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Oblique propagation of waves in inhomogeneous media
Oceanographic Abstracts
687
Median grain diameters of the muds are of the order of 1 p; densities vary between 1.20 and 1.40; and porosities (water contents) vary between 80 and 85 per cent. Interbedded with the muds is a widespread layer of diatomite. Peat occurs in the lower part of the Recent sediments, and fine sands, generally micaceous, arc developed in some of the near-shore shallow areas. The Recent sediments rest unconformably on the brownish, tough clays of the Milagro Formation. C-14 determinations on the peats indicate aggs of 7000 to 10,000 years. Paleontological evidence shows that the lake throughout its Recent history has fluctuated from a fresh to a brackish body of water. The maximum salinity was reached during the rise of sea level that accompanied the postglacial climate optimum, when temperatures were warmer than they arc today. The presence of swamp gas in the lake sediments was determined in samples taken with a specially designed core barrel, which secured samples under pressure. Ultrasonic velocities of the lake muds are 3-6 per cent below the velocity of the lake water. On the other hand, the Recent sands and the Milagro clays have velocities more than 7 per cent greater than that of lake water. Ultrasonic velocities were found to be closely related to porosities. This relationship is described by Wood's equation for the velocity of sound in mixtures. Less scattering of points was observed in the acoustic impedance-porosity correlation than in the velocity-porosity correlation. Porosity of the unconsolidated sediments generally increases as the median grain diameter decreases. SASAKI T., S. WATANABE, G. OSmnA, M. KAJOHARA, N. OKAMI and T. TAKAHASHI, 1962. Studies on deep-sea floor current (1). (In Japanese; English summary). J. Oceanogr. Soc., Jap., 20th Ann. Vol., 213-222. Special instruments for the measurement of the deep bottom current were made at the Instituteof Physical and Chemical Research. Some deep bottom current mcasmcments were made with them off Ito City, Shizuoka Prefecture. SCHAEFER K. E. and C. R. CAGEY, 1962. Alveolar pathways during 90-foot, breath-hold dives.
Science, 137 (3535): 1051-1052. The gas tensions of mixed expired and alveolar air were measured at various depths during descent and ascent. A reversed carbon dioxide gradient from the lungs into the blood was demonstrated at the 50 ft depth. At 90 ft, 45 per cent of the pre-dive carbon dioxide content of the lungs had disappeared. There was no indication of a reversed oxygen gradient during ascent. SCHOLTE J. G. J., 1962. Oblique propagation of waves in inhomogeneous media. Geophys. J.,
Roy. Astron., 7 (2): 244-261. The present paper deals with the propagation of plane waves travelling in an arbitrary direction through a medium the elastic parameters and density of which arc a function of the vertical coordinate. Instead of describing the process by differential equations of the second order a system of linear equations is used. This procedure renders it possible to investigate the case where the movement depends in a general way on the time. A method of progressive approximation of the effect of the inhomogeneity has been worked out; this method is generally applicable with the exception of the case where the wave-normal is almost horizontal (the turning-point of a seismic ray). SHULEIKIN V. V., 1962. (Eng. Edit. 1963). Characteristics of certain phenomena in the spectra of light in the depths of the sea. Izv, Akad. Nauk, SSSR, 10: 1404-1415. Eng. Ed.: 10: 875-881. The author demonstrates the need for investigating continuous spectra of light in the depths of the sea, in addition to the measurements of the extinction of light in various narrow regions that are commonly conducted by means of photoelements equipped with light filters. A connection is found between the most probable size of particles which are comparable with the length of the light wave, and the exponent in the formula for light scattering. If the mean square deviation (according to Gauss) is less than 0.2, we can consider that this dependence is the same as it is in the presence of completely uniform particles. ' Standard spectra' are constructed for the ocean-depths with reference to exponent values of 1-5-4.0 at intervals of 0'5, and for various values of the parameter k, which provides the possibility of finding ' standard spectra' in the presence of simple scattering, superimposed on the selective absorption of light in water. Diagrams are constructed which permit the determination o f n and k based on the spectrograms taken in the sea. Ways are outlined for a complete spectral analysis of light in the ocean depths for the clarification of phenomena occurring in sea water. SCHULKIN M., 1963. Eddy viscosity as a possible acoustic absorbtion mechanism in the ocean.
J. Acoust. Soc. Amer., 35 (2): 253-254. Part of the attenuation observed in the propagation of acoustic energy at frequencies below 1 kc/s through the deep ocean is attributed to a relaxation absorption by an eddy viscosity mechanism. A relaxation frequency of about 630 c/s is estimated from the available data, and an absorption dependence on frequency of slightly more than the first power is estimated for the process near the relaxation frequency.
687
Median grain diameters of the muds are of the order of 1 p; densities vary between 1.20 and 1.40; and porosities (water contents) vary between 80 and 85 per cent. Interbedded with the muds is a widespread layer of diatomite. Peat occurs in the lower part of the Recent sediments, and fine sands, generally micaceous, arc developed in some of the near-shore shallow areas. The Recent sediments rest unconformably on the brownish, tough clays of the Milagro Formation. C-14 determinations on the peats indicate aggs of 7000 to 10,000 years. Paleontological evidence shows that the lake throughout its Recent history has fluctuated from a fresh to a brackish body of water. The maximum salinity was reached during the rise of sea level that accompanied the postglacial climate optimum, when temperatures were warmer than they arc today. The presence of swamp gas in the lake sediments was determined in samples taken with a specially designed core barrel, which secured samples under pressure. Ultrasonic velocities of the lake muds are 3-6 per cent below the velocity of the lake water. On the other hand, the Recent sands and the Milagro clays have velocities more than 7 per cent greater than that of lake water. Ultrasonic velocities were found to be closely related to porosities. This relationship is described by Wood's equation for the velocity of sound in mixtures. Less scattering of points was observed in the acoustic impedance-porosity correlation than in the velocity-porosity correlation. Porosity of the unconsolidated sediments generally increases as the median grain diameter decreases. SASAKI T., S. WATANABE, G. OSmnA, M. KAJOHARA, N. OKAMI and T. TAKAHASHI, 1962. Studies on deep-sea floor current (1). (In Japanese; English summary). J. Oceanogr. Soc., Jap., 20th Ann. Vol., 213-222. Special instruments for the measurement of the deep bottom current were made at the Instituteof Physical and Chemical Research. Some deep bottom current mcasmcments were made with them off Ito City, Shizuoka Prefecture. SCHAEFER K. E. and C. R. CAGEY, 1962. Alveolar pathways during 90-foot, breath-hold dives.
Science, 137 (3535): 1051-1052. The gas tensions of mixed expired and alveolar air were measured at various depths during descent and ascent. A reversed carbon dioxide gradient from the lungs into the blood was demonstrated at the 50 ft depth. At 90 ft, 45 per cent of the pre-dive carbon dioxide content of the lungs had disappeared. There was no indication of a reversed oxygen gradient during ascent. SCHOLTE J. G. J., 1962. Oblique propagation of waves in inhomogeneous media. Geophys. J.,
Roy. Astron., 7 (2): 244-261. The present paper deals with the propagation of plane waves travelling in an arbitrary direction through a medium the elastic parameters and density of which arc a function of the vertical coordinate. Instead of describing the process by differential equations of the second order a system of linear equations is used. This procedure renders it possible to investigate the case where the movement depends in a general way on the time. A method of progressive approximation of the effect of the inhomogeneity has been worked out; this method is generally applicable with the exception of the case where the wave-normal is almost horizontal (the turning-point of a seismic ray). SHULEIKIN V. V., 1962. (Eng. Edit. 1963). Characteristics of certain phenomena in the spectra of light in the depths of the sea. Izv, Akad. Nauk, SSSR, 10: 1404-1415. Eng. Ed.: 10: 875-881. The author demonstrates the need for investigating continuous spectra of light in the depths of the sea, in addition to the measurements of the extinction of light in various narrow regions that are commonly conducted by means of photoelements equipped with light filters. A connection is found between the most probable size of particles which are comparable with the length of the light wave, and the exponent in the formula for light scattering. If the mean square deviation (according to Gauss) is less than 0.2, we can consider that this dependence is the same as it is in the presence of completely uniform particles. ' Standard spectra' are constructed for the ocean-depths with reference to exponent values of 1-5-4.0 at intervals of 0'5, and for various values of the parameter k, which provides the possibility of finding ' standard spectra' in the presence of simple scattering, superimposed on the selective absorption of light in water. Diagrams are constructed which permit the determination o f n and k based on the spectrograms taken in the sea. Ways are outlined for a complete spectral analysis of light in the ocean depths for the clarification of phenomena occurring in sea water. SCHULKIN M., 1963. Eddy viscosity as a possible acoustic absorbtion mechanism in the ocean.
J. Acoust. Soc. Amer., 35 (2): 253-254. Part of the attenuation observed in the propagation of acoustic energy at frequencies below 1 kc/s through the deep ocean is attributed to a relaxation absorption by an eddy viscosity mechanism. A relaxation frequency of about 630 c/s is estimated from the available data, and an absorption dependence on frequency of slightly more than the first power is estimated for the process near the relaxation frequency.