多路隔离输出全数字伺服系统开关电源设计

根据设计全数字永磁交流伺服系统的需要,使用Power Integration公司生产的开关电源专用集成芯片TOP224Y,设计了单端反激式多输出辅助开关电源。使用该芯片设计的小功率开关电源,可大大减少外围电路,降低成本,提高可靠性,同时,可以改善电源的电磁兼容性能。重点论述了开关电源的电路设计及高频变压器的设计。本辅助电源稍经改动也可以直接用在其他电机控制系统中。     

幂等矩阵的多项式的极小多项式的算法

利用二元多项式的理想的简化Groebner基的算法，建立了一种判定幂等矩阵的二元多项式可逆性的有效方法，并提出求其极小多项式及其逆矩阵的一种算法，这一算法可由代数系统软件CoCoA4．1来实现。     

高效紧凑的高频地波雷达天线阵列设计

分析了高频地波雷达阵列单元天线和阵列的设计原理,提出并成功设计出了一套高效紧凑、一发八收、收发共用的高频地波海洋环境监测雷达天线阵列.计算机模拟和现场试验结果说明了本文设计方案的合理性.     

一种WWW搜索引擎的设计与实现

随着Internet在我国的迅速发展和WWW信息的不断增长,迫切需要开发中英文兼容的WWW搜索引擎来获得所需的信息。该文在分析WWW搜索引擎主要功能模块:信息采集模块、信息预处理模块和信息查询模块的基础上,提出采用人工智能搜索算法来遍历网页,对中英文网页进行自动的索引,并用向量空间的表示方法来表示网页内容和用户输入的查询表达式。实践证明,使用该搜索引擎,可以快速准确地搜索到用户所需的信息。     

数字PWM方法的改进

数字化PWM调制在高频应用中存在精度受限制的问题，本文提出一种新的PWM技术——双调制PWM，结合高频和低频的优势，解决了数字化PWM中高频与精度之间的矛盾，使数字化PWM可用于高频、高精度电能变换器之中，理论分析、仿真和实验结果均论证了这一方法的优越性。     

一种便携式多功能测量仪

介绍用８０９８单片机为核心组成的便携式多功能测量仪。该仪器采用模块式插入技术实现了多功能测量，利用软件修正误差技术提高了仪器的测量准确度，使之具有较高的性能价格比，特别是高频电压实现了数字化测量，且通过频响误差修正达到了较高的准确度。该仪器的研制成功对设计制造具有中国特色的电子测量仪器有一定的参考价值。     

The Eigenvalue Problem for the 2D Laplacian in ℋ-Matrix Arithmetic and Application to the Heat and Wave Equation

A class of matrices (-matrices) has recently been introduced by Hackbusch for approximating large and fully populated matrices arising from FEM and BEM applications. These matrices are data-sparse and allow approximate matrix operations of almost linear complexity. In the present paper, we choose a special class of -matrices that provides a good approximation to the inverse of the discrete 2D Laplacian. For these 2D -matrices we study the blockwise recursive schemes for block triangular linear systems of equations and the Cholesky and LDL^T factorization in an approximate arithmetic of almost linear complexity. Using the LDL^T factorization we compute eigenpairs of the discrete 2D Laplacian in -matrix arithmetic by means of a so-called simultaneous iteration for computing invariant subspaces of non-Hermitian matrices due to Stewart. We apply the -matrix techniques to approximate the solutions of the high-frequency 2D wave equation for smooth initial data and the 2D heat equation for arbitrary initial data by spectral decomposition of the discrete 2D Laplacian in, up to logarithmic factors, optimal complexity.     

Keywords in communications technology

New communications products are often described by their manufacturers using a variety of confusing keywords, such as teletex, videotex, network integration etc. The manufacturers do not, however, explain the relationships between these terms, or the concepts that they share. The paper discusses these keywords with respect to the ISO reference model for open systems interconnection, and their relative positions within this structure. It discusses, in detail; transmission, switching, internetworking, network integration, local area networks and integrated service digital networks. Keywords relating to applications such as office automation and text processing are more clearly interrelated, and future end systems are proposed.     

基于中间件技术的RFID通讯组件设计

首先介绍了RFID中间件的概念,接着介绍了通讯组件所处理的数据的封装格式:即某企业的系列高频读写器的通讯协议格式.在此基础上,建立了底层数据通讯接口组件、设备网络接口组件、设备参数接口组件、对标签读写操作接口组件、数据库接口组件等五个接口组件的软件设计,最终实现了RFID中间件通讯组件的设计,为第三方的企业级软件应用提供了基础.     

电除尘器电源的发展方向——高频化和数字化

本文以电除尘器电源的发展方向——高频化和数字化为题,从理论和实践上,以作者亲身体验的数据说明了IGBT高频开关电源能克服传统SCR工频相控电源的缺点,能提高除尘效率,采用全数字控制能同时解决电除尘器系统控制问题,从而说明了高频开关电源是典型的环保节能降耗产品,是新建和改造电除尘器的首选供电设备。文章还提供了电除尘器用高频开关电源的线路、控制方案及设计原则。