简介：Therearesomebasicproblemsinprevioustheoreticalstudiesofbaroclinicinstability.Thederivedcriticalbaroclinitywasconsiderablylowerthanthetimeaveragedmeanmeridionaltemperaturegradient,especiallyinthelowertroposphere.Also,thelinearmechanismofbaroclinicdisturbancedevelopmentwhichisnotedrestrictedbythecriticalbaroclinitywasnotstudiedsufficiently.Therealisticcriticalbaroclinityanddisturbancedevelopmentarediscussedinthisstudy.Itwillbeshownthatthecriticalconditionofinstabilityandtypicaltimeandspacescalesofdisturbancesde-pendonthree-dimensionalstructuresofatmosphereandsphericityoftheearth,otherthanthehorizontaltemperaturegradientalone.Thevariantbehaviourofatmosphericdisturbancesdependshighlyontheirspecificscalesthatmaybedescribedbythesametheoreticalmodel.Thus,therewouldbenosubstantialdifferencesinthebasicinstabilitymecha-nismofmanydisturbancesincludingthepolarlowsandexplosivecyclones.

简介：Thepurposeofthispaperistostudythedynamicalmechanismoferrorgrowthinthenumericalweatherprediction.Theerrorisdefinedinthesenseofgeneralizedenergy,simplycalledenergyerror.Fromthespectralformoftheprimi-tiveequations,wehavederivedtheevolutionequationsoferrorindetail.Theanalysesoftheseequationshaveshownthattheerrorgrowthrateisdeterminedbythetangentlinearequations.Thenonlinearadvectioncausedbytheerrorperturbationitselfcontributesnothingtotheerrorgrowthrate,andonlyredistributestheerror.Furthermore,anap-proachtocalculationoftheerrorgrowthratehasbeendeveloped,whichcanalsobeusedtostudythelocalinstabilityoftime-independentbasicstateaswellastime-dependencebasicstate.Thisapproachisappliedtowell-knownLorenz’ssystem,andtheresultsareindicativeofthecorrectnessandsignificanceofthetheoreticalanalyses.

简介：1.GeneralReviewTherapiddevelopmentofextrahighvoltagetransmissionlinesandpowersystemsraisedseriousstabilityproblems.Becauseofthelongdistancetransmissionofpowerandrelativeweaksystemconfiguration,stabilitybecamethemostimportantandseriousproblems.Therisksintermsofdisturbancecausingsubsequentsysteminstabilitycouldbeveryhighandtheresultsoffrequencyandvoltagecollapsemaycausecatastrophicresults.

简介：Problemsofinstabilityofrotatingatmosphericmotionsareinvestigatedbyusingnonlineargoverningequationsandthevariationalprinciple.Themethodsuggestedinthispaperisuniversalforobtainingcriteriaofinstabilityinallmodelswithallpossiblebasicflows.Forexample,themodelcanbebarotropicorbaroclinic,layerorcontinuous,quasi-geostrophicorprimitiveequations;thebasicflowcanbezonalornonzonal,steadyorunsteady.Althoughthebasicflowspossessagreatdealofvariety,theyallarethestationarypointsinthefunctionalspacedeterminedbyanappropriateinvariantfunctional.Thebasicflowisanunsteadyoneiftheconservationofangularmomentumisincludedintheassociatedfunctional.Thesecondvariation,linearornonlinear,givesthecriteriaofinstability.Especially,thegeneralcriteriaofinstabilityforunsteadybasicflow,orographicallydisturbedflowaswellasnongeostrophicflowarefirstobtainedbythemethoddescribedinthispaper.Itisalsosh

简介：柱体hydrogel在几何学简单并且容易综合，广泛地因此被用来调查hydrogel的胀大/缩小的不稳定性，许多不稳定性模式在文学被积累。不过，这种唯一的配置的不稳定性模式形成的机制充分远离是被理解。我们使用了并且延长，并且执行了抑制柱体hydrogel的胀大导致稳定性的线性不安分析聚合物胶化的最近发达的非线性的理论进圆柱的坐标。我们导出压力和联系平衡方程的增长明确的表达。我们为不稳定性的发作获得了批评条件并且在hydrogel的稳定性图上在细节探查了各种各样的参数的效果。稳定性图的变化的物理意思也被解释。

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简介：Inthisarticletheemphasiswasgiventothediscussionoftheeffectsofdiameterratioandswirlingoninstabilitycharacterforthegas/liquidcoaxialjetusedbyLiao,etal.[1].Theresultsindicatethatthefinitediameterratiomarkedlyincreasesthemaximumgrowthrate,themostunstablewavenumber,aswellasthecutoffwavenumber.Itimpliesthatthefinitediameterratiowillleadtotheliquidjetbreakuplengthshorterandtheliquiddropsizesmaller.Theeffectoftheswirlingjetsismuchmorecomplex:fortheaxisymmetricperturbationmode,theswirlingenhancestheflowstability,forhelicalperturbation,thedominantinstabilitymodeoccursatn<0.Anditisfoundthatinlongwaveregionthereexistsanewkindofinstabilitymodesatn=1thatwasnotmentionedinLiaoetal.'sarticle.Forthisnewmode,thereappearsadominatedswirlingratioatwhichtheflowhasthemaximumgrowthrate.

简介：Startingfromnonlinearequationsonthef-planecontainingfrictionaldissipationundertheBoussinesqapproximation,anewkindofgeneralizedenergyisproposedastheLyapunovfunction,andaveragesaretakenasanyfunctionsof(x,z)insteadofthecommonly-usedmeansofbilinearfunctionsof(x,z),therebyresultinginanewcriterionofgeneralizednonlinearsymmetricstability.Itshowsthatnotonlymustthedissipativecoefficientbegreaterthanacertaincriticalvaluebuttheinitialdisturbanceamplitudemustbesynchronouslysmallerthananothermarginalvalueaswell.Itfollowsthatthelatterimposesacrucialconstraintontheformer,thusleadingtothefactthatwhentheamplitudeisbiggercomparedtoanothercriticalvalue,generalizednonlinearsubcriticalsymmetricalinstabilitymayoccur.Thenewcriterioncontributesgreatlytotheimprovementofthepreviousresultsofitskind.

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简介：岩石块的排水量和岩石结构的性质在隧道的稳定性起一个重要作用。基于关键块模型，受到集中的短时间的有压缩性的波浪的地下的隧道的动态不稳定性分析被进行。分裂和惯性的效果引起的隧道的不稳定性被区分。并且隧道的房顶轮廓弯曲的影响也被决定。

简介：Thephysicalmechanismforgenerationofstreamwisevortices(orribvortices)inthecylinderwakeisnumericallyinvestigatedwithafinite-differencescheme.Rayleigh’stheoryofcentrifugalinstabilityforinviscidaxisymmetricflowisextendedtoanalyzethe2-Dprimaryflows.Accordingly,ananalyticaldimensionlessgroupRay=-(r/vθ)■vθ/■r-1isderived,wherevθrepresentsthevelocityofafluidelementrelativetotheoncomingflow,risthelocalcurvatureradiusoftheelementpathline.CentrifugalinstabilityoccurswhenRay>0.StabilityanalysesarecarriedoutwiththisdiscriminantforprimaryflowsatdifferenttimelevelsinahalfsheddingperiodofthevonKarman(orvK)vortices.UnstableareasareidentifiedandthelocationsofribvorticesarecoincidentwellwiththeunstableareaswithinthefirstwavelengthofvKvorticesbehindthecylinder.Thenumericalresultsalsoshowthatribvorticesexperienceamplificationinthisregion.Itisapparentthatcentrifugalinstabilityplaysanimportantroleinthegenerationofribvorticesinthecylinderwake.

简介：这研究介绍一个新方法识别敏感区域，它由为台风调用潮湿的潜在的涡度(MPV)的否定异例是坚定的适应观察。否定MPV的区域是对称的不稳定性区域并且能为台风作为敏感区域被拿，这被发现适应观察。在2008的三台风，Nuri，Fung-wong，和Fengshen，在MM5的帮助下被模仿模型。这些台风很好在开始的12个小时被模仿，这被显示出。把调查基于这些，MPV的计算顺序被执行。结果证明MPV的否定最大值总是绕为所有盒子的台风眼睛，它意味着敏感区域总是也在他们附近。

简介：Inthispaper,weinvestigateaclassofHamiltoniansystemsarisinginnonlinearcompositemedia.Bydetailedanalysisandcomputationweobtainadecayingestimatesonthesemigroupandprovetheorbitalinstabilityoftwofamiliesofexplicitsolitarywavesolutions(slowfamilyinanisotropiccaseandsolitarywavesinisotropiccase),whichtheoreticallyverifytherelatedguessandnumericalresults.

简介：学习shear不稳定性的传统的Kelvin-Helmholtz观点不对与联系的盒子合适砍有大风的线在旋涡表砍。从那以后，shear不稳定性成为旋涡表的theinstability。如果速度被旋涡表导致，不平等(1？Rr+Rid)>0并且U(v，t)>U((t))成为旋涡表不稳定性的标准。这个标准显示那1)环境地的布置制止沿着shear线发展的骚乱。2)在那里多存在在shear的不稳定的过程的鈥攕c淡色啤酒相互作用排队。为不稳定性的必要条件的计算也在这篇论文被介绍。关键词砍线-导致的速度-旋涡表的不稳定性这个工作被工程在严重MesoscaleCovective的动态学习上在资助G1998040907下面并且由关键工程在中国在构词的机制和重要气候和天气灾难的预兆的理论的学习上支持系统在资助No.49735180下面由中国的国家自然科学基金会赞助了。

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简介：Hydrodynamicinstabilityandthemechanismsforturbulenceonsetandself-sustainingaretworesearchquestionsthathavepuzzledthescientistsforoveracentury,yetrenewedinterestandsignificantprogressoccurredinthelastdecadeorso.WeknowonlyfewexactanalyticalsolutionsoftheNavier-Stokesequations,theequationsgoverningtheflowofsimplefluidslikewaterandair,andmostoftheseareneverobservedinapplicationsorlaboratory

简介：TheevolutionofG?rtlervorticesanditsinteractionwithotherinstabilitiesareinvestigatedinthispaper.BoththeMackmodeandtheG?rtlermodeexistinhypersonicboundary-layerflowsoverconcavesurfaces,andtheirinteractionsarecruciallyimportantinboundarylayertransition.WecarryoutadirectnumericalsimulationtoexploretheinteractionbetweentheG?rtlerandtheobliqueMackmode.TheresultsindicatethattheinteractionbetweentheforcedG?rtlermodeandtheobliqueMackmodepromotestheonsetofthetransition.TheforcedobliqueMackmodeissusceptibletononlinearinteraction.BecauseofthedevelopmentoftheG?rtlermode,theforcedMackmodeandotherharmonicmodesareexcited.

简介：Honjiinstabilityandringingofoffshorestructruresaretwodifferentphenomena.Honjiinstabilityoccursatacircularcylinderintransverseperiodicfinitemotioninawatertank.Itissuperposedonthestreamingflowinducedbythecylinder'sboundarylayer.Itsoscillationperiodishalfoftheperiodofthecylinderoscillation.FinitevolumecalculationsofthefilteredNavier-Stokesequationsvisualizethethree-dimensionalinstability,wherefluidparticlestransportedbythecircumferencialrol...

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简介：Detailedanalysisofthelowfrequencyinstabilityisperformedinalinearmagnetizedsteadystateplasmadevice.Identificationandmodificationoftheinstabilityarepresented.