Evaluating cost and reliability integrated performance of stochastic logistics systems

The significance of integrating reliability into logistics performance has been established [The Logistics Performance Index and Its Indicators, World Bank International Trade and Transport Departments, (2010)]. Hence, as a response to the work by the World Bank, the present article aims to evaluate the performance index R_b,d of logistics systems as the probability that a specified demand d can be distributed successfully through multistate arc capacities from the source to the destination under the constraint that the total distribution cost should not exceed the cost limitation b. This article provides a pioneering approach for a straightforward computation of the performance index R_b,d. The proposed algorithm is a hybrid between the polynomial time capacity‐scaling algorithm, which was presented by Edmonds and Karp [JACM 19 (1972)], and the decomposition algorithm, which was presented by Jane and Laih [IEEE (2008)]. Currently, the proposed approach is the only algorithm that can directly compute R_b,d. An illustration of the proposed algorithm is presented. The results of the computational experiments indicate that the presented algorithm outperforms existing algorithms. © 2012 Wiley Periodicals, Inc. Naval Research Logistics, 2012     

Double Mover–Stayer model on customer switching in telecommunications industry

Customer acquisition and customer retention are the most important challenges in the increasingly competitive telecommunications industry. Traditional studies of customer switching always assume that customers are homogeneous, and thus that model customer switching behavior follows a Markov formulation. However, this postulation is obviously inappropriate in most instances. Blumen et al. (Cornell Studies of Industrial and Labor Relations, Cornell University Press, Ithaca, NY, 1955) developed the Mover–Stayer (MS) model, a generalization of the Markov chain model, to relax the requirement of homogeneity and allow the presence of heterogeneity with two different types of individuals—“stayers,” who purchase the same kinds of products or services throughout the entire observation period; and “movers,” who look for variety in products or services over time. There are two purpose of this article. First, we extend the MS model to a Double Mover‐Stayer (DMS) model by assuming the existence of three types of individuals in the market: (1) stable and loyal customers, who have stable usage within the same company; (2) instable but loyal customers, whose usage varies within the same company over time; and (3) disloyal customers, who switch from one company to another to seek for new experiences or/and benefits. We also propose an estimation method for the DMS model. Second, we apply the DMS model to telecommunications data and demonstrate how it can be used for pattern identification, hidden knowledge discovery, and decision making. © 2012 Wiley Periodicals, Inc. Naval Research Logistics, 2012     

空间非平稳高斯噪声背景下混合信号的DOA估计

针对空间非平稳高斯噪声背景下混合信号的DOA估计问题,提出了基于四阶累积量对混合波源的DOA估计算法。该算法首先构造四阶累积量矩阵,利用类似ESPR IT方法估计出所有非相关信源的DOA,然后对四阶累积量进行修正空间差分平滑去相干,消除非相关源和空间非平稳高斯噪声的影响,从而实现了对相干源的DOA估计。此方法通过分别估计非相关和相关或者相干信号的DOA,能够以较少的阵元实现对多个信号DOA估计,最后仿真实验也验证该算法的有效性。     

多源信息的验前分布融合方法研究

验前分布的获取和表示是B ayes理论应用中的一个关键问题。针对目前多源验前信息融合中存在的过分依赖专家信息的问题,提出了一种基于第2类极大似然估计原理(M L-II)确定验前分布权重的方法,该方法将现场试验数据看作是由其边缘分布产生的样本,然后根据不同验前分布下现场样本似然性的大小来确定其在验前分布融合中的作用,并以此进一步确定不同验前分布的权重因子。最后通过算例证明了该方法比基于专家信息的融合方法更为合理和有效。     

灰色神经网络的鱼雷经济寿命预测

为减少军费开支、降低鱼雷全寿命费用,从经济性角度提出了鱼雷最佳服役年限模型。利用灰色等维新息GM(1,1)模型对鱼雷年度使用维修费用进行预测;采用分组的思想将原始数据分为多组,采用神经网络对灰色模型的预测残差进行修正,以提高预测精度。通过实际算例预测了鱼雷经济寿命,从而证明了模型的实际应用价值。     

基于偏最小二乘回归的军用飞机采购价格预测

考虑到军用飞机采购价格样本数据少、难于预测的特点和偏最小二乘回归方法在处理小样本多元数据方面的优势,提出一种基于偏最小二乘回归的军用飞机价格预测方法.偏最小二乘回归首先提取第一、第二主成分对采购价格样本的特异点进行剔除;然后进行变量投影重要度分析来筛选变量;最后,偏最小二乘回归对筛选的变量进行回归建立军用飞机价格预测模型,并对军用飞机价格进行预测.结果表明,在军用飞机价格预测方面,与未筛选变量的回归模型和逐步多元回归相比,经过变量筛选的偏最小二乘回归模型预测的精度更高,更能体现采购价格与飞机性能参数之间的关系.     

延迟时间模型参数的极大似然估计

介绍了基于客观数据的延迟时间模型参数极大似然估计方法,提出了应用优化理论中的单纯形法求解似然函数的算法,为延迟时间模型的参数估计问题提供了可行的解决方法。通过计算机模拟数据的验证,此方法切实可行,结果可以满足需要。     

基于上下文的快速自适应运动估计算法

高效的运动估计算法是实时视频编解码技术的研究重点。为降低视频编码中运动估计的高计算复杂度问题,提出了基于上下文的快速自适应运动估计算法。该算法在运动估计过程中引入了次最佳匹配点,并且使用了一种基于平行四边形模式的方向性搜索策略。该算法的基本思想是:在块运动矢量估计过程中,利用前面搜索步中得到的块运动矢量及次最佳匹配点与最佳匹配点之间的位置关系,自适应选择一种平行四边形搜索模式,并确定下一步搜索的方向,进行更精确运动矢量的搜索。实验结果表明,该算法有效降低了视频压缩编码中运动估计的运算复杂度。     

Facility location for an extraterrestrial production/distribution system

This paper extends traditional production/distribution system analysis to address raw material, factories, and markets located beyond Earth. It explains the eventual advantages of such operations and discusses likely sites in the solar system. It furnishes a typology for production/distribution systems, assessing the fit of each type to space operations. It briefly reviews the physics of orbits. It develops transportation and inventory cost functions for the simplest case of Hohmann trajectories, and for transportation between circular orbits of similar radii using higher‐energy trajectories. These cost functions are used to derive a model of production/distribution system cost, the minimization of which selects an optimal factory location. The paper suggests potential extensions to this work, and concludes with ideas for location research on the novel reaches of extraterrestrial space. © 2005 Wiley Periodicals, Inc. Naval Research Logistics, 2005.     

基于试验研究的大型油罐冷却用水量估算

根据利用移动摇摆炮对10×10^4m^3着火油罐冷却试验的结果,对大型着火油罐冷却用水量实验和理论数据进行对比分析,得出冷却用水量的估算方法,为大型油罐火灾扑救提供参考和依据。