冷库温度控制系统的设计-外文翻译.doc

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1、大连交通大学信息工程学院2012届本科生毕业设计（论文）外文翻译大连交通大学信息工程学院毕业设计(论文)外文翻译学生姓名1111专业班级自动化0111班指导教师1111职称　11111所在单位电气工程系教研室主任　完成日期1111年4月13日15大连交通大学信息工程学院2012届本科生毕业设计（论文）外文翻译DateAcquisitionDateacquisitionsystemsareusedtoacquireprocessoperatingdataandstoreitonsecondarystoragedevicesforlateranalysis.

2、Manyofthedataacquisitionsystemsacquirethisdataatveryhighspeedsandverylittlecomputertimeislefttocarryoutanynecessary,ordesirable,datamanipulationsorreduction.Allthedataarestoredonsecondarystoragedevicesandmanipulatedsubsequentlytoderivethevariablesofinterest.Itisveryoftennecessary

3、todesignspecialpurposedataacquisitionsystemsandinterfacestoacquirethehighspeedprocessdata.Thisspecialpurposedesigncanbeanexpensiveproposition.Powerfulmini-andmainframecomputersareusedtocombinethedataacquisitionwithotherfunctionssuchascomparisonsbetweentheactualoutputandthedesirab

4、leoutputvalues,andtothendecideonthecontrolactionwhichmustbetakentoensurethattheoutputvariablesliewithinpre-setlimits.Thecomputingpowerrequiredwilldependuponthetypeofprocesscontrolsystemimplemented.Softwarerequirementsforcarryingoutproportional,ratioorthreetermcontrolofprocessvari

5、ablesarerelativelytrivial,andmicrocomputerscanbeusedtoimplementsuchprocesscontrolsystems.Itwouldnotbepossibletousemanyofthecurrentlyavailablemicrocomputersfortheimplementationofhighspeedadaptivecontrolsystemswhichrequiretheuseofsuitableprocessmodelsandconsiderableon-linemanipulat

6、ionofdata.Microcomputerbaseddataloggersareusedtocarryoutintermediatefunctionssuchasdataacquisitionatcomparativelylowspeeds,simplemathematicalmanipulationsofrawdataandsomeformsofdatareduction.Thefirstgenerationofdataloggers,withoutanyprogrammablecomputingfacilities,wereusedsimplyf

7、orslowspeeddataacquisitionfromuptoonehundredchannels.Alltheacquireddatacouldbepunchedoutonpapertapeorprintedforsubsequentanalysis.Suchhardwireddataloggersarebeingreplacedbythenewgenerationofdataloggerswhichincorporatemicrocomputersandcanbeprogrammedbytheuser.Theyofferanextremelyg

8、oodmethodofcollectingtheprocessdata,usin