基于TH102芯片的电源电路

采用TH102芯片设计的超低功耗开关电源，不仅需对输入／输出进行隔离，而且差模干扰和共模干扰要低。反激式开关变压器和反馈控制回路设计，以及考虑电磁兼容性对电路的改进，是其关键技术。反激式开关变压器设计包括计算初级电感量、设计变压器变比、减小变压器漏感、设计反激式变压器工作方式。实践证明，基于TH102芯片的电源电路质量事靠、性能稳定，具有很大的推广价值。     

基于续流型半桥高压电源的设计与仿真

设计半桥高压电源,针对提高稳定性和效率的问题,为提高半桥高压电源的效率和稳定性,克服传统不对称半桥高压电源在效率和稳定性上的不足,提出在高频变压器原边增加由辅助开关管和功率二极管组成支路的续流型半桥高压电源,并通过Saber软件搭建高频变压器和续流型半桥高压电源的电路模型进行仿真.仿真结果显示电源主开关管工作在对称状态,而且能够实现零电压开通,辅助开关管在主开关管关闭期间实现零电流导通,电源效率和稳定性得到提高.与传统的半桥高压电源相比,改进方法减轻了变压器漏感和主开关管结电容之间的振荡,证明了方法的有效性和可行性.     

SPWM全桥逆变器输出变压器直流偏磁的抑制

分析了SPWM开关型变换器中输出变压器产生直流偏磁的机理。提出了一种基于电压电流反馈控制技术抑制正弦波逆变器偏磁的方法,并提供了较为实用的拓扑电路,同时分析了它的工作机理。该电路的有效性在介质阻挡强电离放电用IGBT全桥逆变电源中得到了验证。     

基于UC3842的多输出开关电源设计

本文阐述了一种基于UC3842 PWM控制器的新型多路输出反激式开关电源电路的设计.该设计详细给出了变压器、漏感消除电路、启动电路以及电压电流反馈电路的设计过程.实验结果表明该电源性能优良.作为电机控制的电源模块,具有很高的应用价值.     

ZVZCS全桥PWM DC-DC变换器的小信号建模方法

针对ZVZCS全桥PWMDC-DC变换器的软开关工作,分析了变压器漏感和辅助谐振电路对变换器动态特性的影响。在PWM开关等效模型的基础上,结合变换器谐振电路的工作特点,提出了一种ZVZCS全桥PWMDC-DC变换器小信号分析方法,这种建模方法适用于不同类型的ZVZCS全桥变换器。通过对小信号传函幅频及相频特性的分析,证明了这种小信号分析方法具有物理意义清晰、计算简单等优点。应用这种小信号模型,依据变换器的动态性能指标对ZVZCS全桥PWM变换器中谐振元件的参数进行设计,可以使这种软开关变换器的性能得到进一步的提高。     

ZVZCS全桥PWM DC-DC变换器的小信号建模方法

针对ZVZCS全桥PWM DCDC变换器的软开关工作,分析了变压器漏感和辅助谐振电路对变换器动态特性的影响.在PWM开关等效模型的基础上,结合变换器谐振电路的工作特点,提出了一种ZVZCS全桥PWM DC-DC变换器小信号分析方法,这种建模方法适用于不同类型的ZVZCS全桥变换器.通过对小信号传函幅频及相频特性的分析,证明了这种小信号分析方法具有物理意义清晰、计算简单等优点.应用这种小信号模型,依据变换器的动态性能指标对ZVZCS全桥PWM变换器中谐振元件的参数进行设计,可以使这种软开关变换器的性能得到进一步的提高.     

单端反激式开关电源中变压器的设计

变压器是开关电源中的核心元器件,它的性能好坏对整个开关电源的设计能否成功至关重要.根据设计实例,详细介绍了反激式变压器设计的一般步骤和注意事项.设计的脉冲变压器工作在CCM(连续电流模式)方式下,应用在八路输出的开关电源电路中,工作时性能稳定.     

基于脉波倍增的新型24脉TRU可靠性分析与试验

提出了采用小容量半桥辅助电路与12脉变压器、2组整流桥构成多电飞机24脉变压整流器(TRU)的方法。该方法利用半桥辅助电路向12脉波直流电压母线注入电压纹波,实现脉波倍增,构成结构简单、变压器质量轻、整流桥少的24脉TRU,达到简化变压器结构、降低变压器质量,以及降低整流桥数量的目的。分析了拓扑工作模态,推导了输入输出变量表达式,设计了辅助电路,开展了辅助变压器变比优化设计和样机试验等工作;研究了机载TRU的失效率预计方法,针对55℃环境温度的典型情况,开展了新型TRU和常规24脉TRU的失效率预计比较研究。结果表明,所提出的24脉TRU不但结构简单、质量轻,且具有良好的输入输出性能和较低的失效率。     

一种双环控制多输出电源的设计与应用

本文阐述了一种新型多路输出的单端反激式开关电源电路的设计及应用.该设计以UC3844 PWM控制器为核心,采用了电流反馈和电压反馈双环控制电路.文中详细给出了电压电流反馈电路、漏感消除电路、启动电路以及变压器的设计过程.实验及应用结果表明该电源性能优良,具有稳压效果好,纹波小,负载调整率高等优点.作为电机控制的电源模块,具有很高的应用价值.     

基于HIP4081的移相全桥DC-DC变换器的设计

随着我国通信、电力系统以及个人数字产品的快速发展,模块电源的应用越来越广泛.高可靠小功率DC-DC变换器已成为电子电源的一个重点发展方向.主要介绍了以H桥驱动芯片HIP4081为主控电路的小功率DC-DC变换器设计.为了进一步改善开关电源的中的磁性元件性能、减小磁件体积,分析了高频变压器的设计要点.结果分析表明:该变换...     

煤矿井下安全监控分站的设计及其仿真实现

为了设计一种具有低成本、低功耗、易操作、功能强且可靠性高的煤矿井下安全分站,针对煤矿安全生产实际,文章提出了采用MCS-51系列单片机为核心、具有CAN总线通信接口的煤矿井下安全监控分站的设计方案;首先给出煤矿井下安全监控分站的整体构架设计,然后着重阐述模拟量输入信号处理系统的设计过程,最后说明单片机最小系统及其键盘、显示、报警、通信等各个组成部分的设计;为验证设计方案的可行性与有效性,使用Proteus软件对设计内容进行仿真验证,设计的煤矿井下安全监控分站具有瓦斯、温度等模拟量参数超标报警功能和电机开停、风门开闭等开关量指示功能;仿真结果表明:设计的煤矿井下安全监控分站具有一定的实际应用价值.     

View-based model-driven architecture for enhancing maintainability of data access services

In modern service-oriented architectures, database access is done by a special type of services, the so-called data access services (DAS). Though, particularly in data-intensive applications, using and developing DAS are very common today, the link between the DAS and their implementation, e.g. a layer of data access objects (DAOs) encapsulating the database queries, still is not sufficiently elaborated, yet. As a result, as the number of DAS grows, finding the desired DAS for reuse and/or associated documentation can become an impossible task. In this paper we focus on bridging this gap between the DAS and their implementation by presenting a view-based, model-driven data access architecture (VMDA) managing models of the DAS, DAOs and database queries in a queryable manner. Our models support tailored views of different stakeholders and are scalable with all types of DAS implementations. In this paper we show that our view-based and model driven architecture approach can enhance software development productivity and maintainability by improving DAS documentation. Moreover, our VMDA opens a wide range of applications such as evaluating DAS usage for DAS performance optimization. Furthermore, we provide tool support and illustrate the applicability of our VMDA in a large-scale case study. Finally, we quantitatively prove that our approach performs with acceptable response times.     

A pragmatic multi-method investigation of discrepant technological events: Coping,attributions, and ‘accidental’ learning

Discrepant technological events or situations that entail a problem, a misunderstanding or a difficulty with the Information Technology (IT) being employed, are common in the workplace, and can lead to frustration and avoidance behaviors. Little is known, however, about how individuals cope with these events. This paper examines these events by using a multi-method pragmatic approach informed by coping theory. The results of two studies – a critical incident study and an experiment – serve to build and test, respectively, a theoretical model that posits that individuals use a variety of strategies when dealing with these events: they experience negative emotions, make external attributions, and adopt engagement coping strategies directed at solving the event, eventually switching to a disengagement coping strategy when they feel they have no control over the situation. Furthermore, users’ efforts may result in ‘accidental’ learning as they try to overcome the discrepant IT events through engagement coping. The paper ends with a discussion of the results in light of existing literature, future opportunities for research, and implications for practice.     

The Distributed Time-Triggered Simulation Scheme: Core Principles and Supporting Execution Engine

Distributed real-time simulation is a young technology field but its practice is under increasing demands. In recent years the author and his collaborators have been establishing a new approach called the distributed time-triggered simulation (DTS) scheme which is conceptually simple and easy to use but widely applicable. The concept was initiated in the course of developing a new-generation object-oriented real-time programming scheme called the time-triggered message-triggered object (TMO) programming scheme. Some fundamental issues inherent in distributed real-time simulation that were learned during recent experimental studies are discussed along with some approaches for resolving the issues. An execution engine developed to support both the TMOs engaged in control computation and the TMOs engaged in DTS is also discussed along with its possible extensions that will enable significantly larger-scale DTSs.     

Software-Konfigurationsmanagement in großen Softwareprojekten

Zusammenfassung Mit zunehmender Größe der Softwaresysteme verschärfen sich die für die Software-Herstellung typischen Probleme: Beherrschen großer Objektmengen, Erhalten der Systemkonsistenz, Kontrolle der ständigen Änderungseinflüsse und Gewährleisten einer langen Lebensdauer. Die Disziplin Konfigurationsmanagement bildet den methodischen Ansatz, diese Probleme besser zu beherrschen. Software-Konfigurationsmanagement faßt die Herstellung von Softwaresystemen als eine Abfolge von kontrollierten Änderungen an gesicherten Zwischen- und Endergebnissen auf. Dargestellt werden die Objekte und Funktionen des Software-Konfigurationsmanagements sowie die hierfür in großen Software-Projekten benötigten Methoden, Instanzen und Hilfsmittel.     

Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and     

Editorial:Brain-machine interface(BMI) and cyborg intelligence

正Brain-machine interfaces(BMIs)aim at building a direct communication pathway between the brain and an external device,and represent an area of research where significant progress has been made during the past decade.Based on BMIs,mind information can be read out by neural signals to control     

Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and overseas to the world’s scientific circles,especially to stimulate     

SCIENCE CHINA Information Sciences SUBJECT INDEX TO VOLUME 57(2014)

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Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and overseas to the world’s scientific circles,especially to stimulate