简介：Thefar-fieldnoiseradiatedfrommixinglayersisdeterminedbythenear-fieldflowdynamicswhichissensitivetotheinitialperturbationofinstabilityintroducedphysicallyornumerically.Thisstudyfocusesontheeffectsofthephasedelayintwoinitialperturbations,oneatthefundamentalwavenumberandtheotheratitssubharmonicbothcalculatedfromlinearinstabilityanalysis,onthesoundgenerationinmixinglayers.Whendifferentphasedelaysφ_1changingfromzeroto2πisappliedonthefundamentalmode,weobservedifferentvortexmergingprocesses(e.g.vortexpairingortearing).Thestrongnonlinearinteractioninthemergingprocessgeneratesmostofthenoisefrommixinglayers.Thereshowsapatterninaperiodof2πfortheresponseoffar-fieldsoundtothechangeofφ_1.Similareffectsonthedynamicsandacousticscanbeachievedbyaddingdifferentphasedelaysφ_2tothesubharmonicmodeinstead,however,theresponserepeatsinaperiodofonlyπforφ_2.Theeffectsofthecombinationofdifferentphasedelaystootherparameters,includingtheamplitudeandwavenumberforeachperturbations,arealsoinvestigated.Alltheresultsindicateacriticalroleofnonlinearityinthesoundgenerationmechanismofmixinglayers.

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简介：Manystudieshaveexploredtheimportanceandinfluenceofplanetaryboundarylayerprocessesontropicalcyclones(TCs).However,fewstudieshavefocusedontheinfluenceoflandsurfaceprocessesontheactivityofTCs.TotesttheeffectofinitialperturbationsoflandsurfaceprocessesonTCs,alandsurfaceprocessperturbationmoduleisbuiltinaglobalensemblepredictionsystem.EnsembleexperimentsfortheTCsthatoccurredfrom12UTC22Augustto18UTC24November,2006showthatconsiderationoftheuncertaintieswithinthelandsurfaceprocesscouldincreasethepredictabilityoftheglobalensemblepredictionsystem.DetailedanalysisonTCXangsane(2006)indicatesthattheperturbationoflandsurfaceprocessesmayincreasethevariationofsensibleheatfluxandlatentheatflux.Meanwhile,theeffectfromlandsurfaceperturbationcanbetransferredtotheupperatmosphere,whichleadstobetterTCforecasts.

简介：在这篇文章的调查的基本目标是非线性的冲动的微分方程。冲动的时刻与所谓的障碍曲线的不可分的曲线和一些相遇的片刻与一致。为方程的如此的类型，足够的条件在答案在哪个下面连续地依赖于关于起始的条件和障碍曲线的不安下面被发现。结果被用于人口动力学的一个数学模型。