Bounding the optimal burn‐in time for a system with two types of failure

Burn‐in is a widely used method to improve the quality of products or systems after they have been produced. In this paper, we consider the problem of determining bounds to the optimal burn‐in time and optimal replacement policy maximizing the steady state availability of a repairable system. It is assumed that two types of system failures may occur: One is Type I failure (minor failure), which can be removed by a minimal repair, and the other is Type II failure (catastrophic failure), which can be removed only by a complete repair. Assuming that the underlying lifetime distribution of the system has a bathtub‐shaped failure rate function, upper and lower bounds for the optimal burn‐in time are provided. Furthermore, some other applications of optimal burn‐in are also considered. © 2004 Wiley Periodicals, Inc. Naval Research Logistics, 2004     

单极化圆台相控阵天线的空域极化特性

针对水平或垂直极化偶极子激励的单极化圆台相控阵天线,建立了其电扫描时空域极化特性的数学模型.理论分析和仿真结果表明单极化圆台相控阵天线的空域极化比随观测角偏离法线方向的角度单调递增,随斜面倾角增大而单调递减.同时,圆台相控阵天线的方向图与阵元极化方式、波束指向角以及观测角有关.圆台阵面规模越大,方向图和空域极化变化越丰富.以上结论为基于圆台相控阵天线空域极化特性的极化散射矩阵测量、极化滤波和抗干扰等研究提供了理论依据,为全极化圆台相控阵天线设计、极化特性分析和极化校准等研究奠定了理论基础.     

Simulation on the dynamic stability derivatives of battle-structure-damaged aircrafts

Accurately evaluating the aerodynamic performance of a battle-structure-damaged aircraft is essential to enable the pilot to optimize the flight control strategy. Based on CFD and rigid dynamic mesh techniques, a numerical method is developed to calculate the longitudinal and longitudinal-lateral coupling forces and moments with small amplitude sinusoidal pitch oscillation, and the corresponding dynamic de-rivatives of two fragment-structure-damaged and two continuous-rod-damaged models modified from the SACCON UAV. The results indicate that, at the reference point set in this paper, additional positive damping is generated in fragment-damaged configurations; thus, the absolute values of the negative pitch dynamic derivative increase. The missing wingtip induces negative pitch damping on the aircraft and decreases the value of the pitch dynamic derivative. The missing middle wing causes a noticeable increase in the absolute value of the pitch dynamic derivative;the missing parts on the right wing cause the aircraft to roll to the right side in the dynamic process, and the pitch-roll coupling cross dynamic derivatives are positive. Moreover, the values of these derivatives increase as the damaged area on the right wing increases, and an optimal case with the smallest cross dynamic derivative can be found to help improve the survivability of damaged aircraft.     

某型导弹地面制导站静态参数自动测试系统

介绍了以LabWindows/CVI为软件开发平台,基于PCI和ISA总线的某型导弹自动测试系统的总体方案,给出了系统硬件和软件的具体设计方法,分析了信号转接电路和ISA总线接口电路的设计原理,阐述了组合测试模块、故障诊断模块和数据库管理模块的实现方法。经部队实际测试表明,该系统能够可靠、出色地完成该型导弹地面指导站测试和故障诊断的任务,实现模块化高效智能自动测试。     

试论郑和下西洋的军事贡献--纪念郑和下西洋600周年

15世纪初的郑和下西洋,是军事史上一个意义重大的事件.当前学术界多从郑和下西洋的政治、经济、文化、外交、航海等方面研究其贡献,鲜少从军事角度进行阐述.本文从郑和下西洋坚持维护和平、反对霸权的军事原则,确立经略海洋、"以海屏陆"的军事战略,展现恩威并施、灵活多样的军事艺术等三个方面集中论述了郑和下西洋在军事上的贡献,揭示了郑和下西洋在军事史上的重大意义,从一个侧面反映出郑和不仅是一位和平使者,而且是一位具有政治远见、运筹帷幄的军事家.     

分布式导弹发射控制系统设计模型

分布式导弹发射控制系统是以多微机结构处理导弹发射控制过程的一种控制系统,是当代导弹武器发射控制系统所广泛采用的一种先进技术。通过对某类常规战术导弹实施分布式发射控制模型设计的分析,探讨了分布式微机结构在军事控制领域的应用前景     

关于运动副耐磨可靠性方程的几点讨论

对运动副的耐磨可靠性方程进行了较深入的讨论,从而可定量的计算产品无故障工作概率或可靠度以及给定允许故障概率下的安全系数.揭示了传统设计中采用安全系数作为衡量产品的工作能力的方法所存在的弊病.     

Limiting behavior of mixtures of discrete lifetime distributions

In this article a mixture of discrete lifetime distributions is considered. Sufficient conditions are given for establishing results on the limiting behavior of the failure rate of the mixture. A connection between this limiting behavior and burn in is shown. The limiting behavior of the mean residual life of the mixture is also considered. The mixed Poisson, geometric, negative binomial, and Weibull distributions are discussed. © 1996 John Wiley & Sons, Inc.     

军队编制体制调整对人员整体结构的影响

建立了军队人员等级结构模型,通过"等待时间"和"理想态"的定义,给出了从任意等级状态达到"理想态"的最优方法。在给定理想态下,为平衡等级结构内部流动性和平稳性,提出了求取各等级转移概率(转移矩阵)的方法。利用该模型,以"等待时间"和调入量为指标,对军队体制编制调整中出现的结构不平衡的现象进行分析,提出了对策建议。     

构件和运动副的工作能力的定量描述

继建立起机构工作能力的计算模型之后,讨论如何将构件和运动副的工作能力定量化,并给出了计算示例,从而使机构工作能力的定量分析更为明了.