解析国际电磁兼容标准-ISO7637-3

主要介绍了ISO 7637-3道路车辆除电源线外的导线通过容性和感性耦合的电瞬态发射测试方法与步骤,以评价车载电子电气设备对耦合到非电源电路的电瞬态的抗扰度。并详细阐述了电容耦合(CCC)、直接电容耦合(DCC)和电感耦合(ICC)三种方法的瞬态试验脉冲的应用。     

具有雷击浪涌保护功能的路由器设计

针对传统路由器无法有效预防雷击浪涌的缺点,通过在电源和网口端增加TVS防护管、控制PCB地层的安全间距和通过变压器阻隔泄放等手段,在路由器的输入端形成雷击浪涌抑制电路,对电源线和网线上因二次雷击感应产生的浪涌电压脉冲进行有效抑制,防止电子设备过压、过流损坏。产品基于PN结的雪崩效应及爬电距离增大来快速泄放路由器板引入的瞬态高压。     

航天服浪涌抑制电路设计和应用研究

为解决航天服电源带载切换瞬间浪涌抑制功能失效问题,提出一种改进的浪涌电流抑制方法,增加MOS管栅极电压快速泄放通道,设计相对独立的充电电路和放电电路,通过分析计算确定各阻容元件的参数值;仿真计算结果表明,MOS管栅极电压泄放时间由48.55ms减小为554.5μs,充满电时间由90ms变为42ms,放电时间加快,而充电时间相对稳定;经实验测试,电源初始加电及电源切换加电瞬间,浪涌电流峰值均不大于3A,两种工况下浪涌电流都能得以抑制;改进后的浪涌抑制电路有效地解决了带载切换过程中浪涌电流过大的问题,能够很好地应用于航天服的供电系统中。     

磁环在并联型两级压敏电阻中的应用

针对瞬态传导骚扰抑制装置中退耦元件性能衰减、多级浪涌保护器配合失效的问题,搭建了以磁环作为退耦元件的并联型两级压敏电阻群脉冲试验电路。通过对比试验,研究了磁环作为退耦元件的可行性。试验结果表明,磁环作为退耦元件引入两级压敏电阻之间,可有效降低被保护负载两端耦合的骚扰电压峰值,并提高前、后级压敏电阻在导通动作时的瞬态电流分流比。同时,提出了磁环作为退耦元件应用在并联型两级压敏电阻之间时,两级压敏电阻电气参数和退耦磁环绕线匝数的选取方法。该研究可为电气设备浪涌防护领域的相关设计提供参考。     

发动机ECU电源系统的电磁兼容设计

汽车电子化、智能化程度不断提高,汽车电磁兼容已成为重要研究课题。发动机ECU电源系统的抗干扰设计对发动机正常稳定工作起着重要作用。本文通过对汽车内部微机控制点火系统、供电系统以及电磁阀、继电器开关等主要干扰源产生的电磁干扰进行了分析,并从辐射干扰和耦合干扰两个方面,依据国家标准GB/T 21437.2-2008的电源线瞬态抗扰度要求,对ECU内主微控制器QADC部分和电源管理芯片L9741的电源系统进行了抗干扰设计,最后进行了电源线抗扰度测试实验研究。     

一种新型无人机机载电源浪涌保护器的设计

为减小瞬态电压、浪涌电压等对无人机机载DC-DC电源和电子设备造成的危害,针对当前机载电源系统的特点,提出了一种直流浪涌保护器的设计思路和实现方法。首先分析了机载电源浪涌的成因和解决方法,对浪涌保护器的类型和特性进行简单介绍;然后详细说明了新型无人机机载电源浪涌保护器的工作原理和具体实施方案;最后对系统整体进行了电路优化和实际验证,结果证明其浪涌抑制性能良好,性能指标完全能够达到应用要求。     

LittelfuSe推出新型SD和SD-C系列瞬态抑制二极管

<正>2014年6月10日,全球电路保护领域的领先企业Littelfuse公司宣布推出其瞬态抑制二极管阵列(SPA二极管)的最新成员——SD和SD-C系列450W分散式单向和双向瞬态抑制二极管。此类快熔型瞬态抑制二极管设计用于保护破坏性静电放电(ESD)和雷击引致的浪涌电流,是替代低速和直流应用中多层压敏电阻(MLV)的理想选择,因为其可在±30 kV的条件下安全吸收反复性ESD震击而不会对性能造成不利影响,并可安全地耗散高达30A的浪涌电     

-48V电信线卡热插拔方案

1概 述当电路板插入带电背板时,电路板上电源模块或开关电源输入端的旁路电容会在它们放电时吸入很大的浪涌电流。不受控制的浪涌电流将在系统电源上造成瞬态故障,损坏线路板上的器件,这就需要在设计中引入热插拔保护电路。在系统中添加热插拔电路后,可以降低对主电源的要求,从     

矿用产品LonWorks总线接口保护技术

针对矿用产品LonWorks总线接口在实际应用中容易损坏的问题,分析了导致损毁的主要原因是收发信号不隔离、浪涌脉冲和长距离传输等因素,给出了3种由陶瓷气体放电管、自恢复保险丝、瞬态抑制二极管、静电放电保护器件组成的LonWorks总线接口保护电路。测试结果表明,该3种保护电路均满足有关标准的浪涌抗扰度测试要求,应用效果良好。     

基于阻容降压的稳压电路设计

为了解决给智能家用电器所用到的ASIC芯片提供稳定电源电压的问题,设计出阻容降压的稳压电路,该电路对市电进行阻容降压、半波整流、滤波,在稳压电路引入深度电压负反馈使输出电压稳定,该电路具有抗电网干扰和防浪涌功能;经过瞬态分析后,输出电压最终稳定在5.085 9 V,与实际电路测试结果5.04 V仅相差0.045 9 V,该稳压电路已成功应用于电子产品中。     

Only connect: teaching, technology and telesis

Abstract This paper describes an approach to the design of interactive multimedia materials being developed in a European Community project. The developmental process is seen as a dialogue between technologists and teachers. This dialogue is often problematic because of the differences in training, experience and culture between them. Conditions needed for fruitful dialogue are described and the generic model for learning design used in the project is explained.     

European Community policy and the market

Abstract This paper starts with some reflections on the policy considerations and priorities which are shaping European Commission (EC) research programmes. Then it attempts to position the current projects which seek to capitalise on information and communications technologies for learning in relation to these priorities and the apparent realities of the marketplace. It concludes that while there are grounds to be optimistic about the contribution EC programmes can make to the efficiency and standard of education and training, they are still too technology driven.     

一种自适应子融合集成多分类器方法

融合集成方法已经广泛应用在模式识别领域,然而一些基分类器实时性能稳定性较差,导致多分类器融合性能差,针对上述问题本文提出了一种新的基于多分类器的子融合集成分类器系统。该方法考虑在度量层融合层次之上通过对各类基多分类器进行动态选择,票数最多的类别作为融合系统中对特征向量识别的类别,构成一种新的自适应子融合集成分类器方法。实验表明,该方法比传统的分类器以及分类融合方法识别准确率明显更高,具有更好的鲁棒性。     

Avoiding semantic and temporal gaps in developing software intensive systems

Development of software intensive systems (systems) in practice involves a series of self-contained phases for the lifecycle of a system. Semantic and temporal gaps, which occur among phases and among developer disciplines within and across phases, hinder the ongoing development of a system because of the interdependencies among phases and among disciplines. Such gaps are magnified among systems that are developed at different times by different development teams, which may limit reuse of artifacts of systems development and interoperability among the systems. This article discusses such gaps and a systems development process for avoiding them.     

Designing economic np control charts: A programmed simulation approach

This paper presents control charts models and the necessary simulation software for the location of economic values of the control parameters. The simulation program is written in FORTRAN, requires only 10K of main storage, and can run on most mini and micro computers. Two models are presented - one describes the process when it is operating at full capacity and the other when the process is operating under capacity. The models allow the product quality to deteriorate to a further level before an existing out-of-control state is detected, and they can also be used in situations where no prior knowledge exists of the out-of-control causes and the resulting proportion defectives.     

The development of robot art

Going through a few examples of robot artists who are recognized worldwide, we try to analyze the deepest meaning of what is called “robot art” and the related art field definition. We also try to highlight its well-marked borders, such as kinetic sculptures, kinetic art, cyber art, and cyberpunk. A brief excursion into the importance of the context, the message, and its semiotics is also provided, case by case, together with a few hints on the history of this discipline in the light of an artistic perspective. Therefore, the aim of this article is to try to summarize the main characteristics that might classify robot art as a unique and innovative discipline, and to track down some of the principles by which a robotic artifact can or cannot be considered an art piece in terms of social, cultural, and strictly artistic interest. This work was presented in part at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January 31–February 2, 2008     

Explanation and prediction: an architecture for default and abductive reasoning

Although there are many arguments that logic is an appropriate tool for artificial intelligence, there has been a perceived problem with the monotonicity of classical logic. This paper elaborates on the idea that reasoning should be viewed as theory formation where logic tells us the consequences of our assumptions. The two activities of predicting what is expected to be true and explaining observations are considered in a simple theory formation framework. Properties of each activity are discussed, along with a number of proposals as to what should be predicted or accepted as reasonable explanations. An architecture is proposed to combine explanation and prediction into one coherent framework. Algorithms used to implement the system as well as examples from a running implementation are given.     

Three Process Perspectives: Organizations, Teams, and People

This paper provides the author's personal views and perspectives on software process improvement. Starting with his first work on technology assessment in IBM over 20 years ago, Watts Humphrey describes the process improvement work he has been directly involved in. This includes the development of the early process assessment methods, the original design of the CMM, and the introduction of the Personal Software Process (PSP)^SM and Team Software Process (TSP){^SM}. In addition to describing the original motivation for this work, the author also reviews many of the problems he and his associates encountered and why they solved them the way they did. He also comments on the outstanding issues and likely directions for future work. Finally, this work has built on the experiences and contributions of many people. Mr. Humphrey only describes work that he was personally involved in and he names many of the key contributors. However, so many people have been involved in this work that a full list of the important participants would be impractical.     

基于复小波噪声方差显著修正的SAR图像去噪

提出了一种基于复小波域统计建模与噪声方差估计显著性修正相结合的合成孔径雷达(Synthetic Aperture Radar,SAR)图像斑点噪声滤波方法。该方法首先通过对数变换将乘性噪声模型转化为加性噪声模型,然后对变换后的图像进行双树复小波变换(Dualtree Complex Wavelet Transform,DCWT),并对复数小波系数的统计分布进行建模。在此先验分布的基础上,通过运用贝叶斯估计方法从含噪系数中恢复原始系数,达到滤除噪声的目的。实验结果表明该方法在去除噪声的同时保留了图像的细节信息,取得了很好的降噪效果。     

How do children do mathematics with LOGO?

Abstract  This paper considers some results of a study designed to investigate the kinds of mathematical activity undertaken by children (aged between 8 and 11) as they learned to program in LOGO. A model of learning modes is proposed, which attempts to describe the ways in which children used and acquired understanding of the programming/mathematical concepts involved. The remainder of the paper is concerned with discussing the validity and limitations of the model, and its implications for further research and curriculum development.