PROGRAM OF M The 134th Meeting of the Acoustical Society of America A N. O M 1–5 December 1997 a 1 NOTE: All Journal articles and Letters to the Editor are peer reviewed before publication. Program abstracts, however, are not reviewed before publication, since we are prohibited by time and schedule. MONDAY MORNING, 1 DECEMBER 1997 EL CAMINO/ADOBE ROOMS, 8:15 A.M. TO 12:00 NOON Session 1aAO Acoustical Oceanography: Acoustic Measurement of Ocean Processes Eric Wolin, Chair Hughes Aircraft, Naval and Maritime Systems, 8080 Dagget Street, San Diego, California 92111 Contributed Papers 8:15 arrays433mapartinrange,withnosignificantrelativetimelagbetween the two. Though a zero relative time lag would imply a southeastern 1aAO1.AcousticmonitoringofflowthroughtheStraitofGibraltar. directionforthewavevector,thelongwavelengthsinvolvedandtheshort PeterF.Worcester (cid:126)ScrippsInst.ofOceanogr.,Univ.ofCaliforniaatSan rangebetweenthearraysmakesuchapredictioninconclusive.Variations Diego,LaJolla,CA92093,[email protected](cid:33),UweSend (cid:126)Univ.of ofshorterdurationsarriveatthetwoarrayswitharelativetimelagthat Kiel, 24105 Kiel, Germany(cid:33), Bruce D. Cornuelle, and Christopher O. ranges between 5 and 26 min. Wavelet analysis has confirmed this time Tiemann (cid:126)Univ.ofCaliforniaatSanDiego,LaJolla,CA92093(cid:33) lag, and shows that it holds for a range of wavelengths. This puts con- The Strait of Gibraltar Acoustic Monitoring Experiment was con- straintsonthedirectionandspeedoftheshort-durationcomponents.The ductedduringApril–May1996todeterminethefeasibilityofusingacous- implications of these results on acoustic propagation will be discussed. ticmethodstomakeroutine,rapidlyrepeated,transportmeasurementsin (cid:64)WorksupportedbyONRandNRL.(cid:35) theStraitofGibraltar,aswellastoexploretheacousticscatteringcaused by the internal wave bores generated in the Strait. Three different ap- proachestomonitoringtheflowwereexplored:(cid:126)i(cid:33)high-frequency(cid:126)2-kHz(cid:33) 8:45 reciprocal transmissions; (cid:126)ii(cid:33) high-frequency (cid:126)2-kHz(cid:33) horizontal arrival angle measurements of ray bending due to currents; and (cid:126)iii(cid:33) one-way 1aAO3. Forward propagation analysis for the summer Shelfbreak transmissionsfromalow-frequency(cid:126)250-Hz(cid:33)sourcetoaverticalreceiv- PRIMER Experiment. Brian J. Sperry, Jim Lynch (cid:126)Dept. of Appl. ing array on the opposite side of the Strait. Extensive independent mea- Ocean Phys. and Eng., Woods Hole Oceanogr. Inst., Woods Hole, MA surementsofthetemperature,salinity,andvelocityfieldswerealsomade. 02543(cid:33),Ching-SangChiu (cid:126)NavalPostgrad.School,Monterey,CA(cid:33),Glen The deep-turning rays are stable and yield differential travel times that G. Gawarkiewicz, Robert S. Pickart (cid:126)Woods Hole Oceanograph. Inst., give reasonable values for the current components along the acoustic Woods Hole, MA 02543(cid:33), James H. Miller (cid:126)Univ. of Rhode Island, paths.Horizontalarrivalangles(cid:126)phasedifferences(cid:33)arestronglycorrelated Narragansett, RI(cid:33), and Allan R. Robinson (cid:126)Harvard Univ., Cambridge, with rough estimates of the current perpendicular to the acoustic path MA(cid:33) madeusingcurrentmeterdata,suggestingthatthisapproachisfeasibleat Oneoftheprimaryobjectivesofthe1996ShelfbreakPrimerExperi- rangesuptoatleast15km.Finally,theacousticsignalsshowtheeffects ofthenonlinearinternalwavespresentintheStrait.(cid:64)Worksupportedby ment,locatedintheMid-AtlanticBightsouthofNanucketShoals,wasto ONR.(cid:35) investigatetheeffectsoftheshelfbreakfrontonthepropagationofacous- tic signals. The acoustic component of the experiment consisted of two 16-elementverticalhydrophonearrays(cid:126)VLAs(cid:33)alongthenorthernedgeof 8:30 theregion(cid:126)inshoreoftheshelfbreak(cid:33),andthreesources(cid:126)one224Hzand two400Hz(cid:33)alongthesouthernedge(cid:126)seawardoftheshelfbreak(cid:33).Source- 1aAO2. Direction and speed of internal waves in SESAME II, and to-receiverpathlengthsrangedfrom40–60km.Thehigh-qualityoceano- their effect on acoustic transmission. Jacob George, Robert L. Field, andZachariahR.Hallock (cid:126)NRL,StennisSpaceCenter,MS39529(cid:33) graphic data collected, including SeaSoar sections and numerous ther- mistor records, are critical to modeling and interpreting the acoustics. AnalysisofthermaldatafromSESAMEIIhasrevealedvariationsof Fromamodalperspective,thereisstrongcouplingfromnotonlythefront, both long and short durations. Variations of long durations have been butalsofromtheslopingbathymetryandfromscatteringbysolitons.The clearlyidentifiedwithtidalcycles,andarenearlyidenticalattwothermal receptionsatthenortheastVLAcoincidingwitha6-dayperiodofSeaSoar 3061 J.Acoust.Soc.Am.,Vol.102,No.5,Pt.2,November1997 134thMeeting:AcousticalSocietyofAmerica 3061 Downloaded 11 Jul 2013 to 128.95.155.147. Redistribution subject to ASA license or copyright; see http://asadl.org/terms deployment are considered here. Fluctuations in the signal arrivals are describedinearlierwork(cid:64)Wageetal.,J.Acoust.Soc.Am.101,3113(cid:126)A(cid:33) consistentwiththepictureprovidedbythemeasuredoceanography.Re- (cid:126)1997(cid:33)(cid:35).Initialresultsrevealafrequencyselectivityinthearrivalsforthe sultsfromcoupled-modepropagationmodelingarealsodiscussed.(cid:64)Work lowesttenmodes.Sincefrequency-selectiveeffectscanbemodeledbya supportedbyONR.(cid:35) randommultipathchannel,theproblemofestimatingchannelcharacteris- tics from pulse-compressed M-sequence receptions is discussed. In par- ticular,thisstudyinvestigatesvarioustechniquesofaveragingacrossre- 9:00 ceptionstoobtainthemeanarrivaltimeandspreadforeachmode.(cid:64)Work 1aAO4.Pulsepropagationthroughcontinental-shelfinternalsolitary supportedbyONR.(cid:35) waves. Altan Turgut and Stephen N. Wolf (cid:126)Naval Res. Lab., Acoust. Div.,Washington,DC20375(cid:33) 9:45 Anewlydevelopedpseudospectralnumericalmodelisusedtostudy 1aAO7. MFP geoacoustic inversion applied to the WORKSHOP97 data. pulse propagation through continental-shelf internal waves. A time- A.Tolstoy (cid:126)IntegratedPerformanceDecisions,Inc.,Honolulu,HI96816(cid:33) domainmodecouplinganalysisisperformedonplane-wavepulsespropa- gatingthroughasimpleinternalsolitarywave(cid:126)ISW(cid:33)describedbydown- Applicationoftherefinediteratedgridsearch(cid:126)RIGS(cid:33)MFPinversion wardundulationofathermoclinehavingtheshapeofhyperbolicsecant. methodtofouroftheWORKSHOP97testcases(cid:126)SD,AT,SO,andWA(cid:33)has Initial acoustic fields made up of eight-cycle Hanning-weighted sine resultedinsomesurprisinglyaccurateestimatesforsomegeoacousticpa- waveswith224-and400-Hzcenterfrequencies(cid:126)verticallyshadedbyde- rameters, i.e., sediment densities and attenuations, source ranges and sired acoustic mode shapes(cid:33) are used. Two-dimensional and three- depths,andsomesedimentgradients.Anothersurprisewasthesensitivity dimensionalnumericalresultswerecomparedtoinvestigatethevalidityof oftheinversiontosmallerrorsintheKRAKENpropagationmodel.This two-dimensionaltechniquesinthecaseofnonparallelacoustic-ISWalign- paperwilldiscussrecenteffortstounderstandthebenefitsandshortcom- ment. Similar to the results of Preisig and Duda (cid:64)IEEE J. Oceanic Eng. ingsoftheRIGSmethodandtoproposefuturedirections. 22(cid:126)2(cid:33)(cid:126)1997(cid:33)(cid:35),ithasbeenobservedthatthehorizontalrefractionandazi- muthal scattering seem to be minor for up to 65-deg oblique incidence 10:00–10:15 Break angle.Resultsoftwo-dimensionalpropagationandmode-couplinganaly- sisfortheISWpacketsmeasuredduringtheSWARM95experimentare alsodiscussed.(cid:64)WorksupportedbyONR.(cid:35) 10:15 1aAO8. Modeling of broadband time signals in shallow water using 9:15 environmental inversion. Peter L. Nielsen (cid:126)Saclantcen, Viale S. Bartolomeo400,19138LaSpezia,Italy,[email protected](cid:33),Peter 1aAO5. Acoustic field propagation through a shallow water Gerstoft (cid:126)UCSD,LaJolla,CA92093-0704(cid:33),FrancescoBini-Verona,and waveguidedominatedbyinternalwaves. StevenFinette,MarshallOrr FinnB.Jensen (cid:126)Saclantcen,LaSpezia,Italy(cid:33) (cid:126)Acoust. Div. Naval Res. Lab., Washington, DC 20375(cid:33), John Apel (cid:126)Global Ocean Assoc., Silver Spring, MD 20908(cid:33), and The SWARM Anumericalmodelingschemeisappliedtoperformbroadbandenvi- Group ronmentalinversionbyusingexplosivedataacquiredintheMediterranean SeainMay1997.Theareashowsamoderaterangedependency,andthe The continental shelf off the New Jersey coast is a site of intense received time signals from explosive charges cover a frequency band of internal-waveactivity.Thespace–timevariabilityofanacousticfieldin several kilohertz. The acoustic propagation model is based on a layered thisshallow-waterregionwasstudiedusingoceanographicmeasurements normalmodeapproach,whichiscapableofefficientlypredictingbroad- along a 42-km track from the SWARM95 (cid:64)shallow-water acoustics in a band sound propagation in shallow water (cid:64)Westwood etal., ‘‘A normal random medium(cid:35) experiment. A sound–speed model based on the KdV mode model for acoustic–elastic ocean environments,’’ J. Acoust. Soc. equationwasdevelopedtoincludethenonlinearcontributionoftheinter- Am. 100, 3631–3645 (cid:126)1996(cid:33)(cid:35). This model has been extended to handle nalwavefield,withparametersestimatedfromtowedyo-yoctddata,ship range-dependent environments using the adiabatic approximation. Thus radarimagesofinternal-wavesurfaceexpressionandacousticbackscatter calculation of broadband transfer functions from 0 to 10 kHz of range- images of subsurface internal-wave structure. The linear internal-wave dependent,shallow-waterwaveguidescannowbedonewithinafewmin- contributionwasmodeledbyanADCP-deriveddisplacementpowerspec- utes.Thecombinationoftheabovepropagationmodelandastate-of-the- trum. Bathymetry and sub-bottom parameters were previously estimated art global inversion scheme (cid:64)Gerstoft, ‘‘SAGA user manual 2.0: An from wave-field inversions using chirp sonar surveys. Simulation results inversionsoftwarepackage,’’SACLANTCENSM-333(cid:126)1997(cid:33)(cid:35),makesit arepresentedforacousticpropagationatfrequenciesof224and400Hz possibletoperformenvironmentalfocusingbyoptimizingthecorrelation usingawide-angleparabolicequationmethodtocomputerealizationsof between the numerical and experimental received time signal at one or the acoustic field. Results include estimates of the intensity fluctuations morereceiverlocations.Thebroadbandinversionschemeisintroducedto and coherence for two vertical arrays located at 33 and 42 km from the extracttheuncertainacousticparametersinthewaveguide,andtoassess mooredsources.(cid:64)WorksupportedbyONR.(cid:35) howaccuratebroadbandsignalscanbemodeledincomplexshallow-water regions. 9:30 10:30 1aAO6. Normal mode analysis of acoustic thermometry of ocean climate receptions using short-time Fourier techniques. Kathleen E. 1aAO9. Broadband mode inversion for oceanographic and Wage, Arthur B. Baggeroer (cid:126)Res. Lab. of Electron., MIT, Cambridge, geoacousticparameters. GopuR.PottyandJamesH.Miller (cid:126)Dept.of MA02139andAppl.OceanPhys.andEng.Dept.,WoodsHoleOceanogr. OceanEng.,Univ.ofRhodeIsland,Narragansett,RI02882(cid:33) Inst.(cid:33),andJamesC.Preisig (cid:126)WoodsHoleOceanograph.Inst.(cid:33) Ageneticalgorithmwasusedfortheinversionofsoundspeedinthe Theeffectsofinternalwavesonthecoherenceofpropagatingmodes water column and sediment layers south of New England in the Middle andthevalidityoftheadiabaticassumptionareveryimportantissuesin Atlantic Bight. The experimental data were SUS charge explosions ac- bothmatched-fieldprocessingandacoustictomography.Whilemuchthe- quiredonaverticalhydrophonearrayduringtheShelfBreakPrimerEx- oretical research has been done on long-range propagation of modes in periment conducted in August, 1996. A genetic algorithm was used to deepwater,therehavebeenfewopportunitiestocomparetheoreticalpre- searchforoptimalparametersinawidespace;theEOFcoefficientsinthe dictionswithexperimentalmeasurements.Deploymentofmode-resolving oceanandthecompressionalsound–speedvaluesinthesedimentlayers. verticalarraysasapartoftheAcousticThermometryofOceanClimate Arange-independentnormal-moderoutinewasusedtoconstructtherep- (cid:126)ATOC(cid:33) experiment has provided data sets, which may offer insights licafieldscorrespondingtotheparameters.Comparisonofgroupspeeds about mode coherence at long ranges. This study examines the modal formodes1–4andforarangeoffrequenciesfrom10–100Hzwasused compositionofATOCreceptionsusingtheshort-timeFouriertechniques toarriveatthebestparameterfit.Alinearperturbativeinversionalsowas 3062 J.Acoust.Soc.Am.,Vol.102,No.5,Pt.2,November1997 134thMeeting:AcousticalSocietyofAmerica 3062 Downloaded 11 Jul 2013 to 128.95.155.147. Redistribution subject to ASA license or copyright; see http://asadl.org/terms doneonthesamedataasdescribedbyRajanetal.(cid:64)J.Acoust.Soc.Am. 11:15 82,998–1017(cid:126)1987(cid:33)(cid:35).Thislinearmethodalsogivesestimatesofresolu- 1aAO12. Tomographic reconstruction of shallow-water bubble fields tionandvariance.Analysiswasalsodonetocomputethedegreeofcon- observed in the Scripps Pier bubble experiment. Daniel Rouseff, vergenceofeachoftheparameters.Groupspeedsfortheinvertedsound– M FrankS.Henyey (cid:126)Appl.Phys.Lab.,CollegeofOceanandFisherySci., speed fields provide an excellent match to the experimental data. An A Univ. of Washington, Seattle, WA 98105(cid:33), Jerald W. Caruthers, and epfrfiesceienntetdh.y(cid:64)bWridorokpstiumpipzoarttieodnbscyhOemNeRu.(cid:35)singgeneticandlineartechniquesis StevenJ.Stanic (cid:126)NavalRes.Lab.,StennisSpaceCenter,MS39520(cid:33) ON. AnexperimentwasperformedintheSpringof1997offthepieratthe M ScrippsInstituteofOceanography.Theobjectivewastomeasurethenear- a 1 shore properties of bubble fields. A major component of the experiment wastheDeltaframedesignedatNRL-SSC.Thetriangularframe,9.4mon 10:45 eachside,supportedtwosourcesandeighthydrophones.Measurementsof 1aAO10.ObservationsofattenuationduringtheScrippsPierbubble acoustic travel time and attenuation were made at eight frequencies be- experiment. JeraldW.Caruthers,PaulA.Elmore,PhilipA.Beben,and tween 39 and 244 kHz. Details of the measurement apparatus will be StephenJ.Stanic (cid:126)NavalRes.Lab.,OceanAcoust.Branch,StennisSpace presentedelsewhereatthismeeting(cid:64)J.W.Caruthersetal.,‘‘Observations Center,MS39529(cid:33) ofattenuationduringtheScrippsPierbubbleexperiment’’(cid:35).Inthispaper, a tomography algorithm (cid:64)D. Rouseff and F. S. Henyey, J. Acoust. Soc. Anexperimentthatmeasuredtheeffectsofbubblesjustoffshorefrom Am. 101, 3032 (cid:126)1997(cid:33)(cid:35) is applied to a sampling of the data to produce activesurfwasperformedinthespringof1997offthepierattheScripps cross-sectional mappings of attenuation. The bubble concentrations are InstitutionofOceanography.Aregionfromafewtensofmetersto1000 showntobeinhomogeneousandcarriedacrosstheframebyripcurrents. mfromthebeachwasinstrumentedbyseveralresearchers.Anemphasis Possibleimprovementstothetomographyalgorithmforimagingstrongly was placed on a region approximately 400 m2 in area and about 300-m attenuatingstructuresarediscussed.(cid:64)WorksupportedbyONR.(cid:35) offshore where most of the instruments were clustered. Located in this area was a triangular-shaped frame called the Delta Frame, which had 11:30 sourcesattwoverticesandeighthydrophonesalongtheperimeter(cid:126)each 1aAO13.Attenuationestimatesforbubblyseawater. R.R.Goodman sidewas9.4mlong(cid:33).Eightfrequencies,from39to244kHz,werepropa- (cid:126)Appl. Phys. Lab., Penn State Univ., State College, PA(cid:33), P. A. Elmore, gatedsequentiallyfromeachsourceandreceivedoneachhydrophone.All andJ.W.Caruthers (cid:126)NavalRes.Lab.,StennisSpaceCenter,MS39529(cid:33) 16transmissionsoccurredwithin12msandwererepeatedata1-sinterval during each of ten 88-min data runs. Bubbles produced in the surf zone Acoustictechniquesusedfordeterminingbubbledistributionscanbe werecarriedouttotheexperimentalregionbyripcurrentsandhaddra- limited because a solution to an ill-conditioned inverse problem is re- maticeffectsonalltheinstruments.Thispaperdiscussestheireffectson quired. Examining cases in which closed-form solutions are possible, attenuationasmeasuredattheDeltaFrame.(cid:64)WorksupportedbyONR.(cid:35) however,maygiveusinsightabouttheinverseprocedure.Inaprevious ASA meeting (cid:64)Goodman, Caruthers, and Elmore, ‘‘Dispersion estimates for bubbly seawater,’’ J. Acoust. Soc. Am. 100, 3196(cid:126)A(cid:33) (cid:126)1997(cid:33)(cid:35), exact solutions for dispersion for the inverse procedure in special cases of bubbledistributionswereexplored.Heresomeofthosespecialcasesare 11:00 examined in terms of how they apply to attenuation measurements. For cases in which the closed-form solution are not possible, the resonant 1aAO11. Bubble clouds, velocity distributions, and high-frequency bubble approximation allows for estimating the bubble population from propagation in the Scripps bubble experiment. David M. Farmer, Svein Vagle (cid:126)Inst. of Ocean Sci., 9860 West Saanich Rd., Sidney, BC attenuationmeasurements.Thispapershowsthatthereisobservableerror V8L 4B2, Canada(cid:33), and Grant Deane (cid:126)Scripps Inst. of Oceanogr., La inthisprocedure,butthattheerrorcanbereducedbyapplicationofan Jolla,CA92093(cid:33) iterativeprocedurediscussedhere.(cid:64)WorksupportedbyONR.(cid:35) Aspartofanexperimenttodeterminethedistributionandacoustical 11:45 effects of bubbles near the surf zone, resonators, cameras, a coherent 1aAO14.Measuringnearsurfaceoceanfeaturesusingupwardfacing Doppler, and horizontally oriented Doppler sonars were deployed in the ADCPs. BrandonS.StrongandR.LeeGordon (cid:126)RDInstruments,9855 vicinityofScrippsPier.Withtheseinstruments,evolutionofthewavesas BusinessparkAve.,SanDiego,CA92131(cid:33) theytraveledtowardtheshoreweredetectedandthebubblesizedistribu- tions, rip currents, turbulence dissipation, and patterns of bubble cloud Thispaperpresentstheresultsofacousticmeasurementsoftheocean motionweremeasured.Propagationtestsat100kHzalonga230-mpath surfaceandnear-surfacefeaturesusingaconventionalbroadbandacoustic between the end of the pier and the surf were conducted. Bubble size Dopplercurrentprofiler(cid:126)ADCP(cid:33).Ananalysisofthetradeoffsanderror measurementsinthesurfandonabottom-mountedframeallowedidenti- sources associated with surface detection reveals how transducer beam ficationofthespatialevolutionofbubblecharacteristics.Thesonarmea- geometryandsignalprocessingcanaffectsurfacemeasurement.Configu- surementsshowbubblecloudsejectedoffshoreatdiscreteintervalsandat rationsareconsideredforthemeasurementofmean-surfaceheight,ambi- speeds of (cid:59)0.3 m/s. Pulse propagation into the surf was occasionally entsound,windspeed,winddirection,surfacecurrents,directionalwave completely attenuated by bubble clouds. However, it is interesting that spectra,tidalflow,andentrainedair.Observationsoftheseasurfacecon- prior to total blocking of the signal the pulse arrival time is delayed, ditions at Scripps Pier are compared with acoustic data collected using implying an apparent decrease in sound speed. This is unexpected since upwardfacingADCPsofdifferentbeamgeometriesandapressuresensor. our frequency (cid:126)100 kHz(cid:33) was above the resonance of the dominant Comparisons are made with previous studies (cid:64)Zedel, Deep ocean wave bubbles. An explanation is proposed in terms of selective blocking of measurementsusingaverticallyorientedsonar,J.Atmos.OceanicTech. directpathpropagationbybubbleclouds.(cid:64)WorksupportedbyONRCon- 11,182–191(cid:126)1994(cid:33)andTerrayetal.,Measuringwaveheightanddirec- tractsNos.N00014-96-C-6030andN00014-97-1-0288.(cid:35) tionusingupward-lookingADCPs,tobepresentedatOceans’97(cid:35). 3063 J.Acoust.Soc.Am.,Vol.102,No.5,Pt.2,November1997 134thMeeting:AcousticalSocietyofAmerica 3063 Downloaded 11 Jul 2013 to 128.95.155.147. Redistribution subject to ASA license or copyright; see http://asadl.org/terms MONDAY MORNING, 1 DECEMBER 1997 CABINET ROOM, 8:30 TO 11:15 A.M. Session 1aPA Physical Acoustics: Nonlinear Acoustics Bart Lipkens, Chair MacroSonics Corporation, 1570 East Parham Road, Richmond, Virginia 23228 Contributed Papers 8:30 givehigh-amplitudeshock-freewaveforms.Measurementsincavitiesde- signedwithRMSshowstanding-waveoverpressuresinexcessof340%of 1aPA1. Comparison between a nonlinear equation and acoustic ambient pressure, compared to maximum overpressures in cylindrical measurementinalaminategraphite-epoxycomposite. P.A.Elmorea(cid:33) cavitiesofabout17%.Powerisdeliveredbyoscillatingtheentireresona- and M. A. Breazeale (cid:126)Jamie Whitten Natl. Ctr. for Physical Acoust., toralongitsaxiswithalinearactuator(cid:126)entireresonatordrive(cid:33).Measure- Univ.ofMississippi,University,MS38677(cid:33) mentsareshownforfouraxisymmetricresonatorshapes:cylinder,cone, Measurements of longitudinal phase velocity and rate of harmonic horn-conehybrid,andbulb.Resonatorswerefilledwithnitrogen,propane, generation (cid:126)nonlinearity parameter(cid:33) have been made in a laminate or refrigerant R-134a (cid:126)1,1,1,2-tetrafluoroethane(cid:33). Ratios of peak-to- graphite-epoxy composite. Both quantities are observed to be frequency minimumpressuresof27wereobserved.Sincepracticalcompressorsfor dependent between 3.5 and 8 MHz. The theoretical model of Van Den air, refrigerants, or other gases require pressure ratios (cid:126)discharge to suc- Abeele and Breazeale (cid:64)J. Acoust. Soc. Am. 99, 1430–1437 (cid:126)1996(cid:33)(cid:35) has tion(cid:33) of 3 or more, RMS technology can be used in a wide range of been applied to the data. Including dispersion terms and their nonlinear applications. Frequency sweeps show softening or hardening behavior, counterpartsimprovesagreementoverthatobtainedwiththetheoryused depending on resonator shape. High-amplitude resonance sweeps show forsinglecrystals.Theoriginofthisdifferenceprobablyisinscattering significanthysteresis. from laminate boundaries. Some inadequacies still exist, however. Their origin has not been established yet. a(cid:33)Current address: Naval Res. Lab., OceanAcousticsBranch,StennisSpaceCenter,MS39529. 9:15 1aPA4. A theoretical model of nonlinear standing waves in an 8:45 oscillating cavity. Yurii A. Ilinskii, Bart Lipkens, Timothy S. Lucas, Thomas W. Van Doren, and Evgenia A. Zabolotskaya (cid:126)MacroSonix, 1aPA2. Modeling of harmonic generation and shock formation in 1570EastParhamRd.,Richmond,VA23228(cid:33) nonlinear surface acoustic waves in several real crystals. R. E. Kumon,M.F.Hamilton (cid:126)Dept.ofMech.Eng.,Univ.ofTexas,Austin, Atheoreticalinvestigationofnonlinearstandingwavesinanacousti- TX78712-1063(cid:33),Yu.A.Il’inskii,andE.A.Zabolotskaya (cid:126)MacroSonix calresonatorispresented.Themotivationforthisresearchstemsfromthe Corp.,Richmond,VA23228(cid:33) new technology of resonant macrosonic synthesis (cid:126)RMS(cid:33) developed at MacroSonix.RMScreateshighamplitudestandingwaves,e.g.,overpres- Harmonicgenerationandshockformationinnonlinearsurfaceacous- suresinexcessof300% ofambientpressure.Theanalysisisbasedona ticwavesthatpropagateinanisotropiccrystalswerestudiednumerically one-dimensionalmodelequationforthevelocitypotentialthatisderived onthebasisofanewtheoreticalmodelpresentedearlier(cid:64)Hamiltonetal., fromthefundamentalgasdynamicsequationsforanidealgas.Nonlinear- NonlinearAcousticsinPerspective,editedbyR.J.Wei(cid:126)NanjingUniver- ity,gasviscosity,andentireresonatordrivingareincluded.Theresonator sity Press, Nanjing, 1996(cid:33), pp. 64–69(cid:35). The theory applies for arbitrary isassumedtobeofanaxisymmetric,butotherwisearbitrary,shape.Non- elastic materials, surface cuts, and propagation directions. Numerical linear spectral equations are integrated numerically for a two-point simulations were performed for initially sinusoidal signals propagating boundary-valueproblem.Theharmonicamplitudesandphasesoftheve- across the surface of KCl, Ni, and Si crystals for the (cid:126)001(cid:33), (cid:126)110(cid:33), and locity potential wave are obtained directly from the solution of the (cid:126)111(cid:33) cuts, and over the appropriate range of directions for each cut. frequency-domainequations.Thepressurewaveshape,theharmonicam- Waveforms are shown to exhibit asymmetric distortion, well-defined plitudesofthepressurewave,andharmonicamplitudedistributionalong shockswithcuspedspikesinthehorizontalwaveform,andaphaseshiftin theresonatoraxisarethencalculated.Resultsarepresentedforthreereso- thezerocrossings.Solutionsforpropagationinthe(cid:126)001(cid:33)planeandinthe nator geometries: a cylinder, a cone, and a bulb. Both hardening and (cid:94)100(cid:38)directionofKClareshowntoexhibitatypicaltrappingofenergyin softeningbehaviorsareobservedandshowntobegeometrydependent.At the lowest order harmonics. Analytical solutions derived for the funda- high amplitude, hysteresis effects are present in the frequency-response mental and second-harmonic components for this particular case are in curves. Comparisons between measured and calculated waveforms show goodagreementwiththenumericalsolutionsclosetothesource.Although goodagreement. the phenomenon resembles one observed in nonlinear optics resulting fromdispersion,itisdueinsteadtopropertiesofthenonlinearitycoeffi- cientmatrix.(cid:64)WorksupportedbyONR.(cid:35) 9:30 1aPA5. Variation of B/A with 1/c for several liquids. M. Paul 9:00 Hagelberg (cid:126)Dept.ofPhys.,WittenbergUniv.,P.O.Box720,Springfield, 1aPA3. Measurements of macrosonic standing waves in oscillating OH45501-0720(cid:33) cavities. Christopher C. Lawrenson, Bart Lipkens, Timothy S. Lucas, DavidK.Perkins,andThomasW.VanDoren (cid:126)MacroSonixCorp.,1570 Theoreticalmodels(cid:64)B.Hartmann,J.Acoust.Soc.Am.65,1392–1396 EastParhamRd.,Richmond,VA23228(cid:33) (cid:126)1979(cid:33), B. Frank and J. D. N. Cheeke, J. Acoust. Soc. Am. 101, 1184– 1186(cid:126)1997(cid:33)(cid:35)predictthatthevariationofB/A,theacousticalnonlinearity Measurements of macrosonic standing waves in oscillating closed parameter, with the inverse sound speed 1/c, should be linear or linear cavities are shown. These cavities (cid:126)resonators(cid:33) were designed by Mac- withaquadraticterm.Confirmationofthesemodelsrequiresexperimental roSonixusingresonantmacrosonicsynthesis(cid:126)RMS(cid:33)toshapetheresultant dataforB/A vs1/c forindividualliquids.Suchdatawillbepresentedfor waveform. By controlling the nonlinear processes by which energy is severalliquidsincludingpurewater,seawater,mercury,andanumberof transferredtoharmonicfrequencies,RMSallowsdesignofresonatorsthat organicliquids. 3064 J.Acoust.Soc.Am.,Vol.102,No.5,Pt.2,November1997 134thMeeting:AcousticalSocietyofAmerica 3064 Downloaded 11 Jul 2013 to 128.95.155.147. Redistribution subject to ASA license or copyright; see http://asadl.org/terms 9:45–10:00 Break istoestimatetheamplificationlevelofthewaveintensityastheresultof suchkindsofinteractions.Thewaveamplitudesinapassivebubblymedia turnedouttobeamplifiedbyoneorderofmagnitudeinthecollisionplane 10:00 and their amplification depends on the bubble concentration k as M 0 1aPA6. An improved theoretical model for highly nonlinear bubbly pmax(cid:53)2(cid:49)24.5(cid:149)k01/4. The possibilities of simulating the hot-spot mecha- A liquids. Zhemin Zhu, Xiaoliang Zhao, and Gonghuan Du (cid:126)Inst. of nism of liquid explosive detonation ignition and the mechanism of the N. Acoust.andStateKeyLab.,NanjingUniv.,Nanjing210093,P.R.China(cid:33) large-scaleexplosionsofcontainersfilledwithafuelbybubblydetonation O waveinteractionsarediscussed.(cid:64)WorksupportedbyRFFR,Grant96-02- M Strongnonlinearityofbubblyliquidsisamostinterestingpropertynot 19369.(cid:35) a only for its theoretical importance in nonlinear acoustics but also for its 1 potential application in, for example, ultrasound imaging technology. A 10:45 physicalmodelwhichdescribesthenonlinearpropertyofliquidscontain- inguniformsizebubblesispresented(cid:64)UltrasoundMed.Biol.21,545–552 1aPA9.Fastnumericalalgorithmforsimulationofnonlinearacoustic (cid:126)1995(cid:33)(cid:35).Thetheoryissuccessfultosomeextentbutstillhassomelimita- waveswithshocksoffinitethickness. OlegA.SapozhnikovandVera tionssincethesizesofthebubblesareusuallynotexactlythesame.Inthis A. Khokhlova (cid:126)Dept. of Acoust., Phys. Faculty, Moscow State Univ., paper,amodeldealingwithmorepracticalsituations,i.e.,liquidscontain- Moscow119899,Russia,[email protected](cid:33) ingmanybubbleswhosesizesarerandomlydistributedisextended.The effectivenonlinearityparameterB/A (cid:126)ashighasabout104) andattenua- In an earlier work (cid:64)V. A. Khokhlova and O. A. Sapozhnikov, J. tioncoefficientforthesebubblyliquidsaregiven.Calculationsandcom- Acoust. Soc. Am. 96, 3321 (cid:126)1994(cid:33)(cid:35), a modified spectral approach was parisonsshowthattheimprovedmodelexplainstheexistentexperiments proposed for the description of nonlinear waves containing shocks. An moresatisfactorily.(cid:64)WorksupportedbytheNationalScienceFoundation abrupt shock has an analytical high-frequency (cid:118)(cid:50)1 asymptote. This ofChina.(cid:35) asymptoticresultwasusedinthenumericalalgorithmtomodelstrongly nonlinear waves with a relatively few number of harmonics N(cid:59)20 (cid:64)Pischal’nikov etal., Acoust. Phys. 42, 362–367 (cid:126)1996(cid:33)(cid:35). However, in 10:15 realdissipativemediumtheshockfrontisnotadiscontinuity,butatran- 1aPA7.Nonlinearphenomenaofhigh-amplitudevibrationofapiston sitionregionoffinitethickness.Thisregioncanbeadequatelydescribed in a gas-filled liquid. Oleg Rudenko and Valery Andreev (cid:126)Dept. of byahyperbolictangentprofile,sothatthecorrespondentwavespectrum Acoust.,Phys.Faculty,MoscowStateUniv.,Moscow119899,Russia(cid:33) athighfrequenciesisgovernedbytheFaysolution.Here,theFayspec- trumasymptoteofthefinitethicknessshockisused,insteadofthe(cid:118)(cid:50)1 Nonlinear phenomena are known to be significant after the wave of asymptote of the abrupt shock, to derive a set of coupled differential moderate amplitude passes a long distance through a weakly dissipative equationsfortheharmonicamplitudes.Severalmodelproblemsarecon- medium. Such ‘‘accumulative’’ effects are studied exhaustively by non- sidered.Itisshownthatthismethodpermitsincreasingtheaccuracyand linear wave physics. In contrast, the ‘‘local’’ nonlinearities are studied stabilityofthemodifiedspectralapproach,andstillleadstoareductionin incompletely. Such nonlinear behavior can be demonstrated by a piston thenumberofequationsbyafactorof10–100incomparisonwithdirect immersed in liquid and vibrating with high amplitude. This piston sub- frequencydomainschemes.(cid:64)WorksupportedbyFIRCAandRFBR.(cid:35) jectedtoaharmonicloadcanradiatenotonlythefundamentalfrequency but high-order harmonics as well. Moreover, reaction to high-power ra- 11:00 diation can create an additional nonlinear resistance to a piston motion. Local nonlinear phenomena are expessed clearly at vibration velocities 1aPA10.Nonlineareffectsfortorsionalwavesinrodswithcracklike comparablewiththesoundspeedofthesurroundingmedium.Suchacase defects. IgorN.Didenkulov,AlexanderE.Ekimov,andVyacheslavV. canberealizedusingliquidscontaininggasbubbleswheresoundvelocity Kazakov (cid:126)Inst. of Appl. Phys., 46 Ulyanov St., Nizhny Novgorod, ismuchlessthanoneinapureliquid.Thisworkisdevotedtothetheo- 603600,Russia(cid:33) reticalcalculationofthetemporalandspectralcharacteristicsofanonlin- The enormously high nonlinear response of solids with cracks to an earwaveradiatedbyapistonsubjectedtoaharmonicexternalforce.Two acoustic excitation makes nonlinear methods possible for nondestructive differentproblemsarediscussedcorrespondingtothepistonconsideredas alinearandasanonlinearvibratingsystem.(cid:64)WorksupportedbyRFFIand testing(cid:126)NDT(cid:33).Amongtheproblemstobesolvedarethemechanismsof CRDF.(cid:35) suchnonlinearresponsesandthedevelopmentofNDTmethods.Results of an experimental study of nonlinear effects for elastic waves in metal rodswithcracklikedefectsandtheirdependenceonthetypeofcontactsin 10:30 thecracksaregiven.Unlikeearlierworksconcernedmainlywithlongitu- dinal and flexural waves in solids, the present experiment shows that a 1aPA8. Shock-wave collisions in bubbly liquids: Numerical studies. Valery K. Kedrinskii (cid:126)Lavrentyev Inst. of Hydrodynam., Lavrentyev highdegreeofnonlinearityisfoundfortorsionalwavesaswell.Thecrack prospect15,Novosibirsk630090,Russia(cid:33) wasmodeledbycuttingarodandtightlyfillingacrackwithmetalplates. Twotypesofcontactwerestudied:dryandlubricatedcontacts.Modula- The results of numerical investigations of different effects arising in tionofhigh-frequencytorsionalwaves(cid:126)20kHzand22.8kHz(cid:33)inarodby bubblyliquidduetowaveinteractionsarepresented.Theinfluenceofthe low-frequency flexural vibrations was studied. Flexural vibrations were gas content on the parameters and the structure of shock waves and of excitedintwoways:withashockandwiththehelpofavibrator.Ampli- chemical reactions in the gas phase will be considered. The problem is tudemodulationwasobservedonlyinarodwithacrack,thelevelofthis solvedwithintheframeworkofthetwo-phasemathematicalmodelinclud- modulation drastically decreasing in the presence of liquid lubricant. ingthekineticequationsforthedescriptionofthemedium-statedynamics, (cid:64)Work supported by RFBR, Russia—Grant No. 97-02-17524—and by thermoexchangeaswellasofbimolecularreactionkinetics.Thepurpose INCAS,NizhnyNovgorod,Russia.(cid:35) 3065 J.Acoust.Soc.Am.,Vol.102,No.5,Pt.2,November1997 134thMeeting:AcousticalSocietyofAmerica 3065 Downloaded 11 Jul 2013 to 128.95.155.147. Redistribution subject to ASA license or copyright; see http://asadl.org/terms MONDAY MORNING, 1 DECEMBER 1997 CHAMBER ROOM, 8:15 TO 11:45 A.M. Session 1aSA Structural Acoustics and Vibration: Structural Vibration and Radiation Courtney B. Burroughs, Chair Applied Research Laboratory, The Pennsylvania State University, P.O. Box 30, State College, Pennsylvania 16801 Contributed Papers 8:15 9:00 1aSA1. A vibro-acoustic method for measuring Young’s modulus of 1aSA4. Far-field acoustic holography onto cylindrical surfaces using buildingmaterials. WingChu (cid:126)IndoorEnviron.Program,Inst.forRes. pressuremeasuredonsemicircles. AndrewNorris (cid:126)Dept.ofMech.and inConstruct.,Natl.Res.CouncilCanada,Ottawa,ONK1A0R6,Canada(cid:33) Aerosp. Eng., Rutgers Univ., Piscataway, NJ 08855-0909, [email protected](cid:33) ThecurrentASTMstandardsforthemeasurementsofYoung’smodu- lus are designed specifically for ceramics, bricks, carbon and graphite AsimpleformulawasrecentlyproposedbyWilliams(cid:64)J.Acoust.Soc. materials, and concrete. The techniques used are based on the measure- Am. 99, 2022–2032 (cid:126)1996(cid:33)(cid:35) for imaging pressure and velocity on a vi- ment of either sonic velocity or the resonant frequency in the flexural brating circular cylindrical shell using the far-field pressure measured modeofvibrationofthespecimen.Thelattermethodhasbeenadaptedfor along a meridional semicircle. The method is discussed and some new determining the Young’s modulus of building materials, such as wood, gypsum board, and oriented-strand-board (cid:126)OSB(cid:33), in the Acoustics Labo- results are presented. The procedure is generalized to handle cylindrical surfacesofanoncircularbutconvexcrosssection.Itisdemonstratedthat ratory of IRC/NRC using modern digital-signal processing. This paper will discuss the method and provide results for a number of building Williams’formulapredictsasupersonicsurfaceintensity,whichgivesthe materialstested. same meridional energy flux as the exact radiated far-field pressure. A modificationofWilliams’formulaissuggested,whichusespressuredata fromseveralneighboringsemicircles,althoughcompletesphericalcover- ageisnotrequired.Themodifiedimagingformulaisbaseduponthefirst twotermsinanasymptoticexpansioninthedimensionlesswavenumber. 8:30 The leading-order term yields the original formula, and the second term 1aSA2.Radiationofsoundbytwoconcentricfree-floodedcylindrical resultsinaboundarylayertypeofcorrectioninthecircumferentialdirec- shellsexcitedbyapointforce. K.StevenKim (cid:126)SignaturesDirectorate, tion.Numericalexamplescomparetheexactsupersonicacousticintensity CarderockDiv.,NavalSurfaceWarfareCtr.,9500MacArthurBlvd.,West onacylinderwiththatfromtheoriginalandthemodifiedformula.These Bethesda,MD20817-5700(cid:33) indicatethatthecircumferentialon-surfaceresolutionissignificantlyen- hanced by combining data from neighboring semicircles, even when the Radiated acoustic pressure fields are obtained when two concentric totalfar-fieldsphericalcoverageissmall.(cid:64)WorksupportedbyONR.(cid:35) free-flooded cylindrical shells of finite lengths are excited by a time- harmonicpointforce.Integralequationsareformulatedforthetwoelastic thinshellswithsimplysupportedboundaryconditionsatbothends.Near andfar-fieldacousticpressuresarecalculatedandeffectsofacousticcou- plingbetweentwoshellsarediscussed. 9:15 1aSA5. Acoustic modeling of oscillatory hydrodynamic loading and fluid–structure interaction. Ashok Gopinath and Gary W. Sweany (cid:126)Dept.ofMech.Eng.,CodeME/Gk,NavalPostgrad.School,Monterey, 8:45 CA93943,[email protected](cid:33) 1aSA3. Radiation from small acoustic sources located close to a Anexperimentalstudyhasbeenconductedofforcesonacylinderina submerged, compliantly coated cylindrical shell. Michael D. Gray, GaryW.Caille (cid:126)UnderseaRes.ProgramOffice,GeorgiaTech.Res.Inst., standing acoustic wave. The cylinder is representative of the leg of an 505 Tech Way N.W., Atlanta, GA 30318(cid:33), John R. Bogle, and Peter H. offshorestructureorplatform,whiletheacousticfieldisrepresentativeof Rogers (cid:126)GeorgiaInst.ofTechnol.,Atlanta,GA30332(cid:33) theoscillatorywaveloadingonsuchastructure.Apistonoscillatordrive mechanismprovidestherequisitelargeacousticamplitudesinthepressure vesselresonatorthathousesthetestcylinder.Theuseofahigh-pressure Measurements were made of the radiation from individual, small acoustic sources located close to a submerged, compliantly coated, thin gas allows the desired high values of the Reynolds numbers to be cylindricalshellinthe1(cid:44)ka(cid:44)20frequencyrange,wherekistheacous- achieved.Bothin-linedragforcesandtransverse(cid:126)lift(cid:33)forcesonthecyl- ticwavenumber,anda istheradiusofthecoatedcylinder.Thebehavior inder, along with the phasing information, have been measured with the of the radiated pressure field is shown to have two distinct frequency help of suitably mounted strain gauges, and corroborated with existing regimes. For ka(cid:46)5, the field is simple, and is well approximated by a data in the literature. Higher harmonic forces and resonant interactions, sourceanditsnegativeimage.Forka(cid:44)4, thepressurefieldischaracter- typical of compliant structures, have also been measured and analyzed. izedbysignificantspatialvariations,owingtocontributionsfromtheelas- This experimental technique appears to have a promising potential for ticresponseofthecoatedcylinder.Finite-elementmodelresultsarecom- studyingthelargeamplitude,largeReynoldsnumberregimeofhydrody- pared with the measurements, and are used to provide insight into the namicloadingandtheresultingfluid–structureinteractions. interactionsbetweenthesourceandthecoatedshell.(cid:64)Worksupportedby ONR.(cid:35) 3066 J.Acoust.Soc.Am.,Vol.102,No.5,Pt.2,November1997 134thMeeting:AcousticalSocietyofAmerica 3066 Downloaded 11 Jul 2013 to 128.95.155.147. Redistribution subject to ASA license or copyright; see http://asadl.org/terms 1aSA6.Abstractwithdrawn tivelyhighfrequencies.Todemonstratethegeneralaccuracyofthecalcu- lations, radiation efficiencies are computed for submerged unbaffled plates,andtheresultsarecomparedtoreverberationmeasurementsandto fullynumericalpredictions. M A 10:15–10:30 Break N. O M 10:30 a 9:30 1 1aSA10. Mechanical and radiated power and radiation efficiency of 1aSA7. Modification of the four-load method to compute source point driven panels. J. Ertel (cid:126)Phys. Dept., U.S. Naval Acad., 572 impedance in a pipe system. B. S. Sridhara (cid:126)Dept. of Eng. Technol. Holloway Rd., Annapolis, MD 21402-5026, [email protected](cid:33), J. andIndustrialStudies,MiddleTennesseeStateUniv.,Murfreesboro,TN Dickey,andG.Maidanik (cid:126)DavidTaylorRes.Ctr.,Annapolis,MD(cid:33) 37132(cid:33) The radiation and partial radiation efficiencies from point and line Thispaperdiscussesanewmethodusedtoobtainthesourceimped- drivenpanelswerepreviouslydefinedandinvestigatedbytheauthors(cid:64)J. ancefromthefour-loadmethod.Thethreenonlinearalgebraicequations Acoust. Soc. Am. 98, 2888(cid:126)A(cid:33) (cid:126)1995(cid:33) and J. Sound Vib. 144, 71–86 ofthefour-loadmethodweremodifiedtogivethreeequationsofacircle. (cid:126)1991(cid:33)(cid:35).Inthispaper,themechanicalpowerdissipatedinapointdriven At each frequency, the intersections of these circles give the real and fluid loaded panel is studied and compared to the radiated power. The imaginarypartsofthesourceimpedance.Acomputerprogramwasdevel- interdependenceofthemechanicalandtheradiatedpowersisinvestigated, oped to calculate these intersections and extract the realistic values. A andtheyarerelatedasfractionsofthetotalinputpower.Thedependen- frequencyrangefrom0to800Hzwasconsideredfora0.2286-m(cid:126)9-in.(cid:33) ciesofthemechanicalandradiatedpoweronfrequency,fluidloading,and diam pipe system with a loudspeaker as the sound source. At each fre- mechanicallossarefurtherstudied.Inthepresentpaper,themechanical quency, the circles were scanned from 0° to 360° in intervals of 0.5° power as well as the radiation efficiency is shown to increase with in- allowingsmallpercentageerrorssuchas0.001,0.005,and0.01.Thecom- creaseddampinginapanelwhiletheradiatedpowerdecreases,asitmust. putedsourceimpedancevalueswerecomparedwiththoseobtainedfrom These results again show the fallibility of the conclusion that ‘‘a higher thedirectmethod.Theresultsagreewellwiththedecreaseinthepercent- radiationefficiencynecessarilyimpliesmoreradiatedpower.’’Theresults ageerror. ofcomputerexperimentsarecitedinnumericalexamples. 9:45 10:45 1aSA8. Method for broadband measurement of complex shear 1aSA11. Interaction between wave-number pairs. Jean-Franc¸ois Ille modulus and Poisson ratio of viscoelastic materials. L. Sheiba andJerryH.Ginsberg (cid:126)G.W.WoodruffSchoolofMech.Eng.,Georgia (cid:126)NRaD,53560HullSt.,SanDiego,CA92152-5001(cid:33) Inst.ofTechnol.,Atlanta,GA30332-0405(cid:33) Thismethodisbasedontheinversesolutiontothevibrationproblem Whenacoustic-structureinteractionisanalyzedaccordingtothewave- ofafiniteelasticcylinderwithreinforcedtorsionsurfacesbyrigidseptaor number-basedversionofthesurfacevariationalprinciple(cid:126)SVP(cid:33),consid- plates.Inallcasesthepolymerlayertobetestedisbondedtorigidplates; erablecomputationaleffortisrequiredtogenerateeachcoefficientinthe therefore, the radial displacement is zero at the boundary between the quadratic sum forming the variational quantity. Examination of the wet- polymer layer and the septum. The admittance matrix Y of the element surfaceimpedance,whichrepresentsthespectrumofpressureamplitudes with abovementioned boundary conditions is constructed within the generatedbyaspecifiedspectrumofsurfacevelocityamplitudes,reveals frameworkofthehypothesisforplanarcrosssections.Thedimensionless thatmanycross-impedancetermsareverysmall.Thissuggeststhatsome shearwavenumberkt((cid:118))handcompressionwavenumberk(cid:108)((cid:118))h,which coefficientsneednotbecomputed.Thepaperintroducesseveralapriori- aretheunknownvariables,areobtainedbymeasuringthetransfermatrix criteria for selecting the impedance terms to be omitted, based on the ofaknownstructureandasaresultofsolvingthetranscendentalequation supersoniccutoffwavenumber.Eachschemeisassessedbycomparingits in a designated frequency range. Data are attained over a broadband of predictions to the convergent SVP solution. For the nonsymmetric azi- frequenciesandtemperatureswithoutdependenceonthetime-temperature muthal harmonics, the field quantities and the radiated power are well superpositionprinciple. predictedifsubsonicwavesareignored.Incontrast,fortheaxisymmetric component, substantial errors (cid:126)6 dB or more(cid:33) for radiated power arise, unlessabroadspectrumofsubsonicwavesareincludedintheformula- 10:00 tion. The power is mostly reactive, being associated with an evanescent 1aSA9. A combined experimental and numerical method for field,evenforthesupersonicspectrum.Thestudyshowsthatsmallinter- computing sound radiation from underwater vibrating structures. actions between subsonic waves in the axisymmetric case can result in John B. Fahnline, Matthew J. Erickson, Dean E. Capone, Stephen A. substantialradiativeeffectsthatarenotmodeledinraytheoryanalyses. Hambric,andCourtneyB.Burroughs (cid:126)Appl.Res.Lab.,PennStateUniv., 16AppliedScienceBuilding,UniversityPark,PA16804(cid:33) 11:00 Underwatermeasurementsoftheradiatedsoundpowerfromavibrat- 1aSA12. Does the Rayleigh–Ritz method for vibratory continuous ingstructureareconventionallyperformedeitherbydirectmeasurements systems actually converge to the analytical eigensolution? Jerry H. inalargebodyofwaterorbyreverberationmeasurementsinawatertank. Ginsberg (cid:126)G. W. Woodruff School of Mech. Eng., Georgia Inst. of Both methods have inherent drawbacks. Direct measurements in a large Technol.,Atlanta,GA30332-0405(cid:33) bodyofwaterrequirealargescaleoperationandarerelativelyexpensive. Reverberation measurements are only accurate at high modal densities, The Rayleigh–Ritz method for continuous systems uses an N-term and thus a very large tank is required to obtain accurate low-frequency series with unspecified coefficients as the trial function for the Rayleigh predictions. To avoid both difficulties, a hybrid approach has been de- ratio. Extremizing that ratio leads to N approximate natural frequencies vised. Experimental measurements of the vibrations of the structure are (cid:118)(N), j(cid:53)1,...,N.Theupperboundtheoremstatesthatthetruevaluesob- j takeninawatertankusingascanninglaserDopplervibrometer,wherethe tainedbysolvingthefieldequationsaresuchthat(cid:118)(cid:60)(cid:118)(N). Thesepara- j j laserbeamisshoneontothesubmergedstructurethroughanopticalqual- tiontheoremstatesthataddingasingletermtotheaforementionedseries itywindow.Thesurfacevibrationdataarethenusedtoderivethespeci- yields new estimates (cid:118)(N(cid:49)1), j(cid:53)1,...,N(cid:49)1, such that the previous (cid:118)(N) j j fied normal velocity for a numerical calculation of the radiated sound fallintheintervalsbetweenthenewvalues.Takentogether,thesetheo- power radiated in free-field conditions. The laser allows dense surface rems constitute a proof that the lower eigensolutions obtained from the meshestobedefinedsuchthatthecalculationscanbeperformedtorela- Rayleigh–Ritz method should converge to the true eigensolution. How- 3067 J.Acoust.Soc.Am.,Vol.102,No.5,Pt.2,November1997 134thMeeting:AcousticalSocietyofAmerica 3067 Downloaded 11 Jul 2013 to 128.95.155.147. Redistribution subject to ASA license or copyright; see http://asadl.org/terms ever,boththeoremsassumeinfiniteprecisionarithmetic.Thispaperuses 11:30 the simple case of a cantilever beam to examine the behavior of the 1aSA14.Effectsoflaserstrokeparametersonquantitativevibration Rayleigh–Ritzmethodwithincreasingserieslength.Naturalfrequencies derivedfromdifferentclassesofkinematicallyadmissiblebasisfunctions, measurements with stroboscopic shearography. Benjamin A. Bard drawnfrommonomials,trigonometricfunctions,andBesselfunctionsare (cid:126)Appl.Res.Lab.,PennStateUniv.,P.O.Box30,StateCollege,PA16804, examinedrelativetotheupperboundandseparationtheorems.Mostse- [email protected](cid:33) lections fail to yield properly behaved solutions if the series length is extendedbeyond10–12terms.Insomecasestheeigenvaluesolverfailsto Digital shearography is a full-field speckle interferometric technique findrealeigenvalues,ortofindthecorrectnumberofeigenvalues.Some similartoelectronicholography.Traditionally,shearographyandhologra- ofthebasisfunctionsetspermitformulatingtheRayleighratiofunctional phyhavebeenusedforvibrationmeasurementwitheithertimeaveraged analytically, rather than by numerical integration, but the results are the orstroboscopictechniques.Timeaveragingimagessinusoidalmotionof same. The failure of the method is shown to stem from ill-conditioning an object’s surface over many periods of vibration, resulting in a fringe thatarisesasaconsequenceofsimilarityintheappearanceofhigher-order patternrepresentativeofthemagnitudeofthedisplacementmodeshape. basisfunctions. Stroboscopic illumination synchronizes short bursts, or strokes, of laser light with extrema of vibration. This essentially freezes motion of the 11:15 vibrating surface, allowing it to be studied with techniques normally re- 1aSA13. An overview of interaction between friction and vibrations. servedforstaticdeformation.Inparticular,phasestepping,anestablished AdnanAkay (cid:126)Mech.Eng.Dept.,CarnegieMellonUniv.,Pittsburgh,PA techniqueforcapturingaseriesofimagesandcalculatingtheexactdis- 15213(cid:33) placement at every point, can be applied to vibration measurement. If displacementamplitudescalculatedfromlaserstrobingandphasestepping Friction is a function of both the interface properties and dynamic aretobeusedformeasurementofpeakvibrationresponse,correctionsare responseofafrictionpair.Thetruecontactareaandthusthetotaltime- necessarytocompensateforerrorsduetothefinitedurationofthelaser dependent friction and normal forces change as a result of the relative motionofthesurfaceswithrespecttoeachother.Frictioninadynamic strokesaswellastheirimpropertimingduetosystemimpedance.Inthis systemhasthedualroleofbothexcitingvibrationsaswellasdissipating presentation,effectsofstrokedurationwillbeexpressedmathematically vibratory energy. In this presentation, mechanisms by which friction in- andtrendsdemonstratedexperimentally.Potentialsolutionsforstrokeoff- duces vibrations in dynamic systems are reviewed and the fundamental set correction will be discussed and experimental validation provided. issuesinvolvedinfrictionforcemodelingarediscussed. (cid:64)WorksponsoredbythePSUAppliedResearchLaboratory.(cid:35) MONDAY MORNING, 1 DECEMBER 1997 CALIFORNIA ROOM, 11:00 A.M. TO 12:30 P.M. Session 1aSC Speech Communication: Workshop: Basic Science at the Intersection of Speech Science and Communication Disorders Lynne E. Bernstein, Cochair Spoken Language Processing Laboratory, House Ear Institute, 2100 West Third Street, Los Angeles, California 90057 Gary Weismer, Cochair Waisman Center, University of Wisconsin, 1500 Highland Avenue, Madison, Wisconsin 53705 11:00 1aSC1. Chair’s introduction to the workshop on basic science at the intersection of speech science and communication disorders. LynneE.Bernstein (cid:126)SpokenLang.ProcessesLab.,HouseEarInst.,2100WestThirdSt.,LosAngeles,CA90057(cid:33)and GaryWeismer (cid:126)Univ.ofWisconsin,Madison,WI53705(cid:33) Inthestudyofspeechperceptionandproduction,thereisahistoryofdeveloping,evaluating,andrevisingmodelsandtheories based on data collected exclusively from talkers and listeners judged to be free of communication disorders. Basic research with clinically relevant disorders is sometimes confused with, and dismissed as, clinical/applied research. In other branches of science, including, for example, psycholinguistics and biology, study of clinical disorders is regularly employed as one of the avenues for building and testing more comprehensive theories and/or models, and is viewed as a major source of knowledge concerning the physiologicalstructuresresponsiblefornormalprocesses.Theintentoftheworkshopformatistoprovideaforumfordiscussionof thesignificanceofclinicaldisordersforthescientificareasofspeechperceptionandproduction.Agroupofdistinguishedscientists hasbeeninvited:(cid:126)1(cid:33)todescribetheirownworkinvolvingdisordersinspeechproductionand/orperception;and(cid:126)2(cid:33)tocommenton scientific, data analytic, philosophical, and pragmatic issues that are specific to the enterprise of incorporating data from clinical disordersintotheirworkandtheirfields.Theorganizersencouragetheattendanceofscientistswithandwithoutresearchinvolving clinicaldisorders,aswellasstudents. 3068 J.Acoust.Soc.Am.,Vol.102,No.5,Pt.2,November1997 134thMeeting:AcousticalSocietyofAmerica 3068 Downloaded 11 Jul 2013 to 128.95.155.147. Redistribution subject to ASA license or copyright; see http://asadl.org/terms MONDAY AFTERNOON, 1 DECEMBER 1997 EL CAMINO/ADOBE ROOMS, 1:25 TO 3:50 P.M. Session 1pAO Acoustical Oceanography: Acoustic Observations of Ocean Ridge Processes Christian P. de Moustier, Chair Marine Physical Laboratory, Scripps Institution of Oceanography, 9500 Gilman Drive, La Jolla, California 92093-0205 M P Chair’sIntroduction—1:25 N. O Special Lecture M p 1 1:30 1pAO1.Underwateracousticsforseafloorgeodesy. FredNoelSpiess (cid:126)MarinePhysicalLab.,SIO,UCSD,9500GilmanDr.,La Jolla,CA92093-0205(cid:33) Geodetic data, particularly using electronic distance measuring and space-based techniques, are central to terrestrial studies of crustaldeformation.Adecadeago,nocomparablecapabilitiesexistedforuseintheEarth’sextensiveocean-coveredareas.Ithad been clear for some time, however, that underwater acoustics could play a key role, replacing or extending the electromagnetic methodsusedinnearlyallterrestrialsystems.Threeclassesofcentimeter-capablesystemshaveemerged.Forshortranges,directpath measurementsusinghighfrequenciesarepreferred.Atintermediateranges(cid:126)1–10km(cid:33)markertransponderscanbeinterrogatedfrom an intermediate vehicle and their relative positions calculated. Beyond about 10 km, inadequate knowledge of sound speed limits purelyacousticsystems,butacombinedGPS/acousticmethodhasbeendevisedtocopewiththeneedfordataoverimportantlonger baselines.Since1990,severalsystemshavebeenimplementedinthecontextofgeologicallyrelevantproblems,particularlyinthe northeastPacific.Asoperatingexperiencehasgrownandrealdataarebeinganalyzed,usefulinitialresultsareemerginginconjunc- tionwithinsightsintotheproblemsthatmustbesolvedwhenmovingtowardfuturedevelopments.(cid:64)Workreportedhasbeensupported byNSF,NASA,NOAA,PGC,andUSGS.(cid:35) Contributed Papers 2:00 2:15 1pAO2. Possible seismic evidence for fluid migration at the eastern 1pAO3. Sonar observations of deep ocean hydrothermal flows. JuandeFucaRidgeflank. L.Zuehlsdorff,V.Spiess,andC.Huebscher Darrell R. Jackson, Christopher D. Jones, Timothy Wen (cid:126)Appl. Phys. (cid:126)Dept.ofGeosciences,Univ.ofBremen,Bremen,28334,Germany(cid:33) Lab., College of Ocean and Fishery Sci., Univ. of Washington, Seattle, Youngandpermeablecrustalongoceanicridgesisoftencharacterized WA98105(cid:33),PeterA.Rona,andKarenG.Bemis (cid:126)RutgersUniv.,New bylarge-scalefluidmigrationdependingonpermeabilityandheatdistri- Brunswick,NJ08903-0231(cid:33) bution.TheeasternflankoftheJuandeFucaRidgeoffthewestcoastof North America is buried under an unusual thick sediment cover and is Amechanicallyscannedsonaroperatingat330kHzhasbeenusedto thereforesuitablefordetailedstudiesonfluidexchangeprocesses.Inau- imagehydrothermalflowsonoceanridgesusingtwodifferenttechniques. tumn1996ahigh-resolutionseismicsurveywascarriedoutinthevicinity Scatteringfromparticulatesisusedtoimagesmokerplumes(cid:64)Ronaetal., ofODPLeg168drillsitestocollectdetailedinformationaboutsedimen- Geophys.Res.Lett.18,2233–2236(cid:126)1991(cid:33)(cid:35),andscintillationofseafloor tarystructuresandacousticanomaliesinrelationtobasementmorphology. backscatterisusedtoimagediffuseflows.Resultswillbepresentedfrom Theseismicequipmentwasoptimizedforhighlateralandverticalresolu- cruisesontheEastPacificRiseandthenorthernCleftsegmentoftheJuan tiontoidentifysmall-scalefeaturesfromthesurfacedowntothebasement aspotentialmigrationpathsforfluids.Theacquiredseismicsectionsex- de Fuca Ridge. Plume images have been analyzed to extract physical hibit numerous vertical zones with reduced reflection amplitudes which parametersrelevanttoplumetheory.Observationsofdiffuseflowemploy mayrepresentpathsforfluidadvection.Thelateralamplitudechangesare crosscorrelationofpingdoublets.Scatteringtheoryisusedtorelatethe visible using seismic sources with different frequency content and are correlationlevelstothevarianceoftemperaturefluctuations.(cid:64)Worksup- apparentlyrelatedtobasementtopography.Observationsonparallelpro- ported by the NOAA National Undersea Research Program through the filesindicatea2-Dgeometry.Theoreticalstudiessuggestthatlocalporos- WestCoastUnderseaResearchCenter.(cid:35) itychangesmaybethereasonfortheacousticvisibilityoftheproposed advectionzones. Invited Paper 2:30 1pAO4. Seismoacoustic recordings of a volcanic event on the Mohns Ridge, 1995. Donna K. Blackman and John A. Orcutt (cid:126)ScrippsInst.ofOceanogr.,LaJolla,CA92093-0225,[email protected](cid:33) AswarmofearthquakesoccurredonanoceanicspreadingcenternorthofIcelandinlate1995andwasrecordedbyU.S.Navy hydrophonearraysintheNorwegianSea.AbouttwodozenoftheseeventsontheMohnsRidgeweredetectedbyonshoreseismic arrays. Analysis of the hydrophone array data shows that 7000 events occurred; the greatest number (cid:126)40/h(cid:33) took place in a 3-day periodinthemiddleofthe70-daydurationoftheswarm.RecordedarrivalsincludePwaves,water-borneTwaves,PTpairs,andP wavesreflectedattheseasurface.SeparationinarrivaltimesofPandTwavesareusedtodeterminerelativelocationsofeventsand 3069 J.Acoust.Soc.Am.,Vol.102,No.5,Pt.2,November1997 134thMeeting:AcousticalSocietyofAmerica 3069 Downloaded 11 Jul 2013 to 128.95.155.147. Redistribution subject to ASA license or copyright; see http://asadl.org/terms their spatial evolution throughout the swarm. The locus of activity shifts by 30–40 km during the swarm but steady migration of activityisnotapparent.Thissuggeststhatsurfacebreaksduringdikeinjectiondidnotoccuror,atleast,didnotgenerateTwaves,or thattheswarmwasnotassociatedwithasimpledikeemplacementalongtheridge.Thetimehistoryoftheactivity,ontheotherhand, isquitesimilartothatseenassociatedwithtwoknownvolcaniceventsontheJuandeFucaandGordaridges. Contributed Papers 2:50 3:20 1pAO5. Earthquake studies using under-ice hydrophone data 1pAO7.Implicationsofnonfractalseafloorstochasticityonacoustical (cid:132)‘‘Spinnaker’’(cid:133). RobertA.Sohn,JohnA.Hildebrand (cid:126)ScrippsInst.of scatteringfromtheMid-AtlanticRidge. VincentLupienandArthurB. Oceanogr., 8602 La Jolla Shores Dr., La Jolla, CA 92093-0205, Baggeroer (cid:126)MIT,Cambridge,MA02139(cid:33) [email protected](cid:33),andBarbaraJ.Sotirin (cid:126)NavalCommand,SanDiego, AcousticalandbathymetricdatawerecollectedneartheMid-Atlantic CA92152(cid:33) RidgeaspartoftheAcousticalReverberationSpecialResearchProgram Preliminary studies indicate that the Spinnaker array, a network of (cid:126)ARSRP(cid:33)in1993.Thewidebandtime-domainenvelopestatisticsofback- hydrophones currently deployed in the Arctic Ocean, may be used to scatterfromprominentbathymetricfeaturesexhibitanon-Rayleighchar- monitorseismicityoftheArcticBasin,aswellaslongdistanceteleseismic acterwhichpreviousresearchershavedescribedasevent-like.Theenve- arrivalsfromtheSouthernHemisphere.TheArcticBasinisatectonically lope probability density functions (cid:126)pdf’s(cid:33) show enhanced tails at high complexregionthathasseenfewseismicstudies,andtheSpinnakerarray levelswhichcanbeasourceofactivesonarclutter.Itisproposedthatthe hasthepotentialtomonitorsomeofitsmostinterestingfeatures,suchas originofsuchclutterissingle-scale,nonfractalroughness.High-resolution theNansen–GekkelRidge(cid:126)theslowestspreadingridgeintheworld(cid:33),in bathymetryrevealsapowerspectraldensity(cid:126)PSD(cid:33)withpower-lawform. near real time. In addition, teleseismic arrivals at the array may have Waveletanalysesrevealasingle-scalecharactertotheroughness.Inorder raypathsthatcoincidecloselywiththeEarth’sspinaxis.Thesedatamay totestthehypothesis,multiscaleandsingle-scalerealizationsofthemea- proveusefultocurrentstudiesofthecrystallinealignmentanddifferential suredPSDsareusedinnumericalsimulationsoftime-domainbackscatter. spinoftheEarth’sinnercore. At the range and azimuthal resolutions in the experiment, the envelope pdfsformultiscalesurfacesareRayleigh,whilethesingle-scalesurfaces leadtoenhancedtailsasobservedinthedata.Theconclusionsdrawnare that along with an interface’s rms height, correlation length, and power spectralshape,oneshouldalsobeconcernedwithitsscalestructurebe- cause it plays an important role in the physics of wave interaction at randominterfaces. 3:05 3:35 1pAO6. Locating ridge seismicity near Ascension Island using 1pAO8. Fractals, wavelets, and stochastic interface modeling. hydroacousticandseismicdata. JeffreyA.HansonandHollyK.Given VincentLupien (cid:126)MIT,Cambridge,MA02139(cid:33) (cid:126)Inst.ofGeophys.andPlanetaryPhys.,UCSD,LaJolla,CA92093(cid:33) Theseafloorisoneofmanynaturalinterfaceswhich,whenviewedas Recently,therehasbeenasurgeofinterestinmonitoringsmall-scale, a random process, exhibits a power law decay, i.e., the power spectral mid-oceanridgeseismicityasmadepossiblebytheincreasingavailability density (cid:126)PSD(cid:33) decays as A/fb, A(cid:46)0, b(cid:46)0 as f!(cid:96). Power law spectra ofdatafrommilitary-runhydrophonearrays.Inthepast,long-termridge areusuallytakenasevidencethatthestochasticprocessismultiscaleor seismicityhasbeenstudiedusingtheglobalnetworksofseismicstations. fractal.Multiscaleinterfacesexhibitfeaturesatallscalesandtheiracous- Sincetheyounglithosphereattheridgeisrelativelyweak,itisnotableto tical properties are distinct from those of single-scale interfaces, which supportlargeearthquakesandmuchoftheseismicityassociatedwithac- containfeaturescloselyclusteredaboutameansize.Thus,determination tive deformation is not detected by the seismic networks. In addition to of the scale structure, or size distribution of component features, is im- seismic body waves, mid-ocean ridge earthquakes usually produce a T portant in characterizing random interfaces for acoustical applications. phase—awater-borneacousticwave—whichtravelsgreatdistanceswith However, because the PSD is only a second moment characterization, a littleattenuationandiswellrecordedbyhydrophones.Thispaperexam- power law PSD can allow both single-scale and multiscale processes. inesearthquakesfromasectionoftheMid-AtlanticRidgenearAscension OnlyiftheprocessisGaussianisthePSDacompletedescription.Wave- Island, using data collected from five U.S. Air Force hydrophones that letrepresentationssucceedwhereFouriermethodsfail,astheyareideally surroundtheislandandtheseismicstationASCNlocatedontheisland. suitedfordeterminingscalestructure.Inthecaseoffractalinterfaces,the ByintegratingthehydroacousticTphaseandthelocalbody-wavephases, waveletcoefficientsareGaussianandindependentacrossscaleandspace. earthquakescanbelocateddowntoamagnitudeof2.8onasegmentof Single-scaleinterfacesleadtoadependenceofwaveletcoefficientsacross theridgewithanaccuracyofabout5km. scaleforagivenspatiallocationandvice-versa. 3070 J.Acoust.Soc.Am.,Vol.102,No.5,Pt.2,November1997 134thMeeting:AcousticalSocietyofAmerica 3070 Downloaded 11 Jul 2013 to 128.95.155.147. 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