The circular explosion wave produced by the abrupt discharge of gas from a high-temperature heat source serves as a crucial model for addressing explosion phenomena in compressible flow.The reflection of the primary s...The circular explosion wave produced by the abrupt discharge of gas from a high-temperature heat source serves as a crucial model for addressing explosion phenomena in compressible flow.The reflection of the primary shock and its propagation within a confined domain are studied both theoretically and numerically in this research.Under the assumption of strong shock,the scaling law governing propagation of the main shock is proposed.The dimensionless frequency of reflected shock propagation is associated with the confined distance.The numerical simulation for the circular explosion problem in a confined domain is performed for validation.Under the influence of confinement,the principal shock wave systematically undergoes reflection within the domain until it weakens,leading to the non-monotonic attenuation of kinetic energy in the explosion fireball and periodic oscillations of the fireball volume with a certain frequency.The simulation results indicate that the frequency of kinetic energy attenuation and the volume oscillation of the explosive fireball align consistently with the scaling law.展开更多
Current practice uses predictive models to extrapolate long-period response spectra based on far-field recordings in moderate and weak earthquakes. However, the spectra are not long enough and the data are often not r...Current practice uses predictive models to extrapolate long-period response spectra based on far-field recordings in moderate and weak earthquakes. However, the spectra are not long enough and the data are often not reliable, which means that the seismic design code cannot accurately define seismic design requirements for long-period structures. The near-field recordings in the main-shock of the Chi-Chi earthquake have a large signal-to-noise ratio （SNR）, which makes them suitable for studying the long-period acceleration response spectrum up to 20 sec. The acceleration response spectra from 246 stations within 120 km of the causative fault are statistically analyzed in this paper. The influence of distance and site conditions on long-period response spectrum is discussed, and the shapes of the amplification spectra are compared with the standard spectra specified in the seismic design code of China. Finally, suggestions for future revisions to the code are proposed.展开更多
More than a half of strong earthquakes in the world are located in shallow depth at the subducting plate boundary in squeezed zones. Owing to the difference in speed between the moving sea plates, the strain energy is...More than a half of strong earthquakes in the world are located in shallow depth at the subducting plate boundary in squeezed zones. Owing to the difference in speed between the moving sea plates, the strain energy is accumulated and released cyclically in squeezed zones. Several methods were developed to analyze the medium-and short-term potential of main shocks. These methods can be classified into (1) less data systems using the theory of grey model for earthquake prediction, (2) quasi-periodic systems using earthquake activity analysis, (3) systems of grouped activity using order analysis, and (4) nonlinear systems using back propagation (BP) of neural network for prediction analysis. Based upon these analytic methods, risk maps for the prediction of strong earthquakes can be drawn using the records of strong earthquakes in Taiwan for the past 100 years. These risk maps include (1) a seismic risk map, (2) a loss risk map, (3) a hazard degree map, and (4) a loss degree map. These risk maps make it possible to do a medium-term prediction of main shocks on the 10-year scale.展开更多
A 53-year-old male with chest pain complicated with cardiogenic shock was presented to the emergency department. The electrocardiogram showed features of acute myocardial infarction due to left main coronary artery oc...A 53-year-old male with chest pain complicated with cardiogenic shock was presented to the emergency department. The electrocardiogram showed features of acute myocardial infarction due to left main coronary artery occlusion,and minor ST-segment deviations followed by tall T waves in precordial leads with concomitant left anterior fascicular block. Emergency coronary angiogram revealed left main coronary artery complete occlusion without collateral circulation. Percutaneous intervention of the left main coronary artery was then carried out. The ECG features of a left main occlusion were discussed with this case report.[S Chin J Cardiol 2019;20(3):197-200]展开更多
基金the National Natural Science Foundation of China(Nos.11988102,92052201,11825204,12032016,12372220,and 12372219)。
文摘The circular explosion wave produced by the abrupt discharge of gas from a high-temperature heat source serves as a crucial model for addressing explosion phenomena in compressible flow.The reflection of the primary shock and its propagation within a confined domain are studied both theoretically and numerically in this research.Under the assumption of strong shock,the scaling law governing propagation of the main shock is proposed.The dimensionless frequency of reflected shock propagation is associated with the confined distance.The numerical simulation for the circular explosion problem in a confined domain is performed for validation.Under the influence of confinement,the principal shock wave systematically undergoes reflection within the domain until it weakens,leading to the non-monotonic attenuation of kinetic energy in the explosion fireball and periodic oscillations of the fireball volume with a certain frequency.The simulation results indicate that the frequency of kinetic energy attenuation and the volume oscillation of the explosive fireball align consistently with the scaling law.
基金National Natural Science Foundation of China Under Grant No.40374017
文摘Current practice uses predictive models to extrapolate long-period response spectra based on far-field recordings in moderate and weak earthquakes. However, the spectra are not long enough and the data are often not reliable, which means that the seismic design code cannot accurately define seismic design requirements for long-period structures. The near-field recordings in the main-shock of the Chi-Chi earthquake have a large signal-to-noise ratio （SNR）, which makes them suitable for studying the long-period acceleration response spectrum up to 20 sec. The acceleration response spectra from 246 stations within 120 km of the causative fault are statistically analyzed in this paper. The influence of distance and site conditions on long-period response spectrum is discussed, and the shapes of the amplification spectra are compared with the standard spectra specified in the seismic design code of China. Finally, suggestions for future revisions to the code are proposed.
文摘More than a half of strong earthquakes in the world are located in shallow depth at the subducting plate boundary in squeezed zones. Owing to the difference in speed between the moving sea plates, the strain energy is accumulated and released cyclically in squeezed zones. Several methods were developed to analyze the medium-and short-term potential of main shocks. These methods can be classified into (1) less data systems using the theory of grey model for earthquake prediction, (2) quasi-periodic systems using earthquake activity analysis, (3) systems of grouped activity using order analysis, and (4) nonlinear systems using back propagation (BP) of neural network for prediction analysis. Based upon these analytic methods, risk maps for the prediction of strong earthquakes can be drawn using the records of strong earthquakes in Taiwan for the past 100 years. These risk maps include (1) a seismic risk map, (2) a loss risk map, (3) a hazard degree map, and (4) a loss degree map. These risk maps make it possible to do a medium-term prediction of main shocks on the 10-year scale.
文摘A 53-year-old male with chest pain complicated with cardiogenic shock was presented to the emergency department. The electrocardiogram showed features of acute myocardial infarction due to left main coronary artery occlusion,and minor ST-segment deviations followed by tall T waves in precordial leads with concomitant left anterior fascicular block. Emergency coronary angiogram revealed left main coronary artery complete occlusion without collateral circulation. Percutaneous intervention of the left main coronary artery was then carried out. The ECG features of a left main occlusion were discussed with this case report.[S Chin J Cardiol 2019;20(3):197-200]
