简介:Oneofthemaindriversforintelligenttransportationsystemsissafety.Adaptivecruisecontrol,asacommonsolutionfortrafficsafety,hasextendedfromradarstocameras.Duetohighmobilityofvehiclesandunevennessofroads,thepicturequalityofcamerashasbeengreatchallengesforcamera-basedadaptivecruisecontrol.Inthispaper,animagedistortioncorrectionalgorithmisaddressed.Ourmethodisbasedonopticalflowtechnologywhichisnormallyappliedinmotionestimationandvideocompressionresearch.Wearethefirsttoattempttoadaptitinimagedistortioncorrection.Twoopticalflowapproaches,theLucas-KanademethodandtheHorn-Schunckmethod,areselectedandcompared.Theprocedureofimagedistortioncorrectionusingtheopticalflowmethodhasbeentestedbybothsynthetictestimagesandcameraimages.TheexperimentalresultsshowthattheLucas-Kanademethodismoresuitableinthecorrectionofimagedistortion.
简介:Inordertofindtherelationshipsbetweenthedistortionruleoftheconcreteanditssurroundingstressfield,areal-timeopticalholographicsetupisusedtorecordthedistributionandthevariationofthesamples,thewaveformsofultrasonicemissionstimulatedbythemicro-cracksarerecordedbyatransientautomaicwaveformrecorderthdeterminethetime,locationandintensityoftheactionsofmicro-cracks,Theexperimentresultsareworthystudying.Thismethodprovidesausefulexperimentalapproachtostudythebrittlenessmaterials.
简介:Asoneofthenextgenerationimagingspectrometers,theinterferentialspectrometer(IS)possessestheadvantagesofhighthroughput,multi-channelandgreatresolution.ThedataofISareproducedinthespatialdomain,butopticalapplicationsareintheFourierdomain.TraditionalcompressionmethodscanonlyprotectthevisualqualityofinterferometerdatainthespatialdomainbutignorethedistortionintheFourierdomain.TherelationbetweenthedistortionintheFourierdomainandthecompressioninthespatialdomainisanalyzed.Bymathematicalproofandvalidationwithexperiments,therelationbetweenspatialandFourierdomainsisdiscovered,andthesignificanceintheFourierdomainismoreimportantasopticalpathdifference(OPD)increasinginthespatialdomain.Basedonthisrelation,anovelcodingschemeisproposed,whichcancompressdatainthespatialdomainwhilereducingthedistortionintheFourierdomain.Inthisscheme,thebitstreamofthesetpartitioninginhierarchicaltrees(SPIHT)istruncatedbyadaptivelyliftingrate-distortionslopesaccordingtotheprioritiesofOPDbasedonrate-distortionoptimizationtheory.ExperimentalresultsshowthattheproposedmethodcanprovidebetterprotectionofspectrumcurvesintheFourierdomainwhilemaintainingacomparablevisualqualityinthespatialdomain.
简介:Dispersionandnonlineardistortionhaveaneffectontransmissionperformancesofopticalfibertransimissionsystems,Theschemesofdispersioncompensationandnonlineardistortionself-compensationintelecom-CATVco-networktransmissionsystemsarereported,followedbyinvestigationon(1)theimpactofdispersioncompensationfiber(DCF)onfibernonlineareffectswithacascadeoferbium-dopedfiberamplifiers(EDFAs)anddifferentdispersioncompensationschemes,(2)theimpactofthecomplexonthetotalnonlineardistortioninducedbyEDFAgaintiltandthelightsource.Asaresult,dispersioncompensationoptimalschemeandEDFAnegativegaintiltaresuggestedasasolutiontodispersioncompensationoptimalschemeandEDFAnegativegaintiltaresuggestedasasolutiontodispersioncompensationandthenonlineardistortionself-compensation.
简介:Thethermaldistortionofanopticalreflectorsurfaceduetothechangingsunlightinaspaceenvironmentwillcauseshiftandspreadingofitsreflectedfocusandtherebyinfluencetheperformanceofspace-to-groundlasercommunicationlinks.Basedonthecharacteristicsofaloworbitsatellite,thenormalshiftofaplanmirrorcausedbythermaldistortionisanalyzedwiththesoftwareoftheANSYSoffiniteelementanalysis.Ageneralexpressionofthetransmittedbeamfromadistortedreflectorsurfaceandacountingformulafortheshiftsofthefocuscenterbeforeandafterthermaldistortionarededuced.Theresultofsimulationshowsthatthemagnitudeorderofthenormalshiftoftheantennamirrorsurfacecanbeashighastensofμrad.Theworsethemirrorthermaldistortionis,thelargertheshiftofthereceivedfocuscenteris.Andthechangeoftheshiftsdoesnotobeyalinearrule.
简介:Ahybridsystemofthefuzzyc-means(FCM)clusteringalgorithmandadaptive-two-stagelinearapproximationwaspresentedfornonlineardistortioncancellationofradiofrequency(RF)poweramplifier(PA).Thismechanismcaneffectivelyeliminatenoise,adaptivelymodelPA’sinstantaneouschange,andefficientlycorrectnonlineardistortion.ThisarticleputsforwardtheFCMclusteringalgorithmforclusteringreceivedsignalstoeliminatewhitenoise,andthenusestheadaptive-two-stagelinearapproximationtofittheinversefunctionoftheamplitude’sandphase’snonlinearmappingduringthetrainingphase.Parametersofthelinearfunctionandsimilarityfunctionaretrainedusingthegradient-descentandminimummean-squareerrorcriteria.Theproposedapproach’strainingresultsisdirectlyemployedtoeliminatesamplingsignal’snonlineardistortion.Thishybridmethodisrealizedeasierthanthemulti-segmentlinearapproximationandcouldreducethereceivedsignal’sbiterrorrate(BER)moreefficiently.
简介:TheanalysisofsolarcellperformancehasbeendonebysimulatingtheexternalI-Vcharacteristicsofn^+/p/p^+singlecrystalsiliconsolarcellunderhighlightintensityand1.5airmass(AM).Thismethodallowsthemaximizationofsolarcellefficiency.Tofabricatelow-costn^+/p/p^+singlecrystalsiliconsolarcells,solidsourceofdopedphosphorousandboronwasused.
简介:Theletterproposesathree-layermanageablemediadistributionnetworksystemarchi-tecturecalledMSPnet,whichisbasedonSessionInitiationProtocol[1]andPeertoPeer(SIPP2P)technology.MSPnetperformsapplication-levelstructuredDHTroutingandresourcelocationamongdomainsandunstructuredonesindomain.Exceptformediadistribution,itcanbeusedtosupportavarietyofP2Papplications,includingvideobroadcasting,videoondemand,VoIP,etc.MSPnetiscomposedofthreelayers,namely,thesignalcontrollayer,themanagementlayer,andthemediatransportationlayer.TheMSPnetprototypeconsistsoftheSIPserver,themanagementserver,themediaserver,andthenodeUserAgent(UA).Resultsfromaprototypeexperimentinalarge-scaleInternetenvironmentshowthatMSPnetisfeasible,scalableandmanageable.
简介:地理信息系统(GIS)逐渐地正在管理数据的很大的集合,一个因此集中的数据索引不能总是提供最可伸缩的解决方案。最近,p2p(P2P)网络为以一种完全分散的方式分享信息变得很流行。在这份报纸,新混合P2P空间索引网络(HPSIN)被建议,它把分布式的空铅树与基于的分布式的哈希值桌子(DHT)相结合维持询问效率和系统负担的弦网络平衡。另外,一个简单理论模型基于为HPSIN的打开的排队网络被建立。在模型,作为M/M/1排队处理器假定每个同伴系统的基本特征被捕获,并且平均质问延期的表示在靠近的形式被获得。理论分析和数字计算结果证明那在那里存在在效率和负担平衡之间的折衷的一个最佳点。由将开始索引水平ls的合适的值放为不同网络规模和询问率,HPSIN将完成因此,延期能使适应不同P2P应用程序环境的最小的全面询问。