海运服务链中的运力定价和空箱调运责任研究

本文研究了单个承运商和两个货运代理在双向港口间提供往返货运服务的航运服务链。由于港口间货运需求的内在不平衡,货运公司在多港口间的空箱调运会产生巨大的空箱调运费用。分别构建了承运商承担和承运商与货运代理共同承担空箱调运的数学模型,通过数学模型和数值算例分析了不同市场条件下的空箱调运责任和运力定价策略。研究发现承运商和货运代理是否采用定价策略来平衡需求取决于双向港口间货运市场的潜在需求差异。同时,承运商与货运代理的空箱调运分摊为非此即彼策略,当空箱调运成本大于某阈值时,承运商独自承担空箱调运责任;反之,货运代理承担空箱调运责任。而且货运代理承担模式增加整个海运链的利润,但进一步加剧空箱的不平衡状况。     

存在空箱调运的非对称运输市场定价策略研究

考虑空箱调运成本,本文对垄断和双寡头市场分别研究运输企业在两条相向路径上的定价问题。对于垄断市场,建立了运输企业最优定价策略,并刻画出无空箱调运的潜在需求不平衡区间。对于双寡头市场,考虑同一路径上不同企业潜在运输需求不等的现实情境,求解了非对称企业的伯川德纳什均衡,给出最优定价策略。研究发现,无空箱调运并不意味着较高利润,运输企业没有必要刻意消除空箱调运现象。另外,增加单位载货运输成本和竞争强度会降低企业利润,而提升单位空箱重置成本、价格敏感度和市场不对称程度都会增大企业利润。     

基于供需网企业合作博弈模型的演化路径分析

传统企业间合作博弈问题的研究大都是基于合作策略和不合作策略两种情形展开,而与传统研究不同,本文在此基础上将企业间不合作策略细分为竞争策略和中立策略。以多功能开放型供需网企业为研究对象,运用演化博弈理论分析方法,通过构建供需网企业合作演化博弈模型,进而分析供需网企业合作过程中策略的选择以及博弈演化路径问题。研究结果表明:在长期的演化博弈过程中,企业策略的选择情形出现不稳定现象,即出现完全合作、完全不合作或者一方合作而另一方选择不合作策略的多种状态,其演化路径最终稳定于何种情形与模型的支付矩阵和初始参数设置有关。     

供应商歧视定价下网络零售商店内推介策略研究

研究了供应商歧视定价时网络零售商店内推介策略。首先,以供应商统一定价模型为基准,通过逆推归纳法求解不同推介策略组合下零售商和供应商的均衡利润,研究发现:仅当消费者对两家零售商认知差异较小时四种推介策略组合才能同时成立,且随着推介费用的增大两零售商均衡推介策略依次为:都不推介、仅强势零售商1推介和双向推介。其次,构建供应商歧视定价模型,发现歧视定价有利于弱势零售商2获得市场空间,随着消费者对两家零售商感知差异和推介费用的变化呈现出多样化的均衡推介策略。最后,探讨了两种定价模型下供应商的最优利润,发现受推介策略的影响歧视定价未必能够为供应商带来更多利润。     

提前期不确定条件下的预防性维修备件存储模型研究

在考虑预防性维修周期和提前期不确定的条件下,分别研究备件存储与其相关的维修费用、缺货费用、库存费用以及订购费用等四种费用之间的关系,明确了备件存储量对各项费用的影响.以各项费用总和最小化为目标,构建了提前期不确定条件下的预防性维修备件存储模型.通过备件存储模型的构建,对备件存储过程中的各项成本进行分析,以期对备件库存策略的确定给出一种解决方案.     

产出不确定下易逝品限量预售鲁棒策略分析

限量预售是融合供需对接而成的复合型销售模式,正受到企业上市易逝品的青睐.在产出不确定环境下,基于易逝品随机产出因子部分信息,构建生产商在正常销售前引入限量预售的两阶段鲁棒报童模型,在鲁棒决策下探讨了预售策略.研究表明:限量预售既能纾解产出不确定风险导致的供需矛盾,又能减小该风险对期望利润带来的冲击;限量预售模式选择的阈值条件由易逝品随机产出因子变异系数,两阶段销售价格及需求影响因子共同权衡确定.同时,发现鲁棒最优预售量及其影响因素并提供了策略建议.     

多类型公共自行车调运问题

公共自行车是我国正大力发展的低碳交通出行模式,加强公共自行车调运优化是提升自行车出行吸引力的关键要素。通过对公共自行车调运背景分析,提出了一类多类型公共自行车的调运优化问题。针对现实生活中租赁站点内公共自行车不均衡的情况,建立了以总成本最小为目标的混合整数线性规划模型,并提出一种改进的混合禁忌搜索对问题进行求解。通过数值实验分析了问题特性并验证了算法性能。实验结果表明非均衡惩罚系数决定了租赁站点各类自行车的装卸载数量,并影响了调配车辆的运行路线,是实现多类型公共自行车均衡优化的关键因素。不同类型自行车的替代策略使得调运决策更加灵活。混合禁忌搜索可以求解更大规模的问题,并能在短时间内求得较好质量的解。     

防洪物资调运的数学模型

首先构建防洪物资调运的交通网络矩阵模型,并利用Dijkstra算法寻找各调运节点之间的最优路线,然后在平时以追求最小总调运费用、紧急情况下以追求最快调运速度为目标建立了防洪物资调运的优化模型,在此过程中引入偏离控制量以便充分考虑各调运节点的需求,讨论了调运期、偏离控制量对调运费用的影响,为科学制定调运方案提供依据,较好地解决了防洪物资的调运问题.     

考虑共因失效和负载分担的表决系统维修优化分析

随着仪器设备的大型化、精密型和复杂化，传统的单一故障模型很难精确地描述系统。针对可修的表决系统，考虑了负载分担和共因失效两种失效模式，提出了不完美的故障检测策略，并对模型进行了可靠性和维修性分析，求得了系统的瞬时可用度、稳态可用度和平均维修费用。最后通过数值案例给出了同时考虑可用度和维修费用的最优检测策略，能够为设备管理者提供决策依据。     

供需双重不确定下SaaS服务供应链协调分析

针对"软件即服务(Software-as-a-service,SaaS)"模式,从服务供应链的视角研究了在线应用(软件)服务市场需求和网络服务提供商供给双重不确定下,网络服务提供商与应用服务提供商之间的协调问题。首先分析了由网络服务提供商与应用服务提供商组成的SaaS服务供应链分别在集中式和分散式下的最优决策,然后提出了特许经营费用契约来实现成本分摊、风险共担从而使SaaS服务供应链实现协调。此外,数值分析部分一方面验证了该契约的有效性,另一方面展示了供需不确定对供应链利润的影响。研究结果表明:该契约能有效协调SaaS服务供应链,并同时提高网络服务提供商与应用服务提供商的收益,即实现帕累托改进。该契约同时考虑SaaS服务供应链供需不确定问题,具有较强应对风险的能力。     

Allocation of empty containers between multi-ports

Owing to imbalances in international trade activities, shipping companies accumulate a large number of unnecessary empty containers in the import-dominant ports, whilst request a large number of empty containers in export-dominant ports. The logistics challenge to shipping companies is to better manage and control their containers, which consist of company-owned containers and leased containers. The multi-port empty container allocation problem is concerned with the allocation of empty containers from supply ports to demand ports. In this paper, optimal pairs of critical policies, (U, D) for one port, which are importing empty containers up to U when the number of empty containers in the port is less than U, or exporting empty containers down to D when the number of empty containers is larger than D, doing nothing otherwise, are adapted to multi-port case so that decision-makers can make decisions about allocating the right amounts of empty containers to the right ports at the right time. This allocation problem has been formulated and the heuristic methods are designed according to that the average cost using (u, d) policy at one port is convex in u and d. Furthermore, the examples show that, using the heuristic algorithm, the result in the inland line case is quite close to the lower bound, even the distance is not so close in the global line case.     

Robust empty container repositioning considering foldable containers

Because of the extreme imbalance in intercontinental trade, the repositioning of empty containers creates a significant problem for shipping companies. There are many efforts to reduce the cost of repositioning empty containers, one of which is a foldable container. This paper proposes a robust formulation for the empty container repositioning problem considering foldable containers under demand uncertainty. The robust formulation can be used as a tractable approximation of a multistage stochastic programming formulation which is computationally intractable. Moreover, the robust formulation requires only limited information about the distribution of demand to replicate real-world situations. Computational results show that the proposed formulation performs well in terms of operating costs and there exists a significant cost-saving effect when foldable containers are used in maritime transportation.     

基于遗传算法与贪婪策略的多港口集装箱配载研究

在物流运输行业中,集装箱运输已经成为我国长江沿岸各大港口的主要运输业务。集装箱的处理流程,尤其是集装箱的配载过程直接影响着班轮的运输效率,配载方案的制定对班轮运输起着至关重要的作用。本文针对多港口集装箱船的配载情况,利用CPLEX对该线性规划问题进行求解,并设计遗传算法和贪婪算法对长江沿岸多港口集装箱船配载情形进行对比。通过仿真实验,在小规模时遗传算法与CPLEX求解的精确解相同,验证了遗传算法的有效性。并且在大规模运输情形下,遗传算法得出的结果明显优于贪婪策略,进一步说明了遗传算法是行之有效的。得出的解决方案降低了班轮公司的运输成本,提高了港口的工作效率,对我国长江沿岸港口集装箱配载计划的制定具有一定的指导作用。     

A mathematical model of inter-terminal transportation

We present a novel integer programming model for analyzing inter-terminal transportation (ITT) in new and expanding sea ports. ITT is the movement of containers between terminals (sea, rail or otherwise) within a port. ITT represents a significant source of delay for containers being transshipped, which costs ports money and affects a port’s reputation. Our model assists ports in analyzing the impact of new infrastructure, the placement of terminals, and ITT vehicle investments. We provide analysis of ITT at two ports, the port of Hamburg, Germany and the Maasvlakte 1 & 2 area of the port of Rotterdam, The Netherlands, in which we solve a vehicle flow combined with a multi-commodity container flow on a congestion based time–space graph to optimality. We introduce a two-step solution procedure that computes a relaxation of the overall ITT problem in order to find solutions faster. Our graph contains special structures to model the long term loading and unloading of vehicles, and our model is general enough to model a number of important real-world aspects of ITT, such as traffic congestion, penalized late container delivery, multiple ITT transportation modes, and port infrastructure modifications. We show that our model can scale to real-world sizes and provide ports with important information for their long term decision making.     

灾后运输网络中的最短路修复合作博弈

在最短路修复合作博弈中,当灾后运输网络规模较大时,最优成本分摊问题难以直接求解。基于拉格朗日松弛理论,提出了一种最短路修复合作博弈成本分摊算法。该算法将最短路修复合作博弈分解为两个具有特殊结构的子博弈,进而利用两个子博弈的结构特性,可以{高效地}求解出二者的最优成本分摊,将这两个成本分摊相加,可以获得原博弈的一个近乎最优的稳定成本分摊。结果部分既包含运输网络的随机仿真,也包含玉树地震灾区的现实模拟,无论数据来源于仿真还是现实,该算法都能在短时间内为最短路修复合作博弈提供稳定的成本分摊方案。     

Shipping Container Logistics and Allocation

A major shipping company in Hong Kong is faced with several logistical and allocation problems. It needs to find a better way to allocate empty containers that are transported from the Middle East to ports in the Far East, subject to vessel schedules and capacities. It needs to know what to do when the supply of empty containers is less than the demand, and it needs to determine the mix of container types that the company should maintain in the long run. To deal with these challenges, a simulation model of the shipping company's operational activities was developed. Heuristic search was employed to identify the policies that yield the lowest operating cost in terms of leasing, storage, pick-up, drop-off and other charges. What makes the problem difficult is that the forecasts of future export movement as well as the demand for empty containers change continually and the company is faced with the possibility of lost sales if containers are not available when requested by customers. This study provided insights that resulted in substantial savings to the shipping company while increasing customers' satisfaction.     

Capacitated transportation problem with bounds on RIM conditions

Motivated by dead-mileage problem assessed in terms of running empty buses from various depots to starting points, we consider a class of the capacitated transportation problems with bounds on total availabilities at sources and total destination requirements. It is often difficult to solve such problems and the present paper establishes their equivalence with a balanced capacitated transportation problem which can be easily solved by existing methods. Sometimes, total flow in transportation problem is also specified by some external decision maker because of budget/political consideration and optimal solution of such problem is of practical interest to the decision maker and has motivated us to discuss such problem. Various situations arising in unbalanced capacitated transportation problems have been discussed in the present paper as a particular case of original problem. In addition, we have discussed paradoxical situation in a balanced capacitated transportation problem and have obtained the paradoxical solution by solving one of the unbalanced problems. Numerical illustrations are included in support of theory.     

考虑空重箱转换的港口集装箱甩挂运输问题研究

针对港口堆场与内陆腹地客户之间的空重集装箱运输问题,本文结合甩挂运输的特点将客户的进出港需求拆分为相互关联的空箱和重箱任务,实现单个决策期内运输系统中集装箱的状态转换与回收工作。状态转换受集装箱货物装卸时间影响,因此需要合理调度牵引车路线,以满足前置任务约束。针对此类问题的特点,本文建立了空重箱运输任务整合的整数规划模型,并设计了基于集群选择的改进蚁群算法进行求解。最后,通过不同规模的仿真算例与现有数学模型及优化算法对比结果可知,本文所提出的改进蚁群算法在此类问题的最优解搜索中具有良好的稳定性和求解效率。