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Inverse problems have a long history in acoustics, optics, electromagnetics and geophysics, but only recently have the signals provided by ocean acoustic sensors become numerous and sophisticated enough to allow for realistic identification of the ocean parameters. Acoustic signals propagating for long distances in the water column and reflections of underwater sound from the ocean boundaries provide novel problems of interpretation and inversion.
The chapters in this volume discuss some of the contemporary aspects of these problems. They provide recent and useful results for bottom recognition, inverse scattering in acoustic wave guides, and ocean acoustic tomography, as well as a discussion of some of the new algorithms, such as those related to matched-field processing, that have recently been used for inverting experimental data. Each chapter is by a noted expert in the field and represents the state of the art. The chapters have all been edited to provide a uniform format and level of presentation.
List of contents
1 What Are We Inverting For?.- 2 Freeze Bath Inversion for Estimation of Geoacoustic Parameters.- 3 Tomographic Inversion on Multiple Receivers/Arrays from Multiple Sources for the Estimation of Shallow Water Bottom Properties.- 4 Nonlinear Optimization Techniques for Geoacoustic Tomography.- 5 Estimating the Impulse Response of the Ocean: Correlation Versus Deconvolution.- 6 Regularized Inversion for Towed-Array Shape Estimation.- 7 Mode-Coupling Effects in Acoustic Thermometry of the Arctic Ocean.- 8 On the Characterization of Objects in Shallow Water Using Rigorous Inversion Methods.- 9 Inverse Boundary-Value Problem for Ocean Acoustics Using Point Sources.- 10 Multidimensional Inverse Problem for the Acoustic Equation in the Ray Statement.- Appendix Ocean Acoustic Tomography: Integral Data and Ocean Models.- A.1 Introduction.- A.2 Sampling Properties of Acoustic Rays.- A.3 Integral Versus Point Data: Information Content in a One-Dimensional Example.- A.4 Integral Versus Point Data: Estimation in a Time-Dependent One-Dimensional Example.- A.5 Discussion.- A.6 Appendix.- A.7 References.- Contributors.
Summary
While it is easy to compute how sound scatters off a given object, the inverse problem of computing the shape of an object from the scattered sound is much more difficult. Only recently have the signals provided by ocean acoustic sensors become good enough to make such "tomography" possible in the ocean. The chapters in this book, each by a noted expert in the field, represent the state of the art; they have all been edited to provide a uniform format and level of presentation.
