Estimating component characteristics from system failure‐time data

Suppose that failure times are available from a random sample of N systems of a given, fixed design with components which have i.i.d. lifetimes distributed according to a common distribution F. The inverse problem of estimating F from data on observed system lifetimes is considered. Using the known relationship between the system and component lifetime distributions via signature and domination theory, the nonparametric maximum likelihood estimator _N(t) of the component survival function (t) is identified and shown to be accessible numerically in any application of interest. The asymptotic distribution of _N(t) is also identified, facilitating the construction of approximate confidence intervals for (t) for N sufficiently large. Simulation results for samples of size N = 50 and N = 100 for a collection of five parametric lifetime models demonstrate the utility of the recommended estimator. Possible extensions beyond the i.i.d. framework are discussed in the concluding section. © 2010 Wiley Periodicals, Inc. Naval Research Logistics, 2010     

具有时滞和扩散的动力系统的全局稳定性

研究一类具有时滞和扩散的非自治Ⅲ类功能性反应系统,给出了系统一致持久和全局渐近稳定的充分条件。     

一类广义L-统计量的极限分布

假定(X1,Y1),(X2,Y2),…,(Xn,Yn)是取自二维随机向量(X,Y)的独立同分布样本.记X(1)≤X(2)≤…≤X(n)是X1,X2,…,Xn产生的次序统计量,Y[1],Y[2],…,Y[n]是诱导的次序统计量.讨论广义L-统计量Tn=n-1 n∑i=1 J(i/n+1)Y[i]的极限分布,式中J(x)是由实际问题的需要而选取的权函数.在较弱的条件下,证明了Tn的渐近正态性,同时给出了Tn的期望和方差的渐近公式.     

多类传感器航迹参数关联研究

采用层次型数据融合结构,研究了防空作战(AAW)系统中多类传感器航迹相关问题。首先对目标航迹的真实跟踪概率(TTP)进行了讨论,在两个模型假设的基础上给出了TTP的计算公式。提出利用渐近分析理论研究多类传感器相关参数及其在时间域上参数方程的航迹参数关联问题。在此基础上设计了多类传感器系统中上层处理节点航迹相关算法。     

无线网络控制系统一致性研究

通过构建李雅普诺夫函数,对具有不同拓扑结构的无线网络控制系统的一致性问题进行了研究。利用网络结构的邻接矩阵对网络拓扑结构进行描述,同时构造系统的延迟矩阵,结合复杂网络理论中的聚类系数、耦合强度的概念,对系统进行建模。针对复杂网络中常用的两种结构,构建不同的邻接矩阵和延迟矩阵,利用线性矩阵不等式的方法,给出使系统稳定的一般性条件。最后仿真结果验证了方法的有效性。     

分布式态势感知一致性分析与度量方法研究

一致的态势感知,是现代武器、火力系统以及部队紧耦合协同作战的基础。本文以分布式态势感知理论为依据,从系统的角度,构建了团队达成一致态势感知过程的动力学模型;以系统内部一致性、外部一致性和一致所需最短时间为指标,给出了团队态势感知一致性的度量方法。仿真结果表明,适当地提高团队内沟通的广泛度和相互作用强度,选择合适的沟通网络,对提高一致性能力有积极的作用。     

无人飞行器Ad Hoc网络中容错节点移动控制算法

针对无人飞行器Ad Hoc网络的容错设计需求,基于UAV节点的可控移动特性,提出了一种基于强化边启发的节点移动控制算法.首先采用文化基因算法对给定通信网络对应的拓扑图进行搜索,求解使图获取顶点2 -连通属性所需新增的最小成本强化边组合.以强化边为启发,将连接的节点移动到彼此通信范围内来实现强化边,同时以这些节点为leader,采用基于一致性算法的leader-follower控制算法移动其他关联节点,使变化后的网络为顶点2-连通,从而实现网络容错.仿真实验结果表明算法的可行性与有效性,节点总的移动距离少于用于对比的块移动算法和紧缩算法.     

战争设计工程中专家思维收敛过程的建模与分析

专家意见能否达成共识是战争设计工程中的一个关键问题.首先从复杂理论视角对专家思维过程的适应性、聚集性、非线性进行分析,接着将专家群体划分为两类并且运用马尔科夫转移矩阵对研讨过程建模,提出并证明了两类专家群体思维收敛的充分必要条件,得到群体思维收敛不仅与研讨过程中专家之间的关系影响矩阵有关,而且与专家的初始意见有关.最后通过计算机仿真进一步探索了群体思维收敛过程的影响因素.     

Parametric inference for component distributions from lifetimes of systems with dependent components

In system reliability analysis, for an n ‐component system, the estimation of the performance of the components in the system is not straightforward in practice, especially when the components are dependent. Here, by assuming the n components in the system to be identically distributed with a common distribution belonging to a scale‐family and the dependence structure between the components being known, we discuss the estimation of the lifetime distributions of the components in the system based on the lifetimes of systems with the same structure. We develop a general framework for inference on the scale parameter of the component lifetime distribution. Specifically, the method of moments estimator (MME) and the maximum likelihood estimator (MLE) are derived for the scale parameter, and the conditions for the existence of the MLE are also discussed. The asymptotic confidence intervals for the scale parameter are also developed based on the MME and the MLE. General simulation procedures for the system lifetime under this model are described. Finally, some examples of two‐ and three‐component systems are presented to illustrate all the inferential procedures developed here. © 2012 Wiley Periodicals, Inc. Naval Research Logistics, 2012     

考虑Reissner效应的功能梯度柱壳裂纹高阶渐近场

针对考虑Reissner效应的功能梯度柱壳裂纹问题,通过分离变量和级数展开法构造广义位移函数,求得了裂纹尖端高阶渐近场。结果表明：该解类似于Williams解,为此类问题的特征函数,能够描述此类材料各种含裂纹结构的整个应力场和位移场;材料非均匀性对高阶项有显著影响。