臺灣博碩士論文加值系統

噪音控制分為被動式及主動式兩種。而本文提出ㄧ種新的作法於主動管道噪音控制中，即是利用壓電片給予管道管壁一振動之激振力，藉由管壁振動使管道產生一與主要噪音聲源反向之聲波，進而達到下游聲壓衰減之目的。此作法不需要再準備第二聲源所需之設備(例如揚聲器或平板)，僅需利用本身管道系統和壓電片，大大地節省了器材成本及設備所須的配置空間。

本文中，利用FIR(Finite Impluse Response)數位濾波器作為系統控制之主體架構並直接以訊號產生器產生之單頻或雙頻訊號作為控制之參考輸入，再利用LMS(Least Mean Square)演算法來即時修正濾波器之係數，以期能達到最佳的控制效果。 另外，會再分析由於無限長圓柱殼體振動所造成之聲輻射。

在結果方面，本實驗於各管聲幅射能力較佳之單頻率進行主動聲場控制時，皆能約有40dB左右之音壓衰減量；而對於各管聲幅射能力較佳之雙頻率進行主動聲場控制時，皆能有15~35dB左右之不錯的音壓衰減量，可見此方法之可行性。但當激振力為管道聲幅射能力較差之頻率時，則主動聲場控制的效果不佳。在最後的章節將會對其控制的效果作ㄧ探討，並加以討論。

There are two techniques in noise control,which are passive and active noise control.This thesis is to provide another approach to active noise control(ANC).It is to use a piezoelectric transducer(PZT) to excite the duct wall.The wall-vibration induced feedback sound wave can combine with primary noise to reduce the downstream sound pressure.Accordingly,only a duct and a piezoelectric tr-
ansducer are wanted in this approach.Thus the cost and the space required for the apparatus to be wanted are saved much more.
In experiment,we use a FIR digital filter as the main structure of the control system and meanwhile take a single-frequency or a dual-frequency signal as the reference input directly produced by a function generator.Weighting coefficients of the digital filter are adjusted by using LMS algorithm in order to achieve the best performance.Besides,the sound radiation by vibrating an infinite cylindrical shell will be analyzed.
The result of this study shows great attenuation of downstream sound pressure level by about 40 dB will be obtained at some frequencies.Similar situation occurs for dual frequencies at which greater radiation from duct wall exists,the attenuation of downstream sound pressure levels by about 15~35dB is obtained.The actuality as discussed can demonstrate it is feasible to use wall-vibration induced source to adaptively active control on the sound transmissi-
on in a circular duct.

摘要……………………………………………………………………….Ⅰ
ABSTRACT………………………………………………………………Ⅱ
目錄………………………………………………………………………Ⅲ
圖目錄……………………………………………………………………Ⅴ
表目錄……………………………………………………………………Ⅸ

第一章 緒論

1-1 前言……………………………………………………………1
1-2 文獻回顧……………………………………………………..5
1-3 研究方向與步驟…………………………………………….7

第二章 主動控制理論

2-1 連續訊號之取樣..…………………………………………..9
2-2 數位濾波器之理論………………………………………..12
2-3 LMS演算法…………………………………………………17

第三章 管道聲場

3-1 管道聲場結構………………………………………………23
3-2 管道消音機制………………………………………………28

第四章 管壁振動之聲場

4-1 壓電材料的基本性質……………………………………..30
4-2 無限長圓柱殼體的聲輻射分析………………………….31
4-2-1 薄圓柱殼的運動方程……………………………..31
4-2-2 圓柱殼體對內部聲場之作用…………………….34
4-2-3 圓柱殼體對外部聲場之作用…………………….37
4-2-4 激振力對圓柱殼體之作用……………………....39
4-2-5 聲輻射之求解………………………………………40
第五章 系統實驗架構

5-1 實驗設備…………………………………………………….42
5-2 實驗架構…………………………………………………….46
5-3 實驗過程與背景考量……………………..………………48
5-4 噪音消除之最佳化觀點…………………………………..50

第六章 實驗結果與分析討論

6-1 聲壓位準曲線………………………………………………51
6-2 實驗數據…………………………………………………….54
6-3 實驗結果討論…………………………………………….103

第七章 結論與未來研究方向

7-1 結論……………………..…………………………………106
7-2 未來研究方向…………………………………………….107

參考文獻………………………………………………………………108

1. P.Lueg, “Process of Silencing Sound Oscillation,” U.S. Patent No.2,043,416, 1936.

2. M. Jessel and G. A. Mangiante, “Active Sound Absorbers in an Air Duct,” Journal of Sound and Vibration, Vol. 23(3), pp. 383-390, 1972.

3. M.A. Swinbanks, “Active Control of Sound Propagation in Long Ducts,” Journal of Sound and Vibration, Vol. 27(3), pp. 411-436, 1973.

4. J. H. B. Pools and H. G. Leventhall, “An Experimental Study of Swinbanks‘ Method of Active Attenuation of Sound In Ducts,” Journal of Sound and Vibration, Vol. 49, pp. 257-266, 1976.

5. M. Berengier and A. Roure, “Broadband Active Sound Absorption in a Duct Carrying Uniformly Flowing Fluid,” Journal of Sound and Vibration, Vol. 68, pp. 437-449, 1980.

6. K h. Eghtesadi and H. G. Leventhall, “Active Attenuation of Noise: the Chelsea Dipole,” Journal of Sound and Vibration, Vol. 75, 1981.


7. K h. Eghtesadi and H. G. Leventhall, “The Tight-coupled Monopole Active Attenuator in a Duct,” Noise Control Engineering, Vol. 20(2), pp. 16-20, 1983.

8. C. Burgess, “Active Adaptive Sound Control in a duct : A Comupter Simulation,” Journal of the Acoustical Society of America, Vol. 70, pp.715-726, September 1981.

9. C.F. Ross, “An Algorithm For Designing A Broadband Active Sound Control System,” Journal of Sound and Vibration, Vol. 80, pp.373-380, 1982.

10. S.J. Elliott, I.M. Stothers and P.A. Nelson, “ A Multiple Error LMS Algoruthm and Its Application to the Active Control of Sound and Vibration ,” IEEE Transactions on Acoustics, Speech and Signal Processing, Vol. 35(4), April 1987.

11. L.J. Eriksson and M.C. Allie, “Use of Random Noise for On-line Transducer Modeling in an Adaptive Active Attenuation System,” Journal of the Acoustical Society of Amercia, Vol. 85(2), pp.797-802, February 1989.

12. William D. Stanley,Gary R. Dougherty, Ray Dougnerty. Digital Signal Processing . Prentice-Hall Infernation Editions. 1991.

13. B. Widrow and S. D. Stearns. Adaptive Signal Processing. Prentice Hall. New Jersey. 1985.

14. P. A. Nelson and S. J. Elliott. Active Control Of Sound. Academic Press. New York. 1992.

15. C. F. N. Cowan and P. M. Grant. Adapative Filters. Prentice Hall. New Jersey. 1985.

16. S. Haykin. Adapative Filter Theory. Prentice Hall. New Jersey. 1991.

17. P.M.Morse and K.U.Ingard. Theoretical Acoustics. McGraw-
Hill. New York. 1968.

18. 劉雲輝，圓形管道聲場之適應性主動控制研究，國立台灣大學造船工程學系，博士學位論文，民國85年。

19. Courtney B. Burroughs,”Acoustic radiation from fluid-loaded infinite circular cylinders with doubly periodic ring supports,” Journal of the Acoustical Society of Amercia, Vol. 75(3), pp.715-722, March 1984.




20. Chen Jun-ming,Huang Yu-ying and Zeng Ge-wei,”Vibration and acoustic radiation from orthogonally stiffened infinite circular cylindrical shells in water,” China Ocean Engineering,Vol.16(4),
pp.437-452,2002.

21.E.A.Skelton and J.H.James.Theorectical acoustic of underwater structures. London:Imperial College Press,pp.241-281,1997.

22.研華，PCI1712 User''s manual.

23. J. D. Stell and R. J. Bernhard, “Active Control of Sound in Acoustic Wave guides, Part I: Theory,” Journal of Sound and Vibration, Vol. 173(2), pp. 179-196, 1994.

24. J. D. Stell and R. J. Bernhard, “Active Control of Sound in Acoustic Wave guides, Part II: Considerations For Implementation in Ducts,” Journal of Sound and Vibration, Vol. 173(2), pp. 197-215, 1994.