Seismic records produced by different seismic sources vary.In this study,we compared the waveform records and time-frequency characteristics of tectonic earthquakes,artificial explosions,and mine collapses in China’s...Seismic records produced by different seismic sources vary.In this study,we compared the waveform records and time-frequency characteristics of tectonic earthquakes,artificial explosions,and mine collapses in China’s Capital Region.The results show that tectonic earthquakes are characterized by stronger S-wave energy than P-wave energy,obvious high-frequency components,and wide frequency bands of P and S waves.Artificial explosions are characterized by greater P-wave amplitude than S-wave amplitude and near-station surface wave development.Mine collapses are characterized by lower overall frequency,more obvious surface waves,and longer duration.We extracted quantitative discriminants based on the analysis of different event records,with 31 feature values in 7 categories(P/S maximum amplitude ratio,high/low frequency energy ratio,P/S spectral ratio,corner frequency,duration,the second-order moment of spectrum,and energy strongest point).A comparison of the ability of these feature values to recognize distinct events showed that the 6-17 Hz P/S spectral ratio was able to completely distinguish artificial explosions from the other two types of events.The S-wave corner frequency performed relatively well in identifying all three types of events,with an accuracy of over 90%.Additionally,a support vector machine was used to comprehensively distinguish multiple features,with an accuracy for all three types of events reaching up to 100%.展开更多
爆炸冲击波作用到人体胸部时,肺部会出现肺出血及肺水肿等症状,这是人体爆炸创伤的主要原因,深入研究很有必要.为了更好地理解爆炸创伤的机理,应研究冲击波与微观组织作用的力学过程,但具有一定的难度.本文从基本的生物膜做起,运用分子...爆炸冲击波作用到人体胸部时,肺部会出现肺出血及肺水肿等症状,这是人体爆炸创伤的主要原因,深入研究很有必要.为了更好地理解爆炸创伤的机理,应研究冲击波与微观组织作用的力学过程,但具有一定的难度.本文从基本的生物膜做起,运用分子动力学研究冲击波对DPPC膜造成的损伤,通过停止活塞来控制冲击波的冲量,观察冲击过程中膜的恢复情况.通过观察不同冲量下冲击波经过膜后磷脂分子及其周围水分子分布,发现随着冲量增大,膜越来越无序混乱,褶皱更严重,疏水区水分子越来越多.将膜冲击过程划为3个阶段,分别为冲击阶段、恢复阶段和后效阶段.发现当冲量大于153 m Pa·s时,在冲击过程中没有观察到膜的损伤恢复.展开更多
Model checking is an algorithmic verification technique that checks automatically whether a given finite
state concurrent system satisfies its temporal specification. The main disadvantage of model checking is state s...Model checking is an algorithmic verification technique that checks automatically whether a given finite
state concurrent system satisfies its temporal specification. The main disadvantage of model checking is state space
explosion problem. In this paper, several important approaches have been proposed for dealing with the state
explosion problem. Such approaches are symbolic, abstraction, partial-order reduction, compositional reasoning,
etc. Then,a number of way are proposed for verifying real-time and hybrid systems using model checking. At last,
several approaches combining model checking and other verification techniques or mathematical methods are consid-
ered.展开更多
文摘Seismic records produced by different seismic sources vary.In this study,we compared the waveform records and time-frequency characteristics of tectonic earthquakes,artificial explosions,and mine collapses in China’s Capital Region.The results show that tectonic earthquakes are characterized by stronger S-wave energy than P-wave energy,obvious high-frequency components,and wide frequency bands of P and S waves.Artificial explosions are characterized by greater P-wave amplitude than S-wave amplitude and near-station surface wave development.Mine collapses are characterized by lower overall frequency,more obvious surface waves,and longer duration.We extracted quantitative discriminants based on the analysis of different event records,with 31 feature values in 7 categories(P/S maximum amplitude ratio,high/low frequency energy ratio,P/S spectral ratio,corner frequency,duration,the second-order moment of spectrum,and energy strongest point).A comparison of the ability of these feature values to recognize distinct events showed that the 6-17 Hz P/S spectral ratio was able to completely distinguish artificial explosions from the other two types of events.The S-wave corner frequency performed relatively well in identifying all three types of events,with an accuracy of over 90%.Additionally,a support vector machine was used to comprehensively distinguish multiple features,with an accuracy for all three types of events reaching up to 100%.
文摘爆炸冲击波作用到人体胸部时,肺部会出现肺出血及肺水肿等症状,这是人体爆炸创伤的主要原因,深入研究很有必要.为了更好地理解爆炸创伤的机理,应研究冲击波与微观组织作用的力学过程,但具有一定的难度.本文从基本的生物膜做起,运用分子动力学研究冲击波对DPPC膜造成的损伤,通过停止活塞来控制冲击波的冲量,观察冲击过程中膜的恢复情况.通过观察不同冲量下冲击波经过膜后磷脂分子及其周围水分子分布,发现随着冲量增大,膜越来越无序混乱,褶皱更严重,疏水区水分子越来越多.将膜冲击过程划为3个阶段,分别为冲击阶段、恢复阶段和后效阶段.发现当冲量大于153 m Pa·s时,在冲击过程中没有观察到膜的损伤恢复.
文摘Model checking is an algorithmic verification technique that checks automatically whether a given finite
state concurrent system satisfies its temporal specification. The main disadvantage of model checking is state space
explosion problem. In this paper, several important approaches have been proposed for dealing with the state
explosion problem. Such approaches are symbolic, abstraction, partial-order reduction, compositional reasoning,
etc. Then,a number of way are proposed for verifying real-time and hybrid systems using model checking. At last,
several approaches combining model checking and other verification techniques or mathematical methods are consid-
ered.
