简介：TheentanglemententropyofanacousticblackholeinaBose–Einsteincondensates(BEC)isderived,whichisassociatedwiththephononsgeneratedviatheHawkingmechanisminasonichole.ConsideringthedispersionrelationofaBEC,werecalculatetheentanglemententropyoftheacousticblackholebymeansofstatisticalmethodintwolimits.Wefindthattheentropyisstillproportionaltotheareaofeventhorizon,butwithacoefcientdependentontheinfraredcutof.

简介：Acousticfatiguelifeevaluationisessentialforthermalprotectionstructuresduetotheseverethermo-acousticloadinservice.AstudyontemperaturedependenceofacousticfatiguelifeforaC/SiCpanelispresentedinthispaper.EffectsoftemperatureonboththestructuralresponsesandtheS–Ncurvesareinvestigated.TheDirlikmethodisadoptedtopredictthefatiguelifeofaC/SiCpanelatthreedifferenttemperaturesrespectively.Significantdifferencesareobservedfromtheresultsofnumericalsimulationsbetweenthefatiguelivesofthepanelinthethreecases.Thetemperature-dependenceofacousticfatiguelifeofaC/SiCpanelisverified,andfatiguetestofthematerialneedstobemoreattentivelyperformed.

简介：四种SiO2(510nm)+Fe3O4(44.8m)粒子在一块唯一的声学的地，一个唯一的磁场和一块联合的声学磁性的地里被使流体化。一块单个场地，声学的100dB/4060Hz或10mT的介绍磁性，能压制插并且channeling和还原剂表面的最小的使液化气体速度，Umf。联合声学并且磁场表明了甚至更有希望的结果，特别Umf的更重要的减小。

简介：

简介：一个近似方法向前被带预言声学的压力基于表面velocity.It被称为方法(ERSM).The学习在声学的压力由在统一速度和其它表面元素颤动的相应表面元素散发了的声学的转移向量(ATV)平等者发现那个各个元素的元素放射重叠保留still.that声学的压力被相应困惑的pistonvibrating在统一velocity.So散发，它利用声学的压力radiat

简介：MechanicalqualityfactorQmisakeycharacteristicparameterofHigh-overtonebulkacousticresonator(HBAR).Theeffectsofstructureparameter(thickness)andperfor?manceparameters(characteristicimpedanceandmechanicalattenuationfactor)ofsubstrate,piezoelectricfilmandelectrodeconstitutingHBARonQmarecarriedout.TherelationshipsbetweenQmandtheseparametersareobtainedbyalumpedparameterequivalentcircuitinsteadofdistributedparameterequivalentcircuitneartheresonancefrequency,andthean?alyticalexpressionsoiQmaregiven.TheresultsshowthatQmincreasesnon-monotonicallywiththecontinuousincreaseofthesubstratethicknessforHBARwithcertainpiezoelectricfilmthickness,anditapproachestothesubstratematerialmechanicalqualityfactorasthesubstratethicknessislarge.QmdecreaseswavilywiththecontinuousincreaseofthepiezoelectricfilmthicknessforHBARwithcertainsubstratethickness.SapphireandYAGwithlowmechanicallossareappropriateasthesubstratetogetalargerQm-TheelectrodelossmustbeconsideredsinceitcanreduceQm-ComparedwithAuelectrode,A1electrodewithlowerlosscanobtainhigherQmwhentheappropriateelectrodethicknessisselected.Inaddition,Qmdecreaseswiththeincreaseoffrequency.TheseresultsprovidethetheoreticalbasisforoptimizingtheparametersofHBARandshowthattrade-oflFsbetweenQmandmustbeconsideredinthedesignbecausetheirchangesareofteninconsistent.

简介：在水下的声学的散布回应时间空间组织并且及时是aliasing并且频率领域。当事件角度是未知的时，回响性质的不同系列没被识别。这篇文章在monostatic声纳的目标回响调查变化处理这个问题。有类似的结构的母亲小浪用匹配的过滤器，和在延期因素之间的理论表达式根据预处理信号波形被建议了，事件角度在小浪域被导出。在这个方法能有效地分开几何散布的免费地的水池表演的模拟数据和试验性的结果的分析目标回响的部件。在一个单个角度从几何回响获得的时间延期评价与一致指向几何特征，没有角度信息，它为目标识别提供一个基础。调查结果为分析在实际海洋环境散布回响的橡皮提供珍贵卓见。

简介：作为结构的材料，靠近房间的铝泡沫与开的房间铝泡沫相比在产品尺寸，力量和过程经济拥有明显的优点。作为一种结构功能集成材料，靠近房间的铝泡沫的申请由于声波穿入的困难在声学的领域里极大地被限制了。有宏观结构的靠近房间的泡沫在声波的繁殖上有重要效果，这被报导。迄今为止，在宏观结构之间的关系和商业地纯的靠近房间的铝泡沫的声学的性质是模糊的。在这个工作，不同穿孔和空气差距类型为改变泡沫的宏观结构被设计。同时，健全吸收系数和健全减小索引上的宏观结构的效果被调查。结果证明有一半洞的泡沫在高频率范围展出了优秀健全吸收和健全屏蔽行为(>2500?Hz)。另外，没有空气差距，有空气差距的标本与泡沫相比在低频率显示出好健全吸收性质。基于实验结果，繁殖在有不同宏观结构的商业地纯的靠近房间的铝泡沫的声波的结构的模型被造，声学的性质上的宏观结构的影响被讨论。

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

简介：Absorptionofacousticnanowaveinspecificfrequencyregionisimportantforthedesignofacousticfilter.Thispaperputsforwardametamaterialmodelmadeupoffluid-conveyingcarbonnanotubes(CNT),whichcanabsorbacousticnanowaveinagivenfrequencyrangebyadjustingthelengthsandfluidvelocitiesofthemselves.Absorptioncoefficientsarecalculatedoutthroughthecombinationofthefiniteelementmethodwiththetheoreticalmodel,whichare0.4~0.55relatingtodifferentfluidvelocitiesforthecrossing-distributedmodel.Comparisonsaremadebetweenthecrossedmodelandthealignedone,whichprovethattheCNTforestwithcrosseddistributionismoreeffectiveinacousticwaveabsorption.

简介：当常规时近地的声学的雷射摄影术不技术是健全的地由调制信号导致了的appliedto，modulating频率不能被重建的结果揭示。解决这个问题，一不，为调制健全来源的分析方法论被建议。第一，Hilbert变换被介绍使解调信号，然后modulating部件被重建由不技术。数字模拟和实验结果证明精确重建分析能被建议方法获得。

简介：Currentstudiesareaimingatmonitoringcorrosiondamageofaircraftmainstructuresbyusingacousticemission(AE)techniqueandatsupplyingusefuldatafordeterminingcalendarlifeoftheaircraft.ThecharacteristicsofAEsignalsproducedduringacceleratingcorrosionprocessaredescribed,andmethodsforevaluatingcorrosiondamagesanddeterminingremaininglifeofmainstructuresofaircraftusingAEtestingareoutlined.ExperimentalresultshaveshownthatAEtechniquecandetectcorrosiondamageofaluminumalloymuchearlierthanconventionalnon-destructivetestingmeans,suchasultrasonictestingandeddycurrenttesting.RelationshipbetweencorrosiondamageandAEparameterswasobtainedthroughinvestigatingcorrosiondamageextentandchangesofAEsignalsduringacceleratingcorrosiontest,andshowingthatAEtechniquecanbeusedtodetectearlycorrosion,investigatingcorrosiondevelopingtrend,andinmonitoringandevaluatingcorrosiondamages.

简介：Cyclostationary健全的地是nonstationary声音地，压力信号严重在被调制的一种特殊类型，边带在它的光谱存在。重建的健全的地不能在常规Nearfield声学的雷射摄影术考虑cyclostationary特征(不)过程。根据平面cyclostationary不，cyclostationary不基于边界元素方法被建议它能被利用与复杂表面分析散热器。用秒顺序代替Fourier的变换周期的统计，周期光谱密度(CSD)功能被用作重建的物理数量在不建议了技术，而不是光谱或力量光谱压力的密度信号。由CSD功能的解调能力的优点，重建的CSD能有效地分别地表示modulating和搬运人波浪的信息。模拟和实验说明这cyclostationary的有效性和精确性不技术满足工程的请求。

简介：Noncoherentunderwateracousticcommunicationchannelinadverseconditionsismodeledasaphase-randomRayleighfadingchannel,anditscapacitycurveisderived.Toapproachthechannelcapacitycurve,theconcatenatedcodeofthenonbinaryLDPCcodeandtheconstantweightcodeisproposedfornoncoherentcommunicationwhichcanlatebeiterativelydecodedintheprobabilitydomain.Withoutinformationofchannelamplitudeorphaseinthereceiver,statisticparametersoftherespectivesignalandnoisebinswereestimatedbasedonthemomentestimationmethod,theposteriorprobabilitiesoftheconstantweightcodewordswerefurthercalculated,andthenonbinaryLDPCcodewasdecodedwiththenonbinaryfactorgraphalgorithm.Itisverifiedbysimulationsthatbyutilizingtheproposedconcatenatedcodeanditsprocessingalgorithm,gaptochannelcapacitycurveisreducedby3dBwhencomparedtotheexistingmethod.Underwatercommunicationexperimentswerecarriedoutinbothdeepocean(verticalcommunication,5km)andshallowlake(horizontalcommunication,near3km,delayspreadlargerthan50ms),inwhichthesignalfrequencybandwas6kHzto10kHz,andthedatatransmissionrateWas357bps.Theproposedschemecanworkproperlyinbothexperimentswithasignal-to-noiseratiothresholdof2dB.TheperformanceoftheproposedalgorithmWaswellverifiedbytheexperiments.

简介：

简介：Inthispaper,theone-dimensional(1D)particle-in-cell(PIC)simulationisusedtostudythemodulationinstabilityofionacousticwavesinelectron–ionplasmas.TheionacousticwaveisdescribedbyusinganonlinearSchr¨odingerequation(NLSE)derivedfromthereductiveperturbationmethod.Formournumericalsimulations,weareabletodemonstratethat,afterthemodulation,theamplitudeincreasessteadilyovertime.Furthermore,bycomparingthenumericalresultswithtraditionalanalyticalsolutions,weacquiretheapplicationscopeforthereductiveperturbationmethodtoobtaintheNLSE.Wealsofindthismethodcanalsobeextendedtootherfieldssuchasfluiddynamics,nonlinearoptics,solidstatephysics,andtheBose–Einsteincondensatetovalidatetheapplicationscopeoftheresultsfromthetraditionalperturbationmethod.

简介：

简介：Therearesomecurvedinterfacesinoceanacousticwaveguides.Tocomputewavepropagationalongtherangewithsomemarchingmethods,aflatteningoftheinternalinterfacesandatransformingequationareneeded.Inthispaperalocalor-thogonalcoordinatetransformandanequationtransformationareconstructedtoflatteninterfacesandchangetheHelmholtzequationasasolvableform.Forawaveguidewithaflattop,aflatbottomandncurvedinterfaces,thecoefficientsofthetrans-formedHelmholtzequationaregiveninaclosedformulationwhichcanbethoughtofasanextensionoftheformalworkrelatedtotheequationtransformationwithtwocurvedinternalinterfaces.Inthetransformedhorizontallystratifiedwaveguide,theone-wayreformulationbasedontheDirichlet-to-Neumann(DtN)mapisthenusedtoreducetheboundaryvalueproblemtoaninitialvalueproblem.NumericalimplementationoftheresultingoperatorRiccatiequationusesalargerangestepmethodtodiscretizetherangevariableandatruncatedlocaleigenfunctionexpansiontoapproximatetheoperators.Thismethodisparticularlyusefulforsolvinglongrangewavepropagationproblemsinslowlyvaryingwaveguides.Furthermore,themethodcanalsobeappliedtowavepropagationproblemsinacousticwaveguidesassociatedwithvarieddensity.

简介：在测量完全的声学的地向量性质任何一个或在周围的噪音精力流动和相对地指导的流动之间的部分取消，例如，放射了能由音调或塑造噪音的点来源是在那里的大小写无关紧要的found.In兴趣的协调或支离破碎的地interact.The现象被称为反对精力fluxes.The纸的赔偿集中于在表面噪音精力流动和反映底部的塑造噪音的int的垂直部件之间的相互作用

简介：