基于强化学习的多技能项目调度算法

多技能项目调度存在组合爆炸的现象, 其问题复杂度远超传统的单技能项目调度, 启发式算法和元启发式 算法在求解多技能项目调度问题时也各有缺陷. 为此, 根据项目调度的特点和强化学习的算法逻辑, 本文设计了基 于强化学习的多技能项目调度算法. 首先, 将多技能项目调度过程建模为符合马尔科夫性质的序贯决策过程, 并依 据决策过程设计了双智能体机制. 而后, 通过状态整合和行动分解, 降低了价值函数的学习难度. 最后, 为进一步提 高算法性能, 针对资源的多技能特性, 设计了技能归并法, 显著降低了资源分配算法的时间复杂度. 与启发式算法的 对比实验显示, 本文所设计的强化学习算法求解性能更高, 与元启发式算法的对比实验表明, 该算法稳定性更强, 且 求解速度更快.     

多星联合动态调度问题的启发式算法研究

对地观测多星联合动态调度问题是一类复杂的调度问题。在对多星联合动态调度问题的动态来源进行深入分析的基础上,对该问题进行了统一描述。针对问题的特点,提出了一种基于规则的启发式求解算法,设计了最大竞争度的退出启发式规则和最小冲突度的插入启发式规则。最后给出了一个应用实例,对算法进行了验证。     

求解任务可拆分多项目协同调度问题的启发式算法

生产项目计划与调度过程中任务可以被拆分为更小粒度的子任务分批次执行,实现缩短项目总工期的优化目标.针对抢占式任务可拆分多项目调度问题,从协同优化角度探讨任务拆分与重组方式,提出一个长工期任务优先拆分、长工期项目优先拆分和高资源利用率项目优先拆分3种任务拆分优先级判断规则,设计一种求解任务可拆分多项目协同调度问题的启发式算法.最后通过数值实例和仿真分析验证了所提出方法在多项目调度总工期的优化效果和求解效率.     

改进的蚁群算法求解多目标车间作业调度问题

目前已经有许多解决作业车间调度问题的启发式求解方法,但这些方法多数局限于单目标,因此不能满足现实生活中多目标作业车间调度问题的应用需求.提出一种改进的蚁群算法启发式地搜索多目标车间作业调度问题的近似最优解以满足实际的应用需求.通过对转移概率以及信息素更新方式进行改进,并融合交叉策略,确保算法在加快搜索收敛速度的同时又避免陷入局部最优.仿真实验证明,改进的算法具有较好的性能,能够解决实际生活中的多目标作业车间调度问题.     

Scheduling Algorithm of α-Planarization for Solving the Problem of Multiprocessor Scheduling

在分析多处理机调度问题的基础上,提出了α-平坦的概念,并将其引入到多处理机调度问题中;基于此,提出了一种新的基于α-平坦的求解多处理机调度问题的算法.算法首先对作业集合做平坦化处理,然后再对处理后所得的新问题进行求解,最终获得原调度问题的一个近似解.实验结果表明,通过该算法可以求得较好的结果,相对于其它启发式算法,该算法具有较好的稳定性.     

多机并行作业车间调度的混合粒子群算法

本文通过对多目标多机作业车间调度的研究提出了一个改进的结合启发式规则的粒子群算法,采用了依机器和工件排序的编码规则,两段式的表达形式,带启发式规则的调整,并结合聚类分析思想的保留策略,对此类问题提出了一个新的解决方法,并在文中通过一个仿真案例进行求解。     

求解一类并行多机调度问题的混合启发式算法

该文研究了一类工件具有不同释放时间的并行多机调度问题，调度目标为使总流程时间最小。针对该类调度问题具有强NP—hard的特点，首先构造了的一种启发式算法，该算法能够在很短的时间内找到次优解。由于通常启发式算法会随着问题规模的扩大导致求解的质量有所下降，结合遗传算法的全局搜索能力，提出了一种混合启发式算法进一步改善解的质量。仿真结果表明该算法很好地结合了启发式算法和遗传算法的特点，能够在较短的时间内求解较大规模的调度问题，算法的计算量小，鲁棒性好。     

冷轧生产调度模型及算法

针对冷轧生产线调度问题的复杂性, 将该问题规划为拼卷优化和轧制批量计划编制两个部分. 将拼卷优化问题归结为一个多容器装箱问题, 采用一种新的智能搜索算法——离散微分进化 (DDE) 对该问题进行求解; 对于轧制批量计划编制建立了一种特殊的双旅行商问题模型, 采用基于进化策略和邻域搜索的混合启发式方法求解模型. 最后通过上海宝钢生产实际数据对所提方法进行了试验, 试验结果显示本文给出的生产调度方法是有效的.     

应用离散事件系统控制理论求解生产调度的新方法

众所周知, 生产调度问题属组合优化问题, 一般来说不存在求得精确最优解的多项式算法. 因此, 对于大规 模调度问题, 人们应用启发式算法和元启发式算法以企求得满意解. 在实际的应用中, 许多工业过程需要满足严格 的工艺约束. 对于这类过程的调度问题, 很难应用启发式算法和元启发式算法, 因为这些方法难于保证所求得调度 的可行性. 为了解决这一问题, 本文以半导体芯片制造中组合设备的调度问题作为例子, 介绍了一种基于离散事件 系统控制理论的生产调度新方法. 利用Petri网建模, 任何违反约束的状态均被描述为非法状态, 而使非法状态出现 的调度则是不可行调度. 通过可行调度的存在性分析, 该方法获得可行解空间并将调度问题转化为连续优化问题, 从而可以有效求解. 并且指出, 该方法可以应用于其他应用领域.     

自适应超启发式遗传算法求解随机型生产调度问题

不确定型车间作业调度问题是由确定型车间作业调度问题转化而来的一个随机规划问题.针对目前求解SJSSP问题的启发式算法存在的一些局限,利用目标函数理想最值的条件,以最大加工时间最小化的期望为目标函数,提出了自适应超启发式遗传算法(Adaptive Hyper-Heuristics genetic algorithms,AHHGA),解决此类问题.在上层利用目标函数理想最值的条件,对于不同的场景选用不同的启发式规则.在下层根据上层选择的启发式规则,构造可行解,然后搜索获取最优解.通过上下两层的协同搜索,确保在有限的搜索范围内,找到性能更为优良的解,与此同时,尽可能的减少运算时间.仿真分析表明,对于FT类基准问题,当加工时间服从正态分布时,本文提出算法较目前求解此类问题的同类方法的求解质量具有一定的改进.     

Determination of replenishment dates for restricted-storage,static demand,cyclic replenishment schedule

This study focuses on scheduling replenishment lots of multiple products in a warehouse with restricted storage space where the replenishment cycle time of each product is given and is an integer multiple of some basic period. Assuming that the warehouse replenishes at the beginning of some basic period, this study proposes a new heuristic that utilizes two simple procedures to generate a replenishment schedule that minimizes the maximum warehouse-space requirement. By including a re-optimization mechanism and a Boltzmann function, the proposed heuristic obtains solutions very close to the global optimum within a reasonable run time. Using randomly generated instances, this study shows that the proposed heuristic significantly outperforms a previously published heuristic.     

A fluid approach to large volume job shop scheduling

We consider large volume job shop scheduling problems, in which there is a fixed number of machines, a bounded number of activities per job, and a large number of jobs. In large volume job shops it makes sense to solve a fluid problem and to schedule the jobs in such a way as to track the fluid solution. There have been several papers which used this idea to propose approximate solutions which are asymptotically optimal as the volume increases. We survey some of these results here. In most of these papers it is assumed that the problem consists of many identical copies of a fixed set of jobs. Our contribution in this paper is to extend the results to the far more general situation in which the many jobs are all different. We propose a very simple heuristic which can schedule such problems. We discuss asymptotic optimality of this heuristic, under a wide range of previously unexplored situations. We provide a software package to explore the performance of our policy, and present extensive computational evidence for its effectiveness.     

在中学排课问题中实用的模拟退火算法应用

针对中学排课问题,提出了一种分阶段的模拟退火算法解决方案.中学排课问题难点主要在于如何解决课表中存在的大量冲突以及如何优化课表.初始化随机生成一张带有冲突的课表,经过算法第一阶段,人工干预异化解结构,使课表可行;算法第二阶段引导性的改变课表结构使课表满足通用的软约束条件;算法第三阶段采用启发式随机邻域异化操作,变异课表,产生更优解.为了满足实际生产环境中对课表多元化的需求,在UI界面中提供可以手动调节课表机制.经过实验发现,改进后的模拟退火算法在解决中学排课问题时收敛速度更快,运行效率更高,并且在迭代次数较少的情况下,也能产生可行解.     

A linear optimization approach to the heterogeneous r-cyclic hoist scheduling problem

The cyclic hoist scheduling problem is encountered in electroplating facilities, when mass production is required. This class of problems is a branch stemming from the Hoist Scheduling Problem (HSP) where automatic hoist is used for moving electroplates through chemical baths. A repetitive sequence of moves is searched for the hoist in cyclic schedule. To minimize the cycle time of r different part-jobs, we propose a linear optimization approach. An illustrative example is given in order to show some feedback of our exact solving method. Afterward, two comparisons are presented: firstly, between a two 1-cycle homogenous schedule and a 2-cycle heterogeneous part-job and secondly, between 2-cycle and 4-cycle heterogeneous part-job. These comparisons show how, by considering r-cyclic scheduling, we can optimize the cycle length considerably and then the throughput rate of the electroplating line.     

单一产品复杂装配线启发式平衡排产方法

提出了一种基于Excel的单一产品复杂装配线启发式平衡排产方法。给出了基于Excel的单一产品复杂装配线启发式平衡排产方法的总体技术方案;阐述了该方法中的五个关键技术,包括将装配优先图映射为工作表,工序后接数及阶位值计算,工序排序,装配线平衡,装配线排产;通过案例分析验证了该方法的有效性。     

启发式会议调度算法的优化设计

本文介绍了一种用于办公自动化的会议调度软件的设计思想，给出了应用于该软件的会议调度算法－TR启发式算法，提供了有利于提高办公效率的修改更新会议调度表的自动化手段。     

Multihoist Cyclic Scheduling With Fixed Processing and Transfer Times

In this paper, we study the no-wait multihoist cyclic scheduling problem, in which the processing times in the tanks and the transfer times between tanks are constant parameters, and develop a polynomial optimal solution to minimize the production cycle length. We first analyze the problem with a fixed cycle length and identify a group of hoist assignment constraints based on the positions of and the relationships among the part moves in the cycle. We show that the feasibility of the hoist scheduling problem with fixed cycle length is consistent with the feasibility of this group of constraints which can be solved efficiently. We then identify all of the special values of the cycle length at which the feasibility property of the problem may change. Finally, the whole problem is solved optimally by considering the fixed-cycle-length problems at these special values. Note to Practitioners-Automated electroplating lines are commonly used in the production of many products, such as printed-circuit boards. The productivity of these systems depends heavily on effective scheduling of the material handling hoists that move the products between the processing tanks. This paper studies the hoist scheduling problem in systems where the processing times in the tanks and the intertank move times are fixed parameters. An efficient optimal algorithm is developed to solve the problem with any number of hoists. The resulting schedule can be programmed as programmable logic controller codes to directly control the hoist operations. The algorithm can also be used to develop heuristic solutions for multihoist scheduling in systems where the processing times may vary in given intervals.     

A two stage heuristic algorithm for the integrated aircraft and crew schedule recovery problems

Airline disruptions incurred huge cost for airlines and serious inconvenience for travelers. In this paper, we study the integrated aircraft and crew schedule recovery problem. A two stage heuristic algorithm for the integrated recovery problem is proposed. In the first stage, the integrated aircraft recovery and flight-rescheduling model with partial crew consideration is built. This model is based on the traditional multi-commodity network model for the aircraft schedule recovery problem. The objective of this model also includes minimization of the original crew connection disruption. In the second stage, the integrated crew schedule recovery and flight re-scheduling model with partial aircraft consideration is built. We proposed a new multi-commodity model for the crew schedule recovery. The main advantage of such model is that it is much more efficient to integrate the flight-scheduling and aircraft consideration. New constraints are incorporated to guarantee that the aircraft connections generated in the stage 1 are still feasible. Two stages are run iteratively until no improvement can be achieved. Experimental results show that our method can provide better recovery solutions compared with the benchmark algorithms.     

Hybrid discrete differential evolution algorithm for biobjective cyclic hoist scheduling with reentrance

Cyclic hoist scheduling problems in automated electroplating lines and surface processing shops attract many attentions and interests both from practitioners and researchers. In such systems, parts are transported from a workstation to another by a material handling hoist. The existing literature mainly addressed how to find an optimal cyclic schedule to minimize the cycle time that measures the productivity of the lines. The material handling cost is an important factor that needs to be considered in practice but seldom addressed in the literature. This study focuses on a biobjective cyclic hoist scheduling problem to minimize the cycle time and the material handling cost simultaneously. We consider the reentrant workstations that are usually encountered in real-life lines but inevitably make the part-flow more complicated. The problem is formulated as a biobjective linear programming model with a given hoist move sequence and transformed into finding a set of Pareto optimal hoist move sequences with respect to the bicriteria. To obtain the Pareto optimal or near-optimal front, a hybrid discrete differential evolution (DDE) algorithm is proposed. In this hybrid evolutional algorithm, the population is divided into several subpopulations according to the maximal work-in-process (WIP) level of the system and the sizes of subpopulations are dynamically adjusted to balance the exploration and exploitation of the search. We propose a constructive heuristic to generate initial subpopulations with different WIP levels, hybrid mutation and crossover operators, an evaluation method that can tackle infeasible individuals and a one-to-one greedy tabu selection method. Computational results on both benchmark instances and randomly generated instances show that our proposed hybrid DDE algorithm outperforms the basic DDE algorithm and can solve larger-size instances than the existing ε-constraint method.     

基于最大权值路径算法的DNA多序列比对方法

针对生物序列分析中的多序列比对问题,当输入数据量比较大时,人们提出了很多启发式的算法来改善计算速度和比对结果.提出了用于进行全局DNA多序列比对的一种方法:MWPAlign(maximum weighted path alignment).该算法把序列信息用de Bruijn图的形式表示,并将输入序列的信息记录在图的边上,这样,就将求调和序列的问题转化为求图的最大权值路径问题,使多序列比对问题的时间复杂度降低到几乎线性.实验结果显示:MWPAlign是可行的多序列比对算法,尤其对于变异率低于5.2%的大量序列数据,相对于CLUSTALW(cluster alignments weight),T-Coffee和HMMT(hidden Markov model training)有较好的比对结果和运算性能.