电容层析成像（ECT）传感器检测土壤水分【中文6600字】
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- 关 键 词：
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电容
层析
成像
ect
传感器
检测
土壤
水分
水份
中文
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电容层析成像（ECT）传感器检测土壤水分【中文6600字】,电容,层析,成像,ect,传感器,检测,土壤,水分,水份,中文
- 内容简介：
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SOILMOISTUREDETECTIONUSINGELECTRICALCAPACITANCETOMOGRAPHYECTSENSORNURZHARINABINTIABDKARIMELECTRICALANDELECTRONICSENGINEERINGDEPARTMENTUNIVERSITITEKNOLOGIPETRONAS31750TRONOH,PERAKDARULRIDZUAN,MALAYSIAZHARINABDKARIMGMAILCOMIDRISBINISMAILELECTRICALANDELECTRONICSENGINEERINGDEPARTMENTUNIVERSITITEKNOLOGIPETRONAS31750TRONOH,PERAKDARULRIDZUAN,MALAYSIAIDRISIMPETRONASCOMMYABSTRACTTHISPAPERBRIEFLYDISCUSSESTHEMEASUREMENTONSOILMOISTUREDISTRIBUTIONUSINGELECTRICALCAPACITANCETOMOGRAPHYECTTECHNIQUEECTSENSORWITH12ELECTRODESWASUSEDFORVISUALIZATIONMEASUREMENTOFPERMITTIVITYDISTRIBUTIONECTSENSORWASCALIBRATEDUSINGLOWANDHIGHPERMITTIVITYMATERIALIEDRYSANDANDSATURATEDSOILSSANDANDCLAYRESPECTIVELYTHEMEASUREMENTSOBTAINEDWERERECORDEDANDFURTHERANALYZEDBYUSINGLINEARBACKPROJECTIONLBPIMAGERECONSTRUCTIONPRELIMINARYRESULTSHOWSTHATTHEREISAPOSITIVECORRELATIONWITHINCREASINGWATERVOLUMEKEYWORDSSOILMOISTUREDISTRIBUTIONECTSENSORDIELECTRICCONSTANTVOLUMETRICWATERCONTENTIINTRODUCTIONESTIMATIONOFSOILMOISTURECONTENTISIMPORTANTINAGRICULTUREESPECIALLYDURINGIRRIGATIONSCHEDULINGCHANGESINTHEPERCENTAGEOFSOILMOISTUREDURINGTHEIRRIGATIONEVENTCANBECONTROLLEDBYINDICATINGTHEAMOUNTOFAPPLIEDWATERTOSOILCONTINUOUSMONITORINGOFSOILMOISTURECONTENTWITHINANDBELOWTHEROOTINGZONECANFACILITATEOPTIMALIRRIGATIONSCHEDULINGAIMEDATMINIMIZINGBOTHTHEEFFECTSOFWATERSTRESSONTHEPLANTS,ANDALSOLEACHINGOFWATERBELOWTHEROOTZONEWHICHCANHAVEADVERSEENVIRONMENTALEFFECTS1INTHISEXPERIMENTALWORK,ECTISUSEDTOMEASURESOILMOISTURECONTENTBASEDONTHEIMAGEOFMOISTUREDISTRIBUTIONINSOILTHESOILMOISTUREMEASUREMENTISBASEDONTHECONCEPTOFTHEDIELECTRICCONSTANTINADRYMATERIALCONSISTINGSOILPARTICLESANDAIRISRELATIVELYSMALL15TO4WHEREASTHEDIELECTRICWATERCONSTANTISLARGER80ATROOMTEMPERATURE15THESMALLAMOUNTSOFWATERINSOILCAUSETHEDIELECTRICCONSTANTOFTHERESULTANTSOILWATERAIRMIXTURETOEXHIBITACOMPOSITEDIELECTRICCONSTANTTHATCANBERELATEDTOTHESOILMOISTURECONTENTTHROUGHASIMPLECALIBRATIONPROCEDURE15TIMEDOMAINREFLECTOMETRYTDRMETHOD,FREQUENCYDOMAINREFLECTOMETRYFDRMETHOD,AMPLITUDEDOMAINREFLECTOMETRYADRMETHODANDCAPACITIVEMETHODARETHECURRENTMETHODSAVAILABLEFORTHEELECTRICALMEASUREMENTSOFTHEDIELECTRICCONSTANT12EGTDRINSTRUMENTSUSEMEASUREDPULSETRAVELTIMESTODETERMINETHEAPPARENTSOILDIELECTRICPERMITTIVITY14SOMEOFTHERESEARCHERSFOUNDTHATTHECAPACITANCEPROBEMETHODWASINDEPENDENTOFSOILTYPEWITHINWIDERANGESOFSOILMOISTURELEVELS2HOWEVER,THESEMETHODSDONOTDETERMINETHEIMAGEDISTRIBUTIONOFTHEMOISTUREINTHESOILINECT,THEIMAGEDISTRIBUTIONOFPERMITTIVITYMATERIALCANBESEENINTHEFORMOFIMAGEPIXELDEPENDINGONTHESCALEOFTHEPERMITTIVITYMATERIALFROMLOWESTTOHIGHESTVALUEECTHASBEENDEVELOPEDSINCE1980SFORVISUALIZATIONANDMEASUREMENTOFAPERMITTIVITYDISTRIBUTIONINCROSSSECTIONUSINGAMULTIELECTRODECAPACITANCESENSOR21THEECTSENSORMEASURESTHEDISTRIBUTIONOFPERMITTIVITYOFTHESOILMOISTUREINSIDETHEINSULATINGFRAMEANDCAPTURESTHEIMAGEDISTRIBUTIONANDMEASUREMENTDATAIISOILMOISTURESOILMOISTURECONTENTIMPACTSCROPGROWTHDIRECTLYANDALSOINFLUENCESTHEFATEOFAGRICULTURECHEMICALSAPPLIEDTOSOIL20ONEOFTHEKEYCOMPONENTSINMANAGINGIRRIGATIONSCHEDULINGISBYDETERMININGTHEMOISTURECONTENTINSOILZAZUETAANDXIN1994REPORTEDTHATSOILMOISTURECONTENTMAYBEDETERMINEDVIAITSEFFECTONDIELECTRICCONSTANTBYMEASURINGTHECAPACITANCEBETWEENELECTRODEPAIRSIMPLANTEDINTHESOIL7OTHERTHANTHAT,THESOILPHYSICALCONDITIONPLAYSANIMPORTANTROLEINSOILMOISTUREDETERMINATIONINNORMALSOILCONDITION,AIRANDWATERAREFILLEDINTHEPORESPACESOFSOIL,THUSTHEDIELECTRICCONSTANTOFTHESOILWATERAIRMIXTURECANBEMEASUREDTHEDIELECTRICCONSTANTFORAIRIS1WHILEDIELECTRICCONSTANTOFWATERIS80ROOMTEMPERATUREWHENVOLUMEOFWATERCONTENTINTHEPORESPACESINCREASES,THEDIELECTRICCONSTANTOFTHESOILWILLINCREASEFIG1SHOWSTHATTHEUNSATURATEDSOILISCOMPOSEDOFSOLIDPARTICLES,ORGANICMATERIALSANDPORES4THEPORESPACESOFTHESOILCONTAINAIR,WATERANDROOTROOTSOILPARTICLEWATERAIRFIGURE1ILLUSTRATIONOFSOILPHYSICALCONTAINSSOILPARTICLES,WATER,AIRANDPLANTSROOT49781612848969/11/26002011IEEENTHETERMINOLOGYOFMOISTURECONTENTSTATEDINASTMD464308ISTHERATIO,EXPRESSEDASPERCENTAGE,OFTHEMASSOF“PORE”OR“FREE”WATERINAGIVENMASSOFSOILTOTHEMASSOFTHESOLIDPARTICLES19THEMOISTURECONTENTINSOILCANBEANALYZEDBYKNOWINGTHESOILPHYSICALCONDITIONSOFTHESOILTHESOILSBULKDENSITY,DBISWEIGHTOFDRYSOILTOTHEUNITVOLUMESOLIDSANDPOREPARTICLEDENSITY,DPINVOLVESMEASURINGTHEWEIGHTOFDRYSOILANDTHEVOLUMETRICSOILPARTICLEIEONLYSOLIDANDNOPORESPACEFROMBOTHBULKDENSITYANDPARTICLEDENSITYVALUES,THESOILPOROSITYCANBECALCULATEDBYUSINGEQUATION1617AECTSENSORTHEREARESEVERALCOMPONENTSNEEDTOBECONSIDEREDINDESIGNINGECTSENSORECTSENSORCONSISTSOFFOURMAINPARTS21MEASUREMENTELECTRODESOUTER,AXIALENDANDRADIALSCREENSANINSULATINGFRAMECOAXIALCABLESANDCONNECTORSSOILPOROSITY1DBDP1THEBASICMETHODISTOSURROUNDTHEVESSELORINSULATINGFRAMEWITHASETOFELECTRODESMETALPLATESANDTHECAPACITANCEMEASUREMENTSISMEASUREDBETWEENEACHUNIQUEMOISTURECONTENT,MDETERMINESTHEAMOUNTOFWATERWITHAGIVENMASSOFSOILMOISTURECONTENTISCALCULATEDBYDIVIDINGTHEWEIGHTOFWATERINTHESOILBYTHEWEIGHTOFDRYSOILTHEEXPRESSIONOFWATERCONTENTINTERMSOFVOLUMEOFWATERPERVOLUMEOFSOILCANBEDETERMINEDASVOLUMETRICWATERCONTENT,VUSINGEQUATION2617PAIROFELECTRODESTYPICALLY,MEASUREMENTELECT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RVOLUMETRICWATERCONTENTFORMOSTSOILISEXPRESSEDINREFRACTIVEINDEXMODELASINEQUATION81420FORECTSENSORUSING12ELECTRODESANDTRANSDUCERBASEDMULTIPROCESSORSYSTEM3WITHLBP,THEPERMITTIVITYDISTRIBUTIONINECTCANBEDETERMINEDTHERELATIONSHIPCANBEVAB8SEENINLINEARNORMALIZEDFORMASINEQUATION511CSG5THECOEFFICIENTSVALUEFORAANDBPARAMETERFALLWITHINTHERANGEINTDRCALIBRATIONSANDTHEMEANVALUESOFA0110ANDB018014THEREFRACTIVEINDEXMODELISOBTAINEDBYMINIMIZINGTHESUMOFSQUAREDDIFFERENCESBETWEENTHEPREDICTEDPERMITTIVITYANDTHEPERMITTIVITYACCORDINGTOEQUATION820THEREFRACTIVEINDEXMODELISABASELINEWHERECISTHENORMALIZEDCAPACITANCEMATRIX,SISTHETRANSDUCERSENSITIVITYMATRIXWHICHCONTAINSTHESETOFSENSITIVITYMATRICESFOREACHELECTRODEPAIRS,ANDGREPRESENTSTHENORMALIZEDPERMITTIVITYTHEPRODUCTOFGISMULTIPLICATIONOFTHETRANSPOSEOFTHETRANSDUCERSENSITIVITYMATRIXWITHTHENORMALIZEDCAPACITANCEMATRIXEQUATIONDEVELOPEDASAREFERENCEFORCOMPARINGDIFFERENTINDIVIDUALSOILCALIBRATIONS14FORTOPPETAL1980EMPIRICALEQUATIONANDREFRACTIVEINDEXMODELEQUATION,ONLYTHEREALCOMPONENTOFPERMITTIVITYISCONSIDEREDSOILBULKDENSITYANDMOISTURECONTENTAREUSEDTOCALCULATEVOLUMETRICWATERCONTENTVALUEVIEXPERIMENTALDESCRIPTIONSTHERELATIONSHIPBETWEENAPPARENTSOILPERMITTIVITYANDVOLUMETRICWATERCONTENTHASBEENSUBJECTOFMUCHRESEARCHINTHELAST30YEARS5THEEXPERIMENTALWORKHASBEENCONDUCTEDINTHELABORATORYBYUSINGECTSYSTEMASTHETESTAPPARATUSECTSENSORISCONNECTEDTOTHEDATAACQUISITIONUNITBYUSINGCONNECTORSTHATCONNECTTOTHEELECTRODESINECTSENSORVIACOAXIALCABLESFOR1TO12ELECTRODESACCORDINGTOTHEPLANEARRANGEMENTONTHEDEVICETHECALIBRATIONPROCEDURESTARTSWITHTHECALIBRATIONOFLOWERPERMITTIVITYMATERIALIEDRYSOILANDCONTINUEDWITHHIGHERPERMITTIVITYMATERIALIESATURATEDSOILTHISCALIBRATIONISIMPORTANTINORDERTOMEASURETHENORMALIZEDCAPACITANCEVALUE,CNASIN3CALIBRATIONISALSOUSEDASLOWESTANDHIGHESTSETPOINTVALUESFORONLINEMEASUREMENTDATATHEONLINEMEASUREMENTISCONDUCTEDAFTERTHECALIBRATIONMEASUREMENTHASBEENPERFORMEDECTSENSORISFILLEDWITHDRYSOILIESANDORCLAYFILLEDINSIDETHEINSULATINGFRAMEASILLUSTRATEDINFIG3ANAMOUNTOFWATERISADDEDINTOTHESOILINTHEECTSENSOR,IE10ML,20ML,AND400MLACCORDINGLYTHEDATAISCAPTUREDFORTIMEINTERVALOF10SECONDSTHESAMEPROCEDUREISREPEATEDFORTHESEVERALTIMESFORDATACOMPARISONANDANALYSISFROMSOILMOISTUREDISTRIBUTIONIMAGEINECT,THEPERCENTAGEOFTHESOILMOISTUREINTHEIMAGEPIXELISCALCULATEDBYREFERRINGTOTHECOLORSCALEOFFROM“0”TO“1”THEMOISTUREPERCENTAGEANDBULKDENSITYISUSEDTOCALCULATETHEVOLUMETRICWATERCONTENT,VOFTHETESTSOILOTHERTHANTHAT,OVENDRYINGMETHODISASTANDARDTESTMETHODTODETERMINETHESOILMOISTURECONTENTTHEOVENDRYINGTECHNIQUEISPROBABLYTHEMOSTWIDELYUSEDOFALLGRAVIMETRICMETHODSFORMEASURINGSOILMOISTURE7MICROWAVEHEATINGISAPROCESSBYWHICHHEATISINDUCEDWITHINAMATERIALDUETOTHEINTERACTIONBETWEENDIPOLARMOLECULESOFTHEMATERIALANDANALTERNATING,HIGHFREQUENCYELECTRICFIELD19INOVENDRYINGMETHOD,ASAMPLEOFSOILISDRIEDINTHEMICROWAVEOVENFOR24HOURSWITH105OCTEMPERATUREINORDERISTOENSURETHATTHEREISNOMOISTURECONTENTEXISTSINTHESAMPLESOILTHEWEIGHTOFDRYSOILISMEASUREDASWELLASTHEWEIGHTOFWETSOILACCORDINGTOASTMD464308,THEWATERCONTENTOFSOILCANBECALCULATEDASEQUATION9AND1019VIIRESULTSAECTCALIBRATIONMEASUREMENTTHETOMOGRAMIMAGEHASITSUNIQUECOLORSCALEIEBLUETHATINDICATES“0”LOWPERMITTIVITYMATERIALANDREDINDICATES“1”HIGHPERMITTIVITYMATERIALINBETWEENBLUETOREDTHEREAREOTHERCOLORSINDICATINGDIFFERENTSCALEFROM0001TO0999APPROXIMATELYFIG3SHOWSLOWERCALIBRATIONUSINGDRYSANDANDSATURATEDSANDFORHIGHCALIBRATIONWHILEFIG4SHOWSTHEIMAGEOFTHECALIBRATIONSLOWCALIBRATIONDRYSANDHIGHCALIBRATIONSATURATEDSANDFIGURE3LOWANDHIGHCALIBRATIONFORSAND01FIGURE4LOWANDHIGHCALIBRATIONIMAGESBECTONLINEMEASUREMENTINONLINEMEASUREMENT,THESOILMOISTUREDISTRIBUTIONFORDIFFERENTVOLUMEOFWATERCONTENTINSOILCANBEVERIFIEDINTABLEITHETYPESOFSOILSUSEDINTHISMEASUREMENTARESANDWMASSOFWATERMASSOFOVENDRIEDSOILX1009ANDCLAYINTHISIMAGEDISTRIBUTION,THECOLORSCALESHOWSTHAT,THESENSITIVITYOFTHEELECTRODESINECTSENSORDEPENDSUPONTHEVOLUMEOFWATERANDAIRINTHESOILASTHEVOLUMEOFWATERADDEDINCREASES,THEMOISTUREPERCENTAGEINCREASESANDTHECOLORSCALEMOVESTOWARDS“1”ORREDCOLORTHATINDICATESWM1M2X100M2MC10HIGHERPERMITTIVITYVALUEOFTHETESTSOILSITSHOWSTHATTHESOILREACHESITSSATURATIONVALUEWHENTHEPORESPACESOFTHESOILAREFULLYFILLEDWITHWATERCONTENTFROMTHEIMAGESSHOWNINWHEREWCANBEDENOTEDASMIETHEMOISTURECONTENT,MCISTHEMASSOFCONTAINERG,M1ISTHEMASSOFCONTAINERANDWETSOILG,ANDM2ISTHEMASSOFCONTAINERANDDRYSOILGFROM9AND10,THEMOISTURECONTENTVALUEISSUBSTITUTEDINTO2TOCALCULATETHEVOLUMETRICWATERCONTENT,VBYKNOWINGTHESOILBULKDENSITYTHEVOLUMETRICWATERCONTENTFROMONLINEMEASUREMENTINECTANDOVENDRYINGMETHODSCANBESUBSTITUTEDINTOEMPIRICALEQUATIONSTOCALCULATETHEDIELECTRICCONSTANTMEASUREMENTTABLEI,ITCANBESEENTHATTHEMOISTUREDISTRIBUTIONSINSANDAREEVENLYDISTRIBUTEDTHANCLAYTHISISDUETOTHESOILPROPERTIESITSELFWHERETHESANDHASLARGERSOILPARTICLESANDPORESPACESTHATALLOWSTHEWATERTOFLOWTHROUGHITEASILYMEANWHILE,INCLAY,THEWATERISHARDLYDISTRIBUTEDWHENTHEVOLUMEOFCLAYISLARGERTHANVOLUMEOFWATERAMIXTUREOFHIGHERVOLUMEOFCLAYANDSMALLERAMOUNTVOLUMEOFWATERRESULTSINAMIXTURETHATCANBESHAPEDTABLEIIMAGEOFSOILMOISTUREDISTRIBUTIONINECTECTIMAGEDISTRIBUTIONPERCENTAGEOFMOISTUREDISTRIBUTIONINECTIMAGEPIXELWATERVOLUMEMLSANDCLAYSANDCLAY000801809170316036223343240568851503207813726540097309102FROMTHEECTIMAGEDISTRIBUTIONINTABLEI,WHEN80MLWATERISADDEDINTODRYSAND,THEPERCENTAGEOFMOISTUREDISTRIBUTIONOBTAINEDIS1809BYCALCULATINGTHECOLORSCALERATIOINTHEECTIMAGEPIXELTHECHANGESINCOLORSCALEINDICATESANEXISTENCEOFWATERCONTENTINTHATPARTICULARAREATHECOLORSCALETURNSTOREDWHENTHEPERCENTAGEOFMOISTUREINTHESAND5688IEWITH240MLWATERISADDEDTHISRESULTSHOWSTHATTHEPERCENTAGEOFMOISTUREINCREASESASTHEVOLUMEOFWATERADDEDINTHESANDINCREASESTHESATURATIONLEVELISINDICATEDWHENTHEPORESPACESINTHESANDISFULLYFILLEDWITHWATERFORTHEIMAGEOFMOISTUREDISTRIBUTIONINCLAY,THEPERCENTAGEOFMOISTUREISLOWERTHANSANDTHECLAYREACHESITSSATURATIONLEVELLATERTHANSANDINTHISCASE,WHEN400MLOFWATERISADDEDINTHECLAY,THEIMAGEDISTRIBUTIONSHOWSTHATTHECLAYHASNOTREACHITSSATURATIONLEVELFIGURE5DIELECTRICCONSTANTVERSUSVOLUMETRICWATERCONTENTGRAPHFORSANDFIGURE6DIELECTRICCONSTANTVERSUSVOLUMETRICWATERCONTENTGRAPHFORCLAYTHERELATIONSHIPSBETWEENDIELECTRICCONSTANTANDVOLUMETRICWATERCONTENTOFTHETESTSOILSIESANDANDCLAYCANBESEENINFIG5AND6THEDIELECTRICCONSTANTINCREASESWITHINCREASINGINVOLUMETRICWATERCONTENTITISANALYZEDBYUSINGEMPIRICALEQUATIONS,OVENDRYINGMETHOD,ANDECTSENSORONLINEMEASUREMENTDATAFROMFIG5AND6,THEONLINEMEASUREMENTDATAISPLOTTEDBYEMPIRICALMODELEQUATIONSTHEONLINEMEASUREMENTDATASHOWSAPOSITIVEINCREMENTINPERCENTAGEOFMOISTURECONTENTWITHRESPECTTOTHEDIELECTRICCONSTANTTHEDIELECTRICCONSTANTSINSANDANDCLAYHAVEACLOSERELATIONSHIPWITHEXISTENCEOFWATERCONTENTINSOILWHENTHEWATERCONTENTFILLSINTHEPORESPACES,ITREDUCESTHEVOLUMEOFAIRANDINCREASESTHEVOLUMEOFWATERINSOILTABLEIIPERCENTAGEOFDIFFERENCEINOVENDRYANDECTTABLEIISHOWSTHATTHEREISSOMEERROROCCURSINPERCENTAGEMOISTUREDISTRIBUTIONINECTONLINEMEASUREMENTSFORSANDANDCLAYINOVENDRYING,THEWEIGHTOFDRYSOILISANDTHEWEIGHTOFTHEWETSOILISMEASUREDTHEPERCENTAGEOFMOISTUREISCALCULATEDUSING10FORTHISMETHODINECTONLINEMEASUREMENT,THESAMEAMOUNTOFWATERISADDEDINTOTHESOILANDTHEIMAGEOFMOISTUREDISTRIBUTIONISCAPTUREDBYCALCULATINGTHECOLORSCALEINTHEIMAGEDISTRIBUTION,THEPERCENTAGEOFMOISTUREISOBTAINEDFROMBOTHMETHODS,THEPERCENTAGEDIFFERENCEISCALCULATEDBYUSINGOVENDRYINGDATAASTHETRUEVALUESINCEITISASTANDARDTESTINGMETHODINDETERMININGTHEPERCENTAGEOFMOISTUREINSOILANDECTONLINEMEASUREMENTDATAASTHEMEASUREDVALUEEGWHEN80MLISADDEDINSAND,20MOISTURECONTENTISOBTAINEDBYCALCULATINGTHEMOISTUREPERCENTAGEINECTONLINEMEASUREMENT,WHEN80MLWATERISADDEDINTHESOIL,THEMOISTUREPERCENTAGEIS1809WHICHISCALCULATEDUSINGTHECOLORSCALEINTHEIMAGEPIXELTHEPERCENTAGEOFDIFFERENCEISCALCULATEDUSINGTHEMOISTUREPERCENTAGEVALUESFROMBOTHMETHODSTHEERROROCCURSCANBEREDUCEDBYIMPROVINGTHECALIBRATIONMEASUREMENTANDEXPERIMENTALPROCEDURESVIIICONCLUSIONANDFUTUREWORKINTHECONCLUSION,MONITORINGSOILMOISTUREDISTRIBUTIONISIMPORTANTINAGRICULTURETOENSURETHEPLANTGROWTHTHISEXPERIMENTALWORKHASMEASUREDTHESOILMOISTUREDISTRIBUTIONBYUSING12ELECTRODESECTSENSORTHEIMAGEOFSOILMOISTUREDISTRIBUTIONINECTINCREASINGFROMCOLORSCALE“0”TO“1”IEFROMLOWERTOHIGHERP
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