Efficient dispatching rules for dynamic job shop scheduling

This study attempts to provide efficient dispatching rules for dynamic job shop scheduling by combining different dispatching rules. A dispatching rule is used to select the next job to be processed from a set of jobs awaiting service. A job shop will be treated as dynamic, when conditions such as continuously arriving new jobs and deviations from current schedule need to be accommodated, and a job shop should be treated as an integrated part of a manufacturing system. The discussion includes a simulation technique which uses ARENA 4.0. software to simulate the dynamic model of a job shop under various rules and performance measures . Results of the simulation show that, for most of the performance measures, combined rules perform well. In this study, the combined rules MWKR_FIFO and TWKR_SPT do well under most conditions.     

Ant colony optimization for job shop scheduling using multi-attribute dispatching rules

This paper proposes a heuristic method based on ant colony optimization to determine the suboptimal allocation of dynamic multi-attribute dispatching rules to maximize job shop system performance (four measures were analyzed: mean flow time, max flow time, mean tardiness, and max tardiness). In order to assure high adequacy of the job shop system representation, modeling is carried out using discrete-event simulation. The proposed methodology constitutes a framework of integration of simulation and heuristic optimization. Simulation is used for evaluation of the local fitness function for ants. A case study is used in this paper to illustrate how performance of a job shop production system could be affected by dynamic multi-attribute dispatching rule assignment.     

New dispatching rules for scheduling in a job shop — An experimental study

We present two new dispatching rules for scheduling in a job shop. These rules combine the process-time and work-content in the queue for the next operation on a job, by making use of additive and alternative approaches. An extensive and rigorous simulation study has been carried out to evaluate the performance of the proposed dispatching rules compared with those by the SPT rule, the WINQ rule, a random rule based on the SPT and WINQ rules, and the best existing rule. The important aspects of the results of the experimental investigation are also discussed in detail.     

采用多个体交叉的遗传算法求解作业车间问题

为改善目前求解Job-Shop问题中的遗传算法的性能,加快搜索最优调度解的速度,首先分析了目前Job-Shop问题自身的求解难点和遗传算法的特点,并借鉴生物学的依据,提出了多个体交叉的遗传算法。该算法在遗传过程中采用多个体遗传算子,充分利用个体的优良性质,对不可行调度解根据多个体修补原则进行修正,可保证遗传后代的合法性和多样性,能够加快最优调度解的搜索时间。仿真结果充分证明了该算法的有效性。     

A dispatching rule-based hybrid genetic algorithm focusing on non-delay schedules for the job shop scheduling problem

Job shop scheduling is an important decision process in contemporary manufacturing systems. In this paper, we aim at the job shop scheduling problem in which the total weighted tardiness must be minimized. This objective function is relevant for the make-to-order production mode with an emphasis on customer satisfaction. In order to save the computational time, we focus on the set of non-delay schedules and use a genetic algorithm to optimize the set of dispatching rules used for schedule construction. Another advantage of this strategy is that it can be readily applied in a dynamic scheduling environment which must be investigated with simulation. Considering that the rules selected for scheduling previous operations have a direct impact on the optimal rules for scheduling subsequent operations, Bayesian networks are utilized to model the distribution of high-quality solutions in the population and to produce the new generation of individuals. In addition, some selected individuals are further improved by a special local search module based on systematic perturbations to the operation processing times. The superiority of the proposed approach is especially remarkable when the size of the scheduling problem is large.     

求解作业车间调度问题的多种群杂交遗传算法

提出了多种群杂交改进遗传算法,在约束条件处理中引入可能解空间概念;设计了机床编号可变的基于工序的编码。父代个体和交叉变异得到的个体在选择操作中具有同等选择机会,保证最优个体保留到下一代,又能保持子代的多样性。在遗传过程中引入修正种群,实现多种群杂交,以保持种群的多样性。应用实例分析和工程实践表明,算法稳定可靠,运行效率大大提高。     

Parallel line job shop scheduling using genetic algorithm

Parallel line job shop scheduling involves the optimal allocation and scheduling of jobs in multiple processing lines. Each job is allocated to a particular line and is processed to completion in that line. Also, all jobs allocated to a line are processed in a particular order. The objective of this paper is to find the optimal allocation of jobs to lines and also the optimal order of jobs processed in each line based on individual processing times and set up times. The optimal schedule gives the minimum makespan for the completion of all jobs. The optimization technique used is genetic algorithm.     

Multicontextual dispatching rules for job shops with dynamic job arrival

The dynamic job shop problem is more challenging than the static job shop problem because dynamic job shops are disrupted by unforeseen events such as job arrivals and machine breakdowns. Each phase of a dynamic job shop problem presents a unique set of circumstances; multicontextual functions can describe the unique characteristics of a dynamic job shop at a specific time. The present work examines 11 basic dispatching rules and 33 composite rules made with multicontextual functions (MCFs) that describe machine idle time (MIT) and job waiting time (JWT). Simple procedures are presented that allow one or both of MIT and JWT to be combined with a single basic dispatching rule. This procedure produced 33 composite dispatching rules; the schedules from all 44 rules for a job shop with dynamic job arrival were compared with regard to make span and mean flow time. One composite rule, most work remaining with MCF₂, produced schedules with the shortest make spans in 21 out of 27 cases; another composite rule, most remaining operations (MRO) with MCF₃, produced schedules with the shortest mean flow times in 27 out of 27 cases. It was possible to combine JWT and MIT usefully only when the relevant dispatching rule did not depend on operation processing time; because MRO did not consider processing time, it benefitted from both JWT and MIT. Clients who demand short mean flow times might benefit from an implementation of MRO with MCF₃.     

基于遗传退火算法的绿色作业车间调度

绿色制造和智能制造是工业发展的两大趋势,针对目前作业车间能耗大、设备利用率低,以及产品拖期严重等问题,以智能制造业环境中的作业车间为研究对象,建立了以车间总能耗和总拖期惩罚为优化目标的多目标调度模型,并通过设置权重系数来调节优化目标决策偏好;基于遗传算法收敛速度快、全局搜索能力强,以及模拟退火算法突跳性强的特点,设计一...     

基于改进遗传算法的车间调度问题求解

针对车间调度问题(Job Shop Problem,JSP)的特点,提出一种改进遗传算法。该方法利用剩余作业时间最多(MostWork Remaining,MWR)的工件优先排列的启发式规则来产生初始种群,并且在进化过程中采用分代交叉算子进行操作来避免算法早熟。通过分析算例结果表明,该改进遗传算法可以在进化初期就得到比较理想的调度方案,而且优化收敛速度快、结果优,更适用于解决车间调度问题。     

An effective hybrid genetic algorithm for the job shop scheduling problem

From the computational point of view, the job shop scheduling problem (JSP) is one of the most notoriously intractable NP-hard optimization problems. This paper applies an effective hybrid genetic algorithm for the JSP. We proposed three novel features for this algorithm to solve the JSP. Firstly, a new full active schedule (FAS) procedure based on the operation-based representation is presented to construct a schedule. After a schedule is obtained, a local search heuristic is applied to improve the solution. Secondly, a new crossover operator, called the precedence operation crossover (POX), is proposed for the operation-based representation, which can preserve the meaningful characteristics of the previous generation. Thirdly, in order to reduce the disruptive effects of genetic operators, the approach of an improved generation alteration model is introduced. The proposed approaches are tested on some standard instances and compared with other approaches. The superior results validate the effectiveness of the proposed algorithm.     

A two-stage genetic algorithm for large size job shop scheduling problems

The majority of large size job shop scheduling problems are non-polynomial-hard (NP-hard). In the past few decades, genetic algorithms (GAs) have demonstrated considerable success in providing efficient solutions to many NP-hard optimization problems. But there is no literature available considering the optimal parameters when designing GAs. Unsuitable parameters may generate an inadequate solution for a specific scheduling problem. In this paper, we proposed a two-stage GA which attempts to firstly find the fittest control parameters, namely, number of population, probability of crossover, and probability of mutation, for a given job shop problem with a fraction of time using the optimal computing budget allocation method, and then the fittest parameters are used in the GA for a further searching operation to find the optimal solution. For large size problems, the two-stage GA can obtain optimal solutions effectively and efficiently. The method was validated based on some hard benchmark problems of job shop scheduling.     

A neural network meta-model for identification of optimal combination of priority dispatching rules and makespan in a deterministic job shop scheduling problem

Selection of appropriate priority dispatching rules (PDRs) is a major concern in practical scheduling problems. Earlier research implies that using one PDR does not necessarily yield to an optimal schedule. Hence, this paper puts forward a novel approach based on discrete event simulation (DES) and artificial neural networks (ANNs) to decide on the optimal PDR for each machine from a set of rules so as to minimize the makespan in job shop scheduling problems. Non-identical PDRs are considered for each machine. Indeed, for a given number of machines, all permutations of PDRs are taken into account which could lead to nondeterministic polynomial-time hardness of the problem when the number of machines increases. To address this issue, DES and ANNs are employed as a meta-model. First, the problem is modeled and quite a number of feasible solutions are obtained from DES on its own. Afterward, a back-propagation neural network is developed in accordance with the results of DES to calculate the makespan based on all potential permutations of PDRs. The performance of the proposed approach is investigated through a set of test-bed problems.     

一种基于改进遗传算法的车间调度问题研究

作业车间调度是一类求解较困难的组合优化问题,在考虑遗传算法早熟收敛问题结合模拟退火算法局部最优时能概率性跳出的特性,该特性最终使算法能够趋于全局最优。在此基础上,将遗传算法和模拟退火算法相结合,提出了一种基于遗传和模拟退火的混合算法,该算法将模拟退火算法赋予搜索过程一种时变性融入其中,具有明显的概率跳跃性。同时。通过选取Brandimarte基准问题和经典的Benchmarks基准问题进行分析,并应用实例对该算法进行了仿真研究。该结果表明,通过模拟退火算法与遗产算法相集合,可以使计算的收敛精度明显提高,是行之有效的,与传统的算法相比较,有较明显的优越性。     

遗传算法在车间作业排序中的实现

描述了一种应用于车间作业排序的遗传算法的实现,该算法借助于对链表的灵活运用,使整体的运算时间得到提高,特别是对适应值的计算方式,既减轻遗传操作时合法性效验的负担,又模拟了加工过程,从而得到非常直观的运算结果.     

基于混合遗传算法的车间调度问题研究

利用遗传算法(GA)和模拟退火算法(SA)求解该问题近优解的有效性和实用性,提出一种实现车间调度的混合遗传算法(GASA),给出了一个新的编码方法,并建立了相应编码的解码规则.对初始温度的确定方法和获得适应度函数的方法进行了探讨.基于LA16调度问题,分别利用该方法和单纯遗传算法及模拟退火算法进行了模拟仿真计算,计算结果表明该混合算法克服了单纯遗传算法和模拟退火算法在车间调度优化方面的不足,具有较高的鲁棒性.     

Bottleneck identification procedures for the job shop scheduling problem with applications to genetic algorithms

Two bottleneck identification algorithms (one for bottleneck machines and the other for bottleneck jobs) are presented for the job shop scheduling problem in which the total weighted tardiness must be minimized. The scheduling policies on bottleneck machines can have significant impact on the final scheduling performance, and therefore, they need to be optimized with more computational effort. Meanwhile, bottleneck jobs that can cause considerable deterioration to the solution quality also need to be considered with higher priority. In order to describe the characteristic information concerning such bottleneck machines and bottleneck jobs, a statistical approach is devised to obtain the bottleneck characteristic values for each machine, and, in addition, a fuzzy inference system is employed to transform human knowledge into the bottleneck characteristic values for each job. These bottleneck characteristic values reflect the features of both the objective function and the current optimization stage. Finally, the effectiveness of the two procedures is verified by specifically designed genetic algorithms.     

基于遗传算法的作业车间调度研究与应用

提高大功率船舶柴油机的生产能力和水平,对提高我国造船行业的国际竞争力有着重要的意义。介绍作业车间调度问题,提出一种改进的遗传算法,同时将此算法应用于船舶柴油机的作业车间调度,该算法采用基于工序的编码方式,考虑了机床与工艺路线的约束,求解以关键设备的利用率最高和产品的加工周期最短为目标的静态调度问题,并通过具体的实例仿真分析其有效性。     

Analysis of dispatching rules in a stochastic dynamic job shop manufacturing system with sequence-dependent setup times

Stochastic dynamic job shop scheduling problem with consideration of sequence-dependent setup times are among the most difficult classes of scheduling problems. This paper assesses the performance of nine dispatching rules in such shop from makespan, mean flow time, maximum flow time, mean tardiness, maximum tardiness, number of tardy jobs, total setups and mean setup time performance measures viewpoint. A discrete event simulation model of a stochastic dynamic job shop manufacturing system is developed for investigation purpose. Nine dispatching rules identified from literature are incorporated in the simulation model. The simulation experiments are conducted under due date tightness factor of 3, shop utilization percentage of 90 % and setup times less than processing times. Results indicate that shortest setup time (SIMSET) rule provides the best performance for mean flow time and number of tardy jobs measures. The job with similar setup and modified earliest due date (JMEDD) rule provides the best performance for makespan, maximum flow time, mean tardiness, maximum tardiness, total setups and mean setup time measures.     

Interval job shop scheduling problems

This paper focuses on the design and development of an expert system for on-line detection of various control chart patterns so as to enable the quality control practitioners to initiate prompt corrective actions for an out-of-control manufacturing process. Using this expert system developed in Visual BASIC 6, all the nine most commonly observed control chart patterns, e.g., normal, stratification, systematic, increasing trend, decreasing trend, upward shift, downward shift, cyclic, and mixture can be recognized well, employing an optimal set of seven shape features. Based on an observation window of 32 data points, it can plot the control chart, compute the control limits, identify the control chart pattern, calculate the process capability index, determine the maximum run length, and identify the starting point of the maximum run length. After pattern recognition, it can also inform the users about various root assignable causes associated with a particular pattern along with the necessary pre-emptive actions. It opens up wide opportunities for quality improvement and real-time applications in diverse manufacturing processes. This developed expert system is built for a vertical drilling process and its recognition performance is tested using simulated process data.