脉冲等离子体推力器工作过程一维磁流体动力学数值模拟

通过耦合脉冲等离子体推力器(PPT)工作过程中电场、磁场、流场之间的相互作用,描述了电容器放电、推进剂烧蚀、等离子体加速流动等过程,建立了基于磁流体动力学(MHD)的一维非定常数学模型,对PPT的工作过程进行数值模拟。对数值模拟结果作了相应分析,并将部分模拟结果与实验数据进行了比较。结果表明,模型正确反映了推力器放电过程、推进剂烧蚀质量与表面温度的变化趋势。     

PCP系统的优化对船舶水下电场的抑制作用

为了达到抑制水下电场特征的目的,需要使船身电位保持均匀.采用边界元法建立了空气-海水两层介质中的船体模型,通过改变牺牲阳极阴极保护系统中牺牲阳极的数量和分布,定量计算了不同保护状态下的船身电位和水下电场,并进行了实验室船模实验.仿真和实验结果均表明:对阴极保护系统进行合理的设计,使阳极与腐蚀区域之间保护电流的作用距离缩...     

A bivariate optimal replacement policy for a cold standby repairable system with repair priority

In this article, an optimal replacement policy for a cold standby repairable system consisting of two dissimilar components with repair priority is studied. Assume that both Components 1 and 2, after repair, are not as good as new, and the main component (Component 1) has repair priority. Both the sequence of working times and that of the components'repair times are generated by geometric processes. We consider a bivariate replacement policy (T,N) in which the system is replaced when either cumulative working time of Component 1 reaches T, or the number of failures of Component 1 reaches N, whichever occurs first. The problem is to determine the optimal replacement policy (T,N)* such that the long run average loss per unit time (or simply the average loss rate) of the system is minimized. An explicit expression of this rate is derived, and then optimal policy (T,N)* can be numerically determined through a two‐dimensional‐search procedure. A numerical example is given to illustrate the model's applicability and procedure, and to illustrate some properties of the optimal solution. We also show that if replacements are made solely on the basis of the number of failures N, or solely on the basis of the cumulative working time T, the former class of policies performs better than the latter, albeit only under some mild conditions. © 2010 Wiley Periodicals, Inc. Naval Research Logistics, 2010     

俄罗斯军事人才生成机制对武警视级指挥院校任职教育的启示

俄罗斯军事教育注重培养学员的国家意识,强调教员必须具有很强的综合能力,教学方法灵活、实用,考试方法突出能力素质的考核。俄罗斯军事人才培养形成了注重实战演练、坚持岗位轮换、引进竞争机制、重视鉴定考核的良性机制,保证了人才培养的质量。武警部队初级指挥院校提高任职教育质量应借鉴俄罗斯军事人才培养方法,在培训内容、教员选拔、授课方法、考试形式等方面进行改革。     

灰色预测模型在非致命武器经济寿命预测中的应用

针对目前非致命武器经济寿命方面的研究相当缺乏的现状,结合非致命武器的自身特点,在全面分析装备全寿命周期费用的基础上,引入灰色理论,运用GM（1,1）模型对非致命武器的经济寿命周期费用进行估算和预测。通过分析,灰色预测模型具有较高的建模精度,预测方法和结果对非致命武器的经济寿命预测具有很强的实用性。     

超音速等离子喷涂连续梯度热障涂层工艺优化研究

采用"双通道、双温区"超音速等离子喷涂工艺制备了Ce-YSZ/NiCoCrAlY连续梯度热障涂层(CG-TBCs)。借助热喷涂粒子状态在线监测系统Spraywatch-2i,分别研究了电弧功率、喷涂距离对Ce-YSZ/NiCoCrAlY粒子速度和温度的影响。实验结果表明,当电弧功率为70 kW和68 kW时,Ce-YSZ与NiCoCrAlY粒子速度达到最高,分别为620 m/s和430 m/s。Ce-YSZ和NiCoCrAlY粉末粒子的平均温度均随电弧功率的增加而上升,但当功率分别达到60 kW和65 kW时,粒子温度的上升趋势不再明显。电弧功率选择在68 kW,喷涂距离定为90 mm左右时,制备的CG-TBCs在经历100次热循环后,其表面和内部均未出现明显的裂纹,具有优异的热震性能。     

任务空间概念模型VV&A研究

任务空间概念模型是现实世界军事知识的第一层抽象,是仿真系统开发的业务基础。所以任务空间概念模型的质量直接影响到仿真系统的质量,任务空间概念模型自身的VV&A是一个非常值得关注的问题。任务空间概念建模本质上看是军事领域的知识表示或者需求描述,定性描述占主要,定量成分非常少。因此,传统的通过分析输出数据的方法不能适应任务空间概念模型的特点。概要介绍了任务空间概念模型建模,并且提出了从专家法、静态校核机制、概念执行机制三个角度来考察模型质量的思路。     

云模型及其在指挥控制系统可靠性分析中的应用

根据指挥控制系统的特点及作战应用的具体情况,从指挥控制系统的可靠性出发,提出了适合指控系统可靠性分析的云模型。通过拟定性能评价指标,导出各指标的云模型及其多维加权综合云的重心,应用云重心评价方法进行分析;并通过案例,运用基于PC-L INM AP的云重心评价方法,以影响指挥控制系统可靠性的两个重要性能指标为依据,分析了未来联合作战中指挥控制系统的可靠性,比较贴近作战实际,可信度较高。     

Optimal pricing and inventory control policy in periodic‐review systems with fixed ordering cost and lost sales

This paper studies a periodic‐review pricing and inventory control problem for a retailer, which faces stochastic price‐sensitive demand, under quite general modeling assumptions. Any unsatisfied demand is lost, and any leftover inventory at the end of the finite selling horizon has a salvage value. The cost component for the retailer includes holding, shortage, and both variable and fixed ordering costs. The retailer's objective is to maximize its discounted expected profit over the selling horizon by dynamically deciding on the optimal pricing and replenishment policy for each period. We show that, under a mild assumption on the additive demand function, at the beginning of each period an (s,S) policy is optimal for replenishment, and the value of the optimal price depends on the inventory level after the replenishment decision has been done. Our numerical study also suggests that for a sufficiently long selling horizon, the optimal policy is almost stationary. Furthermore, the fixed ordering cost (K) plays a significant role in our modeling framework. Specifically, any increase in K results in lower s and higher S. On the other hand, the profit impact of dynamically changing the retail price, contrasted with a single fixed price throughout the selling horizon, also increases with K. We demonstrate that using the optimal policy values from a model with backordering of unmet demands as approximations in our model might result in significant profit penalty. © 2005 Wiley Periodicals, Inc. Naval Research Logistics, 2006     

非磁化等离子体与电磁波的作用

为了将等离子体RCS减缩技术应用于飞行器上,首先从微观角度分析等离子体与电磁波的作用;然后通过计算机仿真技术,分析了等离子体对电磁波的吸收、反射性能;最后探讨了几种解决等离子体电磁兼容问题的方法。结果表明等离子体对电磁波有一定的吸收效果,并可通过控制覆盖在飞行器表面等离子体的形状改变飞行器的电磁外形。等离子体RCS减缩技术具有潜在的工程应用价值。