共查询到18条相似文献,搜索用时 93 毫秒
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在处理时间不断恶化的情况下,针对插入多个机器维护阶段(RMAs)和考虑交货期安排的单机调度问题展开研究,目标是最小化提前和拖期惩罚。产品加工过程中,在处理工件之前插入多个RMAs可以降低恶化现象从而恢复机器的生产效率,目的是同时找到最优序列、最优松弛时间和RMAs的最优位置以使提前和拖期惩罚最小。根据问题的特点,提出了相关的性质和定理,通过证明得出了最优的松弛时间。最后,证明了该问题在多项式时间内是可解的。 相似文献
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研究了两个工件集合竞争在一台批处理机上加工的调度问题, 其中每个集合的工件具有一个共同的释放时间.批处理机可以同时加工多个工件作为一批, 每批的加工时间为该批工件中加工时间的最大值.基于两类释放时间的大小, 针对无界批处理机上最小化一个集合工件的最大完工时间、最大延迟以及总完工时间, 使得另一个集合工件的最大完工时间不超过给定上界问题, 分别给出了最优求解方法.针对有界批处理机上最小化一个集合工件的最大完工时间, 使得另一个集合工件的最大完工时间不超过给定上界问题, 证明为一般意义NP--!难问题, 并给出伪多项式时间最优求解方法. 相似文献
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针对研究了两代理情形下的单机排序问题,考虑两类问题:一是在误工工件个数不超过一个给定值的情况下使得总误工最小,另一个是代理[A]的工件加工时间和权重满足反一致关系时,在误工工件个数不超过一个给定值的情况下使得总加权完工时间之和最小。对于这两类问题采用动态规划方法分别给出最优性质和相应的拟多项式时间算法。 相似文献
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以包头某钢铁线材企业实际调度问题为背景,针对带组换装时间的单机提前/拖期调度问题,建立了混合整数线性规划模型.根据模型的特点,将该问题的求解分为最优排序变量的确定和最优开工时间的确定两个层次.由于该问题是NP难的,提出了一种基于遗传算法和线性规划相结合的GA/LP算法.在算法中,利用GA在外层搜索遍历二元变量空间来优化工件排序;在内层则利用LP来确定满足约束条件的最优连续解.为了提高算法寻优性能,降低算法运行时间,提出了一种基于问题特征的种群初始化方法.最后,针对三种交叉算子在随机问题上进行了测试,实验结果表明,该算法能够有效求解问题. 相似文献
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T. C. E. Cheng L. Y. Kang C. T. Ng 《International Transactions in Operational Research》2005,12(3):355-366
We study the problem of scheduling jobs whose processing times are decreasing functions of their starting times. We consider the case of a single machine and a common decreasing rate for the processing times. The problem is to determine an optimal combination of the due date and schedule so as to minimize the sum of due date, earliness and tardiness penalties. We give an O(n log n) time algorithm to solve this problem. 相似文献
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A Stronger Complexity Result for the Single Machine Multi-Operation Jobs Scheduling Problem to Minimize the Number of Tardy Jobs 总被引:1,自引:0,他引:1
We consider the single machine multi-operation jobs scheduling problem to minimize the number of tardy jobs. Each job consists of several operations that belong to different families. In a schedule, each family of job operations may be processed in batches with each batch incurring a setup time. A job completes when all of its operations have been processed. The objective is to minimize the number of tardy jobs. In the literature, this problem has been proved to be strongly NP-hard for arbitrary due-dates. We show in this paper that the problem remains strongly NP-hard even when the due-dates are common and all jobs have the same processing time. 相似文献
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有到达时间的多处理器混合流水车间调度问题在实时机器视觉系统等领域有广泛的应用.这一问题是NP-困难的.鉴于以上原因,给出一种遗传算法.对不同的交叉算子和变异算子以及涉及的参数的不同取值进行试验,并对试验的结果进行分析和讨论,从而给出最好的参数组合. 相似文献
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In this article, we consider a single machine scheduling problem with a time-dependent learning effect and deteriorating jobs. By the effects of time-dependent learning and deterioration, we mean that the job processing time is defined by a function of its starting time and total normal processing time of jobs in front of it in the sequence. The objective is to determine an optimal schedule so as to minimize the total completion time. This problem remains open for the case of ?1?a?0, where a denotes the learning index; we show that an optimal schedule of the problem is V-shaped with respect to job normal processing times. Three heuristic algorithms utilising the V-shaped property are proposed, and computational experiments show that the last heuristic algorithm performs effectively and efficiently in obtaining near-optimal solutions. 相似文献
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本文研究的连续型批处理机调度问题, 是在钢铁工业管坯的加热过程中提出来的. 工件带有释放时间和工期, 工件进入和离开机器是按周期依次进行的. 本文针对单机连续型批调度问题中工件释放时间和工期同序的情况, 分析了极小化最大拖期和拖期工件数等问题的计算复杂性, 证明了两类问题都是强NP-难的. 对于工件的释放时间和加工时间、工期都同序的特殊情况, 分别给出了能够获得对应问题的最优解的多项式算法. 相似文献