臺灣博碩士論文加值系統

利用資料浮標觀測波浪具有相對的可靠性、耐久性及經濟性，且其不受水深限制，是波浪現場觀測最主要也是最常用的方式。資料浮標可量測得波面水體的垂直加速度變化、波面的傾度變化，經過函數轉換及分析後可得到方向波譜。
本研究之目的係在現行浮標硬體設計架構下改進波浪分析方法，以求得更準確的波浪資訊，包括波高、週期及波向。其中，波高及週期分析誤差最主要的來源是由加速度譜轉換為一維譜時的低頻雜訊干擾，對於此一干擾，本文以一維雜訊譜濾除其干擾，並改良一維雜訊譜的參數選取方法，使其更易於實際作業之應用，且可降低人為的主觀判斷。
另在波向的估算上，資料浮標對波浪之軸不對稱動態反應是造成分析波向誤差的產生原因之一，本研究改良前人修正方向波譜的方法，使其進而能修正資料浮標對波浪之軸不對稱動態反應所造成的相位延遲不一致所產生之主波向誤差。經數值模擬驗證，該方法的確能消減因資料浮標對波浪之軸不對稱動態反應所造成的相位延遲而對主波向估算所造成之影響。
本研究並以上述改良的參數決定方法實際分析花蓮浮標之現場觀測資料，結果證明示性波高、平均週期及尖峰週期發生異常的機率減低16%。而應用改良之主波向估算方法於花蓮現場觀測測資料，顯示是否考慮波浪運動與浮標運動間之振幅響應因子及相位延遲因子，分析所得之主波向的差異介於0~20度之間。

Data buoy, which features comparatively reliability and robustness, is the most frequent applied alternatives on the measurement of oceanographical data. The wave directional spectra can be obtained by analyzing the observed heave, pitch and roll motion of the buoy hull. The accurate determination of the directional spectra serves as a diagnostic tool for the quantification of key mechanisms governing the dynamics of ocean waves. The objective of present study is to improve the accuracy of directional spectra measurement and analysis. New algorithms are intended to be developed instead of modifying current hardware design and mooring structure.
The low frequency noise contaminant, which can be magnified due to the linear conversion from the acceleration spectrum to the displacement spectrum, is the major cause of the inaccuracy. This kind of error leads to mistakenly estimate the significant wave heights and periods. To reduce the error, a correction function to eliminate low-frequency noise is developed based on the previous Lang’s theory. The present method is then proven by numerical simulations and field data analysis to be capable of eliminating the noise. Moreover, the parameters, which should be determined depending on the sea state, is unified to single one in present method. This contributes to improve its applicability of routine analysis.
Concerning to wave directionality analysis, the asymmetric response of amplitudes and phase differences of buoy hull to the waves are the major sources of inaccuracy. This asymmetric response comes from the combined mooring and wind-current effect. On the other hand, the instrumentation of slope measurement will affect the estimation of directional spreading as well. Bi-accelerometers or Gyroscopes, which are available from sensing industry, are widely utilized in the data buoy as inclinometers. However, both the mentioned instrumentations will be effected by the combinations of the two physical mechanisms: the centripetal acceleration from the orbital motion of wave particles and the real inclinations on the wave surface. These two forces apply on the inclinometers with opposite directions and nearly the same order of magnitude and will result in the slope measurement incorrect thus lead to misestimate the main direction and over-estimate the directional spreading. In order to improve the accuracy of directional spreading estimation, Steele's theory was modified and adopted in present study. The newly proposed method was then validated by numerical simulations. Finally, the results demonstrate that the differences of the main direction between the target and the output range from 0 to 20 degree when applying the method to the field wave data.

摘 要 i
Abstract ii
誌 謝 iv
目 錄 v
表 目 錄 vii
圖 目 錄 viii
符 號 說 明 x
第一章 緒論 1
1-1 前言 1
1-2 前人研究 2
1-3 研究動機及目的 4
1-4 本文組織 5
第二章 資料浮標測波原理及其影響因素 6
2-1 資料浮標測波系統 6
2-2 浮標測波原理 7
2-3 影響浮標測波的因素 12
第三章 波高週期估算的改進 18
3-1 一維譜的雜訊及其對波高週期的影響 18
3-2低頻雜訊修正 20
3-2.1 低頻雜訊濾除經驗公式 20
3-2.2 雜訊修正因子的決定方法及其影響 21
3-3 雜訊修正因子決定方法之改良 22
3-4現場實測資料分析 23
3-4.1 截斷頻率與相關係數的關係 23
3-4.2 低頻雜訊公式改良前後對分析結果的差異 24
第四章 波向修正 39
4.1波向誤差 39
4.2波向誤差修正方法 40
4.3利用模擬資料探討相位延遲對主波向的影響 45
4.4分析實測資料探討修正前後主波向之差異 47
第五章 結論與建議 52
結論 52
建議 53
參考文獻 54

1.王維紀(1984)”浮標測波資料處理之評介”，海象分析與預報研討會論文集。
2.李春明(1993)，”海洋方向波譜的觀測與分析”，國立成功大學碩士論文。
3.俞聿修(1992) “隨機波浪及其工程運用”，大連理工大學出版社。
4.郭一羽(2001)，”海岸工程學”，文山書局。
5.陳嘉元、黃明志、徐仕昇、連永順(1996)，”Butterworth 低通濾波器在降低資料浮標低頻雜訊之應用”，海洋工程研討會論文集。
6.陳嘉元、黃明志、徐仕昇、連永順(1997)，”加速度計對資料浮標測波性能之影響”，海洋工程研討會論文集。
7.董東璟，莊士賢，高家俊(1997)”海氣象觀測資料品管系統之建立”，海洋工程研討會論文集。
8.黃明志(1998)，”浮標測波低頻雜訊修正函數決定方法”，海洋工程研討會論文集。
9.鄧中柱(1991) “浮標系統與工程”，資料浮標研討會論文集。
10.鄧中柱(1994) “作業化資料浮標之評介”，海象預報與分析研討會論文集。
11.Allender, J., Audunson, T. “The WADIC project: a comprehensive field evaluation of directional wave instrumentation”, Ocean Engineering, Vol.16, pp.505~536, 1989
12.Benoit M. & Teisson C., “Laboratory comparison of directional wave measurement systems and analysis techniques”, Proc. 25th Int. Conf. On Coastal Eng.(ASCE), pp 42-56, 1994.
13.E. B. Carpenter, J. W. Leonard and S. C. S. Yim “Experimental and numerical investigations of tethered spar and sphere buoys in irregular waves”, Ocean Engineering, Vol.22, pp.765~784, 1995.
14.Earle, M. D. and K. A. Bush (1982) “Strapped-down accelerometer effects on NDBO wave measurements”, Proc. IEEE Conference of Oceans’82, pp. 838-843. Washington, D.C., U.S.A.
15.Earle, M. D. and K. E. Steele, and Y.H.L. Hsu (1984) “Wave spectral corrections for measurements with hull-fixed accelerometers”, Proc. IEEE Conference of Oceans’82, pp. 838-843. Washington, D.C., U.S.A.
16.Huang Min-Chih and Jia-Yuan Chen (1998) “Wave direction analysis from data buoys”, Ocean Engng, Vol. 25, No. 8, pp. 621-637.
17.Isobe, M., K. Kondo and K. Horikawa, “Extension of MLM for Estimating Directional Wave Spectrum”, Proc. Sympo. On Description and Modeling of Directional Seas, Paper No.A-6, 1984.
18.Kenneth E. Steele. Joseph Chi-Kin Lau, and Yuan-Huang L. Hsu “Theory and application of calibration techniques for an NDBC directional wave measurements buoy”, IEEE journal of oceanic engineering. Vol. OE-10, NO. 4, October 1985.
19.Lang, Norman “The empirical determination of a noise function for NDBC buoys with strapped-down accelerometers”, Proc. IEEE Conference of Oceans’87, pp. 225-228. Halifax, NS Canada.
20.Longuet-Higgins, M.S., Cartwright, D.E. & Smith, N.D. “Observations of the directional spectrum of sea wave using the motions of a floating buoy”, Proc. Conf. Ocean Wave Spectra, Prentice-Hall Inc., pp.11~132,1963
21.M. J. Tucker (1989) “Interpreting directional data from large Pitch-roll-heave buoys”, Ocean Engng, Vol. 16, No 2, pp. 173-192.
22.Steele, K. E., Chung-Chu Teng and D. W. Wang (1992) “Wave direction Measurements using pitch-roll buoys”, Ocean Engng, Vol. 19, No 4, pp. 349-375.