Choosing the Jingle well in Shanxi as the research object, this paper discusses the reproducibility problem of well water level precursor waves. The results show that the start time and fluctuation cycle before simila...Choosing the Jingle well in Shanxi as the research object, this paper discusses the reproducibility problem of well water level precursor waves. The results show that the start time and fluctuation cycle before similar earthquakes are highly reproducible,the ratio of which is up to 63. 1%. The fluctuation form and amplitude before some similar earthquakes are of certain similarity,but earthquakes with all precursor wave features being similar were not found in the research scope. The reason may be related to the origin and transmission route of the precursor wave as well as the properties of the seismic source area of similar earthquakes.展开更多
Simultaneous measurements from THEMIS spacecraft, GOES11 and ground stations （Canadian Array for Realtime Investiga tions of Magnetic Activity or CARISMA, and 210 magnetic meridian or MM） on March 18, 2009 allow the...Simultaneous measurements from THEMIS spacecraft, GOES11 and ground stations （Canadian Array for Realtime Investiga tions of Magnetic Activity or CARISMA, and 210 magnetic meridian or MM） on March 18, 2009 allow the study of dynamic processes in the nearEarth magnetotail and corresponding Pi2 pulsations on the ground in great detail. Fast earthward flows along with traveling Alfv6n waves and fast mode waves in the Pi2 band were observed by three Time History of Events and Macroscale Interactions during Substorms （THEM/S） probes （P3, P4 and P5） in the nearEarth plasmasbeet. At the mid to highlatitude nightside, the CARISMA stations located near the foot points of the three probes recorded Pi2s with two periods, about 80 s after the earthward fast flows observed by the P4 probe. The longperiod Pi2 （140-150 s） belongs to the transient response Pi2 （TR Pi2）, since the travel time of the Alfv6n waves between the plasma sheet and CARISMA stations is very close to half the period of the longperiod Pi2. The shortperiod Pi2 （60-80 s） has the same period band as the perpendicular velocity of the fast flows, which indicates that it may relate to the inertial current caused by periodic braking of the earthward fast flows. The 210 MM stations located at the lowlatitude duskside also observed Pi2s with the same start time, waveform and frequency, about 120 s after the earthward fast flows. Strong poloidal oscillations are shown by GOES11 （23 MLT） and the compressional component （Bb） is highly correlated with H components of the 210 MM stations, whereas the other two components （Br and Be） are not. These results confirm that the lowlatitude Pi2s are generated by cavity mode resonance, which is driven by an impulsive broadband source in the nearEarth magnetotail.展开更多
In this paper, a mathematical model to study the impact of Twitter in controlling infectious disease is proposed. The model includes the dynamics of ＂tweets＂ which may enhance awareness of the disease and cause beha...In this paper, a mathematical model to study the impact of Twitter in controlling infectious disease is proposed. The model includes the dynamics of ＂tweets＂ which may enhance awareness of the disease and cause behavioral changes among the public, thus reducing the transmission of the disease. Furthermore, the model is improved by introducing a time delay between the outbreak of disease and the release of Twitter messages. The basic reproduction number and the conditions for the stability of the equilibria are derived. It is shown that the system undergoes Hopf bifurcation when time delay is increased. Finally, numerical simulations are given to verify the analytical results.展开更多
基金funded by Science and Technology Tackling Project of Shanxi Province ( 2006031106)the Joint Earthquake Science Foundation of China Earthquake Administration( A08051)Natural Sciences Foundation of Shanxi Province ( 2011011027)
文摘Choosing the Jingle well in Shanxi as the research object, this paper discusses the reproducibility problem of well water level precursor waves. The results show that the start time and fluctuation cycle before similar earthquakes are highly reproducible,the ratio of which is up to 63. 1%. The fluctuation form and amplitude before some similar earthquakes are of certain similarity,but earthquakes with all precursor wave features being similar were not found in the research scope. The reason may be related to the origin and transmission route of the precursor wave as well as the properties of the seismic source area of similar earthquakes.
基金supported by the National Key Basic Research Program of China (Grant No.2012CB825604)the National Natural Science Foundation of China (Grant Nos.41104093 & 41204122).
文摘Simultaneous measurements from THEMIS spacecraft, GOES11 and ground stations （Canadian Array for Realtime Investiga tions of Magnetic Activity or CARISMA, and 210 magnetic meridian or MM） on March 18, 2009 allow the study of dynamic processes in the nearEarth magnetotail and corresponding Pi2 pulsations on the ground in great detail. Fast earthward flows along with traveling Alfv6n waves and fast mode waves in the Pi2 band were observed by three Time History of Events and Macroscale Interactions during Substorms （THEM/S） probes （P3, P4 and P5） in the nearEarth plasmasbeet. At the mid to highlatitude nightside, the CARISMA stations located near the foot points of the three probes recorded Pi2s with two periods, about 80 s after the earthward fast flows observed by the P4 probe. The longperiod Pi2 （140-150 s） belongs to the transient response Pi2 （TR Pi2）, since the travel time of the Alfv6n waves between the plasma sheet and CARISMA stations is very close to half the period of the longperiod Pi2. The shortperiod Pi2 （60-80 s） has the same period band as the perpendicular velocity of the fast flows, which indicates that it may relate to the inertial current caused by periodic braking of the earthward fast flows. The 210 MM stations located at the lowlatitude duskside also observed Pi2s with the same start time, waveform and frequency, about 120 s after the earthward fast flows. Strong poloidal oscillations are shown by GOES11 （23 MLT） and the compressional component （Bb） is highly correlated with H components of the 210 MM stations, whereas the other two components （Br and Be） are not. These results confirm that the lowlatitude Pi2s are generated by cavity mode resonance, which is driven by an impulsive broadband source in the nearEarth magnetotail.
文摘In this paper, a mathematical model to study the impact of Twitter in controlling infectious disease is proposed. The model includes the dynamics of ＂tweets＂ which may enhance awareness of the disease and cause behavioral changes among the public, thus reducing the transmission of the disease. Furthermore, the model is improved by introducing a time delay between the outbreak of disease and the release of Twitter messages. The basic reproduction number and the conditions for the stability of the equilibria are derived. It is shown that the system undergoes Hopf bifurcation when time delay is increased. Finally, numerical simulations are given to verify the analytical results.
