Browsing by Subject "Cargo applications"

Filter results by typing the first few letters
Now showing 1 - 2 of 2
  • Thumbnail Image
    ItemOpen Access
    A hub covering network design problem for cargo applications in Turkey
    (Palgrave Macmillan, 2009) Alumur, S.; Kara, B. Y.
    Hub location problems involve locating hub facilities and allocating demand nodes to hubs in order to provide service between origin-destination pairs. In this study, we focus on cargo applications of the hub location problem. Through observations from the Turkish cargo sector, we propose a new mathematical model for the hub location problem that relaxes the complete hub network assumption. Our model minimizes the cost of establishing hubs and hub links, while designing a network that services each origin-destination pair within a time bound. We formulate a single-allocation hub covering model that permits visiting at most three hubs on a route. The model is then applied to the realistic instances of the Turkish network and to the Civil Aeronautics Board data set.
  • Thumbnail Image
    ItemOpen Access
    Routing and scheduling decisions in the hierarchical hub location problem
    (Elsevier, 2014) Dükkancı, Okan; Kara, Bahar Y.
    Hubs are facilities that consolidate and disseminate flow in many-to-many distribution systems. The hub location problem considers decisions that include the locations of hubs in a network and also the allocations of the demand (non-hub) nodes to these hubs. We propose a hierarchical multimodal hub network. Based on this network, we define a hub covering problem with a service time bound. The hierarchical network consists of three layers. We consider two different structures: ring-star-star (RSS) and ring-ring-star (RRS). The multimodal network has three different types of vehicles in each layer: airplanes, large trucks and small trucks. For the proposed problems (RSS and RRS), we present and strengthen two mathematical models with some variable fixing rules and valid inequalities. We conduct the computational analysis over the Turkish network and the CAB data sets.