Gas metal arc welding of high nitrogen stainless steel with Ar-N2-O2 ternary shielding gas

High nitrogen stainless steel with nitrogen content of 0.75％was welded by gas metal arc welding with Ar—N2-O2 ternary shielding gas. The effect of the ternary shielding gas on the retention and improvement of nitrogen content in the weld was identified. Surfacing test was conducted first to compare the ability of O2 and CO2 in prompting nitrogen dissolution. The nitrogen content of the surfacing metal with O2 is slightly higher than CO2. And then Ar—N2-O2 shielding gas was applied to weld high nitrogen stainless steel. After using N2-containing shielding gas, the nitrogen content of the weld was improved by 0.1 wt％. As N2 continued to increase, the increment of nitrogen content was not obvious, but the ferrite decreased from the top to the bottom. When the proportion of N2 reached 20％, a full austenitic weld was obtained and the tensile strength was improved by 8.7％. Combined with the results of surfacing test and welding test, it is concluded that the main effect of N2 is to inhibit the escape of nitrogen and suppress the ni-trogen diffusion from bottom to the top in the molten pool.     

A novel method for determination of lethal radius for high-explosive artillery projectiles

A new model has been defined that enables the estimation of the lethal radius (radius of efficiency) of HE (High Explosive) artillery projectiles against human targets. The model is made of several modules: CAD (Computer Aided Design) modeling, fragment mass distribution estimation, fragment initial velocity prediction, fragment trajectory calculation, effective fragment density estimation, and high explosive projectile lethal radius estimation. The results were compared with the experimental results obtained based on tests in the arena used in our country, and the agreement of the results was good. This model can be used in any terminal-ballistics scenario for high explosive projectiles since it is general, para-metric, fast and relatively easy to implement.     

基于HLA的潜舰对抗模拟训练系统的设计与实现

针对水面舰艇与潜艇对抗模拟训练及其作战环境,提出了基于高层体系结构(HLA)的仿真系统设计方案,设计了由水面舰艇、潜艇、直升机、鱼雷等成员组成的潜舰对抗模拟训练系统,并给出了组成联邦的各成员功能和OMT的设计方法,最后分析了潜舰对抗模拟系统的仿真过程,利用VR-Link工具库给出了部分功能的实现代码。在潜舰对抗模拟训练系统的开发中证明该设计是可行的,并且本项研究对其他领域内基于HLA的仿真系统构建和开发具有参考价值。     

拦截高速机动目标的最优制导律

对于远距离拦截高速、大机动目标,不仅拦截弧段长,拦截飞行时间也更久。拦截弹在飞行过程中的能量管理与优化问题,也是在拦截制导律设计时必须要考虑的问题。将非线性弹目运动关系降阶简化后,运用最优控制理论,将能量管理纳入考虑中,得出针对高速、机动目标的最优制导律,且可以满足终端碰撞角约束。通过引入分段线性和指数两种形式的阻尼,使得导弹在拦截高速高加速目标时,对目标机动的敏感度随弹目距离变化,从而达到能量管理的目的。通过二维非线性仿真验证了制导律的性能。     

利用RLC电路合成高压方波脉冲

基于过阻尼RLC电路分时放电,提出了一种新型高压方波脉冲产生方法。理论分析表明过阻尼RLC电路产生的双指数电压波与PFL产生的方形电压波具有类似的上升沿和平顶。电路模拟表明通过人工过零技术可以对双指数电压波进行截尾,从而形成完整的高压方波脉冲。建立了原理验证性样机,由两组RLC电路构成,每组电路包含一台400 nF脉冲电容器和一只三电极场畸变气体开关,两组电路共用一个上升沿调节电感。实验证明样机可以在250 Ω电阻负载上输出幅值17 kV,平顶宽度330 ns~5.8 μs,上升沿100~ 350 ns 的单极性高压方波脉冲。该方法适应性强,对负载变化不敏感,同时具有良好的可调节性,方波上升沿、平顶宽度连续独立可调。     

高能硝胺推进剂的压强指数分析

从高能硝胺推进剂配方组成入手 ,深入研究了各组分参数的变化对该推进剂燃烧性能的影响 ,认为 :高硝胺 ( HMX或 RDX)含量和高硝酸酯增塑剂含量是高能硝胺推进剂 ( NEPE)高压强指数的根本原因。同时指出该类推进剂的燃烧性能的调节将不再仅仅局限于硝胺的催化 ,而应针对硝胺和硝酸酯及 AP的特殊作用进行综合调节     

基于HLA分布式仿真的Web服务化

HLA虽然能够简化各类仿真系统的互操作和重用,但是接口规范与编程语言的绑定、缺乏与商业技术的融合等阻碍了它在商业领域的广泛应用,Web服务具有平台和厂商独立等良好特性,实现基于HLA分布式仿真的Web服务化能够将Web服务的优势附加给HLA.该文在分析了HLA不足和web服务优势的基础上,提出了HLA Web服务化,对比了互操作在两个上下文中的差异,分析了实现HLA Web服务化的三个层次;之后,概述了相关研究,重点讨论了实现Web使能RTI的关键技术问题及其解决方案;最后,设计了原型系统,测试结果显示原型系统能够初步实现RTI的Web服务化.     

战区导弹防御系统(TMD)对抗技术浅析

探讨了战区导弹防御系统(TMD)对抗技术的初步设想与实现方法,重点对TMD系统激光对抗技术和TMD系统红外对抗技术进行了可行性分析论证,介绍了一些具体的光电对抗措施。     

How the High North became Central in NATO Strategy: Revelations from the NATO Archives

From the late 1970s and until the end of the Cold War, the ‘High North’ constituted a central theatre for military forces. Extensive NATO preparations were made, a solid infrastructure developed in northern Norway, and frequent and large-scale exercises were carried out. These developments, from the late 1970s, were much discussed by scholars and strategists. However, the change of perception, laying the foundation for the military build-up, had actually occurred a decade earlier, in the late 1960s. This change has not yet been given its rightful attention, partly because the relevant documents have only recently become available. This essay takes the chronology of events back into the 1960s and to NATO's secret discussions between the national Ministers of Defence and Chiefs of Staff. The most significant turning-points were the Flexible Response strategy of 1967; SACLANT's concern over increased Soviet naval activity and his ‘Maritime Strategy’ studies of 1965 and 1967; NATO's awakening to the Soviet SSBN threat in 1967; and the concept of ‘External Reinforcement of the Flanks’ of 1968 – finally followed by the ‘Brosio Study’ (named after the then NATO Secretary-General) of 1969. As a consequence of these developments NATO's ‘tactical northern flank’ was set to become an independent strategic theatre.