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

## 4pSA3. Scattering from complex elastic structures.

**Douglas M. Photiadis
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*Naval Res. Lab., Washington, DC 20375-5000
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The scattering cross section of elastic structures is modified in a
nontrivial fashion by the presence of effectively random internal structure. The
locus of the highlights in frequency-angle space can often be modeled reasonably
by considering the behavior of the associated average structure, but the
influence of the internal structure on the levels of the scattering cross
section cannot be determined in this way. In terms of the development of
effective scattering models, the mean Green's function does not contain enough
information in this context and higher-order averages are required, at a minimum
the mean intensity . The perturbative computation of such quantities is
relatively well understood for a medium which is uniform, but for the structures
of most interest, those whose properties on average vary spatially, the problem
is much more difficult. The theoretical approach to the solution in this case
will be discussed, and the approximate results obtained will be compared with
the results from direct Monte Carlo simulations.