Title page for etd-0803115-113703


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URN etd-0803115-113703
Author Hung-ming Lu
Author's Email Address No Public.
Statistics This thesis had been viewed 5587 times. Download 77 times.
Department Institute of Undersea Technology
Year 2015
Semester 1
Degree Master
Type of Document
Language zh-TW.Big5 Chinese
Title The study of acoustic propagation effects induced by sand dunes
and internal waves
Date of Defense 2015-08-12
Page Count 91
Keyword
  • South China Sea
  • internal wave
  • sand dune
  • acoustic model
  • mode coupling
  • Abstract The South China Sea becomes a military and important scientific area now because of its specific location, dynamic water column, active internal wave behavior and significant bathymetry(sand dune topography). The temperature and salinity variability caused by internal wave and the sand dune topography both obviously affect acoustic propagation. This thesis uses acoustic model to explore the acoustic effect in the environment with subaqueous sand dunes and internal wave. The sand dune and internal wave parameters used in acoustic model are referred to 2013 and 2014 South China Sea acoustic experiment data. The simulation results demonstrate that mode 1 energy coupling to higher modes increases as the sand dune amplitude increases, and the coupling mode number increases as wavelength decreases which reveals the wavelength resonance effect. The wavelength resonance effect is more dominant than frequency resonance. With internal wave scale changing, mode 1 energy couple to adjacent higher modes when sound propagate across internal wave. The results demonstrate that coupling mode numbers increase as amplitude increases, and the mode energy coupled in the same mode increase as wavelength increases. Therefore, the results caused by sand dune and internal wave are opposite. This study shows that the variability of sand dunes and internal waves scale cause a part of acoustic mode to exchange energy in each other.
    Advisory Committee
  • Andrea Y.Y. Chang - chair
  • Ruey-Chang Wei - co-chair
  • Linus Y.S. Chiu - advisor
  • Files
  • etd-0803115-113703.pdf
  • Indicate in-campus at 2 year and off-campus access at 3 year.
    Date of Submission 2015-09-04

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