简介：TheelectromagneticpropagationthroughaninhomogeneousmagnetizedplasmaslabisstudiedusingtheZ-transformformulationoftheFinite-DifferenceTime-Domain(FDTD)method.Thedirectionofelectromagneticpropagationisparalleltothebiasingmagneticfiled.TovalidatetheZ-transformalgorithm,thereflectionandtransmissioncoefficientsfortheright-handcircularlypolarizedwaveofthehomogeneousmagnetizedplasmaslabarecomputedbymeansofdiscreteFouriertransform.ThecomparisonbetweenthereflectionandtransmissioncoefficientsofthehomogeneousplasmaslabandanalyticalvaluesindicatesthatZ-transformalgorithmisveryaccurate.Whentheplasmafrequencyvariesaccordingtothesquarerootandparabolicrelations,thereflectionandtransmissioncoefficientsoftheinhomogeneousmagnetizedplasmaslabarecomputed.

简介：

简介：Performancerobustnessproblemsviathestatefeedbackcontrollerareinvestigatedforaclassofuncertainnonlinearsystemswithtime-delayinbothstateandcontrol,inwhichtheneuralnetworksareusedtomodelthenonlinearities.Byusinganappropriateuncertaintydescriptionandthelineardifferenceinclusiontechnique,sufficientconditionsforexistenceofsuchcontrollerarederivedbasedonthelinearmatrixinequalities(LMIs).UsingsolutionsofLMIs,astatefeedbackcontrollawisproposedtostabilizetheperturbedsystemandguaranteeanupperboundofsystemperformance,whichisapplicabletoarbitrarytime-delays.

简介：Thetracking,telemetryandcommand(TT&C)missionisextremelyreliableforitscharactersofsmalltimehorizonandhighredundancy.Thecombinedforcingandfailurebiasing(CFFB)methodthatisusuallyusedforsimulatingtheunreliabilityofthehighlydependablemissionsystemseemsnotsoefficientfortheTT&Cmission.TheconceptabouttheimportanceoffailuretransitionisproposedbasedonthelogicalrelationshipbetweenTT&Cmissionanditsinvolvedresources.Then,theimportanceisusedforreadjustingthetransitionrateofthefailuretransitionwhenusingtheforcingandfailurebiasingduringthesimulation.ExamplesshowthattheimprovedCFFBmethodcanevidentlyincreasetheoccurrenceoftheTT&Cmissionfailureeventanddecreasethesamplevariance.MoreredundancyoftheTT&CmissionleadstotheimprovedCFFBmethodmoreefficient.

简介：Theimpactanglecontroloverguidance(IACG)lawagainststationarytargetsisproposedbyusingfeedbacklinearizationcontrol(FLC)andfinitetimecontrol(FTC).First,thispapertransformsthekinematicsequationofguidancesystemsintothefeedbackablelinearizationmodel,inwhichtheguidancelawisobtainedwithoutconsideringtheimpactangleviaFLC.Forthepurposeofthelineofsight(LOS)angleanditsrateconvergingtothedesiredvalues,thesecond-orderLOSangleisconsideredasadouble-integralsystem.Then,thispaperutilizesFTCtodesignacontrollerwhichcanguaranteethestatesofthedouble-integralsystemconvergingtothedesiredvalues.NumericalsimulationillustratestheperformanceoftheIACG,incontrasttotheexistingguidancelaw.

简介：

简介：Time-to-DigitalConverter(TDC)isakeyblockusedasthephase/frequencydetectorinanAll-DigitalPhase-LockedLoop(ADPLL).Usually,itoccupiesalargeproportionofADPLL'stotalpowerconsumptionuptoabout30%to40%.Inthispaper,thedetailedpowerconsumptionofdifferentcomponentsintheTDCisanalyzed.APowerManagementBlock(PMB)ispresentedfortheTDCtoreduceitspowerconsumption.A24-bitsTDCcorewiththeproposedPMBisimplementedinHJTC0.18μmCMOStechnology.Simulationresultsshowthatupto84%powerreductionisachievedusingourproposedtechnique.

简介：Givenanon-equidistantsequenceoranequidistantserieswithoneormoreoutliers,agreyinterpolationapproachconsideringthetimelagsisestablishedforproducingthemissingdataorcorrectingtheabnormalvalues.Toaccomplishthis,anewgreyincidencemodel,calledthegreydynamicincidencemodelGDIM(t),isconstructedfordeterminingwhetherthefactorsareeffectivetotheknownfactorandwhatthetimelagisbetweenausefulfactorandthespecifiedsequence.BasedontheresultsoftheGDIM(t)model,twoprogrammingproblemsaredesignedtoobtaintheupperandlowerboundsoftheunknownorabnormalvalueswhichareregardedasgreynumbers.Thesolutionsbasedontheparticleswarmoptimization(PSO)forthenonlinearprogrammingproblemsaregiven.Toexplainhowitcanbeusedinpractice,thisnewgreyinterpolationapproachisappliedtocorrectanabnormalvalueinthesequenceofanagricultureenvironmentproblem.

简介：Space-TimeBlock(STB)codehasbeenaneffectivetransmitdiversitytechniqueforcombatingfadingduetoitsorthogonaldesign,simpledecodingandhighdiversitygains.Inthispaper,aunit-ratecomplexorthogonalSTBcodeformultipleantennasinTimeDivisionDuplex(TDD)modeisproposed.Meanwhile,TurboCoding(TC)isemployedtoimprovetheperformanceofproposedSTBcodefurtherbyutilizingitsgoodabilitytocombatthebursterroroffadingchannel.Comparedwithfull-diversitymultipleantennasSTBcodes,theproposedcodecanimplementunitrateandpartialdiversity;andithasmuchsmallercomputationalcomplexityunderthesamesystemthroughput.Moreover,theapplicationofTCcaneffectivelymakeupfortheperformancelossduetopartialdiversity.SimulationresultsshowthatontheconditionofsamesystemthroughputandconcatenationofTC,theproposedcodehaslowerBitErrorRate(BER)thanthosefull-diversitycodes.

简介：Theoptimizationofthefiber-coupledterahertztime-domainspectroscopy(THz-TDS)systemisperformedbychangingthepolarizationoftheopticalexcitationpulsecenteredat1550nm.InGaAs/InAlAsmultilayerstructuresbasedphotoconductiveantennasareusedinTDSsetupasboththeemitterandreceiver.TheexperimentalresultsdemonstratethatnotonlytheTHzsignalpowerbutalsothetemporalwaveformvarywiththerotationoftheexcitingpulsepolarization.Maximumoutputpoweroftheemitterisobtainedwhenthepolarizationofthepumppulseisperpendiculartotheedgeofthemetalelectrodes.AtthismomenttheTHzwaveformisclosetoasingle-cycledpulse.However,doubleTHzpulsescouldberecordedwhenthepumplaserpolarizationisparalleltotheelectrodes.Laserpulsesplittinginducedbythebirefringenceoftheopticalfibermayattributetothepolarizationdependentperformanceofthefiber-coupledTHz-TDSsystem.

简介：

简介：ThispaperinvestigatesaMultiple-InputMultiple-Output(MIMO)schemecombiningTransmitAntennaSelectionandreceiveMaximal-RatioCombining(TAS/MRC)intime-varyingRayleighfadingchannels.Wefirstpresentnewclosed-formexpressionsforoptimalreceivedSignal-to-NoiseRatio(SNR),whichisexpressedinpolynomialform.Theseareusedtoanalyzeergodiccapacity,outageprobabilityandBitErrorRate(BER)ofTAS/MRCsystems.Numericalresultsarepresentedtovalidatethetheoreticalanalysis.

简介：

简介：Thispaperconstructsasimulationsystemofnear-fieldlaserimagingfor3Dgridmodeloftarget,providessomemethodsforthekeyproblems,suchasthemodelingoftargetandlasertransceiver,thecalculationoflaserechopower,theimagingalgorithmsandsoon.Atargetimagelibraryisestablishedbyanewimagingmethodinanyrendezvousconditions.Thefourreal-timerecognitionalgorithmswhichareefficientandsuitableforhardwareimplementationarepresentedattheconditionsoftheimageincompleteness,intensivenoiseandarbitraryattitudeoftarget.Theexperimentalresultsshowthatallthefouralgorithmscanindependentlyrecognizethetargeteffectivelyandabetterrecognitioneffectisobtainedbytheintegrationoffouralgorithms.

简介：TheionospherictimedelayisoneofthemainerrorsourcesinC/AcodeGPSnavigationandpositioningapplications.Inthispaper,amethodisproposedforreal-timedual-frequencyionospherictime-delaycorrectingusingaC/AcodeGPSreceiver,andtheprincipleofthecircuitblockdiagramforthismethodisanalyzedwithitsfeasibilitytheoreticallydemonstrated.

简介：GaNmicrocrystallinegrainsweregrownbyhot-wallchemicalvapordepositiononSi(111)substrate.Thesegrainswithdiametersof2-4μmweredetectedbyscanningelectronmicroscopy.X-raydiffraction,Fouriertransformationinfraredtransmissionspectroscopyandphotoluminescencewereusedtoanalyzethestructure,compositionandtheopticalpropertiesofthesamples.TheresultsshowthatthemicrocrystallinegrainsarehexagonalwurtziteGaN,andthepropertyofthegrainswasgreatlyaffectedbythegrowthtime.

简介：Asanimportantapplicationresearchtopicoftheintelligentaviationmulti-station,collaborativedetectingmustovercometheproblemofscoutingmeasurementwithstatusof“fragmentation”,andtheNP-hardnessproblemofmatchingassociationbetweentargetandmeasurementintheprocessofscoutingtodata-link,whichhascomplicatedtechnicalarchitectureofnetworkconstruction.Inthispaper,takingadvantageofcooperationmechanismonsignallevelintheaviationmulti-stationsympatheticnetwork,amethodofobtainingtargettimedifferenceofarrival(TDOA)measurementusingmulti-stationcollaborativedetectingbasedontime-frequencyassociationisproposed.Themethodcannotonlyachievematchingbetweentargetanditsmeasurement,butalsoobtainTDOAmeasurementbyfurtherevolutionarytransactionthroughrefreshingsequentialpulsetimeofarrival(TOA)measurementmatrixformatchingandcorrelating.SimulationresultsshowthattheaccuracyofTDOAmeasurementhassignificantsuperiorityoverTOA,anddetectionprobabilityoffalseTDOAmeasurementintroducedbynoiseandfakemeasurementcanbereducedeffectively.

简介：Byemployingaradiofrequency(RF)feedbackchain,theself-interferencecanbecanceledefficientlyinco-timeco-frequencyfullduplex(CCFD).However,theevitablesignalcrosstalkwhichiscausedbytheimperfectRFfeedbackchainisolationusuallydamagestheself-interferencecancelation(SIC)performance.Todealwiththisproblem,firstly,weanalyzetheimpactofRFfeedbackchainisolationonSICperformance.ThenadigitalpreprocessingschemewithRFfeedbackchainisproposedinthemultiple-antennaCCFDarchitecture.Usingbothanalyticalandexperimentalmethods,wefindthattheproposedschemeachievesabetterperformanceonSIC.

简介：ThispaperfocusesontheH∞controllerdesignforlinearsystemswithtime-varyingdelaysandnormboundedparameterperturbetionsinthesystemstateandcontrol/disturbance.Ontheexistenceofdelayed/undelayedfullstatefeedbackcontrollers,wepresentasufficientconditionandgiveadesignmethodintheformofRiccatiequation.Thecontrollercannotonlystabilizethetime-delaysystem,butalsomaketheH∞normoftheclosed-loopsystembelessthanagivenbound.Thisresultpracticallygeneralizestherelatedresultsincurrentliterature.

简介：UsingTime-VaryingAR(TVAR)modelandadaptivenotchfilterisanewmethodforthenon-stationaryjammersuppressioninDirectSequenceSpreadSpectrum(DSSS).TheperformanceofTVARmodelforInstantaneousFrequency(IF)estimationwillbeaffectedbysomefactorssuchasbasisfunctions.Focusingonthisproblem,theoptimalbasisfunctionofTVARmodelfortheIFestimationoftheLFMsignalisobtainedinthispaper.Besidesthedepthandwidthofnotching,thephasepropertiesofnotchfilteraffecttheSignal-to-Interferenceplus-NoiseRatio(SINR)ofcorrelationoutputtothenarrowbandjammersuppressioninDSSS,inresponsetotheproblemtheclosedsolutionofcorrelationoutputSINRimprovementhasbeenderivedwhenasinglefrequencyjammerpassesthroughdirectIIRnotchfilter,anditsperformancehasbeencomparedwiththoseoffivecoefficientFIRfilters.Later,anovelmethodforLFMjammersuppressionbasedonFourierbasisTVARmodelanddirectIIRnotchfilterisproposed.Thesimulationresultsshowtheeffectivenessoftheproposedmethod.