Slope Location Research Articles

A river flash flood forecasting model coupled with ensemble Kalman filter

AbstractA flash flood forecasting model including a state‐of‐the‐art data assimilation method was developed to provide a precise water stage forecast for flood emergency response. The model integrates a flash flood routing model (FFRM) coupled with an ensemble Kalman filter (EnKF) and an artificial neural network (ANN) submodel. In the model, the ANN forecasts river water stages at gauge stations first. Then, these are used as the initial and boundary conditions of the FFRM. The water stages, simulated from the FFRM, are then corrected by the EnKF for lead time. The model was applied to the Tanshui River watershed in northern Taiwan during past typhoons. The model forecasts almost covered the data observed during a typhoon period to within 95% confidence intervals. Compared with the use of FFRM without EnKF, the forecast water stages from the EnKF improved the accuracy at the conjunctions between upstream and downstream channels and the steep slope location.

Early Pleistocene lake formation and hominin origins in the Turkana–Omo rift

Prior research has correlated the formation of Plio-Pleistocene lakes in East Africa to global/regional climate changes and interpreted the lacustrine basins as significant settings of hominin evolution. Paleo-Lake Lorenyang from the Turkana–Omo rift is important to these issues, as its marginal deposits contain some of, if not the earliest currently known specimens of Acheulian stone tools and African Homo erectus. Magnetostratigraphic and sedimentological evidence indicates that the oldest preserved paleo-Lake Lorenyang deposits are dated at 2.148–2.128 Ma and derive from the NW Turkana basin, predating those from the Omo basin by ∼100 kyr and the NE Turkana basin by ∼190 kyr. Apparently, the lake expanded asynchronously in the rift, potentially due to a volcano-tectonic influence on the location of drainage networks, depositional slopes, or topographic elevation differences within and between the basins at the time of flooding. The onset of the lake temporally coincides with the eruption of basalt lava flows dated to 2.2–2.0 Ma that blocked the southeast outlet of the Turkana basin. This provides a plausible mechanism for hydrologic closure and lacustrine basin formation through volcano-tectonic impounding. It also points to a non-climatic cause for the initial formation of paleo-Lake Lorenyang at ∼2.14 Ma. First appearances for African H. erectus (∼1.87 Ma) and Acheulian tools (∼1.76 Ma) in the Turkana–Omo rift postdate the lake's initial formation by about 270 kyr and 380 kyr, respectively. Such timing differences contrast with studies that correlate all three to the 400-kyr-eccentricity maximum at 1.8 Ma. Although the Turkana–Omo rift is just one example, it does provide alternative insights to views that link climate, hominin evolution, and lake formation in East Africa.

A probabilistic approach for landslide hazard analysis

We present a general framework for probabilistic landslide hazard analysis. With respect to other quantitative hazard assessment approaches, this probabilistic landslide hazard analysis has the advantage to provide hazard curves and maps, and to be applicable to all typologies of landslides, if necessary accounting for both their onset and transit probability.The method quantifies, for a given slope location, the exceedance probability of being affected by a landslide with a specific local intensity within a reference time interval, i.e. the hazard curve, under the common assumption that landslides behave as a Poisson process. Hazard maps are calculated, reducing the hazard curve to single values by choosing a fixed probability of exceedance following standards or regulation requirements. The method is based on the assessment of a landslide onset frequency, a runout frequency for long-runout landslides, and the local definition of landslide intensity, which can be expressed through different parameters, according to landslide typology. For long runout landslides, the runout and spatially-varying intensity and uncertainty are considered.Hazard curves and maps play a fundamental role in the design and dimensioning of mitigation structures, in land planning and in the definition of risk and hazard management policies. Starting from the general framework, we apply the methodology for rockfall hazard analysis, and we test it in an area affected by the Christchurch 2011 earthquake, New Zealand, which triggered a large number of rockfalls, killing five people.

基于RS与GIS的农村居民点空间变化特征与景观格局影响研究

PDF HTML阅读 XML下载 导出引用 引用提醒 基于RS与GIS的农村居民点空间变化特征与景观格局影响研究 DOI: 10.5846/stxb201307291976 作者: 作者单位: 四川师范大学 西南土地资源评价与监测教育部重点实验室,四川师范大学 西南土地资源评价与监测教育部重点实验室,四川师范大学,四川师范大学 西南土地资源评价与监测教育部重点实验室 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（41301196）；国家社会科学基金项目（11XJY019）；国家973项目（2009CB421105） A study of spatial evolution characteristics of rural settlements and influences of landscape patterns on their distribution using GIS and RS Author: Affiliation: Key Lab of Land Resources Evaluation and Monitoring in Southwest,Ministry of Education,Sichuan Normal University,Key Lab of Land Resources Evaluation and Monitoring in Southwest,Ministry of Education,Sichuan Normal University,,Key Lab of Land Resources Evaluation and Monitoring in Southwest,Ministry of Education,Sichuan Normal University Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:农村居民点作为乡村地域空间人口聚居形态，是乡村聚落景观重要组成部分，其空间布局、演变特征受自然、社会、经济多重因素的影响。利用都江堰市2005年和2010年两期遥感影像提取农村居民点、坡度、道路、河流等矢量数据，借助RS、GIS空间分析技术，定量研究都江堰市农村居民点的空间变化过程、格局和趋势，并选取景观格局指数对影响农村居民点布局特征的因素进行深入分析。结果表明：（1）2005年和2010年都江堰市农村居民点的空间分布总体上均表现出显著的聚集趋势，2010年农村居民点的聚集程度要比2005年高，但居民点集聚的空间态势没有发生明显变化，仍然集中在都江堰市的东南部；（2）坡度、道路和河流对都江堰市农村居民点的布局有显著影响，其中超过80%的居民点分布在0-10°坡度范围内，超过50%的居民点分布在道路500 m范围内，近60%居民点分布在河流1000 m范围内；（3）农村居民点空间布局除了受地形因素影响外，还与国家级风景名胜区、世界文化遗产区等保护政策，农村土地综合整治和灾后重建等规划因素密切相关。该研究以期为农村居民点动态变化监测、农村土地整理效果评价、新农村规划等理论和实践提供重要决策参考和技术支撑。 Abstract:Forms of human habitation within rural settlements are a major component of rural landscapes. The spatial patterns and evolutionary characteristics of rural settlements are influenced by multiple factors, including natural, social, and economic elements. It is, therefore, important not only to properly identify and assess the spatial distribution patterns and evolutionary modes of rural settlements, but also to uncover causative laws and influential factors behind their evolution. This can facilitate scientific rural planning and enhance optimal distribution of urban and rural land resources. Our study is based on a series of digitalized vector data, including the locations of rural settlements, land slopes, rivers, and road networks obtained from remote sensing (RS) images of the city of Dujiangyan in Sichuan Province for 2005 and 2010. We applied analytical techniques derived from Geographic Information Systems (GIS) and RS to quantitatively analyze the processes, patterns, and trends of spatial evolution in rural settlements. Specifically, we explored landscape pattern indexes to examine in depth the factors influencing the distribution characteristics of rural settlements in the study area. Our results showed that: 1) In general, while there was significant clustering in the spatial distribution of rural settlements in Dujiangyan during both 2005 and 2010, this settlement pattern was even more significant in 2010. Along with an increase in the spatial scale, the degree of the clustering tendency also increased, reaching a maximum value at a scale of 13 km. 2) The presence of land slopes, roads, and rivers significantly influenced the distribution of rural settlements in Dujiangyan as evidenced by the following findings. More than 80% of settlements were located in areas with slopes of less than 10 degrees; over 50% of settlements were located within 500 m from a road network; and almost 60% were distributed within 1000 m of a river. 3) In 2005 as well as 2010, there was no obvious change in the concentrated locations of clusters, which were consistently found in the southeastern region of Dujiangyan City. However, during both time periods, fewer settlements were found in the townships of Hongkou, Longchi, and Qingcheng Mountain. The reason for this imbalance in the spatial distribution of rural settlements was that besides the influence by natural factors such as the landscape, the distribution patterns of rural settlements in Dujiangyan were also closely associated with several planning elements. These included a policy of protecting national regions of scenic interest and a World Cultural Heritage site located in the city, the rural land comprehensive consolidation projects and post-earthquake reconstruction planning. 4) Based on the above findings on factors that influence the distribution of rural settlements, our research suggests that comprehensive consideration of topographical and geological conditions is required for optimal adjustment of rural settlement patterns. Scientific planning procedures can promote the relocation of rural residents from villages to townships and urban areas, and help to lessen disruption in environmentally protected regions. They can also reinforce the effective use of land resources and increase land supporting capabilities. We expect our research to provide a methodological reference for similar research conducted in the future. It can also provide a theoretical and practical reference for rural land-related decision-making and technical support, for example, dynamic monitoring of changes in rural settlements, assessments of rural land consolidation, and the "New Socialist Countryside" rural planning policy. 参考文献 相似文献 引证文献

Numerical Simulation on the Regular Pattern of the Lateral Friction Transmission of the Pile in the Incline under the Pulling Force

The regular pattern of the lateral friction transmission is one of the most critical influences on the ultimate uplift bearing capacity. The pile foundation in the incline under the pulling force has a wide variety of characteristics which is different with the normal pile. Numerical simulation is done by the use of FLAC3D in this paper. The regular pattern of the lateral friction transmission of the pile in the incline under the pulling force is studied. And the influence factors on the lateral friction transmission such as the slope gradient, the length and location of piles are discussed. The results show that the incline has a great influence on the lateral friction transmission. The lateral friction which is away from the incline-side is about 30% to 50% bigger than the incline-side. The slope gradient and the location of piles all have a great influence on the lateral friction transmission.

Coal Mining Influences on the Soil Water Content in Mao Wusu Sand Land

The soil water content in a region is closely related to plant growth. The coal Mining has a strong influence on the soil in Mao Wusu sand land. This study investigated the relationship between the soil water content and the collapse Degree Land of Coal Mining. Samples of the collapse land were analyzed for the soil water content in different slope locations in summer. The soil moisture changes are basically same in different slope location regardless whether it is in subsidence area or not when no rain occurs within two weeks in summer, and soil water content is relatively low in slope button, and a relative high in the other slope location, the water content in the control area and subsidence area follows from high to low by: 0a> 3a> 2a> 1a. The soil water content of the control region each layer is significantly higher than that of the subsidence region.The soil volumetric water content of the sample land on both sides of the subsidence cracks is less than that in the control land in the experimental period. The water content of relative subsidence side is higher than in the exposed side, and the water content is shown the law of the control area>light >light-exposed>medium>medium-exposed>heavy>heavy-exposed.

Factors controlling the types of microbial consortia in cold-seep environments: A molecular and isotopic investigation of authigenic carbonates from the South China Sea

Authigenic carbonates were recovered from several locations of the South China Sea continental slope at a 470m to 770m water depth. The sources of seeping fluids, the time involved in carbonate formation and the potential driving forces are increasingly understood, but little is known about the biogeochemical processes that occur during this type of carbonate precipitation. Here, a molecular and isotopic investigation of authigenic carbonates was conducted to determine the factors controlling the types of microbial consortia in cold-seep environments. The studied carbonates were one aragonitic crust and three high-Mg calcitic tubular concretions from specific sites. A significant input of biogenic methane to the carbon pool during the precipitation of the carbonates was suggested by the presence of 13C-depleted molecular fossils of methanotrophic archaea (with δ13C values as negative at −141.5‰) and sulfate-reducing bacteria (with δ13C values as negative at −128.5‰). The methane was primarily oxidized in an anaerobic process. The predominant consortia were ANME-2 assemblages in the aragonitic carbonate (sample TVG3-C2), whereas high-Mg calcitic carbonates (samples TVG14-C2 and TVG8-C5) were dominated by ANME-1 assemblages according to the specific biomarkers observed. Taking the favored environments for specific AOM consortia and crystallization conditions for aragonite and calcite together, the factors selecting for specific AOM communities appear to be constrained by their biogeochemical settings. Accordingly, higher alkalinity, abundant sulfate concentration and being closer to the water–sediment interface conditions favor the precipitation of aragonite over high-Mg calcite.

3-D image analysis on palate growth changes from birth to 1 month in healthy infants

In order to study the relations of malocclusion formation and feeding behavior as a scientific research project, we measured the 3-D morphology of 31 healthy newborns within 7 days of birth and 1 month later using dental casts. Nine characteristics were selected and the developmental changes were analyzed using specialized software for investigating palatal development in detail. The results revealed that the palatal width, 3 palatal characteristics relating to depth, maximum slope location, and mean slope increased significantly during the 1 month, but there were no significant changes observed in palate length, cuspid ratio, and maximum slope. There was a significant correlation between palate depth and maximum depth point location, suggesting that the deeper points tended to be located further back. No significant correlations were observed between newborns within 7 days of birth and 1 month after birth for cuspid ratio, maximum depth point location, and maximum slope. Our observation of inter-characteristics correlations revealed 7 significant (P < 0.01) combinations out of a total of 33 combinations were observed in newborns within 7 days of birth, while only 4 were observed in 1-month-old infants. This appears to have been because of morphological changes occurring between individuals due to growth. Thus, it was clarified that not only size but shape (cuspid ratio, maximum slope point location, and the mean slope) also changes over the first month after birth.

天山盘羊夏季采食地和卧息地生境选择

PDF HTML阅读 XML下载 导出引用 引用提醒 天山盘羊夏季采食地和卧息地生境选择 DOI: 10.5846/stxb201306081468 作者: 作者单位: 新疆农业大学动物科学学院,秦岭国家植物园,新疆维吾尔自治区林业厅野生动植物保护处,新疆农业大学 作者简介: 通讯作者: 中图分类号: Q958.1 基金项目: 国家国际科技合作计划 （2010DFA92720） Foraging and bed site selection of Tianshan argali(Ovis ammon karelini)in Central Tianshan Mountains in Summer Author: Affiliation: College of Animal Science,Xinjiang Agricultural University,,,College of Animal Science,Xinjiang Agricultural University Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:2010年7-8月采用样线调查法及直接观察法对天山中部古仁郭楞高山区的盘羊天山亚种采食地和卧息地生境进行了研究。共调查5条沟系的12条样线，测量天山盘羊147个采食地和136个卧息地样方，分析了13类生态因子对天山盘羊采食地和卧息地选择的影响。研究结果表明，天山盘羊夏季采食地与卧息地在坡位、坡向、地貌类型、海拔高度、距最近家畜距离、距道路距离和距居民点距离差异极显著（P < 0.01），植被高度差异显著（P < 0.05），而其它生态因子差异性不显著（P > 0.05）；相对卧息地的选择而言，夏季盘羊采食地的选择更偏爱海拔较低，植被高度低，距离道路、居民点和最近家畜距离近的半阴半阳坡，山体中下位的高山草甸缓坡生境。逐步判别分析表明，距道路距离、距居民点距离、植被高度、距家畜距离4个生态因子可以用于判别夏季天山盘羊采食地与卧息地生境，正确区分率达到90.6%。 Abstract:Foraging and bed sites are the two key habitats for the ungulate, but researches on the differences between these two habitats are little. During the summer we studied the foraging and bed sites selection for Tianshan argali(Ovis ammon karelini)in Gurenguoleng areas of Central Tianshan Mountains, Xinjiang Uygur Autonomous Region, China. According to the population and distribution of Tianshan argali in this region, we collected the ecological factors via line transect and quadrat sampling methods. During July and August in 2010, we investigated the Tianshan argali among 12 lines transects in total along 5 ditches. Line transects were allocated from the bottom to the ridge of the mountain covering all typical vegetation in this region. Due to the huge mountain and wide basin in the studied area, direct observation method can be used to determine Tianshan argali's habitat. We stood far away from the argali pack to observe their foraging or bed sites via the telescope until the targeted argali left. Then one of colleagues was responsible for guiding the other person to find the targeted area by the telescope. Some of the bed sites were confirmed by trace detection by the surrounding factors such as the fresh bed trace and fecal pellet, footprint, urine, hair, etc. The foraging and bed track of Tianshan argali was marked as the center for a 10 m×10 m quadrat when it was found during the field investigation, and the quadrat center was located with Garmin-72 GPS. In this field investigation we observed 157 foraging and 136 bed sites for Tianshan argali with 13 ecological factors: elevation, slope, slope direction, slope location, landscape type, vegetation height, vegetation coverage, hiding level, distance from road, distance to water resource, distance to livestock, distance to human settlements and number of plant species on habitat selection by Tianshan argali were thoroughly evaluated in this research. The results showed that there were no significant differences between foraging and bed sites for Tianshan argali to live among the factors in slope, hiding cover level, distance to water resource, number of plant species and vegetation coverage in summer (P > 0.05), however, the factors in altitude, distance to livestock (P < 0.01); vegetation height (P < 0.05), slope location, slope direction and landscape types (P < 0.01) were the significant factors for the Tianshan argali to live. Compared with bed sites, Tianshan argali preferred to choose the foraging sites at lower elevation, lower vegetation height, closer to roads, human settlements and livestock, habitats of a mountain alpine meadow in the semi-shaded slope and grassland in gentle slope in summer. During the long field investigation and observation we could find that there were 4 essential ecological factors play an important role in distinguishing the foraging and bed sites. We ordered them according to their contribution value index: distance to road, distance from the settlements, vegetation height and distance to livestock. Based on the mentioned ecological factors variables, the accurate rate for distinguishing the foraging and bed sites of Tianshan argali reached 90.6%. The results fully demonstrated that there was obvious habitat separation between foraging and bed sites for Tianshan argali to live during summer. Therefore, the pattern of habitat selection by Tianshan argali seemed to be strongly influenced by food, predator and disturbance. 参考文献 相似文献 引证文献

Structural Damage Detection of Unsaturated Soil Embankment Slope Based on Artificial Neural Network under the Rainfall Infiltration

Based on BP neural network, simulation analysis of damage location and degree of unsaturated soil embankment slope under rainfall infiltration are made using finite element method. The simulation model is established by rainfall infiltration statistical characteristics as the main input vector. The results show that the artificial neural network can accurately identify the damage location and the damage degree of the slope.

Comparative Study on Landslide Hazard Deformation Forecast Method

The key problem which the control of landslide hazard is the prediction of landslide fatalness, successful landslide forecast can consumedly decrease the loss caused by landslide hazard. Landslide spatial forecast can determine the location of unstable slope. For a certain landslide in Three Gorges Reservoir area, according to the existing monitoring data and analysis methods, such as: nonlinear regression analysis method, exponential smoothing and gray prediction method, to forecast deformation tendency of landslide from quantitative point and take comparative study. Results indicate that the gray prediction method is more tally with the reality in the deformation prediction. It can provide reference for deformation forecast of similar landslide or slope prevention in chongqing and Three Gorges Reservoir area.

Spatiotemporal Variability of Soil Moisture under Different Agroforestry Landscape in Jinghe River

Measured the cover soil water content in soil layer 0~30cm of different agroforestry landscape types in Jinghe river with TDR, the landscape types including sloping cropland, apple orchard, apple-clover system, land under forest and grass changed from grain crop and black locust forest. Analyze the distribution characteristic and spatiotemporal variability of the cover soil water. The result showed that the soil water has renewed in a certain extent after a rain period in 1.5 m soil profile; the soil water content is gradually increased from the top of to the bottom of the slope under the affection of the slope location and plant category. The theory model of semivariogram for cover soil water content before rain season and after season, the value of nugget is changed no obviously , and they are 0.25 and 0.30; ranges is 99.7 m and 87.6 m. And the results indicated that soil moisture exhibited high fractal dimensions and clear spatial autocorrelation. The fractal dimensions are 1.71 and 1.74, variogram is main autocorrelation. During rain season the theory semivariogram model is linear, the spatiotemporal variability of soil water content becomes higher with the increase in distance, and its fractal dimension is 1.40.

Detection and Boundary Identification of Phonocardiogram Sounds Using an Expert Frequency-Energy Based Metric

This paper presents a new method to detect and to delineate phonocardiogram (PCG) sounds. Toward this objective, after preprocessing the PCG signal, two windows were moved on the preprocessed signal, and in each analysis window, two frequency-and amplitude-based features were calculated from the excerpted segment. Then, a synthetic decision making basis was devised by combining these two features for being used as an efficient detection-delineation decision statistic, (DS). Next, local extremums and locations of minimum slopes of the DS were determined by conducting forward-backward local investigations with the purpose of detecting sound incidences and their boundaries. In order to recognize the delineated PCG sounds, first, S1 and S2 were detected. Then, a new DS was regenerated from the signal whose S1 and S2 were eliminated to detect occasional S3 and S4 sounds. Finally, probable murmurs and souffles were spotted. The proposed algorithm was applied to 52min PCG signals gathered from patients with different valve diseases. The provided database was annotated by some cardiology experts equipped by echocardiography and appropriate computer interfaces. The acquisition landmarks were in 2R (aortic), 2L (pulmonic), 4R (apex) and 4L (tricuspid) positions. The acquisition sensor was an electronic stethoscope (3M Littmann® 3200, 4kHz sampling frequency). The operating characteristics of the proposed method have an average sensitivity Se=99.00% and positive predictive value PPV=98.60% for sound type recognition (i.e., S1, S2, S3 or S4).

Vulnerability of the northern Mongolian steppe to climate change: insights from flower production and phenology

The semiarid, northern Mongolian steppe, which still supports pastoral nomads who have used the steppe for millennia, has experienced an average 1.7 degrees C temperature rise over the past 40 years. Continuing climate change is likely to affect flowering phenology and flower numbers with potentially important consequences for plant community composition, ecosystem services, and herder livelihoods. Over the growing seasons of 2009 and 2010, we examined flowering responses to climate manipulation using open-top passive warming chambers (OTCs) at two locations on a south-facing slope: one on the moister, cooler lower slope and the other on the drier, warmer upper slope, where a watering treatment was added in a factorial design with warming. Canonical analysis of principal coordinates (CAP) revealed that OTCs reduced flower production and delayed peak flowering in graminoids as a whole but only affected forbs on the upper slope, where peak flowering was also delayed. OTCs affected flowering phenology in seven of eight species, which were examined individually, either by altering the time of peak flowering and/or the onset and/or cessation of flowering, as revealed by survival analysis. In 2010, which was the drier year, OTCs reduced flower production in two grasses but increased production in an annual forb found only on the upper slope. The particular effects of OTCs on phenology, and whether they caused an extension or contraction of the flowering season, differed among species, and often depended on year, or slope, or watering treatment; however, a relatively strong pattern emerged for 2010 when four species showed a contraction of the flowering season in OTCs. Watering increased flower production in two species in 2010, but slope location more often affected flowering phenology than did watering. Our results show the importance of taking landscape-scale variation into account in climate change studies and also contrasted with those of several studies set in cold, but wetter systems, where warming often causes greater or accelerated flower production. In cold, water-limited systems like the Mongolian steppe, warming may reduce flower numbers or the length of the flowering season by adding to water stress more than it relieves cold stress.

Spatial and Temporal Variance of Metal and Suspended Solids Relationships in Urban Stormwater—Implications for Monitoring

Relationships between total suspended solids (TSS) and metals (Cu, Pb and Zn) were tested and compared amongst base and high flows of three urbanised catchments in Sydney Estuary, Australia. Significant relationships between TSS and Cu, Pb and Zn were detected for high flows within each catchment; however, no significant relationship was detected for TSS/Zn and TSS/Cu in one of the creeks (Whites Creek) and for TSS/Zn in another (Hawthorne Canal) in 2010 during base flow. Relationships between metals and TSS also varied significantly in locations of intercept and slope between high and base flow and amongst catchments. Spatial variance in TSS/metal relationships were likely caused by specific anthropogenic activities because land uses, meteorology and geology within the study catchments were similar. Results suggest TSS may be used as a surrogate for estimating metal loading in real time for urban catchments, once relationships between metals and TSS were established for individual catchments and for base and high flow conditions. Moreover, no differences in TSS/metal relationships were detected between 2009 and 2010 in Hawthorne Canal during high flow conditions, suggesting that this method of real-time monitoring may be reliable for assessing Cu, Pb and Zn loads during high flows over inter-annual periods. However, long-term consistency of TSS/metal relationships for base flow may need testing since changes in TSS/Zn and TSS/Cu relationships were detected between 2009 and 2010 in Hawthorne Canal. Although irregular discharges to stormwater did not conform to TSS/metal relationships, irregular discharges may be detected in real time by increased flow during dry weather conditions, which may facilitate regulation of these conditions that currently result in potential environmental harm to aquatic biota in Sydney Estuary.

Unloading Triaxial Experimental Study on Stress Path of Excavated Soil Slope

The current research was implemented to study the practical unloading stress path that the slope mass experienced during the excavation process, which is very important in the stress and strain numerical analysis. Series of unloading tests were carried out under different confining pressure. During the test process, the minor principal stress was kept decreasing, while the major principal stress was kept unchanged to simulate the stress path in some locations of the soil slope, such as at the top of the slope. The corresponding conventional triaxial compression tests were also carried out as comparison. It is shown that there are many differences between the unloading and loading tests. Through analyzing, the tests results could be applied in the development of unloading constitutive models of excavation soil mass. Also, such unloading tests data are valuable in calibration and verification of the current existing popularly used models.

Correlation of Pelvic Orientation With Adult Scoliosis

Prospective analysis of elderly volunteers with adult scoliosis. To analyze the correlation between the sagittal pelvic parameters and adult scoliosis. There are little data on the relationship between the sagittal pelvic parameters and adult scoliosis. The study group comprised 108 elderly volunteers (21 men and 87 women). All underwent anteroposterior and lateral radiographs of whole spine including hip joints. The participants were classified into 3 groups: normal (Cobb angle <10 degrees), low grade (Cobb angle 10 to 19 degrees), and high grade (Cobb angle ≥20 degrees). The radiographic parameters were magnitude, location and direction of curves, sacral slope, pelvic tilting, pelvic incidence, S1 overhang, thoracic kyphosis, lumbar lordosis, and C7 plumbline. Statistical analysis was performed to identify the significant differences between the groups. Analysis of variance and Pearson correlation coefficient were used to determine the significance. The mean age and Cobb angle of the participants was 73 years (range: 61 to 87 y), and 11.2 degrees (range: 0.3 to 36.3 degrees), respectively. There were no significant differences in the sacral slope, thoracic kyphosis, and lumbar lordosis between the 3 groups (P>0.05, analysis of variance). The mean pelvic tilting of the high-grade or low-grade groups was significantly higher than that of the normal group (P<0.0001, P=0.003, Tukey HSD post hoc test). The high-grade group had significantly higher pelvic incidence than either the low-grade or normal groups (P=0.016, P<0.0001), and the low-grade group had higher pelvic incidence than the normal group (P<0.0001). The high-grade or low-grade groups had a significantly higher S1 overhang than the normal groups (P<0.0001, P=0.002). Comparing the C7 plumbline, high-grade or low-grade groups had a significantly higher value than normal groups (P<0.0001, P=0.012). The pelvic incidence, pelvic tilting, and S1 overhang were significantly correlated with the magnitude of curvature (r=0.592, P=0.0001; r=0.434, P=0.0001; and r=0.461, P=0.0001, respectively). There was a significant correlation between the sagittal pelvic parameters and adult scoliosis in elderly volunteers. There was a significant difference in the pelvic incidence between the normal, low-grade, high-grade adult scoliosis groups. The pelvic tilting and S1 overhang of the high-grade or low-grade groups were significantly higher than the normal group. These 3 parameters were also associated with the magnitude of curvature.

Winter foraging habitat selection of brown-eared pheasant ( Crossoptilon mantchuricum) and the common pheasant ( Phasianus colchicus) in Huanglong Mountains, Shaanxi Province

The foraging habitat selections of brown-eared pheasant ( Crossoptilon mantchuricum) and the common pheasant ( Phasianus colchicus) were studied in Huanglongshan Nature Reserve Shaanxi, China. Foraging habitat characteristics were measured on the basis of expected differences between species at 183 sites from November to December 2006 and January 2007. The results showed that both species selected foraging habitats with altitude (<1200 m), conifer forest, half sunny and half shady slope, sunny slope, density of trees (<5 individuals/100 m 2), cover of shrub (>50%), visibility class (<10%) and distance to water source (<300 m). However, the brown-eared pheasant selected habitats with cover of trees (30–50%), middle or lower slope location, distance to edge of woods (<300 m) and human disturbance (<500 m), and the selection on density of shrub was not observed, compared to the selections on cover of trees (<30%), lower slope location, distance to edge of woods (<500 m) and human disturbance (<300 m), and density of shrub (>500 individuals/100 m 2) for common pheasant. We also found that the common pheasant avoid predators by concealment whereas brown-eared pheasant evade predations by running away strategy.

Study on discrete form algorithm of cutter location surface in CNC milling of freeform surface

A novel discrete form algorithm of cutter location surface is proposed to produce 3D tool paths in computer numerical control (CNC) 3-axis milling of freeform surface. As compared with the normal form algorithm, it can be applied to the complex curve surface and irregular shape cutter. The research objective is to identify the discrete form algorithm of cutter location surface. First, the cutter working surface and the machined curve surface were dispersed to be two-point clouds, respectively. Next, the tangency mode of their point clouds was established to produce the cutter location surface. Then, CNC milling experiments were carried out to identify the machined form errors for discrete and normal form algorithms. Finally, the effects of discrete form parameters and workpiece surface posture were investigated on the discrete form accuracy. Experimental results show that the machined form errors for the discrete form algorithm is identical to that for normal form algorithm, but its large form errors are mainly distributed on the large workpiece slope location. On decreasing searching interval and lattice grid size, the discrete form accuracy increases. Moreover, the workpiece surface posture greatly influences the discrete form accuracy, but there exists such a workpiece surface posture that the best discrete form accuracy may be achieved. It is concluded that the discrete form algorithm is feasible to produce the cutter location surface for CNC milling of freeform surface by controlling lattice grid size and searching interval and choosing a suitable workpiece surface posture.

Evaluating debris slide occurrence using digital data: paraglacial activity in Chilliwack Valley, British Columbia

Debris sliding is one of the most important processes acting to transport sediment within mountainous regions. Detailed study of debris slide activity at the basin scale typically involves landslide inventories generated from aerial photographs. However, it has been shown that some types of rapid mass movement can be accurately identified using a combination of high-resolution satellite imagery and digital elevation data. This approach is beneficial as the digital products allow for a more accurate and efficient data throughput into various types of geomorphic analysis. Here, we demonstrate the use of an automated inventory in the geomorphometric evaluation of debris slide initiation for the Chilliwack Basin, British Columbia, Canada. Our results indicate that the occurrence of debris sliding is primarily determined by topographical controls. For basins that are in equilibrium with the existing climate, the frequency of debris sliding should demonstrate a strong relationship to bedrock geology as the production of unconsolidated materials available for failure is a function of weathering rates under these conditions. The lack of bedrock control within the Chilliwack Basin suggests a state of paraglacial relaxation, wherein glacial deposits dominate the sediment cascade within the area. Therefore, topographic parameters can be used to discriminate the location of metastable slopes where debris slide erosion will be active. The use of digital data in the characterization of debris slide occurrence would seem to be a viable alternative to the more traditional methods.