两机无等待流水车间调度问题的性质

针对两机无等待流水车间调度问题,提出目标函数最大完工时间最小化的快速算法,并给出算法的复杂度。分析两机无等待流水车间调度问题的排列排序性质,证明了两机无等待流水车间调度问题的可行解只存在于排列排序中,排列排序的最优解一定是两机无等待流水车间调度问题的最优解。最后研究了同时包含普通工件和无等待工件的两机流水车间调度问题的复杂性,为进一步研究两机无等待流水车间调度问题提供了理论依据。     

基于混合差分进化算法的无等待流水车间总流水时间优化*

以调度的总流水时间为优化目标, 提出一种混合差分进化算法。 首先, 建立无等待流水车间调度的问题模型,并用快速方法评估总流水时间指标。 其次,采用LPV规则,实现离散问题的连续编码; 用差分进化算法对总流水时间指标执行优化;引入插入邻域和基于pairwise的局部搜索算法, 分别对差分进化算法产生的新个体和差分进化算法的最优解执行邻域搜索, 达到优化目标全局和局部的最优。 最后,通过计算标准算例, 并与其他算法比较, 验证该混合差分进化算法的有效性。     

冷卷热处理生产调度模型的启发式算法

主要讨论某钢铁公司冷轧厂热处理车间冷卷热处理生产调度问题,将其归结为一类不允许等待的混合流水车间排序问题进行研究,建立相应的数学模型,设计求解其模型的启发式算法。     

确定型流水车间调度的遗传算法研究

为了验证遗传算法在解决确定型流水车间调度问题比其他启发式算法优越,分析了确定型流水车间调度的特点,并运用一种新的遗传算法求解该问题。为了提高效率,避免陷入局部最优,提出了一种合理的种群初始化方法,并成功地运用于求解确定型流水车间调度问题。实验结果证明了改进的遗传算法的实用性和可靠性,并具有较好的应用价值。     

量子萤火虫算法及在无等待流水调度上的应用

针对无等待流水车间调度问题,提出了一种新颖的量子萤火虫优化算法用于最小化总完工时间．首先,将量子进化机制嵌入萤火虫算法中,并设计一种快速的局部邻域搜索方法,在每次迭代时只搜索部分邻域,同时采用目标增量计算邻域解变化,这样极大地加快了算法迭代速度,加速了算法收敛．最后,应用Taillard基准测试实例仿真,与目前较优的启发式算法IHA（improved heuristic algorithm）和群智能算法DGSO（discrete glowworm swarm optimization）、 GA-VNS（genetic algorithm-variable neighborhood search）及DHS（discrete harmony search）相比较,产生最好解的平均百分比偏差均下降了40％以上．实验结果验证了所提算法在求解无等待流水调度中的优越性．     

置换流水车间调度的蚁群优化算法

提出了一种求解置换流水车间调度的蚁群优化算法。该算法的要点是结合了NEH启发式算法和蚁群优化方法。理论论证和对置换流水车间调度问题的基准测试表明了该算法的有效性。     

求解NWFS调度的改进和声搜索算法

以无等待流水车间(NWFS)总流水时间为优化目标,提出一种改进的和声搜索算法。建立NWFS调度优化的问题模型,设计总流水时间的快速评估方法。采用LPV规则实现离散问题的连续编码,给出改进的和声搜索算法对总流水时间执行优化,达到总流水时间的全局和局部最优。对标准算例做仿真,并在相同条件下与现有算法比较,验证该算法的可行性和有效性。     

基于目标增量的无等待流水调度快速迭代贪婪算法

最小化总完工时间无等待流水调度是典型的NP-完全问题,广泛存在于实际生产系统.改变传统求解调度序列目标函数的模式,提出目标增量法,通过目标函数变化量判断新解的优劣,大大降低算法所需计算时间;通过证明启发式算法基本操作的目标增量性质,设计两种基本目标增量法以快速评估新产生解的质量.提出快速迭代贪婪算法FIG(Fast Iterative Greedy algorithm)求解该问题,构造初始解生成算法,提出分段式重构局部搜索方法和迭代改进全局搜索策略以进一步提高解的质量.基于110个经典Benchmark实例,将提出的FIG算法与目前求解该问题较好的启发式算法PHlp和元启发式算法SRTS、DPSOvnd进行比较,实验结果表明FIG在性能上优于SRTS和PHlp,略逊于DPSOvnd;在效率上优于SRTS和DPSOvnd,略逊于PHlp.     

改进离散粒子群算法求解柔性流水车间调度问题

针对以最小化完工时间为目标的柔性流水车间调度问题(FFSP),提出了一种改进离散粒子群(DPSO)算法.所提算法重新定义粒子速度和位置的相关算子,并引入编码矩阵和解码矩阵来表示工件、机器以及调度之间的关系.为了提高柔性流水车间调度问题求解的改进离散粒子群算法的初始群体质量,通过分析初始机器选择与调度总完工时间的关系,首次提出一种基于NEH算法的最短用时分解策略算法.仿真实验结果表明,该算法在求解柔性流水车间调度问题上有很好的性能,是一种有效的调度算法.     

混合流水车间插单重调度的超启发式遗传算法

针对带有紧急订单的混合流水车间插单重调度问题,提出了一种双层编码的超启发式遗传算法。针对混合流水车间具有的订单排序和机器选择的双决策特征,在算法低层设计双层编码方案,在个体中表示订单排序和机器选择两类信息,对应一个唯一调度解,进而提出了12种排序和选择启发式对个体进行迭代优化;在算法高层采用自适应遗传算法,用来确定订单排序启发式和机器选择启发式的操作组合以及各组合执行的次序,并设计了自适应变异算子来优化算法的有效性。大规模数据实验的结果表明,所提算法具有很好的求解质量和求解效率。     

An improved heuristic to minimize total flow time for scheduling in the m-machine no-wait flow shop

In this paper, we present a constructive heuristic to minimize total flow time criterion for the well-known NP-hard no-wait flow shop scheduling problem. It is based on the assumption that the priority of a job in the initial sequence is given by the sum of its processing times on the bottleneck machines. The initial sequence of jobs thus generated is further improved using a new job insertion technique. We show, through computational experimentation, that the proposed method significantly outperforms the best-known heuristics while retaining its time complexity of O(n²). Statistical tests of significance are used to confirm the improvement in solution quality.     

Total flow time minimization in no-wait job shop using a hybrid discrete group search optimizer

The no-wait job shop scheduling problem is a well-known NP-hard problem and it is typically decomposed into timetabling subproblem and sequencing subproblem. By adopting favorable features of the group search technique, a hybrid discrete group search optimizer is proposed for finding high quality schedules in the no-wait job shops with the total flow time criterion. In order to find more promising sequences, the producer operator is designed as a destruction and construction (DC) procedure and an insertion-based local search, the scrounger operator is implemented by differential evolution scheme, and the ranger operator is designed by hybridizing best insert moves. An efficient initialization scheme based on Nawaz–Enscore–Ham (NEH) heuristic is designed to construct the initial population with both quality and diversity. A speed-up method is developed to accelerate the evaluation of the insertion neighborhood. Computational results based on well-known benchmark instances show that the proposed algorithm clearly outperforms a hybrid differential evolution algorithm and an iterated greedy algorithm. In addition, the proposed algorithm is comparable to a local search method based on optimal job insertion, especially for large-size instances.     

Two-stage hybrid flow shop with precedence constraints and parallel machines at second stage

This study deals with the two-stage hybrid flow shop (HFS) problem with precedence constraints. Two versions are examined, the classical HFS where idle time between the operations of the same job is allowed and the no-wait HFS where idle time is not permitted. For solving these problems an adaptive randomized list scheduling heuristic is proposed. Two global bounds are also introduced so as to conservatively estimate the distance to optimality of the proposed heuristic. The evaluation is done on a set of randomly generated instances. The heuristic solutions for the classical HFS in average are provably situated below 2% from the optimal ones, and on the other hand, in the case of the no-wait HFS the average deviation is below 5%.     

A new evolutionary clustering search for a no-wait flow shop problem with set-up times

This paper addresses the m-machine no-wait flow shop problem where the set-up time of a job is separated from its processing time. The performance measure considered is the total flowtime. A new hybrid metaheuristic Genetic Algorithm–Cluster Search is proposed to solve the scheduling problem. The performance of the proposed method is evaluated and the results are compared with the best method reported in the literature. Experimental tests show superiority of the new method for the test problems set, regarding the solution quality.     

An effective heuristic for flow shop problems with total flow time as criterion

This research studies on application of genetic algorithms for flow shop problems with total flowtime as the criterion. There is still very little research focusing on total flow time for flow shop problems. We develop a genetic algorithm based heuristic for the problems, and use an integer programming model and an existing heuristic to evaluate the efficiency of the genetic algorithm based heuristic. We generate a set of problems with different numbers of machines, different numbers of jobs, and solve ten of each of the problems using the integer programming model, the existing heuristic, and the genetic algorithm based heuristic, respectively. The results are very encouraging and appear to indicate the genetic algorithms are efficient approaches for flow shop problems.     

A discrete particle swarm optimization algorithm for the no-wait flowshop scheduling problem

In this paper, a discrete particle swarm optimization (DPSO) algorithm is presented to solve the no-wait flowshop scheduling problem with both makespan and total flowtime criteria. The main contribution of this study is due to the fact that particles are represented as discrete job permutations and a new position update method is developed based on the discrete domain. In addition, the DPSO algorithm is hybridized with the variable neighborhood descent (VND) algorithm to further improve the solution quality. Several speed-up methods are proposed for both the swap and insert neighborhood structures. The DPSO algorithm is applied to both 110 benchmark instances of Taillard [Benchmarks for basic scheduling problems. European Journal of Operational Research 1993;64:278–85] by treating them as the no-wait flowshop problem instances with the total flowtime criterion, and to 31 benchmark instances provided by Carlier [Ordonnancements a contraintes disjonctives. RAIRO Recherche operationelle 1978;12:333–51], Heller [Some numerical experiments for an M×J$\mathrm{M}\times \mathrm{J}$ flow shop and its decision-theoretical aspects. Operations Research 1960;8:178–84], and Revees [A genetic algorithm for flowshop sequencing. Computers and Operations Research 1995;22:5–13] for the makespan criterion. For the makespan criterion, the solution quality is evaluated according to the reference makespans generated by Rajendran [A no-wait flowshop scheduling heuristic to minimize makespan. Journal of the Operational Research Society 1994;45:472–8] whereas for the total flowtime criterion, it is evaluated with the optimal solutions, lower bounds and best known solutions provided by Fink and Voß [Solving the continuous flow-shop scheduling problem by metaheuristics. European Journal of Operational Research 2003;151:400–14]. The computational results show that the DPSO algorithm generated either competitive or better results than those reported in the literature. Ultimately, 74 out of 80 best known solutions provided by Fink and Voß [Solving the continuous flow-shop scheduling problem by metaheuristics. European Journal of Operational Research 2003;151:400–14] were improved by the VND version of the DPSO algorithm.     

The total completion time open shop scheduling problem with a given sequence of jobs on one machine

This paper addresses the open shop scheduling problem to minimize the total completion time, provided that one of the machines has to process the jobs in a given sequence. The problem is NP-hard in the strong sense even for the two-machine case. A lower bound is derived based on the optimal solution of a relaxed problem in which the operations on every machine may overlap except for the machine with a given sequence of jobs. This relaxed problem is NP-hard in the ordinary sense, however it can be quickly solved via a decomposition into subset-sum problems. Both heuristic and branch-and-bound algorithm are proposed. Experimental results show that the heuristic is efficient for solving large-scaled problems, and the branch-and-bound algorithm performs well on small-scaled problems.Scope and purposeShop scheduling problems, widely used in the modeling of industrial production processes, are receiving an increasing amount of attention from researchers. To model practical production processes more closely, additional processing restrictions can be introduced, e.g., the resource constraints, the no-wait in process requirement, the precedence constraints, etc. This paper considers the total completion time open shop scheduling problem with a given sequence of jobs on one machine. This model belongs to a new class of shop scheduling problems under machine-dependent precedence constraints. This problem is NP-hard in the strong sense. A heuristic is proposed to efficiently solve large-scaled problems and a branch-and-bound algorithm is presented to optimally solve small-scaled problems. Computational experience is also reported.     

A constructive heuristic for total flowtime minimization in a no-wait flowshop with sequence-dependent setup times

In this paper, we addressed the problem of scheduling jobs in a no-wait flow shop with sequence-dependent setup times with the objective of minimizing the total flow time. As this problem is well-known for being NP-hard, we present a new constructive heuristic, named QUARTS, in order to obtain good approximate solutions in a short CPU time. QUARTS breaks the problem in quartets in order to minimize the total flow time. The method was tested with other literature methods: BAH and BIH by Bianco et al. (1999) [6], TRIPS, by Brown et al. (2004) [7] and the metaheuristic Iterated Greedy with Local Search proposed by Ruiz and Stützle (2007) [25]. The computational results showed that IG_LS obtained the best results and QUARTS presented the best performance regarding other constructive heuristics.