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Journal of the Acoustical Society of America
obtained and compared with the experimental ones. It is shown that theory and experiment are in good agreement with each other. Production and demonstration of helical surface waves over cylindrical bodies by non-contacting electrodynamic transducers Herbertz, von J. 27 (September 1972) 113 Surface waves on cylindrical bodies may propagate themselves in helical modes differing in periodicity number and sense of rotation. Non-contacting electro dynamic transducers can be adjusted as a transmitter and a receiver selective in a single mode. Suitably continuous sound transmission techniques will be described with respect to a material testing method involving mode-changing at faults. With the help of this method the transmission of helical modes on non-magnetic metal tubes and pipes is experimentally demonstrated. A contribution to the technique of contactfree stimulation of waves in plates Licht, von H.
27 (September 1972) 131 A contact-free plate-wave transmitter is described which generates eddy currents at the surface of steel plates.
On the influence of cavitation volume on the cavitation mechanism
Jungclaus, von H. J. 27 (September 1972) 145 Experimental conditions are described and a method discussed permitting the variation of cavitation volume without markedly changing the surrounding wall faces. In this way a distinction can be gained between the ‘activity’ of ‘volume nuclei’ and ‘wall nuclei’ and information derived on the mode of nucleus building. Representation
of the freezing-in phenomenon
of sound in air at 2O’C. The results agree within 3% of previous work in the frequency range of 100 Hz-l MHz for all humidities. Below 100 Hz accuracy cannot be judged because of lack of knowledge about the vibration-vibrationfnergy transfer between COz and Oz.
Acoustic wave interaction with a coherent light beam Gruber, S., Marhic, M. 52 (September 1972) 826
A theoretical treatment of the effect of pressure fluctuations on the phase of an electromagnetic wave propagating through them is developed. The pressure variations may be either acoustic or turbulent in nature. An experiment in which acoustic noise excitation of a weakly resonant system is measured by laser interferometry is also described.
Ultrasonic relaxation in aqueous acetic acid solution Jackopin, L. G., Yeager, E. 52 (September 1972) 831
Ultrasonic absorption measurements have been made in acqueous acetic solutions at 15-85 MHz using pulse-echo and pulse send-receive techniques. A weighted non-linear regression method has been developed for the computation of the relaxation parameters. A single relaxation has been found with a relaxation frequency at 13.2 MHz in O.lM acetic acid and 66.1 MHz in l.OM acetic acid at 25’C. These values and the maximum excess relaxational absorption per wavelength are in good agreement with the values calculated from equilibrium and kinetic parameters for the ionization of acetic acid asdetermined by nonacoustical techniques. The rate constants and reaction volume change of the ionizationassociation process, calculated from the ultrasonic absorption measuremenrs in acetic acid, are k&ssoc ; 7_..,8 x 10” s-‘, k~SS~ = 4.4 x 1010 r s Avdissoc
= 11.2 cm
mole-f ytd&c
of standing ultrasonic waves in concentra-
.
tion grad&s by means of the optical Philpot-Svensson Method
Scattering of sound by air bubbles in water
Haun, von L., Schaaffs, W. 27 (September 1972) 166
Mole, L. A., Hunter, J. L., Davenport, J. M. 52 (September 1972) 837
The optical Philpot-Svensson method is used to image a standing ultrasonic wave. The characteristic of representation is that the method yields directly, in rectangular co-ordinates, the graph of the gradient of the index of refraction of the standing wave. From this graph the variations in density, the sound pressure and other characteristics of the sound field can be found.
The scattering strength of air bubbles in water has been determined experimentally at frequencies of 1 and 5 MHz. The bubble size and sound frequencies represent the short wavelength limit, where ku > 1. By scanning the sound fields with a pzt transducer of 1 mm radius, angular distribution have been obtained out to an angle of 35 degrees with and without the scatterers present. The results agree well with recent scattering measurements in suspensions and also with scattering
JOURNAL OF THE ACOUSTICALtheo”‘. SOCIETY OF AMERICA Atmospheric
absorption
Absolute accuracy of the pulse-echo overlap method and the pulse-superposition method
of sound:
analyti‘cal expressions Bass. H. E.. Bauer. H. J.. Evans, L. B. 52 (September 1972) 821
for ultrasonic velocity Papadakis, E. P. 52.(September 1972) 843
A set of analytical expressions has been developed which will predict the absorption
It is shown that the errors in the absolute values of the measured delay times (after
ULTRASONICS.
JANUARY
1973
correction for diffraction phase and bond thickness) in the pulse-echo overlap and the pulsesuperposition methods can be less than 0.0157 and 0.0277, respectively, where r is the period of the fundamental radio frequency of the transducer used. If broad-band pulses are used with the pulseecho overlap method, then the error is larger but still less than 0.10~ at the centre frequency. Translated Hto fractional errors in the single round-trip delay time, the errors may be as small as a few parts per million.
Ultrasonic diffraction loss and phase change for broad-band pulses Papadakis, E. P. 52 (September 1972) 847 The effective diffraction loss and phase change in the field of broad-band transducers is computed in terms of the normalized distance S, = zhc/a2 at the centre frequency of the pulse. Diffraction corrections for attenuation and velocity are explained, and their limitations stated for broad-band pulses. It is shown that the corrections are functions of bandwidth as well as of Sc. Ultrasonic attenuation and velocity in hot specimens by the momentary contact method with pressure coupling, and some results on steel to 1 2OO’C Papadakis, E. P., Lynnworth, L. C., Fowler, K. A., Carnevale, E. H. 52 (September 1972) 850 The momentary contact pulse-echo method with pressure coupling has been extended to the measurement of ultrasonic attenuation in hot specimens. In the present method the specimen is contacted momentarily by one end of a cool buffer rod about three times as long as the specimen. A piezoelectric transducer on the other end of the buffer rod transmits an ultrasonic signal and receives echoes from the buffer/specimen interface and from the free end of the specimen. Three echoes are required to define both the attenuation coefficient in the specimen and the reflection coefficient at the buffer/ specimen interface. Results in steel’show that the solution and precipitation of carbides affect the velocity drastically, while the attenuation is affected by at least one of the following: (1) magnetism (2) recrystallization, or (3) carbon solubility, and also by grain growth at elevated temperatures. Acoustic field of circular plane piston in limits of short wavelength or large radius Rogers, P. H., Williams Jr, A. 0.
52 (September 1972) 865 The acoustic beam of a circular plane piston (radius n) is analysed as it approaches either the short-wavelength limit (SWL) or the large-radius limit (LRL). Using a new expression for the beam, it is shown that, with no absorption, the SWL would be a cylindrically collimated beam, with radius u, of plane waves. If absorptive effects are minor, the chief deviations during approach to the SWL occur in two decreasing volumes, a horn-shaped paraxial region and a cylindrical shell of mean radius n.
47
27 (September 1972) 131 A contact-free plate-wave transmitter is described which generates eddy currents at the surface of steel plates.
On the influence of cavitation volume on the cavitation mechanism
Jungclaus, von H. J. 27 (September 1972) 145 Experimental conditions are described and a method discussed permitting the variation of cavitation volume without markedly changing the surrounding wall faces. In this way a distinction can be gained between the ‘activity’ of ‘volume nuclei’ and ‘wall nuclei’ and information derived on the mode of nucleus building. Representation
of the freezing-in phenomenon
of sound in air at 2O’C. The results agree within 3% of previous work in the frequency range of 100 Hz-l MHz for all humidities. Below 100 Hz accuracy cannot be judged because of lack of knowledge about the vibration-vibrationfnergy transfer between COz and Oz.
Acoustic wave interaction with a coherent light beam Gruber, S., Marhic, M. 52 (September 1972) 826
A theoretical treatment of the effect of pressure fluctuations on the phase of an electromagnetic wave propagating through them is developed. The pressure variations may be either acoustic or turbulent in nature. An experiment in which acoustic noise excitation of a weakly resonant system is measured by laser interferometry is also described.
Ultrasonic relaxation in aqueous acetic acid solution Jackopin, L. G., Yeager, E. 52 (September 1972) 831
Ultrasonic absorption measurements have been made in acqueous acetic solutions at 15-85 MHz using pulse-echo and pulse send-receive techniques. A weighted non-linear regression method has been developed for the computation of the relaxation parameters. A single relaxation has been found with a relaxation frequency at 13.2 MHz in O.lM acetic acid and 66.1 MHz in l.OM acetic acid at 25’C. These values and the maximum excess relaxational absorption per wavelength are in good agreement with the values calculated from equilibrium and kinetic parameters for the ionization of acetic acid asdetermined by nonacoustical techniques. The rate constants and reaction volume change of the ionizationassociation process, calculated from the ultrasonic absorption measuremenrs in acetic acid, are k&ssoc ; 7_..,8 x 10” s-‘, k~SS~ = 4.4 x 1010 r s Avdissoc
= 11.2 cm
mole-f ytd&c
of standing ultrasonic waves in concentra-
.
tion grad&s by means of the optical Philpot-Svensson Method
Scattering of sound by air bubbles in water
Haun, von L., Schaaffs, W. 27 (September 1972) 166
Mole, L. A., Hunter, J. L., Davenport, J. M. 52 (September 1972) 837
The optical Philpot-Svensson method is used to image a standing ultrasonic wave. The characteristic of representation is that the method yields directly, in rectangular co-ordinates, the graph of the gradient of the index of refraction of the standing wave. From this graph the variations in density, the sound pressure and other characteristics of the sound field can be found.
The scattering strength of air bubbles in water has been determined experimentally at frequencies of 1 and 5 MHz. The bubble size and sound frequencies represent the short wavelength limit, where ku > 1. By scanning the sound fields with a pzt transducer of 1 mm radius, angular distribution have been obtained out to an angle of 35 degrees with and without the scatterers present. The results agree well with recent scattering measurements in suspensions and also with scattering
JOURNAL OF THE ACOUSTICALtheo”‘. SOCIETY OF AMERICA Atmospheric
absorption
Absolute accuracy of the pulse-echo overlap method and the pulse-superposition method
of sound:
analyti‘cal expressions Bass. H. E.. Bauer. H. J.. Evans, L. B. 52 (September 1972) 821
for ultrasonic velocity Papadakis, E. P. 52.(September 1972) 843
A set of analytical expressions has been developed which will predict the absorption
It is shown that the errors in the absolute values of the measured delay times (after
ULTRASONICS.
JANUARY
1973
correction for diffraction phase and bond thickness) in the pulse-echo overlap and the pulsesuperposition methods can be less than 0.0157 and 0.0277, respectively, where r is the period of the fundamental radio frequency of the transducer used. If broad-band pulses are used with the pulseecho overlap method, then the error is larger but still less than 0.10~ at the centre frequency. Translated Hto fractional errors in the single round-trip delay time, the errors may be as small as a few parts per million.
Ultrasonic diffraction loss and phase change for broad-band pulses Papadakis, E. P. 52 (September 1972) 847 The effective diffraction loss and phase change in the field of broad-band transducers is computed in terms of the normalized distance S, = zhc/a2 at the centre frequency of the pulse. Diffraction corrections for attenuation and velocity are explained, and their limitations stated for broad-band pulses. It is shown that the corrections are functions of bandwidth as well as of Sc. Ultrasonic attenuation and velocity in hot specimens by the momentary contact method with pressure coupling, and some results on steel to 1 2OO’C Papadakis, E. P., Lynnworth, L. C., Fowler, K. A., Carnevale, E. H. 52 (September 1972) 850 The momentary contact pulse-echo method with pressure coupling has been extended to the measurement of ultrasonic attenuation in hot specimens. In the present method the specimen is contacted momentarily by one end of a cool buffer rod about three times as long as the specimen. A piezoelectric transducer on the other end of the buffer rod transmits an ultrasonic signal and receives echoes from the buffer/specimen interface and from the free end of the specimen. Three echoes are required to define both the attenuation coefficient in the specimen and the reflection coefficient at the buffer/ specimen interface. Results in steel’show that the solution and precipitation of carbides affect the velocity drastically, while the attenuation is affected by at least one of the following: (1) magnetism (2) recrystallization, or (3) carbon solubility, and also by grain growth at elevated temperatures. Acoustic field of circular plane piston in limits of short wavelength or large radius Rogers, P. H., Williams Jr, A. 0.
52 (September 1972) 865 The acoustic beam of a circular plane piston (radius n) is analysed as it approaches either the short-wavelength limit (SWL) or the large-radius limit (LRL). Using a new expression for the beam, it is shown that, with no absorption, the SWL would be a cylindrically collimated beam, with radius u, of plane waves. If absorptive effects are minor, the chief deviations during approach to the SWL occur in two decreasing volumes, a horn-shaped paraxial region and a cylindrical shell of mean radius n.
47