枢纽成本约束下的零担物流轴辐式网络设计

针对考虑枢纽建造成本和货物流的不确定的枢纽新建方案问题,引入全寿命周期理论,建立以轴辐式运营网络总成本最小化为目标的混合整数线性规划模型,并提出改进的最大最小后悔值的不确定性决策方法。通过算例来分析投资年限、枢纽干线折扣系数和不确定枢纽建造成本对零担物流（LTL）轴辐式网络的设计的影响。实验结果表明, 采用改进的不确定性决策方法得到的最优方案的运营成本比5个场景的运营成本平均降低了2.17%,表明基于改进的最大最小后悔值的不确定性决策方法,能够降低整个零担物流轴辐式运营网络总成本。     

考虑区间约束的物流网络双层规划模型及算法

考虑物流网络需求的不确定性,利用区间参数度量不确定性变量与参数,建立区间需求模式下的物流网络双层规划模型,设计了一种含区间参数与变量的递阶优化遗传算法,通过定义问题求解的风险系数与最大决策偏差,给出适合物流网络结构的区间运算准则,实现模型的确定性转化。以区间松弛变量与0-1决策变量定义初始种群,通过两阶遗传操作运算,求解不同情景下双层规划目标的区间最优解与节点决策方案。算例测试表明算法求解的可操作性更强,求解结果具有区间最优解与情景决策的优越性。     

面向空铁联运的枢纽航线网络优化模型

为减缓枢纽机场的客流量拥堵问题,减少机场运营成本,设计面向空铁联运的枢纽航线网络优化模型.在枢纽航线网络基础上,引入高铁线路建立优化模型;设计高维多角标变量表示方法和禁忌搜索算法的求解方法,减少算法的计算负担,科学规划线路客流量和运输方式.实验结果表明,与严格和非严格的枢纽航线网络相比,该优化模型可以较好减缓枢纽机场的拥堵,降低枢纽机场的负荷率,减少网络成本.该模型求解算法具有收敛速度快且解分布稳定的特点.     

混合轴辐式零担网络多目标车辆调度研究

单一指派多枢纽混合轴辐式网络是零担快运的主要形式。此类网络的车辆调用是快运企业保障运营质量及维持合理的运营成本的关键问题之一。综合考虑自有储备运力、外请临时运力的安全性、便利性和经济性,并将以上多目标优化转化为单目标优化问题,构建车辆调度数学模型,设计模型求解的遗传算法。通过算例验证得出合理的车辆调度方案,实现了运力资源的合理配置。     

区间不确定性需求下的D-LFLP模型及算法

考虑物流网络需求的不确定性,运用区间分析理念以区间数度量不确定性变量与参数,建立区间需求模式下的物流网络设计的混合整数规划模型,定义风险系数与最大约束偏差,对模型进行目标函数与约束条件的确定性转化,设计问题求解的区间递阶优化遗传算法,对不同情景状态下目标函数的区间最优解与节点决策方案进行运算。算例测试表明该算法可操作性更强,求解结果具有区间最优解与情景决策的优越性。     

基于轴辐模式的物流网络构建及实证研究

本文研究轴辐式物流网络构建的思路和方法，从社会经济发展水平、产业结构布局、物流发展水平等方面的选取GDP、工业总产值、固定资产投资第三产业占比、公路货运量等七项指标，构建物流网络评价指标体系，并以德州市十二个县区的相关数据为研究对象，运用主成分分析法计算德州市各个县、区的物流综合能力，并确定天衢新区、齐河、乐陵三个物流枢纽节点，通过引力模型确定三个物流枢纽节点的辐射范围，得到德州市轴辐式物流网络，为德州市物流业的进一步发展提供借鉴。     

考虑客户吸引力的轴辐式海运网络优化

针对轴辐式集装箱海运网络优化问题,引入了基于服务约束(服务质量\价格\时间)的客户吸引力因素,定量表示出客户吸引力对集装箱货运量的影响。以海运网络中航运企业的利润最大化为目标,建立了轴辐式海运网络优化模型。使用遗传算法求解,通过算例分析证明该模型及算法的有效性,并分析了不同的规模经济折扣率、托运人的决策偏好权重对航运企业利润的影响。     

多分配枢纽站集覆盖问题的随机p- 鲁棒优化模型及算法

枢纽站选址是轴辐式网络优化设计的重要问题,枢纽站覆盖则是该问题的一个类型.考虑枢纽站建站成本和节点间运输距离的不确定性,结合随机优化和鲁棒优化方法,建立了完备轴辐式网络中多分配枢纽站集覆盖问题的随机-鲁棒优化模型;采用二进制编码,对量子粒子群算法进行改进,加入免疫思想,设计了免疫量子粒子群求解算法.最后通过算例对模型进行仿真计算,结果表明了该模型及算法的可行性和有效性.     

铁路快捷货运班列轴幅式服务网络设计优化

为了使铁路快捷货物运输更加适应物流化的需求,研究轴幅式网络下铁路物流基地站间快捷货运班列服务网络设计问题.以固定成本、变动成本和惩罚成本最小为目标,构建单目标混合整数线性规划模型,同时囊括客户送达时间和班列服务等级要求,以及铁路线路通过能力限制,并结合模型特点和问题规模,设计遗传算法求解模型.最后,通过切实案例验证了模型和算法的有效性.算例结果表明,所提出的模型和算法可有效地描述和求解实际问题,同时,基于轴幅式网络的服务网络设计思路和方法对铁路快捷货物运输组织有一定的借鉴意义.     

两阶段式的物流配送路径优化方法

根据组合优化理论,充分利用遗传算法、蚁群算法的优化点,提出了一种两阶段式的物流配送路径优化方法(GA-ACO)。利用遗传算法迅速找到物流配送路径优化问题的初始解,初始解生成蚁群算法的初始信息素分布,通过蚁群算法找到物流配送路径的最优方案。采用实例对GA-ACO的性能进行测试,测试结果表明,GA-ACO可以获得较好的物流配送路径优化方案,是一种高效率、鲁棒性好的物流配送路径优化问题求解方法。     

非严格的中枢辐射航线网络设计的鲁棒优化方法

为解决中枢辐射航线网络设计结果易受参数不确定性影响的问题,首先在需求和成本具有不确定性的条件下,建立了非严格意义上的无容量限制的中枢辐射航线网络鲁棒优化模型,并采用鲁棒优化方法对航线网络进行优化设计.然后结合中枢辐射航线网络实际应用中枢纽个数少的特点,对最短路算法加以改进,提出了一种求解航线网络鲁棒优化设计的精确算法,得到了适用于多种可能情景的鲁棒解.最后利用有关的成本和需求数据对该方法进行了验证;结果表明,鲁棒优化设计方法对航空公司构建中枢辐射航线网络具有很好的实用性.     

Capacitated single-allocation hub location model for a flood relief distribution network

In disaster management, the logistics for disaster relief must deal with uncontrolled variables, including transportation difficulties, limited resources, and demand variations. In this work, an optimization model based on the capacitated single-allocation hub location problem is proposed to determine an optimal location of flood relief facilities with the advantage of economies of scale to transport commodities during a disaster. The objective is to minimize the total transportation cost, which depends on the flood severity. The travel time is bounded to ensure that survival packages will be delivered to victims in a reasonable time. Owing to complexity of the problem, a hybrid algorithm is developed based on a variable neighborhood search and tabu search (VNS-TS). The computational results show that the VNS found the optimal solutions within a 2% gap, while the proposed VNS-TS found the optimal solution with a 0% gap. A case study of severe flooding in Thailand is presented with consideration of related parameters such as water level, hub capacity, and discount factors. Sensitivity analyses on the number of flows, discount factors, capacity, and bound length are provided. The results indicated that demand variation has an impact on the transportation cost, number of hubs, and route patterns.     

A genetic algorithm for the uncapacitated single allocation planar hub location problem

Given a set of n interacting points in a network, the hub location problem determines location of the hubs (transfer points) and assigns spokes (origin and destination points) to hubs so as to minimize the total transportation cost. In this study, we deal with the uncapacitated single allocation planar hub location problem (PHLP). In this problem, all flow between pairs of spokes goes through hubs, capacities of hubs are infinite, they can be located anywhere on the plane and are fully connected, and each spoke must be assigned to only one hub. We propose a mathematical formulation and a genetic algorithm (PHLGA) to solve PHLP in reasonable time. We test PHLGA on simulated and real life data sets. We compare our results with optimal solution and analyze results for special cases of PHLP for which the solution behavior can be predicted. Moreover, PHLGA results for the AP and CAB data set are compared with other heuristics.     

考虑港口拥堵因素的沿海海运网络优化

沿海运输权制度是沿海运输是否保留给本国船舶或者向外国籍船舶开放的制度。港口拥堵主要发生在海运网络的枢纽港上。通过考虑沿海运输权和港口拥堵对轴辐式海运网络加以优化,以海运网络内货物运输总成本最小化为目标函数,构建一个小规模整数规划模型。从欧亚航线覆盖的主要地区中选取10个港口组成海运网络进行算例分析,并使用CPLEX软件进行求解,研究结果表明,通过考虑枢纽港间货物运输的规模经济效应和产生的拥堵成本,可合理地确定枢纽港的位置;若允许沿海捎带,外资航运企业将会改变货物中转的港口。     

基于换乘导向的大型客运枢纽高铁列车接续优化

针对高速铁路成网条件下的客运枢纽高铁列车接续优化问题,分析了枢纽内的旅客换乘过程,提出了中长途客流的换乘满意度概念;以平均换乘满意度和枢纽车站列车到发均衡性为优化目标,以大站合理发车时间、合理终到时间、车站作业间隔时间、旅客换乘时间、车站到发线能力等为约束条件,建立了基于换乘协同的大型客运枢纽高速列车接续优化模型。设计了改进染色体编码方式和选择策略的遗传算法对算例进行了求解。改进后的遗传算法同基本遗传算法、基本模拟退火算法相比,目标函数中所求的平均换乘满意度分别增加了5.10%、2.93%,枢纽车站列车到发均衡性分别提高了0.27%、2.31%,算例结果验证了改进遗传算法的有效性和稳定性,表明所提方法可以有效地提高大型枢纽高铁列车的接续质量。     

A model for a reliable single allocation hub network design under massive disruption

Hub facilities may fail to operate in networks because of accidental failures such as natural disasters. In this paper, a quadratic model was presented for a reliable single allocation hub network under massive random failure of hub facilities which more than one hub may be disrupted in a route. It determines the location of the hub facilities and the primal allocation of non-hub nodes. It also determines the backup allocation in case of failure of the primal hub. First, a new lexicographic form of a bi-objective quadratic model is presented where the first objective maximizes served demands or equivalently, minimizes lost flows and the second objective minimizes total cost under a to massive disruption in the network. Then, by adding a structure-based constraint, the model is transformed to a single objective one. A linearization technique reported in the literature is applied on the quadratic model to convert it into classic linear zero–one mixed integer model while enhancing it by finding tighter bounds. The tight bounds’ technique is compared with other techniques in terms of computational time and its better performance was approved in some problem instances. Finally, due to the NP-hardness of the problem, an iterated local search algorithm was developed to solve large sized instances in a reasonable computational time and the computational results confirm the efficiency of the proposed heuristic, ILS can solve all CAB and IAD data set instances in less than 15 and 24 seconds, respectively. Moreover, the proposed model was compared with the classical hub network using a network performance measure, and the results show the increased efficiency of the model.     

区域低碳物流运输网络双层优化研究

区域低碳物流网络优化是建立低碳物流系统的重要环节。引入低碳理念,考虑政府低碳线路规划与货主之间的博弈,上层区域物流网络的优化以碳排放、成本、时间最少化,下层货流运用改进的Logit路径选择分配,建立了基于低碳理念的区域物流运输网络双层优化模型。根据模型求解的复杂性,运用网络变形和遗传算法给出求解优化模型的方法和步骤。算例仿真计算结果表明,该模型与算法在区域物流运输网络低碳优化组合中是准确且可行的,有益于低碳物流网络构建。     

Cooperation and profit allocation in two-echelon logistics joint distribution network optimization

Collaborative two-echelon logistics joint distribution network can be organized through a negotiation process via logistics service providers or participants existing in the logistics system, which can effectively reduce the crisscross transportation phenomenon and improve the efficiency of the urban freight transportation system. This study establishes a linear optimization model to minimize the total cost of two-echelon logistics joint distribution network. An improved ant colony optimization algorithm integrated with genetic algorithm is presented to serve customer clustering units and resolve the model formulation by assigning logistics facilities. A two-dimensional colony encoding method is adopted to generate the initial ant colonies. Improved ant colony optimization combines the merits of ant colony optimization algorithm and genetic algorithm with both global and local search capabilities. Finally, an improved Shapley value model based on cooperative game theory and a cooperative mechanism strategy are presented to obtain the optimal profit allocation scheme and sequential coalitions respectively in two-echelon logistics joint distribution network. An empirical study in Guiyang City, China, reveals that the improved ant colony optimization algorithm is superior to the other three methods in terms of the total cost. The improved Shapley value model and monotonic path selection strategy are applied to calculate the best sequential coalition selection strategy. The proposed cooperation and profit allocation approaches provide an effective paradigm for logistics companies to share benefit, achieve win–win situations through the horizontal cooperation, and improve the negotiation power for logistics network optimization.