工业自动化控制系统的抗干扰技术分析

分析了干扰感应模型,指出常见的工业自动化控制系统的干扰源包括辐射干扰、传导干扰和设计施工引起的干扰,分析了这些干扰的产生机理;指出应从设计和现场施工两方面采取抗干扰措施,设计阶段要考虑电源设计、接地系统设计、管线设计、器件选择、软件设计等因素,并给出了常见的抗干扰措施;以某燃气站控制系统为例介绍了抗干扰措施在实际工业现场中的应用方案,验证了合理的抗干扰措施可有效降低干扰,保证工业自动化控制系统的可靠运行。     

计算机应用中几种有效的抗干扰措施

针对计算机在冶金矿山应用中常遇到的抗干扰问题，分类进行了分析，并提出了措施。首先从设备的选型上着手，集资对由电源引入的干扰，由输入／输出信号线路引入的干扰，提出了相应的几种有效防干扰措施，而且从接地抗干扰和软件抗上阐述了明确有效的抗干扰方法和措施。另外，对于一些特殊的低频干扰、高频干扰、脉冲干扰和周期性干扰也提出了相应的处理手段。同时还介绍了一实际的计算机系统使用本文提出的抗干扰措施的效果。     

DZC-3000型工业称量仪抗干扰措施

为解决DZC-3000型工业称量仪在恶劣的工业环境中受到干扰问题,在分析系统可能受到供电电源、系统输入输出通道、外界对CPU干扰等各种干扰的基础上,提出了软硬件方面的各种抗干扰措施,重点分析了SMR软件抗干扰措施。当程序运行脱离正常运行流程时,使用SMR抗干扰措施可使PC进入复位入口,并从受干扰处重新按原流程运行。     

基于单片机的高压开关智能保护器的抗干扰设计

文章从多个角度分析了基于单片机的高压智能保护器的干扰来源并指出了干扰的危害性,从硬件和软件2个方面给出了相应的抗干扰措施。这些抗干扰措施应用在BZGK2H型高压开关智能综合保护器上取得了良好的抗干扰效果。     

微型机实时控制系统中的抗干扰问题

微型机用于工业控制中的抗干扰问题是个极为重要的问题,本文从干扰窜入系统的三条路径谈起,具体阐述了供电系统,过程通道中的抗干扰措施;空间干扰,地线系统抗干扰的设计以及软件的抗干扰问题。在现场的一个实时控制系统中,若采用了本文阐述的若干抗干扰措施,系统一定能成功稳定的运行。     

抗干扰技术在煤矿单片机测控系统中的应用

针对单片机测控系统的工作稳定性经常受到各种干扰影响的问题,分析了干扰来源、干扰因素及其产生的后果,详细介绍了针对这些干扰所采取的硬件及软件抗干扰措施,并以煤层注水流量测控仪为例,介绍了上述硬件及软件抗干扰措施在该测控仪中的应用。     

PLC控制系统受到的干扰分析

主要介绍了PLC控制系统在工业应用中可能受到的干扰类型,提出了针对性的抗干扰措施,并强调了在系统设计和安装时,必须对环境作全面的分析,确定干扰的性质,采取相应的抗干扰措施。     

PLC应用系统的抗电磁干扰研究

阐述了PLC应用系统存在的主要电磁干扰,针对电磁干扰的不同途径,论及了电源抗干扰设计措施和输入输出电路抗干扰设计措施,分析了合理布线抑制辐射型干扰以及完善接地系统抑制接地干扰的具体措施。     

单片机系统硬件抗干扰设计

本文探讨了单片机控制系统的硬件抗干扰设计，着重了电源抗干扰和传输线干扰及其抗干扰措施。     

电网智能模糊控制器的干扰源分析及屏蔽

电网智能模糊控制器由于应用于高电压及复杂电磁环境场合,必须准确分析电磁干扰源并设计屏蔽干扰的措施,才能保证设备的安全运行.本文首先讨论了外部骚扰源的产生原因,着重介绍防静电放电(ESD)干扰措施,防辐射电磁场干扰措施,抗衰减振荡波干扰措施,抗浪涌(冲击)干扰措施,抗快速瞬变脉冲群干扰措施.并提供了在实验结果的基础上改进的方法.其次讨论了内部骚扰源抗干扰设计时着重考虑的问题,对软件抗干扰的设计做了简要说明.     

Production control: Current developments and future trends

Manufacturing industry is going through a period of unprecedented change as a result of the developments in micro-electronic technology. This is bringing about a transformation not only in hardware, in the form of computer-aided manufacturing, but in the manner in which production is organised and controlled.It is in the latter connection that the present paper sets out to review current developments and future trends. In particular the machine readable bar-code is seen as a key element in extending computerised control to cover not only the machines, but tools, materials and parts and their movement in the development of fully integrated manufacturing systems.As the move towards automation gathers pace it is forecast that manufacturing industry will become more process industry like in form, with consequences for the way in which production is organised and controlled.Finally consideration is given to the manner in which these current developments in the field of production are giving rise to a structural alteration in industrial labour requirements in which, in the future, fewer people will be required but on highly enriched work tasks.     

Methods of system development in Finland

Interest in the use of different methodologies, methods and tools for information systems analysis and design has been increasing for the last decade in Finland. This has resulted in the founding of a special interest group in systems analysis and design within the Finnish Data Procesing Association and in its making a survey of the methods and tools in use in Finland in 1980. This survey was in the form of a questionnaire mailed to the company members of the association. The results of the survey show a wide use of different tools in the design and implementation of information systems. In the analysis phase, there seems to be a need for more and better methods and tools. In 1980 several companies began to use new methodologies, methods and tools in the field; the most common are: the Swedish ISAC, Jackson's JSP, and the data dictionary.     

The Old-Age Healthy Dependency Ratio in Europe

The aim of this study is to answer the question of whether improvements in the health of the elderly in European countries could compensate for population ageing on the supply side of the labour market. We propose a state-of-health-specific (additive) decomposition of the old-age dependency ratio into an old-age healthy dependency ratio and an old-age unhealthy dependency ratio in order to participate in a discussion of the significance of changes in population health to compensate for the ageing of the labour force. Applying the proposed indicators to the Eurostat's population projection for the years 2010-2050, and assuming there will be equal improvements in life expectancy and healthy life expectancy at birth, we discuss various scenarios concerning future of the European labour force. While improvements in population health are anticipated during the years 2010-2050, the growth in the number of elderly people in Europe may be expected to lead to a rise in both healthy and unhealthy dependency ratios. The healthy dependency ratio is, however, projected to make up the greater part of the old-age dependency ratio. In the European countries in 2006, the value of the old-age dependency ratio was 25. But in the year 2050, with a positive migration balance over the years 2010-2050, there would be 18 elderly people in poor health plus 34 in good health per 100 people in the current working age range of 15-64. In the scenarios developed in this study, we demonstrate that improvements in health and progress in preventing disability will not, by themselves, compensate for the ageing of the workforce. However, coupled with a positive migration balance, at the level and with the age structure assumed in the Eurostat's population projections, these developments could ease the effect of population ageing on the supply side of the European labour market.     

Syntactic Positions of Prepositional Phrases in the History of Chinese: Using the Developing Sheffield Corpus of Chinese for Diachronic Linguistic Studies

This paper reports the completion of the first expansion phaseof the Sheffield Corpus of Chinese (SCC). We describe the majorimprovements we made in expanding the corpus. They involve thecoverage of time periods, choice of text types and categories,and selection of individual texts; the mark up scheme and theintegral search and analysis tool. We use the developing SCCto examine Li and Thompson's; (1974, 1975, 1976) controversialpostverbal predominance hypothesis for prepositional phrases(PPs) in Archaic Chinese and their word order change hypothesisfor PPs in general in the history of the Chinese language. Ourstudy provides no evidence for the postverbal predominance hypothesisfor PPs in Archaic Chinese and the word order change hypothesisfor PPs in general from postverbal in Archaic Chinese to preverbalin Modern Chinese. Our findings show that postverbal and preverbalPPs have been in coexistence and there have always been moreoccurrences of preverbal PPs than postverbal PPs in all thetime periods covered in the current SCC. Although use of somePPs declined in some time periods and use of others emergedin other time periods, there was never a predominant positionfor PPs in any time period in the history of Chinese. We showdifferences in the distribution of PPs in different time periodsand provide an account of the syntactic positions of PPs inthose time periods.     

RAID控制器中磁盘接口控制器流水线设计与实现

在研究磁盘接口功能和现有磁盘接口设计的基础上,提出了一种带四级流水的磁盘接口设计模型,并对该模型实现过程中的模块间通信问题和模块间缓冲管理问题进行了相应的分析和设计。通过FPGA仿真与实验结果表明,在各种情况下,磁盘接口的吞吐率都有提高,在高写请求率和重负载两种情况下尤为显著。     

判别线面相交及面面相交可见性的假想墙法

针对判别直线与平面相交及平面与平面相交的可见性提出了一种假想墙的方法。 在直线与平面相交问题中探讨了 3 种典型的情况：一般位置直线与特殊位置平面相交、一般位 置直线与一般位置平面相交、特殊位置直线与一般位置平面相交;在平面与平面相交的问题中 探讨了 3 种典型的情况：特殊位置平面与特殊位置平面相交、一般位置平面与特殊位置平面相 交、一般位置平面与一般位置平面相交。通过假想墙方法,可快速准确地判断直线与平面相交 及平面与平面相交的可见性,为机械制图课程相关内容的学习及教学提供一些参考。     

Adaptive solutions to the mutual exclusion problem

Summary Algorithms for mutual exclusion that adapt to the current degree of contention are developed. Afilter and a leader election algorithm form the basic building blocks. The algorithms achieve system response times that are independent of the total number of processes and governed instead by the current degree of contention. The final algorithm achieves a constant amortized system response time. Manhoi Choy was born in 1967 in Hong Kong. He received his B.Sc. in Electrical and Electronic Engineerings from the University of Hong Kong in 1989, and his M.Sc. in Computer Science from the University of California at Santa Barbara in 1991. Currently, he is working on his Ph.D. in Computer Science at the University of California at Santa Barbara. His research interests are in the areas of parallel and distributed systems, and distributed algorithms. Ambuj K. Singh is an Assistant Professor in the Department of Computer Science at the University of California, Santa Barbara. He received a Ph.D. in Computer Science from the University of Texas at Austin in 1989, an M.S. in Computer Science from Iowa State University in 1984, and a B.Tech. from the Indian Institute of Technology at Kharagpur in 1982. His research interests are in the areas of adaptive resource allocation, concurrent program development, and distributed shared memory.A preliminary version of the paper appeared in the 12th Annual ACM Symposium on Principles of Distributed ComputingWork supported in part by NSF grants CCR-9008628 and CCR-9223094     

A new mining approach for uncertain databases using CUFP trees

In the past, many algorithms have been proposed to mine frequent itemsets from transactional databases, in which the presence or absence of items in transactions was certainly known. In some applications, items may also be uncertain in transactions with their existential probabilities ranging from 0 to 1 in the uncertain dataset. Apparently, the processing in uncertain datasets is quite different from those in certain datasets. The UF-tree algorithm was proposed to construct the UF-tree structure from an uncertain dataset and mine frequent itemsets from the tree. In the UF-tree construction process, however, only the same items with the same existential probabilities in transactions were merged together in the tree, thus causing many redundant nodes in the tree. In this paper, a new tree structure called the compressed uncertain frequent-pattern tree (CUFP tree) is designed to efficiently keep the related information in the mining process. In the CUFP tree, the same items will be merged in a branch of the tree even when the existential probabilities in transactions are not the same. A mining algorithm called the CUFP-mine algorithm is then proposed based on the tree structure to find uncertain frequent patterns. Experimental results show that the proposed approach has a better performance than UF-tree algorithm both in the execution time and in the number of tree nodes.     

INTRODUCTION TO THE SPECIAL ISSUE ON CASE-BASED REASONING IN THE HEALTH SCIENCES

There has been an explosion of interest in health sciences applications of case-based reasoning (CBR), not only in the traditional CBR in medicine domain, but also in bioinformatics, enabling home health-care technologies, CBR integration, and synergies between CBR and knowledge discovery. This special issue features the best papers from the third workshop on CBR in the health sciences, held at ICCBR-05 in Madrid. It is the third in a series of exciting workshops, the first two of which were held at ICCBR-03, in Trondheim, Norway, and at ECCBR-04, in Madrid, Spain. The nine high-quality papers introduced here represent the research and experience of twenty-two authors working in eight different countries on a wide range of problems and projects. These papers illustrate some of the major trends of current research in CBR in the health sciences, and represent overall an excellent sample of the most recent advances of CBR in the health sciences.     

The application of IT in organisations: Some trends and issues

Abstract

This paper describes some trends and issues in the application of information technology in organisations. Technology trends are outlined in the areas of computing power, telecommunications, networking, software and standards. Some trends in the applications of IT are described with respect to developments in information systems and office automation. Some differences in the likely role of IT in the industrialised and developing countries are discussed. The second half of the paper deals with issues in the management of IT applications in organisations, and issues are identified as being political, organisational and social in nature in addition to technical. A social systems framework is proposed for the analysis of these issues. Some specific IT issues are then discussed involving alternative stakeholder perspectives, the analysis of decision making processes, the process of consultation and communication and the organisational impacts of IT applications.