简介：ThispapergivesacharacterizationofaHuntprocesspathbythefirstexitleftlimitdistribution.Itisalsoshowedthatifthefirstexitleftlimitdistributionleavinganyballfromthecenterisauniformdistributiononthesphere,thentheL'evyProcessesareascaledBrownianmotion.

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简介：Spacetimetrelliscoding(STTC)techniqueshavebeenproposedtoachievebothdiversityandcodinggainsinmultipleinputmultipleoutput(MIMO)fadingchannels.ButwithmoretransmitantennasSTTCssufferfromthedesigndificultyandcomplexityincreasing.Thispaperproposesascheme,namedparallelconcatenatedspacetimetrelliscodes(PC-STTC),toachievethetradeoffbetweentheperformancesandcomplexityofSTTCsforalargenumberoftransmitantennas.Simulationresultsandcomplexitycomparisonareprovidedtodemonstratetheperformanceandsuperiorityoftheproposedschemeoverconventionalschemesinfastfadingchannelsinlowsignal-to-noiseratio(SNR)regions.AndanEXIT(extrinsicinformationtransform)chartisgiventoanalyzetheiterativeconvergenceoftheproposedscheme.ItshowsthatPC-STTChasbetteriterativeconvergenceinlowSNRregions.

简介：Fora〈r〈b,theapproachofLiandZhou（2014）isadoptedtofindjointLaplacetransformsofoccupationtimesoverintervals（a,r）and（r,b）foratimehomogeneousdiffusionprocessbeforeitfirstexitsfromeitheraorb.Theresultsareexpressedintermsofsolutionstothedifferentialequationsassociatedwiththediffusionsgenerator.Applyingtheseresults,weobtainmoreexplicitex-pressionsonthejointLaplacetransformsofoccupationtimesforBrownianmotionwithdrift,BrownianmotionwithalternatingdriftandskewBrownianmotion,respectively.

简介：LetLBbethelastexittimefromacompactsetBofanellipticdiffusionprocessX.AmoderateestimateforthedistributionofLBisobtained,andthesufficientandnecessaryconditionforEx(LBk)<∞isproved.

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简介：TheexitwavefunctionincludingzeroandhighorderLauezoneshasbeensimulatedbybothmulti-slicemethodandelectrondynamicdiffractionanalyticalexpression.Coincidenceofthesimulationsbythesetwomethodswasachieved.ThecalculatedresultsshowedthattheexitwavefunctionhighlydominatedbyzeroorderLauezone,whilehighorderonesmodifytheexitwavefunctiontosomeextentdependingonthesituation.HighorderLauezoneeffectsbecomeimportantforthefollowingcases:sampleconsistsoflightelements,thethicknessisverythin,latticeplanarspacingperpendiculartothedirectionoftheincidentbeamislarge,andtheelectronbeamhaslongwavelength.InthesecasestheexitwavefunctionshouldbecorrectedbyaddinghighorderLauezoneeffects.TheanalyticalexpressioniseffectiveandconvenientfordealingwithhighorderLauezoneeffects.

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简介：串行级联连续相位调制（SCCPM）系统可以大大地提高系统的功率利用率,这使得它在无线通信领域中得到广泛应用。给出了基于外信息传输（EXIT）图的SCCPM系统的收敛性能分析及外码设计,在CPM参数给定的情况下,通过EXIT图可以找出与该调制最匹配的外码。仿真结果表明：对于同一种调制不同外码的SCCPM系统,收敛的门限不同;收敛的门限越低,性能越好。

简介：Electron-wallinteractionisalwaysrecognizedasanimportantphysicalproblembecauseofitsremarkableinfluencesonthrusterdischargeandperformance.Basedonexistingtheories,anelectrodeispredictedtoweakenelectron-wallinteractionduetoitslowsecondaryelectronemissioncharacteristic.Inthispaper,theelectron-wallinteractioninanAton-typeHallthrusterwithlow-emissiveelectrodesplacedneartheexitofdischargechannelisstudiedbyafullykineticparticle-incellmethod.Theresultsshowthattheelectron-wallinteractionintheregionofsegmentedelectrodeisindeedweakened,butitissignificantlyenhancedintheremainingregionofdischargechannel.Itismainlycausedbyelectrodeconductivepropertywhichmakesequipotentiallinesconvextowardchannelexitandevenparalleltowallsurfaceinnear-wallregion;thisconvexequipotentialconfigurationresultsinsignificantphysicaleffectssuchasrepellingelectrons,whichcausestheelectronstomovetowardthechannelcenter,andtheelectronsemittedfromelectrodestoberemarkablyaccelerated,therebyincreasingelectrontemperatureinthedischargechannel,etc.Furthermore,theresultsalsoindicatethatthedischargecurrentinthesegmentedelectrodecaseislargerthaninthenon-segmentedelectrodecase,whichisqualitativelyinaccordancewithpreviousexperimentalresults.

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简介：Inthisarticle,thelowpressureaxialflowfanwithcircumferentialskewedrotorblade,includingtheradialblade,theforward-skewedbladeandthebackward-skewedblade,wasstudiedwithexperimentalmethods.Theaerodynamicperformanceoftherotorswasmeasured.Atthedesignconditionatoutletoftherotors,detailedflowmeasurementswereperformedwithafive-holeprobeandaHot-WireAnemometer(HWA).Theresultsshowthatcomparedtotheradialrotor,theforward-skewedrotordemonstratesawiderStableOperatingRange(SOR),isabletoreducethetotalpressurelossinthehubregionandmakemainloadingofbladeaccumulatinginthemid-spanregion.Thereisawiderwakeintheuppermid-spanregionoftheforward-skewedrotor.Comparedtotheradialrotor,inthebackward-skewedrotorthereishighertotalpressurelossnearthehubandshroudregionsandlowerlossinthemid-spanregion.Inaddition,thevelocitydeficitinthewakeisloweratmid-spanofthebackward-skewedrotorthantheforward-skewedrotor.