Title page for etd-1101114-103539


[Back to Results | New Search]

URN etd-1101114-103539
Author Yu-ying Lien
Author's Email Address No Public.
Statistics This thesis had been viewed 5569 times. Download 418 times.
Department Institute of Undersea Technology
Year 2014
Semester 1
Degree Master
Type of Document
Language zh-TW.Big5 Chinese
Title Acoustic Propagation Effect due to Subaqueous Sand Dunes in the South China Sea
Date of Defense 2014-11-17
Page Count 76
Keyword
  • sand dune
  • towed source
  • multipath effect
  • sand dune acoustic experiment
  • travel time
  • acoustic propagation
  • Abstract To study the characteristics of sand dunes in the South China Sea (SCS) and its effects on sound propagation, the pilot experiment of the Acoustic Sand Dune Experiment was carried on in May 2012, used a multi-beam echo sounder collecting the topographic data. The intensive observation phase of the Sand Dune Acoustic Experiment in May 2013 is planed based on the resluts of the pilot experiment, which achieve finer measurement: multi-beam echo sounder. The characteristics of sand dunes can be obtained by comparing the results of 2012 and 2013. Furthermore, the acoustic experiment was conducted in 2013; the acoustic recorders were deployed at the center and the source was towed with a 5 km radius circle to obtain the energy fluctuation under different sand dunes structure. This data was used to discuss the impact on multipath effect and energy distribution caused by sand dunes. Moreover, two numerical models: BELLHOP and RAM-PE were applied to model the propagation effects in sand dune field. The results shows that sand dunes on the upper continental slope in SCS were extended in the northeast-southwest direction; and most of its amplitude are less than 10 m, only few were observed over 20 m. From the survey results of this two years, we can see the amount of variation was small and from experiment data and numerical modeling, we can see that the sand dunes will have significant impact on multipath effect, ans also cause a great loss near sea surface. In addition, without considering the sand dunes, when the terrain change from upslope to downslope, signal energy will concentrate on the surface layer of water. This research can be used as a reference for future experiments, and be further applied to discuss the acoustic communication performance caused by the sand dunes.
    Advisory Committee
  • Hsin-Hung Chen - chair
  • Andrea Y.Y. Chang - co-chair
  • Chi-Fang Chen - co-chair
  • Linus Y.S. Chiu - advisor
  • Files
  • etd-1101114-103539.pdf
  • Indicate in-campus at 3 year and off-campus access at 3 year.
    Date of Submission 2014-12-03

    [Back to Results | New Search]


    Browse | Search All Available ETDs

    If you have more questions or technical problems, please contact eThesys