A reactive tabu search algorithm for the vehicle routing problem with simultaneous pickups and deliveries

The vehicle routing problem with pickups and deliveries (VRPPD) extends the vehicle routing problem (VRP) by allowing customers to both send and receive goods. The main difficulty of the problem is that the load of vehicles is fluctuating rather than decreasing as in the VRP. We design a reactive tabu search metaheuristic that can check feasibility of proposed moves quickly and reacts to repetitions to guide the search. Several new best solutions are found for benchmark problems.     

An investigation into the vehicle routing problem with time windows and link capacity constraints

In this work, we investigate a new, yet practical, variant of the vehicle routing problem called the vehicle routing problem with time windows and link capacity constraints (VRPTWLC). The problem considers new constraints imposed on road links with regard to vehicle passing tonnage, which is motivated by a business project with a Hong Kong transportation company that transports hazardous materials (hazmats) across the city and between Hong Kong and mainland China. In order to solve this computationally challenging problem, we develop a tabu search heuristic with an adaptive penalty mechanism (TSAP) to help manage the company's vehicle fleet. A new data set and its generation scheme are also presented to help validate our solutions. Extensive computational experiments are conducted, showing the effectiveness of the proposed solution approach.     

Scheduling to minimize stringer utilization for continuous annealing operations

In this paper we present a mathematical program and heuristic algorithms to schedule coils for the production operations in a copper (or steel) coil manufacturing industry. The processing facility uses continuous operations for processing (e.g., galvanizing and annealing) while the handling unit is a discrete coil. The ends of coils are “stitched” or welded together to enable continuous processing, and the joint is later sheared off to obtain the processed coils. Processing constraints impose restrictions on the compatibility between a pair of coils that are overcome by introducing a dummy coil called stringer, which is very expensive to a mill. This paper deals with modeling the sequencing/scheduling problem of coils on parallel non-identical machines to minimize stringer utilization. Both computational and practical experiences show the efficiency and effectiveness of the solution approaches. Implementing these methods in an actual coil annealing facility resulted in 65% reduction in stringer utilization.     

基于改进模糊遗传算法的混合车辆路径问题

本文建立了多配送中心、多车型、多产品的车辆路径问题的混合数学模型,提出了一种新的模糊遗传算法求解混合车辆路径问题,通过改进的模糊逻辑控制器实现交叉概率和变异概率的动态调整,以加快算法收敛速度并避免算法陷入局部最优解。采用标准算例进行对比,证明模糊遗传算法有较好的计算结果和计算效率,并用模糊遗传算法对混合车辆路径模型进行仿真测试,取得了理想的结果。     

基于需求预测的两级动态配送路径优化研究

针对传统响应式配送难以应对海量动态客户需求的困境,在此提出基于需求预测的两级动态配送路径优化方法。利用历史数据从需求预测、需求聚类和需求配额三个维度,处理电商物流配送过程中的动态需求;建立基于需求预测的单阶段和多阶段两级车辆配送路径优化模型,并针对问题特性利用分支定界算法与CW-禁忌搜索算法生成两个阶段的最优配送路径。最后结合实验案例对模型与算法的有效性进行验证,试验结果表明本文设计方法具有较好的动态场景适应度和客户响应能力。     

梯度相关的无线传感器网络成簇路由协议

分析了梯度和成簇无线传感器网络路由协议,确定了协议中存在的缺陷,设计了一种基于梯度的高效节能成簇路由协议(GBCRP)。采用基于跳数的梯度建立、能量相关的成簇算法、关键节点转发和功率自适应的簇头路由等技术,解决了无线传感器网络的节点能耗和路由失败而导致的数据传输可靠性问题。仿真实验表明,该协议有效地延长了网络的生命周期。针对不同密度的传感器节点,网络生命周期具有很好的稳定性,同时该协议也具有较好的可靠性保障。     

模糊车辆路径问题的一种混合遗传算法

在对模糊车辆路径问题进行简单描述的基础上,通过引入决策者主观偏好值的概念,给出了解决该问题的基本思路,建立了具有模糊特征的车辆路径问题的模糊机会规划模型,提出了求解该问题的一种基于模糊模拟的混合遗传算法。同时,在最小化总行驶距离的目标下,通过随机模拟方法研究了决策者主观偏好值的选择对最终决策目标的影响作用,并给出了其最佳取值范围。     

有顾客时间窗和发货量变化的车辆调度干扰管理研究

为解决由顾客需求变化引发的物流配送干扰问题,提出基于干扰管理思想构建扰动恢复策略和方案.应用虚拟多车场实现车辆调度扰动恢复问题转化.提出车辆调度扰动恢复策略和扰动度量方法,以作为车辆调度干扰管理建模的基础;分析顾客时间窗和发货量变化造成的扰动并进行辨识.建立相应的干扰管理模型,提出归一化处理办法对VRPTW、MD-VRPTW和MDVRPTW干扰管理问题进行有效兼容;结合干扰管理模型的特点,改进基于顾客的编码表示方法,可以反映出车辆调度扰动恢复策略;根据干扰管理思想,设计遗传算法对干扰管理模型进行求解.给出了一个具有代表性的算例试验结果,算例结果及其分析表明干扰管理模型和遗传算法的有效性.     

车辆路径问题的模型及算法研究综述

本文在文献[1,2,3,4]的基础上,首先,介绍了车辆路径问题的分类和限制条件;然后,全面综述了国内外关于车辆路径问题的模型及算法研究现状,重点探讨了车辆路径问题的模型构造、求解算法及其适用范围;最后,展望了其研究的前景。     

基于ASRank和MMAS的蚁群算法求解飞机指派问题

本文将航班串的飞机指派问题归结为车辆路径问题,考虑连续航班串之间衔接时间、衔接机场的约束、每架飞机的总飞行时间约束,建立了带有飞行时间约束的车辆路径问题的混合整数规划模型。构造了蚁群系统算法,引入基于排序的蚂蚁系统和最大最小蚂蚁系统算法的信息素更新策略。选取某航空公司7组初始航班串集合进行测试,并对算法中的重要参数进行了分析。实验结果表明,本文设计的模型和算法可以有效地减少连续航班串之间的总衔接时间,在可接受的计算时间内获得满意解。