| URN |
etd-0803115-113703 |
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| Author |
Hung-ming Lu |
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| Author's Email Address |
No Public. |
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| Statistics |
This thesis had been viewed 5587 times. Download 77 times. |
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| Department |
Institute of Undersea Technology |
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| Year |
2015 |
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| Semester |
1 |
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| Degree |
Master |
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| Type of Document |
|
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| Language |
zh-TW.Big5 Chinese |
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| Title |
The study of acoustic propagation effects induced by sand dunes
and internal waves |
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| Date of Defense |
2015-08-12 |
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| Page Count |
91 |
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| Keyword |
South China Sea
internal wave
sand dune
acoustic model
mode coupling
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| 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. |
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| Advisory Committee |
Andrea Y.Y. Chang - chair
Ruey-Chang Wei - co-chair
Linus Y.S. Chiu - advisor
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| Files |
Indicate in-campus at 2 year and off-campus access at 3 year. |
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| Date of Submission |
2015-09-04 |
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