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Analysis of Vibration and Acoustic Radiation of Submarine Hull Induced by Longitudinal Vibration of Propulsion Shafting
ZHANG Gan-bo;ZHAO Yao
   2012, 32 (3): 155-158.   DOI: 10.3969/j.issn.1006-1355.2012.03.036
Abstract （1695）            Save
The pulsatile thrust of propeller induced by asymmetrical wake field can cause longitudinal vibration of the propulsion shafting. The vibration will transmit through the shafting, thrust bearing and foundation to the submarine hull, and induce the low frequency underwater acoustic radiation of the hull. Considering the coupled effect of shafting, foundation and the hull, the structural model of the propulsion shafting was established. The propulsion shafting – submarine hull coupled vibration was analyzed, and the acoustic radiation field of the hull was calculated by FEM/BEM based on the mode superposition method. The results show that the longitudinal vibration mode is one of main modes which participates the acoustic radiation. By instilling a dynamic vibration absorber between the thrust bearing and its foundation, the transmission of longitudinal vibration to the hull can be decreased. The acoustic radiation of hull induced by longitudinal vibration of propulsion shafting can be controlled.
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《Wavelet denoising of optimizing threshold based on correlation》
Xiong Jing-qi;Zhao Yao-qiang;Sun Rui;Yang Han-yuan;Deng Yu
   2009, 29 (1): 61-64.   DOI: A
Abstract （2227）            Save
Actual projects are interfered by strong noise, the wavelet transform coefficients of useful signal are always smaller than the noisy wavelet transform coefficients, so the useful signal may be eliminated if we process the coefficients with the same threshold. To solve this problem, threshold optimizing method is brought forward. the weighting array is designed for optimizing the threshold and the weighting is optimized according to the relativity of wavelet coefficients in each decomposing layer so that denoising threshold can be established accurately and useful signal can be kept more integrative. The signal’s antijamming ability can also be enhanced.
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