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R F Gragg

Publications and source records attributed to R F Gragg.

2 recordsLinked to original sources

Small-slope scattering from rough elastic ocean floors: general theory and computational algorithm.

In this article acoustic scattering by a random rough interface that separates a fluid incident medium from an underlying uniform scattering medium, either fluid or elastic solid, in cases for which the Bragg scale lies within the power-law tail of the roughness spectrum is dealt with. The physical foundation is an inherently reciprocity-preserving, local small-slope theory. A fully bistatic formulation is developed for the scattering strength, together with a robust numerical implementation that allows a wide range of spectral exponent values. The practical result for ocean acoustics is a significantly improved description of the interface component of sea floor scattering. Calculations are presented to demonstrate the advantage of this approach over perturbation theory, and to illustrate its dependence on frequency and environmental parameters as well as its operation in bistatic geometries.

Acoustics↗

Evaluation of a fundamental integral in rough-surface scattering theory.

An algorithm is presented for the numerical evaluation of a fundamental but intractable integral that occurs in the physical theory of scattering from random rough surfaces. It is based on a rational-function approximation to an integrand factor, augmented with techniques for excluding poles and zeros from the path of integration. Examples, complete with error analysis, are provided for cases relevant to acoustic sea-floor and sea-surface scattering.

Journal Article↗