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Journal ArticleDOI

Survey of Literature on Reflection and Scattering of Sound Waves at the Sea Surface

01 May 1970-Journal of the Acoustical Society of America (Acoustical Society of America)-Vol. 47, pp 1209-1228
TL;DR: The problem of diffraction of waves at uneven surfaces has received increasing attention in the past 15-20 years as discussed by the authors, which has resulted in a large number of reports and papers in the open literature.
Abstract: The problem of diffraction of waves at uneven surfaces has received increasing attention in the past 15–20 years. This has resulted in a large number of reports and papers in the open literature. In this review article most of the publications dealing with sound waves and pressure release surfaces (both theoretical and experimental) that appeared up to the beginning of 1969 are mentioned as references. They are classified by subject, and the main currents in the literature (Rayleigh and Uretsky method for sinusoidal boundaries, Eckart theory with Kirchhoff approximation for random surfaces, experiments at sea) are analyzed and discussed. General trends, relations between studies, agreements, and contradictions are mentioned. It is found that nearly all of the publications cover only part of the problem: although the wave diffraction at rough surfaces is a function of three basic quantities simultaneously (i.e. time, frequency of incident wave, and geometry), most of the papers deal with only one or anothe...

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Citations
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Journal ArticleDOI
Y. W. Lee, V. E. Benes1

709 citations

Journal ArticleDOI
TL;DR: An overview is given over some of the most widely used numerical techniques for solving the electromagnetic scattering problem that start from rigorous electromagnetic theory.
Abstract: An overview is given over some of the most widely used numerical techniques for solving the electromagnetic scattering problem that start from rigorous electromagnetic theory. In particular, the theoretical foundations of the separation of variables method, the finite-difference time-domain method, the finite-element method, the method of lines, the point matching method, the method of moments, the discrete dipole approximation, and the null-field method (or extended boundary condition method) are reviewed, and the advantages and disadvantages of the different methods are discussed. Aspects concerning the T matrix formulation and the surface Green's function formulation of the electromagnetic scattering problem are addressed.

442 citations

Journal ArticleDOI
01 Nov 1981
TL;DR: This paper is a tutorial which describes "main stream" sonar digital signal processing functions along with the associated implementation considerations to promote further cross-fertilization of ideas amongdigital signal processing applications in sonar, radar, speech, communications, seismology, and other related fields.
Abstract: This paper is a tutorial which describes "main stream" sonar digital signal processing functions along with the associated implementation considerations. The attempt is to promote further cross-fertilization of ideas among digital signal processing applications in sonar, radar, speech, communications, seismology, and other related fields.

431 citations

Journal ArticleDOI
TL;DR: In this paper, the authors used linear perturbation theory to show that the reflection coefficient is both oscillatory in the quotient of the length of the patch and the surface wavelength, and also strongly dependent upon the quotients of the surface and bed wavelengths.
Abstract: Surface waves travelling in water of finite depth may be scattered by a region of undulating bottom topography. The present study is concerned with the idealized two-dimensional situation in which long-crested surface waves are incident upon a patch of long-crested regular bottom ripples. The principal question examined concerns the amount of incident wave energy that is reflected by the ripple patch. Linear perturbation theory is used to show that the reflection coefficient is both oscillatory in the quotient of the length of the patch and the surface wavelength, and also strongly dependent upon the quotient of the surface and bed wavelengths. In particular, there is a Bragg resonance between the surface waves and the ripples, which is associated with the reflection of incident wave energy. A secondary question concerns the nature of the wave field in the immediate vicinity of the ripple patch. In resonant cases, it is shown how the partially standing wave on the upwave side of the ripple patch gives way, in an almost linear manner over the patch itself, to a progressive transmitted wave on the downwave side. The theoretical predictions are compared with an extensive set of laboratory observations made in a wave tank. Comparisons relating both to the reflection coefficient, and also to the wave field over the ripple patch, are shown to give consistently good agreement. Finally, the implications of the results for sediment transport on an erodible bed are examined.

321 citations

Journal ArticleDOI
TL;DR: In this paper, the authors reviewed the Rayleigh hypothesis in relation to scattering by periodic surfaces, aperiodic surfaces, and bounded, two-dimensional bodies, and provided conditions for its validity for a sinusoidal grating.
Abstract: The Rayleigh hypothesis is reviewed in relation to scattering by periodic surfaces, aperiodic surfaces, and bounded, two-dimensional bodies. Conditions for its validity are described, and explicit results are quoted for a sinusoidal grating. Some methods to solve scattering problems for periodic surfaces are outlined. One particular procedure for periodic surfaces and bounded scatterers is examined in detail. This involves an expansion for the scattered field in terms of the same sets of elementary wavefunctions that occur in connection with the Rayleigh hypothesis. The coefficients are determined by satisfying the boundary condition in the least-squares sense. It is shown that this solution converges uniformly to the scattered field at all points exterior to the boundary of the scatterer. Necessary completeness properties of the sets of wavefunctions are established in the appendices.

266 citations

References
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Book
01 Jan 1963
TL;DR: The scattering of electromagnetic waves from rough surfaces PDF is available at the online library of the University of Southern California as mentioned in this paper, where a complete collection of electromagnetic wave from rough surface books can be found.
Abstract: THE SCATTERING OF ELECTROMAGNETIC WAVES FROM ROUGH SURFACES PDF Are you looking for the scattering of electromagnetic waves from rough surfaces Books? Now, you will be happy that at this time the scattering of electromagnetic waves from rough surfaces PDF is available at our online library. With our complete resources, you could find the scattering of electromagnetic waves from rough surfaces PDF or just found any kind of Books for your readings everyday.

3,568 citations

Journal ArticleDOI
TL;DR: In this paper, a method was developed for interpreting the statistics of the sun's glitter on the sea surface in terms of the statistic of the slope distribution, which was applied to aerial photographs taken under carefully chosen conditions in the Hawaiian area.
Abstract: A method is developed for interpreting the statistics of the sun’s glitter on the sea surface in terms of the statistics of the slope distribution. The method consists of two principal phases: (1) of identifying, from geometric considerations, any point on the surface with the particular slope required for the reflection of the” sun’s rays toward the observer; and (2) of interpreting the average brightness of the sea surface in the vicinity of this point in terms of the frequency with which this particular slope occurs. The computation of the probability of large (and infrequent) slopes is limited by the disappearance of the glitter into a background consisting of (1) the sunlight scattered from particles beneath the sea surface, and (2) the skylight reflected by the sea surface.The method has been applied to aerial photographs taken under carefully chosen conditions in the Hawaiian area. Winds were measured from a vessel at the time and place of the aerial photographs, and cover a range from 1 to 14 m sec−1. The effect of surface slicks, laid by the vessel, are included in the study. A two-dimensional Gram-Charlier series is fitted to the data. As a first approximation the distribution is Gaussian and isotropic with respect to direction. The mean square slope (regardless of direction) increases linearly with the wind speed, reaching a value of (tan16°)2 for a wind speed of 14 m sec−1. The ratio of the up/ downwind to the crosswind component of mean square slope varies from 1.0 to 1.9. There is some up/downwind skewness which increases with increasing wind speed. As a result the most probable slope at high winds is not zero but a few degrees, with the azimuth of ascent pointing downwind. The measured peakedness which is barely above the limit of observational error, is such as to make the probability of very large and very small slopes greater than Gaussian. The effect of oil slicks covering an area of one-quarter square mile is to reduce the mean square slopes by a factor of two or three, to eliminate skewness, but to leave peakedness unchanged.

2,270 citations

Journal ArticleDOI
Y. W. Lee, V. E. Benes1

709 citations

Journal ArticleDOI
TL;DR: In this paper, a theoretical model is used to investigate the geometrical self-shadowing of a surface described by Gaussian statistics, and expressions for various shadowing probabilities as functions of the parameter characterizing surface roughness and of the angle of incidence of the illuminating beam.
Abstract: In the context of the backscattering of waves from a random rough surface, a theoretical model is used to investigate the geometrical self-shadowing of a surface described by Gaussian statistics. Expressions are derived for various shadowing probabilities as functions of the parameter characterizing surface roughness and of the angle of incidence of the illuminating beam. The theoretical shadowing functions compare closely with those obtained experimentally from a recent computer simulation of a Gaussian surface.

469 citations

Journal ArticleDOI
TL;DR: In this paper, the average number of specular points per unit area for a two-dimensionalally rough surface is derived in terms of the surface statistics, and expressions for the average of the product of the principal radii of curvature of the specular point are also obtained.
Abstract: The average number of specular points per unit area for a two-dimensionally rough surface is derived in terms of the surface statistics. Expressions for the average of the product of the principal radii of curvature of the specular point are also obtained. These quantities are then substituted into the average scattering cross section per unit area derived from the stationary-phase approach, and two probability models are considered. The results are general and apply to bistatic as well as backscatter, and are valid for finitely as well as perfectly conducting surface materials.

388 citations