省级气象业务宽带信息网络构建策略

根据目前省级气象部门业务发展需求,结合当地电信行业的发展状况,提出一种可持续发展的宽带网络构建方案.     

Self‐similar solution of a plane‐strain fracture driven by a power‐law fluid

This paper analyses the problem of a hydraulically driven fracture, propagating in an impermeable, linear elastic medium. The fracture is driven by injection of an incompressible, viscous fluid with power‐law rheology and behaviour index n?0. The opening of the fracture and the internal fluid pressure are related through the elastic singular integral equation, and the flow of fluid inside the crack is modelled using the lubrication theory. Under the additional assumptions of negligible toughness and no lag between the fluid front and the crack tip, the problem is reduced to self‐similar form. A solution that describes the crack length evolution, the fracture opening, the net fluid pressure and the fluid flow rate inside the crack is presented. This self‐similar solution is obtained by expanding the fracture opening in a series of Gegenbauer polynomials, with the series coefficients calculated using a numerical minimization procedure. The influence of the fluid index n in the crack propagation is also analysed. Copyright © 2002 John Wiley & Sons, Ltd.     

神经网络专家系统外壳

神经网络专家系统外壳软件,是用于帮助用户迅速开发直观图形解释的人工智能业务应用系统。它以直观的屏幕树图为媒介,实现了正、反向推理机、语义网络、神经元网络、框架结构、知识库管理和算术表达式树图等整体宏观统一;实现了专家系统与人工神经元网络、定性分析与定量计算的统一;无监督分类与监督分类的统一。因此,它的应用范围很广。     

Advances in Numerical Modeling of Astrophysical and Space Plasmas

Advances in the simulation of astrophysical and cosmic plasmas are the direct result of advances in computational capabilities, today consisting of new techniques such as multilevel concurrent simulation, multi-teraflop computational platforms and experimental facilities for producing and diagnosing plasmas under extreme conditions for the benchmarking of simulations. Examples of these are the treatment of mesoscalic plasma and the scaling to astrophysical and cosmic dimensions and the Accelerated Strategic Computing Initiative whose goal is to construct petaflop (10¹⁵ floating operations per second) computers, and pulsed power and laser inertial confinement plasmas where megajoules of energy are delivered to highly-diagnosed plasmas. This paper concentrates on the achievements to date in simulating and experimentally producing plasmas scaled to both astrophysical and cosmic plasma dimensions. A previous paper (Part I, Peratt, 1997) outlines the algorithms and computational growth.     

On the possibility of investigation of the magnetic field structure in subphotospheric layers of the Sun according to observations of sunspot torsional oscillations

A method of investigation of the magnetic field structure in subphotospheric layers of the Sun has been developed. The method is based on observations of the torisonal oscillations of single sunspots. Characteristics of the torsional oscillations have been obtained from observations of the longitudinal magnetic field and radial velocities of seven single sunspots in the photospheric line Fe I λ5253 Å. The parameters of the torsional oscillations and magnetic tubes in the deep layers have been determined. The radius of the cross section of a magnetic flux tube forming a sunspot is greatest near the Sun’s surface and is approximately equal to the radius of a sunspot umbra. Down to the deeper layers, it decreases quite quickly. The longitudinal electric current appearing in the magnetic tube changes direction. The typical time of the current changes is determined by the period of the torsional oscillations. The intensity of the longitudinal magnetic field in the tube increases with depth. The Alfven wave velocity averaged over the length of a magnetic tube is tens or hundreds of times less than this velocity in a sunspot umbra. It decreases with an increase in the period of oscillations. A decrease in the Alfven wave velocity leads to an increase in the twisting angle of magnetic field lines.     

CVN硬盘系统和软件相关处理在e-VLBI试验中的应用

介绍了中国VLBI网（CVN）的e-VLBI技术研究进展．CVN包括上海佘山、乌鲁木齐南山2个固定观测站和云南昆明的流动站，以及上海天文台的2台站硬件相关处理机。2003年上海天文台自行研制了基于PC技术的VLBI数据记录、回放系统，命名为CVN硬盘系统，并成功将其安置于CVN观测站和处理机系统。硬件处理机经过改造后，已能处理来自硬盘和原有磁带系统的数据．从2003年至今，中国VLBI网采用该硬盘系统进行了多次VLBI观测和e-VLBI试验。在CVN硬盘系统基础上，软件相关处理技术的研究也得以开展。软件相关处理原型程序已经被用于台站条纹检测、卫星条纹搜索和数据处理中。该软件获得的计算结果被成功用于国内第一个3台站卫星VLBI的延迟和延迟率闭合试验，以及国内首次利用VLBI数据进行的卫星定轨试验。除此之外，该软件还用作硬件处理机的条纹引导器。为适应未来“嫦娥”月球探测工程，CVN将扩展成含有4个观测站和2个相关处理机（硬件、软件）的实时VLBI网。今后，e-VLBI将被应用于月球卫星导航以及测地和天体物理的VLBI观测。     

水污染物浓度的神经网络预测模式及效果检验

污染物浓度预测是环境保护的重要内容,将神经网络用于水中有机污染物浓度的预测并对效果进行检验.结果表明,预测值与观测值符合较好.     

BP神经网络在矿产资源评价中的应用

简述BP神经网络的基本原理,通过实例阐述BP神经网络在矿产资源GIS评价应用方法,提出注意事项及如何提高评价应用效果.     

基于ArcEngine的管线系统的实现

城市综合管网是城市建设的重要组成部分,随着城市地理空间基础框架工程的推进和城市管网信息化的加速发展,城市管网数据将更加与基础地理数据融合为一体,并为城市建设提供基础服务。结合实际应用,介绍了Ar-cEngine在城市管线管理中的应用,以及管线数据库和基础地理空间框架库集成,对于基于GIS的综合管线系统开发具有借鉴和参考价值。     

GPS参考站网络的多路径误差建模技术研究

通过研究多路径误差的周日重复性特征,将参考站网络多路径历史数据用于减弱参考站网络基线解算中的多路径效应影响,以提高网络解算(尤其指低高度角卫星和新升卫星)的初始化进程及可靠性。通过分析多路径误差的产生机理,研究多路径误差与信噪比信息的强相关关系,建立信噪比相关网络内插模型(SNRIM),用于流动用户位置高精度多路径改正数的实时计算。最后通过四川GPS观测网络实验,验证上述方法在网络高精度实时定位领域应用的有效性及可靠性。