The spatial autocorrelation(SPAC)(also known as the Aki’s spectral method)of ambient seismic noise has been widely adopted in surface wave phase velocity extraction.In two-dimensional cases,the surface wave velocity ...The spatial autocorrelation(SPAC)(also known as the Aki’s spectral method)of ambient seismic noise has been widely adopted in surface wave phase velocity extraction.In two-dimensional cases,the surface wave velocity can be calculated by fitting the SPAC coefficients with the zero-order Bessel function of the first kind or using the zeros of the Aki’s spectrum.This method has also been extended to active-source records.This study examined the application of the zeros of Aki’s spectra on active-source records using theoretical analysis and numerical simulation.We show that the zeros of the Aki’s spectrum should be associated with the zeros of the cosine function instead of the zeros of the zero-order Bessel function when extracting the phase velocity of the surface wave,considering the data acquisition and processing of the active-source records.The proposed method was then applied to the active-source data from methane explosion experiments collected using a dense array in Tongzhou,the subcenter of Beijing,for extracting the phase velocity of Rayleigh wave.The extracted dispersion curves were integrated with those obtained by beamforming the ambient noise to yield broadband dispersion curves at 0.3–6 Hz.This provides insightful results at high frequencies,at which less information can be obtained through the passive-source beamforming.The combing phase velocities from active-source with those obtained from ambient noise provide a better constrain on the shallow structure.Based on the combined fundamental mode dispersion curves at 28 excitation points,the S-wave velocity structure below the dense array is obtained by depth inversion.Due to the constraints imposed by the high-frequency information from active source,the estimated vS30 are more reliable and can be used to the site classification.展开更多
Dear Editor,Heart failure(HF)is a common multi-faceted and life-threatening syndrome,of which up to 23%occur acute kidney injury(AKI)[1].HF-related AKI is largely overlooked or delayed in identification[2].Approximate...Dear Editor,Heart failure(HF)is a common multi-faceted and life-threatening syndrome,of which up to 23%occur acute kidney injury(AKI)[1].HF-related AKI is largely overlooked or delayed in identification[2].Approximately 85%of AKI cases that occurred during cardiac hospitalization in China were either ignored or identifi ed too late[3].Currently,there are no specific guidelines for the management of HF-related AKI.Hence,it is essential to identify patients at the risk of developing AKI and intervene promptly.展开更多
基金supported by the National Natural Science Foundation of China(No.42474081)the Fundamental Research Funds from the Institute of Geophysics,China Earthquake Administration(No.DQJB 23K34)the Science and Technology Department of Henan Province of China(No.242102320039).
文摘The spatial autocorrelation(SPAC)(also known as the Aki’s spectral method)of ambient seismic noise has been widely adopted in surface wave phase velocity extraction.In two-dimensional cases,the surface wave velocity can be calculated by fitting the SPAC coefficients with the zero-order Bessel function of the first kind or using the zeros of the Aki’s spectrum.This method has also been extended to active-source records.This study examined the application of the zeros of Aki’s spectra on active-source records using theoretical analysis and numerical simulation.We show that the zeros of the Aki’s spectrum should be associated with the zeros of the cosine function instead of the zeros of the zero-order Bessel function when extracting the phase velocity of the surface wave,considering the data acquisition and processing of the active-source records.The proposed method was then applied to the active-source data from methane explosion experiments collected using a dense array in Tongzhou,the subcenter of Beijing,for extracting the phase velocity of Rayleigh wave.The extracted dispersion curves were integrated with those obtained by beamforming the ambient noise to yield broadband dispersion curves at 0.3–6 Hz.This provides insightful results at high frequencies,at which less information can be obtained through the passive-source beamforming.The combing phase velocities from active-source with those obtained from ambient noise provide a better constrain on the shallow structure.Based on the combined fundamental mode dispersion curves at 28 excitation points,the S-wave velocity structure below the dense array is obtained by depth inversion.Due to the constraints imposed by the high-frequency information from active source,the estimated vS30 are more reliable and can be used to the site classification.
基金supported by the National Key Research and Development Program of China(2021YFC2500200,2021YFC2500204)the Key Technologies Research and Development Program of Guangdong Province(2023B1111030004)the Guizhou Science and Technology Department(QKHPTRC2018-5636-2,QKHCG2023-ZD010).
文摘Dear Editor,Heart failure(HF)is a common multi-faceted and life-threatening syndrome,of which up to 23%occur acute kidney injury(AKI)[1].HF-related AKI is largely overlooked or delayed in identification[2].Approximately 85%of AKI cases that occurred during cardiac hospitalization in China were either ignored or identifi ed too late[3].Currently,there are no specific guidelines for the management of HF-related AKI.Hence,it is essential to identify patients at the risk of developing AKI and intervene promptly.
