Title page for etd-0703107-034802


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URN etd-0703107-034802
Author Shih-Feng Yang
Author's Email Address No Public.
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Department Undersea Technology
Year 2006
Semester 2
Degree Master
Type of Document
Language zh-TW.Big5 Chinese
Title The Study of Inverting Sediment Sound Speed Profile Using a Geoacoustic Model for a Nonhomogenous Seabed
Date of Defense 2007-06-20
Page Count 127
Keyword
  • Geoacoustic inversion
  • generalized-exponential and inverse-square functions
  • parameter sensitivity analysis
  • uncertainty analysis
  • statistical estimation of inverted sound speed profile
  • Abstract The objective of this thesis is to develop and implement an algorithm for inverting the sound speed profile via estimation of the parameters embedded in a geoacoustic model. The environmental model inscribes a continuously-varying marine sediment layer with density and sound speed distributions represented by the generalized-exponential and inverse-square functions, respectively. Based upon a forward problem of plane-wave reflection from a non-uniform sediment layer overlying a uniform elastic basement, an inversion procedure for estimating the sound speed profile from the reflected sound field under the influence of noise is established and numerically implemented. The inversion invokes a probabilistic approach quantified by the posterior probability density for measuring the uncertainties of the estimated parameters from synthetic noisy data. Preliminary analysis on the solution of the forward problem and the sensitivity of the model parameters is first conducted, leading to a determination of the parameters chosen for inversion in the ensuing study. The parameter uncertainties referenced 1-D and 2-D marginal posterior probability densities are then examined, followed by the statistical estimation for the sound speed profile in terms of 99 % credibility interval. The effects of, the signal-to-noise ratio (SNR), the dimension of data vector, the region in which the data sampled, on the statistical estimation of sound speed profile are demonstrated and discussed.
    Advisory Committee
  • Ching-Jer Huang - chair
  • Barry Ma - co-chair
  • Jin-Yuan Liu - advisor
  • Chen-Fen Huang - advisor
  • Files
  • etd-0703107-034802.pdf
  • indicate in-campus access immediately and off_campus access in a year
    Date of Submission 2007-07-03

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