New studies suggest that the Kaili Biota in southwestern China's Guizhou Province could be the third revealing evidence for the spectacular Cambrian Explosion of life about 530 million years ago, next to the Burge...New studies suggest that the Kaili Biota in southwestern China's Guizhou Province could be the third revealing evidence for the spectacular Cambrian Explosion of life about 530 million years ago, next to the Burgess Shale Biota of Canada, found in 1909,and the Chengjiang Biota, brought to light in Yunnan Province, China,in 1984.展开更多
Breeding bird abundance, species richness, evenness, diversity, composition, productivity, and survivorship were determined near a high-explosive detonation site at Los Alamos National Laboratory, New Mexico, USA, dur...Breeding bird abundance, species richness, evenness, diversity, composition, productivity, and survivorship were determined near a high-explosive detonation site at Los Alamos National Laboratory, New Mexico, USA, during pre-operation (1997-1999) and operation (2000-2014) periods. The operation periods consisted of detonations ( 0.05) in mean avian abundance and species evenness in any of the operation periods as compared with the pre-operation period. Species richness and diversity were significantly higher (p < 0.05) during the vessel containment period (2007-2014) than the pre-operation period. The time period of this study coincided with a wildfire (2000), a bark beetle infestation (2002), and two periods of drought (Nov 1999-Mar 2004 and Dec 2005-Dec 2014) that affected the study area. Analysis of aerial photos determined that the average percent canopy cover of mature ponderosa pines (Pinus ponderosa) within 100 feet of mist net sites declined from 12% to 3% between 1991 and 2014 and the percent cover of shrubs slightly increased. The percent similarity in presence/abundance between the pre-operation avian community and avian community during the open air, foam containment, and vessel containment periods were 59%, 63% and 68% respectively. Two bird species associated with large trees became less common over the study period (capture rate dropped below 2.0 adults per 600 net-hours relative to the pre-operations period), and four bird species associated with edge and scrub habitats became more common over the study period (capture rate increased to more than 2.0 adults per 600 net-hours relative to the pre-operations period). Bird demographics (productivity and survival) were not negatively affected by the initiation of firing site operations. The increase in diversity and the change in bird species composition over time were probably related to the change in vegetation from a woodland to a more open woodland/shrub environment.展开更多
The time-dependent Jones Wilkins-Lee equation products for aluminized explosives. To obtain the of state （JWL-EOS） is applied to describe detonation state time-dependent JWL-EOS parameters, cylinder tests and underw...The time-dependent Jones Wilkins-Lee equation products for aluminized explosives. To obtain the of state （JWL-EOS） is applied to describe detonation state time-dependent JWL-EOS parameters, cylinder tests and underwater explosion experiments are performed. According to the result of the wall radial velocity in cylinder tests and the shock wave pressures in underwater explosion experiments, the time-dependent JWL-EOS parameters are determined by iterating these variables in AUTODYN hydroeode simulations until the experimental values are reproduced. In addition, to verify the reliability of the derived JWL-EOS parameters, the aluminized explosive experiment is conducted in concrete. The shock wave pressures in the affected concrete bodies are measured by using manganin pressure sensors, and the rod velocity is obtained by using a high-speed camera. Simultaneously, the shock wave pressure and the rod velocity are calculated by using the derived time-dependent JWL equation of state. The calculated results are in good agreement with the experimental data.展开更多
The new numerical algorithms in SUPER/CESE and their applications in explosion mechanics are studied. The researched al-gorithms and models include an improved CE/SE (space-time Conservation Element and Solution Eleme...The new numerical algorithms in SUPER/CESE and their applications in explosion mechanics are studied. The researched al-gorithms and models include an improved CE/SE (space-time Conservation Element and Solution Element) method,a local hybrid particle level set method,three chemical reaction models and a two-fluid model. Problems of shock wave reflection over wedges,explosive welding,cellular structure of gaseous detonations and two-phase detonations in the gas-droplet system are simulated by using the above-mentioned algorithms and models. The numerical results reveal that the adopted algorithms have many advantages such as high numerical accuracy,wide application field and good compatibility. The numerical algo-rithms presented in this paper may be applied to the numerical research of explosion mechanics.展开更多
文摘New studies suggest that the Kaili Biota in southwestern China's Guizhou Province could be the third revealing evidence for the spectacular Cambrian Explosion of life about 530 million years ago, next to the Burgess Shale Biota of Canada, found in 1909,and the Chengjiang Biota, brought to light in Yunnan Province, China,in 1984.
文摘Breeding bird abundance, species richness, evenness, diversity, composition, productivity, and survivorship were determined near a high-explosive detonation site at Los Alamos National Laboratory, New Mexico, USA, during pre-operation (1997-1999) and operation (2000-2014) periods. The operation periods consisted of detonations ( 0.05) in mean avian abundance and species evenness in any of the operation periods as compared with the pre-operation period. Species richness and diversity were significantly higher (p < 0.05) during the vessel containment period (2007-2014) than the pre-operation period. The time period of this study coincided with a wildfire (2000), a bark beetle infestation (2002), and two periods of drought (Nov 1999-Mar 2004 and Dec 2005-Dec 2014) that affected the study area. Analysis of aerial photos determined that the average percent canopy cover of mature ponderosa pines (Pinus ponderosa) within 100 feet of mist net sites declined from 12% to 3% between 1991 and 2014 and the percent cover of shrubs slightly increased. The percent similarity in presence/abundance between the pre-operation avian community and avian community during the open air, foam containment, and vessel containment periods were 59%, 63% and 68% respectively. Two bird species associated with large trees became less common over the study period (capture rate dropped below 2.0 adults per 600 net-hours relative to the pre-operations period), and four bird species associated with edge and scrub habitats became more common over the study period (capture rate increased to more than 2.0 adults per 600 net-hours relative to the pre-operations period). Bird demographics (productivity and survival) were not negatively affected by the initiation of firing site operations. The increase in diversity and the change in bird species composition over time were probably related to the change in vegetation from a woodland to a more open woodland/shrub environment.
基金Supported by the National Natural Science Foundation of China under Grant No 11172042
文摘The time-dependent Jones Wilkins-Lee equation products for aluminized explosives. To obtain the of state （JWL-EOS） is applied to describe detonation state time-dependent JWL-EOS parameters, cylinder tests and underwater explosion experiments are performed. According to the result of the wall radial velocity in cylinder tests and the shock wave pressures in underwater explosion experiments, the time-dependent JWL-EOS parameters are determined by iterating these variables in AUTODYN hydroeode simulations until the experimental values are reproduced. In addition, to verify the reliability of the derived JWL-EOS parameters, the aluminized explosive experiment is conducted in concrete. The shock wave pressures in the affected concrete bodies are measured by using manganin pressure sensors, and the rod velocity is obtained by using a high-speed camera. Simultaneously, the shock wave pressure and the rod velocity are calculated by using the derived time-dependent JWL equation of state. The calculated results are in good agreement with the experimental data.
基金supported by the National Natural Science Foundation of China (Grant Nos. 10572002 and 10732010)
文摘The new numerical algorithms in SUPER/CESE and their applications in explosion mechanics are studied. The researched al-gorithms and models include an improved CE/SE (space-time Conservation Element and Solution Element) method,a local hybrid particle level set method,three chemical reaction models and a two-fluid model. Problems of shock wave reflection over wedges,explosive welding,cellular structure of gaseous detonations and two-phase detonations in the gas-droplet system are simulated by using the above-mentioned algorithms and models. The numerical results reveal that the adopted algorithms have many advantages such as high numerical accuracy,wide application field and good compatibility. The numerical algo-rithms presented in this paper may be applied to the numerical research of explosion mechanics.
