柔度矩阵在动平衡试验中的应用

在旋转机械中由于偏心质量引起的强迫振动,是比较常见的现象,严重威胁到设备的正常使用。在动平衡试验中,由单盘转子、双盘子、三盘转子和四盘转子上加偏心块,由此采集挠度信号,与理论计算中由柔度矩阵公式推出的结果对比,偏差率低于5%,其实用性得到验证。     

倾斜柱塞泵运动参数的简便计算

本文推导了倾斜柱塞泵运行参数ρ随科盘倾角Φ变化的函数关系式,用此函数关系进行倾斜柱塞系的设计计算,比用传统的函数ρ=f（α）要简单,且比较精确。     

基于Hamilton原理的双跨转子系统建模和转子动态特性分析

研究目的：研究双盘双跨转子/轴承/汽封系统在非线性油膜力和非线性汽封力共同作用下的动力学特性,分析了转子转速、密封力、油膜力和联轴器刚度等因素对转子稳定性的影响。创新要点：采用Hamilton原理和有限元方法建立双盘双跨转子/轴承/汽封系统模型,使得双跨多节点的转子系统数值求解更加容易。研究分析转子转速、非线性密封力、非线性油膜力和联轴器刚度等因素对转子稳定性的影响,为大型转子系统的设计提供理论基础。研究方法：采用Hamilton原理和有限元方法建立双盘双跨转子/轴承/汽封系统模型（图1和2）。应用四阶Runge-Kutta法进行数值求解,并采用轴承处、圆盘处的分岔图、时程图、庞加莱映射图、频率图和相轨迹图等来分析转子系统的动态特性。重要结论：1.通过数值计算分析,转子的转速、非线性汽封力、非线性油膜力和联轴器的刚度对双跨转子的稳定性有重要的影响作用。2.随着转速的上升,双跨转子系统从最初的稳定运动,到三倍周期运动,到准周期运动和多倍周期运动交替出现,运动特性相比单跨转子系统要更为复杂。     

浅议学习“三相异步电动机定子绕组磁动势”的方法

阐述了学习"三相异步电动机定子绕组磁动势"的方法:从单相绕组的磁动势入手,掌握其波形、数学表达式,进而用数学推导和图解法得出三相绕组磁动势。     

Analysis on Dynamic Performance for Active Magnetic Bearing—Rotor System

In the application of active magnetic bearings(AMB),one of the key problems to be solved is the safety and stabiltiy in the sense of rotor dynamics,The project related to the present paper deals with the method for analyzing bearing rotor systems with high rotation speed and specially supported by active magnetic bearings,and studies its rotor dynamics performance,including calculation of the natural frequencies with their distribution characteristics,and the critical speeds of the system.one of the targets of this project is to formulate a theory and method valid for the analysis of the dynamic performance of the active magntic bearing-rotor systemby combining the traditional theory and method of rotor dynamics with the analytical theory and design method based on modern control theory of the AMB system.     

10kV油浸电力变压器高压带分接和垫条排线研究

基于开发10kV油浸电力变压器CAD优化集成系统进行变压器设计时,电磁计算是设计的重要组成部分,其中变压器线匝排列时面临高压带分接和垫条情况,分接段要求分别排线和选线规,且分接段和加垫条区的幅向尺寸要小于正常区的幅向尺寸,结果表明了该方法的有效性。     

转子动平衡技术的研究现状和进展

振动是旋转机械主要的一种故障形式,而振动产生的原因通常来源于转子不平衡,因此在上个世纪中叶转子动平衡技术就应运而生。简单介绍了刚性和挠性动平衡理论,并着重介绍了现场转子动平衡技术和在线动平衡技术,最后对近年来该技术的发展提出了新的问题。     

基于高压场效应管的可调纳秒脉冲源设计

针对诸如变压器绕组形变的脉冲测试法等宽带测试需求,设计了一台由计算机控制并显示脉冲信号源工作参数、基于场效应管的可调纳秒脉冲信号源。实验测试表明,在50Ω负载上脉冲源能产生高斯上升沿20ns、指数下降沿40～200ns分档可调、重复频率0～5kHz连续可调、幅值0～1kV连续可调、体积为32×30×7cm3的纳秒脉冲电源,可满足变压器绕组形变的宽带测试需求。     

三相异步电子电动机定子绕组首尾端的判断

介绍了利用三相异步电动机结构原理判别定子绕组首尾端的两种方法。     

Unpacking Rouché’s Theorem

Abstract

Rouché’s Theorem is a standard topic in undergraduate complex analysis. It is usually covered near the end of the course with applications relating to pure mathematics only (e.g., using it to produce an alternate proof of the Fundamental Theorem of Algebra). The winding number provides a geometric interpretation relating to the conclusion of Rouché’s Theorem, but most undergraduate texts give no geometric insights that lead to an understanding of why Rouché’s Theorem holds. In addition, most texts do not inform students that a stronger version of the theorem exists. In this paper we present a simplified proof of the stronger version, which is a suitable topic for students to pursue as a short project, and provide a geometric argument for the weaker version. Finally, as a project for advanced students, we unpack a standard application of this theorem as used in control systems: the Nyquist stability criterion.