简介:Blindrecognitionofconvolutionalcodesisnotonlyessentialforcognitiveradio,butalsofornon-cooperativecontext.Thispaperisdedicatedtotheblindidentificationofratek/nconvolutionalencodersinanoisycontextbasedonWalsh-Hadamardtransformationandblockmatrix(WHT-BM).Theproposedalgorithmconstructsasystemofnoisylinearequationsandutilizesallitscoefficientstorecoverparitycheckmatrix.Itisabletomakeuseoffault-tolerantfeatureofWHT,thusprovidingmoreaccurateresultsandachievingbettererrorperformanceinhighrawbiterrorrate(BER)regions.Moreover,itismorecomputationallyefficientwiththeuseoftheblockmatrix(BM)method.
简介:AgeneralizedspectralGreen’sfunctionformulationofN-layersubstratestructureisgivenwiththreedimensionsources,whichisasetofclosedformformulas.Afull-waveanalysismodelforrectangularmicrostripantennascoveredwithN-dielectriclayershasbeenestablishedbyusingtheabovespectralGreen’sfunction.Theunknownsurfacecurrentdensityontheniicrostrippatchforsuchstructureisfoundasasolutionofanintegralequation.TheinputVSWRandradiationpatternsoftheantennaarealsoobtained.Thenumericalresultshavebeenverifiedbytheexperimentalresults.
简介:Coexistenceandinteroperabilitybetween20MHzand40MHzdeviceandmodesofop-erationsarestressedinstandardIEEE802.11nsystem.Itismandatetoreportthebothsub-channelsstatestoMediumAccessControl(MAC)atreceiver,sincefor40MHzdevice,itshouldservenotonly20MHzbutalso40MHzsignalsreceiving.Bothenergydetectionandcarriersenseareemployedtodetectchannelstate.Inthecaseof20/40Mmode,thepowerdifferencebetweenthetwosub-channelsisalsodetectedinordertoreportthechannelstateaccurately.Thesimulationresultsdemonstratethattheperformanceoftheproposedmethodsaremuchbetterthanthemethodswhichjustemployenergydetection.Besides,thesimulationresultsshowthattheproposedmethodsensurethatthechannelsensingisnotaroadblockofIEEE802.11nsystemdesign.
简介:TheanalysisofsolarcellperformancehasbeendonebysimulatingtheexternalI-Vcharacteristicsofn^+/p/p^+singlecrystalsiliconsolarcellunderhighlightintensityand1.5airmass(AM).Thismethodallowsthemaximizationofsolarcellefficiency.Tofabricatelow-costn^+/p/p^+singlecrystalsiliconsolarcells,solidsourceofdopedphosphorousandboronwasused.
简介:Digitalsignatureisoneofthemostimportantcryptographicprimitives.WeproposedanewdigitalsignatureschemebasedonCatalano’strapdoor.SinceCatalano’strapdoorismoreefficientthanexistingtrapdoorsinnumbertheory,ourschemeneednotmodularexponentiationbutseveralmodularmultiplicationsinthesigningalgorithm.Wealsoprovedourschemeisprovablysecureagainstadap-tivelychosenmessageattackbyusingtheForkinglemma.
简介:CRTCornercuttingtubeisconsideredasadefinitiverejectandwillbesenttoreclaimatalltimes.Itcausedlotsofmaterialloss.Inthispaper,anoveltechnologyusedtosaveCRTscornercuttingtubeispresentedfirstly.AsetofrepairsystemhasbeensuccessfullydevelopedtorepairCRTscornercuttingtube.Then,theprocesstechnologyforcornercuttingrepairhasbeenexcogitatedbyempiricalstudies.Finally,thecorrelativeperformancesofrepairedtubeareevaluated.Theexperimentalresultsshowthatthequalityofrepairedtubehasnodifferencewiththatofnormalproduct.Therepairyieldhasreachedabove97percent.Thisnewtechnologyhascontributedtoimprovingtheproductionyield,reducingthematerialconsumptionanddecreasingthecostofcolorCRTproduction.
简介:Thisletterintroducesthedesignideas,simulationandtestresultsofanS-bandklystronwithbandwidthof11%,whichwasdevelopedbytheInstituteofElectronics,ChineseAcademyofSciences(IECAS).Onthepeakpowerlevelof800kW,theefficiencyofklystronismorethan30%;thegainismorethan41dB;theequal-drivingrelativeinstantaneousbandwidthisover11%;theaveragepowerislargerthan8kW,andthepowerfluctuationwithinbandwidthislessthan1.5dB.
简介:ThispaperinvestigatesthedesignofdigitalSigma-DeltaModulator(SDM)forfractional-Nfrequencysynthesizer.CharacteristicsofSDMsarecomparedthroughtheoryanalysisandsimulation.Thecurveofmaximum-loop-bandwidthvs.maximum-phase-noiseissuggestedtobeanewcriteriontotheperformanceofSDM,whichgreatlyhelpsdesignerstoselectanappropriateSDMstructuretomeettheirrealapplicationrequirementsandtoreducethecostaslowaspossible.Alow-spur3-orderMul-tistageNoiseShaping(MASH)-1-1-1SDMusingthree2-bitfirst-ordercascadedmodulatorsisproposed,whichbalancestherequirementsoftone-freeandmaximumoperationfrequency.
简介:ThecharacteristicofEDFAinWDMsystemisanalyzed.ThesimulationsystembasedonthearchitectureoftheChinaInformationNetwork(CAINONET)isintroduced,andtheinfluenceofnoisefigure,gainunflatnessandoutputpowerofEDFAontheBERperformanceandscaleofnetworkisinvestigated.Moreover,theinfluenceofnoisefigureisstudiedwithdifferentcrosstalk.Meanwhile,itisindicatedthatitisimportanttoapplythe"nodeisolationprinciple"intheopticalnetwork.Theresearchresultscanprovidethevaluablereferenceforthepracticalconstructionofallopticalnetwork.
简介:ThemicrostructureandopticalpropertiesofaburiedlayerformedbyO+(200keV,1.8×1018/cm2)andN+(180keV,4×1017/cm2)co-implantationandannealedat1200℃for2hhavebeeninvestigatedbyAugerelectron,IRabsorptionandreflectionspectroscopicmeasurements.TheresultsshowthattheburiedlayerconsistsofsilicondioxideandSiOx(x<2)andthenitrogensegregatestothewingsoftheburiedlayerwhereitformsanoxynitride.BydetailtheoreticalanalysisandcomputersimulationoftheIRreflectioninterferencespectrum,therefractiveindexprofilesoftheburiedlayerwereobtained.
简介:ByanalyzingthemainrecombinationmechanismsinGaInAsSbmaterials,thedependencesofthedarkcurrentdensityandopencircuitvoltageinn+-pGaInAsSbthermophotovoltaiccellsontherecombinationparameters,carrierconcentrationandcellthicknessarecalculated.Theresultsshowthatthedarkcurrentmainlycomesfromp-region,anditisrelatedwiththesurfaceandAugerrecombinationsinlowandhighcarrierconcentrationranges,respectively.ThesurfaceandAugerrecombinationscanbesuppressedbyreducingthesurfacerecombinationvelocityandcarrierconcentration,respectively.Thedarkcurrentdensitycanbesuppressedbyoptimizingmaterialparametersanddevicesurfacepassivationtechnique.SothehighopencircuitvoltagecanbeobtainedforGaInAsSbthermophotovoltaiccells.
简介:ThislettergivesarandomconstructionforLowDensityParityCheck(LDPC)codes,whichusesaniterativealgorithmtoavoidshortcyclesintheTannergraph.TheconstructionmethodhasgreatflexiblechoiceinLDPCcode'sparametersincludingcodelength,coderate,theleastgirthofthegraph,theweightofcolumnandrowintheparitycheckmatrix.ThemethodcanbeappliedtotheirregularLDPCcodesandstrictregularLDPCcodes.Systemiccodeshavemanyapplicationsindigitalcommunication,sothisletterproposesaconstructionofthegeneratormatrixofsystemicLDPCcodesfromtheparitycheckmatrix.Simulationsshowthatthemethodperformswellwithiterativedecoding.