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

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

简介：Simpleandefficientsurfaceacousticwave(SAW)two-portresonatorswithlowinsertionlossandhighQ-valuesonST-Xquartzsubstrateusingacorrosion-proofA1/Au-stripeelectrodestructurearedevelopedforgassensing.Itwascomposedoftwoshortedgratingreflectorsandadjacentintedigitaltransducers(IDT),andanactivemetalfilminthecavitybetweentheIDTsforthesensitivefilmcoating.Thedevicesareexpectedtoprovidegoodprotectiontowardsmetalelectrodeforgassensorsapplicationinchemicallyreactiveenvironments.Excellentdeviceperformanceaslowinsertionloss,highQfactorandsingle-modeareachievedbycarefullyselectingthemetallicelectrodethickness,cavitylengthandacousticaperture.Priortofabrication,thecouplingofmodes(COM)modelwasperformedfordevicesimulationtodeterminetheoptimaldesignparameters.Thefabricatedsingle-modeSAWresonatoratoperationfrequencyof300MHzrangeexhibitsmatchedinsertionlossof~6.5dBandloadedQfactorinthe3000range.Usingthefabricatedresonatorasthefeedbackelement,adualresonator-oscillatorwithexcellentfrequencystability(0.1ppm)wasdevelopedandevaluatedexperimentally,anditissignificantforperformanceimprovementofSAWgassensor.