话音ATM交换的实现─—ATM论坛电路仿真系列建议

近年来，随着ATM主干网络的建设和发展，研究ATM对现有通信业务的支持方式和适配技术是目前ATM技术研究的热点之一。话音ATM交换在降低话音通信成本和简化网络操作环境等方面提供了大量的技术手段，并且支持在单一网络环境中的多种综合业务传输。ATM论坛制定了电路仿真系列建议，话音ATM交换的技术已经基本成熟。文章通过对话音ATM交换在实现和优化方面的技术进行分析，并提出一种基于NativeModeATM的话音通信方式。     

殷钢荫罩彩管用弹簧片的设计及试验

本文离殷钢荫罩彩色显像管拚接式双金属弹簧片的设计及试验，确定了该管型的整管结构设计。     

有线电视新型业务发布架构研究

本文对现有的有线电视业务发布系统进行了介绍,指出了现有系统的特点,并结合现有系统的分析提出了一种新型的业务发布架构：基于UCL标引的大规模并行数据广播系统.该系统源自李幼平院士的第五传媒的思想,即结合互联网（第四传媒）和电视广播网（第三传媒）的优点,取数字广播作信道,采用“细水长流”的小通道把网站内容整体推送到家,并以先进、廉价的存储技术整合“两大传媒”,通过家庭机顶盒内“镜像存储”自由取用.它继承前两种传媒的长处,又避免了各自短处,是一种全新的文化工具.这应是未来业务发布系统的方向.     

交流传动机车牵引变流器的设计与控制

交流传动电力机车牵引变流系统的特点,本文提出了大功率变流器集成箱设计概念,研究了牵引变流器集成箱设计技术。程集成箱的设计中,从机械强度、怛电距离、低感母排、电磁兼容、散热管理和维护便利几个方面,探究了变流器工作可靠性相关的结构布局和功能部件易于装拆的机电接口设计。牵引变流器控制策略考虑不周不仪能引起外部电网和牵引变流器之间到振荡,电能引输出电机到端部过电压和轴承漏电流并加速电机的损坏。本文分析了牵引变流器的控制对系统性能的影响,提出了改善控制策略的具体措施并得到实际结果的证实。     

Old and new from SOR

From the long history of Successive Over Relaxation (SOR) between the end of second world war and today three points are considered: (1) Classical results of Young and Varga are described. (2) It is shown how results on semiiterative methods can be used to derive these classical results in a unifying way and to compare SOR with other iterative methods. (3) In the last 15 years the application of SOR to compute the stationary distribution of a homogeneous Markov chain has been discussed. These results are reported, considering especially the term extended convergence introduced by Kontovasilis, Plemmons and Stewart.     

TCR型SVC中BOD在晶闸管过电压保护的应用

本文介绍了一种新型半导体器件BOD的物理结构及特性,论述了BOD在晶闸管过电压保护应用中的典型电路设计及参数选择,最后通过TCR工程具体实例,给出实验结果。     

Optimal coordination of directional over-current relays using informative differential evolution algorithm

Growing interconnection in distribution system creates new problem for protection engineers. Particularly the design of overcurrent relay coordination in such system is an independent area of research. With the availability of new artificial based optimization algorithm relay coordination research gain a new momentum. Well established artificial based optimization algorithm such as genetic and particle swam optimization are successfully applied for such applications. This paper discusses the application of informative differential evolution algorithm with self adaptive re-clustering technique for selection of TDS and PSM for optimal coordination of directional overcurrent relays. Both continuous as well as discrete version of informative differential evolution algorithm are used for optimization of relay setting. Proper combination of backup relays for each primary relay are identified by using LINKNET graph theory approach. Coordination of directional overcurrent is developed for 9 bus and IEEE 30 bus distribution systems. The aim of problem is to minimize the total operating time of primary relays and eliminate the miscoordination among the primary and backup relay pairs. Discrete types of settings for electromechanical types of relay are also discussed in this paper. Moreover, the relay coordination problem is modified for providing optimal coordination time interval between 0.2 and 0.8 s among all primary and backup relays pairs. The results are compared with hybrid of genetic algorithm – nonlinear programming and sequential quadratic programming. Digsilient power factory software is used for verification of result.     

OTT_TV的直播解决方案

组播技术是OTT电视直播的解决方案之一。首先介绍了OTT TV的发展现状与存在的一些问题,然后介绍了组播的技术要点,同时,根据OTT中直播电视的使用场景,分析了直播电视的技术要求,提出了组播技术应用于直播电视的可行性方案,结果表明该方案运行良好。     

轧机主传动快熔的作用、选型原则及失效对策

绝缘栅双极晶体管IGBT兼有功率三极管（GTR）和场效应管（MOSFET）的优点,在电子技术、电气传动、开关电源等场合有着广泛的应用。实际使用时,由于装置设计和应用时的意外原因,IGBT可能发生短路,急剧增大的集电极电流将造成器件永久性破坏。IGBT过电流的能力极差,快熔很难起到保护作用,因此现代IGBT模块内部一般都...     

OSS/BSS演进——OTT时代运营商新的制高点

为帮助电信运营商在与OTT运营商的竞合中赢得主动权,文章通过分析通讯行业发展趋势,结合OSS/BSS领域的最新技术能力,为运营商指明在OSS/BSS层面需要着力把控的三个重要发展方向:1)提高快速、动态响应用户需求和新商业模式的能力,2)具备与用户、合作方、网络实时交互的能力,3)简单、灵活的OSS/BSS架构体系。