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:光纤通信不仅可以应用在通信的主干线路中,还可以应用在电力通信控制系统中,进行工业监测、控制,而且在军事领域的用途也越来越为广泛。本文探讨了光纤通信技术的主要特征及应用。