基于隐Markov树的序贯故障诊断模型

为了充分利用先验信息和实测信号,提高故障识别率,根据Bayes方法和序贯决策的思想,将实测信号分段,将前一段信号的诊断后验信息作为后一段信号的先验信息,提出了一种基于隐Markov树(hidden Markov tree,HMT)的序贯故障诊断模型.给出了诊断模型的建模步骤、HMT模型的建立方法和Bayes后验概率的计算方法.将模型应用于某型减速器故障诊断的结果表明,对于有先验信息和无先验情况,该序贯模型都可以有效地提高故障识别率.     

基于系统动力学的防空作战指挥关键因素分析

防空作战指挥效能的高低,对整个防空作战结局有着重要的影响.基于系统动力学的方法对防空作战指挥效能进行评估,分析了影响指挥效能的关键因素.进而提出加强对防空作战指挥不确定决策方法的研究和优化防空作战指挥体制两项对策措施以提高指挥效能.     

基于支持向量机的多分类军事目标识别应用

针对现代战场信息化程度的不断提高,电磁环境日趋复杂,侦查目标难以准确地识别情况,提出了运用支持向量机多分类器对军事侦查目标进行有效识别.结构风险最小化地支持向量机分类方法是小样本情况下统计机器学习的经典,具有速度快、泛化能力强等特点.用该算法建模军事目标的识别问题,达到了较高的识别准确率.所以应用在对侦查目标的识别上具有良好的效果,在军事应用上有较广阔的前景.     

基于模糊神经网络的反鱼雷深弹作战决策

反鱼雷深弹武器是水面舰艇对抗鱼雷的一种新的反鱼雷武器,由它组成的鱼雷防御系统可以拦截潜艇发射的声自导鱼雷、线导鱼雷及尾流自导鱼雷.根据其作战使用特点,建立基于模糊神经网络的智能辅助决策系统,分析了其基本思想,具体实现过程,并应用实例加以验证.计算结果表明:该模糊神经网络模型具有一定的合理性和实用性.     

多属性群决策理论的备件筛选方法

利用多属性群决策方法和多目标规划理论,建立了筛选武器装备维修备件的模型和方法.该方法首先按照多属性群决策方法对各种维修备件进行综合排序,然后再用多目标规划理论确定维修备件的选择方案.对该方法具体应用时的若干问题也进行了探讨.     

Optimal production ramp-up in the smartphone manufacturing industry

Motivated by challenges in the smartphone manufacturing industry, we develop a dynamic production ramp-up model that can be applied to economically satisfy nonstationary demand for short-life-cycle products by high-tech companies. Due to shorter life cycles and more rapid evolution of smartphones, production ramp-up has been increasingly critical to the success of a new smartphone. In the production ramp-up, the key challenge is to match the increasing capacity to nonstationary demand. The high-tech smartphone manufacturers are urged to jointly consider the effect of increasing capacity and decreasing demand. We study the production planning problem using a high-dimensional Markov decision process (MDP) model to characterize the production ramp-up. To address the curse of dimensionality, we refine Monte Carlo tree search (MCTS) algorithm and theoretically analyze its convergence and computational complexity. In a real case study, we find that the MDP model achieves revenue improvement by stopping producing the existing product earlier than the benchmark policy. In synthetic instances, we validate that the proposed MCTS algorithm saves computation time without loss of solution quality compared with traditional value iteration algorithm. As part of the Lenovo production solution, our MDP model enables high-tech smartphone manufacturers to better plan the production ramp-up.     

采用3电平非均匀量化的脉冲编码策略

作为全数字发信机系统中广泛应用的一种脉冲编码技术,Delta-Sigma调制(Delta-Sigma Modulation, DSM)通过增加量化电平,能够实现调制性能的提升。但限于全数字发信机系统开关功放的具体结构,多电平DSM序列无法直接驱动后级功放电路。在传统3电平DSM基础上,通过引入面积等效原理和非均匀量化技术,提出了适用于开关功放的一种新的脉冲编码策略。理论分析和仿真结果表明,相比常规2电平DSM序列,采用该策略获得的调制脉冲序列具有更优的带内SNR和编码效率性能。     

Revenue maximization in two-station tandem queueing systems

We study optimal pricing for tandem queueing systems with finite buffers. The service provider dynamically quotes prices to incoming price sensitive customers to maximize the long-run average revenue. We present a Markov decision process model for the optimization problem. For systems with two stations, general-sized buffers, and two or more prices, we describe the structure of the optimal dynamic pricing policy and develop tailored policy iteration algorithms to find an optimal pricing policy. For systems with two stations but no intermediate buffer, we characterize conditions under which quoting either a high or a low price to all customers is optimal and provide an easy-to-implement algorithm to solve the problem. Numerical experiments are conducted to compare the developed algorithms with the regular policy iteration algorithm. The work also discusses possible extensions of the obtained results to both three-station systems and two-station systems with price and congestion sensitive customers using numerical analysis.     

It Takes Two to Tango: Autocratic underbalancing,regime legitimacy and China’s responses to India’s rise

What factors do autocracies evaluate when responding to perceived threats and why might they fail to balance appropriately? I posit that autocratic leaders may choose greater exposure to an external threat if, by doing so, it preserves regime legitimacy. Specifically, the desire to promote a positive image to one’s domestic public creates incentives to publicly downplay a rival’s military progress, which then affects the state’s ability to mobilize resources to respond to the growing threat. I test this theory in the case of China’s response to India’s military rise. This research contributes to balancing theory and empirical work on East Asian security.     

Nash bargaining over allocations in inventory pooling contracts

When facing uncertain demand, several firms may consider pooling their inventories leading to the emergence of two key contractual issues. How much should each produce or purchase for inventory purposes? How should inventory be allocated when shortages occur to some of the firms? Previously, if the allocations issue was considered, it was undertaken through evaluation of the consequences of an arbitrary priority scheme. We consider both these issues within a Nash bargaining solution (NBS) cooperative framework. The firms may not be risk neutral, hence a nontransferable utility bargaining game is defined. Thus the physical pooling mechanism itself must benefit the firms, even without any monetary transfers. The firms may be asymmetric in the sense of having different unit production costs and unit revenues. Our assumption with respect to shortage allocation is that a firm not suffering from a shortfall, will not be affected by any of the other firms' shortages. For two risk neutral firms, the NBS is shown to award priority on all inventory produced to the firm with higher ratio of unit revenue to unit production cost. Nevertheless, the arrangement is also beneficial for the other firm contributing to the total production. We provide examples of Uniform and Bernoulli demand distributions, for which the problem can be solved analytically. For firms with constant absolute risk aversion, the agreement may not award priority to any firm. Analytically solvable examples allow additional insights, e.g. that higher risk aversion can, for some problem parameters, cause an increase in the sum of quantities produced, which is not the case in a single newsvendor setting. © 2008 Wiley Periodicals, Inc. Naval Research Logistics, 2008