三峡工地高压供电线路故障判断方法的探讨

高压供电设备故障特别是输电线路的高压接地故障对工地的影响是相当大的。由于接地故障为隐性故障，没有明显的物理现象，且若是长期接地可能会发展成较为严重的两相或三相短路故障，使系统解列运行直至崩溃；由于工地流动人员较多，还易造成电击事故。利用高压一相接地时在线路中产生零序电压这一特性来迅速判断和切除接地的用电设备，可以保证各项施工的顺利进行。     

真空行业现状及未来国内市场

简单扼要的概述了真空行业的发展历史，以较详细的统计数据阐述了2002年行业经济运行情况，并通过对相关行业“十五”发展规划的研究，对今后5～10年真空设备的市场进行了分析预测。     

Electrical conductivity in iodine-doped ethyl cellulose

The electrical conductivity of solution-grown ethyl cellulose (EC) films, 5–30 μm thick, has been studied in the sandwich configuration (metal–EC–metal) as a function of iodine concentration from 0.5 to 5.0 wt% ratio. The studies were conducted in the temperature range 333–383 K, while the field was varied over the range (3.0–5.5) × 10⁴V/cm. Aluminium was used as the lower electrode, while the upper electrode was of Al, Ag, Cu, Au or Sn. Certain transient effects such as a large burst of current immediately after the application of field were observed. An attempt was made to identify the nature of the current by comparing the observed dependence on electric field, electrode material and temperature with the respective characteristic features of the existing theories of electrical conduction. The results show that the electrical conduction follows Ohm's law at lower fields, while at higher fields, space-charge limited current (SCLC) was observed. It was also found that Richardson–Schottky emission was responsible, to some extent, for the transport of charge carriers in the polymer. The conductivity of the films increased on doping with iodine. The dopant molecules are considered to act as additional trapping centes and provide links between the polymer molecules in the amorphous region, thus resulting in the formation of charge transfer complexes.     

新型光电混合式电流互感器设计

设计了一种光电混合式电流互感器,它由传感头、光纤传输和光电转换器、信号处理电路和工作电源4部分组成。这种结构具有绝缘性能高、可靠性强、质量小等特点,并对误差情况进行了分析。     

关于正整数的k次根的整部

对于给定的自然数m，令口α（m)为m的是的次根的整部。即：α(m)=[m^1/k]。研究了α(m)的渐近性质，并给出了一个有趣的渐近公式。     

基于高速摄像的ESPI全场动态特性测量

采用高速摄像与ESPI技术相结合,将运动中的被测物位移随时间变化的状态以序列图像的形式实时记录,并运用图像处理技术,成功地实现了ESPI动态测量。测量了悬臂梁的自由振动过程,获得了悬臂梁的振动周期、振动频率和阻尼系数等动态特性,实验结果与理论计算值相吻合。     

NETWORK6000在脱离子水处理过程中的应用

脱离子水处理单元是一种顺序控制单元，对时序控制有严格的要求。文中介绍了一种新型的控制系统NETWORK6000在PTA装置脱离子水单元中的应用状况，为中小规模的装置应用提供了一种较典型的思路和借鉴，最后对系统的应用状况进行了评价。     

镀锌钢带工艺技术改造

本介绍了将氰化钠镀锌溶液转换为氯化钾镀锌溶液的镀锌工艺过程，从工艺、健康、环保、成本等方面进行阐述。     

Cis–trans isomerization of olefinic alcohols promoted by Rh(I) complexes

Homogeneous hydrogenation and isomerization reaction of cis-2-butene-1,4-diol has been investigated in ethanol by using tris(triphenylphosphine)chlororhodium(I), RhCl(PPh₃)₃, and triethylamine at 303 K and 0.01–0.1 MPa partial hydrogen pressure. Under reduced H₂ pressure, the geometric isomerization reaction occurs, to a high extent, leading to trans-2-butene-1,4-diol up to 93% selectivity at 90% conversion of the cis analogous. Effects of H₂ partial pressure as well as triethylamine, added phosphine and olefin concentrations on the rate of reaction and on the products distribution were also investigated. The results obtained can be interpreted on the basis of a proposed mechanism in which RhH(PPh₃)₃ is the active species. The high selectivity towards cis-trans isomerization of cis-2-butene-1,4-diol is attributed to steric factors of the Rh(I) coordinated triphenylphosphine groups.     

GPS在水面流速流向测量中的应用

传统的水面流速流向测量多采用经纬仪交会法,此法需要大量的人力和设备,工作量大且费时。近几年,随着全球定位系统(GPS)的广泛应用和实践,在一定范围内,采用GPS定位法替代经纬仪交会法施测水面流速流向。介绍了GPS定位法的测量原理、设备,以及测量方法。通过对GPS定位法的精度和优缺点的分析,得出采用GPS定位法施测水面流速流向具有较高的推广价值。