简介:Themixedl1/H2optimizationproblemforMIMO(multipleinput-multipleoutput)discrete-timesystemsisconsidered.Thisproblemisformulatedasminimizingthel1-normofaclosed-looptransfermatrixwhilemaintainingtheH2-normofanotherclosed-looptransfermatrixatprescribedlevel.ThecontinuitypropertyoftheoptimalvalueinrespecttochangesintheH2-normconstraintisstudied.Theexistenceoftheoptimalsolutionsofmixedll/H2problemisproved.Becausethesolutionofthemixedl1/H2problemisbasedonthescaled-Qmethod,itavoidsthezerointerpolationdifficulties.Theconvergentupperandlowerboundscanbeobtainedbysolvingasequenceoffinitedimensionalnonlinearprogrammingforwhichmanyefficientnumericaloptimizationalgorithmsexist.
简介:目前上海局动车段CRH2动车组三级修进入量产化阶段,经过为期三年多的CRH2型动车组三级修,流水化检修流程已经有了较好的优化,工艺也做了多方面的改进。转向架的检修质量是保证动车组平稳、安全运行的基础,分析转向架检修过程中的关键工序和重要项点对提高转向架检修质量,确保动车组的安全、可靠具有非常重要的意义。尤其随着高铁的快速发展,动车配属量扩大,动车组走行公里数也普遍增长,动车检修的质量更要加强,检修效率更要提高。本文主要针对CRH2型车在三级修检修过程中的流程和工艺重要项点进行梳理,提出作业过程中关键工序卡控项点,对以后CRH2型车三级修向更高标准、更高检修效率和更好发展有着十分重要的意义。
简介:Inthispaper,wedemonstratetheacetylehe(C2H2)sensorwithhighsensitivityusingahollow-corephotonicbandgapfiber(HC-PCF).ExperimentsformeasuringC2H2concentrationsingasmixtureareperformed.Usinga2m-longHC-PCFasgascell,thespectrumofacetyleneatn1+n3bandhasbeenmeasured,andtheP11-branchhasbeenselectedforthepurposeofsensing.Aminimumdetectivityof143partspermillionbyvolume(ppmv)forthesystemconfigurationisestimated.
简介:[1]CaoYY,LamsJ.RobustH∞ControlofUncertainMarkovianJumpSystemswithTime-Delay.IEEETrans.Automat.Contr.,2000,45(1):77~83.[2]DoyleJC,Glover,KhargonekarPP,etal.State-SpaceSolutionstoStandardH2andH∞ControlProblems.IEEETrans.Automat.Contr.,1989,34(8):831~847.[3]FridmanE,ShakedU.H∞-normandInvariantManifoldsofSystemswithStateDelays.Sys.&Contr.Lett.,1999,36(2):157~165.[4]GeJ,FrankPM,LinCF.RobustH∞StateFeedbackControlforLinearSystemswithStateDelayandParameterUncertainty.Automatica,1996,32(6):1183~1185.[5]HirataM,LiuKZ,SatoT,etal.ASolvabilityConditionofanExtendedH∞ControlProblemUsingRiccatiInequalities.Int.J.Contr.,2000,73(4):265~275.[6]HmamedA.FurtherResultsontheRobustStabilityofUncertainTime-DelaySystems.Int.J.Syst.Sci.,1991,22(3):605~619.[7]IwasakiT,Skelton,E.AllControllersfortheGeneralH∞ControlProblem:LMIExistingConditionsandState-SpaceFormulas.Automatica,1994,42(7):1307~1317.[8]LeeB,LeeJG.RobustStabilizationofLinearDelayedSystemswithStructuredUncertainty.Automatica,1999,35(6):1149~1154.[9]LeeKH,MoonYS,KwonWH.RobustStabilityAnalysisofParametricUncertainTime-DelaySystems.InProceedingofIEEEConferenceonDecisionandControl,Tampa,FL,1998:1346~1352.[10]LehmanB,KhalilS.DelayIndependentStabilityConditionsandDecayEstimatesforTime-VaryingFunctional.IEEETrans.Automat.Contr.,1994,39(8):1673~1676.[11]MahmoudMS,Al-MuthairiNF.DesignofRobustControllersforTime-DelaySystems.IEEETrans.Automat.Contr.,1994,39(2):159~161.[12]MoriETN,KuwaharaM.AwaytoStabilizeLinearSystemswithDelayedState.Automatica,1983,19(5):571~573.[13]NiculescuSI,andAnnasuamyAM.ASimpleAdaptiveControllerforPositive-RealSystemswithTime-Delay.ProceedingoftheAmericanControlConference,Chicago,Illi
简介:Anultrahighvacuumchemicalvapordeposition(UHV/CVD)systemisintroduced.SiGealloysandSiGe/Simultiplequantumwells(MQWs)havebeengrownbycold-wallUHV/CVDusingdisilane(Si2H6)andgermane(GeH4)asthereactantgasesonSi(100)substrates.ThegrowthrateandGecontentsinSiGealloysarestudiedatdifferenttemperatureanddifferentgasflow.ThegrowthrateofSiGealloyisdecreasedwiththeincreaseofGeH4flowathightemperature.X-raydiffractionmeasurementshowsthatSiGe/SiMQWshavegoodcrystallinity,sharpinterfaceanduniformity.Nodislocationisfoundintheobservationoftransmissionelectronmicroscopy(TEM)ofSiGe/SiMQWs.TheaveragedeviationofthethicknessandthefractionofGeinsingleSiGealloysampleare3.31%and2.01%,respectively.
简介:HandoverinDigitalVideoBroadcastingforHandhelds(DVB-H)aimstoprovidecontinuousmobilebroadcastingserviceswhenauseristravelingthroughcellboundaries.Agoodhandovercontrolcanimprovethepowerefficiencyandgainmuchbetterreceptionquality.ThisletterprovidesanovelapproachforDVB-HhandoverbasedonDVB-H/UniversalMobileTelecommunicationsSystem(UMTS)hybridnetwork,whichmovesthemainhandoverfunctionfromtheterminalstothenetworks,sothatitreducestheoperationcomplexityoftheterminalsandincreasesthepowersaving.WhentheterminalcannotreceivetheDVB-Hsignalinthetransmissionshadowareasorbecauseofsomeotherreasons,theUMTSnetworksmayofferthesameservicetouserstomaketheservicecontinuous.AstheUMTSnetworkshavethetopologyoftheDVB-Hnetworks,bycommunicatingwiththeterminals,theUMTSnetworkscanhelptheterminalstopredictthehandover,andavoidunnecessaryhandover.
简介:Thea-Si∶H/SiNx∶HsampleseriesareinvestigatedbymeansofRamanscatteringtechnique(RST).Theresultshowsthatduetothestructuralmismatchbetweena-Si∶Handa-SiNx∶H,severeinduceddistortionsareproducedintheinterfaceoftheheterojunction,andtheseinduceddistortionstendtowardsacertainenergystate.Theorderingoftheinterfacestructuredependsontheperiodicnumberofmultilayerthinfilms.
简介:Theproblemoftherobustfaultdetectionfilterdesignfortime-varyingdelaysswitchedsystemsisconsideredintheframeworkofmixedH_-/H_∞.Firstly,theweightedH_∞performanceindexisutilizedastherobustnessperformance,andtheH_-indexisusedasthesensitivityperformanceforobtainingtherobustfaultdetectionfilter.ThenanovelmultipleLyapunov-Krasovskiifunctionisproposedforderivingsufficientexistenceconditionsoftherobustfaultdetectionfilterbasedontheaveragedwelltimetechnique.Byintroducingslackmatrixvariable,thecouplingbetweentheLyapunovmatrixandsystemmatrixisremoved,andtheconservatismofresultsisreduced.Basedontherobustfaultdetectionfilter,residualisgeneratedandevaluatedfordetectingfaults.Inaddition,theresultsofthispaperaredependentontimedelays,andrepresentedintheformoflinearmatrixinequalities.Finally,thesimulationexampleverifiestheeffectivenessoftheproposedmethod.
简介:ThispaperintroducestwostepstodesignaquantizerofH.261CODEC:thefirststepistoimplementthecoarsequantizingthroughcontrolalgorithmforthebuffer'soccupationratio;thesecondstepistofinishtheaccuratequantizingthroughthecontrolalgorithmofvisualcharacteristics.Moreover,satisfactoryeffectsaregotusingthesealgorithmsthroughexperiment.
简介:TherobustH∞controlfornetworkedcontrolsystemswithbothstochasticnetwork-induceddelayanddatapacketdropoutisstudied.Whendataaretransmittedovernetwork,thestochasticdatapacketdropoutprocesscanbedescribedbyatwo-stateMarkovchain.Thenetworkedcontrolsystemswithstochasticnetwork-induceddelayanddatapacketdropoutaremodeledasadiscretetimeMarkovjumplinearsystemwithtwooperationmodes.ThesuffcientconditionofrobustH∞controlfornetworkedcontrolsystemsstabilizedbystatefeedbackcontrollerispresentedintermsoflinearmatrixinequality.Thestatefeedbackcontrollercanbeconstructedviathesolutionofasetoflinearmatrixinequalities.Anexampleisgiventoverifytheeffectivenessofthemethodproposed.
简介:Aconductionchannelmodelispropsedtoexplainthehighconductivitypropertyofnc-Si:H.Detailedenergybanddiagramisdevelopedbasedontheanalysisandcalculation,andtheconductivityofthenc-Si:Hwasthenanalysedonthebasisofenergybandtheory.Itisassumedthattheconductivityofthenc-Si:Hstemsfromtwoparts:theconductanceoftheinterface,wherethetransportmechanismisidentifiedasathermal-assistedtunnelingprocess,andtheconductancealongthechannelaroundthegrain,whichmainlydeterminedthehighconductivityofthenc-Si:H.Theconductivityofnc-Si:Hiscalculatedandcomparedwiththeexperimentdata.Thetheoryisinagreementwiththeexperiment.
简介:UsingdoublecrystalX-raysdiffraction(DCXRD)andatomicforcemicroscopy(AFM),theresultsofGexSi1-xgrownUHV/CVDfromSi2H6andSiH4areanalyzedandcompared.Adsorbatescanmigratetotheenergy-favoringpositionduetotheslowgrowthratefromSiH4.Inthiscase,aSibufferthatisolatestheeffectofsubstrateonepilayercouldnotbegrown,whichresultsinapitpenetratingintoepilayerandbuffer.TheFWHMis0.055°inDCXRDfromSiH4.Thepresenceofdiffractionfringesisanindicationofanexcellentcrystallinequality,TheroughnessofthesurfaceisimprovedifgrownbySi2H6:however,thecrystalqualityoftheGex2Si1-xmaterialbecameworsethanthatfromSiH4duetomuchlargergrowthratefromSi2H6.ThecontentofGeisobtainedfromDCXRD,whichindicatesthegrowthratefromSi2H6islargest,thenGeH4andthatfromSiH4isleast.
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简介:本文着重研究了H.265编码的高清视频质量评价方法,以用于未来测试H.265编码器的性能。根据ITUVQEG的最新研究进展,介绍了高清视频的主观评价和客观测量方法,并且分析了目前已有的客观测量技术的主要实现方法和与主观评价方法相关度的结果,最后给出H.265编码视频质量测量技术的发展建议,并指出针对H.265编码器的测试,实验室环境,全参考的方法是首选,而无参考的方法是研究趋势。
简介:Ananalysisisgiventoexplaintheinstabilityofthehighconductivitypropertyofnc-Si:Hfabricated.Detaileddiscussioniscarriedoutconcentratingontheconductivityandgrowthmechanism.Itisassumedthattheinstabilityoftheconductivityofthenc-Si:Hstemsfromtwopart:thephasetransitionfromnanocrystallitesintoa-Si:H,andtheoxygenincorporationofthethinlayerofthefilm,whichcontributesmoretotheeffectwhenthefilmsufferstheexposuretoair.Thetheoryisinagreementwiththeexperimentandmeasurement.
简介:ThisletterproposesaratecontrolalgorithmforH.264videoencoder,whichisbasedonblockactivityandbufferstate.ExperimentalresultsindicatethatithasanexcellentperformancebyprovidingmuchaccuratebitrateandbettercodingefficiencycomparedwithH.264.ThecomputationalcomplexityofthealgorithmisreducedbyadoptinganovelblockactivitydescriptionmethodusingtheSumofAbsoluteDifference(SAD)of16×16mode,anditsrobustnessisenhancedbyintroducingafeedbackcircuitatframelayer.