简介:Alocalizedparametrictime-shearedGaboratomisderivedbyconvolvingalinearfrequencymodulatedfactor,modulatinginfrequencyandtranslatingintimetoadilatedGaussianfunction,whichisthegeneralizationofGaboratomandismoredelicateformatchingmostofthesignalsencounteredinpractice,especiallyforthosehavingfrequencydispersioncharacteristics.Thetime-frequencydistributionofthisatomconcentratesinitstimecenterandfrequencycenteralongenergycurve,withthecurvebeingobliquetoacertainextentalongthetimeaxis.Anovelparametricadaptivetime-frequencydistributionbasedonasetofthederivedatomsisthenproposedusingaadaptivesignalsubspacedecompositionmethodinfrequencydomain,whichisnon-negativetime-frequencyenergydistributionandfreeofcross-terminterferenceformulticomponentsignals.Theresultsofnumericalsimulationmanifesttheeffectivenessoftheapproachintime-frequencyrepresentationandsignalde-noisingprocessing.
简介:一种技术把重叠频率时间分割称为multiplexing(OVFTDM))在这篇文章被建议。这种技术从Nyquist系统和频率时间部门multiplexing系统被导出。没有orthogonality,信号是什么时候,简洁地及时重叠了领域,,当没有orthogonality,信号简洁地在频率领域被重叠时,这种技术被称为重叠时间部门multiplexing(OVTDM),这种技术被称为重叠频率部门multiplexing(OVFDM)。进一步改善光谱效率,在哪个发信号的OVFTDM在频率领域两个都被重叠,及时,域被探索。OVFTDM不取决于无论什么的orthogonality及时域或在象Nyquist系统或OFDM系统一样的频率领域,但是在在信号之中的convolutional限制关系上。因此,不是仅仅光谱效率而且可靠性被改进。模拟验证这个理论的有效性。
简介:Thispaperpresentsanoveltimedelayestimation(TDE)methodusingtheconceptofentropy.Therelativedelayisestimatedbyminimizingtheestimatedjointentropyofmultiplesensoroutputsignals.Whenestimatingtheentropy,theinformationaboutthepriordistributionofthesourcesignalisnotrequired.Instead,theParzenwindowestimatorisemployedtoestimatethedensityfunctionofthesourcesignalfrommultiplesensoroutputsignals.Meanwhile,basedontheParzenwindowestimator,theRenyi’squadraticentropy(RQE)isincorporatedtoeffectivelyandefficientlyestimatethehigh-dimensionaljointentropyofthemultichanneloutputs.Furthermore,amodifiedformofthejointentropyforembeddinginformationaboutreverberation(multipathreflections)forspeechsignalsisintroducedtoenhancetheestimator’srobustnessagainstreverberation.
简介:Operationalsoftwaresystemsoftenexperiencean'aging'phenomenon,characterizedbyprogressiveperformancedegradationandasuddenhang/crashfailure.Softwarerejuvenationisaproactivefault-tolerancestrategyaimedtopreventunexpectedoutagesduetoaging.Anewrejuvenationstrategybasedonmeasurementandtime,andconstructsaSRNmodeltoevaluatethisstrategy.Numericalresultsshowthatthisstrategyoutweighseitherthepurelymeasurementbasedorthepurelytime-basedstrategyandcaneffectivelyimprovesystemperformance.
简介:Theequationoftime-domainwavepropagationindispersivemediaandtheexplicitbeampropagationmethodarepresentedinthispaper.Thismethodisdemonstratedbytheshortopticalpulsesinadirectionalcouplerwithsecondorderdispersiveeffectandshowstobeinfullagreementwithformerreferences.Thismethodissimple,easyandpractical.
简介:Theterahertztime-domainspectroscopy(THz-TDS)systemandtherelatedtechnologyandtheapplicationsinCapitalNormalUniversityarepresented.ThemostoftenusedTHz-TDSsystemasaspectroscopicmeasurementsetupinourlabisintroducedindetail,includingtheTHzradiationsource,theTHzdetectionmethodanditsmeasurement,andthecontrolsystem.THzspectraofvariousmaterialsissummarizedanddiscussed.Thesematerialsincludebutnotlimitedtotwokindsoftypicalmatter—theillegaldrugsandexplosives.Thebiologicalmacro-molecules,cosmeticsandfinechemicalmaterials,ediblepigmentsandfoodadditives,homocysteicacidandrelatedcompounds,heavyionsinsoil,Chinesemedicines,tobaccoandcrops,oilandchemicalproducts,carbonnanotubes,superconductors,andvarioussemiconductorsandtheirheterojunctions,arepresented.THzemissionsfromtheInAsandInNsemiconductorssurfacearecompared.THzspectralinvestigationofmetallicmeshstructuresissummarized.Finally,anoutlookofTHzspectroscopicapplicationsisgiven.
简介:BasedontheComplexOrthogonalLinearDispersion(COLD)code,anovellinearDiffer-entialSpace-TimeModulation(DSTM)designisproposedinthispaper.ComparedwiththeexistingnonlinearDSTMschemesbasedongroupcodes,theproposedlinearDSTMschemeiseasiertodesign,enjoysfulldiversityandallowsforasimplifieddifferentialreceiver,whichcandetectthetransmittedsymbolsseparately.Furthermore,comparedwiththeexistinglinearDSTMbasedonorthogonaldesign,ournewconstructioncanbeappliedtoanynumberoftransmitantennas.Similartootheralgorithms,theproposedschemealsocanbedemodulatedwithorwithoutchannelestimatesatthereceiver,buttheperformancedegradesapproximatelyby3dBwhenestimatesarenotavailable.
简介:Time-domainWavePropagationinDispersiveMedia①JUZhenle,FUJunmei,FENGEnxin(InstituteofMicrowaveEnginering&OpticalCommunicationTe...
简介:Aninfraredreal-timeimagingsystemusingDSP(digitalsignalprocessor)asthekernelofdigitalsignalprocessingboardispresented.Inthissystem,theimagingdifferenceandnonuniformitycorrectionmethodisdevelopedonthechiptakingadvantageofDSPwithhighspeed.Themethodcombineshardwareandsoftwaretogether,sothatthedifficultyforrealizingsuchamethodwithotherhardwarecanbeovercome.
简介:Inordertoachievetheinformationfusioninthetimedomainbasedontheevidencetheory,anevidencecombinationmethodinthetimedomainbasedonreliabilityandimportanceisproposedaccordingtotheideaofevidencediscount.Firstly,thedistortionofthetime-domainevidenceisjudgedbasedonsingleexponentialsmoothing.Thereal-timereliabilityoftheevidenceattheadjacenttimeisobtainedbythereal-timereliabilityassessmentmethodoftheevidencebasedonthecredibilitydecaymodel.Then,therelativeimportanceoftheevidenceattheadjacenttimeisobtainedbycomprehensivelyconsideringimprovedconflictdegreeanduncertainty.Finally,basedonthecriterionofevidencediscountandtheDempster’sruleofcombination,theevidencecombinationiscarriedouttoachievethesequentialcombinationoftime-domainevidence.Thenumericalsimulationandanalysisshowthatthismethodhasfullyembodiedthedynamiccharacteristicsoftime-domainevidencecombination,andithasstrongprocessingabilityforconflictinformationandanti-disturbingability.Theproposedmethodhasgoodapplicabilitytoinformationfusioninthetimedomain.
简介:Thestatisticcharacteristicsofchaoticsequencesgeneratedbyimprovedlogistic-mapareanalyzedanditisfoundthatimprovedlogistic-mapchaoticsequenceshavegoodcorrelationandtheycanbeusedasaddresssequencesinspread-spectrumcommunication.Thediscrete-timesynchronizationofHenonmapisimmediate.Weapplythediscrete-timesynchronizationtochaoticspread-spectrumcomuunicationandproposeanoriginalcommunicationscheme.Thesimulationshowsthattheapplicationissuccessful.
简介:Twocomplexproperties,varyingtime-delayandblock-orientednonlinearity,areverycommoninchemicalengineeringprocessesandnoteasytobecontrolledbyroutinecontrolmethods.Aimedatthesetwocomplexproperties,anoveladaptivecontrolalgorithmthebasisofnonlinearOFS(orthonormalfunctionalseries)modelisproposed.First,thehybridmodelwhichcombinesOFSandVolterraseriesisintroduced.Then,astablestatefeedbackstrategyisusedtoconstructanonlinearadaptivecontrolalgorithmthatcanguaranteetheclosed-loopstabilityandcantrackthesetpointcurvewithoutsteady-stateerrors.Finally,controlsimulationsandexperimentsonanonlinearprocesswithvaryingtime-delayarepresented.Anumberofexperimentalresultsvalidatetheefficiencyandsuperiorityofthisalgorithm.
简介:Adifferentialmodulationschemeusingspace-timeblockcodesisputforward.Comparedwithotherschemes,ourschemehaslowercomputationalcomplexityandhasasimplerdecoder.Inthecaseofthreeorfourtransmitterantennas,ourschemehasahigherrateahighercodinggainandalowerbiterrorrateforagivenrate.Thenwemadesimulationsforspace-timeblockcodesaswellasgroupcodesinthecaseoftwo,three,fourandfivetransmitantennas.Thesimulationsprovethatusingtwotransmitantennas,onereceiveantennaandcoderateof4bits/s/Hz,thedifferentialSTBCmethodoutperformthedifferentialgroupcodesmethodby4dB.Useingthree,fourandfivetransmitantennas,onereceiveantenna,andcoderateof3bits/s/Hzareadopted,thedifferentialSTBCmethodoutperformthedifferentialgroupcodesmethodby5dB,6.5dBand7dB,respectively.Inotherwords,thedifferentialmodulationschemebasedonspace-timeblockcodeisbetterthanthecorrespondingdifferentialmodulationscheme
简介:Terahertz(THz)radiation,whosefrequencyrangesfrom0.1THzto10.0THz,hasrichscience,butlimitedtechnology.Ithaslongbeenconsideredthelastremainingscientificgapintheelectromagneticspectrum.Farfrombeingfullyexploited,itoffersgreatopportunitiesinscience,innovation,newtechnology,andpotentialapplications.
简介:Coverageholesoftenappearinwirelesssensornetworksduetosensorfailureortheinheritanceofsensor'srandomdistribution.Inthehybridmodel,mobilesensorsinthenetworkareacquiredtohealcoverageholesbytheirmobility.Whenmultiplecoverageholesappearinthesensornetworkandeachofthemhasatimerequirement(inwhichthecoverageholehastobehealed),conflictsfortherequestsofthesamemobilesensormayarise.Adistributedmultiplemobilesensorschedulingprotocol(DMS)isproposedinthispapertosolvethisproblembyfindingmobilesensorsinthetimeresponsezonedefinedbythetimerequirementofeachcoveragehole.SimulationresultsshowthatDMScanwellschedulethemobilesensorstomovetomultiplecoverageholeswithinthetimerequirement.
简介:Inthispaper,globalasymptoticstabilityforcellularneuralnetworkswithtimedelayisdiscussedusinganovelLiapunovfunction.Somenovelsufficientconditionsforglobalasymptoticstabilityareobtained.ThoseresultsaresimpleandpracticalthanthosegivenbyP.P.Civalleri,etal.,andhavealeadingimportancetodesigncellularneuralnetworkswithtimedelay.
简介:Thispaperdescribesamulti-threatreal-timeseparatingsystemforbroadbandanti-radiationmissileseeker.Itpresentsamethod,withadual-portmemoryascomparer,toperformPFandPWhardwarereal-timeseparationandtodeterminethetime-of-arrival(TOA)byuseofsequentialdifferencehistogram(SDIF).Themethodhasbeenappliedtopractice,whichhasachievedgoodresults.