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本文详细论述了德国海德海因(HEIDENHAIN)公司ROD800圆光栅的结构、工作原理,以及与它一起组成数控机床回转工作台位置检测系统的脉冲整形倍频器电路和数控部分的四倍频电路工作原理,并探讨了光栅测量系统故障的查寻及排除方法。 相似文献
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简扼地介绍了AutoMax DCS控制系统模块化的结构,各模块的功能特点,系统分时多任务的工作方式。基于Windows环境的集成编程控制系统以及系统的维护和改造。重点强调了系统硬软件的易维护、故障诊断功能、在线监控功能及系统改造的特点。 相似文献
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石油化工企业普遍采用的分散控制系统(DCS)系统,为操作人员监控工艺过程提供了有力保障,DCS在报警方面的强大功能,为生产过程的安全运行起到了重大的作用。在DCS中,几乎每一个组态点都可以设置多个报警(一个PID回路通常可设置测量报警、偏差报警、BADPV等10多个报警),通常,一个普通操作员在操作波动的情况下,每一分钟只能处理一个报警,报警点的过度设置,不 相似文献
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自动化生产企业基本配置现代企业,工厂自动化是世界潮流,大势所趋。工厂自动化可用"点、线、面"三级层面来概括,其中"面"级自动化系指计算机生产管理系统(Production Management System,简称PMS);"线"级自动化系指生产线设备计算机分级分布控制系统(Distributed Control System,简称DCS);"点"级自动化系指隶属于生产线的单元机设备现场计算机控制盘系统(Local Control Panel,简称LCP)。一套PMS可包括多种多条DCS,一条DCS可包括多种多台 相似文献
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大型火电厂采用分散控制系统(DCS)进行生产过程监控,可减少系统设备和人员的重复设置,有利于集中监控和故障分散,是保证机组安全运行、稳发满发的重要条件.本文从设备安装角度,介绍了来宾B厂作为广西第一台300 MW以上大型机组,采用DCS系统的硬件结构、系统功能和系统设备. 相似文献
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为保证印刷电路板组件(printed circuit board assembly,PCBA)的功能性完备,在装壳前需对其进行功能测试,而当前生产线主要由人工测试分拣,效率低下,为此,设计了一种能够自动扫码、测试、分拣的自动控制系统。选用西门子S7-1200PLC作为控制器,WinCC组态软件作为上位监控系统,PLC与WinCC之间采用OPC的方式实现通信,采用VBS编程调用MSComm控件实现WinCC与测试工装和扫码枪之间的串口通信。测试结果表明,系统运行稳定,具有很好的实用性、可靠性。系统的使用能减少人力的投入,降低操作人员的劳动强度,提高生产效率,可在PCBA模块生产线中广泛使用。 相似文献
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Experience has shown that a Distributed Control System (DCS) can provide enhanced process monitoring and control capabilities, as well as system self-diagnostics, that permit increased safety of process operations. However, this enhanced safety does not come about automatically with the installation of a DCS. The complexity and versatility of the DCS can introduce new failure scenarios leading to process upset and potential relization of process hazards. This paper reviews some novel considerations that should be taken into account when conducting process hazards reviews on facilities controlled by a DCS. 相似文献
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This paper presents the results of a generic reliability analysis of fault-tolerant digital control systems (F-T DCS). This analysis differs from previous efforts at estimating the reliability performance of F-T DCS in the sense that this analysis relies extensively on actual experience with redundant computer systems rather than on theoretical evaluations. The dominant contributors to the frequency of failure of F-T DCS are (1) failures within common or shared equipment, (2) software failures, and (3) inadvertent operator actions. Other contributors include loss of electric power, spurious signals that originate from within the DCS, lack of coverage, common cause failure (CCF) of redundant hardware, CCF of instrument channels, and physical damage from externally initiated events (e.g., high temperature). Much variation is expected in the reliability performance of F-T DCSs. Although some systems may operate for 10 or 15 years without experiencing system failures, other systems may fail several times during the same time interval. This variation is expected among systems of different architectures as well as among systems of the same architecture. Because most failures of DCSs can be traced to some kind of CCF, particularly software failures and inadvertent operator actions, CCFs should probably receive more attention than they are presently given when selecting an F-T DCS. 相似文献
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测试用例的设计和编制是软件质量稳定的根本保障,完善测试平台,规范测试步骤,具有完整的测试大纲及用例集,对测试的完整性有重要的意义。本文主要对基于SAC型电液控制系统的测试用例集的构建方法和测试内容展开研究,介绍了SAC型电液控制系统的组成及系统可以实现的功能,主要阐述了基于此系统的测试平台的搭建、测试流程中的主要步骤并举例说明以及系统安全性测试方法。 相似文献
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Kevin Ibeh Author Vitae Jürgen Kai-Uwe Brock Author Vitae Yu Josephine Zhou Author Vitae 《Industrial Marketing Management》2004,33(2):155-165
This paper examines the effectiveness of drop-and-collect-survey (DCS) method in improving response rates among organisations. It proposes a theory for its effectiveness and advances a number of propositions relating to its usage among organisations. Subsequent analyses, using empirical evidence from two separate DCS-based studies in Nigeria and Germany, suggest that the DCS results in significantly higher response rates among organisational respondents compared to mail questionnaires. These improved response rates are more likely to be achieved among smaller organisations and through direct, face to face, contact with the target key informant. Combining DCS with prenotification showed only a small, but positive effect. Support was also found for the hypothesised greater effectiveness of the DCS among high-technology firms relative to their low-technology counterparts. Based on the proposed theory and the empirical findings, a DCS decision and implementation framework is presented and directions for future research suggested. 相似文献
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稠油降粘剂降粘效果测定标准的探讨 总被引:5,自引:0,他引:5
叙述了降粘剂的作用机理以及目前测定降粘效果的方法的现状;讨论了对测定降粘效果的温度控制、原油取样控制、加药浓度控制等条件的原由;分析了测定用粘度计的选择及降粘效果的表示与确定.认为,应统一降粘剂效果测定标准,按照SY/T0520-93%测定稠油降粘剂粘度. 相似文献
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迄今为止作为现代先进的计算机监控系统——分散控制系统还没有在核电站中被广泛应用。岭澳核电站常规岛部分大胆使用先进的 P32 0分散控制系统作为其主要控制手段 ,在国内引起了广泛的关注。本文主要介绍了P32 0分散控制系统的结构、工作原理、通讯、在岭澳核电站常规岛的应用情况及其存在的不足和缺陷 相似文献