A novel tunable-quality-factor （tunable-Q） contourlet transform for geometric image representation is proposed. The Laplacian pyramid in original contourlet decomposes a signal into channels that have the same bandw...A novel tunable-quality-factor （tunable-Q） contourlet transform for geometric image representation is proposed. The Laplacian pyramid in original contourlet decomposes a signal into channels that have the same bandwidth on a logarithmic scale, and is not suitable for images with different behavior in frequency domain. We employ a new tunable-Q decomposition defined in the frequency domain by which one can flexibly tune the bandwidth of decomposition channels. With an acceptable redundancy, this tunable-Q contourlet is also anti-aliasing and its basis is sharply localized in the desired area of frequency and spatial domain. Our experiments in nonlinear approximation and denoising show that the contourlet using a better-suitable quality factor can achieve a more promising performance and often outperform wavelets and the previous contourlets both in visual quality and in terms of peak signal-to-noise ratio.展开更多
The multiscale finite element method(MsFEM)combined with conventional finite element method(CFEM)is proposed to solve static magnetic field in the ribbon magnetic core with non-periodical corners considered.Firstly,a ...The multiscale finite element method(MsFEM)combined with conventional finite element method(CFEM)is proposed to solve static magnetic field in the ribbon magnetic core with non-periodical corners considered.Firstly,a simple 2-dimensional electrostatic problem is used to introduce the MsFEM implementation process.The results are compared to analytical method,as well as conventional FEM.Then,an exam-ple of magneto-static problem is considered for a ribbon magnetic core built sheet by sheet as well as corners taken into considera-tion.Conventional FEM and MsFEM are used to compute the magneto-static field by adopting scalar magnetic potential.Both magnetic potential and magnetic flux density on a certain path are compared.It is shown that the results obtained by MsFEM agree well with the one from conventional FEM.Moreover,MsFEM combined with FEM is potentially a general strategy for mul-tiscale modeling of ribbon magnetic cores with complex and non-periodical structures considered,like corners and T-joints,which can effectively reduce the computational cost.展开更多
基金supported by the National Natural Science Foundation of China(4097117341071188)
文摘A novel tunable-quality-factor （tunable-Q） contourlet transform for geometric image representation is proposed. The Laplacian pyramid in original contourlet decomposes a signal into channels that have the same bandwidth on a logarithmic scale, and is not suitable for images with different behavior in frequency domain. We employ a new tunable-Q decomposition defined in the frequency domain by which one can flexibly tune the bandwidth of decomposition channels. With an acceptable redundancy, this tunable-Q contourlet is also anti-aliasing and its basis is sharply localized in the desired area of frequency and spatial domain. Our experiments in nonlinear approximation and denoising show that the contourlet using a better-suitable quality factor can achieve a more promising performance and often outperform wavelets and the previous contourlets both in visual quality and in terms of peak signal-to-noise ratio.
文摘The multiscale finite element method(MsFEM)combined with conventional finite element method(CFEM)is proposed to solve static magnetic field in the ribbon magnetic core with non-periodical corners considered.Firstly,a simple 2-dimensional electrostatic problem is used to introduce the MsFEM implementation process.The results are compared to analytical method,as well as conventional FEM.Then,an exam-ple of magneto-static problem is considered for a ribbon magnetic core built sheet by sheet as well as corners taken into considera-tion.Conventional FEM and MsFEM are used to compute the magneto-static field by adopting scalar magnetic potential.Both magnetic potential and magnetic flux density on a certain path are compared.It is shown that the results obtained by MsFEM agree well with the one from conventional FEM.Moreover,MsFEM combined with FEM is potentially a general strategy for mul-tiscale modeling of ribbon magnetic cores with complex and non-periodical structures considered,like corners and T-joints,which can effectively reduce the computational cost.
