物流配送车辆路径问题的优化研究

物流中的车辆路径问题(VRP)是目前组合优化领域的研究热点问题,VRP为NP-hard问题。本文在对VRP分析的基础上,建立数学模型,提出了一种适合求解该问题的蚁群遗传融合优化算法。提出的优化算法首先采用蚁群算法在局部阶段产生最好解,然后利用遗传算法的优良基因在全局阶段对优化解进一步优化,以获取最好路径解。实验结果表明,提出的融合算法能高效解决VRP问题,且优化效果比单算法好。     

车辆路径问题的双重进化蜂群算法求解研究

针对传统人工蜂群算法局部搜索的低效性,提出了双重进化人工蜂群算法。在需要两点进行操作的搜索过程中,采用一点随机选取,另一点通过遍历可行解,以其中最优解确定位置的半随机式搜索策略。用该策略改进插入点算子和逆转序列算子,分别在两对以及三对城市间距离之和的解空间维度上交叉搜索,并应用到局部搜索中构成双重进化过程,提高了搜索效率和适应值引导性。实验结果表明,该算法较已有方法提高了收敛速度,优化了目标解,并可通过合理设置终止阈值提高时效性。     

基于MATLAB的混合型蚁群算法求解车辆路径问题

蚁群算法是受自然界中蚁群搜索食物行为启发而提出的一种智能优化算法,通过介绍蚁群觅食过程中基于信息素的最短路径的搜索策略,给出了基于M ATLAB的蚁群算法在车辆路径问题中的应用,针对蚁群算法存在的过早收敛问题,加入2-opt方法对问题求解进行了局部优化,计算机仿真结果表明,这种混合型蚁群算法对求解车辆路径问题有较好的改进效果。     

混合算法在车辆路径优化问题中的应用

研究车辆路径优化问题,物流配送不仅要求配送及时,而且要求运输成本低,且路径最优。车辆路径优化是解决物流配送效率的关键,传统优化方法寻优效率低,耗时长,难以得到车辆路径最优解,导致物流配送成本过高。为了提高车辆路径寻优效率,降低物流配送成本,提出一种混合算法的车辆路径优化方法。首先建立车辆路径优化数学模型,然后用遗传算法快速找到问题可行解,再将可行解转换成蚁群算法的初始信息素,最后采用蚁群算法从可行解中找到最优车辆路径。仿真结果表明,混合方法提高车辆路径寻优效率,有效地降低物流配送成本。     

多策略优化的蚁群算法求解带时间窗车辆路径问题

提出一种新的蚁群算法求解带时间窗的车辆路径问题.在状态转移规则中,引入了时间启发函数,修改Ant Cycle模型信息素增量公式,引入等待或延误时间对信息素增量的影响.为避免算法陷入早熟,通过混沌扰动适当减小随机选取的最优路径上的信息素,按照客户坐标和时间窗改变已有解的组合方式对最优解进行调整.通过对相关文献实验数据的测试并与其他启发式算法所得结果进行比较,获得了较好的效果.     

基于DNA-蚁群算法的车辆路径优化问题求解

蚁群算法在解决车辆路径问题(VRP)时存在过早收敛于局部最优解、收敛速度慢等问题,并且由于蚁群算法的参数选择没有严格规定,如果参数选择不当,将影响其寻找最优解的效率。为解决上述问题,将DNA算法中的交叉变异思想应用于基本蚁群算法中,提出一种新的DNA-蚁群算法,将基本蚁群算法中的参数进行DNA交叉变异,有效控制蚁群算法的参数选择,从而得到一组最优参数来求解VRP模型。实验结果表明,DNA-蚁群算法能有效解决车辆路径优化问题,更快寻找到全局最优解或较优解,提高了基本蚁群算法的寻优能力和效率。     

求解车辆路径问题的一种混合方法

提出一种求解带软时间窗车辆路径问题的混合算法。采用蚁群系统算法产生阶段最优解,以此作为粒子模板,随机生成粒子群,利用粒子群算法在阶段最优解基础上进一步优化。且在蚁群系统算法中,当容量超过限制后,从剩余的客户里选择需求量最大的作为新的起点继续探索路径,直到所有客户都被访问一遍。实验表明,该混合算法是解决带软时间窗车辆路径问题的一个有效算法。     

蜂群优化算法在车辆路径问题中的应用

车辆路径问题（VRP）是组合优化中典型的NP难题。根据车辆路径问题的实际情况,考察车辆数和总行程两个目标函数,给出了该问题的一种新的算法,蜂群算法。通过计算若干benchmark问题,并将结果与其他算法相比较与分析,验证了算法的有效性。蜂群算法是刚刚起步的智能优化算法,目前国内外关于蜂群算法的文献较少,故不仅是拓宽蜂群算法的应用范围的有效的尝试,同时也给车辆路径问题提供了一种新的解决方法。     

求解车辆路径问题的改进遗传算法

车辆路径问题是一个典型的组合优化类问题,遗传算法是求解此类问题的方法之一。针对遗传算法容易出现“早熟”现象的问题,借鉴免疫算法通过抗体浓度抑制以保持种群多样性的优势以及模拟退火算法的个体选择策略,提出了一种改进的遗传算法,并将其用于解决车辆路径问题。实验验证了算法的有效性以及求解的效率和解的质量。     

基于改进型蚁群算法求解车辆路径优化问题的研究

针对蚁群算法在求解路径优化问题中存在收敛速度慢、易陷于局部最优路径等缺点进行了局部改进和优化,通过建立最近邻配送点矩阵来降低蚁群搜索空间,提高收敛速度。实验结果表明,改进型蚁群算法性能显著提高,能在较短时间内求得车辆路径问题较为满意的最优解。     

A survey of combinatorial optimization problems in multicast routing

In multicasting routing, the main objective is to send data from one or more sources to multiple destinations, while at the same time minimizing the usage of resources. Examples of resources which can be minimized include bandwidth, time and connection costs. In this paper, we survey applications of combinatorial optimization to multicast routing. We discuss the most important problems considered in this area, as well as their models. Algorithms for each of the main problems are also presented.     

求解绿色车辆路径问题的离散乌贼算法

为求解绿色车辆路径问题(green vehicle routing problem),提出一种离散乌贼算法(DCOA).采用轮盘赌机制增强初始解选择的随机性,引入精英片段插入策略指导乌贼细胞群的进化方向,提高搜索效率,利用2-opt法和shift法优化当前细胞,增强最优解的局部开发能力.选取Augerat标准数据集,对...     

A survey of multidisciplinary design optimization methods in launch vehicle design

Optimal design of launch vehicles is a complex problem which requires the use of specific techniques called Multidisciplinary Design Optimization (MDO) methods. MDO methodologies are applied in various domains and are an interesting strategy to solve such an optimization problem. This paper surveys the different MDO methods and their applications to launch vehicle design. The paper is focused on the analysis of the launch vehicle design problem and brings out the advantages and the drawbacks of the main MDO methods in this specific problem. Some characteristics such as the robustness, the calculation costs, the flexibility, the convergence speed or the implementation difficulty are considered in order to determine the methods which are the most appropriate in the launch vehicle design framework. From this analysis, several ways of improvement of the MDO methods are proposed to take into account the specificities of the launch vehicle design problem in order to improve the efficiency of the optimization process.     

A general heuristic for vehicle routing problems

We present a unified heuristic which is able to solve five different variants of the vehicle routing problem: the vehicle routing problem with time windows (VRPTW), the capacitated vehicle routing problem (CVRP), the multi-depot vehicle routing problem (MDVRP), the site-dependent vehicle routing problem (SDVRP) and the open vehicle routing problem (OVRP).     

A survey on two-echelon routing problems

The delivery of freight from its origin to its destination is often managed through one or more intermediate facilities where storing, merging and consolidation activities are performed. This type of distribution systems is commonly called multi-echelon, where each echelon refers to one level of the distribution network. Multi-echelon distribution systems are often considered by public administrations when implementing their transportation and traffic planning strategies as well as by private companies in their distribution networks. City logistics and multi-modal transportation systems are the most cited examples of multi-echelon distribution systems. Two-echelon distribution systems are a special case of multi-echelon systems where the distribution network comprises two levels. This latter type of distribution systems has inspired an ever growing body of literature in the last few years. This paper provides an overview of two-echelon distribution systems where routes are present at both levels. We consider three classes of problems: the two-echelon location routing problem, the two-echelon vehicle routing problem, and the truck and trailer routing problem. For each class we provide an introduction and survey the foremost related papers that have appeared in the operations research literature.     

An exact solution for vehicle routing problems with semi-hard resource constraints

This paper presents an exact solution procedure for a vehicle routing problem with semi-hard resource constraints where each resource requirement can be relaxed to a pre-fixed extent at a predefined cost. This model is particularly useful for a supply chain coordination when a given number of vehicles cannot feasibly serve all the customers without relaxing some constraints.It is different from VRP with soft time windows in that the violation is restricted to a certain upper bound, the penalty cost is flat, and the number of relaxations allowed has an upper bound.We develop an exact approach to solve the problem. We use the branch cut and price procedure to solve the problem modeling the pricing problem as an elementary shortest path problem with semi hard resource constraints. The modeling of the subproblem provides a tight lower bound to reduce the computation time. We solve this subproblem using a label setting algorithm, in which we form the labels in a compact way to facilitate incorporation of the resources requirement relaxation information into it, develop extension rules that generate labels with possible relaxations, and develop dominance criteria that reduce the computation time. The lower bound is improved by applying the subset-row inequalities.     

A planning model and solution algorithm for multi-trip split-delivery vehicle routing and scheduling problems with time windows

This study proposes a daily vehicle routing model for minimizing the total cost of replenishing inventory within a supply chain. The first major contribution of this research is to allow multiple use of vehicles in a split delivery vehicle routing problem with time windows (SDVRPTW), which is more realistic for various real-life applications. The multi-trip SDVRPTW (MTSDVRPTW) is formulated using the time–space network technique, which provides greater flexibility for formulating the complicated interactions between vehicles and products when multi-trip, split delivery, and delivery time windows are simultaneously considered. The resulting formulation of the MTSDVRPTW can be categorized as an integer multi-commodity network flow problem with side constraints. A two-step solution algorithm is proposed to solve this NP-hard problem, which is the second major contribution of this research. Finally, a real-world scale numerical example is performed to demonstrate and to test the methodology. The results indicate that these vehicle routing problems can be solved effectively and efficiently and that the proposed methodology has great potential for inventory replenishment scheduling where split deliveries and multiple trips for a single vehicle are allowed and time window constraints are imposed.     

带装载量约束的物流配送车辆路径优化研究

建立了物流配送车辆路径模型,设计了一种禁忌搜索算法,进行了多个算例测试和比较。测试表明模型的正确性,显示出禁忌搜索算法在物流配送车辆路径优化中计算时间节省、路程里程节省、总费用最小化等方面比遗传算法、模拟退火算法、蚁群算法及其混合算法具有明显的优势,能很好地适应现代物流对配送环节快速、低成本的要求。     

Particle swarm optimization and two solution representations for solving the capacitated vehicle routing problem

This paper presents two solution representations and the corresponding decoding methods for solving the capacitated vehicle routing problem (CVRP) using particle swarm optimization (PSO). The first solution representation (SR-1) is a (n + 2m)-dimensional particle for CVRP with n customers and m vehicles. The decoding method for this representation starts with the transformation of particle into a priority list of customer to enter route and a priority matrix of vehicle to serve each customer. The vehicle routes are then constructed based on the customer priority list and vehicle priority matrix. The second representation (SR-2) is a 3m-dimensional particle. The decoding method for this representation starts with the transformation of particle into the vehicle orientation points and the vehicle coverage radius. The vehicle routes are constructed based on these points and radius. The proposed representations are applied using GLNPSO, a PSO algorithm with multiple social learning structures, and tested using some benchmark problems. The computational result shows that representation SR-2 is better than representation SR-1 and also competitive with other methods for solving CVRP.