简介：Theformationoffreeradicals（?）OHand（?）Hinanaturallyair-saturatedaqueoussolutionexposedtotherapeuticCWultrasoundatafrequencyof820kHzhasbeenconfirmedbyusingspintrapping5,5-dimethyl-1-pyrroline-1-oxide（DMPO）andelectronspinresonance（ESR）technique.Itissuggestedthattheseradicalsareformedduetothehightemperatureandpressureproducedbytheultrasonictransientcavitation.Thetransientcavitationthresholdisfoundat0.537-0.632W/cm2underasonicationtimeof3minutes.Withincreasingsoundintensitytheyieldoffreeradicals（?）OHraisesrapidlyattheintensityrangingfrom1—2W/cm2,andnolongerincreaseisobservedatabove3W/cm2.Thesoundintensity（I）dependenceoftheyieldof（?）OH（D）canbeapproximatelydescribedbyaregressionequation:D=8.1(I1/2-（Ic）1/2)1/2,whereIc=0.667W/cm2.UnderafixingsoundintensitytheyieldofOHincreasesmonotonouslywiththesonicationtime.

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：Toremovethescatteringeffectofthedisturbingsoundonthetargetsourcewhenimplementingnearfieldacousticholographyinanon-freefield,afreefieldrecoverytechniquebasedonthesphericalwavesuperpositionmethodisproposed.Inthemethod,thesoundfieldseparationtechniquebasedonthesphericalwavesuperpositionmethodisfirstusedtoseparatetheincomingandoutgoingfields,andafurtherstepforseparatingtheradiatedandscatteredfieldsisperformedbyutilizingthesurfaceadmittanceofthetargetsourceastheboundaryconc1ition.Thetechniquemakesitpossibletocorrectlyidentifynoisesourcesinanon-freesoundfeld.Thebasicprincipleofthetechniqueisdescribedfirstly,amethodforchoosingtheoptimalnumberofsphericalwaveexpansiontermsisgiven,andtwonumericalsimulationsareusedtodemonstratethevalidityofthistechnique.Itisshownthat,forthelowerfrequency,thescatteringeffectcanbeneglected,andtheradiatedfieldofthetargetsourcecanbeobtainedbythesoundfieldseparationtechnique,however,astheincreasingofthefrequcncy,thescatteringeffcctcannotbeneglected,andthefrecfieldrecoverytechniquehastobeusedtoobtaintheradiatedfieldofthetargetsource.

简介：Inanon-freefield,theexistenceofdisturbingsourceswoulddestroythefree-fieldconditionrequiredbynear-fieldacousticholography,andconfusetheidentificationoftargetsourceduetothescatteringeffectcausedbydisturbingsoundfallingonthetargetsource.Tototallyremovetheinfluenceofdisturbingsource,amethodforrecoveringandreconstructingthetargetsoundfieldinanon-freefieldwasproposedbasedontheequivalentsourcemethodandthepressure-velocitymeasurement.Intheproposedmethod,thesoundfieldseparationtechniquewasfirstlyusedtoseparatethemixedsoundfieldintotheoutgoingfieldcomingfromthetargetsourceandtheincomingfieldcomingfromthedisturbingsource.Thenthescatteredcomponentcontainedintheoutgoingfieldwascalculatedbyusingthedisturbingsoundandthesurfaceimpedanceofthetargetsource.Finally,thesoundfieldradiatedbythetargetsourceinafreefieldwasobtainedbysubtractingthescatteredcomponentfromtheoutgoingfieldandwasfurtherusedtoreconstructthesoundfieldofthetargetsource.Theproposedmethodwasnumericallyandexperimentallytestifiedandtheresultsofboththesimulationandtheexperimentdemonstratedthevalidityoftheproposedmethod.