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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.Thesystemusesmul
2、tiplesinglechiparchitectureattachedtoapartyline.Thecontrolalgorithmisbasedonatwo-levelhierarchyofdecisionmaking,thusthecomplexityisdistributed.Acompletecircuitdiagramisgivenforthelocalandthecentralstationwithrequirementsforthesoftwarestructure.Thedesigniskeptingeneralformsuchthatitcanbeadaptedtoamul
3、titudeofplantconfigurations.Itisparticularlyshownhownewdevelopmentsintechnology,especiallyCMOSsinglechipdevices,areincorporatedinthesystemdesigntoreducethecomplexityoftheoverallhardware,e.g.bydecomposingthesystemsuchthatlowerlevelsofhierarchyareabletohavesomeautonomyindecisionmaking,andthusamorecomp
4、lexdecisionissolvedinasimpledistributedmethod.1DetectionandalarmdevicesAbasicfiredetectionsystemconsistsoftwoparts,detectionandannunciation.Anautomaticdetectiondevice,suchasaheat,smokeorflamedetector,ultravioletorinfrareddetectorsorflameflicker,isbasedondetectingthebyproductofacombustion.Smokedetect
5、ors,ofbothionizationandopticaltypes,arethemostcommonlyuseddetectordevices.WhenatypicaldetectorofthistypeentersthealarmstateitscurrentconsumptionincreasesfromthepAtothemArange(say,fromamere15pAinthedormantmodeto60mA)intheactivemode.Inmanydetectorsthedetectoroutputvoltageiswelldefinedundervariousopera
6、tingconditions,suchasthoseTb1TmSldErVoMOUSS2giveninTableI.ThemoresensitivetheVoh9viDetectorcondition22vDtct(4inccutcondetector,themoresusceptibleitistofalsealarms.13V-22Vdtciorisorm1 V-13Vdetctorsman4armstat2 VdetcorsmShoftOfCUKC(MMMlonInordertocontrolthedetectorprecisely,eitherofthefollowingmethods
7、isused:acoincidencetechniquecanbebuiltintothedetector,orafilteringtechniquesuchthatalogiccircuitbecomesactiveonlyifxalarmsaredetectedwithinatimeperiodT.Thedetectiontechniquedependsgreatlyonthelocationandplantbeingprotected;smokedetectorsareusedforsleepingareas,infraredorultravioletradiationareusedwh
8、enflammableliquidsarebeinghandled,heatdetectorsareusedforfiresuppressionorextinguishingsystems.Ingeneral,lifeandpropertyprotectionhavedifferentapproaches.Alarmdevices,apartfromtheusualaudibleorvisiblealarms,mayincorporatesolidstatesoundreproductionandemergencyvoicecommunicationorprintersthatrecordti
9、me,date,locationandotherinformationrequiredbythestandardcodeofpracticeforfireprotectionforcomplexplants.Heaviside4hasanexcellentreviewofalltypesofdetectorsandextinguishersystems.2.1 ControlphilosophyanddivisionoflabourOurcontrolphilosophyisimplementedhierarchically.Threelevelsofsystemhierarchyareimp
10、lemented,withtwolevelsofdecisionmaking.Thereisnocommunicationbetweenequipmentonthesamelevel.Interactionbetweenlevelsoccursbyupwardstransferofinformationregardingthestatusofthesubsystemsanddownwardstransferofcommands.ThisisshowninFig.1whereatlevel1isthecentralstationmicrocomputerandistheultimatedecis
11、ionmaker(whennotinmanualmode).Atlevel2arethelocalcontrollers,whichresideinthelocalstations.Atlevel3aretheactualdetectorsandactuators.Amanualmodeofoperationisprovidedatalllevels.Informationregardingthestatusofalldetectorsistransmittedonaperareabasistothelocalcontrollers.Theirinformationiscondensedand
12、transmittedupwardtothecentralmicrocomputer.Transferofstatusisalwaysunidirectionalandupwards.Transferofcommandsisalwaysunidirectionalanddownwards,withexpansionatthelocalcontrollevel.Thisapproachpreservesthestrictrulesofthehierarchyforexactmonitoringdetectionandalarmsystemsassociatedwithhighriskplants
13、.SCFel Court4 philmoy2/ PItOCEEDINGS. Vol. 135. Pt. C, Nd I. FEVA Y /MTheclassificationofthetwolayersofcontrolsisbaseduponlayersofdecisionmaking,withrespecttothefactsthat(a) Whenthedecisiontimecomes,themakingandimplementationofadecisioncannotbepostponed(b) Thedecisionshaveuncertainty(c) Itwillisolat
14、elocaldecisions(e.g.locallyWemighthaveanalarmalthoughtheremaybeafaultwiththesystem)3 GeneralhardwareI:Fig.2depictsourdesigninthesimplestofforms.Thesystemusesanopenpartylineapproachwithfourconductorcablesgoinginaloopsharedbyalltheremotedevicesandthecontrolpanel.Thisapproachissimpleinconceptandisecono
15、micallyfeasible.However,onemajordisadvantageisthedependencyonasinglecableforpowerandsignaling.Incaseswherereliabilityisofextremeimportance,twooreventhreecablestakingdifferentroutesthroughoutthesystemmaybeconnectedinparallel.Fig.3givesthedrivercircuitryrequiredtoderiveanexpandablebus.Thisdesigntakesa
16、dvantageofrecentadvancesinthesinglechipmicrocomputertechnologytoreducetheinterfacebetweenthecentralstationandthelocalstations.FROMINPUT TO OUTPUT2.IEEPROCEEDINGS, Vol. 135, Pi.A central unit provides a centralized point to monitor andFig.4 Aznwff rrurt dttfrmtooutput (Xye ftP 3 ORTADCooeS0V HfF IgtoOEr 321AEMHCHAooe 5tooct 42UC