电磁干扰在数字电路板设计中的研究

主要从电磁兼容设计的目的、电磁干扰的途径以及电磁干扰抑制等方面进行阐述，为实际电路板设计提供参考．     

电磁干扰抑制技术

介绍了电磁干扰(EMI)的基本概念,围绕电磁干扰三要素,介绍了各种不同的电磁干扰抑制技术以及电磁兼容设计思路,强调了电子产品在设计初即进行EMC研究的重要性。     

电磁兼容技术在自动化专业实验室中的应用

电磁兼容作为一门边缘学科,其应用越来越广泛;分析了自动化专业实验室中主要电磁干扰,并结合电磁干扰产生原因的具体情况,探讨了采取相应抑制措施。     

高压油泵车电磁兼容性综合解决措施

本文从电磁兼容的三要素,即电磁干扰传播途径、电磁敏感设备及电磁干扰源三方面入手,论述了高压油泵车电磁兼容性的综合解决措施。     

基于电磁兼容的智能建筑综合布线系统

综合布线系统在智能建筑中发挥着神经系统的作用 ,布线系统所受到的电磁干扰严重影响着数据传输的质量。本文应用电磁兼容理论 ,从干扰源、传输途径和系统抗干扰能力三方面出发 ,采取屏蔽、滤波、接地等措施 ,对智能建筑综合布线系统的电磁兼容性设计要点进行了归纳和总结     

光伏逆变器内部电磁干扰抑制电路研究

在光伏逆变系统中,内部电磁干扰是影响其工作稳定性和可靠性的重要因素,能否有效地控制内部电磁干扰决定着系统的成败.文章以一款3 kW离网光伏逆变器设计为例,分析了系统内部主要电磁干扰的分布,并提出了具体解决方案.     

B777飞机APU滑油量指示空白故障解析

20世纪以来由于大型民用航空器的飞行和操纵系统安装了先进的电子/电气技术设备,随着机载设备内部的CPU和数据传输总线频率的不断提升,为维修领域带来与此相关的电磁兼容及电磁干扰等方面的问题;电磁干扰是一种突变电磁信号或辐射磁场,它散布于飞机的所有角落;由于电磁干扰的存在,对飞机电子/电气系统造成不同程度的系统故障或者系统功能变化故障.本文主要对B777-200飞机APU滑油油量指示空白故障的排故方法进行分析.     

开关电源的EMC问题分析

电磁兼容,简称(EMC),是指装置或系统具有在其设置的预定场所投入运行时,既不受周围电磁环境的影响,又不影响周围环境,也不发生性能恶化和误动作,而能按设计要求正常工作的能力。抑制电磁干扰,防止相互之间的有害影响,成为电控设备和自动化系统可靠运行的关键技术之一。     

开关变换器传导性电磁干扰的抑制浅析

大功率变换器设计过程中的开关变换器不仅要求电子和安全需要,而且要满足电磁兼容规范.在本篇文章中,讨论的重点是传导性电磁干扰的问题,在降低EMI方面采用两个不同DC/DC交换器的拓扑结构作了简单比较:高端开关和半桥同步整流器.简要提出一些设备中EMI来源的寄生效应和拓扑结构.对开关变换器中的电磁干扰的抑制措施进行了简要分析.     

计算机电磁干扰性综述

一、计算机电磁兼容的重要性电磁兼容是指电器、电子产品在规定的电磁环境中能正常工作 ,并不对该环境中任何设备产生不能承受的电磁干扰。这包含着两方面的意思 :首先产品要在电磁环境中能正常工作 ,对于电磁环境中的电磁干扰有一定的抵御能力 ,不会影响设备的正常工作。其次 ,产品本身在工作中对环境产生的电磁干扰不应超过一定量值 ,不对该环境中的其他设备产生过度的不能承受的干扰。计算机是一个含有多种电子元件的电子系统 ,内部元器件之间、各传送通道之间以及外部设备对内部设备之间的电磁干扰 ,严重地威胁着计算机工作的稳定性、可…     

电磁屏蔽中的一般概念及技术方法

电子设备已被广泛应用于生产生活各个方面。由于设备的小型化、集成化程度越来越高,设备之间的相互电磁干扰(EMI)也成为一个重要的问题。为此,国际组织提出了一系列技术规章,要求电子产品符合严格的磁化系数和发射准则。符合这些规章的产品称为具有电磁兼容性EMC(Electromagnetic Compatibility)。     

English-medium instruction in law and the humanities in higher education: the role of teacher identity

ABSTRACT

Recent research on English-medium instruction (EMI) has examined university instructors’ professional identities in science and social science rather than in the humanities. To fill the gap, this qualitative case study explores the ways in which 13 university instructors in law and the humanities in Taiwan perceived their identity and exercised their agency as teachers. The findings indicated that these instructors had three ideal teacher identities, including educators in global and local contexts, subject matter instructors, and EMI instructors. Each determined teachers’ choice, design, and enactment of EMI practices, as well as their notions of language use and objectives. This study highlights the primacy of preferred teacher identities in the manifestation of teacher agency, identifies enabling and constraining effects of teacher agency, and emphasizes the significant roles of discipline-specific communities and ethnicity and nationality in EMI practices. As such, teacher identities should be taken into consideration in professional development to empower instructors to take actions that maintain their commitments to EMI.     

Learner Resistance to English-medium instruction practices: a qualitative case study

The internationalization of higher education has resulted in the growth of English-medium instruction (EMI) practices and research. The existing EMI research has documented learners’ favorable attitudes toward EMI but not necessarily its practices. Learners’ dissatisfaction has not been viewed as a form of resistance. Through the notion of learner resistance that underscores agency in defiance, this study examined the occurrences of learner resistance and the reasons for it by investigating Chinese learners’ experiences in an undergraduate business English-taught program in Taiwan. Multiple sources of data, including interviews, stories, and class observations, were gathered for analysis. The findings showed that most Chinese learners resisted an unhelpful curriculum, pedagogy, and context. Their resistance may be related not simply to academic disciplines but more importantly to a Confucian Heritage Culture of learning. Such findings highlight learner agency in resisting actions and call for further investigation into potential learner resistance in EMI practices.     

评估风险的期望损失计算及应用研究

Expected shortfall(ES) is a new method to measure market risk. In this paper, an example was presented to illustrate that the ES is coherent but value-at-risk(VaR) is not coherent. Three formulas for calculating the ES based on historical simulation method,normal method and GARCH method were derived. Further, a numerical experiment on optimizing portfolio using ES was provided.     

Calculation of Expected Shortfall for Measuring Risk and Its Applications

Expected shortfall(ES) is a new method to measure market risk. In this paper, an example was presented to illustrate that the ES is coherent but value-at-risk(VaR) is not coherent. Three formulas for calculating the ES based on historical simulation method, normal method and GARCH method were derived. Further, a numerical experiment on optimizing portfolio using ES was provided.     

北斗车载导航系统的电磁兼容试验与实践

针对北斗导航系统在车载终端的应用现状,根据车辆车载电子设备在车内外电磁干扰源及电磁兼容检测的必要性,阐述了北斗导航车载终端的试验标准及测试过程,提出北斗导航车载终端的试验项目、目的、标准、要求、结果等,对北斗导航终端测试标准和规范的制定及产品的推广有较好的示范作用.     

基于进化策略的消防应急救援决策

近年来,随着社会的发展,城市中各种突发事件的发生频率越来越高,因此需要加强对城市应急决策支持系统(Emergency Decision Supports System,EDSS)的研究。进化策略是受自然进化过程启发,并成为求解全局优化问题的重要方法。将进化策略应用于EDSS中的消防救援事件的推理决策过程,提高了EDSS处理复杂问题的决策能力,实验证实了此方法的有效性。     

对CAD技术发展前景的探讨

本文概述了CAD(Computer Aided Design)技术的基本概念及其应用领域的发展状况,认为CAD技术存在缺陷和不足的主要原因是由于缺乏知识表示和推理机制。本文通过阐述专家系统技术的定义、组成及其领域,预示了CAD技术今后的发展方向和趋势。我们分析了我国专家系统技术和CAD技术目前的应用状况,指出在CAD技术中采用专家系统技术不仅是必要的而且是可能的,目的是为了引起人们对专家系统技术的足够重视。     

数字系统中的电磁兼容探讨

分析了对数字系统性能影响严重的噪声源--串扰噪声、反射、接地公共阻抗噪声等,提出了抑 制电磁干扰的有效措施.