Validation and error analysis of a strata modelling technique     

A. D. Mayer  A. K. Isaac  P. Neve 《Geotechnical and Geological Engineering》1984,2(4):305-321

Summary Sources of error are investigated for a two-dimensional finite difference computer program designed to model strata deformation. The program calculates the displacements of a mesh of mass points, by the iterative solution of equations of equilibrium for the stresses acting on each mass point. The effect of errors on both displacement estimates and stress estimates is considered.Round-off errors are discussed analytically, while the effect of choosing too coarse a mesh density is demonstrated by comparison of two runs of the program with identical material properties, but different mesh densities. The influence of boundary conditions and the result of incomplete relaxation of the finite difference equations is estimated by comparison with Kirsch's analytical solution for a thin plate of finite width with a circular hole under unidimensional load.As a result of the analysis, estimators for stresses and displacements are derived, which make allowance for some of the sources of error; suitable boundary conditions for first and subsequent runs of the program are proposed; and a convergence criterion for the iterative process is suggested. These results are then applied to simulations of mining situations, together with various refinements of the basic model, such as separation and slip between adjacent strata, and an allowance for failure of material.  相似文献   

Estimating Variogram Uncertainty   总被引：10，自引：0，他引：10  

B. P. Marchant  R. M. Lark 《Mathematical Geology》2004,36(8):867-898

The variogram is central to any geostatistical survey, but the precision of a variogram estimated from sample data by the method of moments is unknown. It is important to be able to quantify variogram uncertainty to ensure that the variogram estimate is sufficiently accurate for kriging. In previous studies theoretical expressions have been derived to approximate uncertainty in both estimates of the experimental variogram and fitted variogram models. These expressions rely upon various statistical assumptions about the data and are largely untested. They express variogram uncertainty as functions of the sampling positions and the underlying variogram. Thus the expressions can be used to design efficient sampling schemes for estimating a particular variogram. Extensive simulation tests show that for a Gaussian variable with a known variogram, the expression for the uncertainty of the experimental variogram estimate is accurate. In practice however, the variogram of the variable is unknown and the fitted variogram model must be used instead. For sampling schemes of 100 points or more this has only a small effect on the accuracy of the uncertainty estimate. The theoretical expressions for the uncertainty of fitted variogram models generally overestimate the precision of fitted parameters. The uncertainty of the fitted parameters can be determined more accurately by simulating multiple experimental variograms and fitting variogram models to these. The tests emphasize the importance of distinguishing between the variogram of the field being surveyed and the variogram of the random process which generated the field. These variograms are not necessarily identical. Most studies of variogram uncertainty describe the uncertainty associated with the variogram of the random process. Generally however, it is the variogram of the field being surveyed which is of interest. For intensive sampling schemes, estimates of the field variogram are significantly more precise than estimates of the random process variogram. It is important, when designing efficient sampling schemes or fitting variogram models, that the appropriate expression for variogram uncertainty is applied.  相似文献   

雪峰山特长隧道平面控制测量基准的建立   总被引：2，自引：0，他引：2  

王守彬  李林  王新洲 《测绘信息与工程》2005,30(1):33-34

介绍了GPS技术应用于雪峰山特长隧道工程平面测量基准建立的方法,分析了GPS控制网的观测质量,并就GPS控制测量误差对隧道横向贯通误差的影响值进行了估算。  相似文献   

再谈测距仪加、乘常数的检验   总被引：3，自引：0，他引：3  

叶晓明  凌模  陈增辉 《测绘信息与工程》2005,30(6):34-36

以理论和数据再次阐明测距仪加、乘常数误差的概念和检定原理,指出了国家测距仪检定规程JJG703-2003的不足。  相似文献   

InSAR系列讲座5:InSAR系统中的误差传播   总被引：3，自引：0，他引：3  

刘国祥 《四川测绘》2005,28(2):92-95

作为InSAR系列讲座的第五篇，本文介绍InSAR高程与形变测量中的误差来源，对主要误差源（干涉相位、基线参数和地形数据）推导出误差传播模型。此外，还将讨论地形数据误差对干涉形变测量的影响。  相似文献   

误差订正在预报集成中的应用研究     

杨松  杞明辉  姚德宽 《气象》2003,29(12):22-24

根据误差的特性，即误差由系统误差和随机误差组成，对保山5月雨量的几种预报方法的预报结果进行分析，寻找系统误差的订正方法，降低系统误差的影响。将几种预报方法订正后的结果平均从而消除随机误差，其预报结果明显改善，平均误差和均方根误差明显降低，预报准确率明显提高，可以在业务预测中广泛推广应用。  相似文献   

测量误差与不确定度   总被引：1，自引：0，他引：1  

许耿然 《测绘信息与工程》2003,28(2):6-8

主要介绍了误差与不确定度概念的区别和联系，并通过实例对不确定度各分量进行分析、合成和计算，初步探讨了不确定度的评定与表示步骤及方法。  相似文献   

地基GPS大气可降水分全误差分析     

章红平  刘焱雄  唐卫明  王敏 《测绘信息与工程》2003,28(2):11-13

介绍了地基GPS求解大气可降水分的原理及其相关的公式，推导出了其精度评定公式，估计了用GPS观测数据反解GPS信号对流层天顶方向延迟的精度，分析了影响其估计精度的主要因素。  相似文献   

工程测量教学中误差基本概念的应用     

杨昭利 《测绘与空间地理信息》2003,26(2):63-64

主要分析了工程测量教学中误差基本概念的应用,描述了偶然误差和闭合差等概念,举出了教学中的一些例子。  相似文献   

Trimble 5700卫星定位仪在油田井位勘定中的应用     

刘霞 《全球定位系统》2003,28(3):37-41

本文主要介绍了Trimble 5700测地型卫星定位仪的主要性能、在油田井位勘定中的应用及其软件数据处理统计分析。  相似文献