• Volume/Page
  • Keyword
  • DOI
  • Citation
  • Advanced
   
 
 
 

Journal of the Acoustical Society of America

BROWSE VOLUMES

Year Range: 
Search Issue | RSS Feeds RSS
Previous Issue

Dec 1984

Volume 76, Issue 6, pp. 1609-1883

Page 2 of 5 Pages Previous Page Next Page | Jump to Page

On the drag and virtual mass coefficients in Biot’s equations

A. Bedford, R. D. Costley, and M. Stern

J. Acoust. Soc. Am. Volume 76, Issue 6, pp. 1804-1809 (1984); (6 pages) | Cited 2 times

Full Text: | Download PDF

Show Abstract
If the solid constituent of a fluid saturated porous medium is assumed to be subjected to a uniform oscillatory motion, Biot’s equations can be solved for the drag and virtual mass coefficients in terms of the resulting oscillatory motion of the fluid. The determination of these coefficients is therefore reduced to the solution of a boundary value problem for a viscous, compressible fluid. As an example, the pores have been assumed to be cylindrical. The motion of the fluid has been determined theoretically by subjecting the wall of a cylinder of viscous compressible fluid to a uniform oscillatory motion and averaging the resulting fluid displacement over the volume of the cylinder. Motions parallel to and normal to the axis of the cylinder have been considered. In the case of motion parallel to the cylinder axis, the obtained coefficients are equivalent to those obtained by Biot and by Hovem and Ingram. By superimposing the parallel and normal cases, the coefficients for cylindrical pores at an arbitrary angle to the propagation direction have been obtained. Then by averaging with respect to the angle, the coefficients have been determined for a material containing pores of random orientation.
Show PACS
43.30.Es Velocity, attenuation, refraction, and diffraction in water, Doppler effect
47.56.+r Flows through porous media
43.35.Bf Ultrasonic velocity, dispersion, scattering, diffraction, and attenuation in liquids, liquid crystals, suspensions, and emulsions
43.20.Bi Mathematical theory of wave propagation

A statistical approach to determining the number density of random scatterers from backscattered pulses

Paul Wilhelmij and Philip Denbigh

J. Acoust. Soc. Am. Volume 76, Issue 6, pp. 1810-1818 (1984); (9 pages) | Cited 1 time

Full Text: | Download PDF

Show Abstract
This paper describes a method of using the statistical character of the waveform backscattered from random scatterers to estimate the scatterer number density. The moments of the probability density function of the backscattered intensity depend on the scatterer number density. Expressions exist for these moments in terms of the number of scatterers contributing to the echo signal. These expressions can give an estimate for the scatterer number density, provided the resolution cell size of the backscattering configuration is known, and provided the number of scatterers in the resolution cell is small. This latter constraint is equivalent to a requirement that the statistics of the return signal envelope deviate significantly from a Rayleigh distribution. The validity of these expressions is investigated by analyzing the acoustic waveform backscattered from a randomized volume distribution of polystyrene spheres suspended in water when insonified by a short acoustic pulse. Experimentally, the second‐order moment of intensity is found to be given the most accurate predictions of number density. A specific application suggested for this work is acoustic fish‐stock assessment. Other possible applications are ultrasonic tissue characterization and acoustic ocean bottom identification.
Show PACS
43.30.Dr Hybrid and asymptotic propagation theories, related experiments
43.30.Ft Volume scattering
43.20.Fn Scattering of acoustic waves
43.60.Cg Statistical properties of signals and noise

Pulsed parametric array

D. H. Trivett and Peter H. Rogers

J. Acoust. Soc. Am. Volume 76, Issue 6, pp. 1819-1822 (1984); (4 pages)

Full Text: | Download PDF

Show Abstract
An earlier investigation [J. Acoust. Soc. Am. 71, 1114–1117 (1982)] of the nonlinear interaction of a freely propagating pulse with a cw plane wave is extended to encompass the pulsed parametric array. We find that a scattered signal at the difference frequency is received in the farfield only during the time that a signal is received from the stationary boundary (i.e., the interaction region directly in front of the transducer). Once the pulse appears to have left the face of the transducer in that no further signal is received from the stationary boundary, no further signal at the difference frequency is observed in the farfield. This results in an observed scattered signal that has a pulse length and arrival time consistent with direct radiation from the face of the transducer. However, the signal is found to be generated by a virtual endfire array with an effective length dependent upon the pulse length and observation angle. Experimental evidence is presented in support of these results.
Show PACS
43.25.Lj Parametric arrays, interaction of sound with sound, virtual sources

Radial extrapolation of wave fields by spectral methods

Sébastien M. Candel and Christian Chassaignon

J. Acoust. Soc. Am. Volume 76, Issue 6, pp. 1823-1828 (1984); (6 pages) | Cited 1 time

Full Text: | Download PDF

Show Abstract
Wave extrapolation methods are of considerable technological interest. When the wave field is axisymmetric or contains lower order azimuthal components, extrapolation may be performed in the radial direction from data recorded on a single sideline. This yields important reductions in the data acquisition and computation processes. This paper provides a theoretical basis for spectral‐domain radial extrapolation and describes numerical simulations and an experimental application.
Show PACS
43.20.Bi Mathematical theory of wave propagation
43.20.Rz Steady-state radiation from sources, impedance, radiation patterns, boundary element methods

Scattering of an acoustic Gaussian beam from a fluid–solid interface

John Pott and John G. Harris

J. Acoust. Soc. Am. Volume 76, Issue 6, pp. 1829-1838 (1984); (10 pages) | Cited 10 times

Full Text: | Download PDF

Show Abstract
The reflection and refraction at a fluid–solid interface of an acoustic beam, whose amplitude is Gaussian in cross section and which oscillates harmonically in time, is studied. The incident and scattered beams are constructed using the complex source‐point method. The incident beam is specularly reflected except at angles near one of the critical angles, of which the Rayleigh angle is the most important. Near this angle the beam excites both a leaky Rayleigh wave and a reflected beam, and the interference between these two disturbances produces the beam shifting noted by other workers. Surprisingly, a backward‐traveling leaky Rayleigh wave is also excited, although its amplitude is quite small. The incident beam, near normal incidence, is refracted into a compressional beam and a shear beam, both of whose amplitudes are Gaussian in cross section. Whereas the incident beam has a circularly shaped cross section, both transmitted beams have elliptically shaped cross sections. Moreover, the transmitted beams spread rapidly so that the compressional and shear beams always overlap. This rapid spreading limits the resolution of ultrasonic probes used to find cracks or other defects in a solid.
Show PACS
43.20.Bi Mathematical theory of wave propagation
43.20.Fn Scattering of acoustic waves
43.60.Cg Statistical properties of signals and noise

The T‐matrix approach for scattering by a traction‐free periodic rough surface

A. Lakhtakia, V. K. Varadan, V. V. Varadan, and D. J. N. Wall

J. Acoust. Soc. Am. Volume 76, Issue 6, pp. 1839-1846 (1984); (8 pages) | Cited 3 times

Full Text: | Download PDF

Show Abstract
A T matrix is formulated to characterize scattering by a traction‐free periodic rough surface and numerical results for several surface profiles are presented. The normalized reflected intensities are computed, for the cases of longitudinal (P) as well as shear (SV) wave incidence, as functions of the angle of incidence and frequency of the incident wave. The anomalous behavior of the reflected waves are explained in terms of their conversion from evanescent to propagating waves, as well as in terms of Rayleigh surface waves. Hybridization of the T‐matrix scheme with a point‐matching procedure is also discussed.
Show PACS
43.20.Fn Scattering of acoustic waves
68.35.Gy Mechanical properties; surface strains
68.35.Iv Acoustical properties
43.20.Bi Mathematical theory of wave propagation

Coherent response to a point source irradiating a rough plane

R. J. Lucas and V. Twersky

J. Acoust. Soc. Am. Volume 76, Issue 6, pp. 1847-1863 (1984); (17 pages) | Cited 7 times

Full Text: | Download PDF

Show Abstract
We consider a point source above a rough surface, and write the coherent response as the Sommerfeld–Weyl–Noether integral in terms of the coherent plane‐wave reflection coefficient R for correlated distributions of bosses on rigid or free planes. The uniform asymptotic development of the integral (a generalization of the original Sommerfeld approximation based on the error function complement) is applied to near‐grazing for a rigid base, and graphical results and simple analytical approximations are presented to exhibit the essentials for data inversion programs. The coefficient R and the associated angle‐dependent impedance (determined by the ensemble‐averaged multiple scattering amplitude for one fixed boss) are specified by the single scattered amplitude and the statistical‐mechanics pair distribution function. Low‐frequency illustrations for rigid bosses delineate multipole‐coupling and packing effects on propagation and on attenuation arising from incoherent scattering, as functions of the packing fraction and of the shapes of the bosses and their exclusion regions.
Show PACS
43.20.Fn Scattering of acoustic waves

Classifying particles by acoustical levitation

J. Acoust. Soc. Am. Volume 76, Issue 6, pp. 1864-1864 (1984); (1 page)

Full Text: | Download PDF

Abstract Unavailable
Show PACS
43.35.Ty Other physical effects of sound

Producing metallic glasses with acoustical levitation

J. Acoust. Soc. Am. Volume 76, Issue 6, pp. 1864-1865 (1984); (2 pages)

Full Text: | Download PDF

Abstract Unavailable
Show PACS
43.35.Ty Other physical effects of sound

Studies in evoked potential audiometry

David R. Stapells

J. Acoust. Soc. Am. Volume 76, Issue 6, pp. 1865-1865 (1984); (1 page)

Full Text: | Download PDF

Abstract Unavailable
Show PACS
43.66.Cb Loudness, absolute threshold
43.66.Sr Deafness, audiometry, aging effects
43.64.Ri Evoked responses to sounds

Mie scattering as a technique for the sizing of bubbles

Gary M. Hansen

J. Acoust. Soc. Am. Volume 76, Issue 6, pp. 1865-1865 (1984); (1 page)

Full Text: | Download PDF

Abstract Unavailable
Show PACS
43.35.Ei Acoustic cavitation in liquids
43.30.Nb Noise in water; generation mechanisms and characteristics of the field
43.25.Yw Nonlinear acoustics of bubbly liquids

Acoustic tube shape recovery with specific application to speech analysis

Gregory John Bielby

J. Acoust. Soc. Am. Volume 76, Issue 6, pp. 1865-1865 (1984); (1 page)

Full Text: | Download PDF

Abstract Unavailable
Show PACS
43.72.Ar Speech analysis and analysis techniques; parametric representation of speech

Enhancement of responses to amplitude modulation in the gerbil cochlear nucleus: Single‐unit recordings using an improved surgical approach

Robert D. Frisina

J. Acoust. Soc. Am. Volume 76, Issue 6, pp. 1865-1865 (1984); (1 page)

Full Text: | Download PDF

Abstract Unavailable
Show PACS
43.64.Fy Anatomy of the auditory central nervous system
43.64.Pg Electrophysiology of the auditory nerve
43.64.Qh Electrophysiology of the auditory central nervous system

Nonlinear interaction of two noncollinear sound waves in a waveguide

James A. TenCate

J. Acoust. Soc. Am. Volume 76, Issue 6, pp. 1866-1866 (1984); (1 page)

Full Text: | Download PDF

Abstract Unavailable
Show PACS
43.20.Mv Waveguides, wave propagation in tubes and ducts
43.25.Lj Parametric arrays, interaction of sound with sound, virtual sources

Nichols named Adjunct Research Professor at Monterey

Claude W. Horton, Sr.

J. Acoust. Soc. Am. Volume 76, Issue 6, pp. 1867-1867 (1984); (1 page)

Full Text: | Download PDF

Abstract Unavailable
Show PACS
43.05.Ky Members and membership lists, personal notes, fellows

Keer named ASME Fellow

J. Acoust. Soc. Am. Volume 76, Issue 6, pp. 1867-1867 (1984); (1 page)

Full Text: | Download PDF

Abstract Unavailable
Show PACS
43.05.Ky Members and membership lists, personal notes, fellows

3rd International Modal Analysis Conference

J. Acoust. Soc. Am. Volume 76, Issue 6, pp. 1867-1867 (1984); (1 page)

Full Text: | Download PDF

Abstract Unavailable
Show PACS
43.10.Ce Conferences, lectures, and announcements (not of the Acoustical Society of America)

American Society for Nondestructive Testing: Spring Conference, 11–14 March 1985

J. Acoust. Soc. Am. Volume 76, Issue 6, pp. 1867-1867 (1984); (1 page)

Full Text: | Download PDF

Abstract Unavailable
Show PACS
43.10.Ce Conferences, lectures, and announcements (not of the Acoustical Society of America)
43.35.Zc Use of ultrasonics in nondestructive testing, industrial processes, and industrial products

INTER‐NOISE Seminar Offers Two Courses

J. Acoust. Soc. Am. Volume 76, Issue 6, pp. 1867-1867 (1984); (1 page)

Full Text: | Download PDF

Abstract Unavailable
Show PACS
43.10.Ce Conferences, lectures, and announcements (not of the Acoustical Society of America)
43.10.Sv Education in acoustics, tutorial papers of interest to acoustics educators

Revised subject classification scheme for 1985

J. Acoust. Soc. Am. Volume 76, Issue 6, pp. 1868-1868 (1984); (1 page)

Full Text: | Download PDF

Abstract Unavailable
Show PACS
43.05.-k Acoustical Society of America
43.10.Ce Conferences, lectures, and announcements (not of the Acoustical Society of America)

Mechanical Vibrations for Engineers by Michel Lalanne, Patrick Berthier, and Johan Der Hagopian

Michel Lalanne, Author, Patrick Berthier, Author, Johan Der Hagopian, Author, and Courtney B. Burroughs

J. Acoust. Soc. Am. Volume 76, Issue 6, pp. 1870-1870 (1984); (1 page)

Full Text: | Download PDF

Abstract Unavailable
Show PACS
43.10.Hj Books and book reviews
43.40.-r Structural acoustics and vibration

Introduction to Random Vibrations by N. C. Nigam

N. C. Nigam, Author and William D. Mark

J. Acoust. Soc. Am. Volume 76, Issue 6, pp. 1871-1871 (1984); (1 page)

Full Text: | Download PDF

Abstract Unavailable
Show PACS
43.10.Hj Books and book reviews
43.40.Hb Random vibration

Sonic levitation apparatus (P)

Stanley A. Dunn, Alan R. Pomplun, Elmer G. Paquette, Edwin C. Ethridge, and Jerry L. Johnson

J. Acoust. Soc. Am. Volume 76, Issue 6, pp. 1872-1872 (1984); (1 page)

Full Text: | Download PDF

Abstract Unavailable
Show PACS
43.25.Vt Intense sound sources

Long wavelength acoustic flowmeter (P)

James E. Potzick and Baldwin Robertson

J. Acoust. Soc. Am. Volume 76, Issue 6, pp. 1872-1872 (1984); (1 page)

Full Text: | Download PDF

Abstract Unavailable
Show PACS
43.28.Bj Mechanisms affecting sound propagation in air, sound speed in the air

Oceanographic measurement system (P)

John C. Beckerle

J. Acoust. Soc. Am. Volume 76, Issue 6, pp. 1873-1873 (1984); (1 page)

Full Text: | Download PDF

Abstract Unavailable
Show PACS
43.30.Bp Normal mode propagation of sound in water
Page 2 of 5 Pages Previous Page Next Page | Jump to Page
Close

Home Publications Meetings Contact ASA Site Map Back to Top

Copyright © Acoustical Society of America

close