Direct methods for inverse scattering with time dependent and reduced data
Date
2017
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Publisher
University of Delaware
Abstract
This thesis is focused on the motion of acoustic waves through penetrable media, and the use of such waves to reconstruct material properties of the fluid through which the waves are moving. The reconstruction methods developed in this thesis fall under the category of qualitative inversion methods and, as such, are fast and mathematically justified. Unlike in typical qualitative methods, however, these new methods require only small amounts of scattered field data to be collected. In particular, we demonstrate that with both far field time harmonic data and near field time dependent data, the location of weakly scattering point obstacles can be reconstructed with reduced data collection requirements compared to typical qualitative schemes. We give full mathematical justification for the time harmonic method and partial justification for the time dependent method. We also analyze the transmission eigenvalue problem for weakly scattering media, proving that, under this assumption, transmission eigenvalues are discrete and can sometimes have complex part which grows without bound. Finally, we introduce a fast method for simulating time harmonic and time dependent acoustic wave scattering and apply this method to optimization schemes for reconstructing penetrable media based on scattered field data.
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Keywords
Applied sciences, Acoustic waves, Scattered field data