Barış Yıldız

Hub Network Design Problem with Capacity, Congestion and Stochastic Demand Considerations

  • Vedat Bayram
  • Barış Yıldız
  • M. Saleh Farham
    • Categories Second-Order Cone Programming, Stochastic Programming, Transportation Tags , , , , , , ,

    We introduce the hub network design problem with congestion, capacity, and stochastic demand considerations (HNDC), which generalizes the classical hub location problem in several directions. In particular, we extend state-of-the-art by integrating capacity acquisition decision and congestion cost effect into the problem and allowing dynamic routing for origin-destination pairs. Connecting strategic and operational level decisions, … Read more

    A Learning Based Algorithm for Drone Routing

  • Umut Ermağan
  • Barış Yıldız
  • Sibel Salman
    • Categories Applications - OR and Management Sciences Tags , , ,

    We introduce a learning based algorithm to solve the drone routing problem with recharging stops that arises in many applications such as precision agriculture, search and rescue and military surveillance. The heuristic algorithm, namely Learn and Fly (L\&F), learns from the features of high quality solutions to optimize recharging visits, starting from a given Hamiltonian … Read more

    Hub Location and Route Dimensioning: Strategic and Tactical Intermodal Transportation Hub Network Design

  • Oya Ekin Karasan
  • Hande Yaman
  • Barış Yıldız
    • Categories Applications - OR and Management Sciences, Combinatorial Optimization, Transportation Tags , , , , ,

    We propose a novel hub location model that jointly eliminates the traditional assumptions on the structure of the network and on the discount due to economies of scale in an effort to better reflect real-world logistics and transportation systems. Our model extends the hub literature in various facets: instead of connecting non-hub nodes directly to … Read more

    Pricing for Delivery Time Flexibility

  • Martin Savelsbergh
  • Barış Yıldız
    • Categories Dynamic Programming, Supply Chain Management, Transportation Tags , , , ,

    We study a variant of the multi-period vehicle routing problem, in which a service provider offers a discount to customer in exchange for delivery flexibility. We establish theoretical properties and empirical insights regarding the intricate and complex relation between the benefit from additional delivery flexibility, the discounts offered to customers to gain additional delivery flexibility, … Read more

    Optimizing Package Express Operations in China

  • Martin Savelsbergh
  • Barış Yıldız
    • Categories Airline Optimization, Combinatorial Optimization, Transportation Tags , , ,

    We explore optimization models to support the planning and operations functions at package express carriers in China. The models simultaneously consider ground and air transportation, company-owned and purchased capacity, multiple service products, and shipments becoming available throughout the day. An extensive computational study using real-life data shows the efficacy of the models, provides insights into … Read more

    Decomposition Branching for Mixed Integer Programming

  • Natashia Boland
  • Martin Savelsbergh
  • Barış Yıldız
    • Categories (Mixed) Integer Linear Programming

    We introduce a novel and powerful approach for solving certain classes of mixed integer programs (MIPs): decomposition branching. Two seminal and widely used techniques for solving MIPs, branch-and-bound and decomposition, form its foundation. Computational experiments with instances of a weighted set covering problem and a regionalized p-median facility location problem with assignment range constraints demonstrate … Read more

    Provably High-Quality Solutions for the Meal Delivery Routing Problem

  • Martin Savelsbergh
  • Barış Yıldız
    • Categories Integer Programming, Optimization of Systems modeled by PDEs, Transportation Tags , , , , ,

    Online restaurant aggregators with integrated meal delivery networks have become more common and more popular in the past few years. Meal delivery is arguably the ultimate challenge in last mile logistics: a typical order is expected to be delivered within an hour (much less if possible), and within minutes of the food becoming ready. We … Read more