimum, furthermore, setting the line of vertical intersection of incidence plane and the dome as an axis, the reflectance on the axis's both sides shows symmetric distribution; In addition, spectral curves of different plant types have a lot differences between each other, which means that the plant types also affect hyperspectral remote sensing results of slope plants. This research breaks through the limitations of the traditional vertical remote sensing data collection and uses the multiangle and hyperspectral information to analyze spectral characteristics of slope plants. So this research has theoretical significance to the development of quantitative remote sensing, and has application value to the plant remote sensing monitoring.

Stability of sulfur slopes on Io
NASA Technical Reports Server (NTRS)
Clow, G. D.; Carr, M. H.
19800101
The mechanical properties of elemental sulfur are such that the upper crust of Io cannot be primarily sulfur. For heat flows in the range 1001000 ergs/sq cm sec sulfur becomes ductile within several hundred meters of the surface and would prevent the formation of calderas with depths greater than this. However, the one caldera for which precise depth data are available is 2 km deep, and this value may be typical. A study of the mechanical equilibrium of simple slopes shows that the depth to the zone of rapid ductile flow strongly controls the maximum heights for sulfur slopes. Sulfur scarps with heights greater than 1 km will fail for all heat flows greater than 180 ergs/sq cm sec and slope angles greater than 22.5 deg. The observed relief on Io is inconsistent with that anticipated for a predominantly sulfur crust. However, a silicate crust with several percent sulfur included satisfies both the mechanical constraints and the observed presence of sulfur on Io.

An Analysis of Students' Mistakes on Routine Slope Tasks
ERIC Educational Resources Information Center
Cho, Peter; Nagle, Courtney
20170101
This study extends past research on students' understanding of slope by analyzing college students' mistakes on routine tasks involving slope. We conduct quantitative and qualitative analysis of students' mistakes to extract information regarding slope conceptualizations described in prior research. Results delineate procedural proficiencies and…

NASA Astrophysics Data System (ADS)
Demopoulos, A. W.; Bourque, J. R.; Brooke, S.
20151201
Hydrocarbon seeps support distinct benthic communities capable of utilizing reduced chemical compounds for nutrition. In recent years, methane seepage has been increasingly documented along the continental slope of the U.S. Atlantic margin. In 2012 and 2013, two seeps were investigated in this region: a shallow site near Baltimore Canyon (410450 m) and a deep site near Norfolk Canyon (1600 m). Both sites contain extensive mussel beds and microbial mats. Sediment cores and grab samples were collected to quantify the abundance, diversity, and community structure of benthic macrofauna (>300 mm) in relationship to the associated sediment environment (organic carbon and nitrogen, stable isotopes 13C and 15N, grain size, and depth) of mussel beds, mats, and slope habitats. Macrofaunal densities in microbial mats were four times greater than those present in mussel beds and slope sediments. Macrofaunal communities were distinctly different both between depths and among habitat types. Specifically, microbial mat sediments were dominated by the annelid families Dorvilleidae, Capitellidae, and Tubificidae, while mussel habitats had higher proportions of crustaceans. Diversity was lower in Baltimore microbial mat habitats, but higher in mussel and slope sediments compared to Norfolk seep habitats found at deeper depths. Multivariate statistical analysis identified sediment carbon:nitrogen (C:N) ratios and 13C values as important variables for structuring the macrofaunal communities. Higher C:N ratios were present within microbial mat habitats and depleted 13C values occurred in sediments adjacent to mussel beds found in Norfolk Canyon seeps. Differences in the quality and source of organic matter present in the seep habitats are known to be important drivers in macrofaunal community structure and associated food webs. The multivariate analysis provides new insight into the relative importance of the seep sediment quality in supporting dense macrofaunal communities compared

ByungDae Park; Charles R. Frihart; Yan Yu; Adya P. Singh
20130101
To understand the influence of formaldehyde/urea (F/U) mole ratio on the properties of ureaâformaldehyde (UF) resins, this study investigated hardness of cured UF resins with different F/U mole ratios using a nanoindentation method. The traditional Brinell hardness (HB) method was also used...

Rodrigues, João Fabrício Mota; Coelho, Marco Túlio Pacheco
20160101
Sampling the biodiversity is an essential step for conservation, and understanding the efficiency of sampling methods allows us to estimate the quality of our biodiversity data. Sex ratio is an important population characteristic, but until now, no study has evaluated how efficient are the sampling methods commonly used in biodiversity surveys in estimating the sex ratio of populations. We used a virtual ecologist approach to investigate whether active and passive capture methods are able to accurately sample a population's sex ratio and whether differences in movement pattern and detectability between males and females produce biased estimates of sexratios when using these methods. Our simulation allowed the recognition of individuals, similar to markrecapture studies. We found that differences in both movement patterns and detectability between males and females produce biased estimates of sex ratios. However, increasing the sampling effort or the number of sampling days improves the ability of passive or active capture methods to properly sample sex ratio. Thus, prior knowledge regarding movement patterns and detectability for species is important information to guide field studies aiming to understand sex ratio related patterns.

Rodrigues, João Fabrício Mota; Coelho, Marco Túlio Pacheco
20160101
Sampling the biodiversity is an essential step for conservation, and understanding the efficiency of sampling methods allows us to estimate the quality of our biodiversity data. Sex ratio is an important population characteristic, but until now, no study has evaluated how efficient are the sampling methods commonly used in biodiversity surveys in estimating the sex ratio of populations. We used a virtual ecologist approach to investigate whether active and passive capture methods are able to accurately sample a population’s sex ratio and whether differences in movement pattern and detectability between males and females produce biased estimates of sexratios when using these methods. Our simulation allowed the recognition of individuals, similar to markrecapture studies. We found that differences in both movement patterns and detectability between males and females produce biased estimates of sex ratios. However, increasing the sampling effort or the number of sampling days improves the ability of passive or active capture methods to properly sample sex ratio. Thus, prior knowledge regarding movement patterns and detectability for species is important information to guide field studies aiming to understand sex ratio related patterns. PMID:27441554

NASA Astrophysics Data System (ADS)
Kubota, Tetsuya; Prasad Paudel, Prem
20160401
In 2013, some landslides induced by heavy rainfalls occurred in southern part of Kathmandu, Nepal which is located southern suburb of Kathmandu, the capital. These landslide slopes hit by the strong Gorkha Earthquake in April 2015 and seemed to destabilize again. Hereby, to clarify their susceptibility of landslide in the earthquake, one of these landslide slopes was analyzed its slope stability by CSSDP (Critical Slip Surface analysis by Dynamic Programming based on limit equilibrium method, especially Janbu method) against slope failure with various seismic acceleration observed around Kathmandu in the Gorkha Earthquake. The CSSDP can detect the landslide slip surface which has minimum Fs (factor of safety) automatically using dynamic programming theory. The geology in this area mainly consists of fragile schist and it is prone to landslide occurrence. Field survey was conducted to obtain topological data such as ground surface and slip surface cross section. Soil parameters obtained by geotechnical tests with field sampling were applied. Consequently, the slope has distinctive characteristics followings in terms of slope stability: (1) With heavy rainfall, it collapsed and had a factor of safety Fs <1.0 (0.654 or more). (2) With seismic acceleration of 0.15G (147gal) observed around Kathmandu, it has Fs=1.34. (3) With possible local seismic acceleration of 0.35G (343gal) estimated at Kathmandu, it has Fs=0.989. If it were very shallow landslide and covered with cedars, it could have Fs =1.055 due to root reinforcement effect to the soil strength. (4) Without seismic acceleration and with no rainfall condition, it has Fs=1.75. These results can explain the real landslide occurrence in this area with the maximum seismic acceleration estimated as 0.15G in the vicinity of Kathmandu by the Gorkha Earthquake. Therefore, these results indicate landslide susceptibility of the slopes in this area with strong earthquake. In this situation, it is possible to predict
 «
 16
 17
 18
 19
 20
 »
 «
 17
 18
 19
 20
 21
 »

Assessment of cropland area on sloping land in DPRK
NASA Astrophysics Data System (ADS)
Kerdiles, H.; Spyratos, S.; Gallego, F. J.
20140301
Following the famines of the mid 1990s, the government of the Democratic People's Republic of Korea (DPRK) authorized cultivation on sloping land before deciding, in the years 2000, to limit this practice on slopes above 15 degrees in order to reduce erosion. There are still many cultivated fields on slopes and their total estimated area ranges from 300,000 ha to more than 2 million ha. This study aims at assessing cropland areas on slopes above 10 and 15 degrees by using high to very high resolution remote sensing satellite imagery. For this purpose, a grid of points was superimposed over the DPRK territory and stratified according to slope, as derived from two DEMs, the 30 m ASTER GDEM V2 and the 3 arc second (~90 m) SRTM Dem V4. A sample of about 2100 points was drawn using an optimal allocation sampling plan, based on a preliminary assessment of the variance of the estimated cropland percentage per class of slope. These 2100 points were interpreted into cropland, no cropland and doubt using mostly Google Earth imagery acquired after 2004. For slopes above 10 degrees, the area cropped was estimated to be around 1,000,000 ha (5.6% CV) and 742,000 ha (8.1% CV) according to the ASTER and SRTM DEM respectively. Above 15 degrees, the estimated cropland area ranges from 360,000 ha (9.7% CV) with SRTM to 540,000 ha (6.6.% CV) with ASTER. To decide between these two estimations, a validation of the two DEMs should be carried out on a region with similar relief. Alternatively, a higher accuracy DEM such as the one to be derived from the TanDEMX mission in 2014 should provide more accurate estimates of the cropland area on sloping land.

Dark matter contraction and stellarmasstolight ratio gradients in massive earlytype galaxies
NASA Astrophysics Data System (ADS)
Oldham, Lindsay J.; Auger, Matthew W.
20180501
We present models for the dark and luminous mass structure of 12 strong lensing earlytype galaxies. We combine pixelbased modelling of multiband Hubble Space Telescope imaging with Jeans modelling of kinematics obtained from Keck/ESI spectra to disentangle the dark and luminous contributions to the mass. Assuming a generalised NFW (gNFW) profile for the dark matter halo and a spatially constant stellarmasstolight ratio ϒ⋆ for the baryonic mass, we infer distributions for ϒ⋆ consistent with initial mass functions (IMFs) that are heavier than the Milky Way's (with a global mean mismatch parameter relative to a Chabrier IMF μαc = 1.80 ± 0.14) and halo inner density slopes that span a large range but are generally cuspier than the darkmatteronly prediction (μ _{γ ^' }} = 2.01_{0.22}^{+0.19}). We investigate possible reasons for overestimating the halo slope, including the neglect of spatially varying stellarmasstolight ratios and/or stellar orbital anisotropy, and find that a quarter of the systems prefer radially declining stellarmasstolight ratio gradients, but that the overall effect on our inference on the halo slope is small. We suggest a coherent explanation of these results in the context of insideout galaxy growth, and that the relative importance of different baryonic processes in shaping the dark halo may depend on halo environment.

NASA Astrophysics Data System (ADS)
Yilmaz, Işık
20090601
The purpose of this study is to compare the landslide susceptibility mapping methods of frequency ratio (FR), logistic regression and artificial neural networks (ANN) applied in the Kat County (Tokat—Turkey). Digital elevation model (DEM) was first constructed using GIS software. Landsliderelated factors such as geology, faults, drainage system, topographical elevation, slope angle, slope aspect, topographic wetness index (TWI) and stream power index (SPI) were used in the landslide susceptibility analyses. Landslide susceptibility maps were produced from the frequency ratio, logistic regression and neural networks models, and they were then compared by means of their validations. The higher accuracies of the susceptibility maps for all three models were obtained from the comparison of the landslide susceptibility maps with the known landslide locations. However, respective area under curve (AUC) values of 0.826, 0.842 and 0.852 for frequency ratio, logistic regression and artificial neural networks showed that the map obtained from ANN model is more accurate than the other models, accuracies of all models can be evaluated relatively similar. The results obtained in this study also showed that the frequency ratio model can be used as a simple tool in assessment of landslide susceptibility when a sufficient number of data were obtained. Input process, calculations and output process are very simple and can be readily understood in the frequency ratio model, however logistic regression and neural networks require the conversion of data to ASCII or other formats. Moreover, it is also very hard to process the large amount of data in the statistical package.

Speaking rate effects on locus equation slope.
Berry, Jeff; Weismer, Gary
20131101
A locus equation describes a 1st order regression fit to a scatter of vowel steadystate frequency values predicting vowel onset frequency values. Locus equation coefficients are often interpreted as indices of coarticulation. Speaking rate variations with a constant consonantvowel form are thought to induce changes in the degree of coarticulation. In the current work, the hypothesis that locus slope is a transparent index of coarticulation is examined through the analysis of acoustic samples of largescale, nearly continuous variations in speaking rate. Following the methodological conventions for locus equation derivation, data pooled across ten vowels yield locus equation slopes that are mostly consistent with the hypothesis that locus equations vary systematically with coarticulation. Comparable analyses between different fourvowel pools reveal variations in the locus slope range and changes in locus slope sensitivity to rate change. Analyses across rate but within vowels are substantially less consistent with the locus hypothesis. Taken together, these findings suggest that the practice of vowel pooling exerts a nonnegligible influence on locus outcomes. Results are discussed within the context of articulatory accounts of locus equations and the effects of speaking rate change.

Slope stability and rockfall assessment of volcanic tuffs using RPAS with 2D FEM slope modelling
NASA Astrophysics Data System (ADS)
Török, Ákos; Barsi, Árpád; Bögöly, Gyula; Lovas, Tamás; Somogyi, Árpád; Görög, Péter
20180201
Steep, hardly accessible cliffs of rhyolite tuff in NE Hungary are prone to rockfalls, endangering visitors of a castle. Remote sensing techniques were employed to obtain data on terrain morphology and to provide slope geometry for assessing the stability of these rock walls. A RPAS (Remotely Piloted Aircraft System) was used to collect images which were processed by Pix4D mapper (structure from motion technology) to generate a point cloud and mesh. The georeferencing was made by Global Navigation Satellite System (GNSS) with the use of seven ground control points. The obtained digital surface model (DSM) was processed (vegetation removal) and the derived digital terrain model (DTM) allowed cross sections to be drawn and a joint system to be detected. Joint and discontinuity system was also verified by field measurements. Onsite tests as well as laboratory tests provided additional engineering geological data for slope modelling. Stability of cliffs was assessed by 2D FEM (finite element method). Global analyses of cross sections show that weak intercalating tuff layers may serve as potential slip surfaces. However, at present the greatest hazard is related to planar failure along ENEWSW joints and to wedge failure. The paper demonstrates that RPAS is a rapid and useful tool for generating a reliable terrain model of hardly accessible cliff faces. It also emphasizes the efficiency of RPAS in rockfall hazard assessment in comparison with other remote sensing techniques such as terrestrial laser scanning (TLS).

DOE Office of Scientific and Technical Information (OSTI.GOV)
Schwab, W.C.; Danforth, W.W.; Scanlon, K.M.
19900601
An amphitheatershaped scarp, approximately 55 km across in water depths from about 3,000 m to 6,700 m was imaged on the northern insular slope of Puerto Rico (southern slope of the Puerto Rico Trench) using the GLORIA sidescan sonar system. This scarp represents the removal of more than 1,500 m{sup 3} of Tertiary Arecibo basin strata. The head of the scarp coincides with the location of a fault zone observed on nearby seismicreflection profiles. Interpretation of the GLORIA imagery, and a review of available bathymetric, geophysical, and stratigraphic data and tectonicframework models suggest that the scarp formed as a consequencemore» of slope failure induced by tectonic oversteepening of the insular slope. The oversteepening may be a result of the most recent episode of convergence of the Caribbean and North American plates, which began approximately 4 million years ago. The Arecibo basin strata have been tilted approximately 4{degree} to the north and are apparently gravitationally unstable under the present seismic regime. The volume of material involved in this slope failure is comparable to the material displaced in tsunamogenic submarine landslides along the Peru Trench and Hawaiian Ridge. Therefore, if the slope failure north of Puerto Rico was catastrophic, it was large enough to have generated a tsunami that would have flooded the low ground of northern Puerto Rico.«less

MATSUZAKI, JUN; MASUMORI, MASAYA; TANGE, TAKESHI
20060101
• Background and Aims The main stems of trees on forest slopes incline down the slope to various extents that are characteristic of the species. The inclination has been explained as an active response to a horizontally asymmetrical light environment, but the contributing physiological mechanisms are unknown. The present study tested the hypothesis that stem phototropism, gravitropism, or a combination of the two determines the inclination of tree stems on forest slopes. • Methods Cryptomeria japonica, Pinus densiflora, Quercus myrsinaefolia and Q. serrata were studied. Measurements were made of stem inclination of mature trees on forest slopes in uniform plantations of each species, and changes in stem inclination of potted seedlings in response to illumination treatments (unilateral or overhead) and inclination treatments (artificially inclined or erect). Indices of phototropic and gravitropic responsiveness were evaluated for each species, calculated from the change in stem inclination in response to artificial inclination with unilateral or overhead illumination. • Key Results Stem inclination on forest slopes varied significantly among species: Q. serrata inclined most in the downslope direction, C. japonica inclined the least, and P. densiflora and Q. myrsinaefolia were intermediate. The change in stem inclination of seedlings in each treatment varied significantly among species. Oneyearold stems of Q. serrata and 2yearold stems of Q. myrsinaefolia bent toward the light source. Interspecific variation in the change in stem inclination in response to the unilateral illumination or that in the index of phototropic responsiveness was strongly correlated with the variation in stem inclination on forest slopes. • Conclusions The orientation of woody stems that have finished elongation can be actively controlled by phototropism. Interspecific variation in phototropic responsiveness of trees is a possible significant determinant of interspecific

NASA Astrophysics Data System (ADS)
Zhang, Ke; Cao, Ping; Ma, Guowei; Fan, Wenchen; Meng, Jingjing; Li, Kaihui
20160701
Using the Chengmenshan Copper Mine as a case study, a new methodology for open pit slope design in karstprone ground conditions is presented based on integrated stochasticlimit equilibrium analysis. The numerical modeling and optimization design procedure contain a collection of drill core data, karst cave stochastic model generation, SLIDE simulation and bisection method optimization. Borehole investigations are performed, and the statistical result shows that the length of the karst cave fits a negative exponential distribution model, but the length of carbonatite does not exactly follow any standard distribution. The inverse transform method and acceptancerejection method are used to reproduce the length of the karst cave and carbonatite, respectively. A code for karst cave stochastic model generation, named KCSMG, is developed. The stability of the rock slope with the karst cave stochastic model is analyzed by combining the KCSMG code and the SLIDE program. This approach is then applied to study the effect of the karst cave on the stability of the open pit slope, and a procedure to optimize the open pit slope angle is presented.

Potential Risk Assessment of Mountain Torrent Disasters on Sloping Fields in China
NASA Astrophysics Data System (ADS)
GAO, X.
20171201
China's sloping fields have the problems of low production and serious soil erosion, and mountain torrent disasters will bring more serious soil and water loss to traditional extensive exploitation of sloping field resources. In this paper, China's sloping fields were classified into three grades, such as slightly steep, steep and very steep grade. According to the geological hazards prevention and control regulation, the historical data of China's mountain torrent disasters were spatially interpolated and divided into five classes, such as extremely low, low, middle, high and extremely high level. And the risk level map of mountain torrents was finished in ArcGIS. By using overlaying analysis on sloping fields and risk level map, the potential risk regionalization map of sloping fields in various slope grades was obtained finally. The results shows that the very steep and steep sloping fields are mainly distributed in the first or second stage terraces in China. With the increase of hazard risk level, the area of sloping fields decreases rapidly and the sloping fields in extremely low and low risk levels of mountain torrents reach 98.9%. With the increase of slope grade, the area of sloping fields in various risk levels also declines sharply. The sloping fields take up approximately 60 65% and 26 30% in slightly steep and steep grade areas separately at different risk level. The risk regionalization map can provide effective information for returning farmland to forests or grassland and reducing water and soil erosion of sloping fields in the future.

Bright and Dark Slopes on Ganymede
NASA Technical Reports Server (NTRS)
19970101
Ridges on the edge of Ganymede's north polar cap show bright eastfacing slopes and dark westfacing slopes with troughs of darker material below the larger ridges. North is to the top. The bright slopes may be due to grain size differences, differences in composition between the original surface and the underlying material, frost deposition, or illumination effects. The large 2.4 kilometer (1.5 mile) diameter crater in this image shows frost deposits located on the northfacing rim slope, away from the sun. A smaller 675 meter (2200 foot) diameter crater in the center of the image is surrounded by a bright deposit which may be ejecta from the impact. Ejecta deposits such as this are uncommon for small craters on Ganymede. This image measures 18 by 19 kilometers (11 by 12 miles) and has a resolution of 45 meters (148 feet) per pixel. NASA's Galileo spacecraft obtained this image on September 6, 1996 during its second orbit around Jupiter.
The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at URL http://www.jpl.nasa.gov/galileo/sepo 
ILS Glide Slope Performance Prediction. Volume B
19740901
figures are identical in both volumes. . Abottec A mathematical model for predicting the performance of ILS glide slope arrays in the presence of...irregularities on the performance of ILS Glide Slope antenna systems, a mathematical electromagnetic scattering computer model has been developed. This work was...Antenna ........... 44 9. Test Case Results ..................................... r3 ix PART I. IEO j 1.INTRODUCTION IA mathematical model has been

Desirable plant root traits for protecting unstable slopes against landslides
NASA Astrophysics Data System (ADS)
Stokes, A.; Atger, C.; Bengough, G.; Fourcaud, T.; Sidle, R. C.
20090401
A trait is defined as a distinct, quantitative property of organisms, usually measured at the individual level and used comparatively across species. Plant quantitative traits are extremely important for understanding the local ecology of any site. Plant height, architecture, root depth, wood density, leaf size and leaf nitrogen concentration control ecosystem processes and define habitat for other taxa. An engineer conjecturing as to how plant traits may directly influence physical processes occurring on sloping land just needs to consider how e.g. canopy architecture and litter properties influence the partitioning of rainfall among interception loss, infiltration and runoff. Plant traits not only influence abiotic processes occurring at a site, but also the habitat for animals and invertebrates. Depending on the goal of the landslide engineer, the immediate and longterm effects of plant traits in an environment must be considered if a site is to remain viable and ecologically successful. When vegetation is considered in models of slope stability, usually the only root parameters taken into consideration are tensile strength and root area ratio. Root system spatial structure is not considered, although the length, orientation and diameter of roots are recognized as being of importance. Thick roots act like soil nails on slopes, reinforcing soil in the same way that concrete is reinforced with steel rods. The spatial position of these thick roots also has an indirect effect on soil fixation in that the location of thin and fine roots will depend on the arrangement of thick roots. Thin and fine roots act in tension during failure on slopes and if they cross the slip surface, are largely responsible for reinforcing soil on slopes. Therefore, the most important trait to consider initially is rooting depth. To stabilize a slope against a shallow landslide, roots must cross the shear surface. The number and thickness of roots in this zone will therefore largely

Correlation Between Cometary Gas/Dust Ratios and Heliocentric Distance
NASA Astrophysics Data System (ADS)
Harrington, Olga; Womack, Maria; Lastra, Nathan
20171001
We compiled CObased gas/dust ratios for several comets out to heliocentric distances, rh, of 8 au to probe whether there is a noticeable change in comet behavior over the range that waterice sublimation starts. Previously, gas/dust ratios were calculated for an ensemble of comets using Q(CO2)/efp values derived from infrared measurements, which showed that the gas/dust ratio follows a rh2 within 4 AU, but is flat at greater distances (Bauer et al. 2015). Our project focuses on gas/dust ratios for which CO is assumed to be the dominant gas, in order to test whether similar breaks in slope occur for CO. The gas/dust ratios were calculated from measurements of CO production rates (mostly from millimeterwavelength spectroscopy) and reflected sunlight of comets (mostly via reported visual magnitudes of dusty comets). We present our new CObased gas/dust ratios at different heliocentric distances, compare them to existing CO2based gas/dust ratios, and discuss implications for COdriven and CO2driven activity. We discuss O.H. acknowledges support from the Hartmann Student Travel Grant program. M.W. acknowledges support from NSF grant AST1615917.

Adriatic storm surges and related crossbasin sealevel slope
NASA Astrophysics Data System (ADS)
Međugorac, Iva; Orlić, Mirko; Janeković, Ivica; Pasarić, Zoran; Pasarić, Miroslava
20180501
Storm surges pose a severe threat to the northernmost cities of the Adriatic coast, with Venice being most prone to flooding. It has been noted that some flooding episodes cause significantly different effects along the eastern and western Adriatic coasts, with indications that the difference is related to crossbasin sealevel slope. The present study aims to determine specific atmospheric conditions under which the slope develops and to explore connection with increased sea level along the two coastlines. The analysis is based on sealevel time series recorded at Venice and Bakar over the 19842014 interval, from which 38 most intensive stormsurge episodes were selected, and their meteorological backgrounds (ERAInterim) were studied. The obtained sealevel extremes were grouped into three categories according to their crossbasin sealevel slope: storm surges that slope strongly westward (W type), those that slope eastward (E type) and ordinary storm surges (O type). Results show that the slope is controlled by wind action only, specifically, by the wind component towards a particular coast and by the crossbasin shear of alongbasin wind. Meteorological fields were used to force an oceanographic numerical model in order to confirm the empirically established connection between the atmospheric forcing and the slope. Finally, it has been found that the intensity of storm surges along a particular Adriatic coast is determined by an interplay of sealevel slopes in the along and crossbasin directions.

The performance of different propensity score methods for estimating marginal hazard ratios.
Austin, Peter C
20130720
Propensity score methods are increasingly being used to reduce or minimize the effects of confounding when estimating the effects of treatments, exposures, or interventions when using observational or nonrandomized data. Under the assumption of no unmeasured confounders, previous research has shown that propensity score methods allow for unbiased estimation of linear treatment effects (e.g., differences in means or proportions). However, in biomedical research, timetoevent outcomes occur frequently. There is a paucity of research into the performance of different propensity score methods for estimating the effect of treatment on timetoevent outcomes. Furthermore, propensity score methods allow for the estimation of marginal or populationaverage treatment effects. We conducted an extensive series of Monte Carlo simulations to examine the performance of propensity score matching (1:1 greedy nearestneighbor matching within propensity score calipers), stratification on the propensity score, inverse probability of treatment weighting (IPTW) using the propensity score, and covariate adjustment using the propensity score to estimate marginal hazard ratios. We found that both propensity score matching and IPTW using the propensity score allow for the estimation of marginal hazard ratios with minimal bias. Of these two approaches, IPTW using the propensity score resulted in estimates with lower mean squared error when estimating the effect of treatment in the treated. Stratification on the propensity score and covariate adjustment using the propensity score result in biased estimation of both marginal and conditional hazard ratios. Applied researchers are encouraged to use propensity score matching and IPTW using the propensity score when estimating the relative effect of treatment on timetoevent outcomes. Copyright © 2012 John Wiley & Sons, Ltd.

NASA Technical Reports Server (NTRS)
20040101
This falsecolor image from NASA's Mars Exploration Rover Opportunity panoramic camera shows a downward view from the rover as it sits at the edge of 'Endurance' crater. The gradual, 'blueberry'strewn slope before the rover contains an exposed dark layer of rock that wraps around the upper section of the crater. Scientists suspect that this rock layer will provide clues about Mars' distant past. This mosaic image comprises images taken from 10 rover positions using 750, 530 and 430 nanometer filters, acquired on sol 131 (June 6, 2004). 
Generalized weighted ratio method for accurate turbidity measurement over a wide range.
Liu, Hongbo; Yang, Ping; Song, Hong; Guo, Yilu; Zhan, Shuyue; Huang, Hui; Wang, Hangzhou; Tao, Bangyi; Mu, Quanquan; Xu, Jing; Li, Dejun; Chen, Ying
20151214
Turbidity measurement is important for water quality assessment, food safety, medicine, ocean monitoring, etc. In this paper, a method that accurately estimates the turbidity over a wide range is proposed, where the turbidity of the sample is represented as a weighted ratio of the scattered light intensities at a series of angles. An improvement in the accuracy is achieved by expanding the structure of the ratio function, thus adding more flexibility to the turbidityintensity fitting. Experiments have been carried out with an 850 nm laser and a power meter fixed on a turntable to measure the light intensity at different angles. The results show that the relative estimation error of the proposed method is 0.58% on average for a fourangle intensity combination for all test samples with a turbidity ranging from 160 NTU to 4000 NTU.

QRS slopes for assessment of myocardial damage in chronic chagasic patients
NASA Astrophysics Data System (ADS)
Pueyo, E.; Laciar, E.; Anzuola, E.; Laguna, P.; Jané, R.
20071101
In this study the slopes of the QRS complex are evaluated for determination of the degree of myocardial damage in chronic chagasic patients. Previous studies have demonstrated the ability of the slope indices to reflect alterations in the conduction velocity of the cardiac impulse. Results obtained in the present study show that chronic chagasic patients have significantly flatter QRS slopes as compared to healthy subjects. Not only that but the extent of slope lessening turns out to be proportional to the degree of myocardial damage caused by the disease. Additionally, when incorporating the slope indices into a classification analysis together with other indices indicative of the presence of ventricular late potentials obtained from high resolution electrocardiography, results show that the percentages of correct classification increase up to 62.5%, which means eight points above the percentages obtained prior to incorporation of the slope indices. It can be concluded that QRS slopes have great potential for assessing the degree of severity associated with Chagas' disease.

Slope Stability of Geosynthetic Clay Liner Test Plots
Fourteen fullscale field test plots containing five types of geosynthetic clay liners (GCLs) were constructed on 2H:IV and 3H:IV slopes for the purpose of assessing slope stability. The test plots were designed to simulate typical final cover systems for landfill. Slides occurr...

Ghadiri, H; Ay, M R; Shiran, M B; SoltanianZadeh, H
20130101
Objective: Recently introduced energysensitive Xray CT makes it feasible to discriminate different nanoparticulate contrast materials. The purpose of this work is to present a Kedge ratio method for differentiating multiple simultaneous contrast agents using spectral CT. Methods: The ratio of two images relevant to energy bins straddling the Kedge of the materials is calculated using an analytic CT simulator. In the resulting parametric map, the selected contrast agent regions can be identified using a thresholding algorithm. The Kedge ratio algorithm is applied to spectral images of simulated phantoms to identify and differentiate up to four simultaneous and targeted CT contrast agents. Results: We show that different combinations of simultaneous CT contrast agents can be identified by the proposed Kedge ratio method when energysensitive CT is used. In the Kedge parametric maps, the pixel values for biological tissues and contrast agents reach a maximum of 0.95, whereas for the selected contrast agents, the pixel values are larger than 1.10. The number of contrast agents that can be discriminated is limited owing to photon starvation. For reliable material discrimination, minimum photon counts corresponding to 140 kVp, 100 mAs and 5mm slice thickness must be used. Conclusion: The proposed Kedge ratio method is a straightforward and fast method for identification and discrimination of multiple simultaneous CT contrast agents. Advances in knowledge: A new spectral CTbased algorithm is proposed which provides a new concept of molecular CT imaging by noniteratively identifying multiple contrast agents when they are simultaneously targeting different organs. PMID:23934964
 «
 17
 18
 19
 20
 21
 »
 «
 18
 19
 20
 21
 22
 »

Submarine slope failures due to pipe structure formation.
Elger, Judith; Berndt, Christian; Rüpke, Lars; Krastel, Sebastian; Gross, Felix; Geissler, Wolfram H
20180219
There is a strong spatial correlation between submarine slope failures and the occurrence of gas hydrates. This has been attributed to the dynamic nature of gas hydrate systems and the potential reduction of slope stability due to bottom water warming or sea level drop. However, 30 years of research into this process found no solid supporting evidence. Here we present new reflection seismic data from the Arctic Ocean and numerical modelling results supporting a different link between hydrates and slope stability. Hydrates reduce sediment permeability and cause buildup of overpressure at the base of the gas hydrate stability zone. Resulting hydrofracturing forms pipe structures as pathways for overpressured fluids to migrate upward. Where these pipe structures reach shallow permeable beds, this overpressure transfers laterally and destabilises the slope. This process reconciles the spatial correlation of submarine landslides and gas hydrate, and it is independent of environmental change and water depth.

Cosmogenic 26Al/10Be surface production ratio in Greenland
NASA Astrophysics Data System (ADS)
Corbett, Lee B.; Bierman, Paul R.; Rood, Dylan H.; Caffee, Marc W.; Lifton, Nathaniel A.; Woodruff, Thomas E.
20170201
The assumed value for the cosmogenic 26Al/10Be surface production rate ratio in quartz is an important parameter for studies investigating the burial or subaerial erosion of longlived surfaces and sediments. Recent models and data suggest that the production ratio is spatially variable and may be greater than originally thought. Here we present measured 26Al/10Be ratios for 24 continuously exposed bedrock and boulder surfaces spanning 6177°N in Greenland. Empirical measurements, such as ours, include nuclides produced predominately by neutroninduced spallation with percentlevel contributions by muon interactions. The slope of a York regression line fit to our data is 7.3 ± 0.3 (1σ), suggesting that the 26Al/10Be surface production ratio exceeds the commonly used value of 6.75, at least in the Arctic. A higher 26Al/10Be production ratio has implications for multinuclide cosmogenic isotope studies because it results in greater modeled burial durations and erosion rates.

30 CFR 77.1900  Slopes and shafts; approval of plans.
Code of Federal Regulations, 2010 CFR
20100701
... SAFETY AND HEALTH MANDATORY SAFETY STANDARDS, SURFACE COAL MINES AND SURFACE WORK AREAS OF UNDERGROUND COAL MINES Slope and Shaft Sinking § 77.1900 Slopes and shafts; approval of plans. (a) Each operator of... 30 Mineral Resources 1 20100701 20100701 false Slopes and shafts; approval of plans. 77.1900...

Komiskey, Matthew J.; Stuntebeck, Todd D.; Cox, Amanda L.; Frame, Dennis R.
20130101
The effects of longitudinal slope on the estimation of discharge in a 0.762meter (m) (depth at flume entrance) H flume were tested under controlled conditions with slopes from −8 to +8 percent and discharges from 1.2 to 323 liters per second. Compared to the stagedischarge rating for a longitudinal flume slope of zero, computed discharges were negatively biased (maximum −31 percent) when the flume was sloped downward from the front (entrance) to the back (exit), and positively biased (maximum 44 percent) when the flume was sloped upward. Biases increased with greater flume slopes and with lower discharges. A linear empirical relation was developed to compute a corrected reference stage for a 0.762m H flume using measured stage and flume slope. The reference stage was then used to determine a corrected discharge from the stagedischarge rating. A dimensionally hom*ogeneous correction equation also was developed, which could theoretically be used for all standard Hflume sizes. Use of the corrected discharge computation method for a slopedHflume was determined to have errors ranging from −2.2 to 4.6 percent compared to the Hflume measured discharge at a level position. These results emphasize the importance of the measurement of and the correction for flume slope during an edgeoffield study if the most accurate discharge estimates are desired.

NASA Astrophysics Data System (ADS)
Cameselle, Alejandra L.; Urgeles, Roger; Llopart, Jaume
20140501
level drawdown using slope geotechnical properties and preconditioning factors related to the geological setting of the Valencia Basin. Using several sealevel fall ratios, the variation of the safety factor with respect to successive positions of the sealevel during drawdown has been evaluated.

NASA Astrophysics Data System (ADS)
Edwards, C. S.; Bandfield, J. L.; Christensen, P. R.
20061201
It is possible to obtain surface roughness characteristics, by measuring a single surface from multiple emission angles and azimuths in the thermal infrared. Surfaces will have different temperatures depending on their orientation relative to the sun. A different proportion of sunlit versus shaded surfaces will be in the field of view based on the viewing orientation, resulting in apparent temperature differences. This difference in temperature can be utilized to calculate the slope characteristics for the observed area. This technique can be useful for determining surface slope characteristics not resolvable by orbital imagery. There are two main components to this model, a surface DEM, in this case a synthetic, two dimensional sine wave surface, and a thermal model (provided by H. Kieffer). Using albedo, solar longitude, slope, azimuth, along with several other parameters, the temperature for each cell of the DEM is calculated using the thermal model. A temperature is then predicted using the same observation geometries as the Thermal Emission Spectrometer (TES) observations. A temperature difference is calculated for the two complementary viewing azimuths and emission angles from the DEM. These values are then compared to the observed temperature difference to determine the surface slope. This method has been applied to TES Emission Phase Function (EPF) observations for both the spectrometer and bolometer data, with a footprint size of 10s of kilometers. These specialized types of TES observations measure nearly the same surface from several angles. Accurate surface kinetic temperatures are obtained after the application of an atmospheric correction for the TES bolometer and/or spectrometer. Initial results include an application to the northern circumpolar dunes. An average maximum slope of ~33 degrees has been obtained, which makes physical sense since this is near the angle of repose for sand sized particles. There is some scatter in the data from separate

Winddriven export of Weddell Sea slope water
NASA Astrophysics Data System (ADS)
Meijers, A. J. S.; Meredith, M. P.; Abrahamsen, E. P.; Morales Maqueda, M. A.; Jones, D. C.; Naveira Garabato, A. C.
20161001
The export of waters from the Weddell Gyre to lower latitudes is an integral component of the southern subpolar contribution to the threedimensional oceanic circulation. Here we use more than 20 years of repeat hydrographic data on the continental slope on the northern tip of the Antarctic Peninsula and 5 years of bottom lander data on the slope at 1000 m to show the intermittent presence of a relatively cold, fresh, westward flowing current. This is often bottomintensified between 600 and 2000 dbar with velocities of over 20 cm s1, transporting an average of 1.5 ± 1.5 Sv. By comparison with hydrography on the continental slope within the Weddell Sea and modeled tracer release experiments we show that this slope current is an extension of the Antarctic Slope Current that has crossed the South Scotia Ridge west of Orkney Plateau. On monthly to interannual time scales the density of the slope current is negatively correlated (r > 0.6 with a significance of over 95%) with eastward wind stress over the northern Weddell Sea, but lagging it by 613 months. This relationship holds in both the high temporal resolution bottom lander time series and the 20+ year annual hydrographic occupations and agrees with Weddell Sea export variability observed further east. We compare several alternative hypotheses for this wind stress/export relationship and find that it is most consistent with winddriven acceleration of the gyre boundary current, possibly modulated by eddy dynamics, and represents a mechanism by which climatic perturbations can be rapidly transmitted as fluctuations in the supply of intermediatelevel waters to lower latitudes.

NASA Astrophysics Data System (ADS)
Liu, Gang; Xiao, Hai; Liu, Puling
20170401
Soil aggregates, being a key soil structural unit, influence several soil physical properties such as water infiltration, runoff and erosion. The relationship between soil aggregate stability and interrill and rill erodibility is unclear but critical to processbased erosion prediction models. One obvious reason is that it is hard to distinguish between interrill and rilleroded sediment during the erosion process. This study was designed to partition interrill and rill erosion rates and relates them to the aggregate stability of Ultisols in subtropical China. Six kinds of rare earth element (REE) were applied as tracers mixed with two cultivated soils derived from the Quaternary red clay soil and the shale soil at six slope positions. Soil aggregate stability was determined by the Le Bissonnais (LB)method. Simulated rainfall with three intensities (60, 90 and 120 mm/h) were applied to a soil plot (2.25 m long, 0.5 m wide, 0.2 m deep) at three slope gradients (10°, 20° and 30°) with duration of 30 min after runoff initiation. The results indicated that interrill and rill erosion increased with increasing rainfall intensity and slope gradient for both types of soil. Rill and interrill erosion rates of the shale soil were much higher than those of the Quaternary red clay soil. Rill erosion contribution enhanced with increasing rainfall intensity and slope gradient for both soils. Percentage of the downslope area erosion to total erosion was the largest, followed by the midslope area and then upslope area. Equations using an aggregate stability index As to replace the erodibility factor of interrill and rill erosion in the Water Erosion Prediction Project (WEPP) model were constructed after analyzing the relationships between estimated and measured rill and interrill erosion data. It was shown that these equations based on the stability index, As, have the potential to improve methods for assessing interrill and rill erosion erodibility synchronously for the

A Hybrid Seismic Inversion Method for V P/V S Ratio and Its Application to Gas Identification
NASA Astrophysics Data System (ADS)
Guo, Qiang; Zhang, Hongbing; Han, Feilong; Xiao, Wei; Shang, Zuoping
20180301
The ratio of compressional wave velocity to shear wave velocity (V P/V S ratio) has established itself as one of the most important parameters in identifying gas reservoirs. However, considering that seismic inversion process is highly nonlinear and geological conditions encountered may be complex, a direct estimation of V P/V S ratio from prestack seismic data remains a challenging task. In this paper, we propose a hybrid seismic inversion method to estimate V P/V S ratio directly. In this method, post and prestack inversions are combined in which the prestack inversion for V P/V S ratio is driven by the poststack inversion results (i.e., V P and density). In particular, the V P/V S ratio is considered as a model parameter and is directly inverted from the prestack inversion based on the exact Zoeppritz equation. Moreover, anisotropic Markov random field is employed in order to regularise the inversion process as well as taking care of geological structures (boundaries) information. Aided by the proposed hybrid inversion strategy, the directional weighting coefficients incorporated in the anisotropic Markov random field neighbourhoods are quantitatively calculated by the anisotropic diffusion method. The synthetic test demonstrates the effectiveness of the proposed inversion method. In particular, given low quality of the prestack data and high heterogeneity of the target layers in the field data, the proposed inversion method reveals the detailed model of V P/V S ratio that can successfully identify the gasbearing zones.

Comparison of Three Methods of Assessing Muscle Strength and Imbalance Ratios of the Knee
Moss, Crayton L.; Wright, P. Thomas
19930101
Three strength measurement methods for determining muscle strength and imbalance ratios of the knee were compared in 41 (23 female, 18 male) NCAA Division I track and field athletes. Peak quadriceps extensions and hamstring flexions were measured isotonically, isometrically, and isokinetically. Isokinetic measurements were performed on a Cybex II at 60°/s. Isometric extension and flexion measurements were performed using the Nicholas Manual Muscle Tester (Lafayette Instruments; Lafayette, Ind). Isotonic measurements were done on both Universal and Nautilus apparatuses. Testing order was randomized to avoid a treatment order effect. A repeated measures ANOVA and a post hoc Tukey test were used to compare the three methods of assessing strength and imbalance ratios of the knee. Absolute strength values were significantly different according to gender and mode of testing. Bilateral strength imbalance ratios for knee flexion were significantly lower for the Nautilus leg curl machine. Ipsilateral strength imbalance ratios were significantly greater for the Cybex II. Our results indicated that absolute strength values cannot be interchanged between testing modes. Except for Cybex II (ipsilateral) and Nautilus (bilateral knee flexion), strength imbalance ratios could be interchanged. ImagesFig 1.Fig 2.Fig 3.Fig 4.Fig 5.Fig 6.Fig 7.INGING PMID:16558207

NASA Astrophysics Data System (ADS)
Kunz, Christopher Lee
The midrapidity charged kaon ratios and yields are reported for the 200 AGeV Au+Au, 130 AGeV Au+Au, and 200 GeV pp data sets. The K /K+ ratios are shown to be flat as a function of rapidity, transverse momentum, and centrality for the ranges investigated. The integrated ratios are 0.928 +/ 0.0028 (stat.) +/ 0.03 (sys.), 0.953 +/ 0.0.0012 (stat.) +/ 0.01 (sys.), and 0.964 +/ 0.0039 (stat.) +/ 0.01 (sys.) for 130 AGeV Au+Au, 200 AGeV Au+Au, and 200 GeV pp respectively. Thermal fits are applied to the ratios to extract the baryochemical potential and chemical freezeout temperature. The baryochemical potential, as well as the kaon ratio, suggest that the netbaryon density at midrapidity is approaching zero at RHIC energies. A quark coalescence model suggests quark degrees of freedom are important in the formation of the ratios. The corrected yields are fit with an exponential in mt and the dN/dy and inverse slope parameter are extracted. The inverse slope parameter is used along with the average collective flow velocity in a simple relationship to extract the thermal freezeout temperature. A more sophisticated hydrodynamically motivated fit, using pion, kaon, and proton data, shows agreement with the trend from this simple relationship.

Zhou, Dengwang; Dong, Yongkang; Wang, Benzhang; Jiang, Taofei; Ba, Dexin; Xu, Pengbai; Zhang, Hongying; Lu, Zhiwei; Li, Hui
20170206
We present a slopeassisted BOTDA system based on the vector stimulated Brillouin scattering (SBS) and frequencyagile technique (FAT) for the widestrainrange dynamic measurement. A dimensionless coefficient K defined as the ratio of Brillouin phaseshift to gain is employed to demodulate the strain of the fiber, and it is immune to the power fluctuation of pump pulse and has a linear relation of the frequency detuning for the continuous pump and Stokes waves. For a 30nssquare pump pulse, the available frequency span of the K spectrum can reach up to 200MHz, which is larger than fourfold of 48MHzlinewidth of Brillouin gain spectrum. For a singleslope assisted BOTDA, dynamic strain measurement with the maximum strain of 2467.4με and the vibration frequency components of 10.44Hz and 20.94Hz is obtained. For a multislopeassisted BOTDA, dynamic measurement with the strain variation up to 5372.9με and the vibration frequency components of 5.58Hz and 11.14Hz is achieved by using FAT to extend the strain range.

NASA Astrophysics Data System (ADS)
Zhang, Shengjun; Li, Jiancheng; Jin, Taoyong; Che, Defu
20180401
Marine gravity anomaly derived from satellite altimetry can be computed using either sea surface height or sea surface slope measurements. Here we consider the slope method and evaluate the errors in the slope of the corrections supplied with the Jason1 geodetic mission data. The slope corrections are divided into three groups based on whether they are small, comparable, or large with respect to the 1 microradian error in the current sea surface slope models. (1) The small and thus negligible corrections include dry tropospheric correction, inverted barometer correction, solid earth tide and geocentric pole tide. (2) The moderately important corrections include wet tropospheric correction, dualfrequency ionospheric correction and sea state bias. The radiometer measurements are more preferred than model values in the geophysical data records for constraining wet tropospheric effect owing to the highly variable watervapor structure in atmosphere. The items of dualfrequency ionospheric correction and sea state bias should better not be directly added to range observations for obtaining sea surface slopes since their inherent errors may cause abnormal sea surface slopes and alongtrack smoothing with uniform distribution weight in certain width is an effective strategy for avoiding introducing extra noises. The slopes calculated from radiometer wet tropospheric corrections, and alongtrack smoothed dualfrequency ionospheric corrections, sea state bias are generally within ±0.5 microradians and no larger than 1 microradians. (3) Ocean tide has the largest influence on obtaining sea surface slopes while most of ocean tide slopes distribute within ±3 microradians. Larger ocean tide slopes mostly occur over marginal and islandsurrounding seas, and extra tidal models with better precision or with extending process (e.g. Gote) are strongly recommended for updating corrections in geophysical data records.

Ground reaction force adaptations during crossslope walking and running.
Damavandi, Mohsen; Dixon, Philippe C; Pearsall, David J
20120201
Though transversely inclined (crosssloped) surfaces are prevalent, our understanding of the biomechanical adaptations required for crossslope locomotion is limited. The purpose of this study was to examine ground reaction forces (GRF) in crosssloped and level walking and running. Nine young adult males walked and ran barefoot along an inclinable walkway in both level (0°) and crossslope (10°) configurations. The magnitude and time of occurrence of selected features of the GRF were extracted from the force plate data. GRF data were collected in level walking and running (LW and LR), inclined walking and running upslope (IWU and IRU), and downslope (IWD and IRD), respectively. The GRF data were then analyzed using repeated measures MANOVA. In the anteroposterior direction, the timing of the peak force values differed across conditions during walking (p=.041), while the magnitude of forces were modified across conditions for running (p=.047). Most significant differences were observed in the mediolateral direction, where generally force values were up to 390% and 530% (p<.001) larger during the crossslope conditions compared to level for walking and running, respectively. The maximum force peak during running occurred earlier at IRU compared to the other conditions (p≤.031). For the normal axis a significant difference was observed in the first maximum force peak during walking (p=.049). The findings of this study showed that compared to level surfaces, functional adaptations are required to maintain forward progression and dynamic stability in stance during crossslope walking and running. Copyright © 2011 Elsevier B.V. All rights reserved.

Is there a distinct continental slope fauna in the Antarctic?
NASA Astrophysics Data System (ADS)
Kaiser, Stefanie; Griffiths, Huw J.; Barnes, David K. A.; Brandão, Simone N.; Brandt, Angelika; O'Brien, Philip E.
20110201
The Antarctic continental slope spans the depths from the shelf break (usually between 500 and 1000 m) to ˜3000 m, is very steep, overlain by 'warm' (22.5 °C) Circumpolar Deep Water (CDW), and life there is poorly studied. This study investigates whether life on Antarctica's continental slope is essentially an extension of the shelf or the abyssal fauna, a transition zone between these or clearly distinct in its own right. Using data from several cruises to the Weddell Sea and Scotia Sea, including the ANDEEP (ANtarctic benthic DEEPsea biodiversity, colonisation history and recent community patterns) IIII, BIOPEARL (BIOdiversity, Phylogeny, Evolution and Adaptive Radiation of Life in Antarctica) 1 and EASIZ (Ecology of the Antarctic Sea Ice Zone) II cruises as well as current databases (SOMBASE, SCARMarBIN), four different taxa were selected (i.e. cheilostome bryozoans, isopod and ostracod crustaceans and echinoid echinoderms) and two areas, the Weddell Sea and the Scotia Sea, to examine faunal composition, richness and affinities. The answer has important ramifications to the link between physical oceanography and ecology, and the potential of the slope to act as a refuge and resupply zone to the shelf during glaciations. Benthic samples were collected using Agassiz trawl, epibenthic sledge and Rauschert sled. By bathymetric definition, these data suggest that despite eurybathy in some of the groups examined and apparent similarity of physical conditions in the Antarctic, the shelf, slope and abyssal faunas were clearly separated in the Weddell Sea. However, no such separation of faunas was apparent in the Scotia Sea (except in echinoids). Using a geomorphological definition of the slope, shelfslopeabyss similarity only changed significantly in the bryozoans. Our results did not support the presence of a hom*ogenous and unique Antarctic slope fauna despite a high number of species being restricted to the slope. However, it remains the case that there may be

Antarctic surface elevation and slope from multimission lidar mapping
NASA Astrophysics Data System (ADS)
Sutterley, T. C.; Velicogna, I.; Neumann, T.; Markus, T.
20171201
We present integrated estimates of surface elevation change and slope for the Antarctic Ice Sheet from a combination of measurements from the Airborne Topographic Mapper (ATM), the Land, Vegetation and Ice Sensor (LVIS) and the Ice Cloud and land Elevation Satellite (ICESat1). This technique is a datadriven approach that calculates elevation differentials on a shotbyshot basis. Our method extends the records of each instrument, increases the overall spatial coverage compared to a single instrument and produces highquality, integrated maps of surface elevation, surface elevation change and slope. We use our estimates of elevation change to assess the current state of major outlet glaciers in the Bellinghausen Sea, Amundsen Sea and Getz regions of West Antarctica (WAIS). In the Amundsen Sea, we find that thinning rates of Pine Island Glacier have decreased after 2011 while thinning rates of Smith and Kohler glaciers have increased unabated.

NASA Astrophysics Data System (ADS)
Szabó, Judit Alexandra; Jakab, Gergely; Szabó, Boglárka
20150401
Soil structure degradation has effect through the soil water balance and nutrient supply on the agricultural potential of an area. The soil erosion process comprises two phases: detachment and transport by water. To study the transport phase nozzle type laboratoryscale rainfall simulator was used with constant 80 mmhr1 intensity on an arable haplic Cambisol. Measuring the aggregate and particle size distribution of the soil loss gives a good approach the erosion process. The primary objective of this study was to examine the sediment concentration, and detect the quality and quantity change of the soil loss during a single precipitation under six treatment combinations (recently tilled and crusty soil surface on two different slope steepness, inland inundation and drought soil conditions). Soil loss were collected continually, and separated per aggregate size fractions with sieves in three rounds during a rain to measure the weights. The particle size distribution was measured with Horiba LA950 particle size analyzer. In general the ratio of the macro aggregates decreases and the ratio of the micro aggregates and clay fraction increases in the sediment with time during the precipitation due to the raindrop impact. Sediment concentration depends on the slope steepness, as from steeper slopes the runoff can transport bigger amount of sediment, but from the tilled surface bigger aggregates were washing down. Micro aggregate fraction is one of the indicators of good soil structure. The degradation of micro aggregates occurs in steeper slopes and the most erosive time period depends on the micromorphology of the surface. And while the aggregate size distribution of the soil loss of the treatments shows high variety of distribution and differs from the original soil, the particle size distribution of each aggregate size fraction shows similar trends except the 50250 µm fraction where the fine sand fraction is dominating instead of the loam. This anomaly may be

NASA Astrophysics Data System (ADS)
Yushkov, A.; Risse, M.; Werner, M.; Krieg, J.
20161201
We present a method to determine the protontohelium ratio in cosmic rays at ultrahigh energies. It makes use of the exponential slope, Λ, of the tail of the Xmax distribution measured by an air shower experiment. The method is quite robust with respect to uncertainties from modeling hadronic interactions and to systematic errors on Xmax and energy, and to the possible presence of primary nuclei heavier than helium. Obtaining the protontohelium ratio with air shower experiments would be a remarkable achievement. To quantify the applicability of a particular masssensitive variable for mass composition analysis despite hadronic uncertainties we introduce as a metric the 'analysis indicator' and find an improved performance of the Λ method compared to other variables currently used in the literature. The fraction of events in the tail of the Xmax distribution can provide additional information on the presence of nuclei heavier than helium in the primary beam.

Uranium and Calcium Isotope Ratio Measurements using the Modified Total Evaporation Method in TIMS
NASA Astrophysics Data System (ADS)
Richter, S.; Kuehn, H.; Berglund, M.; Hennessy, C.
20101201
A new version of the "modified total evaporation" (MTE) method for isotopic analysis by multicollector thermal ionization mass spectrometry (TIMS), with high analytical performance and designed in a more userfriendly and routinely applicable way, is described in detail. It is mainly being used for nuclear safeguards measurements of U and Pu and nuclear metrology, but can readily be applied to other scientific tasks in geochemistry, e.g. for Sr, Nd and Ca, as well. The development of the MTE method was organized in collaboration of several "key nuclear mass spectrometry laboratories", namely the New Brunswick Laboratory (NBL), the Institute for Transuranium Elements (ITU), the Safeguards Analytical Laboratory (now Safeguards Analytical Services, SGAS) of the International Atomic Energy Agency (IAEA) and the Institute for Reference Materials and Measurements (IRMM), with IRMM taking the leading role. The manufacturer of the TRITON TIMS instrument, Thermo Fisher Scientific, integrated this method into the software of the instrument. The development has now reached its goal to become a userfriendly and routinely useable method for uranium isotope ratio measurements with high precision and accuracy. Due to the use of the “total evaporation” (TE) method the measurement of the "major" uranium isotope ratio 235U/238U is routinely being performed with a precision of 0.01% to 0.02%. The use of a (certified) reference material measured under comparable conditions is emphasized to achieve an accuracy at a level of 0.02%  depending on the stated uncertainty of the certified value of the reference material. In contrast to the total evaporation method (TE), in the MTE method the total evaporation sequence is interrupted on a regular basis to allow for correction for background from peak tailing, internal calibration of a secondary electron multiplier (SEM) detector versus the Faraday cups, and ion source refocusing. Therefore, the most significant improvement using the

Robustness for slope stability modelling under deep uncertainty
NASA Astrophysics Data System (ADS)
Almeida, Susana; Holcombe, Liz; Pianosi, Francesca; Wagener, Thorsten
20150401
Landslides can have large negative societal and economic impacts, such as loss of life and damage to infrastructure. However, the ability of slope stability assessment to guide management is limited by high levels of uncertainty in model predictions. Many of these uncertainties cannot be easily quantified, such as those linked to climate change and other future socioeconomic conditions, restricting the usefulness of traditional decision analysis tools. Deep uncertainty can be managed more effectively by developing robust, but not necessarily optimal, policies that are expected to perform adequately under a wide range of future conditions. Robust strategies are particularly valuable when the consequences of taking a wrong decision are high as is often the case of when managing natural hazard risks such as landslides. In our work a physically based numerical model of hydrologically induced slope instability (the Combined Hydrology and Stability Model  CHASM) is applied together with robust decision making to evaluate the most important uncertainties (storm events, groundwater conditions, surface cover, slope geometry, material strata and geotechnical properties) affecting slope stability. Specifically, impacts of climate change on longterm slope stability are incorporated, accounting for the deep uncertainty in future climate projections. Our findings highlight the potential of robust decision making to aid decision support for landslide hazard reduction and risk management under conditions of deep uncertainty.
 «
 18
 19
 20
 21
 22
 »
 «
 19
 20
 21
 22
 23
 »

SLOPE STABILITY EVALUATION AND EQUIPMENT SETBACK DISTANCES FOR BURIAL GROUND EXCAVATIONS
DOE Office of Scientific and Technical Information (OSTI.GOV)
MCSHANE DS
20100325
After 1970 Transuranic (TRU) and suspect TRU waste was buried in the ground with the intention that at some later date the waste would be retrieved and processed into a configuration for long term storage. To retrieve this waste the soil must be removed (excavated). Sloping the bank of the excavation is the method used to keep the excavation from collapsing and to provide protection for workers retrieving the waste. The purpose of this paper is to document the minimum distance (setback) that equipment must stay from the edge of the excavation to maintain a stable slope. This evaluation examinesmore» the equipment setback distance by dividing the equipment into two categories, (1) equipment used for excavation and (2) equipment used for retrieval. The section on excavation equipment will also discuss techniques used for excavation including the process of benching. Calculations 122633C004, 'Slope Stability Analysis' (Attachment A), and 300013C001, 'Crane Stability Analysis' (Attachment B), have been prepared to support this evaluation. As shown in the calculations the soil has the following properties: Unit weight 110 pounds per cubic foot; and Friction Angle (natural angle of repose) 38{sup o} or 1.28 horizontal to 1 vertical. Setback distances are measured from the top edge of the slope to the wheels/tracks of the vehicles and heavy equipment being utilized. The computer program utilized in the calculation uses the center of the wheel or track load for the analysis and this difference is accounted for in this evaluation.«less

Crustal insights from gravity and aeromagnetic analysis: Central North Slope, Alaska
Saltus, R.W.; Potter, C.J.; Phillips, J.D.
20060101
Aeromagnetic and gravity data are processed and interpreted to reveal deep and shallow information about the crustal structure of the central North Slope, Alaska. Regional aeromagnetic anomalies primarily reflect deep crustal features. Regional gravity anomalies are more complex and require detailed analysis. We constrain our geophysical models with seismic data and interpretations along two transects including the TransAlaska Crustal Transect. Combined geophysical analysis reveals a remarkable heterogeneity of the preMississippian basem*nt. In the central North Slope, preMississippian basem*nt consists of two distinct geophysical domains. To the southwest, the basem*nt is dense and highly magnetic; this basem*nt is likely mafic and mechanically strong, possibly acting as a buttress to basem*nt involvement in Brooks Range thrusting. To the northeast, the central North Slope basem*nt consists of lower density, moderately magnetic rocks with several discrete regions (intrusions?) of more magnetic rocks. A conjugate set of geophysical trends, northwestsoutheast and southwestnortheast, may be a factor in the crustal response to tectonic compression in this domain. Highresolution gravity and aeromagnetic data, where available, reflect details of shallow fault and fold structure. The maps and profile models in this report should provide useful guidelines and complementary information for regional structural studies, particularly in combination with detailed seismic reflection interpretations. Future challenges include collection of highresolution gravity and aeromagnetic data for the entire North Slope as well as additional deep crustal information from seismic, drilling, and other complementary methods. Copyrights ?? 2006. The American Association of Petroleum Geologists. All rights reserved.

NASA Astrophysics Data System (ADS)
Ausilia Paparo, Maria; Tinti, Stefano
20150401
The model we introduce is an implementation of the Minimum Lithostatic Deviation (MLD) method, developed by Tinti and Manucci (Tinti and Manucci 2006; 2008), that makes use of the limit equilibrium (LE) theory to estimate the stability of a slope. The main purpose here is to analyse the role of a confined aquifer on the value of the Safety Factor (F), the parameter that in the LE is used to determine if a slope is stable or unstable. The classical LE methods treat unconfined aquifers by including the water pore pressure in the MohrCoulomb failure formula: since the water decreases the friction shear strength, the soil above the sliding surface turns out to be more prone to instability. In case of a confined aquifer, however, due to a presence of impermeable layers, the water is not free to flow into the matrix of the overlying soil. We consider here the assumption of a permeable soil sliding over an impermeable layer, which is an occurrence that is found in several known landslide cases (e.g. Person, 2008; Strout and Tjeltja, 2008; Morgan et al., 2010 for offshore slides; and Palladino and Peck, 1972; Miller and Sias, 1998; Jiao et al. 2005; Paparo et al., 2013 for slopes in proximity of artificial or natural water basins) where clay beds form the potential sliding surface: the water, confined below, pushes along these layers and acts on the sliding body as an external bottom load. We modify the MLD method equations in order to take into account the load due to a confined aquifer and apply the new model to the Vajont case, where many have hypothesised the contribution of a confined aquifer to the failure. Our calculations show that the rain load i) infiltrating directly into the soil body and ii) penetrating into the confined aquifer below the clay layers, in addition with the lowering of the reservoir level, were key factors of destabilization of the Mt Toc flank and caused the disastrous landslide.

NASA Astrophysics Data System (ADS)
Rossabi, Sam; Helmig, Detlev
20180401
Nonmethane hydrocarbons have been used as tracers in research on emissions and atmospheric oxidation chemistry. This research investigates source region mixing ratio trends of the nonmethane hydrocarbons ibutane, nbutane, ipentane, and npentane, and the (i/n) isomeric ratios of these compounds between 2001 and 2015. Data collected at Photochemical Assessment Monitoring Stations, mandated by the U.S. Environmental Protection Agency in ozone nonattainment areas, and data collected at Global Greenhouse Gas Reference Network sites within the National Oceanic and Atmospheric Administration network, and analyzed at the Institute of Arctic and Alpine Research at the University of ColoradoBoulder, were examined. Among all considered species, linear regression analyses on concentration time series had negative slopes at 81% of sites, indicating predominantly declining butane and pentane atmospheric concentrations. Mostly negative slopes (78% of sites) were found for the (i/n) butane and pentane isomeric ratios, including all six and seven statistically significant (i/n) butane and pentane trends, respectively. Over the 15 year investigation period and averaged over all sites, total relative changes were 30 and 45% for the (i/n) ratios of butanes and pentanes, respectively, with a relative increase in the prominence of the nisomers. Most likely causes include changing isomeric ratios in gasoline sector emissions, and increasing influence of oil and natural gas industry emissions. Changes in concentrations and isomeric ratios depend on proximity of contributing emission sources to measurement sites.

NASA Astrophysics Data System (ADS)
Putranto, Dinar Dwi Anugerah; Sarino, Yuono, Agus Lestari
20171101
Soil erosion is a natural process that is influenced by the magnitude of rainfall intensity, land cover, slope, soil type and soil processing system. However, it is often accelerated by human activities, such as improper cultivation of agricultural land, clearing of forest land for mining activities, and changes in topographic area due to use for other purposes such as pile materials, mined pits and so on. The Central Lematang subbasin is part of the Lematang sub basin, at the Musi River Region Unit, South Sumatra Province, in Indonesia, which has a topographic shape with varying types of slope and altitude. The critical condition of Central Lematang sub basin has been at an alarming rate, as more than 47.5% of topographic and land use changes are dominated by coal mining activities and forest encroachment by communities. The method used in predicting erosion is by USPED (Unit Stream Power Erosion and Disposition). This is because the USPED [1] method can predict not only sediment transport but also the value of peeling (detachment) and sediment deposition. From slope analysis result, it is found that the highest erosion potential value is found on slope (815%) and the sediment is carried on a steep slope (1525%). Meanwhile, the high sediment deposition area is found in the waters of 5.226 tons / ha / year, the steeper area of 2.12 tons / ha / year.

NASA Technical Reports Server (NTRS)
Werner, Charles L.; Wegmueller, Urs; Small, David L.; Rosen, Paul A.
19940101
Terrain slopes, which can be measured with Synthetic Aperture Radar (SAR) interferometry either from a height map or from the interferometric phase gradient, were used to calculate the local incidence angle and the correct pixel area. Both are required for correct thematic interpretation of SAR data. The interferometric correlation depends on the pixel area projected on a plane perpendicular to the look vector and requires correction for slope effects. Methods for normalization of the backscatter and interferometric correlation for ERS1 SAR are presented.

The effects of soil suction on shallow slope stability.
DOT National Transportation Integrated Search
20130701
This study investigates the slope failures associated with clayey soils so engineers can better : understand the problem and better predict shallow slope stability, and implement preventive : measures if necessary. This research also examines the mec...

NASA Astrophysics Data System (ADS)
Ivey, M.; Verlinde, J.
20141201
The U.S. Department of Energy (DOE), through its scientific user facility, the Atmospheric Radiation Measurement (ARM) Climate Research Facility, provides scientific infrastructure and data to the international Arctic research community via its research sites located on the North Slope of Alaska. The DOE ARM Program has operated an atmospheric measurement facility in Barrow, Alaska, since 1998. Major upgrades to this facility, including scanning radars, were added in 2010. Facilities and infrastructure to support operations of unmanned aerial systems for science missions in the Arctic and North Slope of Alaska were established at Oliktok Point Alaska in 2013. Tethered instrumented balloons will be used in the near future to make measurements of clouds in the boundary layer including mixedphase clouds. The Atmospheric Radiation Measurement (ARM) Climate Research Facility is implementing "megasites" at the Southern Great Plains and North Slope of Alaska sites. Two workshops were held to gather input from the scientific community on these megasites. The NSA workshop was held September 10 and 11 in the Washington DC area. The workshops included discussions of additional profiling remote sensors, detailed measurements of the landatmosphere interface, aerial operations to link the Barrow and Oliktok sites, unmanned aerial system measurements, and routine large eddy simulation model runs. The "megasites" represent a significant new scientific and infrastructure investment by DOE Office of Science, Office of Biological and Environmental Research. This poster will present information on plans for a North Slope "Megasite" as well as new opportunities for members of the arctic research community to make atmospheric measurements using unmanned aerial systems or tethered balloons in conjunction with the DOE ARM facilities on the North Slope of Alaska.

Slopevelocity equilibrium and evolution of surface roughness on a stony hillslope
NASA Astrophysics Data System (ADS)
Nearing, Mark A.; Polyakov, Viktor O.; Nichols, Mary H.; Hernandez, Mariano; Li, Li; Zhao, Ying; Armendariz, Gerardo
20170601
Slopevelocity equilibrium is hypothesized as a state that evolves naturally over time due to the interaction between overland flow and surface morphology, wherein steeper areas develop a relative increase in physical and hydraulic roughness such that flow velocity is a unique function of overland flow rate independent of slope gradient. This study tests this hypothesis under controlled conditions. Artificial rainfall was applied to 2 m by 6 m plots at 5, 12, and 20 % slope gradients. A series of simulations were made with two replications for each treatment with measurements of runoff rate, velocity, rock cover, and surface roughness. Velocities measured at the end of each experiment were a unique function of discharge rates, independent of slope gradient or rainfall intensity. Physical surface roughness was greater at steeper slopes. The data clearly showed that there was no unique hydraulic coefficient for a given slope, surface condition, or rainfall rate, with hydraulic roughness greater at steeper slopes and lower intensities. This study supports the hypothesis of slopevelocity equilibrium, implying that use of hydraulic equations, such as Chezy and Manning, in hillslopescale runoff models is problematic because the coefficients vary with both slope and rainfall intensity.

NASA Astrophysics Data System (ADS)
Marques, Fernando; Queiroz, Sónia; Gouveia, Luís; Vasconcelos, Manuel
20171201
In Portugal, the modifications introduced in 2008 and 2012 in the National Ecological Reserve law (REN) included the mandatory study of slope instability, including slopes, natural scarps, and sea cliffs, at municipal or regional scale, with the purpose of avoiding the use of hazardous zones with buildings and other structures. The law also indicates specific methods to perform these studies, with different approaches for slope instability, natural scarps and sea cliffs. The methods used to produce the maps required by REN law, with modifications and improvements to the law specified methods, were applied to the 71 km2 territory of Almada County, and included: 1) Slope instability mapping using the statistically based Information Value method validated with the landslide inventory using ROC curves, which provided an AAC=0.964, with the higher susceptibility zones which cover at least 80% of the landslides of the inventory to be included in REN map. The map was object of a generalization process to overcome the inconveniences of the use of a pixel based approach. 2) Natural scarp mapping including setback areas near the top, defined according to the law and setback areas near the toe defined by the application of the shadow angle calibrated with the major rockfalls which occurred in the study area; 3) Sea cliffs mapping including two levels of setback zones near the top, and one setback zone at the cliffs toe, which were based on systematic inventories of cliff failures occurred between 1947 and 2010 in a large scale regional littoral monitoring project. In the paper are described the methods used and the results obtained in this study, which correspond to the final maps of areas to include in REN. The results obtained in this study may be considered as an example of good practice of the municipal authorities in terms of solid, technical and scientifically supported regulation definitions, hazard prevention and safe and sustainable land use management.

A Feature Selection Method Based on Fisher's Discriminant Ratio for Text Sentiment Classification
NASA Astrophysics Data System (ADS)
Wang, Suge; Li, Deyu; Wei, Yingjie; Li, Hongxia
With the rapid growth of ecommerce, product reviews on the Web have become an important information source for customers' decision making when they intend to buy some product. As the reviews are often too many for customers to go through, how to automatically classify them into different sentiment orientation categories (i.e. positive/negative) has become a research problem. In this paper, based on Fisher's discriminant ratio, an effective feature selection method is proposed for product review text sentiment classification. In order to validate the validity of the proposed method, we compared it with other methods respectively based on information gain and mutual information while support vector machine is adopted as the classifier. In this paper, 6 subexperiments are conducted by combining different feature selection methods with 2 kinds of candidate feature sets. Under 1006 review documents of cars, the experimental results indicate that the Fisher's discriminant ratio based on word frequency estimation has the best performance with F value 83.3% while the candidate features are the words which appear in both positive and negative texts.

Are North Slope surface alluvial fans preHolocene relicts?
Reimnitz, Erk; Wolf, Stephen C.
19980101
The surface morphology of the northern slope of the Brooks Range (North Slope) from the Canning River, Alaska, eastward is dominated by a series of large alluvial fans and braided streams floored by coarse alluvium. On the basis of our studies, we conclude that the fans are not prograding now nor have they been prograding at any time during the Holocene. During the latest transgression and the following sealevel highstand, the North Slope depositional environment and climate probably differed greatly from the present ones.

NASA Technical Reports Server (NTRS)
Johnson, D. R.; Uccellini, L. W.
19830101
In connection with the employment of the sigma coordinates introduced by Phillips (1957), problems can arise regarding an accurate finitedifference computation of the pressure gradient force. Over steeply sloped terrain, the calculation of the sigmacoordinate pressure gradient force involves computing the difference between two large terms of opposite sign which results in large truncation error. To reduce the truncation error, several finitedifference methods have been designed and implemented. The present investigation has the objective to provide another method of computing the sigmacoordinate pressure gradient force. Phillips' method is applied for the elimination of a hydrostatic component to a flux formulation. The new technique is compared with four other methods for computing the pressure gradient force. The work is motivated by the desire to use an isentropic and sigmacoordinate hybrid model for experiments designed to study flow near mountainous terrain.

Three Dimensional Underwater Sound Propagation Over Sloping Bottoms
NASA Astrophysics Data System (ADS)
Glegg, Stewart A. L.; Riley, J. M.
This article reviews the work which has been carried out over the past few years on three dimensional underwater sound propagation over sloping bottoms. When sound propagates across a slope three dimensional effects can cause shadow zones and mode cut off effects to occur, which could not be predicted by a two dimensional model. For many years the theory for this type of propagation over realistic ocean floors, which can support both compressional and shear waves, eluded workers in this field. Recently the complete solution for the acoustic field in a "wedge domain with penetrable boundaries" has been developed, and this has allowed for complete understanding of three dimensional bottom interacting sound propagation. These theories have been verified by a series of laboratory scale experiments and excellent agreement has been obtained. However only one full scale ocean experiment has been carried out on three dimensional, bottom interacting, acoustic propagation. This showed significant horizontal refraction of sound propagating across a continental slope and further verifies the importance of bottom slopes on underwater sound propagation.

Geospatial Data Integration for Assessing Landslide Hazard on Engineered Slopes
NASA Astrophysics Data System (ADS)
Miller, P. E.; Mills, J. P.; Barr, S. L.; Birkinshaw, S. J.
20120701
Road and rail networks are essential components of national infrastructures, underpinning the economy, and facilitating the mobility of goods and the human workforce. Earthwork slopes such as cuttings and embankments are primary components, and their reliability is of fundamental importance. However, instability and failure can occur, through processes such as landslides. Monitoring the condition of earthworks is a costly and continuous process for network operators, and currently, geospatial data is largely underutilised. The research presented here addresses this by combining airborne laser scanning and multispectral aerial imagery to develop a methodology for assessing landslide hazard. This is based on the extraction of key slope stability variables from the remotely sensed data. The methodology is implemented through numerical modelling, which is parameterised with the slope stability information, simulated climate conditions, and geotechnical properties. This allows determination of slope stability (expressed through the factor of safety) for a range of simulated scenarios. Regression analysis is then performed in order to develop a functional model relating slope stability to the input variables. The remotely sensed raster datasets are robustly resampled to twodimensional crosssections to facilitate meaningful interpretation of slope behaviour and mapping of landslide hazard. Results are stored in a geodatabase for spatial analysis within a GIS environment. For a test site located in England, UK, results have shown the utility of the approach in deriving practical hazard assessment information. Outcomes were compared to the network operator's hazard grading data, and show general agreement. The utility of the slope information was also assessed with respect to autopopulation of slope geometry, and found to deliver significant improvements over the network operator's existing fieldbased approaches.

Flock sizes and sex ratios of canvasbacks in Chesapeake Bay and North Carolina
Haramis, G.M.; Derleth, E.L.; Link, W.A.
19940101
Knowledge of the distribution, size, and sex ratios of flocks of wintering canvasbacks (Aythya valisineria) is fundamental to understanding the species' winter ecology and providing guidelines for management. Consequently, in winter 198687, we conducted 4 monthly aerial photographic surveys to investigate temporal changes in distribution, size, and sex ratios of canvasback flocks in traditional wintering areas of Chesapeake Bay and coastal North Carolina. Surveys yielded 35mm imagery of 194,664 canvasbacks in 842 flocks. Models revealed monthly patterns of flock size in North Carolina and Virginia, but no pattern of change in Maryland. A stepwise analysis of flock size and sex ratio fit a common positive slope (increasing proportion male) for all statemonth datasets, except for North Carolina in February where the slope was larger (P lt 0.001). State and month effects on intercepts were significant (P lt 0.001) and confirmed a previously identified latitudinal gradient in sex ratio in the survey region. There was no relationship between flock purity (% canvasbacks vs. other species) and flock size except in North Carolina in January, February, and March when flock purity was related to flock size. Contrasting characteristics in North Carolina with regard to flock size (larger flocks) and flock purity suggested that proximate factors were reinforcing flocking behavior and possibly species fidelity there. Of possible factors, the need to locate foraging sites within this large, openwater environment was hypothesized to be of primary importance. Comparison of January 1981 and 1987 sex ratios indicated no change in Maryland, but lower (P lt 0.05) canvasback sex ratios (proportion male) in Virginia and North Carolina.

Effects of lava heating on volatilerich slopes on Io
Dundas, Colin M.
20170101
The upper crust of Io may be very rich in volatile sulfur and SO2. The surface is also highly volcanically active, and slopes may be warmed by radiant heat from the lava. This is particularly the case in paterae, which commonly host volcanic eruptions and longlived lava lakes. Paterae slopes are highly variable, but some are greater than 70°. I model the heating of a volatile slope for two endmember cases: instantaneous emplacement of a large sheet flow, and persistent heating by a longlived lava lake. In general, single flows can briefly raise sulfur to the melting temperature, or drive a modest amount of sublimation of SO2. Persistently lavacovered surfaces will drive much more significant geomorphic effects, with potentially significant sublimation and slope retreat. In addition to the direct effects, heating is likely to weaken slope materials and may trigger mass wasting. Thus, if the upper crust of Io is rich in these volatile species, future missions with highresolution imaging are likely to observe actively retreating slopes around lava lakes and other locations of frequent eruptions.

Method for fabricating high aspect ratio structures in perovskite material
Karapetrov, Goran T.; Kwok, WaiKwong; Crabtree, George W.; Iavarone, Maria
20031028
A method of fabricating high aspect ratio ceramic structures in which a selected portion of perovskite or perovskitelike crystalline material is exposed to a high energy ion beam for a time sufficient to cause the crystalline material contacted by the ion beam to have substantially parallel columnar defects. Then selected portions of the material having substantially parallel columnar defects are etched leaving material with and without substantially parallel columnar defects in a predetermined shape having high aspect ratios of not less than 2 to 1. Etching is accomplished by optical or PMMA lithography. There is also disclosed a structure of a ceramic which is superconducting at a temperature in the range of from about 10.degree. K. to about 90.degree. K. with substantially parallel columnar defects in which the smallest lateral dimension of the structure is less than about 5 microns, and the thickness of the structure is greater than 2 times the smallest lateral dimension of the structure.

Highway rock slope management program.
DOT National Transportation Integrated Search
20010630
Development of a comprehensive geotechnical database for risk management of highway rock slope problems is described. Computer software selected to program the client/server application in windows environment, components and structure of the geote...

NASA Astrophysics Data System (ADS)
Schlögel, R.; Marchesini, I.; Alvioli, M.; Reichenbach, P.; Rossi, M.; Malet, J.P.
20180101
We perform landslide susceptibility zonation with slope units using three digital elevation models (DEMs) of varying spatial resolution of the Ubaye Valley (South French Alps). In so doing, we applied a recently developed algorithm automating slope unit delineation, given a number of parameters, in order to optimize simultaneously the partitioning of the terrain and the performance of a logistic regression susceptibility model. The method allowed us to obtain optimal slope units for each available DEM spatial resolution. For each resolution, we studied the susceptibility model performance by analyzing in detail the relevance of the conditioning variables. The analysis is based on landslide morphology data, considering either the whole landslide or only the source area outline as inputs. The procedure allowed us to select the most useful information, in terms of DEM spatial resolution, thematic variables and landslide inventory, in order to obtain the most reliable slope unitbased landslide susceptibility assessment.
 «
 19
 20
 21
 22
 23
 »
 «
 20
 21
 22
 23
 24
 »

NASA Astrophysics Data System (ADS)
Dai, Jun; Zhou, Haigang; Zhao, Shaoquan
20170101
This paper considers a multiscale future hedge strategy that minimizes lower partial moments (LPM). To do this, wavelet analysis is adopted to decompose time series data into different components. Next, different parametric estimation methods with known distributions are applied to calculate the LPM of hedged portfolios, which is the key to determining multiscale hedge ratios over different time scales. Then these parametric methods are compared with the prevailing nonparametric kernel metric method. Empirical results indicate that in the China Securities Index 300 (CSI 300) index futures and spot markets, hedge ratios and hedge efficiency estimated by the nonparametric kernel metric method are inferior to those estimated by parametric hedging model based on the features of sequence distributions. In addition, if minimumLPM is selected as a hedge target, the hedging periods, degree of risk aversion, and target returns can affect the multiscale hedge ratios and hedge efficiency, respectively.

Thermal circulation patterns and turbulent fluxes along steep mountain slopes
NASA Astrophysics Data System (ADS)
Nadeau, D. F.; Pardyjak, E.; Higgins, C. W.; Huwald, H.; Baerenbold, F.; Parlange, M. B.
20101201
In hydrology, it is crucial to understand the atmospheric flow dynamics in mountainous terrain to predict turbulent exchanges of heat and moisture accurately at the regional scale. Under clear sky and weak synoptic conditions, these landatmosphere interactions are driven by thermal circulations that take place over a strong diurnal cycle. During the day, winds travel up the mountain slopes and at night, they travel down toward to the bottom of the valley. Little is known about how the transition between these two regimes takes place over steep slopes. The Slope Experiment at La Fouly (SELF) in the Swiss Alps was designed to investigate these transition periods throughout summer 2010. In this paper, we will present the first results obtained from this field campaign. Data from a network of 16 wireless surface stations is used to define catchment wide micrometeorological processes such as slope and valley wind system development, while detailed measurements of the turbulent processes on a steep idealized slope (20 to 45 degrees) were also made. The slope was instrumented along a transect with four towers (including a surface energy budget station and 10 m tower with sonic anemometers), 13 surface temperature measurement stations and a tethered balloon system to capture the complex interplay between surface and atmosphere. Initial data presented will include basic circulation pattern development and measurements of the turbulent fluxes of water vapor, heat and momentum on the slope.

An energy ratio feature extraction method for optical fiber vibration signal
NASA Astrophysics Data System (ADS)
Sheng, Zhiyong; Zhang, Xinyan; Wang, Yanping; Hou, Weiming; Yang, Dan
20180301
The intrusion events in the optical fiber prewarning system (OFPS) are divided into two types which are harmful intrusion event and harmless interference event. At present, the signal feature extraction methods of these two types of events are usually designed from the view of the time domain. However, the differences of timedomain characteristics for different harmful intrusion events are not obvious, which cannot reflect the diversity of them in detail. We find that the spectrum distribution of different intrusion signals has obvious differences. For this reason, the intrusion signal is transformed into the frequency domain. In this paper, an energy ratio feature extraction method of harmful intrusion event is drawn on. Firstly, the intrusion signals are preprocessed and the power spectral density (PSD) is calculated. Then, the energy ratio of different frequency bands is calculated, and the corresponding feature vector of each type of intrusion event is further formed. The linear discriminant analysis (LDA) classifier is used to identify the harmful intrusion events in the paper. Experimental results show that the algorithm improves the recognition rate of the intrusion signal, and further verifies the feasibility and validity of the algorithm.

Zhang, Y; Yatsuya, H; Li, Y; Chiang, C; Hirakawa, Y; Kawazoe, N; Tamakoshi, K; Toyoshima, H; Aoyama, A
20170101
Objective: This study aims to investigate the association of longterm weightchange slopes, weight fluctuation and the risk of type 2 diabetes mellitus (T2DM) in middleaged Japanese men and women. Methods: A total of 4234 participants of Aichi Workers' Cohort Study who were aged 35–66 years and free of diabetes in 2002 were followed through 2014. Past body weights at the ages of 20, 25, 30, 40 years, and 5 years before baseline as well as measured body weight at baseline were regressed on the ages. Slope and rootmeansquareerror of the regression line were obtained and used to represent the weight changes and the weight fluctuation, respectively. The associations of the weightchange slopes and the weight fluctuation with incident T2DM were estimated by Cox proportional hazards models. Results: During the median followup of 12.2 years, 400 incident cases of T2DM were documented. After adjustment for baseline overweight and other lifestyle covariates, the weightchange slopes were significantly associated with higher incidence of T2DM (hazard ratio (HR): 1.80, 95% confident interval (CI): 1.17–2.77 for men; and HR: 2.78, 95% CI: 1.07–7.23 for women), while the weight fluctuation was not (HR: 1.08, 95% CI: 1.00–1.18 for men and HR: 1.02, 95% CI: 0.84–1.25 for women). Conclusions: Regardless of the presence of overweight, the longterm weightchange slopes were significantly associated with the increased risk of T2DM; however, the weight fluctuation was not associated with the risk of T2DM in middleaged Japanese men and women. PMID:28319107

Directionaware Slope Limiter for 3D Cubic Grids with Adaptive Mesh Refinement
Velechovsky, Jan; Francois, Marianne M.; Masser, Thomas
20180607
In the context of finite volume methods for hyperbolic systems of conservation laws, slope limiters are an effective way to suppress creation of unphysical local extrema and/or oscillations near discontinuities. We investigate properties of these limiters as applied to piecewise linear reconstructions of conservative fluid quantities in threedimensional simulations. In particular, we are interested in linear reconstructions on Cartesian adaptively refined meshes, where a reconstructed fluid quantity at a face center depends on more than a single gradient component of the quantity. We design a new slope limiter, which combines the robustness of a minmod limiter with the accuracy ofmore» a van Leer limiter. The limiter is called DirectionAware Limiter (DAL), because the combination is based on a principal flow direction. In particular, DAL is useful in situations where the Barth–Jespersen limiter for general meshes fails to maintain global linear functions, such as on cubic computational meshes with stencils including only faceneighboring cells. Here, we verify the new slope limiter on a suite of standard hydrodynamic test problems on Cartesian adaptively refined meshes. Lastly, we demonstrate reduced mesh imprinting; for radially symmetric problems such as the Sedov blast wave or the Noh implosion test cases, the results with DAL show better preservation of radial symmetry compared to the other standard methods on Cartesian meshes.«less

Directionaware Slope Limiter for 3D Cubic Grids with Adaptive Mesh Refinement
DOE Office of Scientific and Technical Information (OSTI.GOV)
Velechovsky, Jan; Francois, Marianne M.; Masser, Thomas
In the context of finite volume methods for hyperbolic systems of conservation laws, slope limiters are an effective way to suppress creation of unphysical local extrema and/or oscillations near discontinuities. We investigate properties of these limiters as applied to piecewise linear reconstructions of conservative fluid quantities in threedimensional simulations. In particular, we are interested in linear reconstructions on Cartesian adaptively refined meshes, where a reconstructed fluid quantity at a face center depends on more than a single gradient component of the quantity. We design a new slope limiter, which combines the robustness of a minmod limiter with the accuracy ofmore» a van Leer limiter. The limiter is called DirectionAware Limiter (DAL), because the combination is based on a principal flow direction. In particular, DAL is useful in situations where the Barth–Jespersen limiter for general meshes fails to maintain global linear functions, such as on cubic computational meshes with stencils including only faceneighboring cells. Here, we verify the new slope limiter on a suite of standard hydrodynamic test problems on Cartesian adaptively refined meshes. Lastly, we demonstrate reduced mesh imprinting; for radially symmetric problems such as the Sedov blast wave or the Noh implosion test cases, the results with DAL show better preservation of radial symmetry compared to the other standard methods on Cartesian meshes.«less

Zhang, Shangjian; Wang, Heng; Zou, Xinhai; Zhang, Yali; Lu, Rongguo; Liu, Yong
20150615
An extinctionratioindependent electrical method is proposed for measuring chirp parameters of MachZehnder electricoptic intensity modulators based on frequencyshifted optical heterodyne. The method utilizes the electrical spectrum analysis of the heterodyne products between the intensity modulated optical signal and the frequencyshifted optical carrier, and achieves the intrinsic chirp parameters measurement at microwave region with highfrequency resolution and widefrequency range for the MachZehnder modulator with a finite extinction ratio. Moreover, the proposed method avoids calibrating the responsivity fluctuation of the photodiode in spite of the involved photodetection. Chirp parameters as a function of modulation frequency are experimentally measured and compared to those with the conventional optical spectrum analysis method. Our method enables an extinctionratioindependent and calibrationfree electrical measurement of MachZehnder intensity modulators by using the highresolution frequencyshifted heterodyne technique.

PARTIAL RESTRAINING FORCE INTRODUCTION METHOD FOR DESIGNING CONSTRUCTION COUNTERMESURE ON ΔB METHOD
NASA Astrophysics Data System (ADS)
Nishiyama, Taku; Imanishi, Hajime; Chiba, Noriyuki; Ito, Takao
Landslide or slope failure is a threedimensional movement phenomenon, thus a threedimensional treatment makes it easier to understand stability. The ΔB method (simplified threedimensional slope stability analysis method) is based on the limit equilibrium method and equals to an approximate threedimensional slope stability analysis that extends twodimensional crosssection stability analysis results to assess stability. This analysis can be conducted using conventional spreadsheets or twodimensional slope stability computational software. This paper describes the concept of the partial restraining force introduction method for designing construction countermeasures using the distribution of the restraining force found along survey lines, which is based on the distribution of survey line safety factors derived from the abovestated analysis. This paper also presents the transverse distributive method of restraining force used for planning ground stabilizing on the basis of the example analysis.

Tidally induced residual current over the Malin Sea continental slope
NASA Astrophysics Data System (ADS)
Stashchuk, Nataliya; Vlasenko, Vasiliy; Hosegood, Phil; NimmoSmith, W. Alex M.
20170501
Tidally induced residual currents generated over shelfslope topography are investigated analytically and numerically using the Massachusetts Institute of Technology general circulation model. Observational support for the presence of such a slope current was recorded over the Malin Sea continental slope during the 88th cruise of the RRS ;James Cook; in July 2013. A simple analytical formula developed here in the framework of timeaveraged shallow water equations has been validated against a fully nonlinear nonhydrostatic numerical solution. A good agreement between analytical and numerical solutions is found for a wide range of input parameters of the tidal flow and bottom topography. In application to the Malin Shelf area both the numerical model and analytical solution predicted a northward moving current confined to the slope with its core located above the 400 m isobath and with vertically averaged maximum velocities up to 8 cm s1, which is consistent with the insitu data recorded at three moorings and along crossslope transects.

Slope gradient and shape effects on soil profiles in the northern mountainous forests of Iran
NASA Astrophysics Data System (ADS)
Fazlollahi Mohammadi, M.; Jalali, S. G. H.; Kooch, Y.; SaidPullicino, D.
20161201
In order to evaluate the variability of the soil profiles at two shapes (concave and convex) and five positions (summit, shoulder, back slope, footslope and toeslope) of a slope, a study of a virgin area was made in a Beech stand of mountain forests, northern Iran. Across the slope positions, the soil profiles demonstrated significant changes due to topography for two shape slopes. The solum depth of the convex slope was higher than the concave one in all five positions, and it decreased from the summit to shoulder and increased from the mid to lower slope positions for both convex and concave slopes. The thin solum at the upper positions and concave slope demonstrated that pedogenetic development is least at upper slope positions and concave slope where leaching and biomass productivity are less than at lower slopes and concave slope. A large decrease in the thickness of O and A horizons from the summit to back slope was noted for both concave and convex slopes, but it increased from back slope toward down slope for both of them. The average thickness of B horizons increased from summit to down slopes in the case of the concave slope, but in the case of convex slope it decreased from summit to shoulder and afterwards it increased to the down slope. The thicknesses of the different horizons varied in part in the different positions and shape slopes because they had different plant species cover and soil features, which were related to topography.

NASA Astrophysics Data System (ADS)
Wu, Songbai; Yu, Minghui; Chen, Li
20170201
The slope effect on flow erosivity and soil erosion still remains a controversial issue. This theoretical framework explained and quantified the direct slope effect by coupling the modified GreenAmpt equation accounting for slope effect on infiltration, 1D kinematic wave overland flow routing model, and WEPP soil erosion model. The flow velocity, runoff rate, shear stress, interrill, and rill erosion were calculated on 0°60° isotropic slopes with equal horizontal projective length. The results show that, for shortduration rainfall events, the flow erosivity and erosion amounts exhibit a bellshaped trend which first increase with slope gradient, and then decrease after a critical slope angle. The critical slope angles increase significantly or even vanish with increasing rainfall duration but are nearly independent of the slope projective length. The soil critical shear stress, rainfall intensity, and temporal patterns have great influences on the slope effect trend, while the other soil erosion parameters, soil type, hydraulic conductivity, and antecedent soil moisture have minor impacts. Neglecting the slope effect on infiltration would generate smaller erosion and reduce critical slope angles. The relative slope effect on soil erosion in physically based model WEPP was compared to those in the empirical models USLE and RUSLE. The trends of relative slope effect were found quite different, but the difference may diminish with increasing rainfall duration. Finally, relatively smaller critical slope angles could be obtained with the equal slope length and the range of variation provides a possible explanation for the different critical slope angles reported in previous studies.

NASA Astrophysics Data System (ADS)
Munirwansyah; Irsyam, Masyhur; Munirwan, Reza P.; Yunita, Halida; Zulfan Usrina, M.
20180501
Occupational safety and health (OSH) is a planned effort to prevent accidents and diseases caused by work. In conducting mining activities often occur work accidents caused by unsafe field conditions. In open mine area, there is often a slump due to unstable slopes, which can disrupt the activities and productivity of mining companies. Based on research on stability of open pit slopes conducted by Febrianti [8], the Meureubo coal mine located in Aceh Barat district, on the slope of mine was indicated unsafe slope conditions, it will be continued research on OSH for landslide which is to understand the stability of the excavation slope and the shape of the slope collapse. Plaxis software was used for this research. After analyzing the slope stability and the effect of landslide on OSH with Job Safety Analysis (JSA) method, to identify the hazard to work safety, risk management analysis will be conducted to classified hazard level and its handling technique. This research aim is to know the level of risk of work accident at the company and its prevention effort. The result of risk analysis research is very highrisk value that is > 350 then the activity must be stopped until the risk can be reduced to reach the risk value limit < 20 which is allowed or accepted.

Slope failure investigation management system.
DOT National Transportation Integrated Search
20130301
Highway slopes are exposed to a variety of environmental and climatic conditions, such as deforestation, cycles of : freezing and thawing weather, and heavy storms. Over time, these climatic conditions, in combination with other : factors such as geo...

NASA Astrophysics Data System (ADS)
Kleinbrod, Ulrike; Burjánek, Jan; Hugentobler, Marc; Amann, Florian; Fäh, Donat
20171201
In this study, the seismic response of two slope instabilities is investigated with seismic ambient vibration analysis. Two similar sites have been chosen: an active deepseated slope instability at Cuolm da Vi and the geologically, structurally and morphologically similar, but presently not moving Alp Caschlè slope. Both slopes are located at the upper Vorderrheintal (Canton Graubünden, Switzerland). Ambient vibrations were recorded on both slopes and processed by timefrequency polarization and sitetoreference spectral ratio analysis. The data interpretation shows correlations between degree of disintegration of the rock mass and amplification. However, the ambient vibration analysis conducted, does not allow retrieving a resonance frequency that can be related to the total depth of the instability of Cuolm da Vi. Even though seismic waves can be hardly traced in rock instabilities containing open fractures, it was possible to retrieve a dispersion curve and a velocity profile from the array measurement at Cuolm da Vi due to the high level of disintegration of the rock material down to a depth of about 100 m. From the similar amplification pattern at the two sites, we expect a similar structure, indicating that also the slope at Alp Caschlè was active in the past in a similar manner as Cuolm da Vi. However, a smoother increase of amplification with frequency is observed at Alp Caschlè, which might indicate less disintegration of the rock mass in a particular depth range at this site, when comparing to Cuolm da Vi where a high level of disintegration is observed, resulting from the high activity at the slope. From the frequencydependent amplification, we can distinguish between two parts within both instabilities, one part showing decreasing disintegration of the rock mass with increasing depth, for the other parts lessfractured blocks are observed. Since the block structures are found in the lower part of the instabilities, they might contribute to the

NASA Astrophysics Data System (ADS)
Ashraf Mohamad Ismail, Mohd; Ng, Soon Min; Hazreek Zainal Abidin, Mohd; Madun, Aziman
20180401
The application of geophysical seismic refraction for slope stabilization design using soil nailing method was demonstrated in this study. The potential weak layer of the study area is first identify prior to determining the appropriate length and location of the soil nail. A total of 7 seismic refraction survey lines were conducted at the study area with standard procedures. The refraction data were then analyzed by using the Pickwin and Plotrefa computer software package to obtain the seismic velocity profiles distribution. These results were correlated with the complementary borehole data to interpret the subsurface profile of the study area. It has been identified that layer 1 to 3 is the potential weak zone susceptible to slope failure. Hence, soil nails should be installed to transfer the tensile load from the less stable layer 3 to the more stable layer 4. The soilnail interaction will provide a reinforcing action to the soil mass thereby increasing the stability of the slope.

Peng, Mei; Jaeger, Sara R; Hautus, Michael J
20140301
Psychometric functions are predominately used for estimating detection thresholds in vision and audition. However, the requirement of large data quantities for fitting psychometric functions (>30 replications) reduces their suitability in olfactory studies because olfactory response data are often limited (<4 replications) due to the susceptibility of human olfactory receptors to fatigue and adaptation. This article introduces a new method for fitting individualjudge psychometric functions to olfactory data obtained using the current standard protocolAmerican Society for Testing and Materials (ASTM) E679. The slope parameter of the individualjudge psychometric function is fixed to be the same as that of the group function; the sameshaped symmetrical sigmoid function is fitted only using the intercept. This study evaluated the proposed method by comparing it with 2 available methods. Comparison to conventional psychometric functions (fitted slope and intercept) indicated that the assumption of a fixed slope did not compromise precision of the threshold estimates. No systematic difference was obtained between the proposed method and the ASTM method in terms of group threshold estimates or threshold distributions, but there were changes in the rank, by threshold, of judges in the group. Overall, the fixedslope psychometric function is recommended for obtaining relatively reliable individual threshold estimates when the quantity of data is limited.

AbdelHalim, Lamia M; AbdEl Rahman, Mohamed K; Ramadan, Nesrin K; El Sanabary, Hoda F A; Salem, Maissa Y
20160415
A comparative study was developed between two classical spectrophotometric methods (dual wavelength method and Vierordt's method) and two recent methods manipulating ratio spectra (ratio difference method and first derivative of ratio spectra method) for simultaneous determination of Antazoline hydrochloride (AN) and Tetryzoline hydrochloride (TZ) in their combined pharmaceutical formulation and in the presence of benzalkonium chloride as a preservative without preliminary separation. The dual wavelength method depends on choosing two wavelengths for each drug in a way so that the difference in absorbance at those two wavelengths is zero for the other drug. While Vierordt's method, is based upon measuring the absorbance and the absorptivity values of the two drugs at their λ(max) (248.0 and 219.0 nm for AN and TZ, respectively), followed by substitution in the corresponding Vierordt's equation. Recent methods manipulating ratio spectra depend on either measuring the difference in amplitudes of ratio spectra between 255.5 and 269.5 nm for AN and 220.0 and 273.0 nm for TZ in case of ratio difference method or computing first derivative of the ratio spectra for each drug then measuring the peak amplitude at 250.0 nm for AN and at 224.0 nm for TZ in case of first derivative of ratio spectrophotometry. The specificity of the developed methods was investigated by analyzing different laboratory prepared mixtures of the two drugs. All methods were applied successfully for the determination of the selected drugs in their combined dosage form proving that the classical spectrophotometric methods can still be used successfully in analysis of binary mixture using minimal data manipulation rather than recent methods which require relatively more steps. Furthermore, validation of the proposed methods was performed according to ICH guidelines; accuracy, precision and repeatability are found to be within the acceptable limits. Statistical studies showed that the methods can be

NASA Astrophysics Data System (ADS)
AbdelHalim, Lamia M.; AbdEl Rahman, Mohamed K.; Ramadan, Nesrin K.; EL Sanabary, Hoda F. A.; Salem, Maissa Y.
20160401
A comparative study was developed between two classical spectrophotometric methods (dual wavelength method and Vierordt's method) and two recent methods manipulating ratio spectra (ratio difference method and first derivative of ratio spectra method) for simultaneous determination of Antazoline hydrochloride (AN) and Tetryzoline hydrochloride (TZ) in their combined pharmaceutical formulation and in the presence of benzalkonium chloride as a preservative without preliminary separation. The dual wavelength method depends on choosing two wavelengths for each drug in a way so that the difference in absorbance at those two wavelengths is zero for the other drug. While Vierordt's method, is based upon measuring the absorbance and the absorptivity values of the two drugs at their λmax (248.0 and 219.0 nm for AN and TZ, respectively), followed by substitution in the corresponding Vierordt's equation. Recent methods manipulating ratio spectra depend on either measuring the difference in amplitudes of ratio spectra between 255.5 and 269.5 nm for AN and 220.0 and 273.0 nm for TZ in case of ratio difference method or computing first derivative of the ratio spectra for each drug then measuring the peak amplitude at 250.0 nm for AN and at 224.0 nm for TZ in case of first derivative of ratio spectrophotometry. The specificity of the developed methods was investigated by analyzing different laboratory prepared mixtures of the two drugs. All methods were applied successfully for the determination of the selected drugs in their combined dosage form proving that the classical spectrophotometric methods can still be used successfully in analysis of binary mixture using minimal data manipulation rather than recent methods which require relatively more steps. Furthermore, validation of the proposed methods was performed according to ICH guidelines; accuracy, precision and repeatability are found to be within the acceptable limits. Statistical studies showed that the methods can be

Method for producing thin graphite flakes with large aspect ratios
Bunnell, L. Roy
19930101
A method for making graphite flakes of high aspect ratio by the steps of providing a strong concentrated acid and heating the graphite in the presence of the acid for a time and at a temperature effective to intercalate the acid in the graphite; heating the intercalated graphite at a rate and to a temperature effective to exfoliate the graphite in discrete layers; subjecting the graphite layers to ultrasonic energy, mechanical shear forces, or freezing in an amount effective to separate the layes into discrete flakes.

A study of the surface energy balance on slopes in a tallgrass prairie
NASA Technical Reports Server (NTRS)
Nie, D.; DemetriadesShah, T.; Kanemasu, E. T.
19900101
Four slopes (north, south, east, and west) were selected on the Konza Prairie Research Natural Area to study the effect of topography on surface energy balance and other micrometeorological variables. Energy fluxes, air temperature, and vapor pressure were measured on the sloped throughout the 1988 growing season. Net radiation was the highest on the southfacing slope and lowest on the northfacing slope, and the difference was more than 150 W/sq m (20 to 30 percent) at solar noon. For daily averages, the difference was 25 W/sq m (15 percent) early in the season and increased to 60 W/sq m (30 to 50 percent) in September. The eastfacing and westfacing slopes had the same daily average net radiation, but the time of day when maximum net radiation occurred was one hour earlier for the eastfacing slope and one hour later for the westfacing slope relative to solar noon. Soil heat fluxes were similar for all the slopes. The absolute values of sensible heat flux (h) was consistently lower on the northfacing slope compared with other slopes. Typical difference in the values of H between the northfacing and the southfacing slopes was 15 to 30 W/sq m. The southfacing slope had the greatest day to day fluctuation in latent heat flux as a result of interaction of net radiation, soil moisture, and green leaf area. The northfacing slope had higher air temperatures during the day and higher vapor pressures both during the day and at night when the wind was from the south.
 «
 20
 21
 22
 23
 24
 »
 «
 21
 22
 23
 24
 25
 »

Landscape Evolution Associated with Recurring Slope Lineae (RSL) on Mars
NASA Astrophysics Data System (ADS)
McEwen, A. S.; Dundas, C. M.; Chojnacki, M.; Ojha, L.
20161201
RSL are lowalbedo features that initiate at bedrock outcrops and extend down steep slopes. Individual slopes may have hundreds of lineae, with widths up to 5 m and lengths up to 1.5 km. RSL appear and lengthen gradually or incrementally, fade when inactive, and recur each year, normally in the warmest season. Small channels (120 m wide) are often present and control RSL paths. We have also detected newlyformed topographic land slumps associated with RSL fans in at least 7 locations—4 around a hill in Juventae Chasma, 2 in Garni crater in Melas Chasma, and 1 along wall slopes in Coprates Chasma. This distinctive landform assemblage is seen at several other locations within central and eastern Valles Marineris (VM): Small channels on most slope aspects of isolated hills or crater walls, extending very nearly to the tops of the hills or crater rim, associated with RSL that match the channels in size, and with a set of lobate deposits at the base of RSL fans. RSL activity in VM changes slope aspect with season—Nfacing slopes in northern summer and Sfacing slopes in southern summer. The slumps form midway down the RSL fans, and have a different seasonality—most active from Ls 0120, the coldest time of year in VM. Assuming this association between gullies, RSL, and slumps is not coincidental, an integrated landscape evolution model is needed. Perhaps RSL activity carves the small gullies and deposits sediment near the base of angleofrepose slopes, locally oversteepening the slope, which episodically slumps. RSL activity is seasonal and associated with the transient presence of hydrated salts, which indicates some role for salty water. If the RSL were caused by fluid flow, they should not be precisely confined to angleofrepose or steeper slopes (>28 deg.), so these seem to be dry granular flows whose activity is triggered by or somehow associated with small amounts of water. There are multiple mysteries, such as how the activity recurs at the same

NASA Astrophysics Data System (ADS)
Hagemann, M. W.; Gleason, C. J.; Durand, M. T.
20171101
The forthcoming Surface Water and Ocean Topography (SWOT) NASA satellite mission will measure water surface width, height, and slope of major rivers worldwide. The resulting data could provide an unprecedented account of river discharge at continental scales, but reliable methods need to be identified prior to launch. Here we present a novel algorithm for discharge estimation from only remotely sensed stream width, slope, and height at multiple locations along a massconserved river segment. The algorithm, termed the Bayesian AMHGManning (BAM) algorithm, implements a Bayesian formulation of streamflow uncertainty using a combination of Manning's equation and atmanystations hydraulic geometry (AMHG). Bayesian methods provide a statistically defensible approach to generating discharge estimates in a physically underconstrained system but rely on prior distributions that quantify the a priori uncertainty of unknown quantities including discharge and hydraulic equation parameters. These were obtained from literaturereported values and from a USGS data set of acoustic Doppler current profiler (ADCP) measurements at USGS stream gauges. A data set of simulated widths, slopes, and heights from 19 rivers was used to evaluate the algorithms using a set of performance metrics. Results across the 19 rivers indicate an improvement in performance of BAM over previously tested methods and highlight a path forward in solving discharge estimation using solely satellite remote sensing.

Favourable Changes of the RiskBenefit Ratio in Alpine Skiing
Burtscher, Martin; Ruedl, Gerhard
20150101
During the past five decades recreational alpine skiing has become increasingly safer. The numerous annual media reports on ski injuries have to be interpreted on the basis of the tremendous numbers of skiers. These favourable changes seem primarily be due to the introduction of short carving skis, more rigid and comfortable ski boots, the use of protective gear like helmets, and the optimized preparation of ski slopes. The associated health benefits from skiing, especially arising from its association with a healthier life style, and possibly also from effects related to hypoxia preconditioning and increasing subjective vitality by natural elements clearly outweigh the health hazards. Technical improvements will likely help further reducing the injury risk. At least hypothetically, each individual skier could help to prevent injuries by the development of an appropriate physical fitness and responsible behaviour on ski slopes thereby optimizing the riskbenefit ratio of alpine skiing. PMID:26035659

DESIGN INFORMATION REPORT: PROTECTION OF WASTEWATER LAGOON INTERIOR SLOPES
A problem common to many wastewater treatment and storage lagoons is erosion of the interior slopes. Erosion may be caused by surface runoff and windinduced wave action. The soils that compose the steep interior slopes of lagoons are especially susceptible to erosion and slumpin...

The quadruped robot adaptive control in trotting gait walking on slopes
NASA Astrophysics Data System (ADS)
Zhang, Shulong; Ma, Hongxu; Yang, Yu; Wang, Jian
20171001
The quadruped robot can be decomposed into a planar sevenlink closed kinematic chain in the direction of supporting line and a linear inverted pendulum in normal direction of supporting line. The ground slope can be estimated by using the body attitude information and supporting legs length. The slope degree is used in feedback, to achieve the point of quadruped robot adaptive control walking on slopes. The simulation results verify that the quadruped robot can achieves steady locomotion on the slope with the control strategy proposed in this passage.

The 3D Visualization of Slope Terrain in Sun Moon Lake.
NASA Astrophysics Data System (ADS)
Deng, F.; Gwoshyn, S.; PeiKun, L.
20151201
By doing topographical surveys in a reservoir, we can calculate siltation volume in the period of two measurements. It becomes basic requirement to provide more precise siltation value especially when the differential GPS positioning method and the multibeams echo sounders have been prevailed; however, there are two problems making the result become challenging when doing the siltationsurvey in reservoir. They are both relative with the difficulty in keeping survey accuracy to the area of side slope around the boundary of reservoir. Firstly, the efficiency or accuracy of horizontal positioning using the DGPS may decrease because of the satelliteblocking effect when the surveying ship nears the bank especially in the canyon type of reservoir. Secondly, measurement can only be acquired in the area covered by water using the echo sounder, such that the measuring data of side slope area above water surface are lack to decrease the accuracy or seriously affect the calculation of reservoir water volume. This research is to hold the terrain accuracy when measuring the reservoir side slope and the Sun Moon Lake Reservoir in central Taiwan is chosen as the experimental location. Sun Moon Lake is the most popular place for tourists in Taiwan and also the most important reservoir of the electricity facilities. Furthermore, it owns the biggest pumpedstorage hydroelectricity in Asia. The water in the lake is selfcontained, and its water supply has been input through two underground tunnels, such that a deposit fan is formed when the muds were settled down from the silty water of the ChoShui Shi. Three kinds of survey are conducted in this experiment. First, a closerange photogrammetry, around the border of the Sun Moon Lake is made, or it takes shoots along the bank using a camera linked with a computer running the software Pix4D. The result can provide the DTM data to the side slope above the water level. Second, the bathymetrical data can be obtained by sweeping the

Recurring Lineae on Slopes at Hale Crater, Mars
20150928
Dark, narrow streaks on Martian slopes such as these at Hale Crater are inferred to be formed by seasonal flow of water on contemporary Mars. The streaks are roughly the length of a football field. The imaging and topographical information in this processed, falsecolor view come from the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter. These dark features on the slopes are called "recurring slope lineae" or RSL. Planetary scientists using observations with the Compact Reconnaissance Imaging Spectrometer on the same orbiter detected hydrated salts on these slopes at Hale Crater, corroborating the hypothesis that the streaks are formed by briny liquid water. The image was produced by first creating a 3D computer model (a digital terrain map) of the area based on stereo information from two HiRISE observations, and then draping a falsecolor image over the landshape model. The vertical dimension is exaggerated by a factor of 1.5 compared to horizontal dimensions. The camera records brightness in three wavelength bands: infrared, red and bluegreen. The draped image is one product from HiRISE observation ESP_03070_1440. http://photojournal.jpl.nasa.gov/catalog/PIA19916

Slope basins, headless canyons, and submarine palaeoseismology of the Cascadia accretionary complex
McAdoo, B.G.; Orange, D.L.; Screaton, Elizabeth; Lee, H.; Kayen, R.
19970101
A combination of geomorphological, seismic reflection and geotechnical data constrains this study of sediment erosion and deposition at the toe of the Cascadia accretionary prism. We conducted a series of ALVIN dives in a region south of Astoria Canyon to examine the interrelationship of fluid flow and slope failure in a series of headless submarine canyons. Elevated head gradients at the inflection point of canyons have been inferred to assist in localized failures that feed sediment into a closed slope basin. Measured head gradients are an order of magnitude too low to cause seepageinduced slope failure alone; we therefore propose transient slope failure mechanisms. Intercanyon slopes are uniformly unscarred and smooth, although consolidation tests indicate that up to several metres of material may have been removed. A sheetlike failure would remove sediment uniformly, preserving the observed smooth intercanyon slope. Earthquakeinduced liquefaction is a likely trigger for this type of sheet failure as the slope is too steep and short for sediment flow to organize itself into channels. Bathymetric and seismic reflection data suggest sediment in a trench slope basin between the second and third ridges from the prism's deformation is derived locally. A comparison of the amounts of material removed from the slopes and that in the basin shows that the amount of material removed from the slopes may slightly exceed the amount of material in the basin, implying that a small amount of sediment has escaped the basin, perhaps when the second ridge was too low to form a sufficient dam, or through a gap in the second ridge to the south. Regardless, almost 80% of the material shed off the slopes around the basin is deposited locally, whereas the remaining 20% is redeposited on the incoming section and will be reaccreted.

Zhang, Xing; Wang, Ke Lin; Fu, Zhi Yong; Chen, Hong Song; Zhang, Wei; Shi, Zhi Hua
20170718
The traditional hydrology method, stable hydrogen and oxygen isotope technology, and rainfall simulation method were combined to investigate the hydrological function of small experimental plots (2 m×1.2 m) of contrasting architecture in Northwest Guangxi dolomite area. There were four typical catenary soils along the dolomite peakcluster slope, which were the wholesand, uploam and downsand, the whole loam, upclay and downsand soil types, respectively. All the experimental plots generated little amounts of overland runoff and had a high surface infiltration rate, ranging from 41 to 48 mm·h 1 , and the interflow and deep percolation were the dominant hydrological progress. The interflow was classified into interflow in soil clay A and C according to soil genetic layers. For interflow in soil clay A, matrix flow was generated from the wholesand, uploam and downsand, upclay and downsand soil types, but preferential flow dominated in the wholeloam soil type. As for interflow in soil clay C, preferential flow dominated in the wholeloam, upclay and downsand, uploam and downsand soil types. The soils were shallow yet continuously distributed along the dolomite slope. The difference of hydrological characteristics in soil types with different architectures mainly existed in the runoff generation progress of each interface underground. It proved that the a 3D perspective was needed to study the soil hydrological functions on dolomite slope of Northwest Guangxi, and a new way paying more attention on underground hydrological progress should be explored to fully reveal the nearsurface hydrological processes on karst slope.

Road embankment and slope stabilization.
DOT National Transportation Integrated Search
20100731
This report and the accompanying software are part of efforts to improve the characterization and analysis of pilestabilized : slopes using one or two rows of driven piles. A combination of the limit equilibrium analysis and strain : wedge (SW) model...

Compost for steep slope erosion.
DOT National Transportation Integrated Search
20080601
This study was initiated to develop guidelines for maintenance erosion control measures for steep slopes. The study focused on evaluating and monitoring KY31 fescue germination rates using two media treatments 1) 100 percent by weight compost and 2)...

NASA Astrophysics Data System (ADS)
Rivera, Gustavo; Diamessis, Peter
20161101
The shoaling of an internal solitary wave (ISW) of depression over gentle slopes is explored through fully nonlinear and nonhydrostatic simulations based on a highaccuracy deformed spectral multidomain penalty method. As recently observed in the South China Sea, in highamplitude shoaling ISWs, the alongwave current can exceed the wave celerity resulting in convective instabilities. If the slope is less than 3%, the wave does not disintegrate as in the case of steeper slope shoaling but, instead, maintains its symmetric shape; the above convective instability may drive the formation of a turbulent recirculating core. The sensitivity of convective instabilities in an ISW is examined as a function of the bathymetric slope and wave steepness. ISWs are simulated propagating over both idealized and realistic bathymetry. Emphasis is placed on the structure of the above instabilities, the persistence of trapped cores and their potential for particle entrainment and transport. Additionally, the role of the baroclinic background current on the development of convective instabilities is explored. A preliminary understanding is obtained of the transition to turbulence within a highamplitude ISW shoaling over progressively varying bathymetry.

How to model the stability of terraced slopes? The case study of Tresenda (northern Italy)
NASA Astrophysics Data System (ADS)
Camera, Corrado; Apuani, Tiziana; Masetti, Marco
20150401
Terraces are very common morphological features all around the Mediterranean Basin. They have been built to adapt the natural morphology of the territory to the development of anthropogenic activities, particularly agriculture. However, the increasing land abandonment during the last century is leading to soil degradation and stability issues, mainly due to lack of maintenance of these peculiar environments. The objective of this study was to develop a coupled hydrologicstability model to identify possible triggering areas of superficial landslides during intense rainfall events. The model was tested on a slope uphill of the village of Tresenda, in Northern Italy, which experienced several superficial landslides in the last 35 years. Distributed stability analyses are usually carried out using an infinite slope approach, but in the case of terraces some basic assumptions of this method fail: the parallelism between topographical surface and potential sliding surface and the high ratio between slope length and failure surface depth are the most important examples. In addition, the interest is more on the stability of the terrace system (dry stone retaining wall and backfill soil) and not on soil alone. For these reasons, a stability analysis based on the global method of equilibrium is applied and soft coupled to a well know hydrological model (STARWARS). Sections of terrace, one cell wide, are recognized from the base of a wall to the top of the closest downstream one, and each cell (1 x 1 m2) is considered as a slice. The method of Sarma for circular and noncircular failure is applied. The very fine horizontal resolution (1 m) is crucial to take into consideration the hydrogeological and mechanical properties of dry stone walls (0.61.0 m wide). A sensitivity analysis was conducted for saturated water content, initial volumetric water content, the cohesion and friction angle of soil and walls and soil depth. The results of the sensitivity analysis showed that

Hattori, Shohei; Savarino, Joel; Kamezaki, Kazuki; Ishino, Sakiko; Dyckmans, Jens; Fujinawa, Tamaki; Caillon, Nicolas; Barbero, Albane; Mukotaka, Arata; Toyoda, Sakae; Well, Reinhard; Yoshida, Naohiro
20161230
Triple oxygen and nitrogen isotope ratios in nitrate are powerful tools for assessing atmospheric nitrate formation pathways and their contribution to ecosystems. N 2 O decomposition using microwaveinduced plasma (MIP) has been used only for measurements of oxygen isotopes to date, but it is also possible to measure nitrogen isotopes during the same analytical run. The main improvements to a previous system are (i) an automated distribution system of nitrate to the bacterial medium, (ii) N 2 O separation by gas chromatography before N 2 O decomposition using the MIP, (iii) use of a corundum tube for microwave discharge, and (iv) development of an automated system for isotopic measurements. Three nitrate standards with sample sizes of 60, 80, 100, and 120nmol were measured to investigate the sample size dependence of the isotope measurements. The δ 17 O, δ 18 O, and Δ 17 O values increased with increasing sample size, although the δ 15 N value showed no significant size dependency. Different calibration slopes and intercepts were obtained with different sample amounts. The slopes and intercepts for the regression lines in different sample amounts were dependent on sample size, indicating that the extent of oxygen exchange is also dependent on sample size. The samplesizedependent slopes and intercepts were fitted using natural log (ln) regression curves, and the slopes and intercepts can be estimated to apply to any sample size corrections. When using 100nmol samples, the standard deviations of residuals from the regression lines for this system were 0.5‰, 0.3‰, and 0.1‰, respectively, for the δ 18 O, Δ 17 O, and δ 15 N values, results that are not inferior to those from other systems using gold tube or gold wire. An automated system was developed to measure triple oxygen and nitrogen isotopes in nitrate using N 2 O decomposition by MIP. This system enables us to measure both triple oxygen and nitrogen isotopes in nitrate with comparable precision

Four in vivo gratioweighted imaging methods: Comparability and repeatability at the group level.
Ellerbrock, Isabel; Mohammadi, Siawoosh
20180101
A recent method, denoted in vivo gratioweighted imaging, has related the microscopic gratio, only accessible by ex vivo histology, to noninvasive MRI markers for the fiber volume fraction (FVF) and myelin volume fraction (MVF). Different MRI markers have been proposed for gratio weighted imaging, leaving open the question which combination of imaging markers is optimal. To address this question, the repeatability and comparability of four gratio methods based on different combinations of, respectively, two imaging markers for FVF (tractfiber density, TFD, and neurite orientation dispersion and density imaging, NODDI) and two imaging markers for MVF (magnetization transfer saturation rate, MT, and, from proton density maps, macromolecular tissue volume, MTV) were tested in a scanrescan experiment in two groups. Moreover, it was tested how the repeatability and comparability were affected by two key processing steps, namely the masking of unreliable voxels (e.g., due to partial volume effects) at the group level and the calibration value used to link MRI markers to MVF (and FVF). Our data showed that repeatability and comparability depend largely on the marker for the FVF (NODDI outperformed TFD), and that they were improved by masking. Overall, the gratio method based on NODDI and MT showed the highest repeatability (90%) and lowest variability between groups (3.5%). Finally, our results indicate that the calibration procedure is crucial, for example, calibration to a lower gratio value (g = 0.6) than the commonly used one (g = 0.7) can change not only repeatability and comparability but also the reported dependency on the FVF imaging marker. Hum Brain Mapp 39:2441, 2018. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

NASA Astrophysics Data System (ADS)
Hang, C.; Nadeau, D.; Pardyjak, E.; Parlange, M. B.
20171201
Over the past decades, researchers have made much progress toward a fundamental understanding of the budgets of turbulence variables over flat and hom*ogeneous terrain, and only more recently over complex terrain. However, temperature variance budgets, which are parameterized in most meteorological models, are still poorly understood even under relatively idealized conditions. In this work, we rely on nearsurface turbulence observations collected as part of the Mountain Terrain Atmospheric Modeling and Observations (MATERHORN) program. Data collected in May 2013 in western Utah at three field sites subjected to similar largescale forcing are analyzed: a desert playa (dry lakebed), characterized by a at surface devoid of vegetation; a vegetated site, characterized by at valley oor covered with greasewood vegetation, and a mountain terrain site with a slope angle of 2 4° and covered by highelevation vegetation. The analysis reveals the presence of a 5m layer where the production and dissipation terms of potential temperature variance (θ2) drop rapidly below this level. During convective periods, vertical advection and turbulent transport of θ2 can often be nonnegligible, in particular at Playa and Slope sites. In addition, within the 5m layer, turbulent transport of θ2 acts as a sink term at all sites of interest. Neither the ratio of turbulent transport to production nor the ratio of production to dissipation show a stability dependence during the unstable periods studied. A shortperiod comparison of dissipation rates calculated using dissipationscale resolving hotwire/coldwire anemometry and several common indirect methods using sonic anemometry is presented for data acquired at Playa site. The results indicates that the dissipation rates from all methods follow similar trends, however the magnitudes can differ by a factor of 2  3.

NASA Astrophysics Data System (ADS)
Euser, T.; Luxemburg, W. M. J.; Everson, C. S.; Mengistu, M. G.; Clulow, A. D.; Bastiaanssen, W. G. M.
20140601
The Bowen ratio surface energy balance method is a relatively simple method to determine the latent heat flux and the actual land surface evaporation. The Bowen ratio method is based on the measurement of air temperature and vapour pressure gradients. If these measurements are performed at only two heights, correctness of data becomes critical. In this paper we present the concept of a new measurement method to estimate the Bowen ratio based on vertical dry and wet bulb temperature profiles with high spatial resolution. A short field experiment with distributed temperature sensing (DTS) in a fibre optic cable with 13 measurement points in the vertical was undertaken. A dry and a wetted section of a fibre optic cable were suspended on a 6 m high tower installed over a sugar beet trial plot near Pietermaritzburg (South Africa). Using the DTS cable as a psychrometer, a near continuous observation of vapour pressure and air temperature at 0.20 m intervals was established. These data allowed the computation of the Bowen ratio with a high spatial and temporal precision. The daytime latent and sensible heat fluxes were estimated by combining the Bowen ratio values from the DTSbased system with independent measurements of net radiation and soil heat flux. The sensible heat flux, which is the relevant term to evaluate, derived from the DTSbased Bowen ratio (BRDTS) was compared with that derived from colocated eddy covariance (R2 = 0.91), surface layer scintillometer (R2 = 0.81) and surface renewal (R2 = 0.86) systems. By using multiple measurement points instead of two, more confidence in the derived Bowen ratio values is obtained.

Turbulent properties under sloping Icewall in polar water
NASA Astrophysics Data System (ADS)
Mondal, Mainak; Gayen, Bishakhdatta; Griffiths, Ross W.; Kerr, Ross C.
20171101
Iceshelves around West Antarctic basins are the most vulnerable to melting in the presence of warmer continental shelf water. A large extent of slope exists under these iceshelves, where turbulent transport of salt and heat into the ice wall drives a convective meltwater plume against it. Large scale iceocean models neglect the effect of convection which can lead to a wrong estimation of melt rate. We perform direct numerical simulations under sloping iceshelves with realistic ambient conditions. We estimated the melt rates, boundary layer thicknesses and entrainment coefficients as a function of slope angle. The numerical results are further supported by theoretical predictions. Over the range of slope angles, different mechanisms are active for sustaining turbulence. For near vertical case, buoyancy production is the primary source of turbulent kinetic energy whereas for shallower angles turbulence is produced by velocity shear in the meltwater plume. Australian Research Council.

[Composition and stability of soil aggregates in hedgerowcrop slope land].
Pu, YuLin; Lin, ChaoWen; Xie, DeTi; Wei, ChaoFu; Ni, JiuPai
20130101
Based on a longterm experiment of using hedgerow to control soil and water loss, this paper studied the composition and stability of soil aggregates in a hedgerowcrop slope land. Compared with those under routine contour cropping, the contents of > 0.25 mm soil mechanicalstable and waterstable aggregates under the complex mode hedgerowcrop increased significantly by 13.3%16.1% and 37.8% 55.6%, respectively. Under the complex mode, the contents of > 0.25 mm soil waterstable aggregates on each slope position increased obviously, and the status of > 0.25 mm soil waterstable aggregates being relatively rich at low slope and poor at top slope was improved. Planting hedgerow could significantly increase the mean mass diameter and geometric mean diameter of soil aggregates, decrease the fractal dimension of soil aggregates and the destruction rate of > 0.25 mm soil aggregates, and thus, increase the stability and erosionresistance of soil aggregates in slope cropland. No significant effects of slope and hedgerow types were observed on the composition, stability and distribution of soil aggregates.

Method of determining the optimal dilution ratio for fluorescence fingerprint of food constituents.
Trivittayasil, Vipavee; Tsuta, Mizuki; Kokawa, Mito; Yoshimura, Masatoshi; Sugiyama, Junichi; Fujita, Kaori; Shibata, Mario
20150101
Quantitative determination by fluorescence spectroscopy is possible because of the linear relationship between the intensity of emitted fluorescence and the fluorophore concentration. However, concentration quenching may cause the relationship to become nonlinear, and thus, the optimal dilution ratio has to be determined. In the case of fluorescence fingerprint (FF) measurement, fluorescence is measured under multiple wavelength conditions and a method of determining the optimal dilution ratio for multivariate data such as FFs has not been reported. In this study, the FFs of mixed solutions of tryptophan and epicatechin of different concentrations and composition ratios were measured. Principal component analysis was applied, and the resulting loading plots were found to contain useful information about each constituent. The optimal concentration ranges could be determined by identifying the linear region of the PC score plotted against total concentration.
 «
 21
 22
 23
 24
 25
 »
 «
 21
 22
 23
 24
 25
 »

20090901
channel. More recently, they examined the role of eddies in the overturning circulation of the Southern Ocean using the hemispheric HIM with realistic... meridional velocity with intervals of 0.1 · 10−3ms−1 159 PV equation to study the bayscale circulations : d dt ( f + ζ H0 − f0h0 H 20 ) = F, (4.30) where...200918 DOCTORAL DISSERTATION by Yu Zhang September 2009 Slope/shelf Circulation and Crossslope/shelf Transport Out of a Bay Driven by Eddies from

Chen, Yulong; Irfan, Muhammad; Uchimura, Taro; Zhang, Ke
20180327
Rainfallinduced landslides are one of the most widespread slope instability phenomena posing a serious risk to public safety worldwide so that their temporal prediction is of great interest to establish effective warning systems. The objective of this study is to determine the effectiveness of elastic wave velocities in the surface layer of the slope in monitoring, prediction and early warning of landslide. The smallscale fixed and varied, and largescale slope model tests were conducted. Analysis of the results has established that the elastic wave velocity continuously decreases in response of moisture content and deformation and there was a distinct surge in the decrease rate of wave velocity when failure was initiated. Based on the preliminary results of this analysis, the method using the change in elastic wave velocity proves superior for landslide early warning and suggests that a warning be issued at switch of wave velocity decrease rate.

Slope Error Measurement Tool for Solar Parabolic Trough Collectors: Preprint
DOE Office of Scientific and Technical Information (OSTI.GOV)
Stynes, J. K.; Ihas, B.
20120401
The National Renewable Energy Laboratory (NREL) has developed an optical measurement tool for parabolic solar collectors that measures the combined errors due to absorber misalignment and reflector slope error. The combined absorber alignment and reflector slope errors are measured using a digital camera to photograph the reflected image of the absorber in the collector. Previous work using the image of the reflection of the absorber finds the reflector slope errors from the reflection of the absorber and an independent measurement of the absorber location. The accuracy of the reflector slope error measurement is thus dependent on the accuracy of themore» absorber location measurement. By measuring the combined reflectorabsorber errors, the uncertainty in the absorber location measurement is eliminated. The related performance merit, the intercept factor, depends on the combined effects of the absorber alignment and reflector slope errors. Measuring the combined effect provides a simpler measurement and a more accurate input to the intercept factor estimate. The minimal equipment and setup required for this measurement technique make it ideal for field measurements.«less

Extinction Maps and Dusttogas Ratios in Nearby Galaxies with LEGUS
NASA Astrophysics Data System (ADS)
Kahre, L.; Walterbos, R. A.; Kim, H.; Thilker, D.; Calzetti, D.; Lee, J. C.; Sabbi, E.; Ubeda, L.; Aloisi, A.; Cignoni, M.; Cook, D. O.; Dale, D. A.; Elmegreen, B. G.; Elmegreen, D. M.; Fumagalli, M.; Gallagher, J. S., III; Gouliermis, D. A.; Grasha, K.; Grebel, E. K.; Hunter, D. A.; Sacchi, E.; Smith, L. J.; Tosi, M.; Adamo, A.; Andrews, J. E.; Ashworth, G.; Bright, S. N.; Brown, T. M.; Chandar, R.; Christian, C.; de Mink, S. E.; Dobbs, C.; Evans, A. S.; Herrero, A.; Johnson, K. E.; Kennicutt, R. C.; Krumholz, M. R.; Messa, M.; Nair, P.; Nota, A.; Pellerin, A.; Ryon, J. E.; Schaerer, D.; Shabani, F.; Van Dyk, S. D.; Whitmore, B. C.; Wofford, A.
20180301
We present a study of the dusttogas ratios in five nearby galaxies: NGC 628 (M74), NGC 6503, NGC 7793, UGC 5139 (Holmberg I), and UGC 4305 (Holmberg II). Using Hubble Space Telescope broadband WFC3/UVIS UV and optical images from the Treasury program Legacy ExtraGalactic UV Survey (LEGUS) combined with archival HST/Advanced Camera for Surveys data, we correct thousands of individual stars for extinction across these five galaxies using an isochronematching (reddeningfree Q) method. We generate extinction maps for each galaxy from the individual stellar extinctions using both adaptive and fixed resolution techniques and correlate these maps with neutral H I and CO gas maps from the literature, including the H I Nearby Galaxy Survey and the HERA COLine Extragalactic Survey. We calculate dusttogas ratios and investigate variations in the dusttogas ratio with galaxy metallicity. We find a powerlaw relationship between dusttogas ratio and metallicity, consistent with other studies of dusttogas ratio compared to metallicity. We find a change in the relation when H2 is not included. This implies that underestimation of {N}{{{H}}2} in lowmetallicity dwarfs from a toolow COtoH2 conversion factor X CO could have produced too low a slope in the derived relationship between dusttogas ratio and metallicity. We also compare our extinctions to those derived from fitting the spectral energy distribution (SED) using the Bayesian Extinction and Stellar Tool for NGC 7793 and find systematically lower extinctions from SED fitting as compared to isochrone matching.

Stabilization of erodible slopes with geofibers and nontraditional liquid additives.
DOT National Transportation Integrated Search
20130501
Instability of erodible slopes due to extreme climate events and of permafrost slopes due degradation and thawing is a significant : engineering problem for northern transportation infrastructure. Engineers continually look for mitigation alternative...

NASA Astrophysics Data System (ADS)
Smith, Daniel M.
Geologic hazards affect the lives of millions of people worldwide every year. El Salvador is a country that is regularly affected by natural disasters, including earthquakes, volcanic eruptions and tropical storms. Additionally, rainfallinduced landslides and debris flows are a major threat to the livelihood of thousands. The San Vicente Volcano in central El Salvador has a recurring and destructive pattern of landslides and debris flows occurring on the northern slopes of the volcano. In recent memory there have been at least seven major destructive debris flows on San Vicente volcano. Despite this problem, there has been no known attempt to study the inherent stability of these volcanic slopes and to determine the thresholds of rainfall that might lead to slope instability. This thesis explores this issue and outlines a suggested method for predicting the likelihood of slope instability during intense rainfall events. The material properties obtained from a field campaign and laboratory testing were used for a 2D slope stability analysis on a recent landslide on San Vicente volcano. This analysis confirmed that the surface materials of the volcano are highly permeable and have very low shear strength and provided insight into the groundwater table behavior during a rainstorm. The biggest factors on the stability of the slopes were found to be slope geometry, rainfall totals and initial groundwater table location. Using the results from this analysis a stability chart was created that took into account these main factors and provided an estimate of the stability of a slope in various rainfall scenarios. This chart could be used by local authorities in the event of a known extreme rainfall event to help make decisions regarding possible evacuation. Recommendations are given to improve the methodology for future application in other areas as well as in central El Salvador.

Brooks, G.R.; Holmes, C.W.
19900101
Depositional patterns and sedimentary processes influencing modern southwest Florida carbonate slope development have been identified based upon slope morphology, seismic facies and surface sediment characteristics. Three slopeparallel zones have been identified: (1) an upper slope progradational zone (100500 m) characterized by seawardtrending progradational clinoforms and sediments rich in shelfderived carbonate material, (2) a lower gullied slope zone (500800 m) characterized by numerous gullies formed by the downslope transport of gravity flows, and (3) a baseofslope zone (> 800 m) characterized by thin, lensshaped gravity flow deposits and irregular topography interpreted to be the result of bottom currents and slope failure along the basal extensions of gullies. Modern slope development is interpreted to have been controlled by the offshelf transport of shallowwater material from the adjacent west Florida shelf, deposition of this material along a seaward advancing sediment front, and intermittent bypassing of the lower slope by sediments transported in the form of gravity flows via gullies. Sediments are transported offshelf by a combination of tides and the Loop Current, augmented by the passage of storm frontal systems. Winter storm fronts produce cold, dense, sedimentladen water that cascades offshelf beneath the strong, eastward flowing Florida Current. Sediments are eventually deposited in a relatively low energy transition zone between the Florida Current on the surface and a deep westward flowing counter current. The influence of the Florida Current is evident in the easternmost part of the study area as eastward prograding sediments form a sediment drift that is progressively burying the Pourtales Terrace. The modern southwest Florida slope has seismic reflection and sedimentological characteristics in common with slopes bordering both the nonrimmed west Florida margin and the rimmed platform of the northern Bahamas, and shows many

Godin, JeanPhilippe; Breuillé, Denis; Obled, Christiane; Papet, Isabelle; Schierbeek, Henk; Hopfgartner, Gérard; Fay, LaurentBernard
20081001
Online gas chromatographycombustionisotope ratio mass spectrometry (GCCIRMS) is commonly used to measure isotopic ratios at natural abundance as well as for tracer studies in nutritional and medical research. However, highprecision (13)C isotopic enrichment can also be measured by liquid chromatographyisotope ratio mass spectrometry (LCIRMS). Indeed, LCIRMS can be used, as shown by the new method reported here, to obtain a baseline separation and to measure (13)C isotopic enrichment of underivatised amino acids (Asp, ThrSer, Glu, Pro, Gly, Ala, Cys and Val). In case of Val, at natural abundance, the SD(delta(13)C) reported with this method was found to be below 1 per thousand . Another key feature of the new LCIRMS method reported in this paper is the comparison of the LCIRMS approach with the conventional GCCIRMS determination. To perform this comparative study, isotopic enrichments were measured from underivatised Val and its N(O, S)ethoxycarbonyl ethyl ester derivative. Between 0.0 and 1.0 molar percent excess (MPE) (delta(13)C= 12.3 to 150.8 per thousand), the calculated rootmeansquare (rms) of SD was 0.38 and 0.46 per thousand and the calculated rms of accuracy was 0.023 and 0.005 MPE, respectively, for GCCIRMS and LCIRMS. Both systems measured accurately low isotopic enrichments (0.002 atom percent excess (APE)) with an SD (APE) of 0.0004. To correlate the relative (delta(13)C) and absolute (atom%, APE and MPE) isotopic enrichment of Val measured by the GCCIRMS and LCIRMS devices, mathematical equations showing the slope and intercept of the curves were established and validated with experimental data between 0.0 to 2.3 MPE. Finally, both GCCIRMS and LCIRMS instruments were also used to assess isotopic enrichment of proteinbound (13)CVal in tibial epiphysis in a tracer study performed in rats. Isotopic enrichments measured by LCIRMS and GCCIRMS were not statistically different (p>0.05). The results of this work indicate that

Measurement of Posterior Tibial Slope Using Magnetic Resonance Imaging.
Karimi, Elham; Norouzian, Mohsen; Birjandinejad, Ali; Zandi, Reza; Makhmalbaf, Hadi
20171101
Posterior tibial slope (PTS) is an important factor in the knee joint biomechanics and one of the bone features, which affects knee joint stability. Posterior tibial slope has impact on flexion gap, knee joint stability and posterior femoral rollback that are related to wide range of knee motion. During high tibial osteotomy and total knee arthroplasty (TKA) surgery, proper retaining the mechanical and anatomical axis is important. The aim of this study was to evaluate the value of posterior tibial slope in medial and lateral compartments of tibial plateau and to assess the relationship among the slope with age, gender and other variables of tibial plateau surface. This descriptive study was conducted on 132 healthy knees (80 males and 52 females) with a mean age of 38.26±11.45 (2060 years) at Imam Reza hospital in Mashhad, Iran. All patients, selected and enrolled for MRI in this study, were admitted for knee pain with uncertain clinical history. According to initial physical knee examinations the study subjects were reported healthy. The mean posterior tibial slope was 7.78± 2.48 degrees in the medial compartment and 6.85± 2.24 degrees in lateral compartment. No significant correlation was found between age and gender with posterior tibial slope ( P ≥0.05), but there was significant relationship among PTS with mediolateral width, plateau area and medial plateau. Comparison of different studies revealed that the PTS value in our study is different from other communities, which can be associated with genetic and racial factors. The results of our study are useful to PTS reconstruction in surgeries.

Comparison of slope stability in two Brazilian municipal landfills.
Gharabaghi, B; Singh, M K; Inkratas, C; Fleming, I R; McBean, E
20080101
analysis method is presented in a case study of two Brazilian landfill sites; the Cruz das Almas Landfill in Maceio and the Muribeca Landfill in Recife. The Muribeca site has never recorded a slope failure and is much larger and bettermaintained when compared to the Maceio site at which numerous minor slumps and slides have been observed. Conventional limitequilibrium analysis was used to calculate factors of safety for stability of the landfill side slopes. Results indicate that the Muribeca site is more stable with computed factors of safety values in the range 1.62.4 compared with computed values ranging from 0.9 to 1.4 for the Maceio site at which slope failures have been known to occur. The results suggest that this approach may be useful as a screeninglevel tool when considering the feasibility of implementing LFGTE projects.

NASA Astrophysics Data System (ADS)
Flemings, P. B.
20101201
Integrated Ocean Drilling Program Expepedition 308 used direct measurements of pore pressure, analysis of hydromechanical properties, and geological analysis to illuminate how sedimentation, flow focusing, overpressure, and slope stability couple beneath the seafloor on the deepwater continental slope in the Gulf of Mexico. We used pore pressure penetrometers to measure severe overpressures (60% of the difference between lithostatic stress and hydrostatic pressure) that extend from the seafloor for 100’s of meters. We ran uniaxial consolidation experiments on whole core and found that although permeability is relatively high near the seafloor, the sediments are highly compressible. As a result, the coefficient of consolidation (the hydraulic diffusivity) is remarkably constant over a large range of effective stresses. This behavior accounts for the high overpressure that begins near the seafloor and extends to depth. Forward modeling suggests that flow is driven laterally along a permeable unit called the Blue Unit. Calculations suggest that soon after deposition, lateral flow lowered the effective stress and triggered the submarine landslides that we observe. Later in the evolution of this system, overpressure may have preconditioned the slope to failure by earthquakes. Results from IODP Expedition 308 illustrate how pore pressure and sedimentation control the largescale form of continental margins, how submarine landslides form, and provide strategies for designing stable drilling programs.

Random generation of the turbulence slopes of a ShackHartmann wavefront sensor.
Conan, Rodolphe
20140315
A method to generate the turbulence measurements of a ShackHartmann wavefront sensor is presented. Numerical simulations demonstrate that the spatial and temporal statistic properties of the slopes are respected, allowing us to generate the turbulence wavefront gradient corresponding to both natural and laser guide stars, as well as time series in accordance with the frozen flow model.

Hydro turbine governor’s power control of hydroelectric unit with sloping ceiling tailrace tunnel
NASA Astrophysics Data System (ADS)
Fu, Liang; Wu, Changli; Tang, Weiping
20180201
The primary frequency regulation and load regulation transient process when the hydro turbine governor is under the power mode of hydropower unit with sloping ceiling tailrace are analysed by field test and numerical simulation in this paper. A simulation method based on “threezone model” to simulate small fluctuation transient process of the sloping ceiling tailrace is proposed. The simulation model of hydraulic turbine governor power mode is established by governor’s PLC program identification and parameter measurement, and the simulation model is verified by the test. The slowfastslow “threestage regulation” method which can improve the dynamic quality of hydro turbine governor power mode is proposed. The power regulation strategy and parameters are optimized by numerical simulation, the performance of primary frequency regulation and load regulation transient process when the hydro turbine governor is under power mode are improved significantly.

Statewide analysis of the drainagearea ratio method for 34 streamflow percentile ranges in Texas
Asquith, William H.; Roussel, Meghan C.; Vrabel, Joseph
20060101
The drainagearea ratio method commonly is used to estimate streamflow for sites where no streamflow data are available using data from one or more nearby streamflowgaging stations. The method is intuitive and straightforward to implement and is in widespread use by analysts and managers of surfacewater resources. The method equates the ratio of streamflow at two stream locations to the ratio of the respective drainage areas. In practice, unity often is assumed as the exponent on the drainagearea ratio, and unity also is assumed as a multiplicative bias correction. These two assumptions are evaluated in this investigation through statewide analysis of daily mean streamflow in Texas. The investigation was made by the U.S. Geological Survey in cooperation with the Texas Commission on Environmental Quality. More than 7.8 million values of daily mean streamflow for 712 U.S. Geological Survey streamflowgaging stations in Texas were analyzed. To account for the influence of streamflow probability on the drainagearea ratio method, 34 percentile ranges were considered. The 34 ranges are the 4 quartiles (025, 2550, 5075, and 75100 percent), the 5 intervals of the lower tail of the streamflow distribution (01, 12, 23, 34, and 45 percent), the 20 quintiles of the 4 quartiles (05, 510, 1015, 1520, 2025, 2530, 3035, 3540, 4045, 4550, 5055, 5560, 6065, 6570, 7075, 7580, 8085, 8590, 9095, and 95100 percent), and the 5 intervals of the upper tail of the streamflow distribution (9596, 9697, 9798, 9899 and 99100 percent). For each of the 253,116 (712X711/2) unique pairings of stations and for each of the 34 percentile ranges, the concurrent daily mean streamflow values available for the two stations provided for stationpair application of the drainagearea ratio method. For each station pair, specific statistical summarization (median, mean, and standard deviation) of both the exponent and biascorrection components of the drainagearea ratio

Realistic mass ratio magnetic reconnection simulations with the Multi Level Multi Domain method
NASA Astrophysics Data System (ADS)
Innocenti, Maria Elena; Beck, Arnaud; Lapenta, Giovanni; Markidis, Stefano
20140501
Space physics simulations with the ambition of realistically representing both ion and electron dynamics have to be able to cope with the huge scale separation between the electron and ion parameters while respecting the stability constraints of the numerical method of choice. Explicit Particle In Cell (PIC) simulations with realistic mass ratio are limited in the size of the problems they can tackle by the restrictive stability constraints of the explicit method (Birdsall and Langdon, 2004). Many alternatives are available to reduce such computation costs. Reduced mass ratios can be used, with the caveats highlighted in Bret and Dieckmann (2010). Fully implicit (Chen et al., 2011a; Markidis and Lapenta, 2011) or semi implicit (Vu and Brackbill, 1992; Lapenta et al., 2006; Cohen et al., 1989) methods can bypass the strict stability constraints of explicit PIC codes. Adaptive Mesh Refinement (AMR) techniques (Vay et al., 2004; Fujimoto and Sydora, 2008) can be employed to change locally the simulation resolution. We focus here on the Multi Level Multi Domain (MLMD) method introduced in Innocenti et al. (2013) and Beck et al. (2013). The method combines the advantages of implicit algorithms and adaptivity. Two levels are fully simulated with fields and particles. The so called "refined level" simulates a fraction of the "coarse level" with a resolution RF times bigger than the coarse level resolution, where RF is the Refinement Factor between the levels. This method is particularly suitable for magnetic reconnection simulations (Biskamp, 2005), where the characteristic Ion and Electron Diffusion Regions (IDR and EDR) develop at the ion and electron scales respectively (Daughton et al., 2006). In Innocenti et al. (2013) we showed that basic wave and instability processes are correctly reproduced by MLMD simulations. In Beck et al. (2013) we applied the technique to plasma expansion and magnetic reconnection problems. We showed that notable computational time savings

Large Deformation Analysis of a High Steep Slope Relating to the Laxiwa Reservoir, China
NASA Astrophysics Data System (ADS)
Lin, Peng; Liu, Xiaoli; Hu, Senying; Li, Pujian
20160601
The unstable rock slope in the Laxiwa reservoir area of the Yellow River upstream, China, shows the signs of gravitational and waterimpounding induced large deformations over an area of 1.15 × 105 m2. Slope movements have been measured daily at more than 560 observation points since 2009, when the reservoir was first impounded. At two of these points, an average daily movement of around 6080 mm has ever been observed since the beginning of the impounding. Based on the observed deformations and the geology of the site, a fluidsolid coupling model was then adopted to investigate the existing rockslide activity to better understand the mechanism underlying the large deformations. The results from the field observation, kinematic analysis and numerical modeling indicate that the slope instability is dominated by the strong structurally controlled unstable rock mass. Based on an integrated overview of these analyses, a new toppling mode, i.e. the socalled `conjugate block' mode, is proposed to explain the large deformation mechanism of the slope. The conjugate block is formed by a `dumping block' and toppling blocks. The large deformation of the slope is dominated by (1) a toppling component and (2) a subsiding bilinear wedge induced by planar sliding along the deepseated faults. Following a thorough numerical analysis, it is concluded that small collapses of rock blocks along the slope will be more frequent with the impounding process continuing and the water level fluctuating during the subsequent operation period. Based on a shear strength reduction method and field monitoring, four controlling faults are identified and the instability of the loose structure in the surface layer is analyzed and discussed. The factor of safety against the sliding failure along the deep seated fractures in the slope is 1.72, which reveals that (1) the collapse of the freestanding fractured blocks cannot be ruled out and the volume of the unstable blocks may be greater than 100

Sumida, Keiichi; Molnar, Miklos Z.; Potukuchi, Praveen K.; Thomas, Fridtjof; Lu, Jun L.; Jing, Jennie; Ravel, Vanessa A.; Soohoo, Melissa; Rhee, Connie M.; Streja, Elani; KalantarZadeh, Kamyar; Kovesdy, Csaba P.
20160101
Objective To investigate the association of estimated glomerular filtration rate (eGFR) slopes prior to dialysis initiation with causespecific mortality following dialysis initiation. Patients and Methods In this retrospective cohort study of 18,874 United States veterans who had transitioned to dialysis from October 1, 2007, through September 30, 2011, we examined the association of preendstage renal disease (ESRD) eGFR slopes with allcause, cardiovascular, and infectionrelated mortality during the postESRD period over a median followup of 2.0 years (interquartile range; 1.1–3.2 years). Associations were examined using Cox models with adjustment for potential confounders. Results Prior to transitioning to dialysis, 4,485 (23.8%), 5,633 (29.8%), and 7,942 (42.1%) patients experienced fast, moderate, and slow eGFR decline, respectively, and 814 (4.3%) had increasing eGFR (defined as eGFR slopes of <−10, −10 to <−5, −5 to <0, and ≥0 mL/min/1.73 m2/year). During the study period, a total of 9,744 allcause, 2,702 cardiovascular, and 604 infectionrelated deaths were observed. Compared with patients with slow eGFR decline, those with moderate and fast eGFR decline had a higher risk of allcause (adjusted hazard ratio [HR]: 1.06; 95% confidence interval [CI] 1.00–1.11 and HR: 1.11; 95%CI 1.04–1.18, respectively) and cardiovascular mortality (HR: 1.11; 95%CI 1.01–1.23 and HR: 1.13; 95%CI 1.00–1.27, respectively). In contrast, increasing eGFR was only associated with higher infectionrelated mortality (HR: 1.49; 95%CI 1.03–2.17). Conclusion Rapid eGFR decline is associated with higher allcause and cardiovascular mortality, and increasing eGFR is associated with higher infectionrelated mortality among incident dialysis patients. PMID:26848002

Forecasting slope failures from spacebased synthetic aperture radar (SAR) measurements
NASA Astrophysics Data System (ADS)
Wasowski, J.; Bovenga, F.; Nutricato, R.; Nitti, D. O.; Chiaradia, M. T.; Tijani, K.; Morea, A.
20171201
New spaceborne radar sensors enable multiscale monitoring of potentially unstable slopes thanks to widearea coverage (tens of thousands km2), regular longterm image acquisition schedule with increasing revisit frequency (weekly to daily), and high measurement precision (mm). In particular, the recent radar satellite missions e.g., COSMOSkyMed (CSK), Sentinel1 (S1) and improved multitemporal interferometry (MTI) processing techniques allow timely delivery of information on slow ground surface displacements. Here we use two case study examples to show that it is possible to capture prefailure slope strains through longterm MTIbased monitoring. The first case is a retrospective investigation of a huge 500ML m3 landslide, which occurred in Sept. 2016 in a large, active opencast coal mine in central Europe. We processed over 100 S1 images acquired since Fall 2014. The MTI results showed that the slope that failed had been unstable at least since 2014. Importantly, we detected consistent displacement trends and trend changes, which can be used for slope failure forecasting. Specifically, we documented significant acceleration in slope surface displacement in the two months preceding the catastrophic failure. The second case of retrospectively captured prefailure slope strains regards our earlier study of a small 50 m long landslide, which occurred on Jan. 2014 and caused the derailment of a train on the railway line connecting NW Italy to France. We processed 56 CSK images acquired from Fall 2008 to Spring 2014. The MTI results revealed prefailure displacements of the engineering structures on the slope subsequently affected by the 2014 slide. The analysis of the MTI time series further showed that the displacements had been occurring since 2009. This information could have been used to forewarn the railway authority about the slope instability hazard. The above examples indicate that more frequent and consistent image acquisitions by the new radar

Reed, Shelby D; Stewart, Suzanne Biehn; Scales, Charles D; Moul, Judd W
20140701
The NADiA ProsVue is a prognostic system that measures prostatespecific antigen slope to identify men at lower risk of clinical recurrence of prostate cancer after radical prostatectomy. We developed a decisionmodeling framework to evaluate its costeffectiveness to guide the use of adjuvant radiotherapy (ART). We populated the model using patientlevel data and external sources. Patients were classified as intermediate risk or high risk on the basis of Cancer of the Prostate Risk AssessmentPostsurgical (CAPRAS) nomogram and then stratified by the ProsVue slope (≤2 pg/mL/mo; >2 pg/mL/mo) and receipt of ART. In sensitivity analyses, we varied the effect of the ProsVue slope on the use of ART and other model parameters. The costeffectiveness of the ProsVueguided strategy varied widely because of small differences in qualityadjusted lifeyears (QALYs) at 10 years. In the intermediaterisk group, when the use of ART decreased from 20% (standard care) to 7.5% among patients with a ProsVue slope value of2 pg/mL/mo or less, the incremental costeffectiveness ratio was $25,160/QALY. In the highrisk group, the use of ART would have to decrease from 40% (standard care) to 11.5% among those with a ProsVue slope value of 2 pg/mL/mo or less to obtain a ratio of $50,000/QALY. The costeffectiveness ratios were sensitive to varying benefits of salvage therapy, quality of life, and costs of ART and ProsVue testing. The effect of the ProsVue system on costs will be dependent on the extent to which ART decreases among men identified as having a low risk of recurrence. Its effect on QALYs will remain conditional on uncertain clinical and qualityoflife benefits associated with ART. Copyright © 2014 International Society for Pharmacoeconomics and Outcomes Research (ISPOR). Published by Elsevier Inc. All rights reserved.

Wolbers, Marcel; Babiker, Abdel; Sabin, Caroline; Young, Jim; Dorrucci, Maria; Chêne, Geneviève; Mussini, Cristina; Porter, Kholoud; Bucher, Heiner C.
20100101
Background CD4 cell count is a strong predictor of the subsequent risk of AIDS or death in HIVinfected patients initiating combination antiretroviral therapy (cART). It is not known whether the rate of CD4 cell decline prior to therapy is related to prognosis and should, therefore, influence the decision on when to initiate cART. Methods and Findings We carried out survival analyses of patients from the 23 cohorts of the CASCADE (Concerted Action on SeroConversion to AIDS and Death in Europe) collaboration with a known date of HIV seroconversion and with at least two CD4 measurements prior to initiating cART. For each patient, a precART CD4 slope was estimated using a linear mixed effects model. Our primary outcome was time from initiating cART to a first new AIDS event or death. We included 2,820 treatmentnaïve patients initiating cART with a median (interquartile range) precART CD4 cell decline of 61 (46–81) cells/µl per year; 255 patients subsequently experienced a new AIDS event or death and 125 patients died. In an analysis adjusted for established risk factors, the hazard ratio for AIDS or death was 1.01 (95% confidence interval 0.97–1.04) for each 10 cells/µl per year reduction in precART CD4 cell decline. There was also no association between precART CD4 cell slope and survival. Alternative estimates of CD4 cell slope gave similar results. In 1,731 AIDSfree patients with >350 CD4 cells/µl from the precART era, the rate of CD4 cell decline was also not significantly associated with progression to AIDS or death (hazard ratio 0.99, 95% confidence interval 0.94–1.03, for each 10 cells/µl per year reduction in CD4 cell decline). Conclusions The CD4 cell slope does not improve the prediction of clinical outcome in patients with a CD4 cell count above 350 cells/µl. Knowledge of the current CD4 cell count is sufficient when deciding whether to initiate cART in asymptomatic patients. Please see later in the article for the Editors' Summary PMID
 «
 21
 22
 23
 24
 25
 »
 «
 21
 22
 23
 24
 25
 »

Plant succession on talus slopes in northern Idaho as influenced by slope exposure
R. Daubenmire; A. W. Slipp
19430101
One of the most conspicuous features of the forested regions of northern Idaho is the small treeless areas which occupy portions of the southerly exposures of especially prominent peaks and ridges. These areas, sometimes referred to as parks or balds, begin at the summits of the prominences and extend down over the southfacing slopes sometimes as much as approximately...

NASA Astrophysics Data System (ADS)
Hendrickx, Hanne; Delaloye, Reynald; Nyssen, Jan; Frankl, Amaury
20170401
Climate change is altering temperature regimes and precipitation patterns worldwide. In the European Alps, atmospheric temperatures have risen twice as fast as the global average since 1900, while precipitation regimes are changing as well. Snow cover duration and extent has significantly decreased in the Swiss Alps, mainly due to earlier spring melt and rise in winter temperatures. Moreover, future projections predict a continuation of these trends. Spatial distribution and thermal properties of permafrost are highly influenced by ground surface conditions (snow and vegetation) and air temperature. Climate induced permafrost degradation is, therefore, expected. While alpine permafrost research has mainly focused on rock glaciers, less attention has been given to talus slopes. The latter are subjected to different kinds of slope processes such as debris flows, solifluction, permafrost creep, avalanches and rock fall. These processes are especially effective under a changing periglacial climate. Therefore, it is important to study permafrost distribution in these talus slopes, since it is believed to have large influence on slope stability. In this study, permafrost distribution will be mapped on several talus slope segments (10  40 ha) using geomorphological evidence, temperature data and measuring electrical resistivity tomography (ERT) profiles in addition to already existing data. The current dynamics of the study area will be studied by constructing detailed 3D models, using ground based and aerial photography (Unmanned Aerial Vehicles, UAV) and the StructurefromMotion method (SfM). The resulting Digital Elevation Models (DEM) will be used to quantify and understand the current geomorphological processes acting on these talus slopes. Historical aerial and terrestrial photographs will be used to give an idea about the magnitude and frequency of past geomorphic processes (e.g. debris flows). Historical and current dynamics can then be compared and contrasted

NASA Astrophysics Data System (ADS)
Jinghai, Zhou; Tianbei, Kang; Fengchi, Wang; Xindong, Wang
20171101
Eight less stirrups in the core area frame joints are simulated by ABAQUS finite element numerical software. The composite reinforcement method is strengthened with carbon fiber and increasing column section, the axial compression ratio of reinforced specimens is 0.3, 0.45 and 0.6 respectively. The results of the loaddisplacement curve, ductility and stiffness are analyzed, and it is found that the different axial compression ratio has great influence on the bearing capacity of increasing column section strengthening method, and has little influence on carbon fiber reinforcement method. The different strengthening schemes improve the ultimate bearing capacity and ductility of frame joints in a certain extent, composite reinforcement joints strengthening method to improve the most significant, followed by increasing column section, reinforcement method of carbon fiber reinforced joints to increase the minimum.

Lee, Jonathan K.; Visser, H.M.; Jenter, H.L.; Duff, M.P.
20000101
U.S. Geological Survey (USGS) hydrologists and ecologist are conducting studies to quantify vegetative flow resistance in order to improve numerical models of surfacewater flow in the Florida Everglades. Watersurface slope is perhaps the most difficult of the flow resistance parameters to measure in the Everglades due to the very low gradients of the topography and flow. In an effort to measure these very small slopes, a unique pipe manometer was developed for the local measurement of watersurface slopes on the order of 1 centimeter per kilometer (cm/km). According to theory, a very precise measurement of centerline velocity obtained inside the pipe manometer should serve as a unique proxy for watersurface slope in the direction of the pipe axis. In order to confirm this theoretical relationship and calibrate the pipe manometer, watersurface elevation and pipe centerline velocity data were simultaneously measured in a set of experiments carried out in the tilting flume at the USGS Hydraulic Laboratory Facility at Stennis Space Center, Mississippi. A description of the instrumentation and methods used to evaluate this technique for measuring watersurface slope as well as a summary of the entire data set is presented.

Chen, YanHui; Chen, MingHua; Wang, Guo; Chen, WenXiang; Yang, ShunCheng; Chai, Peng
20101001
The effects of different slopes on nitrogen transport along with runoff from sloping plots amended with sewage sludge on a lateritic red soil were studied under simulated rainfall conditions. When the sludge was broadcasted and mixed with surface soils (BM), the MTN (total nitrogen of mixing sample), STN (total nitrogen of settled sample), TPN (total particulate nitrogen), TSN (total suspended nitrogen), TDN (total dissolved nitrogen) and NH4(+) N concentrations and nitrogen loss amounts in runoff of all treatments were highest at 1 day or 18 days after application. The highest concentrations and the loss amounts of MTN and STN in the slope runoff for the BM treatment increased with slope degree, showing increasing pollution risks to the surface waters. The STN concentration and loss amounts from the 25 degrees plots were 126.1 mg x L(1) and 1788.6 mg x m(2), respectively, being 4.6 times and 5.8 times of the corresponding values from the 10 degrees plots, respectively. Then the concentrations and the loss amounts of nitrogen (except NO3() N) from the BM plots diminished rapidly first and then tended to be stable with dwindling differences between the slopes. The loss of MTN and STN in early runoff (1 day and 18 days) accounted for 68.6% 73.4% and 62.3% 66.7% of the cumulative loss amounts during the experimental period for all the broadcasted treatments. Runoff loss coefficients of MTN increased in the order of 20 degrees > 25 degrees > 15 degrees > 10 degrees. Nitrogen was largely lost in dissolved species while large portion of NH4(+) N was lost with particulates.

Ocean processes at the Antarctic continental slope.
Heywood, Karen J; Schmidtko, Sunke; Heuzé, Céline; Kaiser, Jan; Jickells, Timothy D; Queste, Bastien Y; Stevens, David P; Wadley, Martin; Thompson, Andrew F; Fielding, Sophie; Guihen, Damien; Creed, Elizabeth; Ridley, Jeff K; Smith, Walker
20140713
The Antarctic continental shelves and slopes occupy relatively small areas, but, nevertheless, are important for global climate, biogeochemical cycling and ecosystem functioning. Processes of water mass transformation through sea ice formation/melting and oceanatmosphere interaction are key to the formation of deep and bottom waters as well as determining the heat flux beneath ice shelves. Climate models, however, struggle to capture these physical processes and are unable to reproduce water mass properties of the region. Dynamics at the continental slope are key for correctly modelling climate, yet their small spatial scale presents challenges both for ocean modelling and for observational studies. Crossslope exchange processes are also vital for the flux of nutrients such as iron from the continental shelf into the mixed layer of the Southern Ocean. An ironcycling model embedded in an eddypermitting ocean model reveals the importance of sedimentary iron in fertilizing parts of the Southern Ocean. Ocean gliders play a key role in improving our ability to observe and understand these smallscale processes at the continental shelf break. The Gliders: Excellent New Tools for Observing the Ocean (GENTOO) project deployed three Seagliders for up to two months in early 2012 to sample the water to the east of the Antarctic Peninsula in unprecedented temporal and spatial detail. The glider data resolve smallscale exchange processes across the shelfbreak front (the Antarctic Slope Front) and the front's biogeochemical signature. GENTOO demonstrated the capability of ocean gliders to play a key role in a future multidisciplinary Southern Ocean observing system.

Ocean processes at the Antarctic continental slope
Heywood, Karen J.; Schmidtko, Sunke; Heuzé, Céline; Kaiser, Jan; Jickells, Timothy D.; Queste, Bastien Y.; Stevens, David P.; Wadley, Martin; Thompson, Andrew F.; Fielding, Sophie; Guihen, Damien; Creed, Elizabeth; Ridley, Jeff K.; Smith, Walker
20140101
The Antarctic continental shelves and slopes occupy relatively small areas, but, nevertheless, are important for global climate, biogeochemical cycling and ecosystem functioning. Processes of water mass transformation through sea ice formation/melting and ocean–atmosphere interaction are key to the formation of deep and bottom waters as well as determining the heat flux beneath ice shelves. Climate models, however, struggle to capture these physical processes and are unable to reproduce water mass properties of the region. Dynamics at the continental slope are key for correctly modelling climate, yet their small spatial scale presents challenges both for ocean modelling and for observational studies. Crossslope exchange processes are also vital for the flux of nutrients such as iron from the continental shelf into the mixed layer of the Southern Ocean. An ironcycling model embedded in an eddypermitting ocean model reveals the importance of sedimentary iron in fertilizing parts of the Southern Ocean. Ocean gliders play a key role in improving our ability to observe and understand these smallscale processes at the continental shelf break. The Gliders: Excellent New Tools for Observing the Ocean (GENTOO) project deployed three Seagliders for up to two months in early 2012 to sample the water to the east of the Antarctic Peninsula in unprecedented temporal and spatial detail. The glider data resolve smallscale exchange processes across the shelfbreak front (the Antarctic Slope Front) and the front's biogeochemical signature. GENTOO demonstrated the capability of ocean gliders to play a key role in a future multidisciplinary Southern Ocean observing system. PMID:24891389

30 CFR 77.1911  Ventilation of slopes and shafts.
Code of Federal Regulations, 2010 CFR
20100701
... or air contamination from any other source; (4) Equipped with an automatic signal device designed to... be examined before each shift and the quantity of air in the slope or shaft measured daily by a... connected to the slope or shaft opening with fireproof air ducts; (3) Designed to permit the reversal of the...

Sedimentary processes on the Atlantic Continental Slope of the United States
Knebel, H.J.
19840101
Until recently, the sedimentary processes on the United States Atlantic Continental Slope were inferred mainly from descriptive studies based on the bathymetry and on widely spaced grab samples, bottom photographs, and seismicreflection profiles. Over the past 6 years, however, much additional information has been collected on the bottom morphology, characteristics of shallowsubbottom strata, velocity of bottom currents, and transport of suspended and bottom sediments. A review of these new data provides a much clearer understanding of the kinds and relative importance of gravitational and hydrodynamic processes that affect the surface sediments. On the rugged slope between Georges Bank and Cape Lookout, N.C., these processes include: (1) small scale mass wasting within submarine canyons and peripheral gullies; (2) density flows within some submarine valleys; (3) sand spillover near the shelf break; (4) sediment creep on the upper slope; and (5) hemipelagic sedimentation on the middle and lower slope. The area between Georges Bank and Hudson Canyon is further distinguished by the relative abundance of largescale slump scars and deposits on the open slope, the presence of icerafted debris, and the transport of sand within the heads of some submarine canyons. Between Cape Lookout and southern Florida, the slope divides into two physiographic units, and the topography is smooth and featureless. On the FloridaHatteras Slope, offshelf sand spillover and sediment winnowing, related to Gulf Stream flow and possibly to stormdriven currents, are the major processes, whereas hemipelagic sedimentation is dominant over the offshore slope along the seaward edge of the Blake Plateau north of the Blake Spur. Slumping generally is absent south of Cape Lookout, although one large slump scarp (related to uplift over salt diapirs) has been identified east of Cape Romain. Future studies concerning sedimentary processes on the Atlantic slope need to resolve: (1) the ages and

Submarine slope failures along the convergent continental margin of the Middle America Trench
NASA Astrophysics Data System (ADS)
Harders, Rieka; Ranero, CéSar R.; Weinrebe, Wilhelm; Behrmann, Jan H.
20110601
We present the first comprehensive study of mass wasting processes in the continental slope of a convergent margin of a subduction zone where tectonic processes are dominated by subduction erosion. We have used multibeam bathymetry along ˜1300 km of the Middle America Trench of the Central America Subduction Zone and deeptowed sidescan sonar data. We found abundant evidence of largescale slope failures that were mostly previously unmapped. The features are classified into a variety of slope failure types, creating an inventory of 147 slope failure structures. Their type distribution and abundance define a segmentation of the continental slope in six sectors. The segmentation in slope stability processes does not appear to be related to slope preconditioning due to changes in physical properties of sediment, presence/absence of gas hydrates, or apparent changes in the hydrogeological system. The segmentation appears to be better explained by changes in slope preconditioning due to variations in tectonic processes. The region is an optimal setting to study how tectonic processes related to variations in intensity of subduction erosion and changes in relief of the underthrusting plate affect mass wasting processes of the continental slope. The largest slope failures occur offshore Costa Rica. There, subducting ridges and seamounts produce failures with up to hundreds of meters high headwalls, with detachment planes that penetrate deep into the continental margin, in some cases reaching the plate boundary. Offshore northern Costa Rica a smooth oceanic seafloor underthrusts the least disturbed continental slope. Offshore Nicaragua, the ocean plate is ornamented with smaller seamounts and horst and graben topography of variable intensity. Here mass wasting structures are numerous and comparatively smaller, but when combined, they affect a large part of the margin segment. Farther north, offshore El Salvador and Guatemala the downgoing plate has no large seamounts but

NASA Astrophysics Data System (ADS)
Mercier, Denis; Coquin, Julien; Feuillet, Thierry; Decaulne, Armelle; Cossart, Etienne; Jónsson, Helgi Pall; Sæmundsson, Þorstein
20171101
In Iceland there are numerous rockslope failures, especially in the Tertiary basaltic formations of the northern, eastern and northwestern regions. The temporal pattern of rockslope failures is fundamental for understanding postglacial events. In the Skagafjörður district, central northern Iceland, 17 rockslope failures were investigated to determine the age of their occurrence. A geomorphic survey was carried out to identify and characterize landform units, both on the rockslope failures and in their immediate vicinity. In this coastal area, we used geomorphological stacking which included the relationship between rockslope failures and raised beaches caused by glacial isostatic rebounds, the chronology of which was established in previous studies. We searched for depressions on the rockslope failures to then excavate a series of pits and map the stratigraphy. The resulting stratigraphic framework was then validated using (i) radiocarbon dating of wood remains, and (ii) tephrochronology, both of which were complemented by agedepth model calibration. The results confirm that all the rockslope failures potentially occurred before the Boreal (8 ka), while 94% occurred before the Preboreal (10 ka). They all potentially occurred after the glacial retreat following the maximal ice extent and the Preboreal. More precisely, 11 of them potentially occurred between the Preboreal and the first half of the Holocene. This study demonstrates the relationship between the deglaciation and destabilization of slopes during the paraglacial phase (debuttressing, decompression, glacial isostatic rebound, seismic activity, etc.), which are also controlling factors favouring landsliding, but are difficult to identify for each individual rockslope failure.

Effect of Angle of Attack on Slope Climbing Performance
NASA Technical Reports Server (NTRS)
Creager, Colin M.; Jones, Lucas; Smith, Lauren M.
20170101
Ascending steep slopes is often a very difficult challenge for offroad vehicles, whether on Earth or on extraterrestrial bodies. This challenge is even greater if the surface consists of loose granular soil that does not provide much shear strength. This study investigated how the path at which a vehicle traverses a slope, specifically the angle that it is commanded to drive relative to the base of the hill (the angle of attack), can affect its performance. A vehicle was driven in loose sand at slope angles up to 15 degrees and angles of attack ranging from 10 to 90 degrees. A novel photogrammetry technique was implemented to both track vehicle motion and create a threedimensional profile of the terrain. This allowed for true wheel sinkage measurements. The study showed that though low angles of attack result in lower wheel slip and sinkage, the efficiency of the vehicles uphill motion increased at higher angles of attack. For slopes up to 15 degrees, a 90 degree angle of attack provided the greatest likelihood of successful ascent.

Physical Analysis Work for Slope Stability at Shah Alam, Selangor
NASA Astrophysics Data System (ADS)
Ishak, M. F.; Zaini, M. S. I.
20180401
Slope stability analysis is performed to assess the equilibrium conditions and the safe design of a humanmade or natural slope to find the endangered areas. Investigation of potential failure and determination of the slope sensitivity with regard to safety, reliability and economics were parts of this study. Ground anchor is designed to support a structure in this study. Ground anchor were implemented at the Mechanically Stabilized Earth (MSE) wall along Anak Persiaran Jubli Perak to overcome the further cracking of pavement parking, concrete deck and building of the Apartments. A result from the laboratory testing of soil sample such as index test and shear strength test were applied to the Slope/W software with regard to the ground anchors that were implemented. The ground anchors were implemented to increase the value of the factor of safety (FOS) of the MSE Wall. The value of the factor of safety (FOS) before implementing the ground anchor was 0.800 and after the ground anchor was implemented the value increase to 1.555. The increase percentage of factor of safety by implementing on stability of slope was 94.38%.

After the slippery slope: Dutch experiences on regulating active euthanasia.
Boer, Theo A
20030101
"When a country legalizes active euthanasia, it puts itself on a slippery slope from where it may well go further downward." If true, this is a forceful argument in the battle of those who try to prevent euthanasia from becoming legal. The force of any slippery slope argument, however, is by definition limited by its reference to future developments which cannot empirically be sustained. Experience in the Netherlandswhere a law regulating active euthanasia was accepted in April 2001may shed light on the strengths as well as the weaknesses of the slippery slope argument in the context of the euthanasia debate. This paper consists of three parts. First, it clarifies the Dutch legislation on euthanasia and explains the cultural context in which it originated. Second, it looks at the argument of the slippery slope. A logical and an empirical version are distinguished, and the latter, though philosophically less interesting, proves to be most relevant in the discussion on euthanasia. Thirdly, it addresses the question whether Dutch experiences in the process of legalizing euthanasia justify the fear of the slippery slope. The conclusion is that Dutch experiences justify some caution.

Verdin, Kristine L.; Godt, Jonathan W.; Funk, Christopher C.; Pedreros, Diego; Worstell, Bruce; Verdin, James
20070101
Landslides resulting from earthquakes can cause widespread loss of life and damage to critical infrastructure. The U.S. Geological Survey (USGS) has developed an alarm system, PAGER (Prompt Assessment of Global Earthquakes for Response), that aims to provide timely information to emergency relief organizations on the impact of earthquakes. Landslides are responsible for many of the damaging effects following large earthquakes in mountainous regions, and thus data defining the topographic relief and slope are critical to the PAGER system. A new global topographic dataset was developed to aid in rapidly estimating landslide potential following large earthquakes. We used the remotelysensed elevation data collected as part of the Shuttle Radar Topography Mission (SRTM) to generate a slope dataset with nearly global coverage. Slopes from the SRTM data, computed at 3arcsecond resolution, were summarized at 30arcsecond resolution, along with statistics developed to describe the distribution of slope within each 30arcsecond pixel. Because there are many small areas lacking SRTM data and the northern limit of the SRTM mission was lat 60?N., statistical methods referencing other elevation data were used to fill the voids within the dataset and to extrapolate the data north of 60?. The dataset will be used in the PAGER system to rapidly assess the susceptibility of areas to landsliding following large earthquakes.

Chen, Yulong; Irfan, Muhammad; Uchimura, Taro; Zhang, Ke
20180101
Rainfallinduced landslides are one of the most widespread slope instability phenomena posing a serious risk to public safety worldwide so that their temporal prediction is of great interest to establish effective warning systems. The objective of this study is to determine the effectiveness of elastic wave velocities in the surface layer of the slope in monitoring, prediction and early warning of landslide. The smallscale fixed and varied, and largescale slope model tests were conducted. Analysis of the results has established that the elastic wave velocity continuously decreases in response of moisture content and deformation and there was a distinct surge in the decrease rate of wave velocity when failure was initiated. Based on the preliminary results of this analysis, the method using the change in elastic wave velocity proves superior for landslide early warning and suggests that a warning be issued at switch of wave velocity decrease rate. PMID:29584699

Exploring Slope with Stairs & Steps
ERIC Educational Resources Information Center
Smith, Toni M.; Seshaiyer, Padmanabhan; Peixoto, Nathalia; Suh, Jennifer M.; Bagshaw, Graham; Collins, Laurena K.
20130101
As much as ever before, mathematics teachers are searching for ways to connect mathematics to reallife scenarios within STEM contexts. As students develop skill in proportional reasoning, they examine graphical representations of linear functions, learn to associate "slope" with "steepness" and rate of change, and develop…

Meterscale slopes of candidate MER landing sites from point photoclinometry
Beyer, R.A.; McEwen, A.S.; Kirk, R.L.
20030101
Photoclinometry was used to analyze the smallscale roughness of areas that fall within the proposed Mars Exploration Rover (MER) 2003 landing ellipses. The landing ellipses presented in this study were those in Athabasca Valles, Elysium Planitia, Eos Chasma, Gusev Crater, Isidis Planitia, Melas Chasma, and Meridiani Planum. We were able to constrain surface slopes on length scales comparable to the image resolution (1.5 to 12 m/pixel). The MER 2003 mission has various engineering constraints that each candidate landing ellipse must satisfy. These constraints indicate that the statistical slope values at 5 m baselines are an important criterion. We used our technique to constrain maximum surface slopes across large swaths of each image, and built up slope statistics for the images in each landing ellipse. We are confident that all MER 2003 landing site ellipses in this study, with the exception of the Melas Chasma ellipse, are within the smallscale roughness constraints. Our results have provided input into the landing hazard assessment process. In addition to evaluating the safety of the landing sites, our mapping of smallscale roughnesses can also be used to better define and map morphologic units. The morphology of a surface is characterized by the slope distribution and magnitude of slopes. In looking at how slopes are distributed, we can better define landforms and determine the boundaries of morphologic units. Copyright 2003 by the American Geophysical Union.

NASA Astrophysics Data System (ADS)
Oh, Seboong; Achmad Zaky, Fauzi; Mog Park, Young
20160401
The hydraulic behaviors in the soil layer are crucial to the transient infiltration analysis into natural slopes, in which unsaturated hydraulic conductivity (HC) can be evaluated theoretically from soil water retention curves (SWRC) by Mualem's equation. In the nonlinear infiltration analysis, the solution by some of smooth SWRCs is not converge for heavy rainfall condition, since the gradient of HCs is extremely steep near saturation. The van Genuchten's SWRC model has been modified near saturation and subsequently an analytical HC function was proposed to improve the van GenuchtenMualem HC. Using the examples on 1D infiltration analysis by the modified HC model, it is validated that any solutions can be converged for various rainfall conditions to keep numerical stability. Stability analysis based on unsaturated effective stress could simulate the infinite slope failure by the proposed HC model. The pore water pressure and the ratio of saturation increased from the surface to shallow depth (˜1m) and the factor of safety decreased gradually due to infiltration. Acknowledgements This research is supported by grants from Korean NRF (2012M3A2A1050974 and 2015R1A2A2A01), which are greatly appreciated.

Correlation of heart rate/ST slope and coronary angiographic findings.
Balcon, R; Brooks, N; Layton, C
19840101
The heart rate/ST slope was evaluated in 49 patients undergoing routine investigation for possible coronary artery disease. The slope correctly predicted the absence of any 75% stenoses in the seven patients to whom this applied; it was, however, correct for only four of 30 with one stenosis, one of 10 with two, and neither of the patients with three. Distinct slope ranges were not found, and the previously published ranges said to be specific for no significant stenosis and one, two, and three vessel disease were not. PMID:6466516
 «
 21
 22
 23
 24
 25
 »
Some links on this page may take you to nonfederal websites. Their policies may differ from this site.