对流层散射双向时间比对中对流层斜延迟估计

为精确估计对流层散射双向时间比对系统中对流层斜延迟,分析了估计卫星信号对流层斜延迟的Hopfield天顶延迟模型及CFA2.2映射函数模型并对其进行修正,从而适用于对流层散射斜延迟的精确估计。根据北纬35°~37°范围内的三个测站2010—2012三年的气象数据,验证Hopfield模型精度范围小于35 mm,并将三个测站按相互之间基线距离的不同分为三组比对站,利用2012年的气象数据,计算在不同入射角下一年的对流层散射斜延迟,并得出最大斜延迟对应的年积日和入射角。结果表明,三组比对站的最大单向散射斜延迟为21.82~35.45 m。在双向比对抵消90%的情况下,时间延迟为7.3 ns~11.7 ns;相互抵消95%时,时间延迟为3.6 ns~5.9 ns。     

Approximation algorithms for sequential batch‐testing of series systems

We introduce and study a generalization of the classic sequential testing problem, asking to identify the correct state of a given series system that consists of independent stochastic components. In this setting, costly tests are required to examine the state of individual components, which are sequentially tested until the correct system state can be uniquely identified. The goal is to propose a policy that minimizes the expected testing cost, given a‐priori probabilistic information on the stochastic nature of each individual component. Unlike the classic setting, where variables are tested one after the other, we allow multiple tests to be conducted simultaneously, at the expense of incurring an additional set‐up cost. The main contribution of this article consists in showing that the batch testing problem can be approximated in polynomial time within factor , for any fixed . In addition, we explain how, in spite of its highly nonlinear objective function, the batch testing problem can be formulated as an approximate integer program of polynomial size, while blowing up its expected cost by a factor of at most . Finally, we conduct extensive computational experiments, to demonstrate the practical effectiveness of these algorithms as well as to evaluate their limitations. © 2016 Wiley Periodicals, Inc. Naval Research Logistics 63: 275–286, 2016     

复杂目标毁伤效果评估关键问题分析

复杂目标毁伤效果评估一直是毁伤效果评估中的重难点问题,作为作战指挥决策的重要依据,对其关键问题进行分析和研究具有重要现实意义。首先总结和梳理复杂目标毁伤效果评估的基本思路,在此基础上归纳出复杂目标毁伤效果评估的一般步骤,并构建毁伤效果评估的基本框架,明确其中的关键环节和问题,并基于现有复杂目标毁伤效果评估的方法和模型对其进行详细的论述和分析,最后指明未来发展的方向。     

基于端点梯形白化权函数的飞机保障性灰色评估

保障性评估是提高飞机保障性的有效手段。从保障性的定义出发,构建了飞机保障性评估指标体系,在利用层次分析法(AHP)确定指标权重的基础上,对三角白化权函数进行了改进,建立了基于端点梯形白化权函数灰色评估模型,很好地解决了相邻的若干类别对该类别聚类中心的影响问题,并将其应用于飞机保障性的评估,通过实例分析,验证了此评估方法的可行性,对提升飞机保障性评估的准确性有一定的参考价值。     

基于可用度的电子设备告警系统检查策略研究

针对电子设备告警系统故障具有隐蔽性的特点,考虑检查不完善的因素,运用延迟时间概念,以系统期望可用度最大为优化目标,建立了电子设备隐蔽功能故障检查优化模型。提出了优化检查间隔期的算法,并通过实际案例验证了模型的有效性。     

基于双光频梳及受激布里渊散射的微波频率测量

提出了一种基于双光频梳和受激布里渊散射的高精度微波频率测量方法,利用两个双平行马赫-曾德尔调制器将待测微波信号和扫描信号调制在两路光频梳上,并分别作为信号光和泵浦光输入色散位移光纤中。利用双光频梳和不断频移的扫描信号,系统可同时实现波分复用和时分复用。同时,在双光频梳和受激布里渊散射的作用下,系统可发生一系列的受激布里渊散射,通过测量各信道输出的光功率实现待测微波频率的测量。为进一步提升测量精度,利用测量得到的光功率值构建幅度比较函数,从而实现频率测量误差修正。通过实验仿真验证了所提方法的有效性,测量误差为±2.5 MHz。     

利用AHP确定决策方案排序的一种改进方法

针对在用AHP法求解权重排序向量时 ,用不同的计算方法导致排序方案不一致的矛盾现象 ,提出了一种在单准则下综合各个排序方案信息的方法 ,使AHP法更趋于完善     

气泡输运方程及其应用

舰船尾流中含有大量的不同直径的气泡 ,尾流的几何特性与产生它的舰船大小、航行速度、海面风速等因素有很大的关系 ,对气泡规律的研究无论在理论还是在应用中都具有重要的意义。介绍了水中气泡分布函数 ,推导了分布函数所满足的输运方程 ,并给出了气泡输运方程的特征解。对影响分布函数的因素作了探讨 ,并利用输运方程对具体问题进行了计算。结果表明 ,运用气泡输运方程可解决气泡的分布、输运问题 ,并可对气泡分布与气泡半径、气泡所处深度的关系作出定量分析     

发挥图书馆在军校素质教育中的作用

提高军校学员的综合素质,实施素质教育,其任务不仅是文化的传递和能力的培养,而要在传授知识、发展能力的基础上,着重培养学员的人文精神和科学素养.文章论述了图书馆在加强军校素质教育中的作用、功能以及具体措旌.     

A nonparametric approach to accelerated life testing under multiple stresses

Accelerated life testing (ALT) is concerned with subjecting items to a series of stresses at several levels higher than those experienced under normal conditions so as to obtain the lifetime distribution of items under normal levels. A parametric approach to this problem requires two assumptions. First, the lifetime of an item is assumed to have the same distribution under all stress levels, that is, a change of stress level does not change the shape of the life distribution but changes only its scale. Second, a functional relationship is assumed between the parameters of the life distribution and the accelerating stresses. A nonparametric approach, on the other hand, assumes a functional relationship between the life distribution functions at the accelerated and nonaccelerated stress levels without making any assumptions on the forms of the distribution functions. In this paper, we treat the problem nonparametrically. In particular, we extend the methods of Shaked, Zimmer, and Ball [7] and Strelec and Viertl [8] and develop a nonparametric estimation procedure for a version of the generalized Arrhenius model with two stress variables assuming a linear acceleration function. We obtain consistent estimates as well as confidence intervals of the parameters of the life distribution under normal stress level and compare our nonparametric method with parametric methods assuming exponential, Weibull and lognormal life distributions using both real life and simulated data. © 1998 John Wiley & Sons, Inc. Naval Research Logistics 45: 629–644, 1998