William D. Coolidge and ductile tungsten

This paper presents achievements and contributions of William D. Coolidge in the field of electrotechnology. Coolidge discovered a new method of producing ductile tungsten by a combination of reducing impurities and carefully controlled mechanical working. He also became known for his contribution to the development of improved X-ray tube and vacuum tube electronics. During the first world war, he helped developed portable X-ray apparatus for use by military and also worked on project for the sound detection of enemy submarines.     

Target I.D. using natural resonances

The use of electromagnetic natural resonance as non-cooperative target recognition (NCTR) parameters is quite different from the conventional Doppler-based radar approach and is investigated for use in future radar systems. Natural resonance frequencies contained in a target's radar signature are determined by its structure and serve to identify the target. The physics of natural resonances are described, and natural resonance estimation is detailed. Real world implementation of natural resonance NCTR is discussed     

直流电动机的励磁保护

本文分析了直流电动机常用的励磁保护方法,并对励磁保护提出了有效的改进措施,在实用中收到了良好的效果.     

交直交风力发电系统建模与仿真研究

对交直交风力发电系统的工作原理以及控制技术进行了较为全面的阐述,重点介绍了交直交变频器的工作原理;建立相关的数学模型,并在不同输入下进行了动态仿真,对仿真结果进行了分析,验证其控制理论的正确性.     

On the solvability and computation of D.C. transistor networks

A study of non-linear d.c. networks containing transistors, diodes, linear resistors, independent voltage and current sources and linear controlled voltage and current sources, described by Tf(x) + Gx = b is presented. A few theorems concerning both the solvability and numerical computation of d.c. transistor networks are proved. The conditions sufficient for the existence of at least one solution and of a unique solution are defined. A method for numerical computation of the networks without the need to determine inverse matrices is presented and the convergence of the iterative technique is analysed. Suggestions are formulated regarding applicability of the method for computation of an approximate solution (close to the exact solution) which may subsequently be quickly corrected using the Newton-Raphson method.     

D.C. leakage currents in ferroelectric memories

Abstract

Experimental data on d.c. leakage currents in lead zirconate titanate thin films (210 nm) are presented. The data show a flat, ohmic response up to a thresh-hold of approximately 2.0 V, above which they satisfy a modified Childl's Law, with a perfectly quadratic dependence: I = aV². This suggests that at 5 V operation the film behaves as a fully depleted device. The difficulty in distinguishing between Frenkel-Poole, Schottky emission, and true space-charge limited currents is briefly discussed.     

Putting transferable Ph.D. skills to work

The doctoral education process has typically brought about many misconceptions regarding the practicality of the Ph.D. degree. The Ph.D., by definition, requires mastery of a specific subject and expansion of the existing body of knowledge. Many professionals believe this small scope of research and contribution is far less practical for the upcoming engineer as compared to four equivalent years in practice. It is believed that Ph.D. graduates are only suitable candidates for academia and research. However, beyond the narrow-scoped dissertation, the doctoral education teaches desirable practical skills for the practicing engineer that are not emphasized in either the tightly packed undergraduate program or the hectic under-staffed corporate world.     

JG型高电压大电流直流固体继电器设计

给出了JG-（51F-56F）型高电压大电流直流固体继电器的主要技术指标,介绍了该类产品的设计方法,重点介绍了驱动电路的设计和输出电路的设计,并给出了一些重要参数的计算方法。通过检测数据与技术指标的对比,证明设计合理,符合设计要求。     

一种小型直流电磁铁的结构设计

从电磁铁结构形式的选择、磁极形状的选择、铁心的设计、线圈的设计、控制部分的设计等方面介绍了一种小型直流电磁铁的结构设计方法,提出了一种电磁铁设计新思路。     

直流接触器磁系统分析软件开发与应用

在分析方法上实现了有限元法与数值计算的完好接合 ,在技术上完整的封装了ANSYS软件 ,使得磁系统的温度、吸力特性分析都可以通过程序的接口模块 ,调用后台ANSYS批处理程序进行分析。前台参数的改变直接影响后台的分析计算。本软件已初步用于实际设计中。     

移相式软开关逆变型直流高压发生器

介绍了一种新型的直流高压发生器,其主电路逆变桥使用功率ＩＧＢＴ器件,采用最新软开关变逆技术。整机以８０３１单片机为控制核心。     

轧钢电机环火及其原因探讨

环火是直流电机换向恶化的极限状态,其原因及发展过程极为复杂。本文结合轧钢电机环火典型实例,分析环火的主要成因及发展过程,并对防止环火措施进行了讨论。     

直流无刷电机DSP控制器的开发及其在变频电冰箱中的应用

１概述 直流无刷电机（ＢＬＤＣ）因具有显著的节能、低噪声和优良的调速性能等优点,特别适用于电冰箱、空调器等家用电器。传统的ＢＬＤＣ需用转子位置检测器控制器给定绕组供电的逆变器换相,这对降低家用电器的成本、缩小装置的体积、提高运行可靠性都是不利的,需要研制无位置传感器的ＢＬＤＣ控制系统,但因其控制算法的复杂性,监控软件的编写难度及硬件成本偏高等实际问题,限制了其发展。目前国内虽推出若干种ＢＬＤＣ的变频电冰箱等产品,但其中核心的控制器及压缩机则多依赖进口,这增加了相应产品的成本。 现在国外一些公司相继…     

高压断路器中直流电磁铁设计的讨论

本文讨论主压断路器中直流电磁铁的设计问题。提出了这类电磁铁的主要参数是输出的机械功,并得到影响静态机械功、动态机械功和工作效率的一些因素。     

高压断路器中直流电磁铁设计的讨论

本文讨论高压断路器中直流电磁铁的设计问题。提出这类电磁铁的主要参数是输出的机械功,并得到影响静态机械功、动态机械功和工作效率的一些因素。     

李政道猜想和P.C.T守恒定律

本文根据李政道猜想与粒子对产生和湮灭的真空理论,对非轻子衰变的宇称不守恒进行了分析,证明了宇称P和CP的破坏均来源于真空.如将真空也计算在内,则P.C.T守恒定律就都能普遍成立.