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51 
A numerical evaluation of the Helmholtz integral in acoustic scatteringSandness, Gerald Allyn, January 1973 (has links)
Thesis (Ph. D.)University of WisconsinMadison, 1973. / Vita. Typescript. eContent providerneutral record in process. Description based on print version record. Includes bibliographical references.

52 
Quantifying hurricane wind speed with undersea sound /Wilson, Joshua David. January 1900 (has links)
Thesis (Ph. D.)Joint Program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Dept. of Mechanical Engineering; and the Woods Hole Oceanographic Institution), 2006. / Includes bibliographical references (p. 155169).

53 
Estimation and tracking of rapidly timevarying broadband acoustic communication channels /Li, Weichang. January 2006 (has links)
Originally issued as the author's thesis (Ph. D.)Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 2006. / "February 2006". "Doctoral dissertation." "Department of origin: Applied Ocean Physics and Engineering." "Joint Program in Oceanography/Applied Ocean Science and Engineering"Cover. Bibliography: p. 197206.

54 
Laboratory studies of acoustic scattering : shape perturbations and material anisotropyChinnery, Paul Anthony January 1995 (has links)
No description available.

55 
Quantitative measurements of marine acoustic scattering from zooplanktonic organismsBeamish, Peter January 1969 (has links)
The purposes of this research have been to determine a) the basic physical causes of acoustic scattering from zooplanktonic organisms and b) necessary criteria for future acoustic studies involving these animals.
In situ measurements at 102 kHz have been made of the scattering of sound from a volumetric distribution of a zooplanktonic organism, the euphausiid. Quantitative information was recorded on analog magnetic tape and subsequently converted to digital form for analysis.
Based on simultaneous measurements of side and back scattering from euphausiids and on a mathematical model, fourfifths of the scattered sound is considered to be caused by the compressibility contrast between the animals and the sea water. The remaining onefifth is attributed to density contrast.
Acoustic energy distribution curves are characteristic of the number and size of the animals contained in the small volume of the ocean that was studied. Acoustic counting of the animals gave results that compared favourably with simultaneous controlled net sampling.
The back scattering crosssection of a typical euphausiid at 102 kHz has been found to be 1.4 x 10⁻⁴ cm² . Based on this value it is possible to predict the optimum frequency and intensity of incident sound for future acoustic studies involving these animals. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

56 
A study of the relationship between zooplankton and highfrequency scattering of underwater soundPieper, Richard Edward January 1971 (has links)
Quantitative volumescattering measurements were compared to the distribution of euphausiids in Saanich Inlet, British Columbia. Scattering was recorded at 42, 107, and 200 kHz from the depths of high euphausiid concentrations, and volumescattering coefficients were determined. No scattering from euphausiids was recorded by a 11 kHz echosounder. Daily variations in the volumescattering coefficients, m(Δz), generally compared well with variations in the concentration of euphausiids. The daily behaviour of the highfrequency scattering layer., and therefore m(Δz) and the concentration of euphausiids, was influenced by moonlight and weather conditions as well as the presence or absence of an oxycline in the inlet.
In the absence of an oxycline conditions would have been closer to conditions in the open ocean. Under these circumstances euphausiid concentrations and m(Δz) were low in the mornings and gradually increased throughout the day; the highfrequency scattering layer consolidated. During the evening migration, the layer became more diffuse, and the number of euphausiids per cubic metre decreased.
The scattering crosssection, σ (cm²), of a euphausiid was found to increase with the average dry weight and length, and with increased frequency. For each cruise σ was approximately one order of magnitude apart at the three frequencies. The values of σ (in cm²) ranged from 4.81 x 10⁻⁵ to 5.21 x 10⁻³(200 kHz), 5.49 x 10⁻⁶ to 3.99 x 10⁻⁴ (107 kHz), and 2.30 x 10⁻⁷ to 3.67 x 10⁻⁵ (42 kHz). / Science, Faculty of / Zoology, Department of / Graduate

57 
A Simplification of Underwater Acoustic EquationsMiddleton, Morris G. 01 January 1973 (has links)
This Research Report presents some of the equations of underwater acoustics that relate to the signal excess noise received by a transducer. The basic structural equation is developed, as are defining equations for each term in that equation. An analysis is performed utilizing typical values to ascertain if the elements of the structural equation can be simplified. Results delineate that several terms of that equation can be neglected while maintaining a relative high degree of accuracy.

58 
The effect of a random ocean on acoustic intensity fluctuationsCampbell, Gordon January 1994 (has links)
No description available.

59 
Geoacoustic inversion in shallow waterCox, Benjamin Timothy January 1999 (has links)
No description available.

60 
Nonlinear ray dynamics in underwater acousticsBódai, Tamás January 2008 (has links)
This thesis is concerned with longrange sound propagation in deep water. The main area of interest is the stability of acoustic ray paths in wave guides in which there is a transition from single to double duct sound speed profiles, or viceversa. Sound propagation is modelled within a ray theoretical framework, which facilitates a dynamical systems approach of understanding longrange propagation phenomena, and the use of its tools of analysis. Alternative reduction techniques to the Poincaré sections are presented, by which the stability of acoustic rays can be graphically determined. Beyond periodic driving, these techniques prove to be useful in case of the simplest quasiperiodic driving of the ray equations. One of the techniques facilitates a special representation of ray trajectories for periodic driving. Namely, the space of sectioned trajectories is partitioned into nonintersecting regular and chaotic regions as with the Poincaré sections, when quasiperiodic and chaotic trajectories are represented by curve segments and area filling points, respectively. In case of the simplest quasiperiodic driving – speaking about the same technique – regular trajectories are represented by curves similar to Lissajous curves, which are opened or closed depending on whether the two driving frequencies involved make relative primes or not. It is confirmed for a perturbed canonical profile that the background sound speed structure controls ray stability. It is also demonstrated for a particular double duct profile, when the singularity of the nonlinearity parameter for the homoclinic trajectory associated with this profile refers to the strong instability of corresponding perturbed trajectories.

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