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Attenuation of low-frequency sound waves in sediments
ABSTRACTS The abstracts survey, a regular feature of each issue of U L T R A S O N ICS, contains recent patent information and reports of new literature in the field. Copies of original articles are best obtained by writing to the journal in which they appeared. The addresses of these journals can be found in reference books such as 'World List of Scientific and Technical Publications', 'Willings Press Guide', 'Newspaper Press Directory', or (for American journals) 'Ayers'. J O U R N A L OF THE A C O U S T I C A L SOCIETY OF A M E R I C A
On the d y n a m i c behaviour of a cable system in a recovery operation Laura, P. A., Goeller, J. E. Vol 49, No 3, Part 1 (March 1971) pp 615 621 A new class of adaptive array processors (?hang, J. H., Tuteur, F. B. Vol 49, No 3, Part 1 (March 1971 pp 6 3 9 649 Development of an underwater acoustics laboratory course Weinberg, N. L., G r a n t h a m , W. G. Vo149, No 3, Part 2 (March 1971) pp 6 9 7 705 Ultrasonic m e a s u r e m e n t in liquid alkali metals Kim, M. G., Kemp, K. A., Letcher, S. V. Vol 49, No 3, Part 2 (March 1971) pp 706 712 Ultrasonic adsorption and velocity measurem e n t s have been made in high-purity liquid sodium, potassium, rubidium, and caesium at temperatures from their melting points to 250°C. Corresponding classical absorption values have also been c o m p u t e d over these ranges of temperature. It has been f o u n d that the measured absorption values exceed the classical values by 3% 30%. These excess absorptions are attributed to structural relaxation. The ratio o f bulk viscosity to shear viscosity was found to be approximately 2.3 in sodium and potassium, 3.4 in rubidium, and 4 in caesium. Sound velocities arc presented as linear functions of temperature. Both observed and classical absorptions are given as quadratic functions of temperature. A water immersion technique for measuring attenuation and phase velocity of longitudinal waves in plastics McSkimin, H. J., Andreateh, P. Jr. Vol 49, No 3, Part 2 (March 1971) pp 7 1 3 722 The-complex transmission coefficient for a plastic specimen immersed in water (or other suitable liquid) is determined through use of a phase meter and a calibrated attenuator. Heterodyning the received rf pulses
ULTRASONICS
. OCTOBER
1971
directly to video signals with a 10 HzSoeat frequency makes possible (1) the use of a commercial low-frequency phase meter, and (2),an increase in signal-to-noise ratio of approximately 20 dB (H. J. McSkimin and T. B. Bateman, J. Acoust. Soc. Amer. 45, 852 858 (1969)). By way of illustration, m e a s u r e m e n t s for attenuation and phase velocity are listed for a n u m b e r of specimens, including Plexiglas (acrylate and methacrylate resin), Epon adhesive, e p o x y foam, and several composite structures. The frequency and temperature ranges covered were 0.4 1.1 MHz and 20°C 60°C respectively.
Elastic constants of D 2 0 ice and variation of intermolecular forces on deuteration Mitzdorf, U., Helmreich, D. Vol 49, No 3, Part 2 (March 1971) pp 723 728 The elastic constants of D 2 0 ice have been measured between 0 ° and 140°C. From these data and the elastic constants of H 2 0 ice, the molecular force constants K for change of bond length and G for change of 0 . . . 0 . . . 0 angle have been calculated. K and G show a similar temperature dependence to the elastic constants; their absolute values increase on deuteration. For comparison, values of K and G calculated from infrared data are given.
Ultrasonic waveguide effects in inhomogeneous rods with radial s y m m e t r y Papadakis, E. P. Vol 49, No 3, Part 2 (March 1971) pp 7 2 9 731 When sound waves are generated in a h o m o geneous rod m a n y wavelengths in diameter by a transducer of smaller diameter affixed coaxially to it's end, the pressure received by the same transducer in a pulse-echo mode or by a similar transducer on the other end of the rod is not a m o n o t o n i c function of the length of the rod. There are strong fluctuations in sound level with length. The fluctuations are caused by waveguide effects. These effects have been made inoperative in the past by techniques such as cutting screw threads on the surface of the rod. In this experiment, the material of the rod itself was made i n h o m o g e n e o u s in a radially symmetric m a n n e r by heat treatment. It was f o u n d that the waveguide fluctuations were extinguished and the wave died o u t exponentially in the i n h o m o g e n e o u s rods. Much background noise, however, was generated through the spatial diffusion of the wave.
Attenuation of low-frequency sound waves in sediments Anderson, R. S., Blackman, A. Vol 49, No 3, Part 2 (March 1971) pp 786 791 Acoustical detection of single cavitation events in the focused field in water at I MHz Coakley, W. T. Vol 49, No 3, Part 2 (March 1971) pp 792 801 Acoustic intensities up to 1400 W/cm 2 have been generated at the focus of a ceramic bowl. The rf voltage applied to the transducer has been rectified and filtered and the signals produced from cavitation events have been examined. A directional hydrophone simultaneously monitoring the focal point aided interpretation of the signals detected by the driven bowl. Low-amplitude low-frequency signals appeared on the driven bowl synchronously with the onset of first subharmonic emission in the water at an intensity of 13 W/cm 2. Thc subharmonic increased rapidly with increasing sound intensity and then levelled off. Just before this occurred, the scattering properties of the focal region increased markedly and a cyclic signal, interpreted as indicating the production of clouds of microbubbles when surface oscillations set in on the cavitation bubbles, were detected on the filter circuit. Strongly radiating single cavitation cvcnts lasting for the order of milliseconds were also detected. The amplitude, duration, and rate of occurrence of these events wcrc all one to two orders of magnitude greater in tap than in degassed water. Observation of wind-wave-generated Doppler shifts in surface reverberation lgarashi, Y., Stern, R. Vol 49, No 3, Part 2 (March 1971) pp 802 809 Low-frequency acoustic attenuation in the South Pacific ocean Kibblewhite, A. C., Denham, R. N. Vol 49, No 3, Part 2 (March 1971) pp 8 1 0 815 Dorsal-aspect target strength of an individual fish Love, R. H. Vol 49, No 3, Part 2 (March 1971) pp 816 823 Focusing and refraction of harmonic sound and transient pulses in stratified media Sachs, D. A., Silbiger, A. Vol 49, No 3, Part 2 (March 1971) pp 824 840
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On the d y n a m i c behaviour of a cable system in a recovery operation Laura, P. A., Goeller, J. E. Vol 49, No 3, Part 1 (March 1971) pp 615 621 A new class of adaptive array processors (?hang, J. H., Tuteur, F. B. Vol 49, No 3, Part 1 (March 1971 pp 6 3 9 649 Development of an underwater acoustics laboratory course Weinberg, N. L., G r a n t h a m , W. G. Vo149, No 3, Part 2 (March 1971) pp 6 9 7 705 Ultrasonic m e a s u r e m e n t in liquid alkali metals Kim, M. G., Kemp, K. A., Letcher, S. V. Vol 49, No 3, Part 2 (March 1971) pp 706 712 Ultrasonic adsorption and velocity measurem e n t s have been made in high-purity liquid sodium, potassium, rubidium, and caesium at temperatures from their melting points to 250°C. Corresponding classical absorption values have also been c o m p u t e d over these ranges of temperature. It has been f o u n d that the measured absorption values exceed the classical values by 3% 30%. These excess absorptions are attributed to structural relaxation. The ratio o f bulk viscosity to shear viscosity was found to be approximately 2.3 in sodium and potassium, 3.4 in rubidium, and 4 in caesium. Sound velocities arc presented as linear functions of temperature. Both observed and classical absorptions are given as quadratic functions of temperature. A water immersion technique for measuring attenuation and phase velocity of longitudinal waves in plastics McSkimin, H. J., Andreateh, P. Jr. Vol 49, No 3, Part 2 (March 1971) pp 7 1 3 722 The-complex transmission coefficient for a plastic specimen immersed in water (or other suitable liquid) is determined through use of a phase meter and a calibrated attenuator. Heterodyning the received rf pulses
ULTRASONICS
. OCTOBER
1971
directly to video signals with a 10 HzSoeat frequency makes possible (1) the use of a commercial low-frequency phase meter, and (2),an increase in signal-to-noise ratio of approximately 20 dB (H. J. McSkimin and T. B. Bateman, J. Acoust. Soc. Amer. 45, 852 858 (1969)). By way of illustration, m e a s u r e m e n t s for attenuation and phase velocity are listed for a n u m b e r of specimens, including Plexiglas (acrylate and methacrylate resin), Epon adhesive, e p o x y foam, and several composite structures. The frequency and temperature ranges covered were 0.4 1.1 MHz and 20°C 60°C respectively.
Elastic constants of D 2 0 ice and variation of intermolecular forces on deuteration Mitzdorf, U., Helmreich, D. Vol 49, No 3, Part 2 (March 1971) pp 723 728 The elastic constants of D 2 0 ice have been measured between 0 ° and 140°C. From these data and the elastic constants of H 2 0 ice, the molecular force constants K for change of bond length and G for change of 0 . . . 0 . . . 0 angle have been calculated. K and G show a similar temperature dependence to the elastic constants; their absolute values increase on deuteration. For comparison, values of K and G calculated from infrared data are given.
Ultrasonic waveguide effects in inhomogeneous rods with radial s y m m e t r y Papadakis, E. P. Vol 49, No 3, Part 2 (March 1971) pp 7 2 9 731 When sound waves are generated in a h o m o geneous rod m a n y wavelengths in diameter by a transducer of smaller diameter affixed coaxially to it's end, the pressure received by the same transducer in a pulse-echo mode or by a similar transducer on the other end of the rod is not a m o n o t o n i c function of the length of the rod. There are strong fluctuations in sound level with length. The fluctuations are caused by waveguide effects. These effects have been made inoperative in the past by techniques such as cutting screw threads on the surface of the rod. In this experiment, the material of the rod itself was made i n h o m o g e n e o u s in a radially symmetric m a n n e r by heat treatment. It was f o u n d that the waveguide fluctuations were extinguished and the wave died o u t exponentially in the i n h o m o g e n e o u s rods. Much background noise, however, was generated through the spatial diffusion of the wave.
Attenuation of low-frequency sound waves in sediments Anderson, R. S., Blackman, A. Vol 49, No 3, Part 2 (March 1971) pp 786 791 Acoustical detection of single cavitation events in the focused field in water at I MHz Coakley, W. T. Vol 49, No 3, Part 2 (March 1971) pp 792 801 Acoustic intensities up to 1400 W/cm 2 have been generated at the focus of a ceramic bowl. The rf voltage applied to the transducer has been rectified and filtered and the signals produced from cavitation events have been examined. A directional hydrophone simultaneously monitoring the focal point aided interpretation of the signals detected by the driven bowl. Low-amplitude low-frequency signals appeared on the driven bowl synchronously with the onset of first subharmonic emission in the water at an intensity of 13 W/cm 2. Thc subharmonic increased rapidly with increasing sound intensity and then levelled off. Just before this occurred, the scattering properties of the focal region increased markedly and a cyclic signal, interpreted as indicating the production of clouds of microbubbles when surface oscillations set in on the cavitation bubbles, were detected on the filter circuit. Strongly radiating single cavitation cvcnts lasting for the order of milliseconds were also detected. The amplitude, duration, and rate of occurrence of these events wcrc all one to two orders of magnitude greater in tap than in degassed water. Observation of wind-wave-generated Doppler shifts in surface reverberation lgarashi, Y., Stern, R. Vol 49, No 3, Part 2 (March 1971) pp 802 809 Low-frequency acoustic attenuation in the South Pacific ocean Kibblewhite, A. C., Denham, R. N. Vol 49, No 3, Part 2 (March 1971) pp 8 1 0 815 Dorsal-aspect target strength of an individual fish Love, R. H. Vol 49, No 3, Part 2 (March 1971) pp 816 823 Focusing and refraction of harmonic sound and transient pulses in stratified media Sachs, D. A., Silbiger, A. Vol 49, No 3, Part 2 (March 1971) pp 824 840
245