电缆夹层电缆防火设计与施工

1前言电缆夹层是发电厂、变电所电缆最密集的地方之一,一旦发生火灾,后果则不堪设想。因此,电线夹层是电缆防火的重点部位之一。在SDJ278－90《水利水电工程设计规范》第7．0．1条规定：电缆室动力电缆上下电缆层之间,应装设耐火隔板。第70．7条规定：大型电缆室宜装设固定式水喷雾等灭火系统。在GB50229－96《火力发电厂与变电所设计防火规范》第9．3．3条规定：变电所电缆夹层宜设置悬挂式气体自动灭火装置。2设计与施工的类型目前,我区电缆夹层电缆防火设计和施工有各式各样,归纳起来有下述三种类型。2.1第一种类型除对电缆穿越…     

Cable as choice

The major benefit that cable TV has to offer the UK customer is choice. The question is: should choice be limited in any way? Vested interests in the television and film industry are pressing for restrictions on two ‘no go’ areas-live sport and first release films. Gareth Locksley argues that there is no case for restrictions, and that choice will benefit the television and film industries and the consumer.     

有线电视光缆传输系统指标的分析与设计

介绍了有线电视网中ＡＭ 光缆干线传输综合指标的分析与设计。由于ＤＦＢ激光器间的非线性有较大差异,故引入了光链路这一参数。当把这一参数引入有线电视光缆干线设计时,可根据有线电视光缆系统不同传输距离、光接点的分配指标和光缆干线传输系统的实际情况,计算光链路损耗,以确定光端设备的选型,从而进一步确定光缆干线传输系统的设计,使得有线电视总系统指标给以保证     

小学数学教学中“兴趣”的培养

在课堂教学中,学生的兴趣是跃还是伏,要使兴趣持续,关键在于创设课堂高涨的情绪和氛围,情绪和氛围是可以＂传染＂的,具有影响性。课堂上整体的学习情绪、氛围,可以影响个别学习兴趣不高的学生产生较强的兴趣。儿童学习任何事情最合适的时机是他们的兴致最高时。兴趣是学习的先导,是学生获取知识的一种强烈欲望。在课堂教学中,当教师唤起学生的兴趣之后,学生便会积极主动地去参与教学活动,从而获得教学的最佳效益。     

预应力锚索锚固效果的试验分析研究

通过理论分析锚固段应力分布弹性解和数值模拟计算,表明预紧力、孔径、锚固剂弹性模量和岩石弹性模量等影响因子对锚固段受力影响程度和方面各不相同,例如预紧力和锚固剂弹性模量的影响程度大于其他因子;锚索孔径对其剪应力分布产生影响而对轴力无影响等。锚索轴力和剪应力分布均呈指数关系从锚固端向内逐渐递减,峰值点位于锚固起始端,而锚固段周边剪应力的分布是不均匀的,峰值位于锚固端约0.25m深度内。     

提高电缆下线工艺生产效率的创新设计

本文以中国中车动车生产中的电缆下线工序为研究对象,运用工业工程与TRIZ 创新方法相结合的方式对该工序生产效率进行提升。作者根据现有工艺流程进行作业分割,对分割出的每一步作业进行连续多次测时,将测量数据统计分析得到改进空间大的作业,分别运用目视化管理、视线轨迹追踪等工业工程类的方法进行改善,通过改进挂线架、剪线表和卷线机解决了上述发现的问题。同时,本文对整个系统建立功能模型,通过功能分析找出问题的关键因素, 运用一系列的TRIZ 的工具解决问题。     

Cable television and government policy in Japan

The development of the cable industry in Japan has been steady but slow. The Japanese cable penetration rate is not as high as in the USA and Canada for several reasons, and in this article the focus is on how broadcasting policy in Japan has affected the cable television market. Nevertheless the number of cable television systems has increased every year, and the future of the cable business in Japan is also discussed.     

交流控制回路中不容忽视的电缆电容

针对电缆线芯间的电容电流对交流控制回路的影响，使交流接触器不能复归或出现自行吸合的现象，提出了解决方案，供电气工程技术人员借鉴。     

双绞线网络电缆制作关键

网络连接电缆的质量对于保证网络的整体性能至关重要 ,本文针对双绞线网络电缆制作中必须加以注意的、容易产生错误的关键步骤 ,逐一进行了讲解。     

铜、铝芯电力电缆应用的经济性分析

通过对交联聚乙烯铜芯、铝芯电力电缆的技术参数进行对比分析,指出了铜芯电缆在应用过程中的经济性及应用前景。     

Cable TV in Austria. Between telecommunications and broadcasting

In this paper the development of the Austrian cable television (CATV) sector is discussed, focusing on its delicate interconnections with telecommunications and broadcasting, the blurring borderlines and resulting regulatory problems. The policy network is identified and recent changes in the CATV policy and strategy are highlighted, In particular, developments towards a stronger convergence within the electronic communications sector. The case study illustrates peculiarities and shortcomings of Austrian media and communications policies on the way toward a future-oriented information infrastructure.     

Cable television and competition : Theory, evidence and policy

There is currently widespread discussion in the USA of the merits of amending legislation to allow competition in the cable television market, notably from the telecommunications companies. This article explores what economic theory can contribute to this debate, and adduces empirical evidence on the effects of competition in the cable market where it presently exists. The authors conclude that blocking entry into cable, and indeed into telecommunications markets, is likely to be poor policy, and that increased competition would foster the development of an efficient modern broadband network.     

通信电缆故障测距的小波变换应用研究

在论述电力系统通信电缆故障检测原理的基础上,将小波变换模极大值与信号奇异性关系的理论应用于检测脉冲反射信号,实现电缆故障的定位。重点分析了利用小波变换模极大值的方法实现在强噪声中提取信号,再现信号突变点的功能。仿真表明这种方法能有效去噪、准确定位脉冲反射信号,为提高信道故障定位精度提供了有效的检测方法。     

300k高速电缆传输系统的可靠性设计

在300k高速电缆传输系统的研制过程中首次引入可靠性设计理念，在系统的可靠性设计方面做了大量的、细致的工作，详细阐述了可靠性设计的具体内容和应用效果。     

Sequential Auctions of Interdependent Objects: Israeli Cable Television Licenses

In Israel, area cable television (CATV) licenses were auctioned sequentially. This paper provides evidence that (i) there were interdependencies among many of the franchises and that (ii) subscriber fees for the interdependent franchises decreased over time in this auction.     

Horizontal Concentration and Vertical Integration in the Cable Television Industry

In the recent past, the cable industry has exhibited a pronounced tendency toward increased vertical integration and concentration of cable system ownership. As a result, the 1992 Cable Act proposed and the Federal Communications Commission implemented restrictions on such activity. Two antitrust concerns include the size of programming discounts offered to large multiple-system operators and price and carriage discrimination by vertically integrated programming networks. The empirical model in this paper attempts to systematically measure the effect of ownership concentration and vertical integration on the programming cost and price of cable operators. We find that concentration and integration lower the programming cost to cable systems affiliated with larger multiple-system operators. These discounts are partially passed along to consumers in the form of lower prices.     

中压电缆配电网中避雷器实证研究

分析了35 kV电缆配电网中变电站进线避雷器的事故案例,研究了35 kV、6 kV中压配电网中几种常见过电压的幅值,并与阀型避雷器和氧化锌避雷器的放电电压相比较,对装设进线和馈线避雷器的实际效果和合理配置提出见解.     

乙丙橡胶绝缘潜油电缆的几个重要性能指标

根据我国JB 5332—91《额定电压3.6/6kV及以下电动潜油泵电缆》和CB/T16750—1997《潜油电泵机组》中有关潜油电缆的技术条件、性能指标的规定,与美国IEEE1018—1997中规定的不同,指出该乙丙绝缘潜油电缆的合理性能指标,并提出建议。     

HBB系列玻璃钢电缆保护管的应用前景

1前言目前及今后几年进行的全国城市电网改造,将需用大量的保护管来保护电缆。从情报资料及国外考察获悉,近几年在美国、日本、西欧等先进国家已普遍推广使用玻璃钢管作为电缆保护管。在国内,目前仅有杭州新世电力复合材料有限公司是生产HBB系列玻璃钢电缆保护管的专业生产厂家,其产品市场前景非常广阔。2优点HBB系列玻璃钢电缆保护管具有强度高、重量轻、不变形、内壁光滑、摩擦系数小、穿缆轻滑、不损伤电缆、绝缘。防腐蚀、不生锈、使用寿命长等优点。特别是无电腐蚀、非磁性,适合于单芯电缆敷设。而钢管是磁性材料,必须经过特…     

聚乙烯电缆绝缘专用树脂的质量优化

通过对35 kV聚乙烯电缆绝缘专用树脂内杂质产生的原因进行分析,针对性地提出了在线控制措施和增设35 kV聚乙烯电缆绝缘专用树脂杂质含量指标,以达到降低杂质含量,进一步优化聚乙烯绝缘料专用树脂质量的目的.