Fault detection for continuous‐time switched systems under asynchronous switching

In this paper, the problem of fault detection for continuous‐time switched systems under asynchronous switching is investigated. The designed fault detection filter is assumed to be asynchronous with the original systems. Attention is focused on designing a fault detection filter such that the estimation error between the residual and the fault is minimized in the sense of H _∞ norm. By employing piecewise Lyapunov function and average dwell time techniques, a sufficient condition for the existence of such a filter is exploited in terms of certain linear matrix inequalities. Finally, an example of a switched electrical circuit is provided to illustrate the effectiveness of the proposed approach. Copyright © 2013 John Wiley & Sons, Ltd.     

开关电源新技术的应用研究

以功率MOSFET和IGBT为代表的、集高频、高压和大电流于一身的功率半导体复合器件,表明传统电力电子技术已经进入现代电力电子时代,开关电源的工作频率得以大大提高,一些新技术的应用更是进一步提升了开关电源的性能。开关电源拥有更广阔的发展空间和应用前景。     

基于交换机技术的网络安全策略研究

本文对交换机及其作用进行了简单的概述,并对基于交换机技术的网络安全策略进行了详细的分析和探究,以期为保障网络的安全流畅运行提供借鉴意义.     

洛河电厂6kV厂用电源双向快速切换

由于快切装置生产厂家只能提供一种逻辑,无法满足"厂网分开,竞价上网"后降低成本的要求,为此对厂家装置进行改进。针对以上要求,提出增加一套快切装置(称为反切柜)用于备用段自投。用这套快切装置进行两台机组与备用段电源开关之间的切换,通过设定的转换开关进行选择,并增加相应逻辑。这样避免了使用购网电量。同时实现无论哪台机跳闸备用电源均能投入运行。     

一种新型零电压零电流开关移相全桥变换器

为了解决传统零电压零电流开关（ZVZCS）PWMDC/DC变换器滞后桥臂零压范围较小、环流损耗大的问题,采用串联双变压器、滞后桥臂带辅助网络和倍压整流电路,提出了一种新型零电压零电流移相全桥变换器.首先分析了变换器在稳态下的各种工作状态,给出了相关计算公式,并制作了一台实验样机进行原理验证.实验结果表明：该变换器能够在较宽的负载范围内实现滞后桥臂的零电压开通,重载下实现零电流开通,从而极大地降低高频电路初级开关损耗和次级电磁干扰.     

Method of Predicting Water Content in Crude Oil Based on Measuring Range Automatic Switching

Water content in output crude oil is hard to measure precisely because of wide range of dielectric coefficient of crude oil caused by injected dehydrating and demulsifying agents.The method to reduce measurement error of water content in crude oil proposed in this paper is based on switching measuring ranges of on-line water content analyzer automatically.Measuring precision on data collected from oil field and analyzed by in-field operators can be impressively improved by using back propogation (BP) neural...     

Phase field simulation of the 180°domain-switching process in PbTiO_3 single crystal under an antiparallel electric field

The process of 180°domain switching in PbTiO_3 single crystal under an antiparallel electric field was investigated by the three-dimensional phase field simulation,especially the effect of electric field on the type and duration of domain switching.It is found that the polarization reversal of domains takes place under an antiparallel electric field in PbTiO_3 single crystal.The results of the phase field simulation indicate that there is only 90°domain switching under a weak electric field.With the rise...     

一种支持多业务承载的广义光突发汇聚机制

引入广义光突发汇聚(GOBA)概念对传统光突发交换(OBS)进行扩展,形成新的广义OBS(GOBS)网络。针对GOBS的多业务承载目标,提出了一种支持多业务承载的GOBA机制,采用将业务最小时延要求作为汇聚时间的汇聚方式,将多种用户数据业务汇聚到不同粒度的广义数据突发(GDB)中。仿真结果表明,在GOBS环境下,与MSMAP(max burst-size max assembly period)机制相比,GOBA能够在满足较高数据成功接收率的基础上显著地减小约10%的总体数据超时率,同时降低约15%的突发碰撞率,并提高约20%信道利用率。     

自激多谐振荡器的电路仿真与应用

本文着重介绍了自激多谐振荡器的电路仿真过程。首先阐明了对称的自激多谐振荡器的工作原理;其次应用电路仿真软件Multisim10对自激多谐振荡器进行了简捷的仿真分析;最后以脉冲信号发生器为例说明了自激多谐振荡器的应用问题。     

电机控制中混合空间矢量脉冲宽度调制的分析与仿真

直接转矩控制利用选择电压矢量达到磁链和转矩的控制,而参考矢量的变化导致各个矢量的等效作用时间发生变化.传统的直接转矩控制在电机磁链脉动和电流脉动方面存在一定的缺陷.SVPWM电压型逆变器换向序列与定子磁链脉动有一定关系,本研究在混合空间矢量脉宽调制方法的基础上研究了不同换向序列的定子磁链均方根脉动大小,并根据脉动量最小的原则将每个磁链扇区分成5个不同的区域,每个不同区域通过采用不同的换向序列,从而极大的减少了磁链的脉动.通过逆变器仿真和快速傅立叶变换分析了交流电机在改进混合SVPWM下的电流仿真结果,并与常规方法进行比较,验证了上述方法的有效性,为进一步研究直接转矩的性能改善奠定了基础.