改进异步电机直接转矩控制系统的仿真研究

本文介绍了直接转矩控制系统的控制原理,并针对基于直接转矩控制的异步电动机运行时存在较大的电流及转矩脉动问题,提出一种新的控制方案,并基于Matlab 6.5对这种新方法进行仿真,仿真结果表明该方案能有效的解决电流及转矩脉动的问题.     

Matrix unit cell scheduler (MUCS) for input-buffered ATM switches

This paper presents a novel matrix unit cell scheduler (MUCS) for input-buffered asynchronous transfer mode (ATM) switches. The MUCS concept originates from a heuristic strategy that leads to an optimal solution for cell scheduling. Numerical analysis indicates that input-buffered ATM switches scheduled by MUCS can utilize nearly 100% of the available link bandwidth. A transistor-level MUCS circuit has been designed and verified using HSPICE. The circuit features a regular structure, minimal interconnects, and a low transistor count. HSPICE simulation indicates that using 2-μm CMOS technology, the MUCS circuit can operate at clock frequency of 100 MHz     

Mathematical modelling of surface segregation in aluminum DC casting caused by exudation

A mathematical model for the development of a segregated layer of exudated droplets during DC casting of aluminum ingots is established. The model accounts for the metallostatic pressure driven interdendritic melt flow through the mushy zone by a Darcy type equation, the surface segregation due to this melt flow, and the decrease of the total solute concentration in different positions of the mush as a result of the exudation. The solution domain for the governing differential equations is constituted by the mushy zone of the cast. The main physical phenomena included in the model have been studied in a simple one dimensional case study.     

历史中心区复兴中的地域性问题与对策

本文以上海思南路47～48街坊改造为例,探讨城市形态更新与居民外迁问题,并期待相关地域性社会对策的出现。     

高压变频器在高炉冲渣水泵上的应用

介绍了HARSVERT—A06／035型高压变频器的性能及其在新4号高炉冲渣水泵上的应用。     

Experimental and analytical studies of innovative prestressed concrete box-girder bridges

This paper presents experimental and analytical results of four scaled prestressed concrete box-girder bridges with corrugated steel webs. The location of prestressing strands at both ends of the specimens and the thickness of end diaphragms are the two major parameters. Based on the experimental results of all four specimens, their seismic behavior is critically examined, including hysteretic loops, ductility factor, dissipated energy, and failure mode, etc. It was found that both the thickness of end diaphragms and the location of prestressing strands at both ends of the specimens are insignificant when the specimens failed at the mid-span due to concrete crushing, and the proposed analytical model can be used to predict the load-displacement relationship of such bridges.     

对湖南电信企业文化建设的思考

中国电信南北拆分之后，原有的企业文化并不完全适应新的电信企业，尤其在统一的中国电信的旗号下，湖南电信如何建设有湖湘文化地域特点的企业文化，使之成为湖南电信企业的“灵魂”，本文对此进行了有益的思考，并期待成为抛砖引玉之作。     

空间RSCR四杆机构图解综合法的研究

根据空间RSCR四杆机构出现特殊位置的几何特征,运用旋转变换把空间问题转换为平面问题,对实现两特殊位置运动的空间RSCR曲柄摇杆机构的图解综合法进行了探讨。     

ATM技术浅析

网络通信技术正在迅猛地发展，各种各样的高速通信技术如雨后春笋，其中ＡＴＭ作为一种信元换技术，具有以兆或千兆级速率传送话音、数据和图象的能力，它在网络通信技术中占有特别重要的地位。本文介绍了ＡＴＭ技术的产生、基本特点、体系结构、在ＢＩＳＤＮ中的作用、存在的问题以及发展前景。     

沈阳太平洋广场空调冷热源方案比较

对一幢１１．５万ｍ＾２的四星级综合建筑的空调冷热源不同的蓄冷和取冷比较了四种方案，论证了其中直燃型溴化锂吸收式冷热水机组供冷供暖、小型燃油锅炉供蒸汽的方案最为合理。