平面监测网的动态滤波

在假定形变区域为分块连续弹性体的基础上,本文提出一个所谓虚拟形变速率参数形变模型,由它的特例可推出常见的单点位移形变模型。之后又讨论和研究了平面监测网的观测数据滤波问题,设计出一个虚拟形变速率参数卡尔曼滤波器,具体做了这几项工作:(1)在所提出的形变模型下,推导出平面监测网的状态方程;(2)解决了初始状态及其方差阵的估计问题;(3)在极大似然的原则下,得到了动态噪声方差阵的逐次修正公式。在对两个模拟网的几种不同方案进行试算之后,本文提出了几点结论和建议。     

Cost-effective network design for groundwater flow monitoring

The extensive use of groundwater resources has increased the need for developing cost-effective monitoring networks to provide an indication of the degree to which the subsurface environment has been affected by human activities. This study presents a cost-effective approach to the design of groundwater flow monitoring networks. The groundwater network design is formulated with two problem formats: maximizing the statistical monitoring power for specified budget constraint and minimizing monitoring cost for statistical power requirement. The statistical monitoring power constraint is introduced with an information reliability threshold value. A branch and bound technique is employed to select the optimal solution from a discrete set of possible network alternatives. The method is tested to the design of groundwater flow monitoring problem in the Pomona County, California.     

BANDPASS FILTERING ANALYSIS WITH GAUSSIAN WEIGHTING FUNCTION IN TWO-DIMENSIONAL FIELDS

This paper examines the response of the bandpass filter with Gaussian weighting function to arbitrarytwo-dimensional fields and proposes a new concept of relative response function.Based on the properties of relative re-sponse function,satisfactory weighting parameters C_1 and C_2 are obtained.By studying two cases,the procedure of us-ing structure function curves to choose the maximum response wavelength is formulated.It is shown that bandpass fil-tering offers some improvements to the analysis and forecast of mesoscale weather processes.     

灰色系统关联度的新模型及其在预测矿体埋深中的应用

首先提出了灰色系统关联度的一个新模型，分析了该模型的性质，其次讨论了应用该模型和关联滤波法预测矿体埋深的问题，然后进行了理论模型试算，证实了本方法的理论效果，最后，指出了新模型的主要优点。     

Conceptual examination of climate–soil controls upon rainfall partitioning in an open-fractured soil II: Response to a population of storms

A simple two-domain bucket model of fractured soil was coupled with a stochastic model of rainfall variability, in order to investigate the climate and soil controls upon the stochastic properties of the triggering of fracture flow and surface runoff, and the partitioning of rainfall between the matrix and fracture domains and surface runoff. Conventionally, soils are regarded as time domain filters between rainfall and hydrological response. This investigation highlights an additional type of threshold filtering especially important in understanding the infiltration behaviour of fractured soils, for which an event-based characterisation of rainfall in modelling is crucial. A priori-definable indices were derived which are capable of describing elements of this threshold filtering, by allowing the statistical properties of fracture flow- and surface runoff-triggering storms (i.e., mean and variance of storm duration, intensity and effective inter-storm period, as well as cumulative partitioning of rainfall), to be inferred directly from average storm and soil properties. Using these indices, the long-term response of fractured soils, including the long-term hydrological importance of fractures, can be estimated without simulation.     

A comparison of single‐run pushover analysis techniques for seismic assessment of bridges

Traditional pushover analysis is performed subjecting the structure to monotonically increasing lateral forces with invariant distribution until a target displacement is reached; both the force distribution and target displacement are hence based on the assumption that the response is controlled by a fundamental mode, that remains unchanged throughout. However, such invariant force distributions cannot account for the redistribution of inertia forces caused by structural yielding and the associated changes in the vibration properties, including the increase of higher‐mode participation. In order to overcome such drawbacks, but still keep the simplicity of using single‐run pushover analysis, as opposed to multiple‐analyses schemes, adaptive pushover techniques have recently been proposed. In order to investigate the effectiveness of such new pushover schemes in assessing bridges subjected to seismic action, so far object of only limited scrutiny, an analytical parametric study, conducted on a suite of continuous multi‐span bridges, is carried out. The study seems to show that, with respect to conventional pushover methods, these novel single‐run approaches can lead to the attainment of improved predictions. Copyright © 2007 John Wiley & Sons, Ltd.     

基于启发式图搜索的遥感影像道路半自动提取

启发式图搜索法用于线状目标识别的原理是：用图结构表示边缘点和边缘段，根据启发函数计算顶点权值，在图的路径上建立相应的代价函数，通过在图中搜索对应的最小代价的通道以找到最优路径。图搜索法是一种全局最优方法，它在受噪声影响较大时效果仍然较好。文中使用了启发式图搜索法（A*算法）实现了道路的半自动跟踪。它的基本思路是：首先利用自适应平滑滤波算子进行道路信息增强，然后对传统的道路数学模型进行了进一步的扩展，突出了对道路几何特性和辐射特性的描述，并依此构建图搜索的代价函数，实现了基于启发式图搜索法A*算法的道路半自动跟踪。经实验证明，该方法进行遥感影像的道路半自动提取效果较好。     

基于自适应四叉树分割的遥感图像压缩算法

遥感图像具有不同于一般图像的特点,针对遥感图像对压缩算法的特殊要求,提出了自适应四叉树分割算法实现图像的分块,以各像块的均值近似表示该像块的灰度值,从而以尺量少的数值获得对原始图像的最佳逼近,再对辐近误差进行自适应分割和基于像块方差的自适应量化,最后对各分量进行Huffman编码.实验表明,本算法能表现出良好的实用性能,比JPEG算法更适用于遥感图像的压缩.     

Deriving rules from activity diary data: A learning algorithm and results of computer experiments

 Activity-based models consider travel as a derived demand from the activities households need to conduct in space and time. Over the last 15 years, computational or rule-based models of activity scheduling have gained increasing interest in time-geography and transportation research. This paper argues that a lack of techniques for deriving rules from empirical data hinders the further development of rule-based systems in this area. To overcome this problem, this paper develops and tests an algorithm for inductively deriving rules from activity-diary data. The decision table formalism is used to exhaustively represent the theoretically possible decision rules that individuals may use in sequencing a given set of activities. Actual activity patterns of individuals are supplied to the system as examples. In an incremental learning process, the system progressively improves on the selection of rules used for reproducing the examples. Computer experiments based on simulated data are performed to fine-tune rule selection and rule value update functions. The results suggest that the system is effective and fairly robust for parameter settings. It is concluded, therefore, that the proposed approach opens up possibilities to derive empirically tested rule-based models of activity scheduling. Follow-up research will be concerned with testing the system on empirical data. Received: 31 January 2001 / Accepted: 13 September 2001     

防震减灾技术系统网络应用中的网络安全

扼要介绍计算机网络安全结构及Internet网络应用中的数据服务。国家防震减灾技术系统网络中心计算机网络的组成及安全。介绍了Internet提供的服务；网络中心与Internet的2个出口以及它提供的DNS、FTP、E－MAIL、WWW等服务。重点介绍网络中心的防火墙安全及防火墙的过滤作用。