基于降低运算复杂度的子空间跟踪算法稳健性分析

FDPM和FOOJA是目前两种最为有效的适用于主、次子空间跟踪的方法,属于低复杂度算法。进一步降低算法运算复杂度,对保证算法的实时性具有非常重要的意义。以降低算法运算复杂度为背景,通过对FDPM、FOOJA算法的分析,指出存在两种简化运算量的FDPM1stcol、FOOJA1stcol方法。在有限精度运算条件下,对四种方法的稳定性、数值鲁棒性进行了深入分析和讨论。通过实验仿真,对分析的结论进行了验证。     

Coordination of pricing and inventory control across products

We consider the joint pricing and inventory‐control problem for a retailer who orders, stocks, and sells two products. Cross‐price effects exist between the two products, which means that the demand of each product depends on the prices of both products. We derive the optimal pricing and inventory‐control policy and show that this policy differs from the base‐stock list‐price policy, which is optimal for the one‐product problem. We find that the retailer can significantly improve profits by managing the two products jointly as opposed to independently, especially when the cross‐price demand elasticity is high. We also find that the retailer can considerably improve profits by using dynamic pricing as opposed to static pricing, especially when the demand is nonstationary. © 2009 Wiley Periodicals, Inc. Naval Research Logistics, 2009     

新中国60年兵役制度的调整改革与发展趋势

新中国60年间,兵役制度经历了4次较大的调整改革:从革命战争年代的志愿兵役制到新中国成立初期的义务兵役制;从完全的义务兵役制到以义务兵为主体的义务兵与志愿兵相结合的兵役制;从义务兵为主、志愿兵为辅的兵役制到义务兵与志愿兵地位均等的兵役制;从以农村青年和城镇待业青年为兵员主体的兵役制到以各级各类院校应届毕业生为兵员主体的兵役制,并改革完善士官制度.在信息化条件下,兵役制度的改革将不断深化并出现新的发展趋向:在兵员构成上,逐渐走向志愿兵役制;在兵员素质上,大学生日益成为士兵方阵的主力;在军官队伍建设上,探索建立中国特色的军官职业化制度;在征兵方式上,时间地点将更为灵活;在兵员权利和义务上,义务分担也更为均衡,待遇更为优厚;在兵员征集手段上,网络技术广泛应用,效率不断提高.     

Approximation schemes for single‐machine scheduling with a fixed maintenance activity to minimize the total amount of late work

We consider the problem of scheduling n independent and simultaneously available jobs without preemption on a single machine, where the machine has a fixed maintenance activity. The objective is to find the optimal job sequence to minimize the total amount of late work, where the late work of a job is the amount of processing of the job that is performed after its due date. We first discuss the approximability of the problem. We then develop two pseudo‐polynomial dynamic programming algorithms and a fully polynomial‐time approximation scheme for the problem. Finally, we conduct extensive numerical studies to evaluate the performance of the proposed algorithms. © 2016 Wiley Periodicals, Inc. Naval Research Logistics 63: 172–183, 2016     

Stochastic regret minimization for revenue management problems with nonstationary demands

We study an admission control model in revenue management with nonstationary and correlated demands over a finite discrete time horizon. The arrival probabilities are updated by current available information, that is, past customer arrivals and some other exogenous information. We develop a regret‐based framework, which measures the difference in revenue between a clairvoyant optimal policy that has access to all realizations of randomness a priori and a given feasible policy which does not have access to this future information. This regret minimization framework better spells out the trade‐offs of each accept/reject decision. We proceed using the lens of approximation algorithms to devise a conceptually simple regret‐parity policy. We show the proposed policy achieves 2‐approximation of the optimal policy in terms of total regret for a two‐class problem, and then extend our results to a multiclass problem with a fairness constraint. Our goal in this article is to make progress toward understanding the marriage between stochastic regret minimization and approximation algorithms in the realm of revenue management and dynamic resource allocation. © 2016 Wiley Periodicals, Inc. Naval Research Logistics 63: 433–448, 2016     

稀薄流高超声速飞行器气动加热耦合计算

针对稀薄流域高超声速飞行器的气动加热问题,开展耦合数值计算研究。通过引入牛顿冷却定律,将直接模拟蒙特卡洛数值模拟方法与结构传热计算方法相结合,设计一种可对全机外形进行气动热和结构传热计算的高效松耦合方法,实现飞行器防热层结构材料温度分布特性的数值模拟。在以钝锥外形为例对直接模拟蒙特卡洛数值模拟程序进行验证的基础上,采用该方法对X37B轨道飞行器外形长时加热与结构传热过程进行数值模拟,给出结构温度及热流密度随飞行时间的变化规律。研究结果表明,设计的耦合计算方法能够模拟稀薄流域高超声速飞行器的气动加热及结构传热耦合过程,可为该类飞行器的气动热分析及热防护设计提供技术支持。     

软硬交替多层膜法向压入过程的有限元分析

采用大变形弹塑性有限单元法,对高速钢基体上的软硬交替多层膜在法向压痕作用下的力学行为,进行了模拟和分析.为了研究膜层数和膜厚的影响,对从单层到16层的不同膜层体系进行了计算.通过对诸如膜层的变形、最大应力随膜层数的变化、界面剪应力分布、表面张应力分布等的分析,得出了这些参数的分布及其对膜层体系的摩擦学性能的影响.这些结果可为多层膜的结构优化设计提供定量的依据.     

多功能虚拟仪器软面板的设计与实现

介绍了虚拟仪器的概念、特点 .运用虚拟仪器集成的设计思想 ,利用可视化图形编程环境 ,实现了多功能虚拟仪器软面板 ;对测试数据的保存、打印、测试过程的动态显示及仪器界面的转换等功能的实现作了深入的探讨 .     

INS 故障模型和推理方法的研究与设计

讨论了某型惯导 ( INS)设备的结构、工作流程和故障特点 ,分析了基于知识的专家系统 ( ES)常用的诊断模型和推理方法 ,在此基础上 ,设计了具体的基于对象的惯导综合层次模型及其推理机 .该模型和推理机已实际应用于该型 INS的故障诊断专家系统的设计     

新时期军队政治工作要为科技强军提供强大精神动力

新时期军队政治工作 ,必须突出科技强军这一时代要求 ,为科技强军提供强大的精神动力 ,既要为科技强军提供有力的思想舆论支持 ,又要为科技强军培养高素质的科技人才队伍 ,同时要实现政治工作自身的从思想观念到手段方法的超越和发展。