飞机移动生产线作业调度问题的启发式算法

飞机移动生产线作业调度问题是一种具有特殊约束的项目调度问题。综合分析了飞机移动生产线的作业顺序关序、资源约束、空间限制的多重特点,建立了以最小装配完工时间为目标的模型。将问题分为确定作业的优先顺序和选择作业人数的两个阶段进行决策,设计了由不同规则组合成27种启发式方法。通过比较启发式方法在250个测试问题集的表现,确定最有效的解决此问题的方法。     

Research on Fuzzy Decision of Resources Selection in Job-shop Scheduling for a One-of-a-Kind and Order-Oriented Production System

In a one-of-a-kind and order-oriented production corporation, job shop scheduling plays an important role in the production planning system and production process control. Since resource selection in job shop scheduling directly influences the qualities and due dates of products and production cost, it is indispensable to take resource selection into account during job shop scheduling. By analyzing the relative characteristics of resources, an approach of fuzzy decision is proposed for resource selection. Finally, issues in the application of the approach are discussed.     

基于增强学习的半导体测试调度研究

采用Sarsa(λ,k)学习算法求解、产品、测试机、测试工具包、使能器部件对应关系非常复杂的半导体测试调度问题.针对测试调度,通过定义系统状态的表示方式、构造行为和报酬函数把调度问题转化为增强学习问题,并把Sarsa(λ,k)算法和梯度下降径向基神经网络函数泛化器结合使用.实验验证了Sarsa(λ,k)算法解决半导体测试调度问题的有效性.Sarsa(λ,k)算法通过反复解决调度问题来调整调度策略,能克服单个行为策略短视的缺点,综合利用各个行为策略的优点,从而找到较优的调度方案.     

工件带到达时间并具有成组约束的车间排序算法

针对模具制造过程的特点,在工件不同时到达的情况下,研究了前阶段带有成组约束的两阶段柔性同序加工车间的调度问题,建立了目标函数为最小化最大完成时间的调度数学模型．基于Potts的RJ’算法提出解决此类问题的启发式算法,并将该算法应用到轮胎模具企业的生产实例中,通过仿真说明数学模型和求解方法的可靠性和有效性．     

一类多资源调度问题的优化算法

若调度系统中的作业或任务需要一个或多个资源共同完成, 则这一类调度问题被称为多资源（或多处理机）调度问题。本文针对Jobshop中的这一调度问题,提出了基于遗传的优化调度算法,并用实例证实了该算法的有效性。     

关键链上可被部分替代的受限资源动态调度

关键链上受限资源的优化调度,能有效提高系统运作效率,是关键链项目管理的重要研究方向之一.但现有研究主要针对资源能否更新,较少考虑资源的可替代性.针对此,研究了关键链上可被部分替代的受限资源调度问题,以达到提高资源利用率、降低成本等目的.采用α/β/γ三元组方法,将研究的问题描述为以最小化滞后时间和为目标,具有机器适用限制的并行异速机调度问题,并建立对应的数学模型;运用混合重调度策略和改进粒子群算法进行了算法设计;设计了仿真算例,并通过算法比较表明该方法在求解结果和问题求解规模上显著优于传统PSO、GA算法.     

新型集装箱码头堆场混合装卸计划方法研究

对一种新型的集装箱装卸系统在给定集装箱装卸作业任务前提的单装/卸和装卸混合模式调度问题进行了探索研究.针对这种自动化码头装卸作业的特征,将此集装箱装卸作业调度问题定义为特殊的三阶段柔性Job shop调度问题,以完成给定装卸作业任务的最短时间为优化目标,设计了以低架桥分配小车作为调度中心,对这一三阶段集成优化调度问题求...     

一类资源负荷均衡问题的优化调度算法

针对一类n个独立任务在m个不完全同等的处理机上处理,使处理机的最大负荷为最小的非抢先调度问题,提出了一种启发式算法－－最小平衡算法,并分析了它的时间复杂性,在此基础上,又将最小平衡算法和遗传算法结合起来,提出了基于遗传的最小平衡算法,并用实例证实了该算法的有效性。     

基于分区法的2-RGV调度问题的模型和算法

以某救灾物资自动化立体仓库为背景,研究了出库过程中的2-RGV调度问题.为避免运行于直线轨道上的两辆穿梭车发生碰撞,将存取系统划分为不重叠的两个区域,并将两个区域内的运送分别分配给两辆穿梭车.建立了基于区域划分的2-RGV调度问题的混合整数线性规划模型,目标是最小化所有物料的总出库时间.提出了一个混合遗传算法求解该问题,并采用包含穿梭车顺序、穿梭车分配及出库站分配的染色体编码方式.算例试验显示提出的模型和算法能够有效求解该问题.     

基于HTCPN的分段生产物流系统建模与仿真:案例研究

船舶分段生产物流系统是一个典型的资源约束下的多项目调度复杂系统。根据S企业分段生产流程和资源的配置情况,利用层次赋时有色佩特里网(HTCP-net),结合提出的一种适合多项目调度的启发式规则,建立了分段生产物流系统模型。通过CPN tools进行仿真,验证了模型的正确性,发现了流程中的瓶颈,提出了合理的资源配置数量,通过对比证明了本启发式规则较适合船厂的多项目调度。文中的研究方法对复杂的造船流程的建模、仿真和分析具有一定参考价值。     

考虑班种约束的呼叫中心排班优化模型与算法

一些呼叫中心设置早班、晚班和两段班班种;排班时规定员工周内同班种的班次当班,并且限制两段班当班员工占比。构建该实际情景的坐席人员排班问题整数规划模型。鉴于问题难解性,首先通过问题结构层次分解,以及对班种与班次覆盖区段人力需求量化指标的表征刻画,提出启发式算法生成解方案;然后采用基于模拟退火机制的邻域搜索算法改善解方案。计算实验表明整数规划模型适于求解小规模排班问题最优解,而上述两阶段优化算法能够获得大规模问题优化解。研究表明,在优化人力成本情况下可兼顾坐席人员工作时间高规律性。     

序时多指标决策的夹角模糊优选法

针对有时序的多指标决策问题,提出一种新的决策方法－夹角模糊优选法,并给出该方法的原理与步骤,最后以实例说明此方法的应用,为决策者提供了一条新思路。     

等待时间受限的并行批处理调度问题研究

研究了任务等待时间受限的并行批处理调度问题,建立它的约束规划模型,设计调度任务的“小s大S”规则,该调度规则最重要的参数为临界队长参数和考虑受限时间的紧急时间参数.基于该规则进行模拟实验,用RSM响应面方法进行参数优化,将模拟结果同约束规划模型(CP方法)在CPLEX环境下求得的解进行比较,分析“小s大S”规则的性能和效果.     

A Disjunctive Model for Scheduling in a Manufacturing and Packing Facility with Intermediate Storage

The problem considered in this paper deals with the short term scheduling of a two stage continuous process with intermediate storage tanks. The major scheduling decisions in this problem are: a) the assignment of orders to various storage tanks; b) the sequence of orders in each unit; c) the timing of various operations in different stages. The problem is highly combinatorial in nature. The major challenge is to develop strong integer programming formulations and to devise efficient solution techniques. An initial model is presented in the form of a disjunctive program which is later transformed to a Mixed Integer Linear Programming (MILP) problem. A number of example problems are solved which highlight the limitations of this model as the number of orders increases. A heuristic based on partial preordering is considered which solves industrial sized problems very quickly. The objective function values for the heuristic solutions are within 7% of the optimal values.     

A robust scheduling for the multi-mode project scheduling problem with a given deadline under uncertainty of activity duration

The problem of this paper deals with the multi-mode project scheduling problem under uncertainty of activity duration where only the renewable resources are taken into account and a given deadline has to be met at the cost of recruiting additional resources. A heuristic algorithm is employed to solve this problem, and to maintain the robustness of the baseline schedule, the concept of critical chain project management (CCPM) is applied in which a new definition to resource buffer is considered. A simulation methodology is used to determine the size and location of resource buffers in the schedules in which three different buffer sizes and three different uncertainty levels are considered. Results and analysis of the simulation outcomes illustrate that resource buffers are useful and should be simulated by the CCPM schedules, as they help to decrease the total duration of the project during implementation and meet the deadline of the project with more assurance.     

Optimal scheduling for sequentially connected cluster tools with dual-armed robots and a single input and output module

We examine a cyclic scheduling problem of sequentially connected cluster tools with a single input and output module, which includes multi-cluster tools and linear cluster tools. Every component tool has a dual-armed robot, and chambers are parallelised for a long process step. An intermediate buffer between each pair of adjacent component tools has a limited capacity, and all processed wafers should return to the input and output module. To examine the scheduling problem, we first compute workloads of the process steps and robots to obtain a lower bound on the tool cycle time. We then identify a rule of assigning the chambers to the process steps that makes the tool cycle time independent of the order of using the parallel chambers. We also propose a simple robot task sequence which is modified from the well-known swap sequence for each component tool. We prove that the modified swap sequence is optimal when one of the process steps, not a robot, is the bottleneck. We also present a scheduling strategy which controls robot task timings to deal with interference of wafer flows between each pair of adjacent component tools. Finally, we perform numerical experiments to show the performance of the proposed sequence.     

On a mixed zero-one separable non-linear approach for water irrigation scheduling

We present a mixed zero-one separable non-linear approach to the optimization of the management of water resources used for agricultural irrigation purposes. It provides dynamic planning of the daily irrigation scheduling for a given land area by considering the irrigation network topography, water flow conditions and logistical operation constraints in order to optimize the use of water stored in a reservoir. We present a mixed zero-one separable non-linear program and a solution procedure that iteratively solves a mixed zero-one linear approximation of the model. We are not aware of any previous attempt to solve large-scale mixed zero-one separable non-linear programs of this kind. Some computational experiences on a large-scale real-life problem are reported.     

A Posteriori Error Estimates of Lowest Order Raviart-Thomas Mixed Finite Element Methods for Bilinear Optimal Control Problems

A Raviart-Thomas mixed finite element discretization for general bilinear optimal control problems is discussed. The state and co-state are approximated by lowest order Raviart-Thomas mixed finite element spaces, and the control is discretized by piecewise constant functions. A posteriori error estimates are derived for both the coupled state and the control solutions, and the error estimators can be used to construct more efficient adaptive finite element approximations for bilinear optimal control problems. An adaptive algorithm to guide the mesh refinement is also provided. Finally, we present a numerical example to demonstrate our theoretical results.     

三维Stokes方程的一个低阶非协调混合元格式收敛性分析

本文对三维Stokes方程提出一个新的低阶稳定的非协调混合元格式。首先,将该低阶Crouzeix-Raviart型非协调矩形元用于逼近速度空间,压力空间选取分片常数进行逼近,然后得到了关于速度能量模,压力和速度L2-模的最优误差估计。最后,数值算例验证了方法的有效性,并支持了本文的理论分析。     

Unified Relaxation Spectrum for Polymers of Multiple Scales Based upon a Fuzzy Constraint Method and Non-Equilibrium Statistical Thermodynamics

The molecular relaxation mechanisms of polymers withmulti-scale units of motion in glassy, rubbery and melt states areproposed based upon a fuzzy constraint method and non-equilibriumstatistical thermodynamics. The entanglement effects due to cohesiveforce and steric hindrance are expressed quantitatively in terms of amembership function. The micro-Brownian motion of a polymer chain isgoverned by the Langevin equation, which accounts for viscous force,nonuniform tension, entanglement constraint force and random force.Perturbation solutions have been established for different time and sizescales. The solutions account for the effects of both intramolecular andintermolecular interactions in the relaxation process. The unifiedrelaxation spectrum over many orders of time scale is a naturalconsequence of macromolecular structure, which satisfies thetime-temperature equivalence in the form of the Arrhenius equation atlow and high temperatures and in the form of the WLF equation near theglass transition temperature. The barrier model, the normal mode theory,the retraction and reptation theories can be taken as special casescorresponding to different scales.