新型功率步进电机驱动电源

功率步进电机运行的好坏，在很大程度上取决于其驱动电源，我们对已有的驱动电源所存在的问题进行了分析，并进行了改进，取得了满意的效果。     

小型立式电动机用大推力滚动轴承的使用

根据ＹＬＳＴ３１５－８，１１０ｋＷ３８０ＶＩＰ４４电动机需要承受的６０ｋＮ轴向推力的要求，对轴承承载能力进行了计算，舍弃了滑动轴承结构，选用了大推力滚动轴承，并设计了相应的轴承安装结构。     

单相电容运转电动机的计算机辅助设计

分析了单相电容运转运机的原理,了单相电容运转电动机的计算机辅助设计方法,提出了一种电机设计的综合与优化的思想。     

YCT系列电磁调速电动机存在的问题和改进意见

文章指出了ＹＣＴ系列电磁调速电动机设计中存在的问题，然后通过理论分析和研究，对设计公式作了修改，并进行了全系列复算，最后对全系列电机提出了改进方宁，可供各有关生产厂参考。     

Y2系列三相异步电动机（机座号63～355,IP54）技术任务书

阐述了新系列设计的必要性和设计原则。规定了电动机使用条件，外壳防护等级，结构及安装型式和传动方式，功率等级和范围，功率等级与安装尺寸的对应关系。对新系列的力能指标、堵转转矩、噪声和振动等指标提出了目标水平。对绝缘等级、冲片外径、主要材料、基本系列与派生系列的关系、标准化通用化工作要求、设计计算参数选定的原则、结构设计方案和工艺原则等作了明确论述。为落实上述任务安排了若干试验研究工作项目。对新系列技     

三相异步电动机CAD软件包

对已投入实际使用的三相异步电动机CAD软件包的自动设计原理，实施方案及绘图模块等作了较为详细的介绍，并给出了自动设计实例。     

高压电动机故障原因分析及防止对策

本文根据我厂５０台高压时机的故障统计，从设计制造工艺、振动、过电压、运行和检修维护等方面分析了高压电动机发生故障的原因，并提出了具体的防范措施。     

调压调速实心转子异步电动机性能改进研究

介绍和分析了调压调速实心转子异步电机的结构，特性，调速原理，并结合样机试制，介绍所采取的措施，以及改进效果。     

五相混合式步进电动机四步一个循环的轻重步现象

我国从１９８７年开始生产五相混合式步进电动机以来，就发现在半步方式工作时有四步一个循环的走步不均匀现象。本文给出了较完善的分析和说明，实验校核了分析的正确性，确定表明这种现象是特定的绕组联接和功率驱动方式的产物，也就是说采取不同的功率驱动电路和绕组联接，不仅影响电动机的转矩性能指标，而且对走步的均匀性也有一定的影响。     

步进电动机的闭环控制

讨论了超前角在步进电机闭环控制中的作用，用延时方法调整转换角得了较好的转速特性。     

Closure to discussion of "An efficient technique for the evaluation of lightning-induced voltage in a cylindrical vessel containing charged oil"

For original article by C. Buccella and A. Orlandi see ibid., vol.39, no.2, p.368-73, Mar./Apr. 2003 and for discussion by B. J. C. Burrows see ibid., vol.42, no.2, p.535 Mar./Apr. 2005.     

Closure to discussions of "Electric arcing burn hazards"

For original article and discussions see ibid., vol.42, no.1, p.134-45, Jan./Feb. 2006. The authors respond to discussion comments by C.M. Wellman (p.142), P.S. Hamer (p.143-4) and T.E. Neal (p.145).     

用变汽温法检验300MW机组高中压缸中间轴封改造效果

介绍利用变汽温法测量高中压缸中间轴封漏汽量的原理和方法,并列举了在某电厂300MW汽轮机高中压缸中间轴封改造前后的应用实例。提出可以用此方法测量高中压缸中间轴封改造前后的漏汽量,从而可以量化地检验轴封改造效果。     

Discretization Scheme for the Density-Gradient Equation and Effect of Boundary Conditions

In recent years, the density gradient theory (DG) (M.G. Ancona and H.F. Tiersten 1987, Phys. Rev. B. 35(15): 7959–7965, M.G. Ancona 1990, Phys. Rev. B. 42: 1222) has been established as a viable alternative to the solution of the Schrödinger equation for solving problems such as charge density distribution in MOS inversion layers and MOS tunneling (M.G. Ancona 1998, J. Tech. CAD(11), M.G. Ancona et al. 2000, IEEE Trans. Electron Devices 47: 1449). Primary advantages of the DG method over the Schrödinger method are flexibility in extending to multi-dimension and easiness in incorporating into the conventional drift-diffusion or hydrodynamic solver (C.S. Rafferty et al. 1998, Proc. SISPAD, p. 137, A. Wettstein et al. 2001, IEEE Trans. Elec. Dev. 48: 279). However, the DG term that represents the quantum effects is a singular perturbation term and requires special care for discretization (X. Wang 2001, Master's thesis, University of Massachusetts, Amherst). In this work, we examine the validity of the linear vs. the nonlinear discretization scheme and the effect of boundary conditions on the scheme used.     

面向对象技术及其在电力系统中的应用

详细讨论了面向对象建模技术、面向对象方法学以及面向对象技术的优越性。重点介绍了面向对象技术在潮流计算、电力系统仿真、电力系统安全分析与控制、数据库、人机界面、人工智能、调度员培训仿真中的应用。     

Beiträge zur Elektrodynamik des Elektroschocks

Inhaltsübersicht I. Ziel der Arbeit. —II. Das Grundmodell. —III. Das Grundpotential. —IV. Wirkung kleiner Inhomogenitäten: 1. Analyse des Innenbereiches; 2. Analyse des Außenbereiches. —V. Einfluß der Randschicht auf das Strömungsfeld. —VI. Zusammenfassung.Mit 33 Textabbildungen     

Discussion of `Analysis of a new variable-speed singly salientreluctance motor utilizing only two transistor switches' by L. Xu et al

C. Patak maintains that the motor analyzed by L. Xu et al. in the above-titled paper (see ibid., vol.26, no.2, p.229-36 (1990)) cannot operate as specified by the authors. R.M. Davis, in a separate discussion points out that the above-titled paper is based on earlier work by L. Xu and T.A. Lipo (1987, 1988) that had prompted him to publish a paper in which he reached a completely opposite conclusion, and that L. Xu et al. have neither noted nor referenced his work. In reply, L. Xu et al. point out that Patak has been misled by Fig. 4 of their paper and provide clarification. They also explain why they did not consider Davis's paper and rebut his arguments. They also note that the captions for Figs. 14 and 15 of their paper should be reversed     

High voltage AC resistive current measurements using a computerbased digital watts technique

A computer-based technique is described which can accurately determine high-voltage AC resistive currents by obtaining the watts loss of the test specimen and dividing by the true r.m.s. (t.r.m.s.) value of the applied voltage Therefore, the normal concern for guarding against stray capacitive currents and for the exact repetition of test setup geometry on successive testing are not required for accurate measurements of AC resistive current. The watts loss calculation is based on the general formula for average watts so that the resistive current can be measured accurately with some harmonics of the fundamental present in both the test current and the supply voltage. A digital oscilloscope is used to acquire the test voltage and current so that special-purpose amplifiers are not required. The overall system accuracy is verified to less than ±1.21% of full-scale current. A microprocessor was used to compute the following parameters: average power, t.r.m.s. voltage, t.r.m.s. resistive current, t.r.m.s. capacitive current, total t.r.m.s. current, and the magnitude of calculated measurement error. The waveforms displayed are volt-ampere, voltage, and total current. An EHV aerial lift boom, a 115 kV station post insulator, and a metal-oxide surge arrester are evaluated using this technique to illustrate the measurement advantages     

Historical highlights in cardiac pacing

The benchmarks in cardiac pacing are identified, beginning with F. Steiner (1871), who rhythmically stimulated the chloroform-arrested hearts of 3 horses, 1 donkey, 10 dogs, 14 cats, and 8 rabbits. The chloroform-arrested heart in human subjects was paced by T. Greene in the following year (1872) in the UK. In 1882, H. Ziemssen in Germany applied cardiac pacing to a 42-year old woman who had a large defect in the anterior left chest wall subsequent to resection of an enchondroma. Intentional cardiac pacing did not occur until 1932, when A.A. Hyman in the US demonstrated that cardiac pacing could be clinically practical. Hyman made a batteryless pacemaker for delivery in induction shock stimuli (60-120/min) to the atria. His pacemaker was powered by a hand-wound, spring-driven generator which provided 6 min of pacemaking without rewinding. Closed-chest ventricular pacing was introduced in the US in 1952 by P.M. Zoll et al. Zoll (1956) also introduced closed-chest ventricular defibrillation. W.L. Weirich et al. (1958) demonstrated that direct-heart stimulation in closed-chest patients could be achieved with slender wire electrodes. S. Furman and J.B. Schwedel (1959) developed a monopolar catheter electrode for ventricular pacing in man. In the same year, W. Greatbatch and W.M. Chardack developed the implantable pacemaker.     

Continuing Engineering Education around the World?The Concept of Continuing Education at Siemens AG

As the subject matter is quite extensive only a few problems will be covered in this short presentation. I hope, however, to give you a clear picture of the in-company education and training system that will be described below. By following the instructions of the Chairman I hope I will be able to provide a basis for the ensuing discussion. This presentation is divided into the following subtopics. Section I. Organizational environment. Section II. Corporate view of continuing education. Section III. In-house educational opportunities. Section IV. External educational opportunities. Section V. Final remarks.