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A Wave Superposition-Finite Element Method for Calculating the Radiated Noise Generated by Volumetric Targets in Shallow Water
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作者 TANG Yu-hang ZHAO Zhe +3 位作者 LI Hai-chao PANG Fu-zhen TANG Yang DU Yuan 《China Ocean Engineering》 SCIE EI CSCD 2024年第5期845-854,共10页
A combined method of wave superposition and finite element is proposed to solve the radiation noise of targets in shallow sea.Taking the sound propagation of spherical sound source in shallow sea as an example,the rad... A combined method of wave superposition and finite element is proposed to solve the radiation noise of targets in shallow sea.Taking the sound propagation of spherical sound source in shallow sea as an example,the radiation sound field of the spherical sound source is equivalent to the linear superposition of the radiation sound field of several internal point sound sources,and then the radiated noise induced by spherical sound source can be predicted quickly.The accuracy and efficiency of the method are verified by comparing with the numerical results of finite element method,and the rapid prediction of underwater radiated noise of cylindrical shell is carried out based on the method.The results show that compared with the finite element method,the relative error of the calculation results under different simulation conditions does not exceed 0.1%,and the calculation time is about 1/10 of the finite element method,so this method can be used to solve the radiated noise of shallow underwater targets. 展开更多
关键词 shallow water radiation noise wave superposition principle cylindrical shell finite element
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Stream Function Wave Derived by Unified Variational Principle of Water Gravity Wave
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作者 Fu Yuhua Senior Engineer, China Offshore Oil Production Research Center, P.O.Box 9607, Beijing, 100086 《China Ocean Engineering》 SCIE EI 1997年第2期187-200,共14页
Based on the linear wave, solitary wave and fifth order stokes wave derived by use of the Unified Variational Principle of Water Gravity Wave (UVPWGW), this paper derives stream function wave theory by using UVPWGW. T... Based on the linear wave, solitary wave and fifth order stokes wave derived by use of the Unified Variational Principle of Water Gravity Wave (UVPWGW), this paper derives stream function wave theory by using UVPWGW. This paper will handle the Kinematic Free Surface Boundary Condition (KFSBC) and Dynamic Free Surface Boundary Condition (DFSBC) directly and give the optimum solution, instead of the conditions Sigma(Q(av) - Q(i))(2) = min, and the related equations of stational condition. When the wave height H, period T and water depth D are given, the original stream function wave will be determined, and can not be adjusted if it does not agree with the real case; in the present method, the adjustment can be done by adding several constraint conditions, for example, the wave profile can be adjusted according to the condition of accurate peak position. The examples given in this paper show that for the original stream function wave, the DFSBC can be fairly well satisfied, but the KFSBC can not; however, the stream function wave derived by UVPWGW is better than the original one in the sense of minimum error squares in the aspect of the level at which KFSBC and DFSBC are satisfied. 展开更多
关键词 unified variational principle of water gravity wave stream function wave theory optimum solution
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A variational principle analysis of surface acoustic waves propagating under periodic metal grating with finite thickness 被引量:1
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作者 XU Fangqian ZHANG Yanhua 《Chinese Journal of Acoustics》 2013年第3期264-273,共10页
A theoretical method is presented,which analyzes properties of surface acoustic waves propagating on metallic gratings with finite thickness by combining finite element method with variational principle on surface aco... A theoretical method is presented,which analyzes properties of surface acoustic waves propagating on metallic gratings with finite thickness by combining finite element method with variational principle on surface acoustic waves propagating on periodic metal gratings. Based on D.P.Chen and Haus theory,a finite element method is used to investigate the effects of metallic gratings upon the propagation of surface acoustic waves.The coupling-of-modes parameters contributed by mechanical loading are expressed by the matrix derived from the finite element method.Consequently D.P.Chen and Haus theory can also be applied to analyze the properties of surface acoustic waves propagating on metallic gratings with finite thickness and arbitrary shape.Finally,the characteristics of surface acoustic waves propagating under gold and aluminum or silver gratings on a few piezoelectric crystals are studied.Numerical results of the coupling-of-modes parameters of the surface acoustic waves are obtained. 展开更多
关键词 A variational principle analysis of surface acoustic waves propagating under periodic metal grating with finite thickness
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Migration of Magnetotelluric Data in Two——Dimensional Model
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作者 Wei Sheng Wang JiayingChina University of Geosciences , Wuhan 430074 《Journal of Earth Science》 SCIE CAS CSCD 1991年第1期105-113,共9页
Since the wave equation of magnetoteiluric (MT)field is similar to the one of seismic , the migration techniques used in seismic can be applied to MT data . In this paper we make use of the principle of reflector mapp... Since the wave equation of magnetoteiluric (MT)field is similar to the one of seismic , the migration techniques used in seismic can be applied to MT data . In this paper we make use of the principle of reflector mapping (i. e. U/D imaging principle ) to image MT data . That is, the MT wavefield observed on the surface of the earth can be resolved into upgoing and downgoing waves , the waves are extrapolated downward by the phase - shift method or the phase - shift plus interpolation (PSPI )method . Conductivity interfaces of the medium could be found by using the time coincidence of the upgoing and downgoing waves . Theoretical calculations show that the migration technique of MT data presented here is very effective . It can not only enhance the lateral resolution of MT data , but also obtain the visual image of subsurface interfaces . As compared with the conventional 2 - D inversion , this procedure is more simple in calculation and can be easily put into practice on a personal computer and is able to obtain the MT depth section , which is similar to seismic section . 展开更多
关键词 migration imaging upgoing/downgoing waves the principle of reflec- tor mapping phase-shift method phase-shift plus interpolation method depth section.
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