控制策略对机载雷达永磁电机峰值转矩影响分析

针对机载雷达用永磁电机对功率密度的苛刻要求与短时高过载和长时低负载转矩的工况特点,在分析表贴式永磁电机和内嵌式一字形、V字形永磁电机的气隙磁密特点基础上,对比研究了直轴电流为零控制策略和最大转矩电流比控制策略对电机输出峰值转矩的影响。研究结果表明,采用直轴电流为零控制策略,表贴式永磁电机具有更大的峰值转矩;采用最大转矩电流比控制策略,内嵌式V字形永磁电机具有更大的峰值转矩;三种类型电机,相同机载雷达应用工况下,内嵌式V字形永磁电机温升最低。     

Optical and electronic properties of some semiconductors from energy gaps

II-VI and III-V tetrahedral semiconductors have significant potential for novel optoelectronic applications. In the present work, some of the optical and electronic properties of these groups of semiconductors have been studied using a recently proposed empirical relationship for refractive index from energy gap. The calculated values of these properties are also compared with those calculated from some well known relationships. From an analysis of the calculated electronic polarisability of these tetrahedral binary semiconductors from different formulations, we have proposed an empirical relation for its calculation. The predicted values of electronic polarisability of these semiconductors agree fairly well with the known values over a wide range of energy gap. The proposed empirical relation has also been used to calculate the electronic polarisability of some ternary compounds.     

信息系统等级保护测评实践

该文针对社会发展对信息化的依赖程度越来越高,而保障重要信息系统安全也是维护国家安全、保障社会稳定的重要组成部分这一事实.随着重要信息系统等级保护工作的深入,信息系统等级自测评与差距分析得到了广泛重视.文章系统阐述了自测评实践中的基本流程、测评方法与测评成果.     

半导体照明中结温的电学法测试与优化

基于电学法测试半导体照明的结温,实现了结温测试的电路,采用脉冲调制对LED的瞬态结温值进行测试.实脸发现,结温与正向电压的标定系数K值是影响结温测试精度的主要因素,分析了产生误差的主要原因,并对该系数进行修正.测试结果表明:结温的实测值与参考值有良好的一致性,存在误差的原因是采样的延时时间较长,可提高数据采样率和剔除不...     

全固态裸露式Ag／AgCl参比电极的研制及应用

该文报道了一种树脂接界全固态裸露式Ag／Agcl参比电极,勿需电镀氯化,制备工艺简单,性能稳定,是对电解型Ag／AgCl参比电极的一大改进。可代替饱和甘汞电极作为通用型参比电极,同时可减少汞对环境所造成的二次污染,在温度大于75℃时仍能保持良好性能,突破了甘汞电极的局限。     

Fault containment in weakly stabilizing systems

Research on fine tuning stabilization properties has received attention for more than a decade. This paper presents probabilistic algorithms for fault containment. We demonstrate two exercises in fault containment in a weakly stabilizing system, which expedite recovery from single failures, and confine the effect of any single fault to the constant-distance neighborhood of the faulty process. The most significant aspect of the algorithms is that the fault gap, defined as the smallest interval after which the system is ready to handle the next single fault with the same efficiency, is independent of the network size. We argue that a small fault gap increases the availability of the fault-free system.     

嵌入豁口磁芯的13.56MHzRFID读写器天线

本文针对天线线圈产生的磁场强度分布不均匀的现象,提出一种增强天线局部磁场强度的方案.首先,本文从理论出发解释了高频磁场的趋肤效应;其次,基于高频磁场的趋肤效应,提出往线圈中央添加开了豁口的金属磁芯,用以增强磁芯边缘和豁口位置的磁场强度;最后,通过三维电磁仿真软件AnsoftHFSS和MATLAB软件研究不同张角的豁口磁芯对环形天线的磁场强度的影响,旨在找出最优豁口的设计方案,对实际设计的13.56MHz RFID读写器天线具有一定的参考价值.     

球隙火花开关的高压触发装置设计

研制了一种用于高压球隙开关的触发装置,该装置采用了全桥逆变与倍压整流为核心的电路方案.在阐述电路工作原理的基础上分析了输出电压与倍压电容之间的关系,作为参数选择的依据.并设计了以小铜球为触发开关的点火控制回路,保证球隙开关击穿的可靠性与快速性.同时以Atmega16型单片机作为控制核心编写软件程序,保证高压球隙开关工作在电压低抖动的可靠状态.通过PSCAD仿真软件进行了方案验证,并搭建实验样机.实验结果表明,该装置输出电压精度高、充电时间短、性能稳定.