退耕还林政策实施的农户水土保持行为响应研究--以江西省丰城市梅林镇为例     

翟文侠  黄贤金 《云南地理环境研究》2006,18(2):33-39

农户水土保持行为与生态环境变化关系密切，分析农户水土保持行为响应机理对退耕还林政策的实施具有重要意义。通过对江西省丰城市梅林镇多元回归模型分析，结果表明：（1）农户水土保持行为与退耕还林实施力度、退耕地收入与退耕还林后补偿比重成正相关，与退耕补偿年限成负相关；（2）农户水土保持投入减少反映农户家庭收入结构发生变化：从农业为主的收入阶段向以非农业或农业与非农业收入为主的阶段转变；（3）退耕还林政策实施农户水土保持行为响应以效益引导型为主。据此，提出相关建议。  相似文献   

硅酸盐体系的化学平衡:(1)物质平衡原理   总被引：6，自引：5，他引：6  

马鸿文  杨静  刘贺  李贺香  白志民  王庆华 《现代地质》2006,20(2):329-339

通过具体应用实例,系统介绍了在硅酸盐体系的化学平衡研究中,依据物质平衡原理,求解“相混合方程”(PME)而进行物相定量分析的“相混合计算”(PMC)方法。应用实例包括矿物原料和结晶岩物相的定量分析,复杂固溶体矿物的端员组分计算,多组分硅酸盐陶瓷的配料比例计算,以及硅酸盐陶瓷制品物相的定量分析。物相定量分析结果是结晶岩和工业岩石原料分类命名的基础,可以为改进矿物原料预处理工艺提供依据,也是研究硅酸盐体系的化学平衡、对材料制备过程进行热力学分析的基础。实际计算中必须合理估计各种分析数据的累积误差。优化计算结果的理论依据主要有矿物晶体化学原理、矿物共生组合规律和次要组分分配的固溶体矿物相优先原则。  相似文献   

Study on strength reduction factors considering the effect of classification of design earthquake   总被引：1，自引：0，他引：1  

翟长海  谢礼立 《地震学报(英文版)》2006,19(3):299-310

Introduction The strength reduction factor is defined as the lateral yielding strength required to avoid yielding in the system when subjected to a given ground motion, to the lateral yielding strength required to maintain the displacement ductility ratio demand equal to a pre-determined target duc-tility ratio under the same ground motion. The strength reduction factors are not only the key fac-tors in determining seismic action for force-based seismic design, but also one of the key parame-t…  相似文献   

支持向量机(SVM)及其在场预测中的应用   总被引：2，自引：3，他引：2  

张礼平  陈永义  周筱兰 《热带气象学报》2006,22(3):278-282

介绍一种新的非线性回归分析方法--SVM回归.利用EOF能分解数据场和SVM回归分析可建立因子与预报量非线性关系的优势,设计预报方案：（1） 将因子场和预报场分别用方差标准化、EOF场展开,提取两场时间系数;（2） 用SVM回归分析实现因子场时间系数对预报场时间系数非线性预测;（3） 由预测的预报场时间系数与对应空间函数反演原场.用交叉检验的方法,对1960～2003年1月热带海表温度场预报汛期（6～8月）华中区域降水场进行试验.SVM回归44年独立预报平均技巧评分10.4%,较随机预报具有明显的技巧水平,优于经典回归.  相似文献   

Application of logistic regression for landslide susceptibility zoning of Cekmece Area, Istanbul, Turkey   总被引：6，自引：0，他引：6  

T. Y. Duman  T. Can  C. Gokceoglu  H. A. Nefeslioglu  H. Sonmez 《Environmental Geology》2006,51(2):241-256

As a result of industrialization, throughout the world, cities have been growing rapidly for the last century. One typical example of these growing cities is Istanbul, the population of which is over 10 million. Due to rapid urbanization, new areas suitable for settlement and engineering structures are necessary. The Cekmece area located west of the Istanbul metropolitan area is studied, because the landslide activity is extensive in this area. The purpose of this study is to develop a model that can be used to characterize landslide susceptibility in map form using logistic regression analysis of an extensive landslide database. A database of landslide activity was constructed using both aerial-photography and field studies. About 19.2% of the selected study area is covered by deep-seated landslides. The landslides that occur in the area are primarily located in sandstones with interbedded permeable and impermeable layers such as claystone, siltstone and mudstone. About 31.95% of the total landslide area is located at this unit. To apply logistic regression analyses, a data matrix including 37 variables was constructed. The variables used in the forwards stepwise analyses are different measures of slope, aspect, elevation, stream power index (SPI), plan curvature, profile curvature, geology, geomorphology and relative permeability of lithological units. A total of 25 variables were identified as exerting strong influence on landslide occurrence, and included by the logistic regression equation. Wald statistics values indicate that lithology, SPI and slope are more important than the other parameters in the equation. Beta coefficients of the 25 variables included the logistic regression equation provide a model for landslide susceptibility in the Cekmece area. This model is used to generate a landslide susceptibility map that correctly classified 83.8% of the landslide-prone areas.  相似文献   

Landslide susceptibility mapping in the Damrei Romel area, Cambodia using frequency ratio and logistic regression models   总被引：24，自引：0，他引：24  

Saro Lee  Touch Sambath 《Environmental Geology》2006,50(6):847-855

This study applied, tested and compared a probability model, a frequency ratio and statistical model, a logistic regression to Damre Romel area, Cambodia, using a geographic information system. For landslide susceptibility mapping, landslide locations were identified in the study area from interpretation of aerial photographs and field surveys, and a spatial database was constructed from topographic maps, geology and land cover. The factors that influence landslide occurrence, such as slope, aspect, curvature and distance from drainage were calculated from the topographic database. Lithology and distance from lineament were extracted and calculated from the geology database. Land cover was classified from Landsat TM satellite imagery. The relationship between the factors and the landslides was calculated using frequency ratio and logistic regression models. The relationships, frequency ratio and logistic regression coefficient were overlaid to make landslide susceptibility map. Then the landslide susceptibility map was compared with known landslide locations and tested. As the result, the frequency ratio model (86.97%) and the logistic regression (86.37%) had high and similar prediction accuracy. The landslide susceptibility map can be used to reduce hazards associated with landslides and to land cover planning.  相似文献   

Evaluation and Prediction of the Swelling Characteristics of Nigerian Black Clays     

C. M. O. Nwaiwu  I. Nuhu 《Geotechnical and Geological Engineering》2006,24(1):45-56

The swelling characteristics of black clays from two major areas of occurrence in Borno State, Nigeria, were investigated in the laboratory. Clay samples derived from lagoonal clay deposits showed high swelling tendencies while those samples derived from Olivine basalts showed medium to high swelling tendencies. Although interparticle swelling was the dominant swelling mechanism, soil samples with higher clay contents exhibited higher swelling tendencies. The developed predictive models show that the free swell percentage as well as the swelling pressure can be predicted from measured values of electrical conductivity, specific gravity, clay content and plasticity index. On the other hand, swell percent can be predicted from measured values of electrical conductivity and specific gravity only.  相似文献   

用有限元插值法计算区域重力异常     

XIAO Feng MENG Ling-shun College of GeoExploration Science  Technology  Jilin University  Changchun  China 《吉林大学学报(地球科学版)》2006,(Z2)

有限元插值法利用区域边界上的少量数据可计算区域重力异常。由于只有区域数据参与插值计算,其结果更准确。通过教学模型实验得出结论:在区域场近似二次或三次曲面的条件下,有限元插值法比最小二乘法计算的区域场更接近真实值。在某盆地的重力资料处理中,用有限元插值法分离出该区的局部重力异常.  相似文献   

Modern chemometric data analysis – methods for the objective evaluation of load in river systems     

Corinna Kowalik  Jürgen W. Einax 《洁净——土壤、空气、水》2006,34(5):425-436

Environmental data are highly variable. They also include uncertainties resulting from all steps of the analytical process e. g. sampling, or sampling pre‐treatment. However, a lot of information is unfortunately often lost because only univariate statistical methods are used for data evaluation and interpretation. This neglects correlation between different pollutants and relationships among various sampling points. It is therefore necessary to apply additional methods of analysis that can accommodate such relationships. This ability is provided by the established, and by the more modern, multivariate statistical methods because they can analyze complex sets of multidimensional data. These methods are used to visualize large amounts of data and to extract latent information (e. g. differently polluted areas, dischargers, or interactions between different environmental compartments). The goal of this paper is to present the use of established statistical techniques, like cluster or factor analysis, and the progress made in basic modern techniques (e. g. cluster imaging, multiway‐partial least squares regression, projection pursuit, or information theory) and to demonstrate each with examples and illustrations.  相似文献   

3-D Simulation of Tectonic Loading at Convergent Plate Boundary Zones: Internal Stress Fields in Northeast Japan     

Chihiro Hashimoto  Mitsuhiro Matsu'ura 《Pure and Applied Geophysics》2006,163(9):1803-1817

The evidence of east-west compression in northeast Japan has been reported by many investigators on the basis of geodetic, geologic and geomorphic data, but its origin still remains far from understood. In the present study we have proposed a mechanical model of tectonic loading at convergent plate boundary zones, and demonstrated its validity through the numerical simulation of internal stress fields in northeast Japan with realistic 3-D geometry of plate interfaces. At convergent plate boundary zones, in general, a part of plate convergence is consumed by steady slip along plate interfaces, and the remaining part by inelastic deformation (seismic faulting, aseismic faulting, and active folding) of overriding plates. Such a plate boundary process to be called ``partial collision' can be quantitatively described by introducing a collision rate defined as c = 1 − steady slip rate at plate interfaces/plate convergence rate. By this definition, we can simply represent the mechanical process of partial collision, which includes total subduction (c = 0) and total collision (c = 1) as two extreme cases, in terms of steady slip rates at plate interfaces. On the basis of elastic dislocation theory, first, we numerically computed the internal stress fields in northeast Japan produced by the total subduction of the Pacific plate beneath the North American plate, however the computed stress pattern was opposite in sense to observations. Then, we computed the internal stress fields by taking c = 0.1 on average, and succeeded in reproducing the observed east-west compression in northeast Japan. This indicates that the concept of partial collision is essential to understand the mechanism of intraplate tectonic loading.  相似文献