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Journal of the Acoustical Society of America

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Nov 1971

Volume 50, Issue 5B, pp. 1281-1396


Fifty Years of Ferroelectricity

Warren P. Mason

J. Acoust. Soc. Am. Volume 50, Issue 5B, pp. 1281-1298 (1971); (18 pages)

Online Publication Date: 11 Aug 2005

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Developments in the field of ferroelectricity are traced from the discovery of the ferroelectric effect by Joseph Valasek in 1921 to its use in a variety of modern applications. Its appearance and utilization in different substances is discussed.

A Recursive Procedure for Computing the Nonlinear Spectral Interactions of Progressive Finite‐Amplitude Waves in Nondispersive Fluids

Francis Hugh Fenlon

J. Acoust. Soc. Am. Volume 50, Issue 5B, pp. 1299-1312 (1971); (14 pages) | Cited 4 times

Online Publication Date: 11 Aug 2005

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A method for computing nonlinear interactions between the spectral lines of progressive finite‐amplitude waves in homogeneous media is developed via Burgers' equation. By means of Fourier analysis, this equation is reduced to a coupled set of ordinary nonlinear differential equations, which are then solved recursively using Airy's algorithm. The solution thus obtained has the form of a vector which initially contains the spectral amplitudes of the source waveform and is subsequently enriched by nonlinearly generated spectral components as the signal propagates through the medium. The utility of the method consists in the ease with which it can be implemented on a digital computer and its applicability to a wide variety of source waveforms.

Shock Beaming Capabilities of Hydrodynamic Conical Shock Tubes

William S. Filler

J. Acoust. Soc. Am. Volume 50, Issue 5B, pp. 1313-1320 (1971); (8 pages) | Cited 1 time

Online Publication Date: 11 Aug 2005

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An experimental study was made of the shock wave projected into free water from the end of a hydrodynamic conical shock tube driven by a high explosive. Pressure‐time measurements were made with small piezoelectric and piezoresistive gauges arrayed about two different shock tube configurations. For one tube, designed on a very small scale, results showed that a remnant of the sector shock front propagated undisturbed over the length of the water tank (20 cone lengths). This was demonstrated by the fact that attenuation with distance along the extended cone axis closely approximated the accepted relationship P ∝ R−1.13 for explosion shock waves in free water. On‐axis data for the other tube whose shock wave energy was three orders of magnitude greater than the first, showed very rapid attenuation beyond the cone mouth. Both cone results are consistent with existing theory that defines the undisturbed shock front region in terms of cone parameters—length, angle, and amount of explosive—that affect shock energy and geometry. Results for the first cone on attenuation of pressure with angle to the axis also were consistent with the predicted angular extent of the undisturbed front region. At 30°, attenuation was about 75%.

A Decade of Experience with Velocimeters

Kenneth V. Mackenzie

J. Acoust. Soc. Am. Volume 50, Issue 5B, pp. 1321-1333 (1971); (13 pages) | Cited 1 time

Online Publication Date: 11 Aug 2005

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Over a decade of experience with velocimeters aboard deep submergence vehicles has demonstrated that accuracies of 0.1 m/sec or better can be obtained with proper procedures. Calibrations and distilled water equations are discussed, along with the new International Temperature Scale adopted in 1968. Calibration drift is described for three types of velocimeters to underscore that accuracy requires frequent calibrations as well as intercomparisons between several instruments during. deep dives. Pressure corrections are computed. Errors due to thermal lags of earlier velocimeters were observed while transmitting thermoclines. Laboratory measurements with a velocimeter in 50 gal of natural seawater of 27.405‰ salinity gave good results, closer to those of V. A. Del Grosso [J. Acoust. Soc. Amer. 47, 947 (1970)], than to W. D. Wilson [J. Acoust. Soc. Amer. 32, 1357 (L) (1960)].

Transmission of Acoustic Waves through Submerged Orthotropic Spherical Shells

Mohammed Naghieh and Sabih I. Hayek

J. Acoust. Soc. Am. Volume 50, Issue 5B, pp. 1334-1342 (1971); (9 pages) | Cited 1 time

Online Publication Date: 11 Aug 2005

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The problem of transmission of acoustic waves through submerged orthotropic spherical shells was considered. The sound radiation in an infinite acoustic fluid is induced by a rigid spherical transducer, concentric within an orthotropic spherical shell having an axisymmetric surface‐velocity distribution. The space between the spherical transducer and the orthotropic spherical shell is full of the same acoustic fluid as that outside of the shell. The equations of motion for orthotropic shells, as well as for the fluid inside and outside, were derived. These equations are then solved by satisfying the continuity conditions on all solid‐fluid interfaces. Four representative transducer surface‐velocity distributions were considered. The solution for the farfield acoustic pressure was obtained for an orthotropic and for an isotropic shell.

Acoustic Radiation Impedance of Caps and Rings on Prolate Spheroids

A. L. Van Buren

J. Acoust. Soc. Am. Volume 50, Issue 5B, pp. 1343-1356 (1971); (14 pages) | Cited 2 times

Online Publication Date: 11 Aug 2005

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The self‐acoustic radiation impedance of cap‐shaped and ring‐shaped pistons conformal to a rigid prolate spheroidal baffle and vibrating with uniform normal velocity is calculated using prolate spheroidal wave functions. The necessary spheroidal functions are obtained using recently developed FORTRAN computer programs. Plots of the normalized radiation resistance and the normalized radiation reactance as functions of the acoustic size parameter h are presented for several different baffle shapes and relative piston sizes. The effect of the baffle size and curvature on the radiation impedance is shown to be small.

Kinematics of Wide‐Band Field Sensing by Extended Sensors in Motion

Ewald Eichler

J. Acoust. Soc. Am. Volume 50, Issue 5B, pp. 1357-1371 (1971); (15 pages)

Online Publication Date: 11 Aug 2005

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This analytical study concerns the sensing of wide‐band pressure fields by moving receivers or sensors. Treated are linear kinematical aspects for ideal sensors that travel at constant subsonic or supersonic velocities. The fields are described in wave‐harmonic (wavenumber‐frequency) space. The sensed signal or noise components are related at their sensed frequencies and on a spectral basis. It is shown that the point sensor is no longer uniform or nondirective once it moves. Its directional pattern, and that of spatially extended sensors, too, depends upon the Mach number of sensor motion, upon the sensed frequency, and even upon the choice of a reference spectrum for the fields in the resting fluid. A certain compensation for the effects of motion is possible in directive sensors by adjustment of parameters. This compensation, however, is partial and permits only the preservation of some crucial feature. The adjustment is explained in terms of a “matched Mach number” for back‐nulled gradient and endfire‐line sensors. The definition of gain is amended, and the concept of the equivalent signals of sensed field components is recommended as a suitable measure of a sensing situation. Equivalent spectra of noise incident from the rear and of isotropic noise are presented for velocity‐matched back‐hulled gradient and endfire‐line sensors; depending upon frequency and reference spectrum, they differ from their rest values.

Sampling Statistics for a Cylindrical Mode

Richard Waterhouse and Chi‐Shing Chien

J. Acoust. Soc. Am. Volume 50, Issue 5B, pp. 1372-1378 (1971); (7 pages)

Online Publication Date: 11 Aug 2005

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The distribution functions are considered for the random sampling in space of a three‐dimensional acoustic mode. These functions are of interest when it is desired to estimate either the total acoustic energy present in the space, from a finite number of sample values, or the driving‐point impedance at an arbitrarily chosen point. Expressions are obtained for the probability density function (pdf) and cumulative function for a single mode excited in an ideal elastic fluid in a right circular cylindrical enclosure. Two kinds of axisymmetric mode are considered, those corresponding to the first zeros of the zero‐ and first‐order Bessel functions. The distribution functions obtained are compared with those for modes in a rectangular enclosure [R. V. Waterhouse, J. Acoust. Soc. Amer. 47, 961–967 (1970)], and exhibit some novel and interesting features. For the cylindrical modes, the pdf's differ for each order of one type of mode, and in general have discontinuities, the number of which increases with the mode number. In both these respects the cylindrical modes differ from the rectangular modes.
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A Passive Analyzer for Ultrasonic Shear Waves

Thomas M. Proctor, Jr.

J. Acoust. Soc. Am. Volume 50, Issue 5B, pp. 1379-1381 (1971); (3 pages) | Cited 1 time

Online Publication Date: 11 Aug 2005

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A device has been developed which allows the determination of the direction of shear particle motion generated by a single transducer. The normal ways of determining shear motion are to use another crystal of known polarization or to know the crystallographic geometry. This device analyzes the shear motion by use of reflection modes in a multiwaveguide assembly. The shear motion can be related to the geometry of this waveguide assembly.

Comments on “Beam Behavior within the Nearfield of a Vibrating Piston” [J . Zemanek, J. Acoust. Soc. Amer. 49, 181–188 (1971)]

Patricio A. Laura

J. Acoust. Soc. Am. Volume 50, Issue 5B, pp. 1381-1381 (1971); (1 page)

Online Publication Date: 11 Aug 2005

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The present letter discusses additional technical literature dealing with calculations of nearfield pressure induced by vibrating acoustic transducers.

An Accelerating Force on a String

W. J. Stronge

J. Acoust. Soc. Am. Volume 50, Issue 5B, pp. 1382-1383 (1971); (2 pages)

Online Publication Date: 11 Aug 2005

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An infinitely long, perfectly flexible string is subjected to a transverse force that moves with arbitrary speed. The effect of the force accelerating through a resonant speed is determined. This invariably results in large deformations if the force is concentrated. With a distributed force, the deformations can remain small if the force accelerates through the resonant speed rapidly.

An Asymptotic Analysis of the End Mode in a Circular Disk

J. Tasi

J. Acoust. Soc. Am. Volume 50, Issue 5B, pp. 1384-1386 (1971); (3 pages)

Online Publication Date: 11 Aug 2005

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An asymptotic solution is obtained for the end mode in a circular disk, using second‐order plate theory. Variation of end displacement with radius is indicated, and estimates of midpoints of the plateaus in the frequency spectrum are found. The results of a three‐dimensional elasticity solution are given for frequency and modal displacement and compare reasonably well with available experimental results.

Independent Multiple Oscillations of a Single Quartz Wafer

F. J. Van Empel, C. H. Massen, H. J. J. M. Arts, and J. A. Poulis

J. Acoust. Soc. Am. Volume 50, Issue 5B, pp. 1386-1387 (1971); (2 pages) | Cited 1 time

Online Publication Date: 11 Aug 2005

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Experiments are described which demonstrate that the frequency of different electronic oscillators can be independently controlled by electrode systems evaporated on a single quartz wafer. This arrangement can be used in several fields of applications, where the use of separate quartz wavers for the oscillators would imply errors due to temperature and other environmental differences.

Minimum Effectiveness of Isolation Mounts at High Frequencies

W. M. Wang

J. Acoust. Soc. Am. Volume 50, Issue 5B, pp. 1388-1389 (1971); (2 pages)

Online Publication Date: 11 Aug 2005

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The effectiveness of one‐degree‐of‐freedom vibration isolation mounts is examined. It is shown that, at high frequencies where standing‐wave resonances occur in mounts and structural resonances occur in the machine and the foundation, there exists a functional lower bound of the mount effectiveness, regardless of machine and foundation impedance variations. This functional lower bound is obtained and its significance is discussed.

Investigation of Double‐Diffusive Convection Using an Ultrasonic Pulse‐Echo Technique

M. G. Kim, R. B. Lambert, and S. V. Letcher

J. Acoust. Soc. Am. Volume 50, Issue 5B, pp. 1389-1392 (1971); (4 pages)

Online Publication Date: 11 Aug 2005

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Propagation of ultrasound is investigated in an aqueous solution stratified by two solutes which diffuse at different rates. Both the finger interface and the diffusive interface are considered. Following correction for background absorption, edge effects, and refraction, attenuation of the order of 1.4 dB/cm is observed in the finger interface, while no attenuation is detected in the diffusive interface. The attenuation increases with frequency from 0.8 to 25 MHz. For higher frequencies, up to 42 MHz, the attenuation is constant. The loss is attributed to an as yet unspecified scattering mechanism.

Sound Pressure in Water from Source in Air

Robert W. Young

J. Acoust. Soc. Am. Volume 50, Issue 5B, pp. 1392-1393 (1971); (2 pages)

Online Publication Date: 11 Aug 2005

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Sound pressure in the water under a point source overhead in air is shown by theory and experiment to propagate as from a virtual source situated (c1/c2) times the actual source height above the water and emitting unit‐distance sound pressure that is (2c1/c2) times the actual unit‐distance sound pressure, where c1 and c2 are the speeds of sound in air and water, respectively.

Reflections of Weak Shock Waves from Acoustic Materials

M. Cloutier, F. Devereux, P. Doyon, A. Fitchett, D. Heckman, L. Moir, and L. Tardif

J. Acoust. Soc. Am. Volume 50, Issue 5B, pp. 1393-1396 (1971); (4 pages)

Online Publication Date: 11 Aug 2005

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A number of materials having good acoustic absorption properties have been tested in order to determine their relative effectiveness in attenuating weak high‐frequency shock waves propagating atmospheric air. Weak shock waves with an N‐wave configuration of about 110‐μsec duration were generated by rifle bullets flying 2400 ft/sec over samples of acoustic material supported on a metal plate, and the details of the reflection of these waves at the surface of the various materials were monitored by using shadowgraph‐schlieren photographic techniques and pressure transducers. The urethane materials available gave a high amount of surface reflection compared to fiberglass materials of similar density. The least surface reflection was obtained with very low density (less than 1.0 lb/ft2 fiberglass).
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