Accession Number : ADA305467

Title :   Pulse Propagation in Random Media.

Descriptive Note : Final rept. 1 Jun 92-30 Sep 95,

Corporate Author : VIRGINIA POLYTECHNIC INST BLACKSBURG

Personal Author(s) : Kohler, Werner E.

PDF Url : ADA305467

Report Date : 15 DEC 1995

Pagination or Media Count : 8

Abstract : Four studies involving the propagation of waves in random media were conducted. In the first of these, monoclaromatic elastic plane wave propagation within a randomly layered slab was considered. The issues of mode conversion upon reflection and localization were addressed. Mode conversion refers to the conversion of compressional to shear waves and vice versa by multiple scattering within the layering; localiation is the phenomenon wherein the random layering suppresses transmission of energy through the slab. Explicit characterizations of both phenomena were achieved. The second study addressed the issue of inversion. Radiation from an acoustic point source was assumed incident upon a randomly layered acoustic half space characterized by a deterministic refracting profile. The feasibility of reconstructing this refracting profile using the data recorded by multiple surface sensors from a single random realization was shown. The third study dealt with the issue of layering perturbations. A locally layered acoustic medium was considered, i.e. a medium in which random layering is subjected to controlled deformations orundulations.The basic question considered was the robustness of layering theory, i.e. do localization and other phenomena associated with random layering theory persist when the plane layers are perturbed? The results obtained establish that many of these properties are in fact preserved. The fourth study dealt with propagation loss in a single mode optical fiber. Of interest was the quantitative characterization of transmission loss, which arises from actual dissipation, localization and radiation loss.

Descriptors :   *FIBER OPTICS, *LIGHT SCATTERING, *TRANSMISSION LOSS, SHEAR PROPERTIES, THEORY, WAVE PROPAGATION, PERTURBATIONS, REFRACTION, MULTISENSORS, PLANE WAVES, DETERMINANTS(MATHEMATICS), ELASTIC WAVES.

Subject Categories : Fiber Optics and Integrated Optics

Distribution Statement : APPROVED FOR PUBLIC RELEASE