简介:Awatt-classbackwardwaveoscillatorisproposed,usingtheconcisesinewaveguideslow-wavestructurecombinedwithapencilelectronbeamtooperateat220GHz.Firstly,thedispersioncurveofthesinewaveguideiscalculated,then,theoscillationfrequencyandoperatingvoltageofthedevicearepredictedandthecircuittransmissionlossiscalculated.Finally,theparticle-in-cellsimulationmethodisusedtoforecastitsradiationperformance.Theresultsshowthatthisnovelbackwardwaveoscillatorcanproduceover1-Wcontinuouswavepoweroutputinafrequencyrangefrom210GHzto230GHz.Therefore,itwillbeconsideredasaverypromisinghigh-powermillimeter-wavetoterahertz-waveradiationsource.
简介:Inthispaperweconsiderinfinitehorizonbackwarddoublystochasticdifferentialequations(BDSDEsforshort)coupledwithforwardstochasticdifferentialequations,whoseterminalfunctionsarenon-degenerate.ForsuchkindofBDSDEs,westudytheexistenceanduniquenessoftheirsolutionstakingvaluesinweightedL~p(dx)■L~2(dx)space(p≥2),andobtainthestationarypropertyforthesolutions.
简介:Combinedthedecompositionoftimereversaloperatorandthetimereversalre-verberationnulling,anewtimereversalprocessingapproachforecho-to-reverberationratioenhancementisproposed.Inthismethod,a2-dimensionalsignalsubspacefortherangeofthetargetandtwobottomfocusingweightvectorsfortherangesnearthetargetareobtainedbythedecompositionoftimereversaloperator.Fromthesignalsubspaceandfocusingweightvectors,aconstrainedoptimalexcitationweightvectorofsourcereceiverarraycanbededucedtonulltheacousticenergyonthecorrespondingbottomandmaximizetheenergyatthetar-get.Thismethodremediestheshortagesofconventionaltimereversalprocessing,timereversalreverberationnullingandtimereversalselectivefocusingmethod.Itfocusessoundenergyatthetargetandnullstheenergyatthebottomnearthetargetrangesimultaneously,thereforeenhancingtheecho-to-reverberationratiowithoutprobesourceandprior-knowledgeoftherel-ativescatteringintensityoftargetandbottom.Numericalsimulationsintypicalshallowwaterenvironmentsshowedtheeffectivenessoftheproposedmethodanditsimprovedperformanceforecho-reverberationenhancementthanconventionaltimereversalprocessing.
简介:Thispaperproposesahybridmethodbasedontheforward-backwardmethod(FBM)andthereciprocitytheorem(RT)forevaluatingthescatteringfieldfromdielectricroughsurfacewitha2Dtargetaboveit.Here,theequivalentelectric/magneticcurrentdensitiesontheroughsurfaceaswellasthescatteringfieldfromitarenumericallycalculatedbyFBM,andthescatteredfieldfromtheisolatedtargetisobtainedutilizingthemethodofmoments(MOM).Meanwhile,therescatteredcouplinginteractionsbetweenthetargetandthesurfaceareevaluatedemployingthecombinationofFBMandRT.OurhybridmethodisfirstvalidatedbyavailableMOMresults.Then,thefunctionaldependencesofbistaticandmonostaticscatteringfromthetargetaboveroughsurfaceuponthetargetaltitude,incidentandscatteringanglesarenumericallysimulatedanddiscussed.Thisstudypresentsanumericaldescriptionforthescatteringmechanismassociatedwithrescatteredcouplinginteractionsbetweenatargetandanunderlyingrandomlyroughsurface.