热电偶毫伏信号发生器的设计与实现

设计了一种热电偶毫伏信号发生器,利用上位机软件LabVIEW的计算优势,将所需的温差转化为相应的热电动势大小,并通过USB或串口发送到单片机,由单片机控制12位DAC转换电路输出相应的电压。测试表明,采用此种方法可以方便地实现多种类型的热电偶信号产生,精度可达±0.1℃,适用于一般的热电偶测量仪表的校准,并且可以根据需要对温度范围进行调节,同时支持多路独立输出,提高了校准效率。     

基于PIC单片机的热膜式空气流量计设计

介绍了一种基于PIC单片机的数字输出型热膜空气流量计,用于汽车进气流量的检测.首次提出以PIC单片机为流量计控制核心,充分利用单片机内部的ADC、CCP、PSMC等硬件资源,实现了热膜传感单元输出模拟信号的采集、模数转化,以及流量信号、温度信号的输出控制等功能.针对热膜传感单元流量信号存在对环境温度交叉敏感等问题,提出一种基于二元回归分析法的热膜式流量计的校准方法,并详细介绍了流量计的自校准过程.     

基于MAX6675的烘炉温度追踪仪的研究及设计

为提高烘炉温度检测技术水平，对烘炉温度追踪仪进行了研究。系统采用了高精度热电偶数字转换器芯片MAX6675。该芯片具有热电偶冷端补偿、非线性校正、断线检测等多种功能，并能对热电偶测温信号进行A／D转换，使系统的硬件结构大为简化。测温精度得到了提高。烘炉温度测量采用89C55单片机进行控制，通过RS-232接口进行数据传送。实践表明：该装置的研制对改造和优化追踪仪的工艺流程等将发挥重要的作用。     

基于单片机的蓄电池温度数据采集系统

为了时蓄电池的温度进行检测。数据采集是必不可少的手段。程序控制数据采集系统是比较先进的采集方式，本文采用热电偶为温度检测元件时蓄电池温度信号进行采集来构建单片机温度采集系统，较好的实现了所需目的。     

嵌入式发动机活塞温度测试系统设计

针对发动机活塞温度缺乏有效的测试手段,设计了一种嵌入式活塞温度测试系统;选用K型热电偶作为温度传感器,利用AD590配合2.5V基准电压源输出补偿电势对热电偶冷端温度进行了补偿,通过调节AD8495设定点电压在预设温度下输出上升沿实现了可调触发温度功能;系统在PIC单片机控制下通过内置模数转换器(ADC)采集活塞顶部3个测点的温度数据后,通过CC2530将测试结果发送至上位机接收平台;测试前在高温箱内对系统进行了标定,将实测值与标定值进行了对比并在发动机台架上进行了试验;实测结果表明:系统测量误差为±1℃,在130℃的高温环境下仍能正常工作,具有良好的稳定性和可靠性。     

热电偶冷端温度智能补偿与检测

介绍了具有热电偶冷端温度智能补偿的温度检测系统的组成和功能 ,重点阐述了以单片机为核心构成热电偶冷端温度智能补偿的原理和特点 ,说明了软件功能。最后给出了实践结果及主要性能指标。     

基于PIC单片机的本质安全型电流-频率转换电路设计

针对模拟量传感器的信号输出形式存在多样性的问题,设计了一种基于PIC单片机的本质安全型电流-频率转换电路。该电路采用本质安全电源供电,将模拟量电流信号经高精度采样电阻接地转换为电压信号并送入PIC单片机的A/D采样口,由软件处理后转换为频率信号。实际应用表明,该电路能满足各种电流型传感器方便接入煤矿安全监控系统的需求。     

基于CAN总线的镀锌池温度测控系统

通过对镀锌池温度技术指标进行分析,设计基于CAN总线的镀锌池温度远程测控系统:本系统微控制器采用ATMEL公司的AT89S52单片机,利用K型热电偶进行温度信号采集:利用具有冷端补偿的单片K型热电偶放大器与数字转换器MAX6675进行温度信号调理:通过模糊PID参数自整定方法进行温度控制.系统利用CAN总线实现数据的远程传输并通过串口与上位机进行通信,实现对被测对象的温度进行远程监视和控制.实际测试表明,系统完全满足精度及可靠性等方面要求.     

一种热电偶温度传感器信号模拟装置设计

热电偶温度传感器具有结构简单、可靠性高、测量范围宽等优点,广泛应用于现代燃气涡轮发动机温度测量.本文设计了一种热电偶信号模拟装置,可根据通讯输入的热端温度和冷端温度数字信号精确地生成热电偶输出信号,并提供与真实传感器一致的电气接口特性.文章对信号模拟装置的工作原理和电路设计进行了阐述,对设计符合性进行了分析,表明信号模...     

基于单片机的多点温度测量仪的设计

提出一种以热敏电阻为温度传感器,经电阻-脉宽转换电路将热敏电阻的输出转换为脉宽信号,再由PIC16F876单片机进行处理,以实现多点温度显示的温度测量仪.采用比较法消除了电阻-脉宽转换电路由于器件参数变化造成的测量误差,提高了测量精度.该多点温度测量仪具有数字显示温度和以RS232串口输出温度的功能.     

Call for Papers The 6^th International Conference on Grid and Cooperative Computing

Recent years have seen rapid advances in various grid-related technologies, middleware, and applications. The GCC conference has become one of the largest scientific events worldwide in grid and cooperative computing. The 6th international conference on grid and cooperative computing (GCC2007) Sponsored by China Computer Federation (CCF),Institute of Computing Technology, Chinese Academy of Sciences (ICT) and Xinjiang University ,and in Cooperation with IEEE Computer Soceity ,is to be held from August 16 to 18, 2007 in Urumchi, Xinjiang, China.     

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.     

法律信息库系统

本文分析了法律数据库的结构和特点，介绍了采用面向对象设计方法和超文本数据库技术开发和实现法律信息库系统将作为重要网络资源之一为不同用户进行法律咨询服务。     

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.     

International Journal of Automation and Computing Table of Contents

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Information for authors

正SCIENCE CHINA Information Sciences(Sci China Inf Sci),cosponsored by the Chinese Academy of Sciences and the National Natural Science Foundation of China,and published by Science China Press,is committed to publishing highquality,original results of both basic and applied research in all areas of information sciences,including computer science and technology;systems science,control science and engineering(published in Issues with odd numbers);information and communication engineering;electronic science and technology(published in Issues with even numbers).Sci China Inf Sci is published monthly in both print and electronic forms.It is indexed by Academic OneFile,Astrophysics Data System(ADS),CSA,Cabells,Current Contents/Engineering,Computing and Technology,DBLP,Digital Mathematics Registry,Earthquake Engineering Abstracts,Engineering Index,Engineered Materials Abstracts,Gale,Google,INSPEC,Journal Citation Reports/Science Edition,Mathematical Reviews,OCLC,ProQuest,SCOPUS,Science Citation Index Expanded,Summon by Serial Solutions,VINITI,Zentralblatt MATH.     

Erratum to: Fast global kernel fuzzy c-means clustering algorithm for consonant/vowel segmentation of speech signal

正Erratum to:J Zhejiang Univ-Sci C(ComputElectron)2014 15(7):551-563doi:10.1631/jzus.C1300320The original version of this article unfortunately contained mistakes.Algorithm 6 should be as follows:Algorithm 6 FGKFCM-F clustering Input:(1)X={x_1,x_2,…,x_N},,x_iR~d,i=1,2,…,N,the dataset;(2)C,1C≤N,the number of clusters;(3)ε0,the stopping criterion;     

Journal of Zhejiang University-SCIENCE C (Computers & Electronics) Total contents

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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.