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311.
影响舰载雷达探测误差主要为平台导航定位误差和传感器自身探测误差,针对对这两类误差的影响因素进行了分析,首次综合考虑这两种系统误差,提出了一种基于正则化的多平台导航定位及探测偏差估计方法,利用不同舰艇上传感器对公共目标探测的迭合条件,建立系统误差观测方程,利用LS对两种系统误差同时进行了估计,并在偏差估计中采用正则化估计方法,提高估计结果的稳定性,最后进行了仿真验证,仿真效果验证了算法的有效性,具有较高的工程应用价值. 相似文献
312.
When considering the bomb explosion damage effect, the air shock wave and high-speed fragments of the bomb case are two major threats. In experiments, the air shock wave was studied by the bare ex-plosives superseding the real cased bomb; in contrast, the bomb case influence was ignored to reduce risk. The air explosion simulations of the MK84 warhead with and without the case were conducted. The numerical simulation results showed that the bomb case significantly influenced the shock wave generated by the bomb: the spatial distribution of shock wave in the near field changed, and the peak value of shock wave was reduced. Breakage of the case and kinetic energy of the fragmentation consumed 3 and 38% of the explosion energy, respectively. The increasing factors of the peak over-pressure induced by the bare explosive on the ground and in the air were 1.43-3.04 and 1.37-1.57, respectively. Four typical stages of case breakage were defined. The mass distribution of the fragments follows the Mott distribution. The initial velocity distribution of the fragments agreed well with the Gurney equation. 相似文献
313.
This paper studies the friction stir spot welding of AA2024-T3/AA7075-T6 Al alloys in the ambient and underwater environments by clarifying the nugget features,microstructure,fracture and mechanical properties of the joints.The results show that the water-cooling medium exhibits a significant heat absorption capacity in the AA2024-T3/AA7075-T6 welded joint.Nugget features such as stir zone width,circular imprints,average grain sizes,and angular inter-material hooking are reduced by the water-cooling effect in the joints.Narrower whitish(intercalated structures)bands are formed in the under-water joints while Mg2Si and Al2CuMg precipitates are formed in the ambient and the underwater welded joints respectively.An increase in tool rotational speed(600-1400 rpm)and plunge depth(0.1-0.5 mm)increases the tensile-shear force of the welded AA2024-T3/AA7075-T6 joints in both the ambient and underwater environments.The maximum tensile-shear forces of 5900 N and 6700 N were obtained in the ambient and the underwater welds respectively. 相似文献
314.
采取实验和数值模拟相结合的方法对激光辐照45#钢板的响应特性进行研究。基于连续光纤激光发射系统,开展钢板的激光辐照实验,得到温度场分布及靶板的烧蚀穿孔特性;基于ANSYS建立靶板有限元模型,模拟激光辐照下靶板的热响应过程,得到了靶板厚度、激光功率和光斑直径等因素对靶板温度分布及靶板穿孔特性的影响规律。 相似文献