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简介：ThereflectionandtransmissionofLambwavesatoverlapjointsareresearchedbythenumericalmethodandtheexperiments.ThenumericalmethodisusedtosimulatethereflectionandtransmissionofLambwavesatweldswithdifferentwidthson2mm-thickstainlesssteelplates.Thereflectionandtransmissioncoefficientsarecalculatedaswell.Whentheweldswidthislessthan4mm,aquasi-linearcorrelationisobservedbetweenthereflectioncoefficientofSOmodeandtheweldwidth.Incontrasttotheweldwidth,boththegapbetweentwoplatesandthereinforcementheightofwelddonothaveobviouseffectonthereflectioncoefficient.Basedontheresults,weproposethattheweldwidthcouldberapidlymeasuredthroughexaminingtheechoamplitudeofSOmode.Experimentsfurtherconfirmthequasilinearcorrelationandthefeasibilityofourproposedmethod.

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简介：Thedispersioncharacteristicsandexcitationmechanismsoftheguidedwavesinmultilayeredplatesarestudiedinthispaper.Firstly,thedispersionequationisobtainedbythepropagatormatrixmethod.Then,thebisectiontechniqueisemployedtofindalltherootsofthedispersionequation.Thedispersioncharacteristicsoftheguidedwavesareinvestigatedandanalyzed.ForthemultilayeredplatesinwhichtheS-wavevelocityincreasesordecreasesfromtoptobottom,itisfoundthatthevelocitylimitsinhighfrequencyofthefirstandhighmodesareequaltotheRayleighwaveandS-wavevelocitiesofthelow-velocitylayer,respectively.ItisalsofoundthatthevelocitylimitsinthehighfrequencyofallmodesareequaltotheS-wavevelocityofthelow-velocitylayerfortheplatewithalow-velocitymiddlelayer.Thenormaldisplacementspectrumofallthemodesexcitedbythenormalforcesourcewithadefinitewidthonthesurfaceoftheplateisalsoinvestigated.ItisprovedthatthedominantmodeisthefirstmodewhentheS-wavevelocityincreasesfromtoptobottomlayerandthedominantmodeisdifferentindifferentfrequencyrangefortheplatewithalow-velocitymiddlelayer.

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简介：Wepresentsecond-orderexpressionsforthefree-surfaceelevation,velocitypotentialandpressureresultingfromtheinteractionofsurfacewavesinwaterofarbitrarydepth.Whenthesurfacewaveshavenearlyequalfrequenciesandnearlyoppositedirections,asecond-orderpressurecanbefeltallthewaytotheseabottom.Thereareatleasttwoareasofapplications:reflectivestructuresandmicroseisms.Microseismsgeneratedbywaterwavesintheoceanaresmallvibrationsofthegroundresultingfrompressureoscillationsassociatedwiththecouplingofoceansurfacegravitywavesandtheseafloor.Theyarerecordedonland-basedseismicstationsthroughouttheworldandtheyaredividedintoprimaryandsecondarytypes,asafunctionofspectralcontent.Secondarymicroseismsaregeneratedbytheinteractionofsurfacewaveswithnearlyequalfrequenciesandnearlyoppositedirections.Theefficiencyofmicroseismgenerationthusdependsinpartonoceanwavefrequencyanddirection.Basedonthesecond-orderexpressionsforthedynamicpressure,asimpletheoreticalanalysisthatquantifiesthedegreeofnearnessinamplitude,frequency,andincidenceangle,whichmustbereachedtoobservethephenomenon,ispresented.

简介：轮船的Ince-Strutt稳定性图表在不规则的波浪的参量的转动回声在不规则的波浪为参量的转动回声的探索被进行并且利用。参量的转动回声将导致的轮船大振幅转动运动甚至失事。第一，在不规则的波浪描述参量的转动回声的方程根据Grims有效理论被导出，相应Ince-Strutt稳定性图表被获得。第二，为在不规则、常规的波浪的参量的转动回声的稳定性图表的差别被比较。第三，波浪阶段和高峰时期被考虑获得一个更现实主义的海条件。当分析的点在不稳定性边界附近被定位时，随机的波浪阶段的影响应该被考虑。为不同波浪高峰时期的稳定性图表是各种各样的。稳定性图表对在设计舞台的参数决心有用更好适应驾驶状况。最后，轮船变量被一条统计途径根据稳定性图表分析。metacentric高度的增加将帮助改进轮船稳定性。

简介：由地志的特征散布飞机嘘波浪在一分层横着各向同性(TI)一半空间被使用一个间接边界元素方法(IBEM)调查。第一，反飞机分层的TI一半空间的动态僵硬矩阵被建立，免费的地被使用直接僵硬方法解决。然后，草地函数为在分层的TI一半空间对一根使倾向的线起作用的一致地分布式的负担被导出，散布的地与推出的草地函数被构造。最后，免费的地被加到散布的获得全球动态回答。方法被把结果与出版的各向同性的作比较验证。两个都，不变、短暂的动态回答被评估并且讨论。在频率领域的数字结果证明为TI媒介的表面运动能与为各向同性的案例的那些显著地不同，它强烈依赖于anisotropy性质，事件角度和事件频率。在时间领域的结果证明材料anisotropy在最大的持续时间和时间历史的最大的振幅上有重要效果。

简介：Nonlinearinteractionsofthetwo-dimensional(2D)secondmodewithobliquemodesarestudiednumericallyinaMach6.0flat-plateboundarylayer,focusingonitsselectiveenhancementeffectonamplificationofdifferentobliquewaves.Evolutionofobliquemodeswithvariousfrequenciesandspanwisewavenumbersinthepresenceof2Dsecondmodeissimulatedsuccessively,usingamodifiedparabolizedstabilityequation(PSE)method,whichisabletosimulateinteractionoftwomodeswithdifferentfrequenciesefficiently.Numericalresultsshowthatobliquemodesinabroadbandoffrequenciesandspanwisewavenumberscanbeenhancedbythefiniteamplitude2Dsecondmodeinstabilitywave.Theenhancementeffectisaccomplishedbyinteractionofthe2Dsecondmode,theobliquemode,andaforcedmodewithdifferencefrequency.Twotypesofobliquemodesarefoundtobemoreamplified,i.e.,obliquemodeswithfrequencyclosetothatofthe2Dsecondmodeandlow-frequencyfirstmodeobliquewaves.Eachofthemmaycorrespondtoonetypeoftransitionroutesfoundintransitionexperiments.Thespanwisewavenumberoftheobliquewavepreferredbythenonlinearinteractionisalsodeterminedbynumericalsimulations.

简介：Strongnonlinear,electro-optical,andthermo-opticalpropertiesoflithiumniobate（LN）havegainedmuchattention.However,theimplementationofLiNbO3inrealdevicesisnotatrivialtaskduetodifficultiesinmanufacturingandhandlingthin-filmLN.Inthisstudy,weinvestigateanopticaldevicewheretheBlochsurfacewave（BSW）propagatesonthethin-filmLNtounlockitsproperties.First,accesstotheLNfilmfromair（oropenspace）isimportanttoexploititsproperties.Second,forsustainingtheBSW,one-dimensionalphotoniccrystal（1DPhC）isnecessarytobefabricatedunderthethin-filmLN.Weconsidertwomaterialplatformstorealizesuchadevice:bulkLNandcommercialthin-filmLN.Clearreflectancedipsobservedinfar-fieldmeasurementsdemonstratethepropagationofBSWsontopoftheLNsurfaceofthedesigned1DPhCs.

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简介：Ameshlessradialbasisfunction(RBF)collocationmethodbasedontheEringennonlocalelasticitytheoryisdevelopedtocalculatethebandstructuresofternaryandquaternarynanoscalemulti-layeredphononiccrystals(PNCs)withfunctionallygraded(FG)interlayers.Detailedcalculationsareperformedforanti-planetransversewavespropagatinginsuchPNCs.TheinfluencesofFGandhomogeneousinterlayers,componentnumber,nonlocalinterfaceimperfectionsandnanoscalesizeoncut-offfrequencyandbandstructuresareinvestigatedindetail.Numericalresultsshowthatthesefactorshavesignificanteffectsonbandstructuresatthemacroscopicandmicroscopicscales.