考虑生产过程时间的柔性作业车间调度优化

通过研究生产过程时间,重新细分和定义等待时间,建立包括运输时间、调整时间、故障时间、等待时间、加工时间在内的柔性作业车间生产过程的时间模型,研究了柔性作业车间调度优化问题并设计了混合遗传算法的求解算法。最后,采用经典柔性作业车间调度用例,验证和对比了柔性作业车间调度的结果。结果表明,基于生产过程时间模型研究柔性作业车间调度问题,其优化性能有较好的改进,具有更好的实际应用价值。     

基于三方博弈的改进遗传算法求解多目标柔性作业车间调度

针对柔性作业车间的特点,以最小化完工时间、总机器负荷最小和临界机器负荷最小为目标,提出了基于三方博弈的改进遗传算法求解多目标柔性作业车间调度模型。通过三方博弈,使三个优化目标之间的博弈策略实现最优组合,从而获得子博弈完美纳什均衡,即为问题的优化组合解。为优化种群质量,将改进遗传算法应用于多目标柔性作业车间调度问题的求解过程,采用帕累托分类思想,对种群进行选择和精英保留,以优化种群结构;通过设计交叉、变异和局部搜索机制进一步寻找目标函数的最优解。为证明算法的有效性,运用基准算例对算法的求解性能进行了验证。其结果表明,所提算法在求解结果上有明显的改善,求解效率更高。     

基于改进遗传算法的偏柔性作业车间调度

偏柔性作业车间调度是生产管理中的重要问题。由于模型和计算的复杂性,传统优化方法往往难以得到最优解。采用改进遗传算法求解偏柔性作业车间的调度问题,设计相应的编码方法,利用所生成的染色体以及通过遗传操作得到的染色体生成可行的调度方案。基于工序串和机器串的编码方法,采用精英解保留策略、轮盘赌选择策略和基于划分集的交叉策略,提出基于均匀分布试验的变异法则,引入贪婪式解码方法对偏柔性作业车间调度进行求解。实例仿真表明,该算法在求解偏柔性作业车间调度方面具有良好的效率和优越性。     

混合工作日历下批量生产柔性作业车间多目标调度方法

提出了一种混合工作日历下批量生产柔性作业车间多目标调度方法。考虑设备的混合工作日历约束,构建了以生产周期最短、制造成本最低为优化目标的批量生产柔性作业车间多目标调度模型。设计了一种带精英策略的非支配排序遗传算法(NSGA II)求解该模型。算法中,采用“基于工序和设备的分段编码”方式分别对工序和设备进行编码;采用“基于工序和设备的分段交叉和变异方式”进行交叉和变异操作,采用“遗传算子改进策略”保证交叉、变异后子代个体的可行性;解码操作采用“基于平顺移动的原理”和“基于工作日历的时间推算技术”推算工序的调整开始、调整结束、加工开始和加工结束时刻。最后,通过案例分析验证了所提方法的有效性。     

基于深度强化学习的柔性作业车间节能调度研究

针对当前柔性作业车间节能调度研究无法充分利用历史生产数据,且对复杂、动态、多变的车间生产环境适应性不足的问题,引入深度强化学习思想,利用具有代表性的深度Q网络（deep Q-network, DQN）求解柔性作业车间节能调度问题。将柔性作业车间节能调度问题转化为强化学习对应的马尔科夫决策过程。进而,提炼表征车间生产状态特征的状态值作为神经网络输入,通过神经网络拟合状态值函数,输出复合调度动作规则实现对工件以及加工机器的选择,并利用动作规则与奖励函数协同优化能耗。在3个不同规模的案例上与非支配排序遗传算法、超启发式遗传算法、改进狼群算法等典型智能优化方法进行求解效果对比。结果表明,DQN算法有较强的搜索能力,且最优解分布情况与提出的柔性作业车间节能调度模型聚焦能耗目标相一致,从而验证了所用DQN方法的有效性。     

改进遗传算法解决柔性作业车间调度问题

柔性作业车间调度问题是经典作业车间调度问题的扩展,它允许工序在多台机器中的任意一台上加工.针对柔性作业车间调度问题的特点,提出一种扩展的基于工序的编码及其主动调度的解码机制,并设计一种初始解产生机制和两种有效的交叉和变异操作.为了克服传统遗传算法早熟和收敛慢的缺点,设计了精英解保留策略和子代产生模式结合的改进遗传算法应用于该调度问题.最后运用提出的算法求解基准测试问题验证算法的有效性.     

工期不确定的模具车间柔性Flow-shop调度问题

由于模具制造属于非重复性单件订货生产,模具加工的任务工期具有较强的不确定性,导致生产调度混乱。为制定合理可行的生产调度方案,建立了任务工期离散概率模型,以最大完工时间的期望值最小为目标,建立不确定工期柔性Flow-shop调度模型;在遗传算法交叉、变异等操作中融入模拟退火操作,将遗传算法的全局搜索能力与模拟退火算法的良好局部搜索能力相结合,设计了不确定工期的柔性Flow-shop调度问题混合遗传模拟退火算法。利用混合遗传模拟退火算法对调度模型进行求解,通过仿真实验表明,该研究对于解决工期不确定的模具车间柔性Flow-shop调度问题是行之有效的。     

应用改进蚁群算法求解柔性作业车间调度问题

将蚁群算法信息素更新规则进行改进,规定只有产生至今最优解的蚂蚁才能释放信息素,且只更新全局信息素,减少了传统蚁群算法的时间复杂度,提高了问题的求解效率。分析了柔性作业车间调度的特点,选取三个性能指标作为求解目标,设定其求解优先级,并建立相应的调度模型。将改进蚁群算法应用于柔性作业车间调度算例的求解,与其它算法比较,平均解有很大提高,表明了该算法求解柔性作业车间调度问题的有效性。     

基于最早完工时间疫苗的免疫遗传算法求解FJSLP

在生产过程中,车间作业调度的主要任务是确定工件在各台设备上的加工顺序,合理的调度方案能提高设备的利用率和企业的效益。针对柔性车间分批调度问题,采用免疫遗传算法进行求解。在疫苗技术方面,依据工件工序的加工信息,选择工件工序所能最早完工的机器作为疫苗,对相应工件个体机器码进行接种。通过对案例的测试,结果表明所采取的方法能求得更好的调度方案,减少作业总流程时间。     

遗传算法的双目标柔性作业车间调度研究

研究了FMS环境下先进制造车间路径柔性的优化调度问题.同时考虑现代生产准时制的要求,建立了柔性作业车间调度问题的双目标数学优化模型,并给出了求解模型的遗传算法的具体实现过程;针对模型的特殊性,提出了染色体两层编码结构,将AOV网络图应用到解码和适应度函数的计算中,通过一个调度实例进行验证,给出了相应的选择、交叉、变异操作设计方案.     

混合花朵授粉算法在作业车间调度中的应用

对最大完工时间最短的作业车间调度问题进行了研究,总结了当前求解作业车间调度问题的研究现状,提出一种花朵授粉算法与遗传算法的混合算法。混合算法以花朵授粉算法为基础,重新定义其全局搜索和局部搜索迭代公式,在同化操作过程中融入遗传算法的选择、优先交叉和变异操作,进一步增强算法的勘探能力。通过26个经典的基准算例仿真实验,并与近5年的其他算法比较,结果表明所提算法在求解作业车间调度问题具有一定优势。     

Optimal scheduling for flexible job shop operation

This paper presents a new integer linear programming (ILP) model to schedule flexible job shop, discrete parts manufacturing industries that operate on a make-to-order basis. The model considers groups of parallel homogeneous machines, limited intermediate buffers and negligible set-up effects. Orders consist of a number of discrete units to be produced and follow one of a given number of processing routes. The model allows re-circulation to take place, an important issue in practice that has received scant treatment in the scheduling literature. Good solution times were obtained using commercial mixed-integer linear programming (MILP) software to solve realistic examples of flexible job shops to optimality. This supports the claim that recent advances in computational power and MILP solution algorithms are making this approach competitive with others traditionally applied in job shop scheduling.     

Iterated greedy algorithms to minimize the total family flow time for job-shop scheduling with job families and sequence-dependent set-ups

This study addresses a variant of job-shop scheduling in which jobs are grouped into job families, but they are processed individually. The problem can be found in various industrial systems, especially in reprocessing shops of remanufacturing systems. If the reprocessing shop is a job-shop type and has the component-matching requirements, it can be regarded as a job shop with job families since the components of a product constitute a job family. In particular, sequence-dependent set-ups in which set-up time depends on the job just completed and the next job to be processed are also considered. The objective is to minimize the total family flow time, i.e. the maximum among the completion times of the jobs within a job family. A mixed-integer programming model is developed and two iterated greedy algorithms with different local search methods are proposed. Computational experiments were conducted on modified benchmark instances and the results are reported.     

装配作业车间分批调度问题的算法对比

建立最小化makespan的装配作业车间分批调度模型,利用遗传算法构建基于整体集成优化策略、分层迭代优化策略和双层进化策略的求解算法。它们的区别在于处理批量划分问题和子批调度问题的联合优化机制不同。最后通过仿真实验对比了几类算法的求解效果和收敛速度,并分析了它们的适应性特点。     

求解带AGV柔性作业车间调度问题的改进灰狼算法

针对带AGV的柔性作业车间调度问题,以最小化完工时间为目标,考虑AGV在装载站、机器、卸载站之间的有效负载时间和空载时间,构建了数学规划模型。其次,提出一种有效的灰狼算法进行求解,基于该问题特征,设计机器选择、工序排序和AGV搬运的3段编码,有效地保证每个个体均可产生可行解;灰狼算法中改进了关键参数a和E设定方式,有效平衡了算法的勘探能力和局部搜索能力;为进一步提升算法跳出局部最优解的能力,该算法融合了领域搜索等方法。最后,案例测试结果表明,改进灰狼算法在求解带AGV柔性作业车间调度问题中具有优越的性能。     

A genetic algorithm for flexible job shop scheduling with fuzzy processing time

This paper presents a flexible job shop scheduling problem with fuzzy processing time. An efficient decomposition-integration genetic algorithm (DIGA) is developed for the problem to minimise the maximum fuzzy completion time. DIGA uses a two-string representation, an effective decoding method and a main population. In each generation, DIGA decomposes the chromosomes of the main population into a job sequencing part and a machine assigning part and independently evolves the populations of these parts. Some instances are designed and DIGA is tested and compared with other algorithms. Computational results show the effectiveness of DIGA.     

Scheduling job shop associated with multiple routings with genetic and ant colony heuristics

The general job shop problem is one of the well known machine scheduling problems, in which the operation sequence of jobs are fixed that correspond to their optimal process plans and/or resource availability. Scheduling and sequencing problems, in general, are very difficult to solve to optimality and are well known as combinatorial optimisation problems. The existence of multiple job routings makes such problems more cumbersome and complicated. This paper addresses a job shop scheduling problem associated with multiple job routings, which belongs to the class of NP hard problems. To solve such NP-hard problems, metaheuristics have emerged as a promising alternative to the traditional mathematical approaches. Two metaheuristic approaches, a genetic algorithm and an ant colony algorithm are proposed for the optimal allocation of operations to the machines for minimum makespan time criterion. ILOG Solver, a scheduler package, is used to evaluate the performance of the proposed algorithms. The comparison reveals that both the algorithms are capable of providing solutions better than the solution obtained with ILOG Solver.     

Flexible job shop with continuous material flow

A new scheduling problem, the continuous flow flexible job shop (CF-FJS) is proposed. The formulation combines the well-known flexible job shop (FJS) problem and a dedicated continuous material flow model (MFM). In the MFM, operations are represented by material flow functions derived by integration of arbitrarily defined speed patterns. Two main concepts of the MFM formalism, i.e. variable speed of processing and continuous material flow, lead to position-dependent processing times and overlapping in operations which extend standard FJS formulation. Properties of the CF-FJS are investigated. A tabu search sched uling algorithm utilising these properties is proposed. Effective neighbourhood functions are defined based on elimination approaches. Two auxiliary procedures: search intensification level switching and fast feasibility detection are added to improve algorithm efficiency. The algorithm is verified using dedicated benchmark instances which comprise non-trivial representations of the CF-FJS specific features, i.e. machine efficiency patterns and minimum inter-operation buffers. The research is motivated by task scheduling in a fastener factory, but the presented results can be useful in many domains, such as production of granular goods, steel details, glass and fluids. The solution can be used in real-world applications. The published results can be helpful in testing new CF-FJS scheduling algorithms.