1997 Bernstein, Chair's introduction to the workshop on basic science at the intersection of speech science and communication disorders.pdf (PDFy mirror)

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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
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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
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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
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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
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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
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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. Redistribution subject to ASA license or copyright; see http://asadl.org/terms