Lung ventilation functional monitoring based on electrical impedance tomography

Medically,electrical impedance tomography(EIT)is a relatively inexpensive,safe,non-invasive and portable technique compared with computerized tomography(CT)and magnetic resonance imaging(MRI).In this paper,EIT_TJU_Ⅱ system is developed including both the data collection system and image reconstruction algorithm.The testing approach of the system performance,including spatial resolution and sensitivity,is described through brine tank experiments.The images of the thorax physical model verify that the system can reconstruct the interior resistivity distribution.Finally,the lung ventilation functional monitoring in vivo is realized by EIT,and the visualized images indicate that the configuration and performance of EIT_TJU_Ⅱ system are feasible and EIT is a promising technique in clinical monitoring application.     

高压电机变频改造应注意的问题

本文主要从变频器与电机的联系角度进行分析,以作者多年的工程实践总结探讨了高压变频器在水厂工程施工改造中应注意的问题.     

基于UCC28019的高功率因数开关电源设计与实现

针对传统开关电源对电网产生较大污染以及功率因数低的问题,介绍了功率因数校正（PFC）的基本原理,详细分析了UCC28019的内部结构及特点．利用UCC28019设计出一种高功率因数、高效率、低谐波、低噪声的单相整流PFC开关电源,并对其进行了测试．测试结果表明功率因数大于0．95,效率达到92％,输入电流波形谐波失真小于5％．     

Feedback maximization of reliability of MDOF quasi integrable-Hamiltonian systems under combined harmonic and white noise excitations

We studied the feedback maximization of reliability of multi-degree-of-freedom （MDOF） quasi integrable-Hamiltonian systems under combined harmonic and white noise excitations. First, the partially averaged Ito equations are derived by using the stochastic averaging method for quasi integrable-Hamiltonian systems under combined harmonic and white noise excitations. Then, the dynamical programming equation and its boundary and final time conditions for the control problems of maximizing the reliability is established from the partially averaged equations by using the dynamical programming principle. The nonlinear stochastic optimal control for maximizing the reliability is determined from the dynamical programming equation and control constrains. The reliability function of optimally controlled systems is obtained by solving the final dynamical programming equation. Finally, the application of the proposed procedure and effectiveness of the control strategy are illustrated by using an example.     

电子设备故障电流和谐波电流区分的方案设计

针对如何快速、有效地区分电力系统故障运行状态和不正常运行状态,尤其是短路故障和谐波状态的问题,应用序分量理论,设计了一种可区分故障和谐波的方案,通过仿真测算法,及增加继电保护装置逻辑判断环节中的控制信号,实现了不正常运行状态和故障状态的区别,进而达到继电保护装置正确、可靠地动作的目的。     

ⅡR型和FIR型希尔伯特数字滤波器在无功功率测量中的对比研究

希尔伯特变换在数字信号处理理论和应用中有着十分重要的作用,它维系着对离散序列进行傅里叶变换后的实部和虚部之间或者幅度和相位之间的关系。无功功率测量在电力系统分析中占有非常重要的作用,现代电力系统对无功功率的测量有着更高的要求。本文设计了分别设计了ⅡR型和FIR型希尔伯特滤波器,对比分析了各自在测量无功功率的优缺点。以便于应用在不同精度要求的测量仪表中。     

简论谐波的危害和治理

非线性负载的广泛应用,使得电压和电流的波形产生畸变,在电力系统中产生了大量的谐波。谐波的危害影响到用户使用的安全性和供电质量,电网谐波污染的治理越来越受到关注。     

静止无功补偿装置在轧机供电系统中的应用

介绍静止无功补偿装置（SVC）在轧机供电系统中的应用,说明此装置在抑制谐波、电压波动等电网冲击中所起的作用。     

基于LabVIEW的谐波实时在线监测系统的设计

基于LabVIEW的谐波实时在线监测系统的设计的基本思想是运用虚拟仪器技术取代传统的谐波监测分析仪,使系统功能更加多样化和灵活化。该系统的核心部件是数据采集电路,通过USB接口把采集到的信号发送给PC机,由PC端基于LabVIEW软件编程实时在线显示各次谐波电压电流波形和各参数值。该系统可以在任何需要进行谐波分析的领域使用,使谐波分析的工作更加快捷和方便。实验结果表明该系统具有分析效果好、检测方便,易于功能扩展等优点。     

配电网的动态无功补偿与谐波抑制

针对电能质量由于谐波污染日趋下降的现状,阐述了几种抑制谐波的技术措施,重点研究了动态无功补偿与消波技术的应用,指出无功补偿与谐波治理同时进行,才能提高系统的电能质量。关键词