学科分类
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26 个结果
  • 简介:Reversibledatahidingtechniquesarecapableofreconstructingtheoriginalcoverimagefromstego-images.Recently,manyresearchershavefocusedonreversibledatahidingtoprotectintellectualpropertyrights.Inthispaper,wecombinereversibledatahidingwiththechaoticHénonmapasanencryptiontechniquetoachieveanacceptablelevelofconfidentialityincloudcomputingenvironments.And,Haardigitalwavelettransformation(HDWT)isalsoappliedtoconvertanimagefromaspatialdomainintoafrequencydomain.Andthenthedecimalofcoefficientsandintegerofhighfrequencybandaremodifiedforhidingsecretbits.Finally,themodifiedcoefficientsareinverselytransformedtostego-images.

  • 标签: 数据隐藏 医学图像 计算环境 可逆 混沌 HAAR小波变换
  • 简介:Animprovedalgorithmwhichisbasedontherecursiveclosed-formalgorithmfornon-minimumphaseFIRsystemidentificationviahigherorderstatisticsispresented.Inordertoincreasetheparametricestimationaccuracy,theimprovedalgorithmusestheoptimaliterativemethodtoseekthenonlinearleast-squaresolution.Finally,thesimulationexamplesarealsogiven.

  • 标签: Non-minimum phase FIR system HIGHER order
  • 简介:AmeasurementsystemwiththeCCDmatrixandcomputersystemisdesignedtotestthe2Dsizeofanyshapeworkpiecesautomatically.Inaddition,thesystemadoptsthemethodoftherelativemeasurementwhichincreasestheprecisionandthevelocity.Moreimportantly,theprecisioncan'tbechangedwiththeconditionsofthetemperatureandairpressure.Theexperimentsshowthattherelativeprecisionof0.0029andtheabsoluteprecisionof2.97μmareobtained.Theinstrumentmaybeusedintheproductlineandmakethetestingonlinepossible.

  • 标签: CCD矩阵 摄影目标 计算机 电荷耦合器件
  • 简介:Themechanismofanon-polarizingbeamsplitter(NPBS)withasymmetricaltransfercoefficientscausingtherotationofpolarizationdirectionisexplainedinprinciple,andthemeasurementnonlinearerrorcausedbyNPBSisanalyzedbasedonJonesmatrixtheory.Theoreticalcalculationsshowthatthenonlinearerrorchangesperiodically,andtheerrorperiodandpeakvaluesincreasewiththedeviationbetweentransmissivitiesofp-polarizationands-polarizationstates.Whenthetransmissivityofp-polarizationis53%andthatofs-polarizationis48%,themaximumerrorreaches2.7nm.TheimperfectionofNPBSisoneofthemainerrorsourcesinsimultaneousphase-shiftingpolarizationinterferometer,anditsinfluencecannotbeneglectedinthenanoscaleultra-precisionmeasurement.

  • 标签: 非线性误差 偏振分束器 移相干涉仪 极化方向 非对称 传热系数
  • 简介:ThispaperinvestigatestheuntraditionalapproachofcontentionresolutioninWavelengthDivisionMultiplexing(WDM)OpticalPacketSwitching(OPS).Themoststrikingcharacteristicsofthedevelopedswitcharchitectureare:(1)ContentionresolutionisachievedbyacombinedsharingofFiberDelay-Lines(FDLs)andTunableOpticalWavelengthConverters(TOWCs);(2)FDLsarearrangedinnon-degenerateform,i.e.,non-uniformdistributionofthedelaylines;(3)TOWCsjustcanperformwavelengthconversioninpartialcontinuouswavelengthchannels,i.e.,sparsewavelengthconversion.TheconcreteconfigurationsofFDLsandTOWCsaredescribedandanalyzedundernon-burstyandburstytrafficscenarios.Simulationresultsdemonstratethatforaprefixedpacketlossprobabilityconstraint,e.g.,10-6,thedevelopedarchitectureprovidesadifferentpointofviewinOPSdesign.Thatis,combinedsharingofFDLsandTOWCscan,effectively,obtainagoodtradeoffbetweentheswitchsizeandthecost,andTOWCswhichareachievedinsparseformcanalsodecreasetheimplementingcomplexity.

  • 标签: 光包交换 波长变换 光纤延迟线 包损失概率
  • 简介:Facerecognitionbasedonfewtrainingsamplesisachallengingtask.Indailyapplications,sufficienttrainingsamplesmaynotbeobtainedandmostofthegainedtrainingsamplesareinvariousilluminationsandposes.Non-sufficienttrainingsamplescouldnoteffectivelyexpressvariousfacialconditions,sotheimprovementofthefacerecognitionrateunderthenon-sufficienttrainingsamplesconditionbecomesalaboriousmission.Inourwork,thefacialposepre-recognition(FPPR)modelandthedualdictionarysparserepresentationclassification(DD-SRC)areproposedforfacerecognition.TheFPPRmodelisbasedonthefacialgeometriccharacteristicandmachinelearning,dividingatestingsampleintofull-faceandprofile.Differentposesinasingledictionaryareinfluencedbyeachother,whichleadstoalowfacerecognitionrate.TheDD-SRCcontainstwodictionaries,full-facedictionaryandprofiledictionary,andisabletoreducetheinterference.AfterFPPR,thesampleisprocessedbytheDD-SRCtofindthemostsimilaroneintrainingsamples.Theexperimentalresultsshowtheperformanceoftheproposedalgorithmonolivettiresearchlaboratory(ORL)andfacerecognitiontechnology(FERET)databases,andalsoreflectcomparisonswithSRC,linearregressionclassification(LRC),andtwo-phasetestsamplesparserepresentation(TPTSSR).

  • 标签: face RECOGNITION FACIAL POSE pre-recognition (FPPR)