简介:Wirelesssensornetworkspromiseanewparadigmforgatheringdataviacollaborationamongsensorsspreadingoveralargegeometricalregion.Manyapplicationsimposedelayrequirementsfordatagatheringandaskfortime-efficientschedulesforaggregatingsenseddataandsendingtothedatasink.Inthispaper,theauthorsstudytheminimumdataaggregationtimeproblemundercollision-freetransmissionmodel.Ineachtimeround,datasentbyasensorreachesallsensorswithinitstransmissionrange,butasensorcanreceivedataonlywhenitistheonlydatathatreachesthesensor.Thegoalistofindthemethodthatschedulesdatatransmissionandaggregationatsensorssothatthetimeforallrequesteddatatobesenttothedatasinkisminimal.TheauthorsproposeanewapproximationalgorithmforthisNP-hardproblemwithguaranteedperformanceratio(7Δ)/(Iog_2|S|)+c,whichsignificantlyreducesthecurrentbestratioofΔ-1,whereSisthesetofsensorscontainingsourcedata,Δisthemaximalnumberofsensorswithinthetransmissionrangeofanysensor,andcisaconstant.Theauthorsalsoconductextensivesimulation,theobtainedresultsjustifytheimprovementofproposedalgorithmovertheexistingone.
简介:Asanadvancedprocessdetectiontechnology,electricalimpedancetomography(EIT)haswideapplicationprospectsandadvantagesinmedicalimagingdiagnosis.However,aseriesofissuesneedtobeaddressedbeforeapplyingEITforbedsidemonitoring.Medicaldiagnosisandbedsidemonitoringaredynamicmeasuringprocess,wherethepositionsofmeasuringelectrodesandtheshapeofthedetectedfieldarechangingdynamical.Duetotheinabilitytocopewiththechangeableelectrodepositionsandvariousdynamicfields,existingEITsystemsaremainlyusedforindustrialdetectioninconditionofstaticmeasurementandvisualization.Inthispaper,weinvestigatethedynamicmeasurementandvisualizationofhumanbreastinEITfield,describethedesignofthemeasuringsensorsystem,andexpoundthemeasuringprinciple.Themaincomponentofthehardwaresystemisabuiltinservoelectricalresistancetomographysensorwithcapacitiveslidingrod,whichcanadapttothecrowdofdifferentchestcontourandthechangeofchestshapeinthedynamicprocessofbreathing.Thecorrespondingmeasuringprincipleisextractingallreal-timepositionsofmeasuringelectrodes,thenobtainingthedynamicboundary,finallydividingthedetectionfieldrapidly.Experimentalresultsconfirmedthattheproposedsystemcanobtainreal-timelocationofboundarysensoranddynamicallysolvetheproblemofarbitrary-shapeboundarymeasurement.Theimagingresultsvalidatetheavailabilityofdesignedsensorsystemandtheeffectivenessofthecorrespondingmeasuringprinciple.
简介:Thispaperaddressestheproblemonsensorfaultestimationandfault-tolerantcontrolforaclassofTakagi-SugenoMarkovianjumpsystems,whicharesubjectedtosensorfaultsandpartiallyunknowntransitionrates.First,theoriginalplantisextendedtoadescriptorsystem,wheretheoriginalstatesandthesensorfaultsareassembledintothenewstatevector.Then,anovelreduced-orderobserverisdesignedfortheextendedsystemtosimultaneouslyestimatetheimmeasurablestatesandsensorfaults.Second,byusingtheestimatedstatesobtainedfromthedesignedobserver,astate-feedbackfault-tolerantcontrolstrategyisdevelopedtomaketheresultingclosed-loopcontrolsystemstochasticallystable.Basedonlinearmatrixinequalitytechnique,algorithmsarepresentedtocomputetheobservergainsandcontrolgains.Theeffectivenessoftheproposedobserverandcontrollerarevalidatedbyanumericalexampleandacomparedstudy,respectively,andthesimulationresultsrevealthattheproposedmethodcansuccessfullyestimatethesensorfaultsandguaranteethestochasticstabilityoftheresultingclosed-loopsystem.