基于TSAPO的柔性作业车间计划和调度

为使多目标柔性作业车间计划与调度的制定更适合实际生产的动态变化,提出增加动态反馈的闭环柔性作业车间计划模型及二阶式蚁群粒子群混合优化算法TSAPO。通过增加动态监视功能,及时更新和反馈实际生产数据。利用对优化目标的二阶段分解,设计带有反馈机制的调度算法。实验结果证明,该算法在求解多目标柔性作业车间调度问题中具有较好的优化效果。     

微粒群算法在印染企业车间调度中的研究应用

在对某印染企业的生产状况进行了深入调研和分析的基础上,对流水车间调度、混合流水车间调度和作业车间调度进行了对比研究。同时对微粒群算法进行了深入研究,并根据实际情况对算法进行了部分改动和改进,使之能适用于离散的生产调度问题。最后将改进后的微粒群算法应用到花布印染企业的车间调度中,对加工任务进行优化调度,并实现甘特图的动态生成。论文的结果可直接应用于企业流水车间调度和作业车间调度,具有一定的实际应用价值。     

微粒群优化算法在车间调度中的研究与应用

在对某印染企业的生产状况进行了深入调研和分析的基础上,对流水车间调度、混合流水车间调度进行了对比,同时对微粒群算法进行了深入研究,并根据实际情况对算法进行了部分改动和改进,使之能适用于离散的生产调度问题.最后将改进后的微粒群算法应用到印染企业的车间调度中,同时实现了甘特图的动态生成.研究结果可直接应用于企业流水车间调度和作业车间调度,具有一定的实际应用价值.     

基于人机协同的动态车间生产调试问题的研究与实现

针对传统的Job-Shop型车间生产调度研究只能解决静态调度问题的现状,在分析实际生产调度过程中可能发生的动态事件的基础上,深入研究了三类典型动态调度事件的动态响应机制以及动态调度过程中的几个关键算法,开发了基于以上研究的面向精密加工生产的车间调度系统,较好地解决了实际车间生产调度中出现的动态调度问题。     

考虑工件移动时间的柔性作业车间调度问题研究

分析生产车间的实际生产状况,建立了考虑工件移动时间的柔性作业车间调度问题模型,该模型考虑了以往柔性作业车间调度问题模型所没有考虑的工件在加工机器间的移动时间,使柔性作业车间调度问题更贴近实际生产,让调度理论更具现实性。通过对已有的改进遗传算法的遗传操作进行重构,设计出有效求解考虑工件移动时间的柔性作业车间调度问题的改进遗传算法。最后对实际案例进行求解,得到调度甘特图和析取图,通过对甘特图和析取图的分析验证了所建考虑工件移动时间的柔性作业车间调度问题模型的可行性和有效性。     

基于多Agent柔性制造单元的生产调度研究

针对基于制造单元的作业车间的生产调度问题进行了研究,结合多代理的智能性、灵活性和遗传算法的智能优化能力,建立基于多智能体的柔性制造单元的作业车间的调度系统模型.然后,提出了集成多智能体和遗传算法的动态调度策略和调度协商机制;最后,应用此方法完成了常规调度和异常调度的仿真算例.结果表明所开发系统可以解决基于加工单元的制造...     

作业车间动态调度建模与仿真研究

针对作业车间动态调度问题进行了分析和建模,应用多微粒群协同优化理论,提出了一种制造业作业车间动态调度优化算法,通过基于Matlab的模拟与仿真,验证了本算法的有效性和高效性.     

基于自适应蚁群算法的JSP问题仿真研究

研究车间作业调度优化问题,以实现资源优化配置。针对提高生产效率,缩短周期,降低成本,传统蚁群算法应用于JSP(车间作业调度问题)易出现停滞和陷入局部最优,以致作业调度效率低。为改善传统蚁群算法在车间作业调度的状况,提高车间作业调度效率,提出一种基于自适应蚁群(AACA)优化的车间作业调度算法模型。算法在基本蚁群算法中引入一种新的自适应机制,用于车间作业调度中。AACA在迭代初期快速搜索,可对后期精细寻优,克服了传统调度算法搜索JSP最优解时出现的收敛速度慢、精度不高的缺陷,对照实例进行仿真。仿真结果表明,采用的AACA调度算法在迭代100次以内能找到最优解或满意解,收敛速度快,精度高,优于传统的调度方法 GA、SA和SB,提高了作业调度效率,验证了AA-CA在实际生产中的有效性和实用性。     

模拟退火遗传算法在车间作业调度中的应用

研究车间作业调度系统,使资源达到优化配置.针对提高产品质量,缩短周期,传统遗传算法应用于车间作业调度过程中易出现收敛速度慢、易陷入局部最优,导致作业调度效率极低.为了提高车间作业调度的效率,提出一种模拟退火遗传算法的车间作业调度方法.在遗传算法种群更新过程引入模拟退火机制,防止早熟现象的产生,使种群在更新迭代过程中保持了多样性,加快了收敛速度,克服遗传算法过早收敛的缺陷.采用的SA-GA算法能够在最短时间找作业调度的最优解,对30个车间作业调度标准测试案例进行了仿真.仿真结果表明,使相对平均误差降低了4.6%,极大的提高了车间作业调度效率,验证了在实际生产中应用的可行和优越性.     

半导体制造业MES中的生产计划调度研究

生产计划调度是制造执行系统的核心.基于半导体制造业生产特点,研究了半导体制造业MES中的生产计划调度问题,给出生产计划调度系统的基本构架.根据客户需求制定生产计划,再细化为车间层可操作的作业计划,确定每台设备上加工安排,通过拟实调度处理动态不确定问题.通过生产计划制定、作业计划生成和拟实调度可以实现半导体制造生产过程平稳进行.     

Simulation studies in job shop sheduling—I a survey

The dynamic job shop scheduling problem has been studied extensively during the last two decades. Because of the complexity of the dynamic job shop scheduling problem, numerous simulation studies have been conducted and published in the area. These studies fall into one of the following categories: the studies comparing and/or developing scheduling rules which will give good shop performance under a given set of job and shop parameters, and the studies investigating sensitivity of shop performance to job and shop parameters under a given set of scheduling rules. In the literature, shop performance has been evaluated in terms of (1) criteria based on job completion times, (2) criteria based on due dates, (3) criteria based on costs. This paper discusses approaches taken in major simulation studies of dynamic job shop scheduling problem according to the above classification.     

RB-FIFT--一种结合Firstfit及预约回填策略的机群作业调度算法

机群作业管理是机群系统软件的重要组成部分,作业调度策略则是机群作业管理系统的核心．作业调度策略的选择不仅关系到机群系统的效率,还影响了用户作业的响应时间．目前,Firstfit调度算法已经相当成熟并且广泛应用于机群作业调度．传统的Firstfit算法虽然着眼于减少资源碎片,但未能解决作业饥饿问题．曙光超级服务器作业管理系统JMS改进了既有的结合Firstfit和优先级的作业调度算法P-FIFT,将预约和回填策略与Firstfit相结合,引入了新的RB-FIFT调度策略．实验结果表明,与传统Firstfit算法及P—FIFT算法比较,RB-FIFT调度策略不但能够消除系统中作业的饥饿现象,而且大大减少了资源碎片,提高了系统的吞吐率和资源利用率．     

A GEP-based reactive scheduling policies constructing approach for dynamic flexible job shop scheduling problem with job release dates

Flexible job shop scheduling problem (FJSSP) is generalization of job shop scheduling problem (JSSP), in which an operation may be processed on more than one machine each of which has the same function. Most previous researches on FJSSP assumed that all jobs to be processed are available at the beginning of scheduling horizon. The assumption, however, is always violated in practical industries because jobs usually arrive over time and can not be predicted before their arrivals. In the paper, dynamic flexible job shop scheduling problem (DFJSSP) with job release dates is studied. A heuristic is proposed to implement reactive scheduling for the dynamic scheduling problem. An approach based on gene expression programming (GEP) is also proposed which automatically constructs reactive scheduling policies for the dynamic scheduling. In order to evaluate the performance of the reactive scheduling policies constructed by the proposed GEP-based approach under a variety of processing conditions three factors, such as the shop utilization, due date tightness, problem flexibility, are considered in the simulation experiments. The scheduling performance measure considered in the simulation is the minimization of makespan, mean flowtime and mean tardiness, respectively. The results show that GEP-based approach can construct more efficient reactive scheduling policies for DFJSSP with job release dates under a big range of processing conditions and performance measures in the comparison with previous approaches.     

A new window-based job scheduling scheme for 2D mesh multicomputers

Allocating submeshes to jobs in mesh-connected multicomputers in a FCFS fashion can lead to poor system performance (e.g., long job waiting delays) because the job at the head of the waiting queue can prevent the allocation of free submeshes to other waiting jobs with smaller submesh requirements. However, serving jobs aggressively out-of-order can lead to excessive waiting delays for jobs with large allocation requests. In this paper, we propose a scheduling scheme that uses a window of consecutive jobs from which it selects jobs for allocation and execution. This window starts with the current oldest waiting job and corresponds to the lookahead of the scheduler. The performance of the proposed window-based scheme has been compared to that of FCFS and other previous job scheduling schemes. Extensive simulation results based on synthetic workloads and real workload traces indicate that the new scheduling strategy exhibits good performance when the scheduling window size is large. In particular, it is substantially superior to FCFS in terms of system utilization, average job turnaround times, and maximum waiting delays under medium to heavy system loads. Also, it is superior to aggressive out-of-order scheduling in terms of maximum job waiting delays. Window-based job scheduling can improve both overall system performance and fairness (i.e., maximum job waiting delays) by adopting large lookahead job scheduling windows.     

Single machine weighted earliness–tardiness penalty problem with a common due date

In this paper, we have considered a class of single machine job scheduling problems where the objective is to minimize the weighted sum of earliness–tardiness penalties of jobs. The weights are job-independent but they depend on whether a job is early or tardy. The restricted version of the problem where the common due date is smaller than a critical value, is known to be NP-complete. While dynamic programming formulation runs out of memory for large problem instances, depth-first branch-and-bound formulation runs slow for large problems since it uses a tree search space. In this paper, we have suggested an algorithm to optimally solve large instances of the restricted version of the problem. The algorithm uses a graph search space. Unlike dynamic programming, the algorithm can output optimal solutions even when available memory is limited. It has been found to run faster than dynamic programming and depth-first branch-and-bound formulations and can solve much larger instances of the problem in reasonable time. New upper and lower bounds have been proposed and used. Experimental findings are given in detail.Scope and purposeA class of single machine problems arising out of scheduling jobs in JIT environment has been considered in this paper. The objective is to minimize the total weighted earliness–tardiness penalties of jobs. In this paper, we have presented a new algorithm and conducted extensive empirical runs to show that the new algorithm performs much better than the existing approaches in solving large instances of the problem.     

基于蚁群优化算法的服务网格的作业调度

提出了利用蚁群算法来优化服务网格的作业调度系统的方法和一个两层的作业调度模型，该模型可以在网格的动态和异构环境下实现对作业执行时间的预测，然后根据作业的预测执行时间并利用蚁群优化算法使适应函数取得最小值，从而得到最优化的作业调度。基于开发的校园网格实验床，通过实验显示该方法可以优化服务网格的性能，减少作业的平均执行时问，提高系统的吞吐率。     

Scheduling multiple task graphs with end-to-end deadlines in distributed real-time systems utilizing imprecise computations

In order to meet the inherent need of real-time applications for high quality results within strict timing constraints, the employment of effective scheduling techniques is crucial in distributed real-time systems. In this paper, we evaluate by simulation the performance of strategies for the dynamic scheduling of composite jobs in a homogeneous distributed real-time system. Each job that arrives in the system is a directed acyclic graph of component tasks and has an end-to-end deadline. For each scheduling policy, we provide an alternative version which allows imprecise computations, taking into account the effects of input error on the processing time of the component tasks of a job. The simulation results show that the alternative versions of the algorithms outperform their respective counterparts. To our knowledge, an imprecise computations approach for the dynamic scheduling of multiple task graphs with end-to-end deadlines and input error has never been discussed in the literature before.     

Job shop scheduling under resource constraints and varying order priorities

This paper describes the development of a job shop scheduling system, which is based upon dynamic scheduling rules incorporating customer importance and/or order priority under constrained resources. An important part of the system is the development of a forecasting method for determining the estimated completion time for a job by estimating the future work load on the shop. The system has been developed from the analysis of the maintenance operations of a large petrochemical plant. The use of the computer programs which have been developed will be illustrated.     

Development of a new dioid algebraic model for manufacturing with the scheduling decision making capability

The dioid algebraic model, which is developed in this paper, captures the discontinuous nature of Discrete-Event Dynamic Systems and has widespread applicational capabilities. As a further improvement over existing dioid algebraic models, decision making capability is introduced to the developed dioid algebraic model. With this new capability, sequencing decisions at each machine can be represented in the model. Furthermore, the developed algebraic model is capable of representing job and resource unavailability, technological constraints, alternative process plans, and is easily modifiable to include new jobs and exclude finished jobs. In a possible application, the model can be used in representing dynamic scheduling problems and can be used as an important part of a real-time control and scheduling scheme of a manufacturing system.     

Job scheduling is more important than processor allocation forhypercube computers

Managing computing resources in a hypercube entails two steps. First, a job must be chosen to execute from among those waiting (job scheduling). Next a particular subcube within the hypercube must be allocated to that job (processor allocation). Whereas processor allocation has been well studied, job scheduling has been largely neglected. The goal of this paper is to compare the roles of processor allocation and job scheduling in achieving good performance on hypercube computers. We show that job scheduling has far more impact on performance than does processor allocation. We propose a new family of scheduling disciplines, called Scan, that have particular performance advantages. We show that performance problems that cannot be resolved through careful processor allocation can be solved by using Scan job-scheduling disciplines. Although the Scan disciplines carry far less overhead than is incurred by even the simplest processor allocation strategies, they are far more able to improve performance than even the most sophisticated strategies. Furthermore, when Scan disciplines are used, the abilities of sophisticated processor allocation strategies to further improve performance are limited to negligible levels. Consequently, a simple O(n) allocation strategy can be used in place of these complex strategies