简介：声学的散布从一沉没由一个事件飞机波浪的充满液体的有限的圆柱的壳insonified被学习。散布领域的分析答案与边界条件用有弹性的薄壳理论被导出。由于内部液体的效果，充满液体的阻抗必须增加系统的阻抗。结果证明在backscattering地里，僵硬散布仅仅在舷侧和有弹性的散布玩上有大贡献一个主要角色什么时候倾斜的发生。阶段速度的分散曲线显示出那与内部真空条件作比较，除了由纵的波浪的贡献并且砍舷侧附近的波浪一系列内部液体引起的另外的波浪被增加它有大贡献到散布领域。碗--形状回声曲线作为内部液体波浪的贡献在频率角度光谱被介绍。

简介：ARevisedEditionofthenow-classical1971texteditedbyL.Beranek,NoiseandVibrationControl,hasbeenpublishedbytheInstituteofNoiseControlEngineering.NoiseandVibrationControlisofgreatvaluetodesignandsafetyengineers,consultants,scientists,architects,governmentresearchers,publicofficialsandothersconcernedwiththecontrolofnoiseemittedbymachineryandwithcontrolofenvironmentalnoiseinbuildings,intheworkplace,nearairportsandhighways,andinthecommunity.This

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简介：ThestatisticalpropertiesofthemodeconvertedSVwavespecklesinthebackscatteringspacewerestudiedasultrasonicPwaveswereincidentonastronglyscatteringinterface.BasedontheFrensel-Huygenstheoryandthecorrelationprinciple,theRayleighdistributionoftheSVwavespeckleamplitudeandtheformulaforcalculatingtheaveragelateralsizeoftheSVwavespeckleswereobtained.Besides,theprobabilitydensityfunctionofthenormalizedintensityoftheSVwavespecklesreceivedbyatransversewaveprobewithanapertureofsomesizewasdeduced.Theprobabilitydensityfunctionwasrelatedtotheaveragenumberofthespecklesreceivedbytheprobe.TwotransversewaveprobeswithaperturesindifferentsizewereemployedtomeasurethesoundintensityoftheSVwavespecklesintheexperiment.Aftertheexperimentaldataofthespeckleintensitywereanalyzedstatistically,itwasshownthattheexperimentalresultswereingoodagreementwiththetheoreticalones.Thus,thepresentedtheoreticalconclusionswereprovedtobecorrect.

简介：ProfessorBeranektalkedaboutthesoundqualitiesofconcerthall.The58famousconcerthallsintheworldweregradedaccordingtothesubjectivecomparisonfromtheprofessionalmusiciansandmusiclovers.Sixmeasurableobjectiveparameterswereproposed.Therankingaccordingtotheseparameterswerepresented.

简介：Thisstudyperformsthequantitativeanalysisandcomparisontoacousticsignalcharact,eristicsofLargcyellowcroaker(Pseudosciaenacrocea)attwodifferentages.Thesoundswercrecordedfromthefishesinanet-cage.Twoexponentialoscillationfunctionsarebuilttofittheacousticsignalofthefishes.Thesignalcharacteristicoftheoscillationfrequencyandattcnuationcoefficientwasdescribedquantitatively.Simulationcurvesofthefunctioncouldfitwellacousticsignals.Boththeaverageoscillationfrequencyandattenuationcoefficientofthefittedsignalsfromthe13-15-month-oldfishesarclowerthanthosefromthe7-8-month-oldfishes.Theresultssuggestthattheoscillationfrequencyandattenuationcoefficientoftheacollsi.icsignalfunctionmayberelevanttothephysicalproccssofsoundproductionandagecharacteristicsofLargeyellowcroaker.Thisstudymaybevaluablefortheacousticapplicationtotheartificialcultureofthespecies.

简介：AmethodtoidentifycomplexYoung’smodulusofviscoelasticmaterialsusingforcedlongitudinalvibrationofslenderrodsisproposed.Themethoddiffersfromthebeamone.Experimentaltestswerecarriedoutatroomtemperaturewithdifferentlengthsin108mm,100mm,90mm,83.5mm,80mm.74.5mm,70mmforthepolycarbonatebars,andthecurvesofratiosA2/A1betweentwoendsofaviscoelasticbarversusfrequenciesareobtained,furthermore,thecorresponding3dBbandwidthandthestorageandlossmoduluscanbecalculated.SufficientnumberofobtainedcomplexYoung’smodulusatdifferentfrequencyallowsustocalculateotheronesusingtheleastsquaremethod.Ifthestepofthetestedfrequencyis5Hz,themaximumerrorofresultscanbelessthan6%.Bycomparisonwiththemeasurementmethodswhichthepreviousliteraturementioned,thisnewmethodsimplifiesthecalculation,andthephysicalmeaningappearsapparentlyandclearly.

简介：基于液体动力学，热转移和声学的结果，一个计算液体动力学(CFD)方法被利用在一根Rijke管子内学习声学的特征和自我刺激的跳动机制。为了避免解决有限振幅的站的荒谬的边界条件，在Rijkethermo声学的系统飘动，在流动领域里当模特儿的模拟，它联合了有它的外层空间的管子内部，被执行代替传统的方法处于良好的竟技状态内部流动地数字调查。为在包括在热来源，摆动压力和摆动速度附近的空气的不稳定的热上的关系的精力方程的热来源的一个假设被介绍。为了反映Rijke的本质，尖叫，自我刺激的摆动上的模拟借助于它压力，速度和温度的自己的跳动被进行。这个方法能使集中过程稳定并且有效地避免分叉。自我刺激的Rijke管子的物理现象被分析。而且，Rijke管子的自我刺激的摆动上的机制是这个方法上的explained.Based，关于有不同尺寸和嘴的不同形状的Rijke管子的声学的特征的比较研究被执行。模拟结果令人满意地同意了试验性的数据。结果证明这数字模拟能被用来为Rijke管子的设计申请学习嘴的健全压力。