Second Harmonic Generation in Sound Beams Reflected from and Transmitted through Immersed Elastic Solids*

Wednesday, April 2, 1997 3:00 p.m. Brian J. Landsberger Department of Mechanical Engineering The University of Texas at Austin http://www.me.utexas.edu This seminar reports a theoretical and experimental investigation of finite amplitude sound beams reflected from, and transmitted through,  isotropic elastic solids immersed in liquids.  Attention  is focused  on the fundamental  and nonlinearly generated second harmonic…

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Acoustic Seminars

Experimental Studies with N Waves from Sparks

Friday, March 28, 1997 4:00 p.m. Professor Wayne M. Wright Department of Physics Kalamazoo College Kalamazoo, Michigan Weak sparks in air can be used to generate intense, short-duration acous­tic transients that resemble N waves. Measurements made with wide-band capacitor microphones have confirmed theoretical predictions of amplitude decay and waveform elongation with propagation distance. These waves…

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Acoustics Seminars

Noise Control and Engineering Acoustics at Boeing

Monday, March 3, 1997 4:00 p.m. Dr. Milton Lumpkin Manager, Noise Engineering 737/757 Programs Boeing Corporation Seattle, Washington http://www.boeing.com At Boeing, the Noise Engineering and Noise Laboratory organizations em­ploy approximately 160 people to insure that Boeing aircraft set world class standards for low noise emissions. Our scientists, engineers, and technicians work to reduce the noise…

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Acoustics Seminars

Mode Extraction from a VLA Using Singular Value Decomposition

Friday, February 21, 1997 4:00 p.m. Tracianne Neilsen Department of Physics The University of Texas at Austin http://www.ph.utexas.edu A method is developed for extracting the depth-dependent mode functions from single-frequency measurements on a vertical line array as a source moves out in range. A matrix of the complex pressure field versus receiver depth and source…

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Acoustics Seminars

Review of Recent and Ongoing Developments in the Acoustic Treatment of Aerosols

Friday, January 31, 1997 4:00 p.m. Karl Martin Department of Mechanical Engineering The University of Texas at Austin http://www.me.utexas.edu Acoustic agglomeration is the use of high intensity sound to cause aerosol particles to stick together. It is a process with applications in pollution control and bulk materials handling. The acoustic agglomeration effect has been known…

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Acoustics Seminars

Control of Acoustic Cavitation with Application to Lithotripsy*

Wednesday, December 18, 1996 3:00 p.m. Mike Bailey Department of Mechanical Engineering Control of acoustic cavitation, which is sound-induced growth and collapse of bubbles, is the subject of this dissertation. Application is to extracorporeal shock wave lithotripsy (ESWL), used to treat kidney stones. Cavitation is thought to help comminute stones yet may damage tissue. Can…

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Acoustics Seminars

Presentations for the Third Joint ASA Meeting Honolulu, Hawaii

Monday, November 25, 1996 4:00 p.m. Frank Boyle Applied Research Laboratories: A Generalized Acoustic Model for Marine Sediments Matias Budhiantho Department of Electrical Engineering: Acoustic Velocity Related Statistical Distributions B. J. Landsberger Department of Mechanical Engineering: Second Harmonic Generation in a Sound Beam Transmitted Through an Isotropic Solid Zhenia Zabolotskaya Department of Mechanical Engineering: Nonlinear…

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Acoustics Seminars

Propagation of Acoustic Pulses in a Turbulent Medium

Friday, November 15, 1996 4:00 p.m. Dr. Philippe Blanc-Benon Laboratoire de M’ecanique des Fluides et d’Acoustique Ecole Central de Lyon Lyon, France An acoustic wave propagating through a turbulent atmosphere is significantly affected by the variation in the value of the refractive index along the propagation path. The influence of temperature and wind velocity fluctuations…

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Acoustics Seminars

Point-Source Reciprocity Relations in Elastodynamics and Acoustics

Monday, November 11, 1996 4:00 p.m. Professor C. L. Morfey Institute of Sound and Vibration Research Southampton, United Kingdom The fields of linear elastodynamics and linear acoustics employ somewhat different reciprocity relations for the limiting case of point sources. In acoustics, the volume-velocity source is regarded as basic: The appropriate reciprocity relation is well-known and…

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Acoustics Seminars

Localization and Delocalization in One-Dimensional Dynamic Systems

Wednesday, November 6, 1996 4:00 p.m. Joe Dickey The Johns Hopkins University Mechanical structures with reasonably periodic variations in impedance may exhibit wave localization similar to Anderson localization in atomic systems. Several such systems have been investigated by the authors: a beaded string, membranes and plates with periodic stiffeners attached, and a “jungle gym” All…

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Acoustics Seminars

Acoustical Aspects of the Planar Jet Instability

Friday, November 1, 1996 4:00 p.m. Dr. A. Wilson Nolle Department of Physics The spatial growth of the sinuous instability of planar jets has received much attention as the amplification mechanism involved in edge-tone oscillation and in flutelike instruments. Early “temporal” theoretical treatments, used in most discussions of these systems, dealt with an unrealistic oscillation…

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Acoustics Seminars

Modeling and Measurement of Nonlinear Surface Waves*

Monday, October 14, 1996 3:30 p.m. Doug Meegan Applied Research Laboratories The linear theory for small-signal surface waves (Rayleigh, Scholte, and Stoneley) will be reviewed, and conditions for the existence of these modes of propagation will be described. Next, a nonlinear theory for finite-amplitude Stoneley and Scholte waves will be presented. The theory generalizes an…

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Acoustics Seminars

Lithotripsy: The Breaking of Kidney Stones by Acoustic Shock Waves

Friday, October 4, 1996 4:00 p.m. Dr. Robin Cleveland Applied Physics Laboratory University of Washington at Seattle The use of shock waves to destroy kidney stones has found wide acceptance in hospitals throughout the world. Although over two million successful lithotripsy treatments have occurred, there is still much to be learned about the physical mechanisms…

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Acoustics Seminars

Trends in Electromechanical Transduction

Wednesday, September 11, 1996 4:00 p.m. Dr. Ilene Busch- Vishniac Department of Mechanical Engineering In recent years there has been a growing interest in electromechanical trans­ducers, i.e., sensors and actuators. This increase in interest has been prompted by a number of trends, including: the growing pervasiveness of sensors and in­telligence in devices, the increasingly challenging…

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Acoustics Seminars

Presentations for the 131st Meeting of the Acoustical Society of America

Monday, May 6, 1996 3:30 p.m. Michael R. Bailey “Intensified cavitation produced with pressure release and rigid ellipsoidal reflectors” E. A. Zabolotskaya “Nonlinear surface wave propagation in crystals” David T. Blackstock “R. T. Beyer’s contributions to nonlinear acoustics” Frank A. Boyle “Mapping acoustic echosounder data to human color vision” Penelope Menounou “Propagation of finite-amplitude broadband…

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Acoustics Seminars