有线电视分配系统设计中的算法

本文介绍了一种在有线电视分配系统设计过程中的简单算法。并通过一个实际例子说明该算法的优势。     

用保角变换法计算单芯偏心电缆单位长度的自感

文章利用分式线性变换计算单芯偏心电缆单位长度的自感,并对结果进行讨论。     

Modelling of URM Walls Retrofitted with Cable：A Comparison Between a Basic Mechanical Model and Distinct Element Method

The Australian love of ＂heritage＂ buildings （most of them are unreinforced masonry （URM） ） means that greater attention is required to secure their performance under seismic or impact loading in the future. A research project has been carried out to develop a new, economic and high strength retrofitting technique for masonry structures. A series of experimental testing on URM walls retrofitted with an innovative technique by cable system have been conducted. In this paper, an analytical model which is based on distinct element method（DEM） is developed to simulate the behaviour of retrofitted walls, in DEM, a solid is represented as an assembly of discrete blocks. Joints are modelled as interface between distinct bodies. It is a dynamic process and specially designed to model the behaviour of discontinuities. In order to assist the practising engineers to design this new retrofitted wall system, a simple mechanical model was also developed to predict the strength of the retrofitted walls. The results obtained from this simple mechanical model are compared with those from both experiments and distinct element model.     

剖析双绞线标准

本文从双绞线的工作原理出发，介绍了基于RJ-45的直通线和交叉线的制作标准及其与各种设备的连接方法。剖析双绞线标准，以利于掌握规律，并正确使用标准，以保证网络的正常运行，最终推进网络技术的发展。     

基于数值信息法的煤巷支护综合设计研究

针对山西大同某煤矿辅助巷道支护结构的锚杆与锚索的设计,采用理论设计、数值模拟、观测设计、工程类比几种方法的综合设计进行方案选择、设计优化。此方案不仅在经济方面,而且在技术、安全方面都满足要求,对类似的工程起到借鉴的作用。     

美国有线电视规制走势探究

美国有线电视产业发展过程中,其规制政策出现了相应的变化.其实,美国有线电视规制的变化过程是紧随着有线电视产业矛盾的变化而相应变化的,有线电视与无线广播电视、消费者、电信产业之间的三对矛盾是促进规制发展的动力源泉.新时期,媒介融合、OTT视频业务对有线电视的发展产生了强烈的影响,引导着有线电视未来的规制重心.     

注浆锚索技术在吕家坨矿的应用

本文结合吕家坨矿三采区5383集中轨道巷注浆锚索应用实践,论述了锚注加固技术的原理、注浆材料、注浆有关技术参数以及注浆施工工艺,通过注浆前后对围岩物理力学特性的观测,检验了锚注加固效果,探讨了注浆锚索在吕家坨矿应用的可行性。     

OPGW光缆断股的分析及处理

通过一起OPGW光缆外层绞线断股现象,分析了其形成的机理和产生的原因,得出了外层采用铝合金单丝时在雷击情况下易产生外层断股的结论,并从设计、施工、运行等方面提出了具体的防范措施。     

论光缆线路障碍点的准确定位

首先说明了光缆线路障碍点精确定位的必要性和重要性,然后提出了影响光缆线路障碍点准确定位的主要因素,在此基础上最后论述了提高光缆线路故障定位准确性的方法.     

Application of time-temperature superposition method in thermal aging life prediction of shipboard cables

The life of shipboard cables will decrease due to the complex aging processes. In terms of the safety perspective, remaining life prediction of the cable is essential to maintain a reliable operation. In this paper, firstly, based on Arrhenius equation, residual life of new styrene-butadiene cable is calculated; result indicates that the degradation rate which changes with time is proportional to thermal temperature. Then second order dynamic model is adopted into the residual life prediction, combined with the time-temperature superposition method （TTSP）, and a new residual life model is proposed. According to the accelerated thermal aging experiment data and Arrhenius equation, TTSP method demonstrates to be an efficient way for life prediction, and life at normal temperature can be estimated by this model. In order to monitor the state of styrene-butadiene cable more accurately, an improved residual life model based on equivalent environment temperature of cable is proposed, and life of cable under real operation is analyzed. Result indicates that this model is credible and reliable, and it provides an important theoretical base for residual life of cables.