尾流自导鱼雷带角射击弹道仿真

为简化指控系统解算流程,缩短指控系统解算尾流自导鱼雷带角射击参数时间,为后续的鱼雷模拟器的软件研制提供实现手段,提出在尾流自导鱼雷有利提前角射击弹道的基础上进行二次转角航行的改进的尾流自导鱼雷带角射击模型。依据尾流自导鱼雷射击原理,结合有利提前角射击和二次转角射击,对所提出的模型及其约束条件进行了分析与推导,简化了鱼雷带角射击参数的解算。深入分析了尾流自导鱼雷带角射击逻辑,提出采用面向过程设计方法对模型进行仿真,经过对仿真输出图形和仿真数据的分析,验证了所提出模型的准确性。     

The Impact of the Unemployment Rate on Attrition of First-Term Enlistees

This study examines the effects of home-state unemployment rates on attrition behavior of Navy enlistees for successive career windows during the first term of service: the first 6?months, the second 6?months, the second year, and the third year of service. The results indicate that attrition is negatively associated with changes in the local unemployment rate during the first three career windows covering two years of service. However, after two years of service, the estimated effect of the unemployment rate becomes insignificant for most groups of sailors. This is likely because sailors with the poorest job matches are sorted out early in the first term of service.     

双源连续波对引信的辐照效应研究

为研究复杂电磁环境对某引信的影响,从双源连续波入手,运用双源连续波对工作状态某引信辐照的实验方法进行实验.实验结果表明,在以引信工作频率为中心的150MHz频率范围内对加电引信进行双源连续波辐照实验可使引信发火,辐照结束后引信工作正常,实验的重复性较好.两连续波频率间隔不同,可使引信发火的场强组合数值大小不相同,实验中当两连续波远离引信工作频率且频差10MHz以上时,发火场强组合近似呈线性.最后对双源连续波对引信的辐照效应机理作了分析,两连续波频率间隔不同,引信发火机理不同.     

静电放电对微机接口电路干扰效应研究

为研究静电放电(ESD)对微机接口电路的干扰效应,设计了一种单片机系统串行数据传输电路试验模型。利用静电放电模拟器对自行设计的单片机系统进行了效应试验,并对测得的试验数据进行了分析,得出了这类典型串口通讯在静电放电环境下的一些规律。     

城镇化与农民增收的相关性分析

从理论上分析,城镇化与农民增收之间存在很强的正相关关系;而现实中,在政策措施不科学的情况下,城镇化为农民增收带来了很大的负面效应。因而必须采取必要措施消除负面影响,充分体现城镇化对农民增收的正相关效应。     

声尾流自导鱼雷导引策略仿真与优化

在分析尾流几何模型及其气泡分布密度的规律的基础上,首先建立了较贴近实际的尾流声学仿真模型。其次,按照尾流自导检测流程,基于反射系数推导了尾流层及海面气泡层的回声级模型,由此建立了鱼雷声学自导检测模型。随后,根据研究需要设计了基于鱼雷作战使用评估理论的声尾流自导鱼雷仿真系统,该系统能够真实模拟尾流自导系统工作过程及鱼雷水下运动过程。最后,以该仿真系统为依托,实现了声尾流自导鱼雷应对空穴或断层的修正导引策略的仿真优化。应用结果表明:该研究对于尾流自导鱼雷导引策略优化和尾流自导仿真方法研究具有实际应用价值。     

Shaped charge penetration into high- and ultrahigh-strength Steel–Fiber reactive powder concrete targets

Experiments on shaped charge penetration into high and ultrahigh strength steel-fiber reactive powder concrete (RPC) targets were performed in this paper. Results show that the variation of penetration depth and crater diameter with concrete strength is different from that of shaped charge penetration into normal strength concrete (NSC). The crater diameter of RPC is smaller than that of NSC penetrated by the shaped charge. The jet particles are strongly disturbed and hardly reach the crater bottom because they pass through the narrow channel formed by jet penetration into the RPC. The effects of radial drift velocity and gap effects of jet particles for a shaped charge penetration into RPC target are discussed. Moreover, a theoretical model is presented to describe the penetration of shaped charge into RPC target. As the concrete strength increases, the penetration resistance increases and the entrance crater diameter decreases. Given the drift velocity and narrow crater channel, the low-velocity jet particles can hardly reach the crater bottom to increase the penetration depth. Moreover, the narrow channel has a stronger interference to the jet particles with increasing concrete strength; hence, the gap effects must be considered. The drift velocity and gap effects, which are the same as penetration resistance, also have significant effects during the process of shaped charge penetration into ultrahigh-strength concrete. The crater profiles are calculated through a theoretical model, and the results are in good agreement with the experiments.     

三种艉部附体方案的粘性阻力数值计算

水面船舶艉部附体不但影响船舶的阻力,而且对螺旋桨的伴流分数以及推力减额也会产生较大影响。近年来,越来越多的研究者都重视使用数值方法进行船舶附体优化设计。在分析某排水型水面船舶艉部附体特点以及优化目标后,设计出两套艉部附体优化方案。通过数值计算方法对这3种方案的船体带附体模型在不同雷诺数条件下进行三维粘性流场的数值模拟。分析比较了它们的粘性阻力和螺旋桨桨盘面处的伴流,最后得到双尾鳍附件的最优方案。     

基于镜像延拓和神经网络的EMD端点效应改进方法

经验模态分解(Empirical Mode Decomposition,EMD)在机械故障诊断中存在一个比较严重的问题,即端点效应。镜像延拓是克服端点效应的有效方法,采用镜像延拓处理端点效应时,要求将镜面放置在局部极值点处,针对这一问题,提出了一种基于镜像延拓和神经网络相结合的数据延拓方法。采用神经网络预测原信号序列,将信号向前向后各延拓一个极值点,再采用镜像延拓有效地减小EMD分解中的端点效应。通过对仿真信号的分析,验证了该方法能有效抑制EMD方法中的端点效应问题。     

自适应均衡器非维纳效应的仿真研究

窄带干扰条件下,自适应滤波器产生非维纳效应。在分析非维纳效应产生机理的基础上,详细仿真研究了强单音干扰条件下,自适应均衡器的收敛和跟踪性能。通过研究得出了一些新的结论:多径和干扰的功率严重影响自适应均衡器的收敛速度,而干扰的频率对收敛速度几乎没有影响;固定的强单音干扰对自适应滤波器的信道跟踪性能影响较小;慢变的强单音干扰对跟踪性能影响较小,快变的单音干扰将对跟踪性能造成严重影响。