简介:Themutualradiationimpedanceignoredinconventionalarraydirectivityformulaisintroducedintothecalculationofarrayradiationsoundfield,andamodifiedarraydirectivityformulaconsideringthemutualradiationimpedanceisgainedaccordingtothesuperpositionprinciple.Resultsofcomputersimulationandexperimentsforauniformlineararrayandauniformplanararrayshowsuperiorperformanceonthepresentofthepracticaldirectivitypatternofthemodifiedformulainthispaperincomparisontotheconventionalone.
简介:这篇论文论述平面纤维布拉格栅栏(FBG)水中听音器探查察觉到原则,并且理论上并且试验性地研究探查结构敏感,收到的敏感频率反应特征和加速反应性质。平面表用不锈钢做的,它的厚度是0.15公羊,它的直径是空圆形的壳的15mm,和长度是20公羊。为结构的这种尺寸,探查结构敏感直到23fm/Pa,它是大约7300次赤裸的纤维的价值。回声频率是6.5kHz,和反应是的收到的敏感的振幅频率曲线相对在到5.5kHz的100Hz的频率范围以内的命令。一单位加速(1m/s2)产出的产量等价于(2.52~3.26Pa)声学的压力代理输出。这探查结构是容易的由multiplexingtechnique.The研究表演形成FBG水中听音器数组这平面结构能不仅形成FBG水中听音器探查,而且能组成光FBG激光水中听音器探查。结构能认识到不同带宽,不同范围由调整表的几何尺寸的声学的压力测量。
简介:Thedispersioncharacteristicsandexcitationmechanismsoftheguidedwavesinmultilayeredplatesarestudiedinthispaper.Firstly,thedispersionequationisobtainedbythepropagatormatrixmethod.Then,thebisectiontechniqueisemployedtofindalltherootsofthedispersionequation.Thedispersioncharacteristicsoftheguidedwavesareinvestigatedandanalyzed.ForthemultilayeredplatesinwhichtheS-wavevelocityincreasesordecreasesfromtoptobottom,itisfoundthatthevelocitylimitsinhighfrequencyofthefirstandhighmodesareequaltotheRayleighwaveandS-wavevelocitiesofthelow-velocitylayer,respectively.ItisalsofoundthatthevelocitylimitsinthehighfrequencyofallmodesareequaltotheS-wavevelocityofthelow-velocitylayerfortheplatewithalow-velocitymiddlelayer.Thenormaldisplacementspectrumofallthemodesexcitedbythenormalforcesourcewithadefinitewidthonthesurfaceoftheplateisalsoinvestigated.ItisprovedthatthedominantmodeisthefirstmodewhentheS-wavevelocityincreasesfromtoptobottomlayerandthedominantmodeisdifferentindifferentfrequencyrangefortheplatewithalow-velocitymiddlelayer.
简介:InordertoreconstructcomplicatedtemperaturefieldsmoreaccuratelybyacousticCT,areconstructionalgorithmbasedonMarkovradialbasisfunctionandTikhonovregularizationisproposedandnamedasMTRalgorithm.Withthealgorithm,theacousticvelocityfieldinamediumisapproximatedbyalinercombinationofMarkovradialbasisfunctions,theacoustictravel-timesovermulti-pathsandtheTikhonovregulationareusedtoreconstructtheacousticvelocitydistribution,andthenthetemperaturedistributioniscalculatedbyusingtherelationshipbetweenacousticvelocityandtemperature.Thetemperaturefieldmodelswithonehotspot,threehotspotsandfivehotspotsarereconstructedbyusingsimulationdata.ReconstructionresultsshowthattheMTRalgorithmcanreconstructthehottemperature,especiallythehotpositionaccurately.AnexperimentsystemfortemperaturedistributionmeasurementbyacousticCTisdeveloped.ThecapabilityofacousticCTtodetectahotspotcreatedbyelectricheatersinanexperimentalsilofilledwith1200kgsoybeansistestedbyusingtheMTRalgorithm.Inthereconstructiontemperaturefield,thehotpositioncanbedeterminedcorrectlyandthetemperatureerrorofthehotspotis1.3%.ItisthusclearthattheMTRalgorithmhasagoodcapacityofreconstructingcomplextemperaturefields,andcanbeexpectedtobeusedintemperaturemonitoringforactualstoredgains.
简介:Prosodiccontrolisanimportantpartofspeechsynthesissystem.Prosodicparameterschoicerightorwronginfluencesthequalityofsyntheticspeechdirectly.Atpresent,texttospeechsystemhaslesseffectivedescribetoreflectdatarelationshipsinthecorpus.Anewresearchapproach-dataminingtechnologytodiscoverthoserelationshipsbyassociationrulesmodelingispresented.Andanewalgorithmforgeneratingassociationrulesofprosodicparametersincludingpitchparametersanddurationparametersfromcorpusisdeveloped.Theoutputrulesimprovethecorrectnessofsyllablechoiceintexttospeechsystem.
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:Theoreticalandexperimentalresearchoflowfrequencypulsecompressionandchannelmatchinshallowwatersoundchannelwerecarriedoutbasedon2000-WinterYellowSeaexperiment.Usingpulsecompressionmethod,signalswithhighsignaltonoiseratio(SNR)werereceivedoverrangeof110kilometersintheexperiment.TheSNRgainintheprocessisconsistentwiththetheoreticalprediction.Theexperimentalmeasurementindicatedthatthechannelishighlycoherentoveralengthof500s.ChannelmatchmethodwasusedtocompensatethedegradationofpulsecompressionSNRcausedbythemulti-pathpropagation.AndtheSNRgaininthechannelmatchprocesscanbetheoreticallypredicted.ExperimentalresultsshowthatlowfrequencypulsecompressionandchannelmatchmethodcanbeusedinshallowwatersoundchanneltoimprovetheSNR.
简介:Undertheconditionofhigh-powerdrive,theexperimentalphenomenaoffreestatoroftravelingwaveultrasonicmotortakesonstrongnonlineareffects.Firstly,itscorrespondingtheoriesareestablishedtoanalyzeandcomparethestator'sperformancesattheresonanceandantiresonancestates.Atthesametime,someimportantparameters,suchasresonance/antiresonancefrequency,mechanicalquality,electro-mechaniccoupling,andtherelativevibrationeffect,areselectedelaboratelytoevaluatethevibrationalperformancesoffreestator.Then,someexperimentalschemesbasedonthelaservibrationmeasurementaredesignedrespectively.Underthedifferentdrivesconditions,theexperimentalcharacterizationsoffreestatorattheresonanceandantiresonancestatesareanalyzedsystematically.Finally,Theinvestigativeresultsshowthattheperformanceattheantiresonancestateismuchbetterthanthatattheresonancestate.Someconclusionsofthispapercanprovidenovelideaandguidanceforthechoosingoftheoperatingstatesanddrivingmodesoftravelingwaveultrasonicmotor.
简介:常规MVDR适应beamformer是用真实的声学的地的narrowbandCSDM估计最佳的beamforming重量的高分辨率的narrowbandbeamformer。在实际应用,MVDR算法需要长观察时间估计协变性矩阵。这个固有的性质使本地化移动迅速的目标困难。为宽带信号,MVDR算法需要转换增加计算要求的每CSDM。为相关来源,因为信号将取消对方,MVDR的性能将戏剧性地降级。一个快会聚的MVDR算法基于subbandsubarray处理被建议。完整的频率乐队被划分成subbands的集合,线数组被划分成subarrays的集合。为每subband,减少的尺寸的STCM是计算的。快会聚的MVDR算法和空间光谱评价的然后适应的beamforming重量被获得。同时,空间光谱评价能用两方面的空间变光滑方法为相关来源被做。模拟和试用数据的结果证明建议方法有高分辨率、在即时附近的集中性质,两方面的空间变光滑有decorrelation的令人满意的有效性。
简介:为了测试信号阶段匹配的有效性,原则(SPMP)把评价用于到达(DOA)的方向,实验用16传感器数组在一座水库被执行。二种方法,为匹配原则(LSMSPM)的信号的最不方形的方法和为匹配原则(SVDSPM)的信号的单个值分解方法,被用于DOA评价。他们的表演被分析并且与音乐相比并且常规形成横梁(CBF)方法。3dB横梁宽度由SPMP获得了的结果表演是到像由音乐method.In增加,LSMSPM和SVDSPM由CBF和1/2获得了到1/3那一样的1/7的1/4为多来源DOA评价和高度是可得到的分辨率DOA评价,它证明由SPMP方法的那个DOA评价由音乐和CBF方法比那好。
简介:Aspace-timecoupledspectralelementmethodbasedonChebyshevpolynomialsispresentedforsolvingtime-dependentwaveequations.Acousticpropagationproblemsin1+1,2+1,3+1dimensionswiththeDirichletboundaryconditionsaresimulatedviaspace-timecoupledspectralelementmethodusingquadrilateral,hexahedralandtesseracticelementsrespectively.Space-timecoupledspectralelementmethodcanobtainhigh-orderprecisionovertime.Withthesametotalnumberofnodes,highernumericalprecisionisobtainedifthehigher-orderChebyshevpolynomialsinspacedirectionsandlower-orderChebyshevpolynomialsintimedirectionareadopted.Numericalillustrationshaveindicatedthatthespace-timealgorithmprovideshigherprecisionthanthesemi-discretization.Whenspace-timecoupledspectralelementmethodisused,timesubdomain-by-subdomainapproachismoreeconomicalthantimedomainapproach.