设备的一种计划维修策略

本文根据设备在全寿命内有事后修理、计划修理和最后报废的实际情况,以全寿命内单位时间的更新维修期望费用最少为目标函数,建立一种数学模型,寻求设备在全寿命内最佳计划修理次数N和最佳的一组计划维修时间间隔集T。     

Capacitated lot‐sizing and scheduling with parallel machines,back‐orders,and setup carry‐over

We address the capacitated lot‐sizing and scheduling problem with setup times, setup carry‐over, back‐orders, and parallel machines as it appears in a semiconductor assembly facility. The problem can be formulated as an extension of the capacitated lot‐sizing problem with linked lot‐sizes (CLSPL). We present a mixed integer (MIP) formulation of the problem and a new solution procedure. The solution procedure is based on a novel “aggregate model,” which uses integer instead of binary variables. The model is embedded in a period‐by‐period heuristic and is solved to optimality or near‐optimality in each iteration using standard procedures (CPLEX). A subsequent scheduling routine loads and sequences the products on the parallel machines. Six variants of the heuristic are presented and tested in an extensive computational study. © 2009 Wiley Periodicals, Inc. Naval Research Logistics 2009     

基于状态的检查与修理综合决策模型

分析了单部件系统退化过程的特点,建立了基于状态的检查与修理决策模型。该模型根据系统的当前状态来决定检查与修理,通过分析计算系统在一个更新周期内平均检查次数、预防性维修及修复性故障的概率,建立维修费用与检查问隔及预防性维修阈值的关系,以平均维修费用最小为目标,优化检查间隔及预防性维修阈值。最后运用Matlab对模型进行数值计算,结果表明,模型能有效地降低维修费用。     

Machine scheduling with an availability constraint and job delivery coordination

In this paper we study the scheduling problem that considers both production and job delivery at the same time with machine availability considerations. Only one vehicle is available to deliver jobs in a fixed transportation time to a distribution center. The vehicle can load at most K jobs as a delivery batch in one shipment due to the vehicle capacity constraint. The objective is to minimize the arrival time of the last delivery batch to the distribution center. Since machines may not always be available over the production period in real life due to preventive maintenance, we incorporate machine availability into the models. Three scenarios of the problem are studied. For the problem in which the jobs are processed on a single machine and the jobs interrupted by the unavailable machine interval are resumable, we provide a polynomial algorithm to solve the problem optimally. For the problem in which the jobs are processed on a single machine and the interrupted jobs are nonresumable, we first show that the problem is NP‐hard. We then propose a heuristic with a worst‐case error bound of 1/2 and show that the bound is tight. For the problem in which the jobs are processed on either one of two parallel machines, where only one machine has an unavailable interval and the interrupted jobs are resumable, we propose a heuristic with a worst‐case error bound of 2/3. © 2006 Wiley Periodicals, Inc. Naval Research Logistics, 2007     

A new heuristic solution method in resource-constrained project scheduling

A new heuristic method is presented for the resolution of multiresource constrained conflicts in project scheduling. In attempting to find a minimal makespan solution, the algorithm employs a simple procedure to generate a feasible solution with no backtracking. A postanalysis phase then applies a hill-climbing search. The solution method is different from existing heuristic methods in that it repairs resource conflicts rather than constructs detailed schedules by dispatching activities. Resource-violating sets of activities are identified which must be prevented from concurrent execution because this would violate resource constraints. Repairs are made by imposing an arc to sequence two activities in such a resource violating set. Computational results are compared with those of existing heuristics for the minimal makespan problem.     

Cyclic scheduling in flow lines: Modeling observations,effective heuristics and a cycle time minimization procedure

In this paper we address the cyclic scheduling problem in flow lines. We develop a modeling framework and an integer programming formulation of the problem. We subsequently present exact and approximate solution procedures. The exact solution procedure is a branch-and-bound algorithm which uses Lagrangian and station-based relaxations of the integer programming formulation of the problem as the lower bounding method. Our heuristic procedures show a performance superior to the available ones in the literature. Finally, we address the stability issue in cyclic scheduling, demonstrate its relationship to the work-in-progress inventory control of a flow line, and present a very simple procedure to generate stable schedules in flow lines. © 1996 John Wiley & Sons, Inc.     

基于二维量度的复杂设备预防性维修决策优化

针对使用与维修具有两个测量维度的复杂设备,开展了其预防性维修决策的优化研究。基于二维量度的故障模式,给出了二维故障率的定量描述方法;分析了其预防性更换过程的基本过程,探讨了二维量度下更换周期对维修效果的影响,并从经济性角度建立了二维工龄更换费用模型;最后,采用算例的形式,对某设备维修决策同时考虑日历使用时间和行驶里程的情况,进行了二维更换间隔期的优化求解,从而验证了所建立方法与模型的实用性。     

Priority and dynamic scheduling in a make‐to‐stock queue with hyperexponential demand

We consider the scheduling problem in a make‐to‐stock queue with two demand classes that can be differentiated based on their variability. One class experiences Poisson arrivals and the other class experiences hyperexponential renewal arrivals. We provide an exact analysis of the case where the demand class with higher variability is given non‐preemptive priority. The results are then used to compare the inventory cost performance of three scheduling disciplines, first‐come first‐serve and priority to either class. We then build on an existing dynamic scheduling heuristic to propose a modification that works well for our system. Extensions of the heuristic to more than two classes and to the case where demand state is known are also discussed. © 2006 Wiley Periodicals, Inc. Naval Research Logistics, 2006.     

A heuristic approach to bicriteria scheduling

We consider the problem of sequencing jobs on a single machine while minimizing a nondecreasing function of two criteria. We develop a heuristic procedure that quickly finds a good solution for bicriteria scheduling. The procedure is based on using several arcs in the criterion space that are representative of the possible locations of nondominated solutions. By sampling a small number of points on these arcs, a promising point is identified in the criterion space for each arc. An efficient sequence in the neighborhood of each of the promising points is found and the best of these efficient sequences is selected as the heuristic solution. We implement the procedure for two different bicriteria scheduling problems: (i) minimizing total flowtime and maximum tardiness and (ii) minimizing total flowtime and maximum earliness. The computational experience on a wide variety of problem instances show that the heuristic approach is very robust and yields good solutions. © 1999 John Wiley & Sons, Inc. Naval Research Logistics 46: 777–789, 1999     

A simulated annealing approach to the cyclic staff-scheduling problem

This article presents the application of a simulated annealing heuristic to an NP-complete cyclic staff-scheduling problem. The new heuristic is compared to branch-and-bound integer programming algorithms, as well as construction and linear programming-based heuristics. It is designed for use in a continuously operating scheduling environment with the objective of minimizing the number of employees necessary to satisfy forecast demand. The results indicate that the simulated annealing-based method tends to dominate the branch-and-bound algorithms and the other heuristics in terms of solution quality. Moreover, the annealing algorithm exhibited rapid convergence to a low-cost solution. The simulated annealing heuristic is executed in a single program and does not require mathematical programming software. © 1993 John Wiley & Sons, Inc.     

Heuristic procedure for a multiproduct dynamic lot-sizing problem with coordinated replenishments

In this article we develop a heuristic procedure for a multiproduct dynamic lot-sizing problem. In this problem a joint setup cost is incurred when at least one product is ordered in a period. In addition to the joint setup cost a separate setup cost for each product ordered is also incurred. The objective is to determine the product lot sizes, over a finite planning horizon, that will minimize the total relevant cost such that the demand in each period for each product is satisfied without backlogging. In this article we present an effective heuristic procedure for this problem. Computational results for the heuristic procedure are also reported. Our computational experience leads us to conclude that the heuristic procedure may be of considerable value as a decision-making aid to production planners in a real-world setting. © 1994 John Wiley & Sons, Inc.     

The quay crane scheduling problem with time windows

The quay crane scheduling problem consists of scheduling tasks for loading and unloading containers on cranes that are assigned to a vessel for its service. This article introduces a new approach for quay crane scheduling, where the availability of cranes at a vessel is restricted to certain time windows. The problem is of practical relevance, because container terminal operators frequently redeploy cranes among vessels to speed up the service of high‐priority vessels while serving low‐priority vessels casually. This article provides a mathematical formulation of the problem and a tree‐search‐based heuristic solution method. A computational investigation on a large set of test instances is used to evaluate the performance of the heuristic and to identify the impact of differently structured crane time windows on the achievable vessel handling time. © 2011 Wiley Periodicals, Inc. Naval Research Logistics, 2011     

Easily computed approximations for (s,S) inventory system operating characteristics

The operating characteristics of (s,S) inventory systems are often difficult to compute, making systems design and sensitivity analysis tedious and expensive undertakings. This article presents a methodology for simplified sensitivity analysis, and derives approximate expressions for operating characteristics of a simple (s,S) inventory system. The operating characteristics under consideration are the expected values of total cost per period, holding cost per period, replenishment cost per period, backlog cost per period, and backlog frequency. The approximations are obtained by using least-squares regression to fit simple functions to the operating characteristics of a large number of inventory items with diverse parameter settings. Accuracy to within a few percent of actual values is typical for most approximations. Potential uses of the approximations are illustrated for several idealized design problems, including consolidating demand from several locations, and tradeoffs for increasing service or reducing replenishment delivery lead time.     

基于预防性维修工作组合的维修等级优化研究

针对单部件的维修间隔期无法反映系统的维修最佳间隔期这一问题,对装备各部件在各修理级别上的预防性维修任务组合情况进行了探索。通过建立费用模型作为决策模型,用以组合某一修理级别各部件的维修工作,得出系统预防性维修间隔期,并结合部队实际从系统的角度优化等级维修中的维修工作间隔期,为确定大、中、小修工作提供科学、合理的理论指导。该算法在区分各修理级别的维修能力的基础上,能较好地对各修理级别的维修工作组合情况进行了优化。实例验证了模型的实用性和有效性。     

Heuristic procedures for scheduling job families with setups and due dates

This paper examines heuristic solution procedures for scheduling jobs on a single machine to minimize the maximum lateness in the presence of setup times between different job families. It reviews the state of knowledge about the solution of this problem, which is known to be difficult to solve in general, and examines natural solution approaches derived from some of the underlying theory. The emphasis is on the design and computational evaluation of new heuristic procedures. © 1999 John Wiley & Sons, Inc. Naval Research Logistics 46: 978–991, 1999     

Coordinated overhaul scheduling of production units

This article presents a new approach to solve the problem of coordinating the overhaul scheduling of several nonidentical production units. For each production unit, we assume that the operating cost is an n-order polynomial function of the time elapsed since its previous overhaul. We develop an efficient iterative algorithm that generates a near-optimal cyclic overhaul schedule. We also construct a simple algorithm for the case where the overhaul interval for each production unit and the cycle time are restricted to be power-of-two multiples of some base planning period. Finally, we provide a worst-case performance bound for the solution to the problem under the power-of-two restriction. © 1994 John Wiley & Sons, Inc.     

Optimal maintenance and replacement policy for a deteriorating system with increased mean downtime

The problem of imperfect preventive maintenance (pm) and replacement schedule for a system which works below a specified failure rate is studied. For a given planning period, the optimal schedule for replacements to minimize the total cost is obtained. This article presents a branching algorithm with effective dominance rules to obtain the optimal schedule. Numerical illustration and computational experience are also presented.     

Scheduling economic lot sizes in deteriorating production systems

The paper considers the economic lot scheduling problem (ELSP) where production facility is assumed to deteriorate, owing to aging, with an increasing failure rate. The time to shift from an “in‐control” state to an “out‐of‐control” state is assumed to be normally distributed. The system is scheduled to be inspected at the end of each production lot. If the process is found to be in an “out‐of‐control” state, then corrective maintenance is performed to restore it to an “in‐control” state before the start of the next production run. Otherwise, preventive maintenance is carried out to enhance system reliability. The ELSP is formulated under the capacity constraint taking into account the quality related cost due to possible production of non‐conforming items, process inspection, and maintenance costs. In order to find a feasible production schedule, both the common cycle and time‐varying lot sizes approaches are utilized. © 2003 Wiley Periodicals, Inc. Naval Research Logistics 50: 650–661, 2003     

A heuristic network procedure for the assembly line balancing problem

Proposed is a Heuristic Network (HN) Procedure for balancing assembly lines. The procedure uses simple heuristic rules to generate a network which is then traversed using a shortest route algorithm to obtain a heuristic solution. The advantages of the HN Procedure are: a) it generally yields better solutions than those obtained by application of the heuristics, and b) sensitivity analysis with different values of cycle time is possible without having to regenerate the network. The rationale for its effectiveness and its application to problems with paralleling are presented. Computational experience with the procedure on up to 50 task test problems is provided.     

Joint determination of preventive maintenance and safety stocks in an unreliable production environment

In this article we formulate an analytical model of preventive maintenance and safety stock strategies in a production environment subject to random machine breakdowns. Traditionally, preventive maintenance and safety stocks have been independently studied as two separate strategies for coping with machine breakdowns. Our intent is to develop a unified framework so that the two are jointly considered. We illustrate the trade-off between investing in the two options. In addition, we provide optimality conditions under which either one or both strategies should be implemented to minimize the associated cost function. Specifically, cases with deterministic and exponential repair time distributions are analyzed in detail. We include numerical examples to illustrate the determination of optimal strategies for preventive maintenance and safety stocks. © 1997 John Wiley & Sons, Inc.