提高防爆装备的抗爆性能已经成为热门的研究课题,目前的防爆装备主要采用金属制成,一般重量大,采用点阵夹芯结构可以实现轻量化。点阵夹芯结构具有良好的能量吸收效率和在高应变率下的优异力学性能,但以往的防爆研究未考虑过不易变形的...提高防爆装备的抗爆性能已经成为热门的研究课题,目前的防爆装备主要采用金属制成,一般重量大,采用点阵夹芯结构可以实现轻量化。点阵夹芯结构具有良好的能量吸收效率和在高应变率下的优异力学性能,但以往的防爆研究未考虑过不易变形的半球型点阵,复合了聚氨酯泡沫的抗爆夹芯结构研究更为少见。鉴于此,结合聚氨酯泡沫缓冲吸能以及半球结构的拱形抗变形能力提出一种新型的聚氨酯-半球夹芯结构,并且采用实验和数值模拟相结合的方法对聚氨酯-半球夹芯结构在爆炸冲击波载荷下的动态响应进行研究。研究结果表明,在500 g TNT当量0.65 m爆炸冲击下,相近面密度的聚氨酯-半球夹芯结构中心点位移最小,相较于铝板和纯半球夹芯板分别减小了30%和35%,纯半球夹芯板虽然吸能最多但是变形最大,聚氨酯-半球夹芯结构和铝板的吸能分别为纯半球夹芯板的85%和63%,相较于铝板,聚氨酯-半球夹芯结构在保证能量吸收效率的同时能有效减少靶板速度和应力集中。展开更多
The Antarctic polar front region in the Southern Ocean is known to be most productive. We studied the phytoplankton community structure in the Indian sector at this frontal location during late austral summer (Februar...The Antarctic polar front region in the Southern Ocean is known to be most productive. We studied the phytoplankton community structure in the Indian sector at this frontal location during late austral summer (February, 2009) onboard R/V Akademic Boris Petrov. We used the phytoplankton and microheterotrophs abundance, as also the associated physico-chemical parameters to explain the low phytoplankton abundance in the study region. This study emphasizes the shift of phytoplankton, from large (>10 μm) to small (<10 μm) size. The phytoplankton abundance appears to be controlled by physical parameters and by nutrient concentrations and also by the microheterotrophs (ciliates and dinoflagellates) which exert a strong grazing pressure. This probably reduces small (<10 μm) and large (>10 μm) phytoplankton abundance during the late austral summer. This study highlights the highly productive polar front nevertheless becomes a region of low phytoplankton abundance, due to community shifts towards pico-phytoplankton (<10 μm) during late austral summer.展开更多
文摘提高防爆装备的抗爆性能已经成为热门的研究课题,目前的防爆装备主要采用金属制成,一般重量大,采用点阵夹芯结构可以实现轻量化。点阵夹芯结构具有良好的能量吸收效率和在高应变率下的优异力学性能,但以往的防爆研究未考虑过不易变形的半球型点阵,复合了聚氨酯泡沫的抗爆夹芯结构研究更为少见。鉴于此,结合聚氨酯泡沫缓冲吸能以及半球结构的拱形抗变形能力提出一种新型的聚氨酯-半球夹芯结构,并且采用实验和数值模拟相结合的方法对聚氨酯-半球夹芯结构在爆炸冲击波载荷下的动态响应进行研究。研究结果表明,在500 g TNT当量0.65 m爆炸冲击下,相近面密度的聚氨酯-半球夹芯结构中心点位移最小,相较于铝板和纯半球夹芯板分别减小了30%和35%,纯半球夹芯板虽然吸能最多但是变形最大,聚氨酯-半球夹芯结构和铝板的吸能分别为纯半球夹芯板的85%和63%,相较于铝板,聚氨酯-半球夹芯结构在保证能量吸收效率的同时能有效减少靶板速度和应力集中。
基金Supported by the Ministry of Earth Science(MoES),New Delhi,Indiaone of the ongoing projects in National Centre for Antarctic and Ocean Research(NCAOR)(No.36/2012)
文摘The Antarctic polar front region in the Southern Ocean is known to be most productive. We studied the phytoplankton community structure in the Indian sector at this frontal location during late austral summer (February, 2009) onboard R/V Akademic Boris Petrov. We used the phytoplankton and microheterotrophs abundance, as also the associated physico-chemical parameters to explain the low phytoplankton abundance in the study region. This study emphasizes the shift of phytoplankton, from large (>10 μm) to small (<10 μm) size. The phytoplankton abundance appears to be controlled by physical parameters and by nutrient concentrations and also by the microheterotrophs (ciliates and dinoflagellates) which exert a strong grazing pressure. This probably reduces small (<10 μm) and large (>10 μm) phytoplankton abundance during the late austral summer. This study highlights the highly productive polar front nevertheless becomes a region of low phytoplankton abundance, due to community shifts towards pico-phytoplankton (<10 μm) during late austral summer.
