简介:Inthefiberopticalsyntheticaperture(FOSA)system,thediffractionoftheGaussianbeamlimitedbytheapertureinexitpupilplaneoffibercollimatorisstudiedtheoretically,andtheaxialandtransverseirradiancedistributionsareobtained.Thepointspreadfunction(PSF)andmodulationtransferfunction(MTF)ofthetruncatedGaussianbeamarrayarecomputednumericallywithdifferenttruncationfactors.TheresultsshowthatthediffractionofthetruncatedGaussianbeamarrayagreeswiththeuniform-beamRayleighdiffractionwhenthetruncationfactorislessthan0.5,butlittlepoweristransmitted.ThePSFandMTFaredegraded,butmorepowercanbecontainedwhenthetruncationfactorislarger.Theselectionofthetruncationfactorisatrade-offbetweenthelossoftransmissionandthequalitiesofPSFandMTFinpracticalapplication.
简介:Anovelactivecontourmodelisproposed,whichincorporateslocalinformationdistributionsinafuzzyenergyfunctiontoeffectivelydealwiththeintensityinhomogeneity.Moreover,theproposedmodelisconvexwithrespecttothevariablewhichisusedforextractingthecontour.Thismakesthemodelindependentontheinitialconditionandsuitableforanautomaticsegmentation.Furthermore,theenergyfunctionisminimizedinacomputationallyefficientwaybycalculatingthefuzzyenergyalterationsdirectly.Experimentsarecarriedouttoprovetheperformanceoftheproposedmodeloversomeexistingmethods.Theobtainedresultsconfirmtheefficiencyofthemethod.
简介:Nonlineardynamicalsystemsaresometimesundertheinfluenceofrandomfluctuations.Itisdesirabletoexaminepossiblebifurcationsforstochasticdynamicalsystemswhenaparametervaries.Acomputationalanalysisisconductedtoinvestigatebifurcationsofasimpledynamicalsystemundernon-Gaussianα-stableLévymotions,byexaminingthechangesinstationaryprobabilitydensityfunctionsforthesolutionorbitsofthisstochasticsystem.ThestationaryprobabilitydensityfunctionsareobtainedbysolvinganonlocalFokker-Planckequationnumerically.Thisallowsnumericallyinvestigatingphenomenologicalbifurcation,orP-bifurcation,forstochasticdifferentialequationswithnon-GaussianLévynoises.
简介:同学们在启动某个常用程序时,通常会依次单击“开始”→“程序”,然后找到需要启动的程序,再点击它,或者找到并双击桌面上的程序快捷图标来启动该程序。