10kV环网柜的优化与统一

随着城市配电网的发展 ,对设备的要求不断增高 ,经历了不同时期与不同类型的发展历程 ,其中以1 0kV环网柜为基础的开关站 ,由于经济、简便、高效的优势 ,在城市配网中发挥着越来越大作用。嘉兴市从1 995年在配网主干线中开始应用 1 0kV环网柜 ,至 2 0 0 3年底 ,户内外开闭所总数超过 1 1 0座 ,本文根据近 1 0年的应用经验 ,结合实际 ,就环网柜 (开闭所 )的优化与发展提出一些建议 ,供同行参考。     

无槽洛仑兹力无轴承电动机原理和研究现状

介绍了一种新型无轴承电动机--无槽洛仑兹力无轴承电动机.与传统无轴承电动机不同,无槽洛仑兹力无轴承电动机转矩和悬浮力都是由洛仑兹力产生,其优点是无需考虑与永磁体厚度相关的转矩和悬浮力之间的制约关系.文章概述了无槽洛仑兹力无轴承电动机的特点,阐述了无槽洛仑兹力无轴承电动机基本结构、绕组形式、悬浮力和转矩的产生原理,综述了无槽洛仑兹力无轴承电动机研究状况和应用前景.     

Evaluation of the Lorentz law by using a Barlow wheel

In this work, an evaluation of the Lorentz law has been carried out by a Barlow wheel. Basically, a Barlow wheel is a primitive dynamo-electric machine (invented by P. Barlow in 1828) which consists of a metallic cogwheel, which moves around a horizontal axis. The theoretical analysis includes the Lorentz law and the Petroff law, which characterizes the friction between the axis and the bearing. In the stationary state (when the angular velocity is constant), a simple formula can be obtained which relates the current intensity and the angular velocity. Experimental data approximately confirms this formula, and this device can be used as a simple and classical laboratory experiment in basic electromagnetism courses. Some modern complements were used for the acquisition of data, as a light barrier connected to a counter, a voltammeter and a direct-current power supply Therefore, the Barlow wheel, originally designed for qualitative demonstrations, can be used as a quantitative and useful assembly in a laboratory of General Physics     

A Z-transform model of transformers for the study ofelectromagnetic transients in power systems

A Z-transform model, which combines transformer frequency-dependent short-circuit impedances with gain functions, has been developed. It sets up a relationship between transient voltages and currents on both sides of a transformer winding pair. The model can be used to calculate impulse responses of the transformers with open-circuit secondary winding as well as those connected to other networks. It could be incorporated into EMT (electromagnetic transient) programs for calculating the EMTs in power systems in which the distributed characteristics of transformer windings are to be considered     

计算机集成制造系统的理论与实施

介绍了CIMS的概念、基本构成、特点、实施、效益及存在的不足与改进方法。阐述了实施发展CIMS的重要意义。     

Impact of the Coulomb interaction on nano-scale silicon device characteristics

Monte Carlo simulations coupled self-consistently with the three-dimensional Poisson equation are carried out under the double-gate MOSFET structures. The Coulomb force experienced by an electron inside the device is directly evaluated by performing the Monte Carlo simulations with or without the full Coulomb interaction and the Coulomb force on the channel electron corresponding to plasmon excitations is clarified. It is pointed out that the consistency of the boundary condition is achieved only if the long-range Coulomb interaction is properly taken into account, and this is crucial for predicting reliable device characteristics in ultra-small devices. The drain current and transconductance are greatly reduced if the self-consistent potential fluctuations are taken into account.     

电磁阀的控制原理与图符解析

侧重分析电磁阀的主要特点、控制原理,并从应用的角度对工业领域,特别是火力发电厂气动控制系统成熟技术的典型设计作了综述,分别在电磁阀的电磁线圈、各种电磁阀阀体结构、动作过程及电磁阀的分类等方面重．点探讨。     

电磁场对高速运动电荷的作用力-洛伦兹力公式的新形式

百年以前,由洛伦兹建立的电磁场对电荷的作用力公式－－洛伦和公式,是在低速情况下得到的,后来被推广到了任意运动速度,本文根据一般电磁场理论信了运动电荷的电磁场特性,认为该公式只适用于低速情况,对高速运动电荷不再适用。并在此基础上导出了适用于任意速度的新的洛伦兹力公式,它在低速情况下转化为通常的洛伦兹力公式。     

精密压力表示值误差测量不确定度的评定及其Excel计算方法

通过对精密压力表示值误差测量不确定度的分析、评定与实例计算,详细介绍了如何在Word文档中插入Excel电子表格;如何利用Excel的计算功能来实现实验标准差与合并样本标准差的计算。各不确定度分量的汇总,合成标准不确定度及其有效自由度和扩展不确定度的计算;如何利用设计好的Excel电子表格来实现对任意一个测量结果的扩展不确定度的计算。     

Convergence theory for multi‐input discrete‐time iterative learning control with Coulomb friction,continuous outputs,and input bounds

In this paper we consider the problem of discrete‐time iterative learning control (ILC) for position trajectory tracking of multiple‐input, multiple‐output systems with Coulomb friction, bounds on the inputs, and equal static and sliding coefficients of friction. We present an ILC controller and a proof of convergence to zero tracking error, provided the associated learning gain matrices are scalar‐scaled with a sufficiently small positive scalar. We also show that non‐diagonal learning gain matrices satisfying the same prescribed conditions do not lead to the same convergence property. To the best of our knowledge, for problems with Coulomb friction, this paper represents a first convergence theory for the discrete‐time ILC problem with multiple‐bounded‐inputs and multiple‐outputs; previous work presented theory only for the single‐input, single‐output problem. Copyright © 2004 John Wiley & Sons, Ltd.     

Numerical modelling of the stationary Maxwell–Lorentz system in technical devices

The particle-in-cell method is coupled with boundary-fitted co-ordinates in order to model the stationary Maxwell–Lorentz problem in technical devices. New numerical algorithms describing the transition between the grid model and the mesh-free model are developed and the existing techniques of finite difference schemes for equidistant grids are extended to non-equidistant, arbitrarily shaped, convex four-point meshes. The modelling process is described, and both the numerical approximation and the algorithms are discussed. Applications in different technical devices show the flexibility of the method.     

A structural-functional approach to unification of autonomous power-supply systems in the process of their modernization

A modern approach to unification of structural elements and systems of autonomous power supply in general in the process of their modernization, which is due to an increase in consumer demand for power supply, is considered. The main attention in solving these problems is paid to a structural and hierarchical functional approach to unification of automated systems of autonomous power-supply systems and comparative analysis of obtained results.     

卷积交织技术原理及其FPGA实现

交织技术在数字通信中得到了广泛的应用,纠错码与交织技术结合起来能够显著提高数字通信质量。本文介绍了卷积交织与解交织的原理与主要性质,在此基础上采用VerilogHDL设计了一种面向RS（255,223）码的卷积交织器。该方案利用随机存储器（RAM）来代替先进先出移位寄存器（FIFO）的功能,采用基地址和偏移地址的方式来控制读写操作,实现数据延迟,完成卷积交织的功能。该设计具有实现简单,占用资源少的优点。     

一种新的变压器磁路到电路的转换模型及多种方法的统一

变压器的建模计算方法有两个关键点,一个是磁化曲线的表示,一个是磁路到电路的等值转换模型。针对第二个关键点提出了一种新的转换模型,把铁芯柱、铁轭、漏磁路径都等效成匝数为一次绕组的线圈,利用电流拆解方法表示各线圈的电流关系,利用磁通的连续性表示电动势的关系,从而得到与磁路等值的电路模型。该电路模型与对偶原理法得到的电路模型相同,并且该模型可以得到与统一磁路UMEC法相同的变压器铁芯动态自感和互感值,验证了所提新方法的正确性以及所提方法、对偶原理法、统一磁路UMEC三种方法的统一。最后给出计及变压器饱和特性的电磁仿真计算流程图。     

发展中的测量不确定度理论

讨论实际测量系统模型的分类以及相应的不确定度表述，并给出计算不确定度的采样方法。文中还介绍测量兼容性、数据融合方法、动态测量系统不确定度评价和测量过程控制等与测量不确定度理论相关问题的研究进展。     

The Kalman filter in the context of adaptive filter theory

Model‐based adaptive algorithms are usually derived with the help of the Wiener‐Hopf equation based on empirical statistics. They are often interpreted as an extension to their model‐independent counterparts, i.e. the stochastic‐gradient based adaptive filters. As a consequence, it is generally not considered worthwhile to show the analogy between Kalman filters and adaptive filters. This article pursues just these two goals. First, it tries to remove the notion that the Kalman filter is a complicated and unnecessary detour from the subject of adaptive filtering. Second, the advantage of a deeper insight into adaptive algorithms from Kalman's viewpoint emerges from our treatment. Based on a time‐varying FIR filter model, the Kalman filter is completely derived and serves as a general framework for the special case of model‐based adaptive filters. Copyright © 2004 John Wiley & Sons, Ltd.     

The connection function–theory and application

An approach to circuit theory is presented wherein the connections are modelled as a system valued function of a system valued variable. It is shown that for a large class of circuits and systems that this nonlinear function can be viably represented by four matrices through which it may be readily manipulated, both theoretically and computationally. The elementary properties of the connection function are derived and the approach is illustrated through a number of applications. In particular, an explicit formula for the sensitivity of a circuit in terms of the sensitivity of its components is obtained; and a semi-analytic solution to a class of CAD problems is formulated.     

电容器储能型轨道电磁炮的理论分析与动态仿真

为分析电容器储能型轨道电磁炮发射过程中的影响因素,介绍了轨道电磁炮的基本原理,建立了电容储能型轨道电磁炮的电路模型,根据此电路模型和电路、电磁场及电动力学原理建立了用于描述轨道电磁炮中电磁过程的微积分方程。同时,建立了用于分析轨道电磁炮的动态仿真模型。仿真结果表明,被发射体的速度随驱动电容容量的增加而增加,随被发射体的质量增加而下降。     

基于博弈论的电力项目管理方法创新与实践

在介绍国内外项目管理的主要模式和分析了我国项目管理的现状及存在问题与不足的基础上,结合多年工作实践经验,根据博弈论,对电力工程项目管理模式进行了创新和实践。     

项目管理办公室(PMO)在研发制造企业的运用研究

本文主要通过对当前项目管理办公室(PMO)的发展趋势,结合项目管理理论知识,通过理论和企业实例,研究实施PMO理念在研发制造行业的可行性,为制造企业如何选择和运用PMO管理方法提供必要依据。