Recent progress in inverse problems in electrocardiology

The considerable progress achieved in the inverse problem of electrocardiography over the last decade has provided grounds for optimism about the possibility of approaching significant clinically relevant applications in the next decade. However, there are a number of basic questions that still remain. In addressing these questions, the authors feel it is important to seek solutions that emphasize physiological rather than mathematical significance. This approach leads to twin requirements for useful inverse solutions: accuracy, defined in a physiologically meaningful (and not just averaged and mathematical) sense, and reliability, not only to measurement noise but also to geometric modeling errors and other uncertainties that are inescapable in practical application. Studies using analytically tractable models may still be relevant, but it seems more important to find solutions to practical inverse problems, which will move the field toward wider acceptance and credibility     

University Education in Electronics in the United Kingdom

Although the overall aims of university engineering education in the U. S. A. and the U. K. are broadly similar, the means of achieving these aims in the two countries are rather different. This paper discusses teaching methods and philosophies in the Department of Electronics at the University of Southampton and compares them with attitudes in the U. S. A. First, high-school curricula in the U. K. are reviewed, as they determine the quality of students at university entry. Then, the probable future pattern of industry, and the aims of a university education are discu sed. The courses devised to train both "systems" and "device" engineers, including the all-important laboratory training, are outlined together with examination and assessment techniques. Postgraduate activities include a new type of postgraduate Master's degree course in semiconductor product technology and industrial techniques.     

非晶态合金材料应力阻抗效应研究进展

应力阻抗效应(SI)是近年来在非晶态合金材料中发现的又一新的具有研究和应用价值的特殊物理效应,利用这种效应可以研制出高灵敏度的应力/应变传感器。简单介绍了应力阻抗效应的理论依据,分析了近几年来国内外在这方面的研究进展,主要有非晶丝、非晶带和薄膜应力阻抗效应的研究以及不同处理工艺对其应力阻抗效应的影响,适当的处理工艺引入的各向异性对应力阻抗效应的提高有很大的贡献。     

Electroluminescence in insulating polymers in ac electric fields

EL (electroluminescence) in several polymeric materials was investigated in the electric field range <90 kV/mm. We used polymeric films with semi-transparent gold electrodes: low density polyethylene, polypropylene, polytetrafluoroethylene and polyvinylchloride. The EL characteristics were very low EL inception fields (2 to 20 kV/mm) which strongly depend on the material and very low energy photon emission (mainly in the red region of 1.6 to 1.8 eV). These results reveal that EL emission occurs predominantly in the metal-polymer interface region rather than in the bulk of the polymer at the applied field. We present a model of EL emission in the metal-polymer interface region to explain our results qualitatively. In this model, the mechanism of EL emission is the radiative recombination of the electrons and holes trapped at the surface states of the polymer, which causes photon emission in the red region. The EL inception field and EL intensity depend on the density of the surface states of the polymers     

Thermal processes in a streamer discharge in water

The propagation features of a streamer discharge in water have been investigated. Based on the experimental data obtained in the study of water discharges in a nonuniform electric field, due propagation of streamers is explained as the evaporation of water at the tip of the streamer and around it. The energy balance in the process of the streamer propagation is calculated for a sub-microsecond discharge in distilled water. It is shown that the energy released in the pre-breakdown process is sufficient to evaporate the liquid in the streamer channels. Similar velocity of the streamer propagation in both tap and distilled water substantiates negligible effect of ionic current density onto the streamer propagation process. These estimations, based on experiment, have relevance to the discussion of the nature of the dielectric breakdown of water     

美国电力市场中的金融交易模式

介绍了在美国电力市场中,为了规避价格风险而设计的日前市场和实时市场双结算体系,以及双边交易和电力金融期货的交易结算模式,分析了其对电力市场的稳定和电力系统运行的作用,揭示了其规避风险和适应电力系统实际运行的原因,并指出,日前市场、双边交易和电力金融产品等非实时电力交易是为适应电力商品的特殊性而提出的金融交易模式。最后对我国的电力市场交易的发展提出了建议。     

光在大气层中的散射与传输研究

本文根据电磁散射理论来分析光在大气层中的散射，导出散射截面与波长的关系，从而分析大气层对光能传输的影响     

2004年全国电网继电保护装置运行中的问题分析

文章介绍了2004年全国电网继电保护与安全自动装置的运行情况,重点介绍了继电保护(元件保护、线路保护)因装置本体的问题造成的保护不正确动作情况,并对运行中突出的问题,如串补装置保护本身的问题进行了分析,通过相互交流,认真总结了运行中出现的问题,吸取经验教训进一步改进工作,提高整体运行水平。     

Ensuring energy security in Russia in a transitional economy

The relevance of the study lies in the fact that increasing state energy consumption in the modern world leads to an increase in global energy consumption, which changes the international energy trade. The current processes determine the essence of national energy security, since for developing countries, it is important to secure national demand, guarantee export supplies and improve favourable terms of cooperation with producers and consumers. The purpose of the study is to identify and examine the factors that affect energy security of Russia in a transitional economy. In order to implement this measure, the economy and society must provide a favourable political, institutional and economic environment for the development of an innovation climate. There is particular interest in studying energy cooperation and various state projects, which reflect the link between security in general and current specialisation. The practical relevance of the study lies in the increasing importance of studying this field, which contributes to the reorganisation of new methods for global energy security that have turned out to be particularly relevant in research activities in recent years.     

Progress in Japan in electrical insulation at high temperatures

It is expected that the use of electrical equipment at high temperatures will increase in the future, and the demand for heat-resistant insulation that can be used at temperatures above 300°C will increase. In addition, this high temperature electrical equipment will need to be higher in voltage and have a larger capacity. Accordingly, research and development will be needed to study the high temperature behavior of insulating materials, the insulation manufacturing process, and functional evaluation methods of insulation systems. Progress in Japan in R&D of insulation systems at higher temperatures is discussed     

Problems in the Education of Engineers in England

The paper opens with a review of the general background to engineering education in the United Kingdom, commenting on some effects of social ideas on educational institutions and their curricula. A review is made of the recent and present situations in the secondary schools, with special attention being given to the curriculum of those who subsequently continue their studies full-time in universities and colleges. The curricula in these latter institutions is then reviewed and some of the teaching problems are outlined. The paper concludes with some speculation about future trends.     

超高频法在发电机局部放电检测中的应用

设计了一套基于超高频 (UHF)法的发电机定子局放检测系统 ,实验室研究结果表明该方法可检测到发电机定子各类局部放电 ,分析和比较了超高频信号在空气和金属导体中的传播规律。该系统与预先安装在某发电厂0 #机组上的方向传感器和中性点的电流传感器相结合 ,联合在线监测发电机的结果表明UHF法可准确检测到发电机中的局部放电信号 ,且信噪比极高     

旧变电站电缆混放的改造方法介绍

旧变电站经过多年的运行和更动,无论电力电缆或控制电缆都十分凌乱,是旧变电站改造工程的一项十分困难的工作。凌乱的电缆对运行安全威胁极大,必须理顺。这里介绍惠州220kV湖滨变电站电缆改造成功的经验,供同行参考。     

世界铅酸蓄电池的研究动态

概述了第七届亚洲电池会议（7ABC）论文的主要研究内容与结果，并报道了此次会议的概况。     

Unusual cases of gassing in transformers in service

This paper presents some unusual cases of gassing in transformers in service without an actual fault. These cases reveal that hydrogen production caused by stray gassing may be due to strongly hydro-treated oils, but is also very strongly influenced by transformer materials. Stray gassing with overproduction of saturated hydrocarbons with no production of hydrogen and no increased rates of hydrogen, ethylene, and other fault gases has probably always existed and is possibly related to oxidation. The overproportional development of methane and especially ethane proceeds in the first years of service and reaches a plateau after considerable consumption of oxygen. Possibly, this process is also catalytically triggered by transformer materials. Catalytic phenomena and stray gassing can be distinguished from a transformer fault through regular checks not only of the absolute DGA values but also the rates of gas increases.     

风电在我国能源发展中的定位

我国在能源结构调整和积极开发可再生能源等方面取得了显著成绩,尤其是风力发电实现了倍增式发展。但风电的高速发展与电力系统、产业体系和政策机制之间存在诸多不协调,需要理清根本原因,进一步深化解决。基于我国风电发展的既有特点和现实问题,从能源利用、能源发展的角度和风电发展的最终目标3个方面进行逻辑论证,提出了风电的能源定位问题,论述了当前风电发展应立足于风电产业化体系的完善以及智能电网建设和新储能技术研究,为未来风电大规模发展打下坚实基础。     

OPPC光缆在固原地区农网通信中的应用

目前广泛应用的OPGW和ADSS,在电力系统通信中发挥了巨大的作用,但由于其自身特点的限制,并不适合在35kV以下中低压电网中使用,因此OPPC应运而生。文章主要从OPPC技术特点、工程设计、施工、运行维护等方面,对OPPC在固原电网中的应用作了详细的阐述。     

超级电容器组单体电压的动态均衡

本文针对超级电容器在串联中存在的问题,介绍了一种利用先进的高效率双向DC—DC变换技术,将多个双向推挽变换器通过一个多绕组的变压器实现相互耦合,应用多源激励变压器原理的超级电容器组单体电压的动态均衡电路,通过能量的耦合,实现了串联超级电容器组单体电压的实时动态均衡,使超级电容器组延长有效使用寿命,提高了超级电容器的工作可靠性。     

Safety conditions in manholes in the vicinity of substations

In many cases, the manholes for maintaining various installations including power and telecommunication cables, water-, remote heating-, and gas-pipes are located in a close vicinity of power substations. The paper analyzes the risks of the occurrence of dangerous potential differences within the manhole and on the surrounding ground surface during ground faults in the substation. Possible protective measures are discussed.