基于CBM-HTM的复杂系统预防性维修时机优化

针对目前复杂系统因多采用定周期预防性维修而造成维修费用过高、管理效率较低的情况,综合定周期维修(HTM)和基于状态的维修(CBM)两类技术,提出基于CBM-HTM的复杂系统预防性维修时机优化思路.并在此基础上,以费用最小为目标,建立基于CBM-HTM的复杂系统预防性维修时机优化模型.最后以由6个设备组成的复杂系统为例,进行了预防性维修时机优化算例说明.以期借助自主式保障中PHM、CBM技术,优化地面设备预防性维修时机,降低地面设备的预防性维修费用,提高地面设备维修管理的效率和效益.     

计及预防维修时间的一个故障维修模型

本文研究了单部件一个修理工组成的可修系统，为延长其使用寿命，在故障前考虑了预防维修，且假定预防维修能“修复如新”，而故障维修为“修复非新”时，利用几何过程，以系统２次数Ｎ为更换策略，选择最优的Ｎ，使得系统经长期运行单位时间的期望费用最小，最后，还对预防维修的定长间隔时间及更换策略进行了讨论。     

考虑中间库存缓冲区的多目标设备不完美预防维修策略研究

针对考虑库存缓冲区的多目标设备维修问题,以设备维修能力为约束条件,获得随机故障设备的不完美预防维修策略。首先,利用准更新过程,表示出设备的随机故障次数。其次,结合设备故障次数表达式,以最大设备可用度和最小生产总成本为多目标构建不完美预防维修模型,使用粒子群算法求解,优化设备可用度与生产总成本,获得更新周期内的库存量和预防维修周期两个决策变量的最优值。最后,通过算例分析,验证了多目标不完美预防维修模型的可用性。     

独立维修两部件并联系统可靠性的进一步分析

本文考虑了具有独立维修规则的两个不同型部件并联系统的可靠性问题，在一个部件的寿命为指数分布，维修分布为Ｅｒｌａｕｇ分布，另一个部件的寿命和维修分布均为一般连续型分布的条件下，我们得到了并系统的主要可靠性指标。     

航空公司维修不安全事件优先控制模型研究

鉴于机务维修不安全事件发生具有随机性、不确定性和复杂性等模糊灰色特性,建立了航空公司机务维修不安全事件模糊灰色关联优先控模型.以航空公司维修不安全事件为例,应用模型对航空公司维修不安全事件关联度和关联序进行了计算,得出了航空公司的维修不安全事件优先控制次序.结果表明,模型简单,易操作,能客观反映不安全事件发展趋势,为航空公司维修安全管理提供了一种更为科学的定量化依据.     

航空公司维修不安全事件优先控制模型研究北大核心

鉴于机务维修不安全事件发生具有随机性、不确定性和复杂性等模糊灰色特性,建立了航空公司机务维修不安全事件模糊灰色关联优先控模型.以航空公司维修不安全事件为例,应用模型对航空公司维修不安全事件关联度和关联序进行了计算,得出了航空公司的维修不安全事件优先控制次序.结果表明,模型简单,易操作,能客观反映不安全事件发展趋势,为航空公司维修安全管理提供了一种更为科学的定量化依据.     

基于综合重要度的动车组多部件系统机会维修策略研究

针对我国动车组列车现行维修方式,提出基于综合重要度序列的动车组多部件系统机会维修策略,对提高系统可靠度贡献大的关键部件进行准时优先维修。建立部件综合重要度指数计算模型,并依据其对部件维修优先级进行排序。以维修总成本最低为目标计算单部件最优维修周期及时刻,以系统维修总成本最低为目标,以关键部件的维修时刻为系统停机时刻建立考虑重要度的多部件系统机会维修模型。算例选取某型动车组四级修时更换的四部件系统为研究对象,讨论机会维修里程窗的大小及其偏移量对维修效果的影响,对比结果表明,考虑综合重要度的机会维修策略能够在维修费用基本持平的条件下,保证对系统可靠性贡献大的关键部件的可靠性,进而保证系统的整体可靠性。     

非正态总体控制图和预防维修策略耦合优化的研究

主要探讨非正态有偏总体的过程监控和预防维修耦合优化问题。假定设备故障率随时间递增,设备发生异常前在正常状态的停留时间服从威布尔分布,一旦发生异常将导致过程均值漂移。采用赋权方差法构造X控制图,将过程监控和预防维修策略联系起来,结合生产不合格品损失、抽样成本及维修成本等,构建综合损失模型,提出动态抽样方案、控制图参数和预防维修间隔的确定方法。最后对模型进行了灵敏度分析。     

有两种故障状态的两部件串联系统的预防维修策略

本文研究的是由两个部件串联组成且有两种故障状态的系统的预防维修策略, 当系统的工作时间达到T时进行预防维修, 预防维修使部件恢复到上一次故障维修后的状态。每个部件发生故障都有两种状态, 可维修和不可维修。当部件的故障为可维修故障时, 修理工对其进行故障维修, 且每次故障维修后的工作时间形成随机递减的几何过程, 每次故障后的维修时间形成随机递增的几何过程。当部件发生N次可维修故障或一次不可维修故障时进行更换。以部件进行预防维修的间隔和更换前的可维修故障次数N组成的二维策略(T, N) 为策略, 利用更新过程和几何过程理论求出了系统经长期运行单位时间内期望费用的表达式, 并给出了具体例子和数值分析。     

军用飞机维修质量管理的最优线性分派评估

在军机维修工作中,科学有效的管理,对及时完成维修任务,保障训练作战计划至关重要.在建立适合我军军机维修质量评估指标体系的基础上,定义了理想方案和贴近度,给出了排序频数的计算方法,进而将军机维修质量评估问题转化为最优线性分派问题来处理,从而为军机维修质量管理提供了一种科学、可靠的决策方法.     

On a class of self-similar processes with stationary increments in higher order Wiener chaoses

We study a class of self-similar processes with stationary increments belonging to higher order Wiener chaoses which are similar to Hermite processes. We obtain an almost sure wavelet-like expansion of these processes. This allows us to compute the pointwise and local Hölder regularity of sample paths and to analyse their behaviour at infinity. We also provide some results on the Hausdorff dimension of the range and graphs of multidimensional anisotropic self-similar processes with stationary increments defined by multiple Wiener–Itô integrals.     

A REPRESENTATION FORMULA RELATED TO SCHR(O)DINGER OPERATORS

Schr(o)dinger operator is a central subject in the mathematical study of quantum mechanics.Consider the Schrodinger operator H = -△ V on R, where △ = d2/dx2 and the potential function V is real valued. In Fourier analysis, it is well-known that a square integrable function admits an expansion with exponentials as eigenfunctions of -△. A natural conjecture is that an L2 function admits a similar expansion in terms of "eigenfunctions" of H, a perturbation of the Laplacian (see [7], Ch. Ⅺ and the notes), under certain condition on V.     

On a class of Riemann surfaces

It is considered the class of Riemann surfaces with dimT1 = 0, where T1 is a subclass of exact harmonic forms which is one of the factors in the orthogonal decomposition of the spaceΩH of harmonic forms of the surface, namely The surfaces in the class OHD and the class of planar surfaces satisfy dimT1 = 0. A.Pfluger posed the question whether there might exist other surfaces outside those two classes. Here it is shown that in the case of finite genus g, we should look for a surface S with dimT1 = 0 among the surfaces of the form Sg\K , where Sg is a closed surface of genus g and K a compact set of positive harmonic measure with perfect components and very irregular boundary.     

CONTENTS OF VOLUME 30

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Instructions for contributions

正Applied Mathematics-A Journal of Chinese Universities,Series B(Appl.Math.J.Chinese Univ.,Ser.B)is a comprehensive applied mathematics journal jointly sponsored by Zhejiang University,China Society for Industrial and Applied Mathematics,and Springer-Verlag.It is a quarterly journal with     

Journal of Mathematical Research with Applications Guide for Authors

正Journal overview:Journal of Mathematical Research with Applications(JMRA),formerly Journal of Mathematical Research and Exposition(JMRE)created in 1981,one of the transactions of China Society for Industrial and Applied Mathematics,is a home for original research papers of the highest quality in all areas of mathematics with applications.The target audience comprises:pure and applied mathematicians,graduate students in broad fields of sciences and technology,scientists and engineers interested in mathematics.     

Staircase transportation problems with superadditive rewards and cumulative capacities

A cumulative-capacitated transportation problem is studied. The supply nodes and demand nodes are each chains. Shipments from a supply node to a demand node are possible only if the pair lies in a sublattice, or equivalently, in a staircase disjoint union of rectangles, of the product of the two chains. There are (lattice) superadditive upper bounds on the cumulative flows in all leading subrectangles of each rectangle. It is shown that there is a greatest cumulative flow formed by the natural generalization of the South-West Corner Rule that respects cumulative-flow capacities; it has maximum reward when the rewards are (lattice) superadditive; it is integer if the supplies, demands and capacities are integer; and it can be calculated myopically in linear time. The result is specialized to earlier work of Hoeffding (1940), Fréchet (1951), Lorentz (1953), Hoffman (1963) and Barnes and Hoffman (1985). Applications are given to extreme constrained bivariate distributions, optimal distribution with limited one-way product substitution and, generalizing results of Derman and Klein (1958), optimal sales with age-dependent rewards and capacities.To our friend, Philip Wolfe, with admiration and affection, on the occasion of his 65th birthday.Research was supported respectively by the IBM T.J. Watson and IBM Almaden Research Centers and is a minor revision of the IBM Research Report [6].