Conventional f-x empirical mode decomposition（EMD） is an effective random noise attenuation method for use with seismic profiles mainly containing horizontal events.However,when a seismic event is not horizontal,the...Conventional f-x empirical mode decomposition（EMD） is an effective random noise attenuation method for use with seismic profiles mainly containing horizontal events.However,when a seismic event is not horizontal,the use of f-x EMD is harmful to most useful signals.Based on the framework of f-x EMD,this study proposes an improved denoising approach that retrieves lost useful signals by detecting effective signal points in a noise section using local similarity and then designing a weighting operator for retrieving signals.Compared with conventional f-x EMD,f-x predictive filtering,and f-x empirical mode decomposition predictive filtering,the new approach can preserve more useful signals and obtain a relatively cleaner denoised image.Synthetic and field data examples are shown as test performances of the proposed approach,thereby verifying the effectiveness of this method.展开更多
The primary objective of this research problem is to analyze the Rayleigh wave propagation in homogeneous isotropic half space with mass diffusion in Three Phase Lag(TPL)thermoelasticity at two temperature.The governi...The primary objective of this research problem is to analyze the Rayleigh wave propagation in homogeneous isotropic half space with mass diffusion in Three Phase Lag(TPL)thermoelasticity at two temperature.The governing equations of thermodiffusive elastic half space have been solved using the normal mode analysis in order to obtain the Rayleigh wave frequency equation at relevant boundary conditions.The variation of various parameters like non-dimensional speed,attenuation coefficient,penetration depth and specific loss corresponding to thermodiffusion parameter,relaxation time,wave number and frequency has been obtained.The effect of these parameters on Rayleigh wave propagation in thermoelastic half space are graphically demonstrated and variations of all these parameters have been compared within Lord-Shulman(L-S),Green-Nagdhi(GN-III)and Three Phase Lag(TPL)theory of thermoelasticity.展开更多
The conformal transformation solution is presented for the attenuation constant ofTEM transmission lines which can be mapped into the coaxial or the parallel plate lines by certainconformal transformations including t...The conformal transformation solution is presented for the attenuation constant ofTEM transmission lines which can be mapped into the coaxial or the parallel plate lines by certainconformal transformations including the numerical ones.The analytic and numerical results ofsome examples are also given.展开更多
The computational methods of the mode attenuation and group velocity in shallow water are discussed and two novel modified weighted integral formulae are presented. The accuracy of the modified weighted integral formu...The computational methods of the mode attenuation and group velocity in shallow water are discussed and two novel modified weighted integral formulae are presented. The accuracy of the modified weighted integral formulae, cycle distance formulae and weighted integral formulae in the Pekeris channel is compared theoretically and numerically. Transmission losses are calculated by those three kinds of formulae in a shallow water. Theoretical analyses and numerical results show that the modified weighted integral formulae provide higher accuracy than the weighted integral formulae. So the modified weighted integral formulae can be widely used for computing the shallow water acoustic field.展开更多
基金supported by the National Natural Science Foundation of China(No.41274137)the National Engineering Laboratory of Offshore Oil Exploration
文摘Conventional f-x empirical mode decomposition（EMD） is an effective random noise attenuation method for use with seismic profiles mainly containing horizontal events.However,when a seismic event is not horizontal,the use of f-x EMD is harmful to most useful signals.Based on the framework of f-x EMD,this study proposes an improved denoising approach that retrieves lost useful signals by detecting effective signal points in a noise section using local similarity and then designing a weighting operator for retrieving signals.Compared with conventional f-x EMD,f-x predictive filtering,and f-x empirical mode decomposition predictive filtering,the new approach can preserve more useful signals and obtain a relatively cleaner denoised image.Synthetic and field data examples are shown as test performances of the proposed approach,thereby verifying the effectiveness of this method.
文摘The primary objective of this research problem is to analyze the Rayleigh wave propagation in homogeneous isotropic half space with mass diffusion in Three Phase Lag(TPL)thermoelasticity at two temperature.The governing equations of thermodiffusive elastic half space have been solved using the normal mode analysis in order to obtain the Rayleigh wave frequency equation at relevant boundary conditions.The variation of various parameters like non-dimensional speed,attenuation coefficient,penetration depth and specific loss corresponding to thermodiffusion parameter,relaxation time,wave number and frequency has been obtained.The effect of these parameters on Rayleigh wave propagation in thermoelastic half space are graphically demonstrated and variations of all these parameters have been compared within Lord-Shulman(L-S),Green-Nagdhi(GN-III)and Three Phase Lag(TPL)theory of thermoelasticity.
文摘The conformal transformation solution is presented for the attenuation constant ofTEM transmission lines which can be mapped into the coaxial or the parallel plate lines by certainconformal transformations including the numerical ones.The analytic and numerical results ofsome examples are also given.
文摘The computational methods of the mode attenuation and group velocity in shallow water are discussed and two novel modified weighted integral formulae are presented. The accuracy of the modified weighted integral formulae, cycle distance formulae and weighted integral formulae in the Pekeris channel is compared theoretically and numerically. Transmission losses are calculated by those three kinds of formulae in a shallow water. Theoretical analyses and numerical results show that the modified weighted integral formulae provide higher accuracy than the weighted integral formulae. So the modified weighted integral formulae can be widely used for computing the shallow water acoustic field.
