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排序方式: 共有162条查询结果,搜索用时 15 毫秒
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《防务技术》2022,18(11):1979-1999
A quasi-isentropic study on the process of driving a cylinder with aluminized explosives was carried out to examine the influence of the aluminum (Al) reaction rate on cylinder expansion and the physical parameters of the detonation products. Based on the proposed quasi-isentropic hypothesis and relevant isentropic theories, the characteristic lines of aluminized explosives driving a cylinder were analyzed, and a quasi-isentropic model was established. This model includes the variation of the cylinder wall velocity and the physical parameters of the detonation products with the Al reaction degree. Using previously reported experimental results, the quasi-isentropic model was verified to be applicative and accurate. This model was used to calculate the physical parameters for cylinder experiments with aluminized cyclotrimethylenetrinitramine explosives with 15.0 % and 30.0 % Al content. The results show that this quasi-isentropic model can be used not only to calculate the cylinder expansion rule or Al reaction degree, but also to calculate the physical parameters of the detonation products in the process of cylinder expansion. For explosives with 15.0 % and 30.0 % Al, 24.3 % and 18.5 % of the Al was found to have reacted at 33.9 μs and 34.0 μs, respectively. The difference in Al content results in different reaction intensity, occurrence time, and duration of two forms of reaction (diffusion and kinetic) between the Al powder and the detonation products; the post-detonation burning reaction between the Al powder and the detonation products prolongs the positive pressure action time, resulting in a continuous rise in temperature after detonation. 相似文献
53.
张朋召 《中国人民武装警察部队学院学报》2014,30(11):78-81
学位论文是衡量研究生培养质量的重要标志之一。鉴于开题、答辩等重要论文质量监控环节出现的走过场、走形式现象,提出将问题归零制度引入学位论文质量保障体系之中。通过明确归零范围、基本要求、责任主体和处理程序,构建了保障学位论文质量的归零制度设想。 相似文献
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We study the behavior of defense spending in Switzerland over 1975–2001. Our main interest is in determining how neutrality in international affairs (non‐membership in military alliances) affects defense spending. We find that neutrality is associated with a perception of lower levels of external threat; hence it confers economic benefits in the form of a smaller defense burden. However, neutrality does not fully insulate a country from variations in the level of external threat in the global system as perceived by members of military alliances. Swiss defense spending has tracked very closely the spending trends – but at a lower average level – of the United States and other NATO countries. To the extent that post‐Cold War threats, such as international terrorism, materialize primarily in the context of existing security alliances, Swiss military spending patterns observed in 1975–2001 are likely to remain the same in the future. 相似文献
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The main objective of the paper is to decipher the military expenditure–economic growth relationship, taking the level of economic development (income) into consideration. Our findings suggest the following: (i) military expenditure has a significantly negative relationship to economic growth for the 23 countries with initial incomes (threshold variable) less than or equal to $475.93; (ii) when the threat level is heightened, economic growth (23 countries) is expected to decrease. However, military expenditure in the presence of sufficiently large threats increases growth; (iii) for the remaining 69 countries whose initial incomes (real GDP per capita in 1992 price) exceed $475.93, no significant relationship exists whether the threat variable is taken into consideration or not. 相似文献
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提出了一种可用于加油卷盘升降的四杆式液压起落机构的设计方案。分析了四杆式液压起落机构的工作原理,采用复数向量法建立了运动学和动力学数学模型。利用Matlab软件编制了相应的程序进行实例分析和计算,得到了机构关键点的仿真轨迹和有关构件的角位移、角速度及角加速度曲线。运用理论分析计算和软件仿真,验证了机构设计的合理性和方案的可行性。 相似文献
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为了提高恒流源的精度,减少温度对恒流源稳定度的影响,分析了恒流源稳定度不高的原因,比对了恒压源器件,提出了采用高精度恒压源控制电流源的方法实现精密恒流源的思想,给出了电路设计原则、具体电路、原理分析及注意事项,并对压控精密恒流源进行了实验测试.研究方法显著提高了恒流源的精度. 相似文献
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The explosive reaction degree and protection from explosions are concerns in the military field.In this work,the reaction degree of the composition B explosive was investigated experimentally.Multi-layered compound structures were used as barriers to weaken the blast loads.A comprehensive experiment using a high-speed camera and image processing techniques,side witness plates,and bottom witness plates was presented.Using the experimental fragment velocities,fragment piercing patterns,and damage characteristics,the reaction degree of the explosive impeded by different multi-layered com-pound structures could be precisely differentiated.Reaction parameters of the explosive obstructed by compound structures were obtained by theoretical analysis and numerical simulations.Unlike the common method in which the explosive reaction degree is only distinguished based on the initial pressure amplitude transmitted into the explosive,a following shock wave reflected from the side steel casing was also considered.Different detonation growth paths in the explosive formed.Therefore,all these shock wave propagation characteristics must be considered to analyze the explosive response impeded by compound structures. 相似文献