坦克动力舱空气流动与传热影响因素的仿真研究

以k-ε两方程湍流模型和非结构化网格为基础,利用FLUENT软件针对某型主战坦克动力舱内的空气流场和温度场进行了三维数值仿真计算与分析,得出了环境温度、压力和坦克行驶速度等因素对动力舱内的空气流动和传热的影响关系.     

装甲装备人机界面因素对乘员可靠性的影响分析

装甲装备乘员可靠性受内部因素和外部因素的共同影响,而人机界面是外部因素的主要组成部分.通过进行装甲装备人机界面特性分析,确定了乘员可靠性的人机界面影响因素,并结合人的失误致因分析,通过对装备使用者进行问卷调查的形式对其进行了验证.得出的结论对于装备改造和部队乘员选拔都有一定的指导意义.     

双向受载裂纹板的碳纤维复合材料补片的胶接修补分析

建立了碳纤维复合材料补片胶接修补双向受载裂纹板的3D有限元模型,分析了补片的单面胶接修补效果,探讨了补片材料、铺层顺序、补片长度及载荷比等对裂纹应力强度因子的影响规律。结果表明:复合材料补片的存在使裂纹板垂直裂纹方向载荷和平行裂纹板方向载荷发生耦合作用,从而影响补片修补效果。平行裂纹方向的压应力可降低裂纹尖端的应力集中因子,而拉应力可提高裂纹尖端的应力集中因子。     

火灾现场勘验中危险因素探究

火灾现场勘验中存在多种危险因素,严重威胁着勘验人员的人身安全。对倒塌、烟气和触电等火灾现场中几种常见的危险因素,在深入分析其形成机理和危害特征的基础上,有针对性地提出了各种危险因素的预防措施。     

四步法清洗深度污染陶瓷微滤膜实验研究

对深度污染0.2 μm Al2O3陶瓷微滤膜表面和截面进行高分辨扫描电镜观测,在初步实验基础上提出一种有效的污染膜组合清洗方案:第1步,纯水漂洗;第2步,用氢氧化钠与次氯酸钠混合溶液(质量分数为1%)正向循环清洗;第3步,用柠檬酸溶液(质量分数为1%)正向循环清洗;第4步,用二氧化氯溶液(质量分数为0.12%)正向循环...     

Data‐driven variation source identification for manufacturing process using the eigenspace comparison method

Variation reduction of manufacturing processes is an essential objective of process quality improvement. It is highly desirable to develop a methodology of variation source identification that helps quickly identify the variation sources, hence leading to quality improvement and cost reduction in manufacturing systems. This paper presents a variation source identification method based on the analysis of the covariance matrix of process quality measurements. The identification procedure utilizes the fact that the eigenspace of the quality measurement covariance matrix can be decomposed into a subspace due to variation sources and a subspace purely due to system noise. The former subspaces for different samples will be the same if the same variation sources dominate. A testing procedure is presented, which can determine the closeness of the subspaces under sampling uncertainty. A case study is conducted to illustrate the effectiveness of this methodology. © 2006 Wiley Periodicals, Inc. Naval Research Logistics, 2006.     

基于ICA的多姿态人脸表示

将独立成分分析(ICA)应用于多姿态人脸识别。对比分析了ICA和主成分分析(PCA)两种人脸识别方法的差异,并重点研究了多姿态人脸的独立成分(IC)表示。在基于权向量幅值的方法基础上,引入了基于比例因子的IC核选择的新方法。实验表明,新方法有利于提高识别的准确率和识别的效率。     

基于改进差分进化算法的内弹道参数优化

火炮内弹道参数直接影响其计算结果,内弹道参数优化设计是内弹道分析计算的重要环节。基于经典内弹道计算模型,以火药内弹道计算中最为敏感的燃速指数及其燃速系数为设计参量,以最大膛压及弹丸初速的计算值与测试值一致性为目标,对差分进化算法群体的初始化、变异因子及变异模式进行了改进,对某型火炮的内弹道参数进行了优化计算。优化设计结果表明改进后的差分进化算法满足内弹道设计工程实践要求,为内弹道参数优化设计提供了一种有效的算法。     

Adaptive fault-tolerant control based on boundary estimation for space robot under joint actuator faults and uncertain parameters

Since the joint actuator of the space robot executes the control instructions frequently in the harsh space environment, it is prone to the partial loss of control effectiveness (PLCE) fault. An adaptive fault-tolerant control algorithm is designed for a space robot system with the uncertain parameters and the PLCE actuator faults. The mathematical model of the system is established based on the Lagrange method, and the PLCE actuator fault is described as an effectiveness factor. The lower bound of the effectiveness factors and the upper bound of the uncertain parameters are estimated by an adaptive strategy, and the estimated value is fed back to the control algorithm. Compared with the traditional fault-tolerant algorithms, the proposed algorithm does not need to predetermine the lower bound of the effectiveness factor, hence it is more in line with the actual engineering application. It is proved that the algorithm can guarantee the stability of the closed-loop system based on the Lyapunov function method. The numerical simulation results show that the proposed algorithm can not only compensate for the uncertain parameters, but also can tolerate the PLCE actuator faults effectively, which verifies the effectiveness and superiority of the control scheme.     

高原环境对弹丸动态稳定性的影响

分析了高原环境低空气密度对弹丸动态稳定性的影响。给出了弹道坐标系中的力方程组和非滚转弹体坐标系中的力矩方程组,并通过线性化方法得到弹丸角运动的状态空间模型。列出了角运动状态矩阵的四个特征根,并利用复数平方根计算方法得到特征根实部的表达式。提出弹丸动态稳定性稳定因子的新定义,并证明新的动态稳定条件与传统的动态稳定条件是一致的。讨论了低空气密度对尾翼稳定弹和旋转稳定弹动态稳定性的影响,并通过仿真说明弹丸在高原条件和平原条件下的动态稳定性存在差异。