Finite element computation of shape factors for Kirkham's piezometer tube method for hydraulic conductivity of saturated soil

The Kirkham piezometer tube method of measuring hydraulic conductivity of saturated soil uses a numerical constant (shape factor) to account for the relative geometrical parameters of the cavity and the soil domain. Published shape factors have mostly been determined using an electrical analogue. In this paper the application of the finite element method to shape factor determination is considered. Convergence is studied and methods of extrapolation evaluated. A determination is made of the size of finite region required to represent adequately the radially unbounded domain assumed for the piezometer method. Computed shape factors were found to be in good agreement with analogue data.     

基于形状分析的点状地图符号识别

着重讨论了基于形状分析的点状地图符号识别。其主要内容包括点状地图符号的计算机描述，点状地图符号识别系统的结构，点状地图符号识别实验与分析等。文中利用带搜索控制准则的新边界跟踪算法，改进了传统的边界跟踪算法，提出了用傅立叶系数描述点状地图符号的形状特征，并对计算公式作了进一步改进，介绍如何由傅立叶系数提取形状特征不变量，实现了对点状地图符合的自动识别。     

地籍测量信息处理系统若干问题的探讨

简要介绍了信息时代对地籍信息的要求和地籍信息的拓扑结构，探讨了如何实现地籍测量信息处理系统与GIS系统的无缝结合。     

海底地震数据记录器

海底地震数据记录器是一种大动态、宽频带数字仪器，能用 于海底或陆地边远地区记录地震数据. 它体积小、重量轻、操作简单，采用两个缓存存 储器控制PC/104嵌入式计算机，能在低功耗、长时间连续记录地震数据. 记录器的关键部件 是PC/104嵌入式计算机，能保证记录器工作可靠. 它使用硬盘存储数据，2GB的硬盘能容纳 19998 GB的地震数据，记录地震数据多长时间由抽样率决定.     

测量觇牌的设计与精度分析

通过几种不同形状和色彩的测量觇牌的观测实践，研究了测量觇牌的设计形状、色彩与观测精度的关系等问题。     

数字地图图像特征的形态学分析模型

本文在基本的数学形态学理论和运算的基础上，结合地图图像的连接性、形状、尺度、纹理、拓扑与几何等特征，系统地应用、扩展和提出了描述这些基本图像特征的各种形态学分析模型，构成了数字地图图像形态分析和处理的理论体系。     

形状信息的提取与计算机自动分类

近年来，遥感数据越来越普遍地被利用为更新地理信息系统的数据源。但利用ＧＩＳ来改善分类精度的探讨却很少。本文提出了利用ＯＩＳ技术来提取形状信息和改善分类精度的新方法，从而使一些容易混淆的分类得到纠正。     

Time varying seismicity in Greece: Hurst's analysis and Monte Carlo simulation applied to a new earthquake catalogue for Greece

Hurst's rescaled range analysis is a useful tool in the examination of a time series and is designed to measure memory content and determine its fractal texture. This study applies the Hurst method to a new earthquake catalogue for Greece. The study also adopts Monte Carlo simulations to provide a statistical test underpinning the Hurst analyses. Together these reveal basic temporal fractal characteristics in the earthquake occurrence time-histories' memory. Three regions are considered, approximately: all of Greece and some surrounding areas, and the sub-zones of the Hellenic Arc and the Gulf of Corinth. Three temporal textures are considered: elapsed time between earthquakes, strain energy release, and earthquake frequency. The elapsed temporal textures for the zone whole Greece indicate distinct characteristics in chronological order and possess long memory. These belong to the class non-random pattern. However, these characteristics generally disappear when the sub-zones are considered and become random patterns. The Monte Carlo simulations support this. Therefore, memoryless statistical seismic hazard estimates may not be suitable for whole Greece but could be useful for the sub-zones. The strain energy release temporal textures for whole Greece and for the sub-zones, no matter that these seem to possess long memory at first analysis, are all random patterns. In other words, the Monte Carlo simulations demonstrate that these patterns are much more likely to happen by chance. The seismic frequency textures for whole Greece and for the sub-zones suggest long memory, however, only the texture for the Hellenic Arc zone (M_S ≥ 5.0) and that for whole Greece (M_S ≥ 4.0) approach demonstrable non-random patterns. Except for these, other patterns happen by chance.     

GPS作业过程中的质量控制初探

从GPS作业过程的网形设计、外业观测和基线解算等方面简述了在GPS静态定位测量中影响质量的主要因素,并对网形设计、外业观测和基线解算进行了分析,详细分析了影响GPS基线解算结果的主要因素,给出了判别这些因素方法,并对如何消除这些因素的影响提出了相应的处理措施。     

Laboratory model tests about the sand embankment supported by piles with a cap beam

Piled embankment is widely used in soft soil areas. Most researches focused on effects of embankment height-net pile spacing ratios and equal settlement plane; there are limited publications paying attention to the shape of slip surfaces occurring in the embankment. In some extreme conditions, such as the ground being quite soft or embankment height needed to be restricted, to reduce the differential settlement and lateral displacement, piles are usually installed in several rows and cap beams or isolated caps are placed on the heads of piles. In this paper, five laboratory tests were carried out to investigate the effect of embankment height on the slip surfaces and stress exerted on the subsoil. Based on the observation of the slip surface’s shape within the embankment fill, a new calculation model is proposed to predict the stress exerted on the subsoil. In comparison with the experimental results, the accuracy of this new method is verified. From the perspective of reducing the differential settlement and cost savings, the embankment height is about four times net pile spacing according to this calculation model, since continuing to increase the embankment will not make an obvious difference to the reduction of soil stress exerted on the subsoil.