Accession Number : ADA307862

Title :   Progress Report for The Catholic University of America Grant N0OO14-94-1-02O1.

Descriptive Note : Progress rept. 1 Jul-31 Dec 95,

Corporate Author : CATHOLIC UNIV OF AMERICA WASHINGTON DC DEPT OF ELECTRICAL ENGINEERING

Personal Author(s) : Beran, M. J.

PDF Url : ADA307862

Report Date : 31 DEC 1995

Pagination or Media Count : 4

Abstract : The calculations for considering linear sound-speed profiles in channels have been generalized to treat piece-wise linear sound-speed profiles. Calculation of the scattering coefficients for the linear profile was begun. The case of a channel with a complex bottom impedance condition was also under investigation. As a result of the fact that the eigenvalues are now complex, a diffusion-like term has been added to the governing coherence equations. We began studies of methods to calculate the effect of this term since the governing equations can no longer be reduced to a set of ordinary differential equations for cylindrically symmetric sources. The work on the two- frequency coherence equations continued and the conditions for their validity were carefully considered. It was shown that for large normalized frequency differences the governing equations simplified considerably. We also began looking for a suitable asymptotic formulation to determine the effect of the small normalized frequency differences for very long propagation distances.

Descriptors :   *ACOUSTIC SCATTERING, *UNDERWATER ACOUSTICS, MATHEMATICAL MODELS, ACOUSTIC WAVES, NUMERICAL ANALYSIS, REFRACTIVE INDEX, EIGENVECTORS, SHALLOW WATER, WAVE PROPAGATION, APPROXIMATION(MATHEMATICS), DIFFERENTIAL EQUATIONS, ACOUSTIC VELOCITY, SPECTRUM ANALYSIS, ACOUSTIC DATA, CHANNELS(WATERWAYS), ACOUSTIC IMPEDANCE.

Subject Categories : Acoustics

Distribution Statement : APPROVED FOR PUBLIC RELEASE