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Near and far EMI field analyses in a conducting environment to enhance underwater UXO detection

Proc. SPIE 7303, 73030D (2009); http://dx.doi.org/10.1117/12.819059

Monday 13 April 2009
Orlando, FL, USA
Detection and Sensing of Mines, Explosive Objects, and Obscured Targets XIV
Russell S. Harmon, J. Thomas Broach, John H. Holloway, Jr.
Fridon Shubitidze and Irma Shamatava

Dartmouth College (USA) and Sky Research, Inc. (USA)

Ben Barrowes

U.S. Army Engineer Research and Development Ctr. (USA)

Juan Pablo Fernández

Sky Research, Inc. (USA)

Kevin O'Neill

Sky Research, Inc. (USA) and U.S. Army Engineer Research and Development Ctr. (USA)

The underlying physics of low frequency EMI scattering phenomena in underwater environments from highly conducting and permeable metallic objects is analyzed using an approach that combines the method of auxiliary sources and a surface impedance boundary condition. The combined algorithm solves EMI boundary-value problems by representing the electromagnetic fields in each domain of the structure under investigation by a finite linear combination of analytical solutions of the relevant field equations, corresponding to elementary sources situated a small distance away from the boundaries of each domain. Numerical experiments are conducted for homogeneous and multilayer targets of canonical (spheroidal) shapes subject to frequency- or time-domain illumination, as well as for heterogeneous UXO like targets, to demonstrate: (a) how marine environments change EMI sensor performance and associated processing approaches for detecting highly conducting and permeable metallic objects underwater, and (b) what are the EMI sensors detectability limits. Near and far EMI field and induced eddy-current distributions are presented to help gain insight into underwater EMI scattering phenomena. Particularly, the results illustrate coupling effects between the object and its surrounding conductive medium, especially at high frequencies (early times for time-domain sensors). The results also suggest that this coupling depends on the object's material properties, the conductivity of the medium, and the distance between the sensor and the object's center.

© 2009 COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

History
Online May 04, 2009
Citation
Fridon Shubitidze, Ben Barrowes, Irma Shamatava, Juan Pablo Fernández and Kevin O'Neill, "Near and far EMI field analyses in a conducting environment to enhance underwater UXO detection", Proc. SPIE 7303, 73030D (2009); http://dx.doi.org/10.1117/12.819059

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