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181.
《防务技术》2020,16(3):635-641
Among practical metal additives, boron (B) has a high volumetric heating value, making it a promising choice as a fuel additive. Although B can theoretically yield a large amount of energy upon complete combustion, its combustion is retarded by the initial presence of B oxide, which coats the surfaces of B particle. To improve the ignition and combustion properties of B powder, LiOH and NH4F were used as precursors to synthesize uniformly LiF-coated B composites (LiF-B) in situ. The LiF-B mixture was also prepared for comparison using a physical method. X-ray diffraction (XRD), Fourier-transform infrared (FTIR), scanning electron microscope (SEM), and energy-dispersive X-ray spectroscopy (EDS) were used to characterize the morphologies and compositions of the products. The thermal and combustion properties of the samples were characterized by thermal gravity-differential thermal gravity (TG-DTG), differential scanning calorimetry (DSC) and closed bomb experiment. The XRD, FTIR, SEM and EDS results demonstrated the successful preparation of the coated LiF-B sample. The TG-DTG and closed bomb experiment results indicated that the addition of LiF decreased the ignition temperature of B powder, and increasing its reaction efficiency. DSC results show that when LiF-B was added, the released heat of underwater explosive increased by 6727.2, 7280.4 and 3109.6 J/g at heating rates of 5, 10, and 15 °C/min, respectively. Moreover, LiF-B decreased the activation energy of secondary combustion reaction of explosive system as calculated through Kissinger's method by 28.9%, which indicated an excellent catalytic effect for the thermal decomposition of underwater explosive. The results reveal that LiF can improve the combustion efficiency of B powder, thereby increasing the total energy of explosives. The mechanical sensitivity increased slightly after adding LiF-B to the underwater explosive. Compared to the underwater explosive with added B, the mechanical sensitivity of the explosive with added LiF-B was significantly lower. 相似文献
182.
公平与效率视角下的新疆少数民族高等教育发展的分析与思考 总被引:2,自引:0,他引:2
本文从公平与效率视角对新疆少数民族普通高等教育发展进行了分析,指出了新疆少数民族普通高等教育发展中存在的公平与效率问题,为了新疆少数民族高等教育的健康持续发展,对新疆少数民族高等教育发展中存在的效率与公平问题提出了一些建议。 相似文献
183.
采用对舰艇运动的坐标跟踪法,应用灰色预测技术,建立舰艇的灰色预测动态模型。使火炮对舰艇的射击,具有反应速度快、命中精度好、毁伤效益高和便于计算机控制等优点。 相似文献
184.
提出了利用动态精度试验数据,预测近炸引信预制破片弹射击效能的思路,建立了动态精度预测射击效能的数学模型,在较接近实战条件下模拟计算了近炸引信预制破片弹的射击效能.计算结果与实弹射击结果接近,表明该方法能有效预测近炸引信预制破片弹的射击效能,能为射击试验提供高可信度的验前信息,有助于优化射击试验方案的制定,减少试验样本量,降低试验消耗. 相似文献
185.
Nanothermites have been employed as fuel additives in energetic formulations due to their higher en-ergy density over CHNO energetics. Nevertheless, sintering and degradation of nanoparticles signifi-cantly limit the practical use of nanothermites. In this work, combustion characteristic and aging behavior of aluminum/iron oxide (Al/Fe2O3) nanothermite mixtures were investigated in the presence of micron-scale nickel aimed to produce bimetal thermite powders. The results showed that the alumina content in the combustion residue increased from 88.3% for Al/Fe2O3 nanothermite to 96.5% for the nanothermite mixture containing 20 wt%nickel. Finer particle sizes of combustion residue were obtained for the nanothermite mixtures containing nickel, indicative of the reduced agglomeration. Both results suggested a more complete combustion in the bimetal thermite powders. Aging behavior of the nano-thermite mixture was also assessed by measuring the heat of combustion of the mixture before and after aging process. The reduction in heat of combustion of nanothermite mixtures containing nickel was less severe as compared to a significant decrease for the nanothermite mixture without nickel, indicating better aging resistance of the bimetal thermite powders. 相似文献
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针对指挥控制关系网络受到攻击时节点及网络毁伤程度的量化评价问题,首先形式化定义了攻击强度和节点自修复能力函数,在此基础上,分别给出了网络中节点无自修复能力和自修复能力随时间变化时的节点毁伤模型。最后通过仿真计算,得到了节点的失效过程描述以及随机攻击和选择性攻击两种不同攻击目标选择方式下网络效率随攻击时间的变化关系。 相似文献