外文翻译 zigbee检测探头在冷藏蔬菜运输现实条件下的测试大学论文Word文件下载.docx
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10128
学号:
本科毕业设计
外文文献及翻译
(
英文题目:
TestingZigBeeMotesforMonitoringRefrigeratedVegetableTransportationunderRealConditions
中文题目:
ZigBee检测探头在冷藏蔬菜运输现实条件下的测试
学生姓名:
学院:
信息工程学院
系别:
电子信息工程
专业:
班级:
指导教师:
教授
二〇一年月
Abstract
Qualitycontrolandmonitoringofperishablegoodsduringtransportationanddeliveryservicesisanincreasingconcernforproducers,suppliers,transportdecisionmakersandconsumers.Themajorchallengeistoensureacontinuous„coldchain‟fromproducertoconsumerinordertoguarantyprimeconditionofgoods.Inthisframework,thesuitabilityofZigBeeprotocolformonitoringrefrigeratedtransportationhasbeenproposedbyseveralauthors.However,uptodatetherewasnotanyexperimentalworkperformedunderrealconditions.Thus,themainobjectiveofourexperimentwastotestwirelesssensormotesbasedintheZigBee/IEEE802.15.4protocolduringarealshipment.Theexperimentwasconductedinarefrigeratedtrucktravelingthroughtwocountries(SpainandFrance)whichmeansajourneyof1,051kilometers.Thepaperillustratesthegreatpotentialofthistypeofmotes,providinginformationaboutseveralparameterssuchastemperature,relativehumidity,dooropeningsandtruckstops.Psychrometricchartshavealsobeendevelopedforimprovingtheknowledgeaboutwaterlossandcondensationontheproductduringshipments.
1.Introduction
Perishablefoodproductssuchasvegetables,fruit,meatorfishrequirerefrigeratedtransportation.Foralltheseproducts,Temperature(T)isthemostimportantfactorforextendingshelflife,beingessentialtoensurethattemperaturesalongthecoldchainareadequate.However,localtemperaturedeviationscanbepresentinalmostanytransportsituation.Reportsfromtheliteratureindicategradientsof5°
Cormore,whendeviationsofonlyafewdegreescanleadtospoiledgoodsandthousandsofEurosindamages.Arecentstudyshowsthatrefrigeratedshipmentsriseabovetheoptimumtemperaturein30%oftripsfromthesuppliertothedistributioncentre,andin15%oftripsfromthedistributioncentretothestores.Royetal.analyzedthesupplyoffreshtomatoinJapanandquantifiedproductlossesof5%duringtransportationanddistribution.Thermalvariationsduringtransoceanicshipmentshavealsobeenstudied.Theresultsshowedthattherewasasignificanttemperaturevariabilitybothspatiallyacrossthewidthofthecontaineraswellastemporallyalongthetrip,andthatitwasoutofthespecificationmorethan30%ofthetime.Inthoseexperimentsmonitoringwasachievedbymeansoftheinstallationofhundredsofwiredsensorsinasinglecontainer,whichmakesthissystemarchitecturecommerciallyunfeasible.
Transportisoftendonebyrefrigeratedroadvehiclesandcontainersequippedwithembeddedcoolingsystems.Insuchenvironments,temperaturesriseveryquicklyifareeferunitfails.Commercialsystemsarepresentlyavailableformonitoringcontainersandtrucks,buttheydonotgivecompleteinformationaboutthecargo,becausetheytypicallymeasureonlytemperatureandatjustonepoint.
Apartfromtemperature,waterlossisoneofthemaincausesofdeteriorationthatreducesthemarketabilityofperishablefoodproducts.Transpirationisthelossofmoisturefromlivingtissues.Mostweightlossofstoredfruitiscausedbythisprocess.Relativehumidity(RH),Toftheproduct,Tofthesurroundingatmosphere,andairvelocityallaffecttheamountofwaterlostinfoodcommodities.Freewaterorcondensationisalsoaproblemasitencouragesmicrobialinfectionandgrowth,anditcanalsoreducethestrengthofpackagingmaterials.
Partiesinvolvedneedbetterqualityassurancemethodstosatisfycustomerdemandsandtocreateacompetitivepointofdifference.Successfultransportinfoodlogisticscallsforautomatedandefficientmonitoringandcontrolofshipments.Thechallengeistoensureacontinuous„coldchain‟fromproducertoconsumerinordertoguarantyprimeconditionofgoods.
TheuseofwirelesssensorsinrefrigeratedvehicleswasproposedbyQingshanetal.asanewwayofmonitoring.SpecializedWSN(WirelessSensorNetwork)monitoringdevicespromisetorevolutionizetheshippingandhandlingofawiderangeofperishableproductsgivingsuppliersanddistributorscontinuousandaccuratereadingsthroughoutthedistributionprocess.Inthisframework,ZigBeewasdevelopedasaverypromisingWSNprotocolduetoitslowenergyconsumptionandadvancednetworkcapabilities.Itspotentialformonitoringthecoldchainhasbeenaddressedbyseveralauthorsbutwithoutrealexperimentation,onlytheoreticalapproaches.Forthisreason,inourworkrealexperimentationwiththeaimofexploringthelimitsofthistechnologywasapriority.
Themainobjectiveofthisproj