角度欺骗有源假目标的动力学特性

针对高空高速目标探测过程中可能出现的角度类欺骗有源假目标,从理论上系统地分析了其动力学性质,导出了假目标的动力学方程,并分析了假目标的机械能和动量矩守恒问题。理论分析和仿真试验均表明,具有固定角度欺骗的方位有源假目标其动力学特性和真实目标完全一致,在动力学上是无法鉴别真伪的;除此之外的其他角度类欺骗有源假目标均不满足高空高速目标椭圆轨道特性以及动力学守恒定律,利用这种差异可以在数据处理层对假目标进行鉴别。     

Markovian approximation for manufacturing systems of unreliable machines in tandem

This paper studies production planning of manufacturing systems of unreliable machines in tandem. The manufacturing system considered here produces one type of product. The demand is assumed to be a Poisson process and the processing time for one unit of product in each machine is exponentially distributed. A broken machine is subject to a sequence of repairing processes. The up time and the repairing time in each phase are assumed to be exponentially distributed. We study the manufacturing system by considering each machine as an individual system with stochastic supply and demand. The Markov Modulated Poisson Process (MMPP) is applied to model the process of supply. Numerical examples are given to demonstrate the accuracy of the proposed method. We employ (s, S) policy as production control. Fast algorithms are presented to solve the average running costs of the machine system for a given (s, S) policy and hence the approximated optimal (s, S) policy. © 2001 John Wiley & Sons, Inc. Naval Research Logistics 48: 65–78, 2001     

柔石《二月》:因着诚挚深入而丰富

柔石是“左联五烈士”中最具艺术潜质的作家。一般认为,他的代表作中篇小说《二月》纯熟地表现了青年知识者的追求,揭示了中国封建传统强大惯性重压下个人奋斗、人道主义理想的碰壁。但对于以主人公萧涧秋为代表的一代青年知识分子固有的人格缺失,以及由此造成的不必要的生存处境的尴尬、环境恶化,分析仍欠深人,因而遮蔽了《二月》这部作品主题意蕴应有的丰富性,也在客观上影响了对于柔石这位作家杰出艺术才能的认识。     

法国"海响尾蛇"导弹对付机动目标的能力估计

讨论“海响尾蛇”导弹在临近遭遇点时采用相对比例导航制导律对付机动目标的能力问题     

电偶腐蚀下非稳态扩散瞬时静电场分析

为分析在浓差极化条件下非稳态过程中的静电场分布情况,在斐克第二定律的基础上利用拉普拉斯变换求解电极表面氧浓度随时间的变化。通过法拉第定律分析受氧浓度控制下的电偶腐蚀电流密度,在此基础上利用电流元模型求解电解质溶液中任意位置处产生的瞬时电位及静电场强度,并通过实验验证结果的正确性。结果表明：浓差极化下的非稳态扩散传质产生的静电场及电位会随着时间的增加而逐渐减小,并最终达到稳态,且电流密度会随着氧的浓度减小而减小。     

Exact analysis of (R,s, S) inventory control systems with lost sales and zero lead time

We study an (R, s, S) inventory control policy with stochastic demand, lost sales, zero lead‐time and a target service level to be satisfied. The system is modeled as a discrete time Markov chain for which we present a novel approach to derive exact closed‐form solutions for the limiting distribution of the on‐hand inventory level at the end of a review period, given the reorder level (s) and order‐up‐to level (S). We then establish a relationship between the limiting distributions for adjacent values of the reorder point that is used in an efficient recursive algorithm to determine the optimal parameter values of the (R, s, S) replenishment policy. The algorithm is easy to implement and entails less effort than solving the steady‐state equations for the corresponding Markov model. Point‐of‐use hospital inventory systems share the essential characteristics of the inventory system we model, and a case study using real data from such a system shows that with our approach, optimal policies with significant savings in inventory management effort are easily obtained for a large family of items.     

基于扩展比例导引律的制导模型

针对常用比例导弹导引律制导命中率低的问题,分析了比例导引律、偏置比例导引律、修正比例导引律的制导性能,提出了一种基于扩展比例导引律的制导模型,经仿真表明,该导引律具有目标垂直和水平机动跟踪能力,提升了反导作战的机动能力和效率。     

便携式自寻的反坦克导弹攻顶弹道研究

便携式反坦克导弹在通过击顶方式打击目标时,要同时满足落角和精度的要求,以达到对目标的毁伤效能。首先推导带落角约束的最优比例导引律;然后设计携式反坦克导弹击顶弹道方案,导弹先出筒无控,以指数规律完成爬升,采用定攻角进行滑翔飞行,弹道末端运用推导的导引律来满足对落点和落角的约束。仿真结果表明,当反坦克导弹攻击不同距离的目标时,该弹道方案具有较强的有效性。     

多约束下的高超声速飞行器三维非线性自适应末制导律

面向多约束下高超声速飞行器末制导过程中的通道耦合、参数扰动、模型失配等突出问题,设计一种适于高超声速飞行器的三维非线性自适应末制导律。为了模型描述的完整性和简洁性,引入视线旋量和旋量速度的概念,并基于此建立三维制导参考模型和实际系统的表达式;为了保证制导律的鲁棒性和自适应性,基于自适应控制理论,设计一种三维非线性自适应制导律;通过数学推导证明了该制导律的稳定性。该制导律能够从理论上克服高超声速飞行器末制导面临的通道耦合、参数扰动、模型失配等突出问题,满足多约束制导要求。仿真结果验证了所设计制导律的有效性。     

基于偏差熵的专家聚类赋权方法

在群决策专家聚类赋权过程中,可能出现专家给出的判断矩阵一致性比率与排序向量信息熵都相等但专家意见不同,却被赋予了相同权重的情况。针对上述问题,提出一种基于偏差熵的专家聚类赋权方法。该方法采用聚类分析的思想,基于比例构建相似系数,实现对专家群的分类;引入专家判断矩阵的一致性权重,并综合类容量构建权重指标来反映类别间的差异,确定专家类间权重;最后,在各专家类中建立偏差熵模型,依据类中专家达成一致性意见的贡献程度确定专家的类内权重,并得到专家的总体权重。具体算例表明,该方法可行有效。