Monday, October 10, 1988 1:00 p.m. Akira Nakamura Oska University Oska, Japan As is well known, the nonlinear distortion of finite amplitude sound results from the fact that propagation speed depends on particle velocity and the nonlinearity parameter of the medium. In the case of a thin fiber of fused silica, the waveform of a…
Wednesday, October 5, 1988 1:00 p.m. Jack Leifer Department of Mechanical Engineering The University of Texas at Austin An acoustical system is being developed for use as a highly accurate positioning device in robotics applications. The system includes a high frequency, omnidirectional ultrasonic source, and a number of PVDF based pick-up microphones. This seminar will…
Wednesday, September 28, 1988 1:00 p.m. Professor Ilene Busch-Vishniac Department of Mechanical Engineering The University of Texas at Austin Circuit models of transducers have been used for decades, and have proven to be useful tools for prediction of transducer behavior. In this approach the transduction mechanism is typically modeled using ideal two-port transformers or gyrators…
Wednesday, September 21, 1988 1:00 p.m. Another professionally taped video on pipe organs. This time we follow the design and construction of a single organ from start to finish. It is a French-style ‘tracker’ organ built by the Bedient Organ Co, Lincoln Nebraska, and installed in St. Mark’s Episcopal Church, Grand Rapids, Michigan. Prof. Wilson…
Wednesday, September 14, 1988 1:00 p.m. Professor Mark F. Hamilton Department of Mechanical Engineering The University of Texas at Austin A report will be given on the author’s trip last month to acoustics institutes in Moscow, Leningrad, and Tallinn. The seminar will consist of a slide show, a discussion of research performed at the various…
Wednesday, May 4, 1988 1:00 p.m. Dr. Charles R. Ervin Violin Maker and Restorer Austin, TX Dr. Ervin, a fine stringed instrument maker who lives in Austin, has developed a method of plate thinning which can improve even a very good sounding violin. He will give a short presentation and slideshow on how a violin…
Wednesday, April 27, 1988 1:00 p.m. David E. Edmonds Department of Mechanical Engineering The University of Texas at Austin Knowledge of the dynamic compressibility (βD) of organic solids used in sonar transducers is important if the transducers are built to operate at a wide range of depths, pressures, and frequencies. Measuring βD(p, T, ƒ) has…
Wednesday, April 20, 1988, 1:00 p.m. A. Wilson Nolle Department of Physics The University of Texas at Austin A closed-loop system in which several simple oscillators are driven by a single saturable element is considered. This element is in turn excited by the summed oscillator velocities. Oscillation is started by increasing the loop gain in…
Wednesday, April 13, 1988 1:00 p.m. Henry M. Paynter Professor Emeritus and Senior Lecturer Massachusetts Institute of Technology and Adjunct Professor, The University of Texas at Austin Wave-scattering formalism deals with the operators which relate incoming particles or waves to outgoing particles or waves subjected to scattering obstacles or events. Introduced 50 years ago to…
Wednesday, April 6, 1988 1:00 p.m. Ola Michael Vestavik Department of Petroleum Engineering The University of Texas at Austin When drilling for petroleum resources, formation fluids may enter the well and lead to serious problems including disastrous blowouts. In order to reduce this danger, improved techniques for detection of gas in the well must be…
Wednesday, March 30, 1988 1:00 p.m. A professionally edited video program shows the general construction of a pipe organ and the fabrication and voicing of the pipes. The relationship between the pipe shape and the acoustic spectrum is also illustrated. Professor Wilson Nolle of the Physics Department will add a few comments on this aspect.
Wednesday, March 23, 1988 1:00 p.m. C. L. Morfey Institute of Sound and Vibration Research University of Southampton, England Progress will be reported on the problem of modeling the sound field produced by an extracorporeal shock wave lithotripter. This is a device now in routine clinical use for noninvasive fragmentation of kidney stones. It operates…
Wednesday, March 9, 1988 1:00 p.m. Dr. David T. Blackstock Department of Mechanical Engineering Applied Research Laboratories and The University of Texas at Austin An operational definition of absorption α= -∇ ·I/2I, where I is the sound intensity, was popular in the 1950’s as a means of quantifying the increased attenuation of finite-amplitude ultrasonic beams.…
Monday, March 7, 1988 12:00 p.m. Evan Westwood Department of Electrical Engineering and Applied Research Laboratories The University of Texas at Austin A new method based on ray theory for modeling acoustic propagation in shallow water environments will be presented. While classical ray theory is a high-frequency approximation which is not valid in shallow water,…
Wednesday, March 2, 1988 1:00 p.m. Corinne Darvennes Department of Mechanical Engineering The University of Texas at Austin The generation of difference frequency sound by two beams that interact at a nonzero angle is referred to as scattering of sound by sound. Whether the difference frequency sound can be radiated outside the noncollinear interaction region…
Wednesday, February 24, 1988 1:00 p.m. Keith Lent Department of Electrical Engineering and Department of Music The University of Texas at Austin During the past twenty five years a number of technological advances have made it possible for a musician to digitally synthesize compositions. This is usually done within the framework of a general purpose…
Monday, February 15, 1988 1:00 p.m. Dr. Steven Garrett Department of Physics Naval Postgraduate School Monterey, California The Space Thermoacoustic Refrigerator (STAR) is currently under development at the Naval Postgraduate School. This novel cryocooler uses resonant sound waves in a He/Xe gas mixture to pump heat at high efficiency without the use of sliding seals…
Wednesday, February 10, 1988 1:00 p.m. Dr. Linda Thibodeau Department of Speech Communication The University of Texas at Austin One explanation for the speech recognition difficulties of hearing-impaired persons with sensorineural hearing loss is a reduction in their ability to differentiate spectral information. A proposal for how this inability relates to speech recognition will be…
Friday, February 5, 1988 1:00 p.m. Dr. Tom Griffy Department of Physics Applied Research Laboratories and The University of Texas at Austin Measurements of ambient acoustic noise in the atmosphere have been limited to a few meters from the ground. In August of 1987, a hot air balloon was used as a platform to measure…
Wednesday, January 27, 1988 1:00 p.m. Steve Morriss Department of Petroleum Engineering The University of Texas at Austin The objective of this project is to determine the feasibility of using ultrasonic techniques to measure fluid velocities and to create images of the phase distribution in multiphase flow. The measurement system is based on a commercial…