臺灣博碩士論文加值系統

本文係探討以活塞式造波機水槽模擬近岸環境噪音，使用水下麥克風收集聲音訊號來分析碎波氣泡，並以數位攝影機拍攝氣泡影像以作為觀察。所使用的水槽設置於國立中山大學海洋科學院，水槽尺寸為長35公尺、寬1公尺、高1.2公尺，海床坡度為1：5，並以波高、週期及水深作為實驗變數，來探討碎波氣泡產生的環境噪音。本文用短時傅立葉轉換取得氣泡的聲音頻譜圖，並且使用MATLAB程式計算平均聲壓值與氣泡數。氣泡的定義為在頻譜圖中響應頻率範圍由0.5至10 kHz之間的峰值，因此，由碎波產生的氣泡可由能量分佈來推算。結果發現，噪音的聲壓值與波高、週期的相關性係數均高達0.7，同時，將本文得到的相關結果與實海量得的環境噪音比較。

This article studies ambient noise in the surf zone that was simulated by piston-type wavemaker in the tank. The experiment analyzed the bubbles of breaking wave by using a hydrophone to receive the acoustic signal, and the images of bubbles were recorded by a digital video camera to observe distribution of bubbles. The tank is in College of Marine Sciences, National Sun Yat-sen University, the dimensions of water tank are 35 m ×1 m ×1.2 m, and the slope of the simulated seabed is 1:5. The studied parameters of ambient noise generates by breaking wave bubbles were wave height, period, and water depth. Short-time Fourier Transform was applied to obtain the acoustic spectrum of bubbles, MATLAB programs were used to calculate mean sound pressure level, and determine number of bubbles. Bubbles with resonant frequency from 0.5 to 10 kHz were studied, counted from peaks in the spectrum. The number of bubbles generated by breaking waves could be estimated by bubbles energy distributions. The sound pressure level of ambient noise was highly related to the wave height and period, with correlation coefficient 0.7. The results were compared with other studies of ambient noise in the surf.

摘要…………………………………………………………i
Abstract…………………………………………………………ii
目錄…………………………………………………………iii
圖目錄…………………………………………………………vii
表目錄…………………………………………………………x
第一章 緒論………………………………………………1
1.1 研究背景………………………………………………1
1.2 相關文獻………………………………………………2
1.3 研究目的………………………………………………5
1.4 本文架構………………………………………………5
第二章 理論介紹………………………………………………6
2.1 碎波與海洋環境噪音…………………………………6
2.1.1 深海的碎波……………………………………………6
2.1.2 淺海的碎波……………………………………………7
2.2 氣泡與海洋環境噪音…………………………………9
2.3 氣泡共振………………………………………………11
2.3.1 氣泡運動方程式…………………………………11
2.3.2 阻尼效應………………………………………………14
2.3.3 共振的方式……………………………………………16
2.4 傅立葉轉換……………………………………………18
2.4.1 快速傅立葉轉換…………………………………18
2.4.2 短時傅立葉轉換…………………………………19
第三章 實驗架構與方法…………………………………21
3.1 實驗架構………………………………………………21
3.1.1 實驗設備………………………………………………21
3.1.2 實驗架設………………………………………………22
3.2 實驗方法………………………………………………24
3.2.1 造波過程………………………………………………24
3.2.2 氣泡拍攝………………………………………………24
3.2.3 收錄氣泡的聲音………………………………… 26
3.3 實驗分析……………………………………………… 26
3.3.1 實驗項目………………………………………………26
3.3.2 聲學分析………………………………………………27
3.3.3 氣泡計算程式架構…………………………………28
第四章 結果與討論……………………………………………… 30
4.1 雜訊分析……………………………………………… 30
4.1.1 儀器雜訊噪音…………………………………………30
4.1.2 背景噪音………………………………………………32
4.2 碎波噪音……………………………………………… 33
4.3 氣泡訊號……………………………………………… 34
4.3.1 氣泡訊號的特性………………………………… 34
4.3.2 氣泡共振頻率與半徑…………………………………35
4.3.3 氣泡能量分佈……………………………………………36
4.4 波浪與噪音………………………………………………39
4.4.1 波高對噪音的影響…………………………………39
4.4.2 週期對噪音的影響…………………………………42
4.5 碎波相似參數與噪音…………………………………43
4.6 實海與水槽實驗差異…………………………………45
4.6.1 阻尼效應差異………………………………………………45
4.6.2 實驗環境差異………………………………………………46
4.7 氣泡影像……………………………………………… 46
第五章 結論與建議………………………………………………48
5.1 結論…………………………………………………………48
5.2 建議…………………………………………………………49
參考文獻……………………………………………………………50
附錄A………………………………………………………………53
附錄A1………………………………………………………………63
附錄A2………………………………………………………………65
附錄B………………………………………………………………67
附錄C………………………………………………………………69
附錄D………………………………………………………………71
附錄E………………………………………………………………75
附錄F………………………………………………………………81
附錄G………………………………………………………………83

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