A Comparison of two acoustic techniques for the measurement of bubble distributions in the ocean
Date
1995
Authors
Mao, Victor Yi-Xin
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Abstract
This thesis undertakes part of the work of developing a novel system consisting of an acoustical resonator sensor and a sound speed sensor for measuring bubble populations in the water. The principles of the sound speed sensor and the acoustical resonator are presented. To estimate sound speed anomaly, which can be used to infer bubble populations in bubbly water, some data processing techniques are used and prove to be very effective. Besides presenting a series of laboratory tests of the instrumentation, a successful field experiment conducted in the ocean is reported, in which the newly developed instrument was used. The results obtained from both sensors are compared. As one of the most important contributions of this thesis, a clear analysis has been given of the propagation of a short acoustical pulse in bubbly water. Some new equations are derived, which provide a useful theory to improve the accuracy of bubble population estimates. Field results are interpreted with the aid of the theory.