简介:Usingtheextremedifferenceofself-similarityandkurtosisatlargelevelscaleofwavelettransformapproximationbetweenthePTFM(PulseTrainsofFrequencyModulated)signalsanditsreverberation,afeature-basedmatchedfiltermethodusingtheclassify-before-detectparagriamisproposedtoimprovethedetectionperformanceinreverberationandmultipathenvironments.Processingthedataoflake-trailsshowedthattheprocessinggainoftheproposedmethodisbiggerthanthatofmatchedfilterabout10dB.Inmultipathenvironments,detectionperformanceofmatchedfilterbecomebadlypoorer,whilethatoftheproposedmethodisimprovedbetter.Itshowsthatthemethodismuchmorerobustwiththeeffectofmultipath.
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简介:Geoacoustic倒置为声学的域预言是重要的并且在浅水里匹配域本地化。梳火柴地倒置MFI和Reflectionloss倒置,多步为geoacoustic参数的贝叶斯的倒置被介绍。这个方法为随后的倒置作为优先的信息从一倒置使用了以后的概率密度PPD或倒置结果。首先,敏感参数被MFI决定。第二,感觉迟钝的参数被思考损失倒置基于PPD决定,倒置源于MFI。PPD结果比直接火柴地倒置,和一些参数的倒置结果显著地被改进的显示多步倒置方法更好被执行。为了在声音上表明多步倒置方法的优点,回答预言,传播损失的统计性质基于以后的概率被介绍。传播损失分发证明预言的声学的地基于多步倒置方法有更小的错误。
简介:Thedispersioncharacteristicsandexcitationmechanismsoftheguidedwavesinmultilayeredplatesarestudiedinthispaper.Firstly,thedispersionequationisobtainedbythepropagatormatrixmethod.Then,thebisectiontechniqueisemployedtofindalltherootsofthedispersionequation.Thedispersioncharacteristicsoftheguidedwavesareinvestigatedandanalyzed.ForthemultilayeredplatesinwhichtheS-wavevelocityincreasesordecreasesfromtoptobottom,itisfoundthatthevelocitylimitsinhighfrequencyofthefirstandhighmodesareequaltotheRayleighwaveandS-wavevelocitiesofthelow-velocitylayer,respectively.ItisalsofoundthatthevelocitylimitsinthehighfrequencyofallmodesareequaltotheS-wavevelocityofthelow-velocitylayerfortheplatewithalow-velocitymiddlelayer.Thenormaldisplacementspectrumofallthemodesexcitedbythenormalforcesourcewithadefinitewidthonthesurfaceoftheplateisalsoinvestigated.ItisprovedthatthedominantmodeisthefirstmodewhentheS-wavevelocityincreasesfromtoptobottomlayerandthedominantmodeisdifferentindifferentfrequencyrangefortheplatewithalow-velocitymiddlelayer.
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简介:拿估计到达的方向被介绍的进报道的在数组元素之中的相互的联合的一个multi-subarraysubspace试穿方法。一致线性数组的相互的联合矩阵与banded被建模对称的Toeplitz矩阵。根据相互的联合矩阵的DOF(自由的度),在二个方面的数组元素的部分被忽视。精神算法的理论特征,适合算法的subspace之一,被学习。为大N和一致线性数组,MCLS精神评价错误是asymptotically,联合,与零个工具散布的Gaussian,和它的协变性表达式被获得。它从模拟被知道在那里存在当当它的变化有一些增加时,相互的联合不存在时,有为数组元素和信号来源的某些数字的最低评价错误的subarray,和它估计到达的方向的性能接近理想的状况。方法与高分辨率被用于深测术的sidescan声纳,并且好结果被获得了。以增加数组元素的数字的成本,方法能减少在数组元素之中的相互的联合的爱。
简介:直接模拟蒙特卡罗(DSMC)方法被介绍在多部件气体混合物为声学的繁殖建模。并且声学的变细的一个理论预兆的模型被建议,它不依靠经验的参数。各种各样的多部件气体混合物的声学的变细系列,由氮,氧,二氧化碳,甲烷和水组成,被DSMC方法估计。兴趣的健全频率范围从8MHz到232MHz。与基于DL,加古典变细的模型由Stokes-Kirchhoff公式计算了的松驰变细的结果相比,我们的模型的声学的变细的评价同意了他们。模型的精确取决于变细从产生的分子碰撞的物理机制的理解。另外,我们的模型的结果证明频率依赖者的人物声学的变细依靠煤气的混合物的作文。并且这能导致能够在各种各样的环境和进程决定煤气的作文的份量上的聪明的声学的煤气的传感器的开发。
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简介:Forthemulti-frequencyacousticanalysis,aseriesexpansionmethodhasbeenintroducedtoreducethecomputationtimeofthefrequency-independentparts,buttheRungephenomenonwillarisewhenthismethodisemployedinhighfrequencyband.Therefore,thismethodisimprovedbyanalyzingtheapplicationconditionandproposingtheselectionprincipleoftheseriestruncationnumber.Theargumentintervalcanbeadjustedwiththewavenumberfactor.Therefore,theproblemofunstablenumerationandpoorprecisioncanbesolved,andtheapplicationscopeofthismethodisexpanded.Thenumericalexampleofacousticradiationshowsthattheimprovedmethodiscorrectforacousticanalysisinwiderfrequencybandwithlessseriestruncationnumberandcomputationamount.
简介:Thispapergivesthedirectivityfunctionofasectoralmul-ti-elementcylinderarray,analyzeitsphasefactor,explainindetailthesideloberejectionbyselectingthenumberofelements,bafflingandamplitudeweighting.Theyareparticularlyusefulfordirectionaltrackingofacousticalsignalandtargetlocating.
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。
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简介:Thenumericalquadraturemethodsfordealingwiththeproblemsofsingularandnear-singularintegralscausedbyBurton-Millermethodareproposed,bywhichtheconventionalandfastmultipoleBEMs(boundaryelementmethods)for3Dacousticproblemsbasedonconstantelementsareimproved.Tosolvetheproblemofsingularintegrals,aHadamardfinite-partintegralmethodispresented,whichisasimplifiedcombinationofthemethodsproposedbyKirkupandWolf.Theproblemofnear-singularintegralsisovercomebythesimplemethodofpolartransformationandthemorecomplexmethodofPART(ProjectionandAngular&RadialTransformation).Theeffectivenessofthesemethodsforsolvingthesingularandnear-singularproblemsisvalidatedthroughcomparingwiththeresultscomputedbytheanalyticalmethodand/orthecommercialsoftwareLMSVirtual.Lab.Inaddition,theinfluenceofthenear-singularintegralproblemonthecomputationalprecisionsisanalyzedbycomputingtheerrorsrelativetotheexactsolution.ThecomputationalcomplexitiesoftheconventionalandfastmultipoleBEMareanalyzedandcomparedthroughnumericalcomputations.Alarge-scaleacousticscatteringproblem,whosedegreeoffreedomsisabout340,000,isimplementedsuccessfully.Theresultsshowthat,thenearsingularityisprimarilyintroducedbythehyper-singularkernel,andhasgreatinfluencesontheprecisionofthesolution.TheprecisionoffastmultipoleBEMisthesameasconventionalBEM,butthecomputationalcomplexitiesaremuchlower.