Flow shop scheduling with earliness,tardiness, and intermediate inventory holding costs

We consider the problem of scheduling customer orders in a flow shop with the objective of minimizing the sum of tardiness, earliness (finished goods inventory holding), and intermediate (work‐in‐process) inventory holding costs. We formulate this problem as an integer program, and based on approximate solutions to two different, but closely related, Dantzig‐Wolfe reformulations, we develop heuristics to minimize the total cost. We exploit the duality between Dantzig‐Wolfe reformulation and Lagrangian relaxation to enhance our heuristics. This combined approach enables us to develop two different lower bounds on the optimal integer solution, together with intuitive approaches for obtaining near‐optimal feasible integer solutions. To the best of our knowledge, this is the first paper that applies column generation to a scheduling problem with different types of strongly ????‐hard pricing problems which are solved heuristically. The computational study demonstrates that our algorithms have a significant speed advantage over alternate methods, yield good lower bounds, and generate near‐optimal feasible integer solutions for problem instances with many machines and a realistically large number of jobs. © 2004 Wiley Periodicals, Inc. Naval Research Logistics, 2004.     

A spatial rank‐based multivariate EWMA control chart

Nonparametric control charts are useful in statistical process control when there is a lack of or limited knowledge about the underlying process distribution, especially when the process measurement is multivariate. This article develops a new multivariate self‐starting methodology for monitoring location parameters. It is based on adapting the multivariate spatial rank to on‐line sequential monitoring. The weighted version of the rank‐based test is used to formulate the charting statistic by incorporating the exponentially weighted moving average control scheme. It is robust to non‐normally distributed data, easy to construct, fast to compute and also very efficient in detecting multivariate process shifts, especially small or moderate shifts which occur when the process distribution is heavy‐tailed or skewed. As it avoids the need for a lengthy data‐gathering step before charting and it does not require knowledge of the underlying distribution, the proposed control chart is particularly useful in start‐up or short‐run situations. A real‐data example from white wine production processes shows that it performs quite well. © 2012 Wiley Periodicals, Inc. Naval Research Logistics 59: 91–110, 2012     

基于模糊层次分析法的非致命弹药安全管理系统评价

针对非致命弹药安全管理评估方面的空白,采用模糊层次分析法（FAHP）,从宏观上对非致命弹药安全管理系统进行评价。通过分析影响非致命弹药安全管理水平的因素,建立系统综合评价指标。分别建立不同指标间的模糊一致判断矩阵,确定隶属函数、权重值,最后得出定量评判结果,确定非致命弹药安全管理系统等级,对非致命弹药安全管理提供理论依据。     

油库储油区燃烧爆炸事故树分析

针对油库储油区安全管理点多面广的特点,分析储油区燃烧爆炸事故的相关影响因素和条件,建立完善的事故树模型。通过定性分析理清燃烧爆炸事故与基本事件之间的逻辑关系,定量分析获得各项基本事件的结构重要度排序,找出储油区存在燃烧爆炸隐患的重点部位,制订科学合理的安全信息监控点设置策略,为油库安全管理手段向信息化迈进提供决策依据。     

液氧与气氧对空气加热器燃烧流场的影响分析

针对一种基于液体火箭发动机燃烧室结构的空气加热器,采用数值仿真技术研究了加热器内部喷雾燃烧、燃气掺混以及出口流场分布等参数.分析对比了采用酒精/液氧/空气与酒精/气氧/空气两种不同氧化剂物态三组元同轴直流式喷嘴所得到的燃烧流场的区别,并通过改变燃烧室特征长度,分析了两种计算工况的加热器的性能差异.结果表明,喷入氧化剂的物态对燃烧流场影响较大,采用液氧喷嘴的火焰较长,气氧喷嘴的火焰分布较宽,且相对于液氧喷嘴,气氧喷嘴的燃烧室前端回流区由于掺混较多的燃气,导致喷注面板附近燃气温度较高,面板承热压力较大.设计的加热器均可保证两种喷嘴的出口流场品质较高,在保证流场出口品质的原则上,气氧喷嘴的燃烧室特征长度可至少小于液氧喷嘴的1/4.     

航天测控通信系统可靠性分析的Krylov子空间投影算法

基于Markov模型对航天测控通信系统进行可靠性分析的过程中,若系统中测控通信设备数量较多,模型中的状态空间随设备数量呈指数增长,将会导致数值计算困难.提出了一种基于Krylov子空间技术的可靠性分析方法,将大规模问题投影至小规模子空间中,求得问题的近似解.实验结果证明,Krylov子空间方法的计算速度及精度优于Ross方法和前向Euler法(forward Euler method,FEM).     

面向装备健康管理的可测性指标研究

可测性指标是开展可测性设计、验证和评估的依据.针对传统可测性指标主要用于故障可检测性和故障可隔离性水平评价,不能全面反映面向装备健康管理可测性水平的问题,在定性分析装备健康管理对可测性的本质需求基础上,从全域和瞬态角度提出了五个可测性指标以定量描述面向装备健康管理的可测性水平;并基于故障模式状态矢量给出了可测性指标的分析计算流程.最后以某装备柴油机的机体子系统为案例详细说明了可测性指标的计算过程,应用结果表明所提指标具有一定的可行性和合理性,可以有效指导面向装备健康管理的可测性优化设计.     

改进层次分析法在空面多目标攻击排序中的应用

建立了考虑目标的威胁、政治价值和经济价值属性的空面多目标攻击排序综合价值评估指标,应用模糊多属性理论和G.A.Miller九级量化理论对目标综合价值进行量化.建立了机群多目标攻击排序模型,采用熵值法求取各属性的权重从而构造判断矩阵,在此模型的基础上运用改进的层次分析法求解空面多目标攻击排序矩阵,从而为驾驶员的战术决策提供依据.     

关于半鞅向量随机积分的两个结果

首先利用半鞅Girsanov定理与闭图像定理证明了:若{Xn}是带滤基的完备概率空间(Ω,F,F,P)中的一列半鞅,其中滤基F=(Ft)t≥0满足通常条件,且{Xn}在关于P的Emery拓扑空间中收敛于X,则当概率测度Q相似文献   

YHCAPP系统工艺信息提取和工序图生成技术研究

YHCAPP系统是面向中小企业的工具型CAPP系统,如何从CAD图形提取工艺信息和生成工序图是该类系统的一个难点。文中给出了一种基于表达式求值的方法,成功解决了该难题,实际应用表明该方法稳定可靠。该方法也为一般的工具型CAPP系统提供了新思路。