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

简介：Anewapproachtothetheoryoffinite-amplitudestandingwavesinproposed,andfoumulasofsteadywaveformsarederivedfromthefundamentalequationsofhydrodynamios,asanendeavortosettlethelong-timedisputablesituation.

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简介：从充满水的圆柱的壳散布领域的形成被学习。散布领域的分析解决方案用有弹性的薄壳理论和Sommerfeld-Watson转变SWT方法被导出。环绕的波浪的波浪数字杆数字地被发现的建筑群，阶段速度和在空圆柱的壳和充满水的圆柱的壳的状况之间的环绕的波浪的变细被比较。是镜子的思考部件和环绕的波浪的和的backscattering表格功能的合成与正常模式结果一致。环绕的波浪与试验性的结果相比的另外的液体的计算回响序列。更富有的回声山峰出现在充满水的圆柱的壳和回响结构的形成的backscattering表格功能的结果表演由于另外的液体的再放射效果是环绕的波浪。

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简介：Nonlinearacousticpropagationgeneratedbyapistoninafinitehornisnumericallystudied.Aquasi-one-dimensionalnonlinearmodelwithvaryingcross-sectionuseshigh-orderlow-dispersionnumericalschemestosolvethegoverningequation.Becauseofthenonlinearwavedistortionandreflectedsoundwavesatthemouth,broadbandtime-domainimpedanceboundaryconditionsareemployed.Theimpedanceapproximationcanbeoptimizedtoidentifythecomplex-conjugatepole-residuepairsoftheimpedancefunctions,whichcanbecalculatedbyfastandefficientrecursiveconvolution.Thenumericalresultsagreeverywellwithexperimentaldatainthesituationsofweaknonlinearwavepropagationinanexponentialhorn,itisshownthatthemodelcandescribethebroadbandcharacteristicscausedbynonlineardistortion.Moreover,finite-amplitudeacousticpropagationintypesofhornsissimulated,includinghyperbolic,conical,exponentialandsinusoidalhorns.Itisfoundthatsoundpressurelevelsatthehornmoutharestronglyaffectedbythehornprofiles,thedrivingvelocityandfrequencyofthepiston.Thepaperalsodiscussestheinfluenceofthehorngeometryonnonlinearwaveformdistortion.

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

简介：Thepropagationofmultipolemodalwavesalongthewell-axisinafluid-filledboreholesurroundedbyelasticandnonelastic,infiniteandfiniteformationisanalysedbyusingthewaveequations.Thephasevelocitydispersionandtheexcitationcurvesarenumericallycalculated.Thewaveformsexcitedbyattenuatingburstsarealsocalculated.Themeasurementswithlong-spaceddipoletransducersmadeofPZTthindisksvibratinginbendingmodearecarriedoutinaconcretemodelwellandtheexperimentalresultsarecomparedwiththetheoreticalresults.

简介：Usingultrasonicguidedwavestoassesslongbonefracturesandfracturehealinghasbecomeapromisingdiagnosticissue.Butthemultimodeoverlapoftheguidedwaveschallengesthequantitativeevaluationandclinicalapplication.Inthepreformedstudy,inordertosimplifythesignalinterpretation,thelow-frequencysinusoidialsignalswereusedtoonlyexciteS0andA0modesinfracturedlongbones.TheamplitudesofS0andA0modeswerenumericallyanalyzedwithvariationincrackwidthandfractureangle.Numericalsimulation,basedonthetwo-dimensionfinite-differencetime-domain(2D-FDTD)revealsthatbothS0andA0amplitudesdecreasewiththefracturewidening.However,theincreaseinfractureanglegraduallyenhancestheA0amplitude,whilewithrespecttotheS0mode,itsamplitudeshowsanon-monotonictrendtothevariationinfractureanglewithaturningpointaround45°.TheamplituderatiobetweenS0andA0canreflectthevariationsincrackwidthandfractureangles.ThesimulationillustratesthatultrasonicguidedS0andA0modesaresensitivetothedegreeofbothverticalandobliquefracturesinthelongcorticalbone.Thesefindingsmaybehelpfulforfracturesdiagnosisandhealingevaluationofthelongbone.

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简介：Anumericalmethodofsolvingacousticwavescatteringpnbleminfluidsisdescribed.Radiationboundarycondition(RBC)obtainedbyfactorizationmethodofHelmholtzequationisappliedtotransformingtheexteriorboundaryvalueprobleminunboundedregionintooneinafiniteregion.CombinedwithRBCandscatterersurfaceboundarycondition,Helmholtzequationissolvednumericallybythefinitedifferencemethod.ComputationalresultsforsphereandprolatespheroidalscatterersareinexcellentagreementwitheigenfunctionsolutionsandmuchbetterthantheresultsofOSRCmethod.

简介：浅水里的matchedfield处理的时间的关联(MFP)上的线性、独居的内部波浪的效果数字地与不同频率为声学的来源被调查，深度基于从experiment.It的海洋学的数据被显示出MFP的时间的关联作为独居的内部波浪的振幅减少或线性内部波浪increases.For的平均精力密度有更低的频率的声学的来源或下面定位了thermocline，tempor

简介：Duringsolareclipse,thelunarshadowmovesthroughtheearth‘satmospherewithsupersonicspeed.ChimonasandHinesdeemedthattheshockwavesproducedbycoolingofatmospherewouldinducegravitywaves,andbothTIDsandatmosphericpressurechangescanbedetectedintheionosphereandonthegroundrespectively.AlthoughtheIGWsignalsfromsolareclipseareusuallyquiteweak,theycanstillbedetected.Thepressurechangesongroundleveloccurneartheregionofeclipse,butcanbedetectedevenfarbeyondthepathofeclipse.ThisarticleisthefirstonetoreportresultsofdetectingpressurewavescausedbysolareclipseinChina.Druingthe23rdSeptember1987annularsolareclipse,IGWshavebeendetectedandrecordedatinfrasoundobservatoriesin(?)r(?)mqi,Taiyuan,XuzhouandSuzhou,whicharesituatedwithinthepathofannulareclipse,aswellasinBeijingandGuiyang,whicharesituatedontheoppositesidesofthispath.Thesignalsaredetectedbymicrobarometersofcondensermicrophonetype.Afteran

简介：把陈和Hau的理论基于D.P，一个理论方法被介绍分析嘘类型表面的分散特征与一个变化原则和coupling-of-modes在周期的金属性的栅栏结构上宣传的声学的波浪(锯)方程。没有使用复杂格林的功能，方法的精明的结果Hashimoto的理论与那些同意很好。在另一方面，Hashimoto的方法为在ST-90上计算short-circuited栅栏的分散关系是无助的

简介：在坚硬地在任意的角度连接的二个无限的盘子的角落接口的颤动精力传播被波浪途径学习以便调查堵住使用减少把波浪传播弄弯的飞机的质量的效果。二个本地坐标系统被介绍，暗示管理盘子的典型阻抗或堵住质量的相应比率的六个新非维的系数被介绍简化传播和思考系数的明确的表达。五件样品在experiment.Discussions被测试以插入损失基于在预言和实验之间的比较被执行。在角落接口堵住质量象“一个lowpass过滤器”一样行动，这被结束，为在某些频率上面的颤动变细有效。在“变细乐队”的TL和IL的价值每每统一一些堵住的团在惯性的集体时刻统一“变细乐队”的长度和乐队宽度主要取决于质量。

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