多目的批量过程的受影响批次再调度算法

为解决多目的批量过程调度受延迟扰动的问题,提出了综合考虑新调度质量和稳定性的受影响批次再调度ABR算法,根据状态任务网STN所定义的工艺过程将受到延迟影响的所有批次向后移动最小可能值。仿真算例表明,ARB再调度算法在完成时间指标和开始时间总延迟指标上均优于现有的右移再调度法RSR。     

OBS网络中多重主动重调度算法

信道调度算法是光突发交换（OBS）网络的关键技术之一。在主动重调度算法的基础上,提出了一种新的多重主动重调度算法,通过搜索并重调度数据信道上所有能进行重调度的突发,使多个突发重调度后产生的间隔尽量小,从而降低突发丢失率。     

云制造环境下的动态调度

在云制造环境下, 制造资源和制造能力以服务的形式封装起来, 不同的任务通过云端汇集到云平台并通过合适的调度给每个任务分配相应的服务. 由于任务在执行的过程中的不确定性, 会在某个时刻遇到突发状况从而导致对余下任务的重调度问题. 因此, 针对该问题, 考虑到云制造环境下任务的复杂性和多样性会导致在合理的时间段内很难找到最优解, 以所有任务的最大完成时间为优化目标, 提出了一种以改进的遗传算法与邻域搜索技术相结合的元启发式算法, 旨在解决云制造环境下由于任务和资源服务等的不确定性导致的重调度问题. 实验结果表明,本文所提出的算法能够很好地解决动态调度过程中的重调度问题, 并可以快速地获取最优解.     

重庆港骨干集装箱码头联动调度的动态模拟

多港口联合调度在我国还处于研究上的空白状态。考虑到港离港时间、满空箱量、泊位吨数等方面的因素,设计了重庆港多港口集装箱码头联动调度的原则和策略,建立了联动调度的数学模型,定义了目标函数和相应的约束条件,并实现了调度计划的动态模拟和仿真测试。     

Developing a dynamic rolling-horizon decision strategy for yard crane scheduling

As a hub for land and marine transportation, container terminals play an important role in global trade. In today’s competitive environment, container terminals should improve their service quality, i.e., effective space resource handling and equipment resource scheduling, for their prosperity or even survival. Although intensive researches were attempted on yard crane scheduling, the solutions from these approaches likely reached a local optimum, and thereafter a rational strategy towards global optimum was still lacking. Accordingly, it became an imperative to explore a rational strategy for this purpose. To resolve this problem, a novel dynamic rolling-horizon decision strategy was proposed for yard crane scheduling in this study. Initially, an integer programming model was established to minimize the total task delaying at blocks. Due to the computational scale with regard to the yard crane scheduling problem, a heuristic algorithm, along with a simulation model, was then applied. In this fashion, the simulation model was next investigated to alternate the periods and evaluate the task delaying. Subsequently, a genetic algorithm was employed to optimize the initial solutions generated. Consequently, computational experiments were used to illustrate the proposed strategy for yard crane scheduling and verify the effectiveness and efficiency of the proposed approach.     

Rescheduling Manufacturing Systems: A Framework of Strategies, Policies, and Methods

Many manufacturing facilities generate and update production schedules, which are plans that state when certain controllable activities (e.g., processing of jobs by resources) should take place. Production schedules help managers and supervisors coordinate activities to increase productivity and reduce operating costs. Because a manufacturing system is dynamic and unexpected events occur, rescheduling is necessary to update a production schedule when the state of the manufacturing system makes it infeasible. Rescheduling updates an existing production schedule in response to disruptions or other changes. Though many studies discuss rescheduling, there are no standard definitions or classification of the strategies, policies, and methods presented in the rescheduling literature. This paper presents definitions appropriate for most applications of rescheduling manufacturing systems and describes a framework for understanding rescheduling strategies, policies, and methods. This framework is based on a wide variety of experimental and practical approaches that have been described in the rescheduling literature. The paper also discusses studies that show how rescheduling affects the performance of a manufacturing system, and it concludes with a discussion of how understanding rescheduling can bring closer some aspects of scheduling theory and practice.     

Robust berth scheduling at marine container terminals via hierarchical optimization

In this paper, we present a mathematical model and a solution approach for the discrete berth scheduling problem, where vessel arrival and handling times are not known with certainty. The proposed model provides a robust berth schedule by minimizing the average and the range of the total service times required for serving all vessels at a marine container terminal. Particularly, a bi-objective optimization problem is formulated such that each of the two objective functions contains another optimization problem in its definition. A heuristic algorithm is proposed to solve the resulting robust berth scheduling problem. Simulation is utilized to evaluate the proposed berth scheduling policy as well as to compare it to three vessel service policies usually adopted in practice for scheduling under uncertainty.     

Yard crane scheduling in a container terminal for the trade-off between efficiency and energy consumption

Green transportation has recently been the focus of the transportation industry to sustain the development of global economy. Container terminals are key nodes in the global transportation network and energy-saving is a main goal for them. Yard crane (YC), as one type of handling equipment, plays an important role in the service efficiency and energy-saving of container terminals. However, traditional methods of YC scheduling solely aim to improve the efficiency of container terminals and do not refer to energy-saving. Therefore, it is imperative to seek an appropriate approach for YC scheduling that considers the trade-off between efficiency and energy consumption. In this paper, the YC scheduling problem is firstly converted into a vehicle routing problem with soft time windows (VRPSTW). This problem is formulated as a mixed integer programming (MIP) model, whose two objectives minimize the total completion delay of all task groups and the total energy consumption of all YCs. Subsequently, an integrated simulation optimization method is developed for solving the problem, where the simulation is designed for evaluating solutions and the optimization algorithm is designed for exploring the solution space. The optimization algorithm integrates the genetic algorithm (GA) and the particle swarm optimization (PSO) algorithm, where the GA is used for global search and the PSO is used for local search. Finally, computational experiments are conducted to validate the performance of the proposed method.     

Yard crane scheduling problem in a container terminal considering risk caused by uncertainty

In a container terminal, the arriving times and handling volumes of the vessels are uncertain. The arriving times of the external trucks and the number of containers which are needed to be brought into or retrieved from a container terminal by external trucks within a period are also uncertain. Yard crane (YC) scheduling is under uncertainty. This paper addresses a YC scheduling problem with uncertainty of the task groups' arriving times and handling volumes. We do not only optimize the efficiency of YC operations, but also optimize the extra loss caused by uncertainty for reducing risk of adjusting schedule as the result of the task groups' arriving times and handling volumes deviating from their plan. A mathematical model is proposed for optimizing the total delay to the estimated ending time of all task groups without uncertainty and the extra loss under all uncertain scenarios. Furthermore, a GA-based framework combined with three-stage algorithm is proposed to solve the problem. Finally, the proposed mathematical model and approach are validated by numerical experiments.     

自动化码头双小车岸桥与AGV协调调度问题研究

为研究自动化集装箱码头中自动导引运输车（Automated Guided Vehicle，AGV）与双小车岸桥（Double-Trolley Quay Crane，QC）的协调调度问题，考虑双小车岸桥中转平台及其容量限制，并以双小车岸桥门架小车时间窗为约束，建立以集装箱任务最大完工时间最小化为目标的混合整数规划模型。设计启发式算法，由中转平台的容量求得岸桥门架小车操作集装箱任务的时间窗，并采用遗传算法进行求解，给出相应的AGV调度优化方案，解决两大设备的协调调度问题。最后，以10组实验为例，比较了遗传算法与粒子群算法的优化结果。结果表明两种算法一致，且基于遗传算法的模型求解收敛速度更快，从而验证了该算法的可行性。     

基于李雅普诺夫优化的容器云队列在线任务和资源调度设计

为在保证任务服务质量（QoS）的条件下提高容器云资源利用率，提出一种基于李雅普诺夫的容器云队列任务和资源调度优化策略。首先，在云计算服务排队模型的基础上，通过李雅普诺夫函数分析任务队列长度的变化；然后，在任务QoS的约束下，构建资源功耗的最小化目标函数；最后，利用李雅普诺夫优化方法求解最小资源功耗目标函数，获得在线的任务和容器资源的优化调度策略，实现对任务和资源调度进行整体优化，从而保证任务的QoS并提高资源利用率。CloudSim仿真结果表明，所提的任务和资源调度策略在保证任务QoS的条件下能获得高的资源利用率，实现容器云在线任务和资源优化调度，并且为基于排队模型的云计算任务和资源整体优化提供必要的参考。     

A simulation-based Genetic Algorithm approach for the quay crane scheduling under uncertainty

The fast-paced growth in containerized trade market sparks the need for efficient operations at seaport container terminals. One major determinant of terminal efficiency is the productivity of Quay Cranes (QC) resulting from QC scheduling. This paper focuses on the QC Scheduling Problem (QCSP). The objective is to minimize vessel handling time while considering the entire container handling process involving both seaside operations and container transfer operations, taking place between the quay and the stacking yard. A stochastic mixed integer programming model is proposed, and a simulation-based Genetic Algorithm (GA) is applied to construct QC schedules that account for the dynamics and the uncertainty inherent to container handling process. Computational experiment shows satisfactory results of the proposed algorithm and stresses the importance of simulation to obtain more reliable estimates of QC schedule performance.     

自动化码头AGV充电与作业的集成调度研究

为了提高自动化集装箱码头AGV（Automated Guided Vehicle）的作业效率,根据采用电力驱动的AGV作业时的充电需求和运输过程的特性,考虑了垂岸式集装箱堆场布局和AGV充电过程对实际作业的影响,以最大化AGV充电利用率、最小化最末任务完成时间、最小化AGV空载时间为目标,以AGV充电后的续航能力等为约束条件,以遗传算法为研究方法,构建了考虑充电过程的自动化码头AGV作业的调度模型。通过算例分析,对比了遗传算法与混合整数规划算法的求解效果,分析了参与运输的AGV数量对运输时间的影响,也验证了遗传算法给出的调度方案的可信性。最后得出结论：针对该问题,遗传算法可以快速、高效地给出值得信赖的AGV调度方案。     

不确定环境下码头堆场设备集成调度优化

集装箱码头堆场设备调度优化中,对确定条件下的内集卡和场桥的联合调度研究较多,且没有考虑外集卡的随机到达情况。考虑内集卡和场桥作业过程中的不确定性因素,包括：内集卡行驶速度,场桥行走速度和作业时间,并考虑外集卡随机到达堆场对于内集卡调度作业的影响,构建了不确定因素条件下的堆场设备集成调度优化模型,其优化目标是在考虑外集卡随机到达的情况下,最优化堆场设备的作业时间。设计了求解模型的粒子群算法,并比较了一般确定性模型和考虑不确定因素优化模型的结果。算例结果表明,所建立的模型和算法能有效真实地反映不确定因素对集装箱码头堆场设备作业的影响。     

Filtered-beam-search-based algorithm for dynamic rescheduling in FMS

In the practical production process of a flexible manufacturing system (FMS), unexpected disturbances such as rush orders arrival and machine breakdown may inevitably render the existing schedule infeasible. This makes dynamic rescheduling necessary to respond to the disturbances and to improve the efficiency of the disturbed FMS. Compared with the static scheduling, the dynamic rescheduling relies on more effective and robust search approaches for its critical requirement of real-time optimal response. In this paper, a filtered-beam-search (FBS) -based heuristic algorithm is proposed to solve the dynamic rescheduling problem in a large and complicated job shop FMS environment with realistic disturbances. To enhance its performance, the proposed algorithm makes improvement in the local/global evaluation functions and the generation procedure of branches. With respect to a due date-based objective (weighted quadratic tardiness), computational experiments are studied to evaluate the performance of the proposed algorithm in comparison with those of other popular methods. The results show that the proposed FBS-based algorithm performs very well for dynamic rescheduling in terms of computational efficiency and solution quality.     

Integrating simulation and optimization to schedule loading operations in container terminals

In this paper, a simulation optimization method for scheduling loading operations in container terminals is developed. The method integrates the intelligent decision mechanism of optimization algorithm and evaluation function of simulation model, its procedures are: initializing container sequence according to certain dispatching rule, then improving the sequence through genetic algorithm, using simulation model to evaluate objective function of a given scheduling scheme. Meanwhile, a surrogate model based on neural network is designed to predict objective function and filter out potentially bad solutions, thus to decrease the times of running simulation model. Numerical tests show that simulation optimization method can solve the scheduling problem of container terminals efficiently. And the surrogate model can improve the computation efficiency of simulation optimization.     

结合价值密度和截止期的网格实时作业调度

在商业网格和云计算环境中,作业有到达时间、计算量、预算、截止期等参数,其中,预算是时间的函数。准确区分作业的重要性和紧迫性是作业调度系统的一个关键问题。综合利用这四个参数来定义作业的优先级,并提出基于价值密度和相对截止期的网格作业调度算法。分别对弱实时和强实时网格作业的调度进行仿真。仿真结果显示,所提出的调度算法的性能在两种情况下都优于所有对比算法的性能,且在强实时作业情况下优势更明显。     

Service scheduling and rescheduling in an applications integration framework

Grid technologies are evolving towards a service oriented architecture (SOA) and the traditional client/server architecture of heterogeneous computing (HC) can be transformed into a grid service oriented architecture. In this architecture, when more than one service fulfills the user request, a service which can make scheduling decisions is essential. A scheduling service has been proposed in a framework which achieves the dynamic deployment and scheduling of scientific and engineering applications. The framework treats all components (resource service and scheduler service) as WSRF-compliant services which support the applications integration with underlying native platform facilities and facilitate the construction of the hierarchical scheduling system. In order to enhance the system performance, we replace the MWL scheduling algorithm with an MCT algorithm and integrate a rescheduling mechanism in the framework. The experiments show that the MCT algorithm can achieve a smaller makespan and the rescheduling mechanism ensures the task execution even if an application is removed from the Resource Service.     

Minimizing Mean Completion Time in a Batch Processing System

We consider batch processing jobs to minimize the mean completion time. A batch processing machine can handle up to $B$ jobs simultaneously. Each job is represented by an arrival time and a processing time. Jobs processed in a batch have the same completion time, i.e., their common starting time plus the processing time of their longest job. For batch processing, non-preemptive scheduling is usually required and we discuss this case. The batch processing problem reduces to the ordinary uniprocessor system scheduling problem if $B=1$. We focus on the other extreme case $B=+\infty$. Even for this seemingly simple extreme case, we are able to show that the problem is NP-hard for the weighted version. In addition, we establish a polynomial time algorithm for a special case when there are only a constant number of job processing times. Finally, we give a polynomial time approximation scheme for the general case.     

Stochastic DAG scheduling using a Monte Carlo approach

In heterogeneous computing systems, there is a need for solutions that can cope with the unavoidable uncertainty in individual task execution times, when scheduling DAGs. When such uncertainties occur, static DAG scheduling approaches may suffer, and some rescheduling may be necessary. Assuming that the uncertainty in task execution times is modelled in a stochastic manner, we may be able to use this information to improve static DAG scheduling considerably. In this paper, a novel DAG scheduling approach is proposed to solve this stochastic scheduling problem, based on a Monte Carlo method. The approach is built on the top of a classic static DAG scheduling heuristic and evaluated through extensive simulation. Empirical results show that a significant improvement of average application performance can be achieved by the proposed approach at a reasonable execution time cost.