外文翻译---脉冲输出型数字涡街流量计的研究

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1、附录AResearchonpulseoutputmodeldigitalvortexflowmetersThevortexflowmeteriswidelyusedindifferentfieldsduetoitsflexibilitytovariousmedia,non-mobileparts,simplestructureandlonglifeetc.However,ithaspoorperformancewhenoperatingatlowflowratewheretheSignal-to-Noiseratioisvery

2、smalloreventhesignalissubmergedbythenoise.Thetraditionalanalogvortexflowmeterhasbenefitsofsteadysignal,highaccuracyandgoodrealtimeintheregularflowrange,whileitalsohasadisadvantageofweaksignaldifficulttodetectatlowflowrate,whichleadstounsatisfyinglowerlimitandasmaller

3、rangeratioof10:1.Basedonthepreviouseffortsapulseoutputmodeldigitalvortexflowmeterisdevelopedsuccessfully,whichinheritstheadvantagesoftheanalogoneandmakeupitsshortagementionedabove.Thedigitalvortexflowmeterwithitsdouble-corestructurethatmeansacoupleofCPUsmadeupofDSPan

4、dMSP430identifiesthevortexsignalsfromnoisesbythefrequencyspectrumanalyzingalgorithminDSPatlowflowratewheretheanalogoneisnotaccurate,orevencan’twork.MeanwhileitworksoutbyitsmicrocontrollerMSP430thefrequencyofthevortexsignalthatissquarewavesoutputfrompre-amplifierforth

5、evortexsignalsintheregularflowrangewheretheSignal-to-Noiseratioisn’ttoomuchsmallandtheanalogoneisaccurateandrealtime.Thisdissertationconsistsoftheory,hardware/softwaredesignandexperiment.Themainpointincludes:1.Theschemecalleddouble-channelworkmodelofthepulseoutputmod

6、eldigitalvortexflowmeterisdesigned.Theprincipleisaswitchoftwodifferentmethodstodetectthevortexsignal.Thatisusingspectrumanalysisofdigitalsignalatlowflowrateandfrequencycountinglikeanalogvortexflowmetersintheregularflowrange.Thecriticalcriterionoftheswitchpointistheun

7、certaintyofthefrequency.2.Apulseoutputmodeldigitalvortexflowmeterisdevelopedsuccessfully.TheflowmeterisstudiedrespectivelyatDN25andDN50pipelinesofthewaterflowexperimentfacilityandDN50andDN100pipelinesofthegasflowexperimentfacilitythatlocateatProcessDetect&ControlLabo

8、ratoryinTianjinUniversity.Andthedatashowsthatthedigitalflowmeterhasthepropertyofabetterlowerlimitthantheanalogoneandabiggerrangerat