The aftershock activity of the May 12, 2008 Wenchuan Ms8.0 Earthquake Sequence shows an obvious segmented feature. Most of the large aftershocks were distributed in the north and south parts of the aftershock zone. Th...The aftershock activity of the May 12, 2008 Wenchuan Ms8.0 Earthquake Sequence shows an obvious segmented feature. Most of the large aftershocks were distributed in the north and south parts of the aftershock zone. Thrusting was dominant with a small amount of strike-slip component in the south part. The aftershock activity decayed gradually, presenting the sequence features of a mainshock-aftershock pattern. The north part was the ending area of the malnshock fracture where strike-slipping was dominant, showing an obvious swarm feature. Therefore it became the major area for large aftershocks. The modulation of the earth tide on aftershock activity is remarkable; most large aftershocks occur during the period of flood and neap tide. The time period around 16：00 was the dominant occurring time for large aftershocks. The p-value, a parameter of modified Omori formula, increases gradually with time, and reaches about 1 at the end. Based on previous study, the sequence patterns, magnitude of maximum aftershock, as well as the duration of aftershock activity has been discussed. The primary results also show that the magnitude difference between the maiushock and the maximum aftershock is proportional to the rupture size of the maiushock for huge earthquakes of about Ms8.0. This means that when the magnitudes of the earthquakes are nearly the same, large rupture size corresponds to sufficient energy release.展开更多
In this paper we make a comparative investigation of the signatures of shock activities caused by geoeffective interplanetary coronal mass ejections(IC-MEs)and magnetic clouds on the day/night variability of the magne...In this paper we make a comparative investigation of the signatures of shock activities caused by geoeffective interplanetary coronal mass ejections(IC-MEs)and magnetic clouds on the day/night variability of the magnetospheric convective electric field(MCEF)during solar cycles 23-24.The investigation is carried out with reference to reconnection phenomena between interplane-tary magnetic field lines(IMF)and geomagnetic field lines,taking into ac-count the duration of geomagnetic effects.During days of shock or magnetic cloud activity whose effects last one(1)day,the MCEF begin and end the day in a decreasing phase.During two-day activities,MCEF begin and end the day in an increasing phase.During three-day activities,MCEFs start the day in a decreasing phase and end the day in an increasing phase.The daily mean val-ues of the MCEF during shock periods caused by geoeffective ICMEs are 0.1260966 mV/m,0.14829124 mV/m and 0.21189352 mV/m respectively for shock activities lasting one(1)day,two(2)days and three(3)days.On the other hand,the average daily intensities of the MCEF on days of disturbance caused by magnetic clouds are 0.0932402 mV/m,0.08539255 mV/m and 0.0820986 mV/m respectively for magnetic clouds whose effects last one(1)day,two(2)days and three(3)days.The activity of magnetic clouds on mag-netospheric convection appears to be correlated with both shock activity and sunspot activity.The geoeffective ICMEs responsible for the shock activity are more geoefficient than the magnetic clouds,which suggests that the Bz com-ponent of the orientation IMF is more durable in a southerly orientation and stronger in intensity on days of shock activity than on days of geomagnetic disturbance caused by magnetic clouds.展开更多
Children exhibit unique activity patterns in classrooms,and their movements influence the resuspension of particulate matter,thereby increasing the risk of inhalation.To quantify children’s activity patterns and part...Children exhibit unique activity patterns in classrooms,and their movements influence the resuspension of particulate matter,thereby increasing the risk of inhalation.To quantify children’s activity patterns and particulate matter inhalation doses,we measured particulate matter concentrations and tracked the recess activities of 194 children in two primary schools.YOLO v9 combined with the DeepSORT algorithm was used to identify and track the children in the videos,thereby calculating the speed and duration of each child.Statistical analysis revealed that classroom activities were highly transitory and predominantly of light intensity.The proportion of light-intensity physical activity in this study was 7%–15%higher than that reported in previous studies,attributable to high occupant density,limited activity space,and characteristics of the Chinese education environment.The median durations of recess activities decreased from light-intensity(4.7 s)to moderate-intensity(2.5 s)and vigorous-intensity activities(2.2 s).Furthermore,children’s activity speed and duration were strongly associated with variations in indoor PM2.5 concentrations.Additionally,the daily inhalation dose during recess decreased with increasing age,being 14.67%lower in the middle age group and 30.64%lower in the upper age group compared to the lower age group.Our analysis provides a valuable reference for assessing the health risks caused by particulate matter and for more effective measures to improve the classroom environment.展开更多
基金sponsored jointly by the Earthquake Scientific Research Program(200708020)the State Scientific and Technologic Support Programof the tenth"Five-Year Plan"(200704032006BAC01B030202)
文摘The aftershock activity of the May 12, 2008 Wenchuan Ms8.0 Earthquake Sequence shows an obvious segmented feature. Most of the large aftershocks were distributed in the north and south parts of the aftershock zone. Thrusting was dominant with a small amount of strike-slip component in the south part. The aftershock activity decayed gradually, presenting the sequence features of a mainshock-aftershock pattern. The north part was the ending area of the malnshock fracture where strike-slipping was dominant, showing an obvious swarm feature. Therefore it became the major area for large aftershocks. The modulation of the earth tide on aftershock activity is remarkable; most large aftershocks occur during the period of flood and neap tide. The time period around 16：00 was the dominant occurring time for large aftershocks. The p-value, a parameter of modified Omori formula, increases gradually with time, and reaches about 1 at the end. Based on previous study, the sequence patterns, magnitude of maximum aftershock, as well as the duration of aftershock activity has been discussed. The primary results also show that the magnitude difference between the maiushock and the maximum aftershock is proportional to the rupture size of the maiushock for huge earthquakes of about Ms8.0. This means that when the magnitudes of the earthquakes are nearly the same, large rupture size corresponds to sufficient energy release.
文摘In this paper we make a comparative investigation of the signatures of shock activities caused by geoeffective interplanetary coronal mass ejections(IC-MEs)and magnetic clouds on the day/night variability of the magnetospheric convective electric field(MCEF)during solar cycles 23-24.The investigation is carried out with reference to reconnection phenomena between interplane-tary magnetic field lines(IMF)and geomagnetic field lines,taking into ac-count the duration of geomagnetic effects.During days of shock or magnetic cloud activity whose effects last one(1)day,the MCEF begin and end the day in a decreasing phase.During two-day activities,MCEF begin and end the day in an increasing phase.During three-day activities,MCEFs start the day in a decreasing phase and end the day in an increasing phase.The daily mean val-ues of the MCEF during shock periods caused by geoeffective ICMEs are 0.1260966 mV/m,0.14829124 mV/m and 0.21189352 mV/m respectively for shock activities lasting one(1)day,two(2)days and three(3)days.On the other hand,the average daily intensities of the MCEF on days of disturbance caused by magnetic clouds are 0.0932402 mV/m,0.08539255 mV/m and 0.0820986 mV/m respectively for magnetic clouds whose effects last one(1)day,two(2)days and three(3)days.The activity of magnetic clouds on mag-netospheric convection appears to be correlated with both shock activity and sunspot activity.The geoeffective ICMEs responsible for the shock activity are more geoefficient than the magnetic clouds,which suggests that the Bz com-ponent of the orientation IMF is more durable in a southerly orientation and stronger in intensity on days of shock activity than on days of geomagnetic disturbance caused by magnetic clouds.
基金supported by the National Natural Science Foundation of China(Grant No.52278090)Ministry of Science and Technology of the People’s Republic of ChinaPrashant Kumar acknowledges the support received through the EPSRC-funded COTRACE/SAMHE project(EP/W001411/1).
文摘Children exhibit unique activity patterns in classrooms,and their movements influence the resuspension of particulate matter,thereby increasing the risk of inhalation.To quantify children’s activity patterns and particulate matter inhalation doses,we measured particulate matter concentrations and tracked the recess activities of 194 children in two primary schools.YOLO v9 combined with the DeepSORT algorithm was used to identify and track the children in the videos,thereby calculating the speed and duration of each child.Statistical analysis revealed that classroom activities were highly transitory and predominantly of light intensity.The proportion of light-intensity physical activity in this study was 7%–15%higher than that reported in previous studies,attributable to high occupant density,limited activity space,and characteristics of the Chinese education environment.The median durations of recess activities decreased from light-intensity(4.7 s)to moderate-intensity(2.5 s)and vigorous-intensity activities(2.2 s).Furthermore,children’s activity speed and duration were strongly associated with variations in indoor PM2.5 concentrations.Additionally,the daily inhalation dose during recess decreased with increasing age,being 14.67%lower in the middle age group and 30.64%lower in the upper age group compared to the lower age group.Our analysis provides a valuable reference for assessing the health risks caused by particulate matter and for more effective measures to improve the classroom environment.
