贯流式水轮发电机集电环短路原因分析及改善措施

白石窑水电厂1～4号发电机组在投运初期,集电环曾多次出现绝缘降低甚至短路的非正常现象。通过分析,引发故障的原因主要是碳刷架、集电环绝缘结构设计欠妥、运行环境恶劣以及机组的振动过大。针对上述原因,改进了绝缘结构设计上的不足,加强巡视和维护检查,装设工业电视监控,加装碳粉回收装置,对受油器进行防漏油或喷油技术处理,加强清污力度、提高发电水头以便减少机组振动,从内外因加以防范和改善后,问题得到了标本兼治,取得了理想的效果。     

基于计算机声卡的虚拟仪器的设计

主要介绍通过计算机的声卡来实现对虚拟仪器的设计，模拟了示波器、信号发生器和频率计等设备的基本功能，详细介绍了系统的硬件设计方法及软件流程。该系统主要适用于音频范围的各种信号的采集与产生。     

SF6气体绝缘电容式电压互感器研制

本文介绍西容公司新研制的一种完全无油化的SF6气体绝缘电容式电压互感器,提出了关键技术问题解决方案和产品绝缘结构的设计思路.并介绍了研制成功的110kV和220kV系列产品的结构、技术参数、性能指标、试验考核情况和产品特点.     

液氨储罐保冷改造效果评定

作者结合实例，论述了氨罐保冷改造的设计、选材及施工，给出了改造后两年的测试结果，并对测试结果进行了分析。     

Ideal-gas thermodynamic properties for natural-gas applications

Calculating caloric properties from a thermal equation of state requires information such as isobaric heat capacities in the ideal-gas state as a function of temperature. In this work, values for the parameters of thec _p ⁰ correlation proposed by Aly and Lee were newly determined for 21 pure gases which are compounds of natural gas mixtures. The values of the parameters were adjusted to selectedc _p ⁰ data calculated from spectroscopic data for temperatures ranging from 10 to 1000 K. The data sources used are discussed and compared with literature data deduced from theoretic models and caloric measurements. The parameters presented will be applied in a current GERG project for evaluating equations of state (e.g., the AGA 8 equation) for their suitability for calculating caloric properties.     

地面数字声音广播（DAB）及其覆盖规划的考虑

简要描述了近几年来研究开发的为移动、便携和固定接收服务的地面发射数字声音广播(DAB)系统总的特点、应达到的技术和运行要求。重点介绍了系统采用的最适合克服移动接收中出现的多径效应影响的先进源编码技术(MUSICAM)、信道编码技术(COFDM)等的基本原理、系统参数、并介绍了规划DAB业务时,在VHF/FM频段考虑的最佳频段及频谱利用改善情况,还提供了DAB单频网洛(SFN)覆盖的大体情况。其内容取材均来自1990～1992年EBU、CCIR等的最新文稿资料。     

Improvement of the methods of reproducing and transferring the dimensions of the unit of sound pressure in an aqueous medium under free-field conditions

Methods of reducing the predominant components of uncertainty in standards of sound pressure in an aqueous medium in a free field, and also methods of increasing the accuracy when the dimensions of the unit of a physical quantity are transferred by the means employed in natural measurements are reviewed. __________ Translated from Izmeritel’naya Tekhnika, No. 8, pp. 59–63, August, 2007.     

迎接挑战加速调整不断增强冶金矿山生存与发展的能力

回顾和总结了通钢矿业公司把市场经济的挑战作为创新发展的动力和机遇，加速自适应性调整，使矿山经济步入持续、稳定、健康发展的良性轨道。     

Degradation of polyethylene terephthalate films in the presence of lubricants for HFC 134a: a critical issue for hermetic motor insulation systems

Earlier studies conducted in the use of sealed tubes with polyalkylene glycol lubricants and polyethylene terephthalete (PET) films revealed that the PET films exhibited embrittlement and (visual) degradation. This led to an investigation of PET embrittlement mechanisms with the new lubricants used with HFC 134a. The lubricants studied were three polypropylene glycols (the monol, the diol and the completely end-capped glycols), pentaerythritol ester and a blend of monol and ester. The effects of moisture content, temperature and lubricant structure were studied. All lubricants in this study were of viscosity grade ISO-32 (150 SUS). The results were compared to PET film embrittlement in the presence of CFC 12 and mineral oil. This study reconfirmed the earlier findings that the PET films must be dried to lower than 0.1 wt.% moisture content for use in hermetic systems. This paper discusses the effect of the moisture content of the lubricant and the effect of the lubricant structure on PET films. The dependence of the various mechanisms on temperature is shown. Esters and end-capped polyalkylene glycols are recommended for use with HFC 134a.     

微机控制材料试验机的开扰源分析及抗干扰措施

分析和探讨了微机控制材料试验机所受干扰的来源和通道，并采用屏蔽和隔离等一系列措施抑制各种干扰,以达到提高微机控制试验机系统试验结果的可靠性和精确度。