Friday, February 2, 2001 4:00 p.m. Dr. Nicholas P. Chotiros Applied Research Laboratories The University of Texas at Austin http://www.arlut.utexas.edu An inversion of the Biot model using measured acoustic properties suggests a modification of the Biot-Stoll equations as they apply to the propagation of sound in water saturated sand. The Biot model of sound propagation…
Friday, January 26, 2001 4:00 p.m. Antonios Apostolou Graduate Program in Acoustics Pennsylvania State University, and Schlumberger Oilfield Services http://www.acs.psu.edu http://www.psu.edu http://www.slb.com/oilfield/index.cfm?id=id4638 When a drop of a liquid impacts onto a liquid surface, a crater is formed and the cavity dynamics that follow determine whether or not a bubble will be entrained. The entrainment of…
Tuesday, November 28, 2000 4:00 p.m. Dr. Philippe Blanc-Benon Ecole Centrale de Lyon Lyon, France The knowledge of temperature and flow fields in the microchannels and at the edges of the stack plates becomes an increasingly important issue in the design of heat exchangers for thermoacoustic engines. On these topics we have conducted experiments in…
Wednesday, November 15, 2000 4:00 p.m. Assistant Professor Philip Loizou Department of Electrical Engineering The University of Texas at Dallas Dallas, Texas http://www.utdallas.edu/dept/ee Cochlear implants are now established as a new option for individuals with profound (sensorineural) hearing impairment. Many of the cochlear implant patients are able to understand speech without lip-reading, and some can…
Monday, November 13, 2000 4:00 p.m. Dr. D. Keith Wilson U.S. Army Research Laboratory Adelphi, Maryland http://www.arl.army.mil/main/Main The surface layer of the atmosphere (roughly the lowermost 50 to 100 m) is characterized by vigorous turbulence and sharp vertical gradients in the wind speed and temperature. These phenomena affect sound propagation near the ground in complex…
Friday, November 3, 2000 4:00 p.m. Professor C. L. Morfey Institute of Sound & Vibration Research University of Southampton Southampton, UK http://www.soton.ac.uk Transverse oscillations of a cylinder in a viscous fluid generate a force on the fluid that becomes nonlinear at large oscillation amplitudes. When the cylinder motion is sinusoidal, nonlinearity produces odd-order harmonic distortion…
Friday, October 27, 2000 4:00 p.m. Dr. Tom D. Kite Audio Precision Beaverton, Oregon http://audioprecision.com At the 108th AES convention in February 2000, Angelo Farina of the University of Parma presented a paper entitled “Simultaneous measurement of impulse response and distortion with a swept-sine technique”. The paper shows how to use a logarithmically-swept sine FM…
Friday, October 20, 2000 4:00 p.m. Dr. Terry L. Henderson Applied Research Laboratories The University of Texas at Austin http://www.arlut.utexas.edu At the 108th AES convention in February 2000, Angelo Farina of the University of Parma presented a paper entitled “Simultaneous measurement of impulse response and distortion with a swept-sine technique”. The paper shows how to…
Friday, October 13, 2000 4:00 p.m. Dr. G. Douglas Meegan Applied Research Laboratories The University of Texas at Austin http://www.arlut.utexas.edu No abstract available.
Friday, October 6, 2000 4:00 p.m. Washington De Lima Department of Mechanical Engineering The University of Texas at Austin http://www.me.utexas.edu This seminar describes a theoretical approach to modeling harmonic generation associated with the propagation of finite-amplitude elastic waves in homogeneous, isotropic plates and rods. Solutions of the nonlinear equations of motion for harmonic generation in…
Friday, September 29, 2000 4:00 p.m. Joe Norris American Technology Corp. San Diego, California http://www.atcsd.com This presentation will cover the inherent difficulties associated with the Parametric Array in Air implementation, and explore recent developments in transducer design and signal processing techniques designed to maximize the available performance of a practical system. A demonstration unit will…
Friday, September 22, 2000 4:00 p.m. Dr. E. A. Zabolotskaya & Dr. Y. Ilinskii Department of Mechanical Engineering The University of Texas at Austin http://www.me.utexas.edu Recent advances in the development of thermoacoustic engines and acoustical compressors require an understanding of extremely intense sound fields (acoustic Mach numbers of order one) in resonators that are not…
Friday, May 5, 2000 4:00 p.m. Dr. Masao Kimura Tokai University Shizuoka, Japan http://www.u-tokai.ac.jp (1) Shear wave velocity measurements using radiation impedance. Shear wave velocity is important in characterizing surficial marine sediments. It was demonstrated that the shear wave velocities in viscoelastic media can be determined from the frequency at which the radiation reactance becomes…
Thursday, April 27, 2000 4:00 p.m. Dr. David C. Swanson Pennsylvania State University State College, Pennsylvania http://www.psu.edu Bending waves on a mid-way notched steel band under constant tension are monitored during many hours of transverse vibration excitation until the band breaks due to crack growth across the notched area. The crack growth is experimentally observable…
Monday, April 17, 2000 4:00 p.m. Dr. Oleg A. Sapozhnikov Moscow State University Moscow, Russia http://www.phys.msu.su Intense ultrasound is a promising therapeutic tool. Focused shock pulses are a way to obtain very high (up to 100 MPa) acoustic pressures locally inside the human body and are now clinically used to comminute kidney stones (extracorporeal shock…
Friday, April 14, 2000 4:00 p.m. Ender Kuntsal International Transducer Corporation Santa Barbara, California http://www.itc-transducers.com Designing an underwater electroacoustic transducer involves a unique combination of engineering disciplines including acoustical, electrical, mechanical and materials science. Transducer performance specifications, although different for almost every application, typically include stringent specifications such as transmit/receive response, efficiency, beam pattern, impedance,…
Friday, March 31, 2000 4:00 p.m. Kevin Cunningham Department of Mechanical Engineering The University of Texas at Austin http://www.me.utexas.edu Time reversal of sound waves permits the realization of systems which automatically retarget energy on scattering sites insonified by an incident probe beam. The self-targeting occurs despite the presence of inhomogeneities that may be present in…
Friday, March 24, 2000 4:00 p.m. Robert Tupper Custom Designs, Ltd. Boerne, Texas Line-source and speaker arrays have intrinsic properties that render them more suitable than conventional point-source radiators. From the standpoints of psychoacoustics and sound quality, these properties include radiation patterns that minimize both the spatial and timbral distortions introduced by point-source devices. Development…
Friday, March 10, 2000 4:00 p.m. Dr. Greg L. Wojcik Weidlinger Associates Los Altos, California http://www.weidlinger.com Until recently, acoustic transducer designers relied almost exclusively on one-dimensional (1D) semi-analytical models and experimental prototypes. Now, many employ virtual prototyping, i.e., comprehensive computer simulations of 2D and 3D transducer devices. Effectiveness of virtual prototyping depends on five factors:…
Friday, March 3, 2000 4:00 p.m. Dr. Paul A. Meyer Krautkramer Branson Lewistown, Pennsylvania http://www.geinspectiontechnologies.com The use of ultrasonic nondestructive inspection is well known. Critical components in power generating stations, aerospace vehicles, and chemical plants undergo regular inspections to determine suitability for continued service. Originally, inspections were conducted by an operator who manually scanned a…