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The Establishment of Sihziwan Marine Test Field: Environmental AnalysisHsu, Teng-yi 03 September 2007 (has links)
The so-called "Marine Testing Field (MTF)" is a concept to set up a natural site so that a laboratory experiment may be implemented directly at sea. In viewing the geographical advantage of National Sun Yat-sen University (NSYSU), an MTF has been proposed near the Shziwan bay area, which is particularly suitable to conduct research on near shore processes and harbor monitoring and protection. The purpose of this study is implemented the first phase towards the establishment of Shziwan MTF, that is, to conduct a complete survey of this area, including topological, morphological, geological, and dynamical properties of this area. The survey employs various equipment including sidescan sonar, subbpttom profiler, multibeam system, and seabed sampling, etc. To achieve a good quality, the survey routes were carefully planned, and 10 seabed samples were taken. The results have shown that the slope of the seafloor is about 145:1, indicating that the area has a very slow varying topography. Sidescan images have been carefully analyzed, and several objects on the seabed have been identified; furthermore, the subbottom images have shown layering structure in this area. The seabed sampling shows that the seabed is mostly consisted of fine sand with average particle size of about 0.263 mm. Overall, the field already explored shows that it is about 4116725m2 in area, in which 88.1% is sand, 7.2% sand with ripple marks, and 4.7% rocks.
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The Study of Reverberation in the Sizih Bay Marine Test FieldLin, Yu-Te 28 July 2011 (has links)
Reverberation is the phenomenon when the sound source transmits and causes scattering in active sonar system. This kind of effects often produced in the waveguide, resulting signal interference and signal mask issues. Reverberation can affect the signal to noise ratio, thus understanding the characteristic of environmental reverberation is important. In recent years, there were many studies for the Sizihwan Bay Marine Test Field (MTF), including environmental surveys, Harbor defense and acoustic inversion, however the issue related to reverberation has not been explored. The purpose of this study is to research reverberation in the MTF and focusing on volume reverberation and surface reverberation. In the past, the experiment of Underwater Intruder Detection with active sonar system demonstrated the reverberation in Kaohsiung second harbor. Therefore, this research is about using the experimental data to questions about volume reverberation. Results show, volume reverberation in the port area caused by ship, boundaries, current, impurities in water and biota. On the other hand surface reverberation, this study focusing on numerical simulation, match the results of experimental. Numerical results of RMS height, correlation length and frequency affect the reverberation intensity, but it does not identify the phenomenon of reverberation in experimental results, mainly is the intensity of the source is not enough. This study combined with simulation and experiment, and overviewed the reverberation properties in MTF. Also provided suggestions for following studies.
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A Feasibility Test of Acoustic Tomography on Current Estimate in a Shallow Water EnvironmentKuo, Nai-Tsung 03 August 2012 (has links)
Underwater communication is an important research of applied underwater acoustic since sound wave is the only effective way of transmitting messages under water. Underwater communication has always been a complicated problem especially in the shallow water environment due to the influence of multipath propagation. In the past, research on underwater communication had been done mostly by numerical simulation or laboratory experiments instead of doing in real oceanic areas. As a result, several research teams such as the Institute of Oceanography in Taiwan University, the Naval Research Laboratory and the acoustic laboratory of National Sun Yat-sen University Institute of Applied Marine Physics and Undersea Technology had executed a one-week real oceanic area experiment of underwater networking, communication, and acoustical tomography in Sizih Bay Marine Test Field. The experiment adopted 9 sets of underwater modem distributed within the range of 30 square kilometer to transmit, receive signals and collect CTD data. This research adopted part of the data gained from the experiment mentioned above to progress the feasibility test of acoustic tomography on current estimate to shallow water environment. By transmitting and receiving signals between stations, This research study the travel time difference between transmitting signals forward and backward caused by the flow field when using high frequency source in shallow water environment. This research estimated the average current speed and compared it to the weather buoy data from the Harbor and Marine Technology Center. This research discovered that most of the estimated results correspond to the weather buoy's ADCP data. Finally, this research adopted the method which does not require complex mathematics operation to estimate the two-dimensional flow field, and probe into what influence the angle between stations would bring to the deviation of estimating flow speed by using the Monte Carlo method.
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A Very Shallow Water Acoustic Propagation Experiment in the Si-Tzi Marine Test FieldXiao, Ming-Heng 26 August 2009 (has links)
The purpose of this study explores the sound propagation in very shallow water to understand the environment quality of the Si-Tzi Marine Test Field. Very shallow water acoustics characterized by that sound wave will have a dramatic interaction between the bottoms and the propagation of wave and bottom with a high degree of correlation. Those types of environment are concentrated in the west coast of Taiwan.
Analysis of actual acoustic data from the ocean obtain and to use "OASES" simulation that an applied acoustic tool. Expect to understand the phenomenon of water acoustic propagation in the very shallow. The Si-Tzi marine test field had detailed environmental information by previously study. In experiment process, the hydrophone "iTC-6050c" receiving broadband sound source "UW350" signal. The use of personal computer with DAQ card for data acquisition and control. The source in the research vessel was moored 20 m below sea, at the same time to launch three consecutive single (frequency signal 350 Hz, 800 Hz, and 1250 Hz). Reception of signals in order to drift the way. Measured at different frequencies in very shallow water of the transmission loss. The results showed that the results of the current measurement and simulation in line with the follow-up study will be measured "transmission loss" to do to Inversion for geoacoustic parameters in very shallow water.
Then obtained "geoacoustic parameters" Comparison of sea-bed surface sampling results. Confirmation "geoacoustic inversion technique" is correct.
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