基于JIT配送的3PL运输协调调度问题建模与分析

近年来,随着第三方物流(Third Party Logistics,3PL)的日益成熟,其服务的专业性越来越高。相当数量的制造商们把产品的运输与配送外包给3PL以缩短订单处理的时间。本文研究Just-in-Time(JIT)背景下由3PL主导的供应链中3PL协调调度问题。3PL给出运输工具的出发、到达时间、可用的运载容量及相应的价格。制造商根据其生产调度和订单配送要求,有选择的使用3PL的运输资源,以最小的成本达JIT配送的目的。本文建立了该问题的数学模型,并证明了相应的计算复杂度。最后通过仿真实验验证计算复杂度。     

基于杂合遗传算法的工艺路线可变Job Shop调度研究

提出一种将遗传算法与启发式规则、模拟退火法等搜索方法结合在一起的杂合遗传算法,用于求解工艺路线可变的JobShop调度问题。通过对某双极型集成电路封装企业的JobShop调度仿真,结果表明算法是有效和可行的。     

Combinatorial Optimization in Real-Time Scheduling: Theory and Algorithms

Real-time computer systems are essential for many applications, such as robot control, avionics, medical instrumentation, manufacturing, etc. The correctness of the system depends on the temporal correctness as well as the functional correctness of the task executions. In order to assure temporal correctness it is necessary that the resources be scheduled to meet the temporal requirements of applications. When we consider the problem of nonpreemptive scheduling of a set of tasks in a processor for which no feasible solution exists, some tasks may have to be rejected so that a schedule can be generated for the rest. In this paper, we consider the problem of generating an optimal schedule such that the number of rejected tasks is minimized, and then the finish time is minimized for the accepted tasks. We propose to use an analytic approach to solve this problem. We first discuss the super sequence based technique which was originally proposed for reducing the search space in testing the feasibility of a task set. Then we show by the Conformation theorem that the super sequence constructed from the task set also provides a valid and reduced search space for the optimization problem. While the complexity of our scheduling algorithm in the worst case remains exponential, our simulation results show that the cost is reasonable for the average case.     

基于物联网的在线、智能调度方法的相关思考

物联网的飞速发展给生产调度系统带来了前所未有的机遇和挑战,数据的多源异构和连续涌入性、信息的透明性以及人、物料、设备、生产过程、产品等众多对象呈现出的连续动态存在性,这些新特征导致传统的调度优化方法难以适用。在已有研究的基础上,总结了物联网、调度优化方法以及基于情景的建模方法的研究现状和存在的问题,分析基于物联网的在线智能调度涉及到的问题及其特征,并提出其中的关键科学问题是基于情景的在线建模方法;提出该问题未来的研究目标为:针对物联网环境下调度对象状态的动态连续变化性,提供一种在线实时的智能优化调度方法,以最终实现调度优化过程的连续性以及调度优化决策的科学性、有效性和实用性;并详细阐述了未来关于基于情景的建模方法、基于情景的模型实时求解方法和基于情景的在线调度决策支持方法三方面的研究内容,为后续的深入研究做前期的思考和探索。     

Minimization of passenger takeoff and landing risk in offshore helicopter transportation: Models,approaches and analysis

Offshore petroleum industry uses helicopters to transport the employees to and from installations. Takeoff and landing represent a substantial part of the flight risks for passengers. In this paper, we propose and analyze approaches to create a safe flight schedule to perform pickup of employees by several independent flights. Two scenarios are considered. Under the non-split scenario, exactly one visit is allowed to each installation. Under the split scenario, the pickup demand of an installation can be split between several flights. Interesting links between our problem and other problems of combinatorial optimization, e.g., parallel machine scheduling and bin-packing are established. We provide worst-case analysis of the performance of some of our algorithms and report the results of computational experiments conducted on randomly generated instances based on the real sets of installations in the oil fields on the Norwegian continental shelf. This paper is the first attempt to handle takeoff and landing risk in a flight schedule that consists of several flights and lays ground for the study on more advanced and practically relevant models.     

The Effects of Multitasking on Operations Scheduling

This study considers a typical scheduling environment that is influenced by the behavioral phenomenon of multitasking. Under multitasking, the processing of a selected job suffers from interruption by other jobs that are available but unfinished. This situation arises in a wide variety of applications; for example, administration, manufacturing, and process and project management. Several classical solution methods for scheduling problems no longer apply in the presence of multitasking. The solvability of any scheduling problem under multitasking is no easier than that of the corresponding classical problem. We develop optimal algorithms for some fundamental and practical single machine scheduling problems with multitasking. For other problems, we show that they are computationally intractable, even though in some cases the corresponding problem in classical scheduling is efficiently solvable. We also study the cost increase and value gained due to multitasking. This analysis informs companies about how much it would be worthwhile to invest in measures to reduce or encourage multitasking.     

Managing Logistics in Regional Banknote Supply Chain Under Security Concerns

We study the logistics problem faced by Regional Branches (RBs) of a central bank in managing the currency supply under security concerns. While making banknote supply decisions to Sub‐Branches (SBs), the management of RB must achieve two goals simultaneously: (i) guarantee that each SB has sufficient inventories of all denominations of banknotes to satisfy the demands from all commercial banks within its service area, and (ii) control the annual spending on this banknote supply operation. Due to security concerns, the following methods are implemented in the process of transporting banknotes: (i) the capacity of a cash truck is limited by the total face value (instead of the physical space) of banknotes, and (ii) empty decoy trucks are deployed along with the trucks filled with banknotes. After deriving a polynomial‐time strategy to guarantee an optimal solution for the special Bin‐Packing Problem faced in this study, we provide an exact formulation for the RB's supply planning problem. We also propose several polynomial‐time algorithms for deriving either optimal or near‐optimal solutions for the problem under different settings. Using the weekly demand data obtained from the central bank, we verify the performance of our algorithms, and analyze the impacts of changes in these features and in the fleet capacity on the total cost incurred by an RB under various scenarios.     

多项目人力资源调度实证研究

针对某公寓大修项目,建立有关人力资源约束下的多项目进度管理问题混合整数规划模型。其中考虑了多种约束,如项目对人员能力、水平的不同要求,而人员又具有多种能力及水平;目标为满足约束的条件下总成本最小化,其中包含按时间计费的工资,和福利等的固定费用。为了简化计算,采用列生成法把复杂的多项目模型分解为一个主问题和多个子问题并协调主问题和子问题求解。同时由于子问题的复杂性难以精确求解,采用启发式算法求解:首先由基于优先原则的启发式方法给出问题的初始解,再由遗传算法寻优。最后通过该实际案例的应用,表明此方法能够快速有效的解决实际问题,给决策者提供信息,帮助指导实践。     

Integrated scheduling and inventory management of an oil products distribution system

The oil supply chain is facing new challenges due to emerging issues such as new alternative energy sources, oil sources scarcity, and price variability with high impact on demand and production and profit margins reduction. Additionally, the existence of large, complex and world wide spread businesses implies a complex system to be managed where distribution can be seen as one of the key areas that needs to be efficiently and effectively managed. Different types of distribution modes characterize the oil supply chain where the pipeline mode is one of the most complex to operate when having multiproduct characteristics. This paper addresses the planning of a generic oil derivatives transportation system characterized by a multiproduct pipeline that connects a single refinery to a storage tank farm. Two alternative mixed integer linear programming models (MILP) that aim to attain a set of planning objectives such as fulfilling costumers’ demands (which is mandatory) while minimizing the medium flow rate are developed. Additionally, final inventory levels are avoided to be excessively low. A real world scenario of a Portuguese company is used to validate and compare the two alternative MILP models developed in this paper.     

Optimum common cycle for scheduling a single-machine multiproduct system with a budgetary constraint

This paper deals with the single machine multi-product lot size scheduling problem, and has two objectives. The first objective is to minimize the maximum aggregate inventory for the common cycle (CC) scheduling policy. A simple and easy-to-apply rule has been developed which determines the optimal production sequence that achieves this objective. The second objective is to find an optimal common cycle for minimizing the average production and inventory costs per unit time, subject to a given budgetary constraint. A method has been presented that achieves this objective