电刷镀含纳米粉复合镀层结构和磨损性能

用含纳米金刚石粉的镍镀液电刷镀复合镀层,系统试验研究了复合镀层中纳米金刚石对镀层显微结构、力学性能及耐磨性能的影响.结果表明,纳米金刚石的弥散强化作用,可有效改善镀层的生长、减小内应力,提高镀层的显微硬度.含纳米金刚石粉的复合镀层在室温、高负荷下具有优良的抗疲劳和抗磨损性能,其耐磨性是纯镍镀层的4倍.     

泡沫塑料衬垫的粘弹性有限元分析

介绍了一种用于聚氨酯泡沫塑料衬垫的粘弹性有限元分析程序,利用积分本构关系计算了轴对称衬垫中的应力松弛。从数值结果可见,当衬垫贮存１０００小时以后,装配应力大约松弛了２５％。     

基于导弹空间飞行的空间碎片筛选方法研究

随着空间活动的日益频繁,空间碎片的数量也与日俱增,给远程弹道导弹的空间飞行安全带来巨大威胁。针对空间碎片数目繁多,为了快速进行导弹空间飞行安全预警和发射窗口选择,根据远程弹道导弹空间飞行特点,提出了适用于导弹与空间碎片碰撞预警的空间碎片筛选方法,并通过仿真计算证明了该筛选方法的科学性和合理性,该筛选方法可提高导弹空间飞行安全预警效率并缩短预警时间。     

Modeling and analysis of vessel casualties resulting from tanker traffic through narrow waterways

In this paper, we present a physics-based stochastic model to investigate vessel casualties resulting from tanker traffic through a narrow waterway. A state-space model is developed to represent the waterway and the location of vessels at a given time. We first determine the distribution of surface current at a given location of the waterway depending on channel geometry, bottom topography, boundary conditions, and the distribution of wind. Then we determine the distribution of the angular drift for a given vessel travelling at a given location of a waterway. Finally, we incorporate the drift probabilities and random arrival of vessels into a Markov chain model. By analyzing the time-dependent and the steady-state probabilities of the Markov chain, we obtain risk measures such as the probability of casualty at a given location and also the expected number of casualties for a given number of vessels arriving per unit time. Analysis of the Markovian model also yields an analytical result that shows that the expected number of casualties is proportional to square of the tanker arrival rate. We present our methodology on an experimental model of a hypothetical narrow waterway. © 1999 John Wiley & Sons, Inc. Naval Reseach Logistics 46: 871–892, 1999     

南方三年游击战争中的谭余保

1934年8月,湘赣苏区的主力红军红6军团奉命西征后,国民党军对苏区大举进攻,根据地越来越小,革命力量遭受重大损失.在这危急时刻,原湘赣省苏维埃政府主席谭余保组建中共湘赣临时省委,任省委书记兼组织部长,同时组建游击司令部,任政治委员兼司令员,运用灵活机动的游击战术,领导了湘赣边三年游击战争,同敌人进行了艰苦卓绝的斗争.     

心理战信息传送的受众心理分析

心理战信息传送的最终目标是在现代信息技术的作用下,使心理战信息为受众认同和接受,引起心理和行为的相应变化。从整个作战流程来看,心理战信息的传送过程模式为:特制的心理战信息-媒介或信息技术-受众(目标对象)。当信息作用于受众时,能否引起受众相应的心理反应,一般要经历注意-选择-理解-认同的内在心理活动过程,并具体表现为认知、情绪和意志三个维度上的相应变化。     

Optimizing usage and maintenance decisions for k‐out‐of‐n systems of moving assets

We consider an integrated usage and maintenance optimization problem for a k‐out‐of‐n system pertaining to a moving asset. The k‐out‐of‐n systems are commonly utilized in practice to increase availability, where n denotes the total number of parallel and identical units and k the number of units required to be active for a functional system. Moving assets such as aircraft, ships, and submarines are subject to different operating modes. Operating modes can dictate not only the number of system units that are needed to be active, but also where the moving asset physically is, and under which environmental conditions it operates. We use the intrinsic age concept to model the degradation process. The intrinsic age is analogous to an intrinsic clock which ticks on a different pace in different operating modes. In our problem setting, the number of active units, degradation rates of active and standby units, maintenance costs, and type of economic dependencies are functions of operating modes. In each operating mode, the decision maker should decide on the set of units to activate (usage decision) and the set of units to maintain (maintenance decision). Since the degradation rate differs for active and standby units, the units to be maintained depend on the units that have been activated, and vice versa. In order to minimize maintenance costs, usage and maintenance decisions should be jointly optimized. We formulate this problem as a Markov decision process and provide some structural properties of the optimal policy. Moreover, we assess the performance of usage policies that are commonly implemented for maritime systems. We show that the cost increase resulting from these policies is up to 27% for realistic settings. Our numerical experiments demonstrate the cases in which joint usage and maintenance optimization is more valuable. © 2017 Wiley Periodicals, Inc. Naval Research Logistics 64: 418–434, 2017     

不确定性作战任务形式化描述方法

针对复杂作战环境下作战任务的不可预知性特点,对不确定性任务的形式化描述方法进行了深入研究。分析不确定环境导致的任务分解和执行过程中存在的不确定性因素,从任务本身的不确定性、任务之间关系不确定性以及作战单元执行不确定性等方面,对不确定性任务进行了形式化描述,提出了不确定性任务形式化描述流程,最后通过一个实例对所提方法进行了验证。     

Exact expected values of variance estimators for simulation

We formulate exact expressions for the expected values of selected estimators of the variance parameter (that is, the sum of covariances at all lags) of a steady‐state simulation output process. Given in terms of the autocovariance function of the process, these expressions are derived for variance estimators based on the simulation analysis methods of nonoverlapping batch means, overlapping batch means, and standardized time series. Comparing estimator performance in a first‐order autoregressive process and the M/M/1 queue‐waiting‐time process, we find that certain standardized time series estimators outperform their competitors as the sample size becomes large. © 2007 Wiley Periodicals, Inc. Naval Research Logistics, 2007     

过氧化氢改善柴油机燃烧的试验研究

提出采用过氧化氢组液参与柴油机的燃烧,改善柴油机燃烧过程,同时降低油耗与排放的新方法。分析了过氧化氢对柴油机燃烧过程的影响机理,从实用角度设计并开发了一种过氧化氢组液供给系统,并在135柴油机单缸机上试验研究过氧化氢组液消耗量对比油耗、烟度、排温及NOx的影响。