简介:Alargeclassoflinearstructuralfunctions(LSF)satisfyingtheconditionofcorrelationalimmunityoforderoneareconstructedbystudyingthelinearstructuralBooleanfunctions.Withthesenewfoundedfunctions,theknownenumerationboundsofcorrelation-immunefunctionsoforderonearegreatlyimproved.Infact,thebest,uptonow,lowerboundisfound.
简介:ItiswellknownthatthealgebraicexpressionofASSS-boxisverysimpleandonly9termsareinvolved.Hence,AESsecurityissuspectedalthoughthereisnovulnerabilityonitsofar.ToeliminatetheweaknessofextremelysmalltermsinthealgebraicexpressionofAESS-box,oneimprovedAESS-boxisproposed,whichpreservesthealgebraicdegreeinvariablebutsignificantlyincreasesthenumberofitsalgebraicexpressiontermsfrom9to255.Atthesametime,Booleanfunctionhasgoodcharactersinbalanceandstrictavalanchecriterion(SAC),etc.Finally,itisprovedthattheimprovedAESS-boxschemeissecuregainstthepowerfulknowndifferentialandlinearcryptanalysis.
简介:Amagneto-photoniccrystal(MPC)isdefinedasaperiodiclight-guidedstructureinvolvingmagneticmaterialsoraphotoniccrystalwithsomemagnetic-materialdefects.Thetransfermatricesofguidedopticalwaves(GOWs)propagatingrespectivelyinmagneto-opticalandnon-magneticdielectriclayersarededucedaccordingtothecoupled-modetheory.ThetransmissionspectraofGOWsinone-dimensionalmagneto-photoniccrystals(1D-MPC)areinvestigatedbythetransfermatrixmethod.Itisshownthatthetwosharppeaksinthe1D-MPC'stransmissionspectracanbeusedforhigh-resolutionmagneticfieldsensing;andacombfilterwithsixchannelscanbeachievedbyoptimizingthe1D-MPCstructureandcontrollingtheexternalmagneticfield.
简介:Atunablephotoniccrystal(PC)filterisproposedwiththetwistednematic(TN)liquidcrystal(LC)asadefectlayer.Thepolarizationsensitiveperformanceandtheeigenmodesareanalyzed.Theresultsshowthattherearetwokindsoftransmissionmodes,namelyoande,whenthevoltageislow.Thedifferentmodescanbeselectedbyrotatingthefilteraxially.Theemodeshiftstowardtheshorterwavelengthsideastheappliedvoltageincreases.Thenthepeaksoftwomodesmergeintoeachotherandthepolarizationsensitiveperformancedisappears.Thephotonicbandgapisinsensitivetothevoltage.Thetunablerangeofthefilteris53nm.
简介:Thispaperintroducesdecimatedfilterbanksfortheone-dimensionalempiricalmodedecomposition(1D-EMD).Thesefilterbankscanprovideperfectreconstructionandallowforanarbitrarytreestructure.SincetheEMDisadatadrivendecomposition,itisaveryusefulanalysisinstrumentfornon-stationaryandnon-linearsignals.However,thetraditional1D-EMDhasthedisadvantageofexpandingthedata.Largedatasetscanbegeneratedastheamountofdatatobestoredincreaseswitheverydecompositionlevel.The1D-EMDcanbethoughtashavingthestructureofasingledyadicfilter.However,amethodologytoincorporatethedecompositionintoanyarbitrarytreestructurehasnotbeenreportedyetintheliterature.Thispapershowshowtoextendthe1D-EMDintoanyarbitrarytreestructurewhilemaintainingtheperfectreconstructionproperty.Furthermore,thetechniqueallowsfordownsamplingthedecomposedsignals.Thispaper,thus,presentsamethodtominimizethedata-expansiondrawbackofthe1D-EMDbyusingdecimationandmergingtheEMDcoefficients.Theproposedalgorithmisapplicableforanyarbitrarytreestructureincludingafullbinarytreestructure.
简介:Oneofthemainrequirementsofcognitiveradiosystemsistheabilitytodetectthepresenceoftheprimaryuserwithfastspeedandpreciseaccuracy.Toachievethat,apossibletwo-stagespectrumsensingschemeissuggestedinthispaper.Morespecifically,afastspectrumsensingalgorithmbasedontheenergydetectionisintroducedfocusingonthecoarsedetection.Acomplementaryfinespectrumsensingalgorithmadoptsone-ordercyclostationarypropertiesofprimaryuser'ssignalsintimedomain.Sincetheone-orderfeaturedetectionisperformedintimedomain,thereal-timeoperationandlow-computationalcomplexitycanbeachieved.Also,itdrasticallyreduceshardwareburdensandpowerconsumptionasopposedtotwo-orderfeaturedetection.Thesensingperformanceoftheproposedmethodisstudiedandtheanalyticalperformanceresultsaregiven.Theresultsindicatethatbetterperformancecanbeachievedinproposedtwo-stagesensingdetectioncomparedtotheconventionalenergydetector.
简介:Weintroduceanewmodelofone-dimensional(1D)photoniccrystalcomposedofalternatelyarrangedRHMandLHMlayerswithpositiveandnegativerefractiveindicesrespectively,forwhichthetransmissionspectraofthemodelarecalculatednumericallywiththetransfermatrixmethod,andtheband-gapstructureandthepolarizationpropertiesareanalyzed.Wefoundthattheintroductionofnegativerefractiveindexlayers(i.e.LHMmediumlayers)givesrisetosomepeculiarband-gapstructureandpolarizationpropertiesasfollows.Firstly,theforbiddenbandsareextremelywideandthetransmissionbandsareverysharpwithoutoscillation;andsecondly,thechangeofincidentanglehasdifferentinfluencesontheforbiddenbandsofTEandTMmodes.FortheTMmode,theforbiddenbandwidthdecreasessubstantiallyandfinallyvanishes,andfortheTEmodewithcentralwavelength,thetotalreflectionhappensatanyincidentangle.