简介:AdoublehelixmodelofchargetransportinDNAmoleculeisgivenandthetransmissionspectraoffourDNAsequencesareobtained.ThecalculatedresultsshowthatthetransmissioncharacteristicsofDNAarenotonlyrelatedtothelongitudinaltransportbutalsotothetransversetransportofmolecule.Theperiodicsequencewiththesamecompositionhasstrongerconductionability.Withtheincreasingofbasescomposition,theconductiveabilityreduces,buttheweightofθdirectionrisesinchargetransfer.
简介:Influenceofpulsedpowertransmissiononradiowaveenvironmentisinvestigated.Thepowerpulsesaretransmittedintermittentlyinpulsedpowernetworkthatisalreadyproposedforanalternativeofupcomingsmartgrids.Incontrasttoconventionalpowertransmissionwithcontinuouselectriccurrentoflowfrequencysinewave,pulsedpowertransmissionmayaffectsurroundingfieldwithhighfrequencyradionoises.Inthispaper,basedontheanalysisofelectricfieldstrengtharoundapowerline,theradionoisesgeneratedbyvariousformsofpulsedpowertransmissionareevaluated.Asaresult,twopointsarederived.First,thoughthetotalofgeneratedradionoisepowerobviouslyexceedsthatofconventionalpowertransmissions,peakstrengthofelectricfieldratherfallsbehindtheconventionalone.Second,concerningtheinfluenceontheradiowaveofthelowestfrequency40kHzthatisactuallyusedforstandardtimeandfrequencysignal,thenoiseintensitypossiblyexceedstheweakradiosignaltoleranceaccordingtotheshapeofeachpowerpulsetransmitted.
简介:Openwaveguidesarewidelyusedinmodernphotonicdevices,suchasmicrostructuredfiberfiltersandsensors.Theirabsorptionandtransmissionspectraarethemostimportantpropertiesindeterminingtheoverallperformanceofthephotonicdevices.Theimaginarypartsoftheireigenvalueshavebeencommonlyusedtocalculatetheabsorptionandconsequentlythetransmissionspectra.Hereweshowthatthisformulismisgenerallyincorrectandnotconsistentwiththesimulationresultsobtainedbythebeampropagationmethod.Werevisitthefundamentaltheoryfortheabsorptionofopenwaveguidesandpresentageneralformulism.Wefoundthatparity-time-symmetrytransitions,whichhavebeenconventionallyignored,playacriticalroleinthepropertiesofthecoupledwaveguide.Theabsorptionandtransmissionarehighlydependentonthephysicallengthofthesystem.Onthebasisofourfindings,optimizationcriteriafordesigningphotonicsensorsandfiltersarepresented.
简介:Theenergytransmissionofthelongmicrowavepulseforthefrequencyof2.45GHzand5.8GHzisstudiedbyusingtheelectronfluidmodel,wheretheratecoefficientsarededucedfromtheBoltzmannequationsolvernamedBOLSIG+.Thebreakdownthresholdsfordifferentairpressuresandincidentpulseparametersarepredicted,whichshowgoodagreementwiththeexperimentaldata.Belowthebreakdownthreshold,thetransmittedpulseenergyisproportionaltothesquareoftheincidentelectricfieldamplitude.Whentheincidentelectricfieldamplitudehigherthanthebreakdownthresholdincreases,thetransmittedpulseenergydecreasesmonotonouslyatahighairpressure,whileatalowairpressureitfirstdecreasesandthenincreases.Wealsocomparethepulseenergytransmissionforthefrequencyof2.45GHzwiththecaseof5.8GHz.
简介:HL-2Atokamakwillbeequippedwitha75GHz/1MW/1sECRHsystem.Thepaperdescribesthedesignofthetransmissionsystem(Fig.1),whichismadeupwithatransmissionline,anequatoriallauncher.Thepaperdescribesthedesignofmaincomponentsofthesystemsuchas,waveguides,ellipsoidalsurfacemirrors,achemicalvapor(CVD)diamondwindow,asteeringmirror.
简介:Taperedfiberswithdiametersrangingfrom1to4μmarewidelyusedtoexcitethewhispering-gallery(WG)modesofmicrocavities.Typically,thetransmissionspectrumofaWGcavitycoupledtoawaveguidearoundaresonanceassumesaLorentziandipmorphologyduetoresonantabsorptionofthelightwithinthecavity.Inthispaper,wedemonstratethatthetransmissionspectraofaWGcavitycoupledwithanultrathinfiber(500–700nm)mayexhibitbothLorentziandipsandpeaks,dependingonthegapbetweenthefiberandthemicrocavity.Byconsideringthelargescatteringlossofoff-resonantlightfromthefiberwithinthecouplingregion,thisphenomenoncanbeattributedtopartiallyresonantlightbypassingthelossyscatteringregionviaWGmodes,allowingittobecoupledbothtoandfromthecavity,thenmanifestingasLorentzianpeakswithinthetransmissionspectra.Thisimpliesthesystemcouldbeimplementedwithinabandpassfilterframework.
简介:Thispaperinvestigatestheoreticallytheelectronictransmissionspectraofthethreeterminalpyrenemolecularbridgeandthequantumcurrentdistributiononeachbondbythetight-bindingmodelbasedonnonequilibriumGreen'sfunctionandthequantumcurrentdensityapproach,inwhichoneπmolecularorbitalistakenintoaccountpercarbonatomwhentheenergylevelsandHOMO-LUMOgapareobtained.Thetransmissionspectrashowthattheelectronictransmissionofthethreeterminalpyrenemolecularbridgedependsobviouslyontheincidentelectronicenergyandthepyreneeigenenergy.Thesymmetricalandoscillationpropertiesofthetransmissionspectraareillustrated.Anovelplus-minusenergyswitchingfunctionisfound.Thequantumcurrentdistributionshowsthattheloopcurrentsinsidethepyreneareinduced,andsomebondcurrentsaremuchlargerthantheinputandtheoutputcurrents.Thereasonswhytheloopcurrentsandthelargerbondcurrentsareinducedarethephasedifferenceoftheatomicorbitsandthedegeneracyofthemolecularorbits.ThecalculationsillustratethatthequantumcurrentdistributionsareingoodagreementwithKirchhoffquantumcurrentconservationlaw.
简介:Forapreviouslysimulatedeight-broadbandnegative-refraction-indexchiralmetamaterial,weuseS-parameterretrievalmethodstodeterminethecomplexeffectivepermittivity,permeability,andtheimpedance.Wealsocalculatethefigureofmerit,whichisdefinedastheratiooftherealandtheimaginaryrefractioncomponents,andcompareitwiththoseoffishnetmetamaterials.Thesimulationresultsshowthatourchiralmetamaterialexhibitshightransmissionandimpedancematchingtoavacuum.Also,wedeterminethattheelectricandmagneticdipolesofthesurfaceplasmonsplayanimportantroleindeterminingthenineresonancefrequencies.Therefore,thisinvestigationprovidesanexperimentalbasisfordevelopingmetamaterialdeviceswithmultipleandbroadresonancefrequencybands.
简介:Whenadielectricmeta-atomisplacedintoasubwavelengthmetallicaperture,20-foldenhancedelectromagnetictransmissionthroughtheapertureisrealizedatthemeta-atom’sresonantfrequency.Additionally,whentheincidentelectromagneticpowerincreases,thermalenergygatheredbythemeta-atom,whichisconvertedfromelectromagneticlosses,cancausethemeta-atom’stemperaturetoincrease.Becauseofthehightemperaturecoefficientofthemeta-atom’sresonantfrequency,thistemperatureincreasecausesablueshiftinthetransmissionpeak.Therefore,thisfrequency-dependentenhancedelectromagnetictransmissionevenproducesanonlineareffectatlowincidentpowers.Overanincidentpowerrangefrom0to20dBm,measuredandsimulatedspectranearthemeta-atom’sresonantfrequencyshowdistinctlynonlineartransmission.
简介:Wecomprehensivelycharacterizethetransmissionperformanceofm-aryquadratureamplitudemodulation(m-QAM)signalsthroughasiliconmicroringresonatorintheexperiment.Usingorthogonalfrequency-divisionmultiplexingbasedonoffsetQAM(OFDM/OQAM)whichismodulatedwithm-QAMmodulations,wedemonstratelow-penaltydatatransmissionofOFDM/OQAM64-QAM,128-QAM,256-QAM,and512-QAMsignalsinasiliconmicroringresonator.Theobservedopticalsignal-to-noiseratio(OSNR)penaltiesare1.7dBfor64-QAM,1.7dBfor128-QAM,and3.1dBfor256-QAMatabit-errorrate(BER)of2×10-3and3.3dBfor512-QAMataBERof2×10-2.Theperformancedegradationduetothewavelengthdetuningfromthemicroringresonanceisevaluated,showingawavelengthrangeof0.48nmwithBERbelow2×10-3.Moreover,wedemonstratedatatransmissionof191.2-Gbit/ssimultaneouseightwavelengthchannelOFDM/OQAM256-QAMsignalsinasiliconmicroringresonator,achievingOSNRpenaltieslessthan2dBataBERof2×10-2.
简介:Inrealmultiple-inputmultiple-output(MIMO)systems,theperfectchannelstateinformation(CSI)maybecostlyorimpossibletoacquire.Butthechannelstatisticalinformationcanbeconsideredrelativelystationaryduringlong-termtransmission.Thestatisticalinformationcanbeobtainedatthereceiverandfedbacktothetransmitteranddonotrequirefrequentupdate.Byexploitingchannelmeanandcovarianceinformationatthetransmittersimultaneously,thispaperinvestigatestheoptimaltrans-missionstrategyforspatiallycorrelatedMIMOchannels.Anupperboundofergodiccapacityisderivedandtakenastheper-formancecriterion.Simulationresultsarealsogiventoshowtheperformanceimprovementoftheoptimaltransmissionstrategy.
简介:Pump-probedifferentialreflectionandtransmissionspectroscopyisaveryeffectivetooltostudythenonequilibriumcarrierdynamicsofgraphene.Thereportedsignofdifferentialreflectionfromgrapheneisnotexplicitlyexplainedandnotconsistent.Here,westudythedifferentialreflectionandtransmissionsignalsofgrapheneonadielectricsubstrate.Theresultsrevealthesignofdifferentialreflectionchangeswiththeincidentdirectionoftheprobebeamwithrespecttothesubstrate.Theobtainedtheorycanbeappliedtopredictthedifferentialsignalsofothertwo-dimensionalmaterialsplacedonvariousdielectricsubstrates.
简介:Lattice,charge,orbital,andspinarethefourfundamentaldegreesoffreedomincondensedmatter,ofwhichtheinteractivecouplingderivestremendousnovelphysicalphenomena,suchashigh-temperaturesuperconductivity(high-T_cSC)andcolossalmagnetoresistance(CMR)instronglycorrelatedelectronicsystem.Directexperimentalobservationofthesefreedomsisessentialtounderstandingthestructure-propertyrelationshipandthephysicsbehindit,andalsoindispensablefordesigningnewmaterialsanddevices.Scanningtransmissionelectronmicroscopy(STEM)integratingmultipletechniquesofstructureimagingandspectrumanalysis,isacomprehensiveplatformforprovidingstructural,chemicalandelectronicinformationofmaterialswithahighspatialresolution.Benefitingfromthedevelopmentofaberrationcorrectors,STEMhastakenabigbreakthroughtowardssub-angstromresolutioninlastdecadeandalwaysstepsforwardtoimprovethecapabilityofmaterialcharacterization;manyimprovementshavebeenachievedinrecentyears,therebygivinganindepthinsightintomaterialresearch.Here,wepresentabriefreviewoftherecentadvancesofSTEMbysomerepresentativeexamplesofperovskitetransitionmetaloxides;atomic-scalemappingofferroelectricpolarization,octahedraldistortionsandrotations,valencestate,coordinationandspinorderingarepresented.WeexpectthatthisbriefintroductionaboutthecurrentcapabilityofSTEMcouldfacilitatetheunderstandingoftherelationshipbetweenfunctionalpropertiesandthesefundamentaldegreesoffreedomincomplexoxides.