ASA 130th Meeting - St. Louis, MO - 1995 Nov 27 .. Dec 01

1aPA14. Local temporal variance of Wigner's distribution.

David H. Hughes

Code 7132, Naval Res. Lab., Washington, DC 20375-5000

Lamb wave resonances on submerged spherical shell are analyzed via the local temporal variance of the signal Wigner distribution. The local resonance widths are obtained by approximating the local resonance contribution to the farfield backscattering form function of a particular Lamb wave as a resonance of the single Breit--Wigner type. The half-width of the resonance is approximately proportional to the inverse of the square root of the local temporal variance evaluated at resonance. This discrete distribution is compared against the continuous half-width distribution as rendered by the ray acoustic approximation for the particular Lamb wave under study. [Work supported by ONR.]