Can maximum likelihood estimators improve genetic algorithm search in geoacoustic inversion ?

S.M. Jesus
UCEH - Universidade do Algarve,
Campus de Gambelas, PT-8000, Faro, Portugal.

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Ref.: Journal of Computational Acoustics, Vol.6, nos.1 & 2, pp 73-82, 1998.


The principles for estimating seafloor parameters via matched-field processing (MFP) based techniques are now well known. In pure MFP, source localization is often seen as a range-depth estimation problem while the use of MFP on geoacoustic estimation generally involves a computationnaly intensive optimization procedure. In the last few years, most effort has been devoted to developing new or improving existing search procedures to solve the optimization problem and little, or no, attention has been given to the ensemble MFP-optimization treating it as a single technique. The question addressed in this paper is centered on the relation between the MFP parameter estimator technique, defining the objective function, and the search procedure used to optimize it. In particular, we are interested in questions like: can a faster search or more accurate estimate be achieved with a ``peaky'' surface instead of a flat and ambiguous surface ? Is the inversion process affected by cross-frequency estimators and model mismatch ? Does the search procedure need to be modified, and if yes how, to account for this ``peaky'' surface navigation ? This paper attempts to answer these and other related questions in the context of the June'97 geoacoustic inversion workshop data set.

ACKNOWLEDGMENT: this work was partially supported by the EU project MAS2-CT920022.