A genetic algorithm for the hub-and-spoke problem applied to containerized cargo transport

A genetic algorithm for the hub-and-spoke problem (GAHP) is proposed in this work. The GAHP configures a hub-and-spoke network with shuttle services for containerized cargo transport. For a fixed number of hubs, it determines the best network configuration of hub locations and spoke allocations that minimizes the total costs of the system. The GAHP has a simple individual structure with integer number representation, where spokes, their allocations, and hub locations are easily recognized. Due to the characteristics of the problem, which has fixed number of hubs, rearrangements should be performed after every process. The GAHP rearrangement process includes improvements of individual structures, resulting in an improved population. Before applying the GAHP to the container transport network problem, the algorithm is validated using the Civil Aeronautics Board data set, which is extensively used in the literature to benchmark heuristics of hub location problems. To illustrate an example of a hub-and-spoke network with shuttle services, a study case with 18 ports is analyzed.     

Fleet deployment in liner shipping: a case study

The fleet deployment problem is an important planning problem in liner shipping. It deals with optimally assigning voyages to available vessels in the fleet and determining vessel routes and schedules in a way that minimizes costs or maximizes profit. This paper presents a new model for a fleet deployment problem in liner shipping, and we also propose a multi-start local search heuristic to solve the problem. The heuristic has been embedded in a prototype decision support system (DSS) that has been implemented and tested at Höegh Autoliners, a major global provider of ro-ro (roll-on roll-off) vehicle transportation services. The heuristic was able to produce high-quality solutions within a few minutes to a real planning problem with more than 55 vessels and 150 voyages over a planning horizon of 4–6 months. Tests indicated that the solutions suggested by the DSS gave between 2 and 10% improvements compared with solutions from manual planning. What is almost equally important is that using the DSS can ease the planning process.     

On cost-efficiency of the global container shipping network

This paper presents a simple formulation in the form of a pipe network for modelling the global container-shipping network. The cost-efficiency and movement-patterns of the current container-shipping network have been investigated using heuristic methods. The model is able to reproduce the overall incomes, costs, and container movement patterns for the industry as well as for the individual shipping lines and ports. It was found that the cost of repositioning empties is 27% of the total world fleet running cost and that overcapacity continues to be a problem. The model is computationally efficient. Implemented in the Java language, it takes one minute to run a full-scale network on a Pentium IV computer.     

An analysis of decision-making processes in multicultural maritime scenarios

This paper presents a simple formulation in the form of a pipe network for modelling the global container-shipping network. The cost-efficiency and movement-patterns of the current container-shipping network have been investigated using heuristic methods. The model is able to reproduce the overall incomes, costs, and container movement patterns for the industry as well as for the individual shipping lines and ports. It was found that the cost of repositioning empties is 27% of the total world fleet running cost and that overcapacity continues to be a problem. The model is computationally efficient. Implemented in the Java language, it takes one minute to run a full-scale network on a Pentium IV computer.     

Fleet deployment optimization for liner shipping Part 2. Implementation and results

We use linear programming (LP) for solving the problem of the optimal deployment of an existing fleet of multipurpose or fully containerized ships, among a given set of routes, including information for lay-up time, if any, and type and number of extra ships to charter, based on a detailed and realistic model for the calculation of the operating costs of all the ship types in every route and on a suitable LP formulation developed in earlier work of the authors. The optimization model is also applicable to the problem of finding the best fleet compostion and deployment, in a given set of trade routes, which may be the case when a shipping company is considering new or modified services, or a renewal of the existing fleet. In addition, two promising mixed linear-integer programming formulations are suggested.     

我国进口铁矿石海运网络分析

本文在预测了本世纪本我国铁矿石进口的基础上构筑了其海运网络。运用网络流模糊规划方法按最大最小费用流问题对矿石货流进行了合理安排。     

基于混沌优化的港口集装箱运输网络优化

随着集装箱船舶大型化的发展,航运公司势必会尽可能的选择科学、合理的航线,以实现大型集装箱船的规模效益,降低单箱运输成本,从而获得更大的效益。这样集装箱港口出现了枢纽港与支线港的分离。本文以体现大型集装箱船的规模效益为前提,尝试将混沌优化这一理论应用到港口运输网络的优化中,寻找合理的港口集装箱运输线路及服务频率,为我国港口集装箱运输提供决策依据。     

Spatial pattern of the global shipping network and its hub-and-spoke system

Port system is a research focus of transport geography, and most studies believe carriers are important factors in the development and concentration of the port system. Since the 1990s, carriers have played an important role in organizing the global shipping network and reorganizing the port system. But there isn’t a perfect method to evaluate carriers’ influence and the roles of each port in the maritime shipping networks. In this paper, we use the monthly schedule table of international carriers to describe and model the spatial pattern of the global shipping network and identify its hub-and-spoke system. The result shows that a hierarchical structure exists in the global shipping network. The North Hemisphere, especially the East Asia and the Southeast Asia, is a dominant region of the worldwide shipping network. East Asia, Southeast Asia, Northeast Europe, and East coast of the USA are the concentration regions of worldwide shipping lines. The ports of Hong Kong, Singapore, Shenzhen, Shanghai, and Kaohsiung etc have advanced capacity for maritime shipping and high potentials for being hub ports in the global shipping network. Today, the worldwide shipping network is transforming from the multi-port calling system to 44 regional hub-and-spoke systems. Meanwhile, the sub-networks with hub ports of Antwerp, Singapore, and Hong Kong have become the most important ones and dominate the whole global shipping network.     

A reactive container rerouting model for container flow recovery in a hub-and-spoke liner shipping network

This paper focuses on the container rerouting due to a disruption, aims at making the optimal container flow recovery plan for the affected liner shipping company. First, we make the initial effort to bring up with a basic framework of disruption management for liner shipping. Second, we present a compact integer linear programming model for addressing the container rerouting problem under the proposed framework in a hub-and-spoke liner shipping network, based on a given recovery vessel schedule that determines to omit a port of call. Other shipping companies’ services and other modes (roadway, railway, and airline) as candidate alternative means to transport the miss-connected containers are also incorporated in the proposed model. The container flow recovery plan would select the optimal alternative paths for the miss-connected containers balancing the trade-off between container transport costs and delivery delay penalty costs. Finally, a case study from a global liner shipping company is investigated and the computational results indicate the model can be solved effectively and efficiently for the real-scale problem. Thus, the proposed approach in this paper can supply real-time decision support tool for the liner shipping operators on handling the process of container flow recovery.     

Evaluation of factors for carrier selection in the China Pearl River delta

The efficient integration of logistics modes is critical for international cargo shipping. The local transportation connecting to the export port then plays a vital role in such integration. This paper investigates the problems of carrier selection in the China Pearl River delta area, with respect to international shipping. The analytical hierarchy process (AHP) model is constructed based on a comprehensive industrial interviews and statistical analysis. Rather than simply ranking the given alternatives, we use AHP is used to analyse the weakness and strength of impacting factors in carrier selection. The model is implemented under different types of shipper. Seven criteria are statistically summarized from the questionnaire for evaluating eight different modes. The results are useful to those liner companies serving the PRD region in relationship to port selection and fleet deployment.     

Evaluation of factors for carrier selection in the China Pearl River delta

The efficient integration of logistics modes is critical for international cargo shipping. The local transportation connecting to the export port then plays a vital role in such integration. This paper investigates the problems of carrier selection in the China Pearl River delta area, with respect to international shipping. The analytical hierarchy process (AHP) model is constructed based on a comprehensive industrial interviews and statistical analysis. Rather than simply ranking the given alternatives, we use AHP is used to analyse the weakness and strength of impacting factors in carrier selection. The model is implemented under different types of shipper. Seven criteria are statistically summarized from the questionnaire for evaluating eight different modes. The results are useful to those liner companies serving the PRD region in relationship to port selection and fleet deployment.     

编队作战需求下舰船修理周期结构的优化

舰船全寿命期内的部署和修理活动需要在其修理周期结构的指导下进行,而编队的使用则需要编队内各舰艇的修理周期结构的相互配合,从而使编队拥有更高的部署能力。文章建立了编队修理周期结构的优化模型,考虑了同一舰级下舰艇相互代替使用的情况,更能真实反映编队的部署和修理情况,采用遗传算法对编队的部署能力进行优化分析,实例证明优化后可以显著提高编队的部署能力,为进一步研究编队的部署维修奠定了基础,同时在单舰的修理周期结构上加上了编队使用需求这一约束条件,拓展了研究舰船修理周期结构的思路。     

基于改进蚁群算法的物流网络

文中将受容量限制的单分配轴-辐式网络抽象为一个三次变量的混合整数线性规划模型方程;提出了一种改进的蚁群算法,将6种局域搜索算子加入算法中,因此具有较高的全局搜索能力和局部搜索能力;同时提出“解对”的概念,对问题的构成进行分解优化,转化为确定问题,切实使本问题符合蚁群算法使用的前提和优势;最后,使用澳大利亚邮政的数据进行选址仿真实验,验证此算法模型在该应用中的求解效率和计算稳定性。     

连续泊位调度与岸桥配置协同优化

连续泊位调度与岸桥配置协同优化是集装箱码头提升竞争力的关键因素.针对该问题构建一个混合整数规划模型,以构造算法为核心,通过调整船舶的分配次序,设计了一个新的启发式算法.通过VB6.0软件编程,进行了四组大规模仿真算例实验,结果显示60%的算例在新算法下可获得更优的解,平均改进7.37%,证明了模型和算法的有效性.     

舰艇编队网络互联机制研究

论文通过对舰艇编队网络模型进行分析,提出了一种适用于舰艇编队网络的无线异构网络互连协议WHRP,实验结果表明WHRP协议在路由协议开销较小的情况下能够提供较好的网络性能,同OLSR、AODV相比,更加适合舰艇编队战术无线通信网络环境.     

Port system evolution – the emergence of second-tier hubs

Some evidence has emerged of second-tier hubs inserting themselves between hubs and feeder ports, producing a new hierarchy of port networks. This article aims to establish the dynamics of this process based on illustrative cases in Asia, South America, and Europe. Findings reveal spatial factors to include a cluster of small ports with minimal sailing distance within a given range, suitable channel and berth depth, and ideally high capacity inland links. From the economic perspective, demand-side factors include a local captive market and aggregated demand to be captured from other ports, while supply-side factors include diseconomies of scale at traditional hubs, an increase in direct services, an increase in large feeder vessels calling from first-tier hubs which are then transhipped to smaller feeders for serving local ports, and an increase in overland servicing of local smaller ports. From a strategic perspective, vertical and horizontal integration in the shipping sector has produced extensive network economies, whereby shipping lines look to create group-specific port hierarchies, enhanced in the presence of aggressive management strategies and supportive policies. This finding suggests that proactive port stakeholders can in certain circumstances seize the opportunity to capture this role within their port range.     

Cruise port centrality and spatial patterns of cruise shipping in the Asian market

This paper investigates the centrality of cruise ports in the Asian cruise shipping market while proposing the hubs and authorities centrality (HACC) metric as a directional synthesis of the hubs centrality and authorities centrality to explore cyclical and directional features of centrality in the cruise shipping network. With the development of the cruise shipping industry, research has been actively conducted with a particular focus on identifying the characteristics of hub ports. This paper employs social network analysis to investigate the HACC which is originally developed for analyzing the cruise port centrality problem. Empirical study implies that Ho Chi Minh City, Hong Kong, Nagasaki, Penang, Phuket, Port Klang, Shanghai, and Singapore (in alphabetical order) reflects particulars of cruise hub ports. One of the exceptional results of this paper is Ho Chi Minh City, Penang, Phuket, and Port Klang have demonstrated high HACC (refers to hub ports) while limited degree and betweenness centrality. In contrast, Busan and Keelung are not classified as hub ports.     

Strategic fleet size planning for maritime refrigerated containers

In the present economic climate, it is often the case that profits can only be improved, or for that matter maintained, by improving efficiency and cutting costs. This is particularly notorious in the shipping business, where it has been seen that the competition is getting tougher among carriers, thus alliances and partnerships are resulting for cost effective services in recent years. In this scenario, effective planning methods are important not only for strategic but also operating tasks, covering their entire transportation systems. Container fleet size planning is an important part of the strategy of any shipping line. This paper addresses the problem of fleet size planning for refrigerated containers, to achieve cost-effective services in a competitive maritime shipping market. An analytical model is first discussed to determine the optimal size of an own dry container fleet. Then, this is extended for an own refrigerated container fleet, which is the case when an extremely unbalanced trade represents one of the major investment decisions to be taken by liner operators. Next, a simulation model is developed for fleet sizing in a more practical situation and, by using this, various scenarios are analysed to determine the most convenient composition of refrigerated fleet between own and leased containers for the transpacific cargo trade.     

基于遗传算法的编队条件下舰船修理周期结构优化

舰船的部署和修理活动在全寿命期内是按其修理周期结构进行,而编队的使用则需要编队内各舰艇的修理周期结构的相互配合,通过组合优化各舰艇的修理周期结构,可以使编队拥有更多的部署时间。在舰船修理周期结构的定量描述模型基础上,构建了编队的修理调度模型,并采用遗传算法对编队的部署能力进行了优化分析。实例分析结果表明:优化后编队的部署时间可达到近110个月,相对于未优化前提高了50个月。     

Ship scheduling and container shipment planning for liners in short-term operations

Good short-term ship scheduling and container shipment planning are very important for liner operations; however, in Taiwan, most such carriers currently utilize a trial-and-error process. In this study, we employ network flow techniques to construct a model for such activities. A solution algorithm, based on Lagrangian relaxation, a subgradient method, and a heuristic for the upper-bound solution, is developed to solve the model. To demonstrate and to test how well the model and the solution algorithm apply in the real world, we performed a case study using operating data from a major Taiwanese marine shipping company. The test results show that the model and the solution algorithm could be useful references for ship scheduling and container shipment planning.