Using weights of evidence in the spatial relation between infected snails and geographic factors     

An Zhao  Shuming Bao  Peng Gong 《地球空间信息科学学报》2013,16(3):217-224

Schistosomiasis is a serious public health problem in the middle-lower Yangtze River Basin in China. Study of spatial variation of snail distribution that is related to microgeographic factors can help to choose pertinent measures for snail extinguishment and environment rebuilding. This paper studied the theoretical architecture of weights-of-evidence approach. The case study was made for spatial relation between the occurrence of infected snails and geographic factor combinations in Waijiazhou marshland of Poyang Lake region in China. The multievidence data came from the geographical factor combinations by crossing operation of vegetation coverage grade layer, cattle route distance grade layer, and special environment layer (181 combinations in total) in GIS. The calculation of weight contrast index shows that high vegetation coverage, cattle route distance of <45 meters, and special geographic factor “ground depression” had direct spatial relation with the occurrence of infected snails. The verification by crossing operation in GIS indicated 72.45% of the infected snails concentrated on the areas of positive weight contrast index (sequenced in an order of weight contrast index from high to low), demonstrating the high efficiency of the model established in finding infected snails according to the geographic factor combinations that can be explicitly discerned in the study area.  相似文献   

基于GIS的证据权重法在铀成矿远景预测中的应用——以内蒙古巴音戈壁盆地为例     

张琪  王建国  李必红  李珂 《国外铀金地质》2012,(1):41-46

基于GIS平台,通过对巴音戈壁盆地地质、物探、化探、遥感等多源信息进行综合处理分析,选取了化探铀、航放铀、遥感羟基等15个信息图层,采用证据权重法对研究区进行了铀成矿预测与评价,对预测结果进行分级,圈定了11个铀成矿远景区,取得了较好的效果,提高了研究区成矿预测的精确度与可靠性。  相似文献   

月平均降水量的二次规划最优组合预测方法研究   总被引：6，自引：0，他引：6  

农吉夫  金龙 《热带气象学报》2004,20(6):704-712

以逐步回归、均生函数和多层递阶作为月平均降水量的3种子预报方法，进一步采用二次规划计算方法，通过计算各子方法的最优非负权系数进行最优组合预测建模研究。实例计算结果表明，这种组合预测模型的预报精度优于各子方法，并具有较好的理论依据，可在实际业务预报中进行推广应用。  相似文献   

Measuring the Performance of Mineral-Potential Maps   总被引：2，自引：0，他引：2  

Frederik?P.?AgterbergEmail author  Graeme?F.?Bonham-Carter 《Natural Resources Research》2005,14(1):1-17

D. P. Harris and others have proposed a new method for comparative analysis of favorability mappings. In their approach, Weights-of-Evidence (WofE) consistently shows poorer results than other more flexible methods. Information loss because of discretization would be a second drawback of WofE. In this paper, we discuss that the random cell selection method proposed by Harris and others necessarily results in higher success ratios for more flexible methods but this does not necessarily indicate that these methods provide better mineral-potential maps. For example, a good point density contouring method that does not use any geoscience background information also would score high in the random cell selection approach. Additionally, we show that discretization usually is advantageous because it prevents occurrences of overly high posterior probabilities. For more detailed comparison, we have conducted a number of experiments on 90 gold deposits in the Gowganda Area of the Canadian Shield comparing WofE with the more flexible weighted logistic regression method. Mineral occurrences should be modeled as discoveries at points instead of randomly sampling them together with their surrounding environments in small cells.  相似文献   

GIS-Based Slope Stability Analysis,Chuquicamata Open Pit Copper Mine,Chile   总被引：1，自引：1，他引：1  

Eric P. Nelson  Katherine A. Connors  Claudio Suárez S. 《Natural Resources Research》2007,16(2):171-190

The risk of slope failure in the Chuquicamata open-pit mine was analyzed using Geographic Information System (GIS) software and modeling techniques. Models incorporated various component layers at a relatively large map scale (1:5000): alteration, geotechnical unit, proximity to major faults (VIF), GSI (geological strength index), slope (from digital elevation model), proximity to watertable (difference grid between topography and modeled watertable), and composite structural density grid (VIF, smaller faults, and fracture frequency); not all layers were used in all models. Three modeling techniques were used: fuzzy logic, in which parameters in each component layer were ranked by mine geotechnical experts according to their influence in promoting slope failure, and two data-driven techniques, weights-of-evidence and logistic regression, in which statistical correlation of training points (known failures) with parameters were used to derive a relative probability of failure. Because most slope failures are controlled by structure, VIF and smaller faults were divided by orientation into subsets with dip direction parallel, opposite, and normal to slope aspect; these orientations promote circular and planar, toppling, and wedge-type failures, respectively. Density grids of these subsets show high-risk areas for individual failure types. The models demonstrate sensitivity of the analysis to (1) selection of component layers, (2) selection of training points, (3) classification and ranking of categorical parameters, and (4) data problems in certain layers. Predicted high-risk zones in the final models show a high degree of correspondence with recent, post-model failures. Such models can be used to anticipate future pit design concerns. The results presented here illustrate how vast amounts of data, in multiple geo-referenced layers, can be analyzed and modeled using GIS techniques for predictive studies at relatively large map scales. Such modeling techniques could provide a powerful tool for predictive modeling in a vast array of large-map-scale applications requiring similar data integration and evaluation.  相似文献   

赫尔默特方差分量估计在混合水准网平差中的应用   总被引：2，自引：0，他引：2  

李希峰  岳东杰  卫柳艳 《现代测绘》2005,28(5):20-22

测量中有些时候会碰到定权不统一的问题,导致了平差后的结果不理想.本文主要讨论的是通过赫尔默特方差估计的方法消除由于定权的不合理而产生的精度超限问题.通过实例进行分析表明,利用赫尔默特方差分量估计在进行迭代定权非常实用,大大提高了其精度.  相似文献   

基于Arc-WofE系统的证据权法在层控型铅锌成矿预测中的应用   总被引：2，自引：0，他引：2  

严冰  阳正熙  王小春 《新疆地质》2005,23(3):300-303

通过分析四川宁南地区层控铅锌矿床成矿特征，建立了基于GIS平台的应用图层数据库，采用Arc-WofE系统进行证据权法模拟预测，划分出13个铅锌成矿远景区．通过对宁南地区现有矿床的分析，认为证据权法数学预测模型对区域成矿远景区于预测有较高的准确性和科学性，同时在和Arc—WofE系统结合后，可对多源信息进行空间位置综合处理并形成新的综合变量，能更全面、客观的反映地质体空间特征，使成矿预测更加准确．  相似文献   

吉林市经济技术开发区场地稳定性分区与评价     

徐德敏  王利刚 《世界地质》2001,20(1):84-89

在对吉林经济技术开发区工程地质概括地描述，分析的基础上，选取地面披度，切割深度，冲沟长度，卵砾石埋深，地下水埋深，平均剪切波速，负5m切面岩性和断层性质为评价因子，利用模糊综合评判的方法，对场地稳定性进行分区和评价，并在权重的选取上提出一种新的思路。  相似文献   

大吨位堆载法对单桩承载力试验的影响     

袁从华  章光 《岩土力学》1997,18(1):78-83

大吨位堆载法对单桩承载力试验结果存在四个方面的影响，分别对它们进行了理论分析，并对它们的影响程度进行了评估。  相似文献   

Spatial declustering weights   总被引：1，自引：0，他引：1  

G. Bourgault 《Mathematical Geology》1997,29(2):277-290

Because of autocorrelation and spatial clustering, all data within a given dataset have not the same statistical weight for estimation of global statistics such mean, variance, or quantiles of the population distribution. A measure of redundancy (or nonredundancy) of any given regionalized random variable Z(u_α)within any given set (of size N) of random variables is proposed. It is defined as the ratio of the determinant of the N X Ncorrelation matrix to the determinant of the (N - 1) X (N - 1)correlation matrix excluding random variable Z(u_α).This ratio measures the increase in redundancy when adding the random variable Z(u_α)to the (N - 1 )remainder. It can be used as declustering weight for any outcome (datum) z(u_α). When the redundancy matrix is a kriging covariance matrix, the proposed ratio is the crossvalidation simple kriging variance. The covariance of the uniform scores of the clustered data is proposed as a redundancy measure robust with respect to data clustering.  相似文献