简介:Inthispaper,wedemonstratetheacetylehe(C2H2)sensorwithhighsensitivityusingahollow-corephotonicbandgapfiber(HC-PCF).ExperimentsformeasuringC2H2concentrationsingasmixtureareperformed.Usinga2m-longHC-PCFasgascell,thespectrumofacetyleneatn1+n3bandhasbeenmeasured,andtheP11-branchhasbeenselectedforthepurposeofsensing.Aminimumdetectivityof143partspermillionbyvolume(ppmv)forthesystemconfigurationisestimated.
简介:Themixedl1/H2optimizationproblemforMIMO(multipleinput-multipleoutput)discrete-timesystemsisconsidered.Thisproblemisformulatedasminimizingthel1-normofaclosed-looptransfermatrixwhilemaintainingtheH2-normofanotherclosed-looptransfermatrixatprescribedlevel.ThecontinuitypropertyoftheoptimalvalueinrespecttochangesintheH2-normconstraintisstudied.Theexistenceoftheoptimalsolutionsofmixedll/H2problemisproved.Becausethesolutionofthemixedl1/H2problemisbasedonthescaled-Qmethod,itavoidsthezerointerpolationdifficulties.Theconvergentupperandlowerboundscanbeobtainedbysolvingasequenceoffinitedimensionalnonlinearprogrammingforwhichmanyefficientnumericaloptimizationalgorithmsexist.
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:UsingdoublecrystalX-raysdiffraction(DCXRD)andatomicforcemicroscopy(AFM),theresultsofGexSi1-xgrownUHV/CVDfromSi2H6andSiH4areanalyzedandcompared.Adsorbatescanmigratetotheenergy-favoringpositionduetotheslowgrowthratefromSiH4.Inthiscase,aSibufferthatisolatestheeffectofsubstrateonepilayercouldnotbegrown,whichresultsinapitpenetratingintoepilayerandbuffer.TheFWHMis0.055°inDCXRDfromSiH4.Thepresenceofdiffractionfringesisanindicationofanexcellentcrystallinequality,TheroughnessofthesurfaceisimprovedifgrownbySi2H6:however,thecrystalqualityoftheGex2Si1-xmaterialbecameworsethanthatfromSiH4duetomuchlargergrowthratefromSi2H6.ThecontentofGeisobtainedfromDCXRD,whichindicatesthegrowthratefromSi2H6islargest,thenGeH4andthatfromSiH4isleast.
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.