A matching pursuit method based on training an over-complete dictionary is investigated.By using the K-singular value decomposition(K-SVD)algorithm,an over-complete dictionary that describes the Lamb wave signals is t...A matching pursuit method based on training an over-complete dictionary is investigated.By using the K-singular value decomposition(K-SVD)algorithm,an over-complete dictionary that describes the Lamb wave signals is trained.The results demonstrate that the method can effectively remove redundant information and separate multiple Lamb wave modes.The matching pursuit method with the K-SVD algorithm shows its efficiency for Lamb wave signal processing.展开更多
An analytical model of Lamb wave scattering from a circular blind hole in isotropic plates is presented using the Mindlin plate theory for describing in-plane and flexural wave modes simultaneously. The model makes us...An analytical model of Lamb wave scattering from a circular blind hole in isotropic plates is presented using the Mindlin plate theory for describing in-plane and flexural wave modes simultaneously. The model makes use of the wave function expansion technique and the boundary conditions at the hole edge to evaluate the scattered far fields of three fundamental guided wave modes. Comparisons are made to existing approximate models using Poisson/Kirchhoff theory and Poisson/Mindlin theory and a 3D model using the exact 3D equations. The results reveal that the present model is more consistent with the exact 3D model at higher frequencies than existing approximate models.展开更多
We present a theoretical investigation of the scattering of high frequency S0 Lamb mode from a circular blind hole defect in a plate based on the 3D theory. The SO wave is incident at the frequency above the A1 mode c...We present a theoretical investigation of the scattering of high frequency S0 Lamb mode from a circular blind hole defect in a plate based on the 3D theory. The SO wave is incident at the frequency above the A1 mode cut-off frequency, in which the popular approximate plate theories are inapplicable. Due to the non-symmetric blind hole defect, the scattered fields will contain higher order converted modes in addition to the fundamental SO and AO modes. The far-field scattering amplitudes of various propagating Lamb modes for different hole sizes are inspected. The results are compared with those of lower frequencies and some different phenomena are found. Two-dimensional Fourier transform （2DFT） results of transient scattered Lamb and SH wave signals agree well with the analytical dispersion curves, which check the validity of the solutions from another point of view.展开更多
基金Supported by the National Natural Science Foundation of China under Grant Nos 11074164,11274226,11074273,61171145the Innovation Foundation of Shanghai Municipal Commission of Education(No 11YZ17)the Ph.D.Foundation of Ministry of Education of China(20103108120011)。
文摘A matching pursuit method based on training an over-complete dictionary is investigated.By using the K-singular value decomposition(K-SVD)algorithm,an over-complete dictionary that describes the Lamb wave signals is trained.The results demonstrate that the method can effectively remove redundant information and separate multiple Lamb wave modes.The matching pursuit method with the K-SVD algorithm shows its efficiency for Lamb wave signal processing.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11274226, 11074164 and 61171145.
文摘An analytical model of Lamb wave scattering from a circular blind hole in isotropic plates is presented using the Mindlin plate theory for describing in-plane and flexural wave modes simultaneously. The model makes use of the wave function expansion technique and the boundary conditions at the hole edge to evaluate the scattered far fields of three fundamental guided wave modes. Comparisons are made to existing approximate models using Poisson/Kirchhoff theory and Poisson/Mindlin theory and a 3D model using the exact 3D equations. The results reveal that the present model is more consistent with the exact 3D model at higher frequencies than existing approximate models.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11474195,11274226 and 61171145
文摘We present a theoretical investigation of the scattering of high frequency S0 Lamb mode from a circular blind hole defect in a plate based on the 3D theory. The SO wave is incident at the frequency above the A1 mode cut-off frequency, in which the popular approximate plate theories are inapplicable. Due to the non-symmetric blind hole defect, the scattered fields will contain higher order converted modes in addition to the fundamental SO and AO modes. The far-field scattering amplitudes of various propagating Lamb modes for different hole sizes are inspected. The results are compared with those of lower frequencies and some different phenomena are found. Two-dimensional Fourier transform （2DFT） results of transient scattered Lamb and SH wave signals agree well with the analytical dispersion curves, which check the validity of the solutions from another point of view.
