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81.
为了将不同边界品位情况下矿体的形态及由边界品位变化引起的矿体形态变化程度在计算机中动态、实时地展现,同时也为了解矿体在不同工业指标条件下的空间形态,进行了矿体动态建模方法研究。采用了一种新的、基于矿体属性模型向其几何结构模型转化的方法--克里格块体法。通过该方法,基于指示克里格估值技术,使用块体模型+实体模型的三维数据模型结构,动态地构建出了福建上杭紫金山铜金矿矿体在不同边界品位条件下、信息充分、完备且具高可信度的矿体模型,达到了使建模结果能够真正服务于矿山勘探和生产实践的效果。该方法具有一定的可扩展和易推广的性质,能够完成大多数类似矿山及类似地质体的动态建模过程。  相似文献   
82.
The analysis of health data and putative covariates, such as environmental, socio-economic, behavioral or demographic factors, is a promising application for geostatistics. However, it presents several methodological challenges that arise from the fact that data is typically aggregated over irregular spatial supports and consists of a numerator and a denominator (e.g., population size). This paper presents an overview of recent developments in the field of health geostatistics, with an emphasis on three main steps in the analysis of areal health data: (1) estimation of the underlying disease risk, (2) detection of areas with significantly higher risk, and (3) analysis of relationships with putative risk factors. The analysis is illustrated by using age-adjusted cervix cancer mortality rates recorded from 1970 to 1994 of 118 counties in four Western USA states. Poisson kriging allows the filtering of noisy mortality rates computed from small population sizes, enhancing the correlation with two putative explanatory variables: percentage of habitants living below the federally defined poverty line, and percentage of Hispanic females. Area-to-point kriging formulation creates continuous maps of mortality risk, reducing the visual bias associated with the interpretation of choropleth maps. Stochastic simulation is used to generate realizations of cancer mortality maps, which allows one to quantify how uncertainty of the spatial distribution of health outcomes translates into uncertainty of the location of clusters of high values or the correlation with covariates. Finally, geographically-weighted regression highlights the non-stationarity in the explanatory power of covariates; the higher mortality values along the coast are better explained by the two covariates than the lower risk recorded in Utah.  相似文献   
83.
《水文科学杂志》2013,58(4):700-712
Abstract

The groundwater flow equation governing the elevation (h) of the steady-state phreatic surface in a sloping aquifer fed by constant recharge over a bi-circular sector is rhh′ ? r 2 Bh′ + Pr 2 ? PR 2 = 0, where r is the radial coordinate, P is a constant involving recharge and aquifer properties, and B is the slope of the aquifer—bedrock boundary. The derived flow equation describes radially convergent flow through a sloping aquifer that discharges to a water body of fixed head. One important simplification is that in which the width of the bi-circular sector is constant, and the draining land becomes a rectangular aquifer. The bi-circular sector and rectangular-strip groundwater flow problems are solved in terms of implicit equations. The solutions for the steady-state phreatic surfaces depend on the ratio of recharge to hydraulic conductivity, the slope of the aquifer-bedrock, and the downstream constant-head boundary. Computational examples illustrate the application of the solutions.  相似文献   
84.
Downscaling has an important role to play in remote sensing. It allows prediction at a finer spatial resolution than that of the input imagery, based on either (i) assumptions or prior knowledge about the character of the target spatial variation coupled with spatial optimisation, (ii) spatial prediction through interpolation or (iii) direct information on the relation between spatial resolutions in the form of a regression model. Two classes of goal can be distinguished based on whether continua are predicted (through downscaling or area-to-point prediction) or categories are predicted (super-resolution mapping), in both cases from continuous input data. This paper reviews a range of techniques for both goals, focusing on area-to-point kriging and downscaling cokriging in the former case and spatial optimisation techniques and multiple point geostatistics in the latter case. Several issues are discussed including the information content of training data, including training images, the need for model-based uncertainty information to accompany downscaling predictions, and the fundamental limits on the representativeness of downscaling predictions. The paper ends with a look towards the grand challenge of downscaling in the context of time-series image stacks. The challenge here is to use all the available information to produce a downscaled series of images that is coherent between images and, thus, which helps to distinguish real changes (signal) from noise.  相似文献   
85.
Analyzing temporal trends in health outcomes can provide a more comprehensive picture of the burden of a disease like cancer and generate new insights about the impact of various interventions. In the United States such an analysis is increasingly conducted using joinpoint regression outside a spatial framework, which overlooks the existence of significant variation among U.S. counties and states with regard to the incidence of cancer. This paper presents several innovative ways to account for space in joinpoint regression: (1) prior filtering of noise in the data by binomial kriging and use of the kriging variance as measure of reliability in weighted least-square regression, (2) detection of significant boundaries between adjacent counties based on tests of parallelism of time trends and confidence intervals of annual percent change of rates, and (3) creation of spatially compact groups of counties with similar temporal trends through the application of hierarchical cluster analysis to the results of boundary analysis. The approach is illustrated using time series of proportions of prostate cancer late-stage cases diagnosed yearly in every county of Florida since 1980s. The annual percent change (APC) in late-stage diagnosis and the onset years for significant declines vary greatly across Florida. Most counties with non-significant average APC are located in the north-western part of Florida, known as the Panhandle, which is more rural than other parts of Florida. The number of significant boundaries peaked in the early 1990s when prostate-specific antigen (PSA) test became widely available, a temporal trend that suggests the existence of geographical disparities in the implementation and/or impact of the new screening procedure, in particular as it began available.  相似文献   
86.
金毅  郑德顺  潘懋  张璐 《地质学报》2011,85(9):1519-1527
矿化作用往往是地质事件及局部过程共同作用的结果,导致矿体空间形态复杂多变、矿石品位呈各向异性、尺度不一的非线性空间变异模式.传统方法无论是在矿石量的计算方面还是在矿块内平均品位的确定上都存在多种误差,并且无法实现信息的动态管理及直观表达.文章以安庆铜矿中心矿区为例,采用对数块kriging与三维地学模拟技术相结合的方法...  相似文献   
87.
运用普通克里格、泛克里格、协同克里格和回归克里格4种方法,结合由DEM获取的高程因子以及土壤全氮和阳离子交换量(CEC),预测了黑龙江省海伦市耕地有机质含量的空间分布。不同样点数量下海伦市土壤有机质含量的空间变异结构分析表明,样点数量多并不一定能够识别土壤有机质含量的结构性连续组分,最优化的布置采样点位置可能比单纯增加...  相似文献   
88.
Theoretical difficulties for mapping and for estimating river regime characteristics in a large-scale basin remain because of the nature of the variable under study: river flows are related to a specific area, i.e. the drainage basin, and are hierarchically organized in space through the river network with upstream-downstream dependencies. Another limitation is there are not enough gauge stations in developing countries. This presentation aims at de-veloping the hydro-stochastic approach for producing choropleth maps of average annual runoff and computing mean discharge along the main river network for a large-scale basin. The approach applied to mean annual runoff is based on geostatistical interpolation proce-dures coupled with water balance and data uncertainty analyses. It is proved by an applica-tion in the upstream at Bengbu in the Huaihe River Basin, a typical large-scale basin in China. Hydro-stochasitic approach in a first step interpolates to a regular grid net and in a second step the grid values are integrated along rivers. The interpolation scheme includes a con-straint to be able to account for the lateral water balance along the rivers. Grid runoff map with 10 km × 10 km resolution and the discharge map along the river with the 1 km basic length unit are the main results in this study. This kind of statistic approach can be widely used be-cause it avoids the complexity of hydrological models and does not depend on the meteoro-logical data.  相似文献   
89.
空间分析中几种插值方法的比较研究   总被引:2,自引:0,他引:2  
针对常用的空间插值方法在精度分析方面比较的不足,从地质统计学、数学函数和几何方法方面分别选取普通克里金插值法、三次样条函数法和距离权重倒数法进行插值精度的比较与分析。文章分析了各个方法的优缺点和局限性,选取疏密差异较大的均匀和不均匀离散点数据进行实验,利用三次趋势面模型和MATLAB,ArcGIS,GS+Version...  相似文献   
90.
近年来我国普通劳动者工资变化及其对农地利用的影响   总被引:10,自引:0,他引:10  
利用农村固定观察点数据、《全国农产品成本收益资料汇编》、全国农业统计数据等,对近年来我国普通劳动者工资的变化特征及其对我国农地利用的影响进行了分析。结果表明:近年来我国普通劳动者工资的增长速度和幅度明显要快于农产品和农业生产资料价格的增长速度。我国东部发达地区的部分省份,其复种指数已经出现了明显的下降趋势,物质和服务投...  相似文献   
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