Article Dans Une Revue Journal of the Acoustical Society of America Année : 2011

Travel-time tomography in shallow water: Experimental demonstration at an ultrasonic scale

Résumé

Acoustic tomography in a shallow ultrasonic waveguide is demonstrated at the laboratory scale between two source-receiver arrays. At a 1/1 000 scale, the waveguide represents a 1.1-km-long, 52- m-deep ocean acoustic channel in the kilohertz frequency range. Two coplanar arrays record the transfer matrix in the time domain of the waveguide between each pair of source-receiver transducers. A time-domain, double-beamforming algorithm is simultaneously performed on the source and receiver arrays that projects the multi-reflected acoustic echoes into an equivalent set of eigenrays, which are characterized by their travel times and their launch and arrival angles. Travel-time differences are measured for each eigenray every 0.1 s when a thermal plume is generated at a given location in the waveguide. Travel-time tomography inversion is then performed using two forward models based either on ray theory or on the diffraction-based sensitivity kernel. The spatially resolved range and depth inversion data confirm the feasibility of acoustic tomography in shallow water. Comparisons are made between inversion results at 1 and 3 MHz with the inversion procedure using ray theory or the finite-frequency approach. The influence of surface fluctuations at the air- water interface is shown and discussed in the framework of shallow-water ocean tomography.

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hal-00625344 , version 1 (21-09-2011)

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Philippe Roux, Ion Iturbe, Barbara Nicolas, Jean Virieux, Jerome I. Mars. Travel-time tomography in shallow water: Experimental demonstration at an ultrasonic scale. Journal of the Acoustical Society of America, 2011, 130 (3), pp.1232-1241. ⟨10.1121/1.3621271⟩. ⟨hal-00625344⟩
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