Now showing items 1-17 of 17

    • A branch and cut algorithm for the inventory routing problem 

      Mahmutoğulları, Özlem (Bilkent University, 2019-07)
      The inventory routing problem arises in vendor managed systems where products are distributed from a supplier to a set of retailers by a homogeneous eet of capacitated vehicles. The routes of the vehicles and the ...
    • A branch-and-cut algorithm for the hub location and routing problem 

      Rodríguez-Martín, I.; Salazar-González, J-J.; Yaman, H. (Elsevier, 2014)
      We study the hub location and routing problem where we decide on the location of hubs, the allocation of nodes to hubs, and the routing among the nodes allocated to the same hubs, with the aim of minimizing the total ...
    • A branch-and-cut algorithm for two-level survivable network design problems 

      Rodríguez-Martín, I.; Salazar-González, J-J.; Yaman, H. (Elsevier, 2016)
      This paper approaches the problem of designing a two-level network protected against single-edge failures. The problem simultaneously decides on the partition of the set of nodes into terminals and hubs, the connection of ...
    • Comparison of the formulations for a hub-and-spoke network design problem under congestion 

      Kian R.; Kargar K. (Elsevier, 2016)
      In this paper, we study the hub location problem with a power-law congestion cost and propose an exact solution approach. We formulate this problem in a conic quadratic form and use a strengthening method which rests on ...
    • Formulations and valid inequalities for the heterogeneous vehicle routing problem 

      Yaman, H. (Springer, 2006)
      We consider the vehicle routing problem where one can choose among vehicles with different costs and capacities to serve the trips. We develop six different formulations: the first four based on Miller-Tucker-Zemlin ...
    • Hierarchical multimodal hub location problem with time-definite deliveries 

      Alumur, S. A.; Yaman, H.; Kara, B. Y. (Elsevier, 2012)
      Hierarchical multimodal hub location problem is a cost-minimizing hub covering problem where two types of hubs and hub links, accounting for ground and air transportation, are to be established, while ensuring time-definite ...
    • The integer knapsack cover polyhedron 

      Yaman, H. (Society for Industrial and Applied Mathematics, 2007)
      We study the integer knapsack cover polyhedron which is the convex hull of the set of vectors x ∈ ℤ+ n that satisfy C T x ≥ b, with C ∈ ℤ++ n and 6 ∈ ℤ++. We present some general results about the nontrivial facet-defining ...
    • An intermodal multicommodity routing problem with scheduled services 

      Ayar, B.; Yaman, H. (2012)
      We study a multicommodity routing problem faced by an intermodal service operator that uses ground and maritime transportation. Given a planning horizon, a set of commodities to be picked up at their release times and to ...
    • k-node-disjoint hop-constrained survivable networks: polyhedral analysis and branch and cut 

      Diarrassouba, I.; Mahjoub, M.; Mahjoub, A. R.; Yaman, H. (Springer-Verlag France, 2018)
      Given a graph with weights on the edges, a set of origin and destination pairs of nodes, and two integers L ≥ 2 and k ≥ 2, the k-node-disjoint hop-constrained network design problem is to find a minimum weight subgraph of ...
    • The latest arrival hub location problem for cargo delivery systems with stopovers 

      Yaman, H.; Kara, B. Y.; Tansel, B. C. (Elsevier, 2007)
      In this paper, we concentrate on the service structure of ground-transportation based cargo delivery companies. The transient times that arise from nonsimultaneous arrivals at hubs (typically spent for unloading, loading, ...
    • Lot sizing with perishable items 

      Arslan, Nazlıcan (Bilkent University, 2019-07)
      We address the uncapacitated lot sizing problem for a perishable item that has a deterministic and fixed lifetime. In the first part of the study, we assume that the demand is also deterministic. We conduct a polyhedral ...
    • Manufacturer's mixed pallet design problem 

      Yaman, H.; Şen, A. (Elsevier, 2008)
      We study a problem faced by a major beverage producer. The company produces and distributes several brands to various customers from its regional distributors. For some of these brands, most customers do not have enough ...
    • New exact solution approaches for the split delivery vehicle routing problem 

      Özbaygın, G.; Karasan, O.; Yaman, H. (Springer Verlag, 2018)
      In this study, we propose exact solution methods for the split delivery vehicle routing problem (SDVRP). We first give a new vehicle-indexed flow formulation for the problem and then a relaxation obtained by aggregating ...
    • The periodic vehicle routing problem with driver consistency 

      Rodríguez-Martín, I.; Salazar-González, J. -J.; Yaman, H. (Elsevier, 2018)
      The Periodic Vehicle Routing Problem is a generalization of the classical capacitated vehicle routing problem in which routes are determined for a planning horizon of several days. Each customer has an associated set of ...
    • The ring/κ-rings network design problem: model and branch-and-cut algorithm 

      Rodríguez-Martín, I.; Salazar-González, J-J.; Yaman, H. (John Wiley & Sons, 2016)
      This article considers the problem of designing a two-level network where the upper level consists of a backbone ring network connecting the so-called hub nodes, and the lower level is formed by access ring networks that ...
    • Time constrained maximal covering salesman problem with weighted demands and partial coverage 

      Ozbaygin, G.; Yaman, H.; Karasan, O. E. (Elsevier Ltd, 2016)
      In a routing framework, it may not be viable to visit every single customer separately due to resource limitations or efficiency concerns. In such cases, utilizing the notion of coverage; i.e., satisfying the demand of ...
    • The vendor location problem 

      Çınar, Y.; Yaman, H. (Elsevier, 2011)
      The vendor location problem is the problem of locating a given number of vendors and determining the number of vehicles and the service zones necessary for each vendor to achieve at least a given profit. We consider two ...