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Li-zhi Xu Cheng-xin Du Chun Cheng Xiao-dong Wang Jiang-bo Wang Zhong-hua Du Guang-fa Gao 《防务技术》2021,17(3):859-873
When a penetrator with enhanced lateral effect (PELE) impacts on a reinforced concrete (RC) target, the target is damaged with a large opening. An understanding of how PELE projectile parameters affect the opening dimension, is essential for effective design of the PELE projectile. In this study, under the condition that the impact velocity and target parameters (strength and thickness) were fixed values, the important influence factors of the PELE (jacket wall thickness B, jacket material strength Y1, filling material strength Y2 and angle of monolithic jacketθ) were determined by a dimensional analysis. Tests and simulations of the PELE penetrating the RC target were conducted to analyze the influence of these factors on opening diameter ((D), an equivalent diameter under relative kinetic energy). Based on the test and simulation results, it is found that the influence of these factors B, Y1 andθon the deformation mode of the jacket shows a similar trend:as values of the three factors decrease, the jacket deforms from small bending deformation to large one, and then to curling deformation. This causes the opening diameter to first increase with the decrease of these three factors, and then decreases. It is well known that the bending resistance of the jacket is related to these factors B, Y1 andθ. Therefore, a plastic limit bending moment (M0) of the jacket was quoted to characterize the influence of these factors on the bending deformation of the jacket and the opening diameter of the target. The influence factor Y2 causes (D) to first increase with the increase of Y2, and then decreases. A formula was developed to predict the opening diameter, whose influence parameters were considered in a dimensionless way. It has been shown that the dimensionless opening diameter (D)/d1 is dependent on two dimensionless parameters Q = (d31fc/M0) and G = (fc/Y2), where d1 and fc are the outer diameter of the projectile and the compressive strength of the target, respectively. 相似文献
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针对现有频域近似熵频谱感知技术在低信噪比条件下抗噪声性能和检测性能有待提升的问题,提出了一种基于LMD频域近似熵的频谱感知算法。(1)算法筛选出3个PF分量累加求和,使得算法提取局部调频包络特征信息得到最优,进一步排除噪声不确定度的影响。(2)算法对累加PF分量进行频域变换后求其近似熵,增强算法对频域信息的嗅探能力,提升算法检测性能。Monte Carlo仿真结果表明,在噪声不确定度为0dB,采样点数为8 000的情况下,当信噪比大于-19 d B时,可以对2ASK信号达到100%的检测概率,与现有频域近似熵算法相比,检测性能约有17 d B的提升。 相似文献
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针对容忍延迟网络(DTN)高延迟、数据传输成功率低等问题,提出了一种基于节点综合效能的DTN路由算法SERA。该算法综合考虑移动节点的活跃度和剩余能量,使消息副本向综合效能高的节点扩散。SERA节点活跃度描述了节点的社会和动态特性,SERA尽量将消息副本传递给活跃度高的节点,以提高消息传输的成功率;在选择中继节点时,充分考虑节点的能量状态,以避免能量不足的节点承担更多的信息传输任务,从而提高网络节点的存活率。仿真结果表明,与典型的DTN路由算法相比,SERA能够更好地平衡节点的能耗,获得更高的消息递交成功率和更长的网络生存期。 相似文献
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针对行均值法用于海天背景下舰船目标区域定位可靠性不高、容易受到舰船目标大小和海天背景复杂程度影响的不足,提出一种基于图像行灰度熵的舰船目标区域定位方法。该方法在分析海天背景下舰船目标可见光图像成像特点基础上,结合信息熵理论给出了图像灰度熵及行灰度熵的概念,利用图像行灰度熵描述图像在行方向上的灰度变化程度,选用滑动区间方差搜索策略得到图像行灰度熵曲线的突变区间,从而实现舰船目标区域定位,最后通过实际图像进行了实验验证。实验结果表明,该方法能对舰船目标所在区域有效定位,其准确性及鲁棒性均优于行均值法。 相似文献
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铝合金板材相对均匀性的声-超声评价研究 总被引:1,自引:0,他引:1
基于Ritec-SNAP系统建立了声-超声技术实验系统,阐述了该实验系统的原理及应力波因子的定义,分析了在声-超声技术评价过程中用声信号的幅频特性及应力波因子表征材料相对均匀性的可行性。利用建立起来的实验系统,对铝板的相对均匀性进行了声-超声评价的实验研究。实验结果表明,用应力波因子评价铝合金板材的相对均匀性具有可行性。 相似文献
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