火灾报警器中英文文献翻译

1外文文献原稿和译文原稿Multiplesingle-chipmicrocomputerapproachtofiredetectionandmonitoringsystemA.J.AI-Khalili,MSc,PhDD.AI-Khalili,MSc,PhDM.S.Khassem,MScIndexingterm:Hazards,Design,PlantconditionmonitoringAbstract:Acompletesystemforfiredetectionandalarmmonitoringhasbeenproposedforcomplexplants.Thesystemusesmultiplesinglechiparchitectureattachedtoapartyline.Thecontrolalgorithmisbasedonatwo-levelhierarchyofdecisionmaking,thusthecomplexityisdistributed.Acompletecircuitdiagramisgivenforthelocalandthecentralstationwithrequirementsforthesoftwarestructure.Thedesigniskeptingeneralformsuchthatitcanbeadaptedtoamultitudeofplantconfigurations.Itisparticularlyshownhownewdevelopmentsintechnology,especiallyCMOSsinglechipdevices,areincorporatedinthesystemdesigntoreducethecomplexityoftheoverallhardware,e.g.bydecomposingthesystemsuchthatlowerlevelsofhierarchyareabletohavesomeautonomyindecisionmaking,andthusamorecomplexdecisionissolvedinasimpledistributedmethod.1DetectionandalarmdevicesAbasicfiredetectionsystemconsistsoftwoparts,detectionandannunciation.Anautomaticdetectiondevice,suchasaheat,smokeorflamedetector,ultravioletor2infrareddetectorsorflameflicker,isbasedondetectingthebyproductofacombustion.Smokedetectors,ofbothionizationandopticaltypes,arethemostcommonlyuseddetectordevices.WhenatypicaldetectorofthistypeentersthealarmstateitscurrentconsumptionincreasesfromthepAtothemArange(say,fromamere15pAinthedormantmodeto60mA)intheactivemode.Inmanydetectorsthedetectoroutputvoltageiswelldefinedundervariousoperatingconditions,suchasthosegiveninTable1.Themoresensitivethedetector,themoresusceptibleitistofalsealarms.Inordertocontrolthedetectorprecisely,eitherofthefollowingmethodsisused:acoincidencetechniquecanbebuiltintothedetector,orafilteringtechniquesuchthatalogiccircuitbecomesactiveonlyifxalarmsaredetectedwithinatimeperiodT.Thedetectiontechniquedependsgreatlyonthelocationandplantbeingprotected;smokedetectorsareusedforsleepingareas,infraredorultravioletradiationareusedwhenflammableliquidsarebeinghandled,heatdetectorsareusedforfiresuppressionorextinguishingsystems.Ingeneral,lifeandpropertyprotectionhavedifferentapproaches.Alarmdevices,apartfromtheusualaudibleorvisiblealarms,mayincorporatesolidstatesoundreproductionandemergencyvoicecommunicationorprintersthatrecordtime,date,locationandotherinformationrequiredbythestandardcodeofpracticeforfireprotectionforcomplexplants.Heaviside[4]hasanexcellentreviewofalltypesofdetectorsandextinguishersystems.1.1ControlphilosophyanddivisionoflabourOurcontrolphilosophyisimplementedhierarchically.Threelevelsofsystemhierarchyareimplemented,withtwolevelsofdecisionmaking.Thereisnocommunicationbetweenequipmentonthesamelevel.Interactionbetweenlevelsoccursbyupwardstransferofinformationregardingthestatusofthesubsystemsanddownwardstransferofcommands.ThisisshowninFig.1whereatlevel1isthe3centralstationmicrocomputerandistheultimatedecisionmaker(whennotinmanualmode).Atlevel2arethelocalcontrollers,whichresideinthelocalstations.Atlevel3aretheactualdetectorsandactuators.Amanualmodeofoperationisprovidedatalllevels.Informationregardingthestatusofalldetectorsistransmittedonaperareabasistothelocalcontrollers.Theirinformationiscondensedandtransmittedupwardtothecentralmicrocomputer.Transferofstatusisalwaysunidirectionalandupwards.Transferofcommandsisalwaysunidirectionalanddownwards,withexpansionatthelocalcontrollevel.Thisapproachpreservesthestrictrulesofthehierarchyforexactmonitoringdetectionandalarmsystemsassociatedwithhighriskplants.Theclassificationofthetwolayersofcontrolsisbaseduponlayersofdecisionmaking,withrespecttothefactsthat(a)Whenthedecisiontimecomes,themakingandimplementationofadecisioncannotbepostponed(b)Thedecisionshaveuncertainty(c)Itwillisolatelocaldecisions(e.g.locallywemighthaveanalarmalthoughtheremaybeafaultwiththesystem)2Generalhardware4I:Fig.2depictsourdesigninthesimplestofforms.Thesystemusesanopenpartylineapproachwithfourconductorcablesgoinginaloopsharedbyalltheremotedevicesandthecontrolpanel.Thisapproachissimpleinconceptandiseconomicallyfeasible.However,onemajordisadvantageisthedependencyonasinglecableforpowerandsignaling.Incaseswherereliabilityisofextremeimportance,twooreventhreecablestakingdifferent5routesthroughoutthesystemmaybeconnectedinparallel.Fig.3givesthedrivercircuitryrequiredtoderiveanexpandablebus.Thisdesigntakesadvantageofrecentadvancesinthesinglechipmicrocomputertechnologytoreducetheinterfacebetweenthecentralstationandthelocalstations.62.1CentralcontroltaskAcentralunitprovidesacentralizedpointtomonitorandcontrolthesystem7activities.Inthesystemtobedescribedthecentralcontrolunitservesafivefoldpurpose.(i)Itreceivesinformationfromthelocalstationsandoperatesthealarmsandotheroutputdevices.(ii)Itnotifiestheoperatorincaseofsystemmalfunction.(iii)Itprovidesanoverallsystemcontrolmanualandautomatic.(iu)Itprovidesasystemtestpointoflocalstationsanditself.(u)Itprovidesacentralpointforobservation,learningandadaptation.2.2LocalstationsThelocalstationscantakelocaldecisionsregardingrecognitionofarisksituation,andac