简介：

简介：Inthispaper,theangularspreadoftheSAWbeamdiffractedbyBragggrating,denotedbyδθ1,isana-lysedbasedontheequationsofthedeflectionangleandthedeflectioneffciency.AparameterδθBisde-finedtoreferto"Braggangularspectrumwidth"ofthegrating.Theimportanceofthisparameterindis-tinguishingtheangularspreadrangeofthedeflectedbeamfordifferentregimesisdiscussedaswell.Itisshowfromtheanalysisthatifthespreadangleoftheincidentbeamlabelledwithδθincislargethanthe"Braggwitdthoftheangularspectrum"ofthegrating,thespreadangleδθ1ofthedeflectedbeamwillequaltoδθB;butiftheangulardivergenceoftheincidentbeamislessthanδθB,thenδθ1=δθincExperimentally,fourkindsofsampleswithdifferentconfigurationsareinvestigatedbyopticalmethod,twoofwhichoperateintheregimeofδθinc<<δθBandtheotherscorrespondtothecaseintheregimeofδθinc>>δθB.Thewidthsoftheangularspreadoftheinciden

简介：Inthispaper,abeam-platecoupledstructureisdiscussed.Thederivationofexactexpressionsforpowertransferandnumericalcomputa-tionarecarriedon.ItisfoundthattheSEAtechniquesmaybeappropri-ateforstrongcoupledstructuresandthatthegeneralSEAresultprovidesgoodagreementwiththeexactcalculationwhenmodaloverlapishigh.Thederivedformulaisappliedtopredictthecouplinglossfactorandvibrationalenergyofsubstructures.Theagreementbetweentheestimatedandmeasuredresultspresentsquitewellinmostcases.

简介：Thegeometricaltheoryofdiffraction(GTD),combinedwithFouriertransformation,hasbeenappliedtotheback-scatteringonafinite-lengthrigidcircularcylinderduetoanarrowsoundbeam.Thetheoreti-calresultsareconfirmedbythemodelexperiment.

简介：一个nonparaxialmulti-Gaussian横梁模型基于矩形的孔被建议以便克服在离开轴横梁的输的精确性回答的paraxialGaussian横梁模型的hmitation。与方法，一个超声的线性分阶段执行的数组变换器产生的听觉的地被计算并且由Rayleigh-Sommerfeld积分，paraxialmulti-Gaussian横梁模型，和Fraunhof-fer近似方法与相应的域相比获得了。模拟例子证明那个nonparaxialmulti-Gaussian横梁模型由paraxial近似条件是不有限的并且能高效地并且精确地预言听觉的地在大量驾驶角度上由一个线性分阶段执行的数组变换器放射了。

简介：Thelowfrequencylinecomponentsoftheradiatednoisefromanunderwatertargetusuallyhavebothhighspectrumlevelandsustainedstability.Thisfeaturecouldbeusedtoincreasethedetectionperformanceofconventionalbroadbandenergyintegrationmethod.Therequiredspectrumlevelistheoreticallydiscussedwhenthedetectionperformanceoftheknownlinedetectionisbetterthanthatofbroadbandenergyintegrationmethod.Undertheconditionofthetargetcanbedetectedinlinespectrumband,therelationshipbetweenthelinespectrumlevelandsignaltonoiseratio(SNR)isalsodiscussed.ThispaperproposesalinespectrumtargetdetectionmethodthatamatrixusingDCjumptofluctuationsratiosofsub-bandspatialspectrumandbeamspaceoutputisconstructed.Thismatrixactsasafilterthatthelinespectrumtargetwithcertainfrequencyandazimuthispassedatmost.Byfusingwiththeothersubbandresults,theconventionaldetectionperformancecanbeimproved.Atthesametime,theapplicableconditionanddetectionperformanceareanalyzedinthepaper.Thesimulationandtheseatrialdataprocessingresultsshowthatthealgorithmcaneffectivelyextractweakgoallinespectrumtargetundertheconditionofmulti-interference.Thealgorithmdoesn’tneedmulti-framestatisticsandthedetectionperformanceisclosertotheoptimallinespectrummethod.