Passive seismic data contain large amounts of low-frequency information. To effectively extract and compensate active seismic data that lack low frequencies, we propose a multitaper spectral reconstruction method base...Passive seismic data contain large amounts of low-frequency information. To effectively extract and compensate active seismic data that lack low frequencies, we propose a multitaper spectral reconstruction method based on multiple sinusoidal tapers and derive equations for multisource and multitrace conditions. Compared to conventional cross correlation and deconvolution reconstruction methods, the proposed method can more accurately reconstruct the relative amplitude of recordings. Multidomain iterative denoising improves the SNR of retrieved data. By analyzing the spectral characteristics of passive data before and after reconstruction, we found that the data are expressed more clearly after reconstruction and denoising. To compensate for the low-frequency information in active data using passive seismic data, we match the power spectrum, supplement it, and then smooth it in the frequency domain. Finally, we use numerical simulation to verify the proposed method and conduct prestack depth migration using data after low-frequency compensation. The proposed power-matching method adds the losing low frequency information in the active seismic data using the low-frequency information of passive- source seismic data. The imaging of compensated data gives a more detailed information of deep structures.展开更多
A new kind of single-polarization photonic crystal fiber(PCF) is proposed.Two kinds of multi-component glasses and the air are selected as working materials.Through using the full vector finite element method(FEM) and...A new kind of single-polarization photonic crystal fiber(PCF) is proposed.Two kinds of multi-component glasses and the air are selected as working materials.Through using the full vector finite element method(FEM) and the perfectly matched layers(PML),the polarization-maintaining characteristic and the confinement loss of the fiber are analyzed,respectively.In addition,the single-polarization region of the fiber around 1.55 ìm is discussed.Numerical simulations show that the fiber maintains single-polarization operation within the wavelength range of 1.421-1.696μm.The birefringence can reach 6.988×10-3,and the confinement loss is as low as 0.012 dB/m when 7 layers of ring holes are arranged in the cladding at λ=1.55μm.展开更多
基金sponsored by the Natural Science Foundation of China(No.41374115)National High Technology Research and Development Program of China(863 project)(No.2014AA06A605)
文摘Passive seismic data contain large amounts of low-frequency information. To effectively extract and compensate active seismic data that lack low frequencies, we propose a multitaper spectral reconstruction method based on multiple sinusoidal tapers and derive equations for multisource and multitrace conditions. Compared to conventional cross correlation and deconvolution reconstruction methods, the proposed method can more accurately reconstruct the relative amplitude of recordings. Multidomain iterative denoising improves the SNR of retrieved data. By analyzing the spectral characteristics of passive data before and after reconstruction, we found that the data are expressed more clearly after reconstruction and denoising. To compensate for the low-frequency information in active data using passive seismic data, we match the power spectrum, supplement it, and then smooth it in the frequency domain. Finally, we use numerical simulation to verify the proposed method and conduct prestack depth migration using data after low-frequency compensation. The proposed power-matching method adds the losing low frequency information in the active seismic data using the low-frequency information of passive- source seismic data. The imaging of compensated data gives a more detailed information of deep structures.
基金supported by the Basic Research Foundation of Harbin Engineering Universitythe Special Foundation for Harbin Young Scientists (No. 2008RFQXG031)
文摘A new kind of single-polarization photonic crystal fiber(PCF) is proposed.Two kinds of multi-component glasses and the air are selected as working materials.Through using the full vector finite element method(FEM) and the perfectly matched layers(PML),the polarization-maintaining characteristic and the confinement loss of the fiber are analyzed,respectively.In addition,the single-polarization region of the fiber around 1.55 ìm is discussed.Numerical simulations show that the fiber maintains single-polarization operation within the wavelength range of 1.421-1.696μm.The birefringence can reach 6.988×10-3,and the confinement loss is as low as 0.012 dB/m when 7 layers of ring holes are arranged in the cladding at λ=1.55μm.
