A Connectivity Index for Discrete Fracture Networks

Connectivity is an important measure for assessing flow transport in rock, especially through fractures. In this paper, rock fracture systems are modelled by a discrete fracture model simulated by a marked point process. A connectivity index is then introduced to quantify the connectivity between any two points in space. Monte Carlo simulation is used to evaluate the connectivity index for stationary cases and relationships between the connectivity index and the parameters of the discrete fracture model are analysed. The average number of intersections per fracture, X_f, and the fracture intensity, P12 (P32), are calculated and the relationships between these parameters and the connectivity index are investigated, concluding that X_f is the more suitable parameter for the classification of rock mass flow properties. The relationships between the connectivity index and the percolation state of the fractured medium are also discussed. An edge correction is briefly discussed and a practical example is used to demonstrate the method of computing the connectivity index.     

GPS高程拟合的方式及可靠性分析

在范围不大的区域中，高程异常具有一定的几何相关性，GPS高程拟合就是利用这一原理，求解正常高。在解析法求解过程中，首先用最小二乘法确定拟合数学模型的系数，在此基础上计算出待测点的高程异常值。通过实例验证：GPS高程拟合的精度主要取决于GPS大地高的精度、重合点正常高的精度、重合点的分布及拟模型的选择。一般在重合点数量充足且分布均匀的情况下，GPS高程拟合的精度可达到四等水准网的精度要求。     

A Solution to the Problem of Predicting the Suitability of Silty–clayey Materials for Cement-stabilization

Major geotechnical problems in construction involving silty–clayey soils are due to their low strength, durability and high compressibility of soft soils, and the swell–shrink nature of the overconsolidated swelling soils. Confronted with these problems, a suitable ground improvement technique is needed, for deep excavations in soft clays, for stability, durability and deformation control. Cement-stabilization is one of the alternatives. An increase in strength and durability, reduction in deformability are the main aims of this method. Conventional cement-stabilization methods are used mainly for surface treatment. However, the use of cement has recently been extended to a greater depth in which cement columns were installed to act as a type of soil reinforcement (deep cement–soil mixing and cement jet grouting). In situ engineering properties of these silty–clayey soils are often variable and difficult to predict. For this reason cement-stabilization methods have a basic target to control the aforementioned engineering properties of these clays so that the properties of a silty–clayey soil become more like the properties of a soft rock such as clayey shale or lightly cemented sandstone. So cement-stabilization of these soils is essential to control their engineering properties and to predict their engineering behaviour for construction. In an effort to predict, classify and study the suitability of silty–clayey soils for cement-stabilization both slaking and unconfined compressive strength tests were carried out on clayey–sand mixtures consisted of two types of clays, kaolin and bentonite. Finally diagrams were prepared to study the variation of slaking and strength due to compaction, curing time and cement percentage and also to predict areas of efficient cement-stabilization.     

利用激光强度信息分类激光扫描测高数据

三维机载激光扫描测高数据中不仅含有每个激光脚点的位置和高程信息，而且越来越多的系统同时能提供激光脚点回波信号的强度信息。不同反射面介质对激光信号的反射特性不一样．用实测的数据对激光回波信号的强度信息进行统计标定，并基于标定结果．实现了联合激光强度信息和高程信息进行分类的算法．获得了较为满意的结果。     

基于高光谱卫星遥感数据的UPDM分析方法

提出了一种用于处理多高光谱卫星数据的UPDM分析方法。研究结果证明．该方法应用干Landsat／TM(ETM^-)、Terra／MODIS和ADEOS—II／GLI等高光谱卫星传感器时．光谱重构均方根误差小于0．029适用于研究高光谱卫星遥感数据。     

关于国土资源数据共享分类的思考

数据共享分类是制定数据共享政策和数据资源开发利用规划的一项基础性工作。本文 提出国土资源数据共享分类的意义、原则和方法,探讨建立以数据共享分类为核心的 国土资源数据分类体系,以期为全面开展国土资源数据共享分类提供参考。     

Practical Research of IKONOS-2 Geopositioning and Its Accuracy in Tibet of China

This paper presents the studies of the refining of IKONOS-2 RPC, the transform of the datum, the mode of the control point distribution and the method of IKONOS stereo triangulation, so that IKONOS imagery can be used to collect the precise geospatial data and produce the large scale map. The transform between the IKONOS-2 image space and the national coordinate system based on the RPC have been developed, and the results of block adjustment with various control schemes in a practical project near Himalayas have been examined and analysed. The encouraging results of high positioning accuracy have been obtained.     

GIS中直线元内插点精度及对误差带的影响

基于误差传播定律，考虑参数r误差影响，推导了线元内插点的精度计算公式，讨论内插点精度对线元误差带的影响，并对影响的结果进行了分析，得到了一些有益的结论。     

基于点重要度的地形LOD简化算法及精度

在分析、讨论目前关于3维地形模型简化与误差控制方法的基础上,提出了一种基于点重要度进行连续LOD模型简化的算法.并以5种典型地貌的实验数据作为运行实例,给出了点重要度与地貌类型之间的精度关系.这为今后连续LOD模型的合理建立提供了一种新思路和方法,也为模型的简化提供了科学依据.     

基于高分辨率遥感影像分类的地图更新方法

提出了一种在对遥感影像分类的基础上进行地图更新的方法，讨论了利用高分辨率遥感影像，通过不同空间分辨率和光谱分辨率的影像进行融合，利用合适的高通滤波对影像进行边缘检测．构建一个三层的MLP分类器对影像进行分类，提取城市建筑物与道路信息．并在此分类基础上通过对现有地图的叠加来实现地图的更新。实验结果表明，基于影像融合，利用较少数量的训练样本也能生成具有较高精度的分类图，利用分类结果图进行地图更新能取得令人满意的效果。