Title page for etd-0823110-183618


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URN etd-0823110-183618
Author Jian-Yi Wu
Author's Email Address No Public.
Statistics This thesis had been viewed 5537 times. Download 1142 times.
Department IAMPUT
Year 2009
Semester 2
Degree Master
Type of Document
Language zh-TW.Big5 Chinese
Title Noise Signatures Analysis of Nearshore Breaking Wave
Date of Defense 2010-07-27
Page Count 67
Keyword
  • ambient noise
  • breaking wave heights
  • surf zone
  • breaking wave periods
  • Abstract  The ocean ambient noise of coast is mainly influenced by sea waves, boats or ships, or human’s coast activities. Among them, most of the ambient noise is from the breaking wave noise caused by wind, and its frequency range is quite wide (0.5~50 kHz). The breaking wave noise mechanism of surf zone is very complex, and has a variety of signal features. In this research, the location is at the Sizih Bay near Kaohsiung Harbor. Hydrophone was used to collect the noise and the wave motion process of surf zone was recorded simultaneously with a digital video camera. It was shown from the experiment results, as the wave evolved in the surf zone, it would eventually become unstable and collapsed, so a large amount of air would be trapped in water and forming bubble clouds. The oscillating bubble cloud from breaking wave would generate high frequency sound. The results also indicated that when breaking wave reached the location hydrophone, a wide band pulse sound was generated with a level as high as 120 dB. In the analysis of each frequency (1k, 2k, 3k, 4k, 5k Hz), due to the oscillating effects air bubbles after breaking wave, the noise level at 2~5k Hz were higher as compared to that without breaking wave passing the hydrophone. The last result was also validated by the time integral of the noise energy through out the wave evolution. In addition to the process of breaking waves and residual air bubbles under breaking waves contributing to the breaking wave source, for example discussed in the study breaking wave’s period and breaking wave height, the results from these two studies found, when the longer the breaking wave period , the breaking wave SPL will be bigger with the longer the breaking wave period. And in the breaking wave height, when the breaking wave height much higher, breaking wave SPL will be much bigger too. And learned from these two conclusions , breaking wave periods and height will make the breaking waves source level caused by changes.
    Advisory Committee
  • Hu-Guang Yang - chair
  • Hiang-Zhi Zhan - co-chair
  • Ruey-Chang Wei - advisor
  • Files
  • etd-0823110-183618.pdf
  • indicate access worldwide
    Date of Submission 2010-08-23

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