《华东电网500 kV变压器全过程管理技术规范>的实施要点

介绍了在执行《华东电网 5 0 0 k V变压器全过程管理技术规范》过程中 ,应强调管理是从基建到生产 ,从选型、安装到运行维护的全过程管理 ,重点介绍了变压器在订货过程中应高度重视诸如对于选用非强油循环的冷却方式、三相共体变压器、抗短路能力以及过励磁问题 ,也对变压器安装过程中水分控制、运行中气相色谱分析和局部放电试验要求作了简述     

Assessment of factors considered to be important in handling tasks by expert handlers

Twenty-eight experienced handlers, considered the best in two transport companies, were interviewed using a questionnaire consisting of partially closed-ended questions. They had to assess 20 videotape handling sequences showing two different handling methods to determine, for 10 factors and overall, which one was the best. They were asked about the inportance of these factors in their choices of the best method. The aims of the study were to verify whether there was a consensus among experienced handlers as to what was a good handling method and to identify the factors taken into consideration by them. Results show the lack of consensus on the best methods. Handlers favor different strategies depending on the worjk context and their own priorities.     

精密有源互感器的研制

本文介绍了精密有源电流互感器的原理和设计方法。该互感器的准确度达到０．０１级，线性度优于１×１０－５．     

粉煤灰少熟料水泥的研究

采用复合外加剂充分激发粉煤灰潜在活性，配制出早期强度较高的３２５＃少熟料水泥。本文介绍该水泥的配制原理与方法，分析了代替普通水泥配制建筑砂浆的可行性。     

变压器绝缘电阻低于允许值的处理

本文就一台主变压器绝缘电阻低于“规程”允许值的问题，进行了原因分析，提出了简易的处理方法，取得了较好效果，同时提出了几个值得探讨的问题，对提高变压器的安全运行水平有一定的现实意义。     

基于非接触监测的隧洞反演分析可行性探讨

本文根据全站仪非接触测量原理，分析了隧洞测点位移量测的三维误差计算式。随后对全站仪位移量测的误差精度进行了分析，得到了满足反演计算要求的量测误差判别式，并提出全站仪位移量测的可行性判别方法。最后通过算例给出了判定实际工程反演分析可行的设站及仪器的优选方式。分析结果认为目前全站仪的测量精度还只适用于洞室断面较大、总位移量较大的情况，对洞室反演计算的普遍适用还有一定距离。     

高坝流激振动响应的反分析方法

为分析高速水流诱发高坝泄流结构的振动问题，根据结构动力学、随机振动理论和最优方法的基本理论，提出了基于谱分析及遗传算法的振源反分析方法，采用本文方法，可以由少量测点的动位移实测值反馈分析出各激振源等效荷载谱，通过流激振动响应的正分析方法得到整个结构在水流动力荷载作用下的动力响应，对水工结构的流激振动进行正确全面的评估，为结构损伤动态监测和诊断提供新的技术手段。并通过拉西瓦拱坝泄洪水弹性模型试验实测值与反分析计算值的比较验证了本文方法的合理性。     

Series resonant ZCS‐PFM DC‐DC power converter with high‐frequency high‐voltage transformer link for high‐power magnetron drive

This paper presents a single lossless inductive snubber‐assisted ZCS‐PFM series resonant DC‐DC power converter with a high‐frequency high‐voltage transformer link for industrial‐use high‐power magnetron drive. The current flowing through the active power switches rises gradually at a turned‐on transient state with the aid of a single lossless snubber inductor, and ZCS turn‐on commutation based on overlapping current can be achieved via the wide range pulse frequency modulation control scheme. The high‐frequency high‐voltage transformer primary side resonant current always becomes continuous operation mode, by electromagnetic loose coupling design of the high‐frequency high‐voltage transformer and the magnetizing inductance of the high‐frequency high‐voltage transformer. As a result, this high‐voltage power converter circuit for the magnetron can achieve a complete zero current soft switching under the condition of broad width gate voltage signals. Furthermore, this high‐voltage DC‐DC power converter circuit can regulate the output power from zero to full over audible frequency range via the two resonant frequency circuit design. Its operating performances are evaluated and discussed on the basis of the power loss analysis simulation and the experimental results from a practical point of view. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 153(3): 79–87, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20126     

Heat evolution of high-volume fly ash concrete

In this paper, the results of a laboratory investigation conducted with heat evolution of high-volume fly ash (HVFA) concrete are presented. Heat evolution of concrete was studied by measuring the temperature increase in concrete under adiabatic curing condition. Characteristic of heat evolution of fly ash concrete was found to be strongly dependent on the replacement level of fly ash and dosage of superplasticizer used to maintain workability. It was also found that using fly ash as cement replacement resulted in a reduction on the maximum temperature rise. Increasing the replacement level of fly ash caused lower temperature rise in concrete. Superplasticizer caused a delay in peak temperature rise time; this is taken as an indicator that high-dosage superplasticizer used in concrete caused retardation in hydration of cement. Concretes having similar ingredients showed similar peak temperature rise whether they are superplasticized or not.     

Influence of cage design on precision of tube-trap bioassay for attractants of the onion fly,Delia antiqua

Responses of onion flies,Delia antiqua, to known attractants were measured in the laboratory with a novel tube-trap bioassay. The relative numbers of flies caught in tube traps baited with enzymatic yeast hydrolysate, brewer's yeast, andn-dipropyl disulfide were similar to those obtained previously with cone traps in the field. Changing the shape of the bioassay cage from a cuboid to a cylinder decreased the experimental error obtained from analysis of variance, as did rotating the floor of the circular cage. This bioassay should be useful in evaluating attractants for other insects that orient along the substrate.Diptera: Anthomyiidae.Paper No. 11327 of the Michigan State University Agricultural Experiment Station. Received for publication June 8, 1984.