A graduate course on finite element analysis for electromagneticapplications

The author describes a graduate course on finite element analysis for electromagnetic applications that is offered at Marquette University. This course covers the theoretical background that is essential to learning how to model electromagnetic devices. The course stresses the practical aspects of applying the finite element method to engineering and design problems     

A survey of graduate programs in electromagnetic applications

Survey results which summarize the research activities of 64 American colleges and universities in areas that deal with applications of electromagnetic theory are presented. The names and research interests of faculty at each institution are listed along with the numbers of MS and PhD students who are enrolled during March 1989 or graduated in 1988. The EM-related research funding and the average net annual compensation paid to graduate students are also given for the surveyed schools     

A substitution algorithm for solving nonlinear circuits with multi-frequency components

In this paper, we present an efficient algorithm for calculating the steady-state response of nonlinear circuits such as forced circuits driven by multi-frequency-component signals, forced oscillators, and coupled oscillators. We call the technique a substitution method because the variation at each step is calculated by solving an associated time-invariant sensitivity circuit at each frequency component of the residual error, whose circuit is derived from a relaxation method. the algorithm is very simple and efficient, and it can be applied to a wide variety of nonlinear circuits.     

A switching-parameter algorithm for finding multiple solutions of nonlinear resistive circuits

An efficient algorithm for finding multiple solutions of a system of nonlinear algebraic equations is presented. This algorithm consists of solving an associated system of first order nonlinear differential equations whose independent variable may be switched from one variable to another during each integration step. The choice of the forward Euler predictor and Newton-Raphson corrector for integrating the differential equations leads to an extremely efficient method for implementing this switching-parameter algorithm. This approach involves only the recursive solution of an associated system of linear algebraic equations and can be easily programmed. The switching-parameter algorithm can also be used to derive the driving-point or transfer characteristic curve of multivalued resistive nonlinear networks.     

Overview of a course on electronic instrumentation design for senior undergraduate and graduate students

A course on Electronic Instrumentation has recently been developed at the University of Nebraska, which specifically emphasizes design aspects. The objective of the course is to expose senior undergraduate and graduate students to electronic as well as nonelectronic concepts concerned with instrumentation design and development. Topics covered include basic analog and digital circuits, filters and oscillators, linear and switching power supplies, low-noise techniques, signal processing, phase-locked loops (PLLs), transducers, grounding and shielding, thermal analysis, vibration analysis, electronic packaging, wiring and cabling, and engineering ergonomics. The course is intended to enable students to succeed as entry-level engineers in industry.     

非线性电路平衡点全局渐近稳定的充分必要条件

利用向量比较原理,得到了确定非线性电路平衡点全局渐近稳定的充分必要条件。结果表明,非线性非自治电路的唯一稳态的充分必要条件,可以用一个常数矩阵的Hurwitz条件决定。     

Elman神经网络在非线性模拟电路故障诊断中的应用

Elman神经网络把隐层输出反馈回输入层,是一种动态递归神经网络,改进的Elman网络能逼近任意动态非线性系统。本文研究了Elman网络的结构和学习算法,并把改进的Elman网络应用于非线性模拟电路故障诊断激励信号参数优化中,以提高故障正确诊断率。首先用改进的Elman神经网络建立故障电路和无故障电路系统模型,然后用遗传算法搜索电路故障诊断的最佳激励信号参数。     

基于AM激励下谱分解的非线性电路故障特征提取

为解决非线性电路故障特征重叠、交叉造成的故障隔离度低的问题,提出一种基于调幅激励下电路响应谱分解的非线性电路故障特征提取方法．利用慢调幅激励下非线性电路Volterra响应谱的可分离性,通过带通滤波器分解出与Volterra级数对应的响应分量;根据线性电路的频响叠加性原理,分析了Volterra响应分量的故障全息性;再由Volterra响应分量提取非线性电路故障特征。最后,通过仿真实例说明该方法有效性。     

A new approach to overcome the overflow problem in computer-aided analysis of nonlinear resistive circuits

This paper is addressed to the so-called overflow problem commonly encountered in the computer simulation of nonlinear resistive circuits containing rapidly varying nonlinearities—such as exponentials found in the models of diodes and transistors. A novel approach which makes use of the arc-lengths of the nonlinear characteristic curves as the variables of iteration is proposed. It is proved, under rather mild conditions, that the arc-length approach not only overcomes the overflow problem, but also leads to a more rapid rate of convergence. Moreover, it is proved that for most practical diode-transistor circuits, the region of convergence associated with the arc-length approach is larger and the convergence of the Newton-Raphson algorithm is not sensitive to the initial guess. Since it is more difficult to make good initial guesses when the size of the network is large, in so far as choosing the initial guess is concerned, the advantage for using the arc-length approach over the conventional approach increases with the size of the network. Extensive numerical experiments confirm the superior convergence property of this approach even for circuits which violate the sufficient conditions invoked by the rigorous mathematical proofs. Although the approach is applicable to a much wider class of nonlinear networks, particular emphasis is focused on diode-transistor networks in this paper.     

Design of shunt capacitor circuits for power factor compensation inelectrical systems supplying nonlinear loads: a probabilistic approach

An optimization criterion is presented which allows proper calculation of reactive power steps in a power factor compensation installation consisting of capacitors and/or filters. Optimization minimizes power losses on supply transformer and cables. The criterion is based on mean value estimation of load reactive power, which is enabled by sampling measurements performed on the examined electrical plant, as well as by probabilistic processing of data. Even the aspect of harmonic pollution is considered in the optimization process, determining the choice between filters and capacitors     

On a nonlinear multiple-centrality-corrections interior-pointmethod for optimal power flow

Large scale nonlinear optimal power flow (OPF) problems have been efficiently solved by extensions from linear programming to nonlinear programming of the primal-dual logarithmic barrier interior-point method and its predictor-corrector variant. Motivated by the impressive performance of the nonlinear predictor-corrector extension, in this paper we extend from linear programming to nonlinear OPF the efficient multiple centrality corrections (MCC) technique that was developed by Gondzio. The numerical performance of the proposed MCC algorithm is evaluated on a set of power networks ranging in size from 118 buses to 2098 buses. Extensive computational results demonstrate that the MCC technique is fast and robust, and outperforms the successful predictor-corrector technique     

模拟电路可测试性分析模型建立

对机载电子设备做可测试性分析是设计ATS的第一步,只有这样才不会在设计过程中无谓地浪费测试资源.本文通过建立各种不同故障类型模拟电路的可测试性分析模型,论述了利用DES理论建立模拟电路可测试性分析模型的基本方法.对模型分析得到的故障隔离率与实际值相吻合.用DES理论建立的模拟电路可测试性分析模型可以与数字、数模混合电路模型在统一的框架中进行可测试性分析,对电路可测试性分析起到一定的作用.     

On a class of nonlinear networks

Some of the properties of a class of nonlinear networks are discussed. The class of networks under consideration is allowed to have very general branch characteristics including couplings among elements of different kinds and discontinuities in time. Firstly, local existence and uniqueness of solutions to the state equations are discussed. Secondly, several global properties of the class of networks are discussed. Some of the properties of the degree of a function and a differential property of implicit function theorem turn out to be useful.     

逆变器用IGBT吸收电路的仿真研究

IGBT的开关速度很高,关断时一般会产生过电压,实际电路中通常都会在IGBT旁加吸收电路(缓冲电路).针对其中五种吸收电路的特点、适用范围进行了描述和比较,并利用MATLAB软件对IGBT(三菱公司的两种第五代IGBT模块)的吸收电路进行了仿真,并给出了试验波形和优化的吸收电路参数选择.     

SSCSSC: a tool for the teaching of digital circuits

The authors present a computer program to support the teaching of digital circuits. The program is used to describe, synthesize, and simulate combinational and synchronous sequential logic circuits, and to help students in their first contact with automatic synthesis tools. The program runs on both MS-DOS and UNIX machines, and it can be given freely to students for home use to significantly reduce the crowding in laboratories. Care has been taken to provide a friendly interface, so that the user can immediately concentrate on the study of circuits instead of having to learn a new program. The software described by the authors is currently used as a support tool in the course on Digital Circuits for Electronic Engineers at the University of Pisa     

Modeling of circuits and architectures for molecular electronics

The considerable progress of recent years have demonstrated the potential of molecular electronics to first enhance the capabilities of silicon electronics and, possibly, to substitute it when the intrinsic physical limits of scalability will be reached by CMOS technology. Despite such advances, a real alternative will only be possible if novel circuit and architecture concepts will be developed, which are fully suited to molecular devices. The purpose of the present paper is to discuss the theoretical activities carried out at the Institute for Nanoelectronics of the Technische Universität München in the field of molecular devices and circuits, critically assessing such work with respect to what has been proposed in the literature. Two approaches to molecular electronics will be analyzed. On the one side, we will deal with transistors based on organic films, and present circuit solutions based on inverters as basic blocks. On the other side, we will consider single molecule devices and the architectures that might allow system implementations.