Gary Froyland

An Integrated Scenario-Based Approach for Robust Aircraft Routing, Crew Pairing and Re-timing.

  • Michelle Dunbar
  • Gary Froyland
  • Cheng-Lung Wu
    • Categories Airline Optimization Tags , , ,

    For reasons of tractability, the airline scheduling problem has traditionally been sequentially decomposed into various stages (eg. schedule generation, fleet assignment, aircraft routing, and crew pairing), with the decisions from one stage imposed upon the decision making process in subsequent stages. Whilst this approach greatly simplifies the solution process, it unfortunately fails to capture the … Read more

    Solving mixed integer nonlinear programming problems for mine production planning with stockpiling

  • Andreas Bley
  • Natashia Boland
  • Gary Froyland
  • Mark Zuckerberg
    • Categories (Mixed) Integer Nonlinear Programming, Production and Logistics Tags

    The open-pit mine production scheduling problem has received a great deal of attention in recent years, both in the academic literature, and in the mining industry. Optimization approaches to strategic planning for mine exploitation have become the industry standard. However most of these approaches focus on extraction sequencing, and don’t consider the material flow after … Read more

    The recoverable robust tail assignment problem

  • Gary Froyland
  • Stephen J. Maher
  • Cheng-Lung Wu
    • Categories Airline Optimization, Robust Optimization Tags , ,

    Schedule disruptions are commonplace in the airline industry with many flight-delaying events occurring each day. Recently there has been a focus on introducing robustness into airline planning stages to reduce the effect of these disruptions. We propose a recoverable robustness technique as an alternative to robust optimisation to reduce the effect of disruptions and the … Read more

    Robust Airline Schedule Planning: Minimizing Propagated Delay in an Integrated Routing and Crewing Framework

  • Michelle Dunbar
  • Gary Froyland
  • Cheng-Lung Wu
    • Categories Airline Optimization Tags , ,

    To retain a degree of tractability, the airline scheduling problem has traditionally been sequentially decomposed into various stages (eg. schedule generation, fleet assignment, aircraft routing, and crew pairing), with the decisions from one stage imposed upon the decision making process in subsequent stages. Whilst this approach greatly simpli es the solution process, it unfortunately fails to … Read more

    Clique-based facets for the precedence constrained knapsack problem

  • Andreas Bley
  • Natashia Boland
  • Gary Froyland
  • Renata Sotirov
  • Christopher Fricke
    • Categories Cutting Plane Approaches Tags , ,

    We consider a knapsack problem with precedence constraints imposed on pairs of items, known as the precedence constrained knapsack problem (PCKP). This problem has applications in manufacturing and mining, and also appears as a subproblem in decomposition techniques for network design and related problems. We present a new approach for determining facets of the PCKP … Read more

    A Multistage Stochastic Programming Approach to Open Pit Mine Production Scheduling with Uncertain Geology

  • Natashia Boland
  • Gary Froyland
  • Irina Dumitrescu
    • Categories Applications - OR and Management Sciences, Integer Programming, Stochastic Programming Tags , , ,

    The Open Pit Mine Production Scheduling Problem (OPMPSP) studied in recent years is usually based on a single geological estimate of material to be excavated and processed over a number of decades. However techniques have now been developed to generate multiple stochastic geological estimates that more accurately describe the uncertain geology. While some attempts have … Read more

    A strengthened formulation for the open pit mine production scheduling problem

  • Natashia Boland
  • Gary Froyland
  • Christopher Fricke
    • Categories Applications - Science and Engineering Tags , ,

    We present a strengthened integer programming formulation for the open pit mine production scheduling problem, where the precedence and production constraints are combined to form 0-1 knapsack inequalities. Addition of corresponding knapsack cover inequalities decreases the computational requirements to obtain the optimal integer solution, in many cases by a significant margin. Citation The University of … Read more

    Clique-based facets for the precedence constrained knapsack problem

  • Andreas Bley
  • Natashia Boland
  • Gary Froyland
  • Renata Sotirov
  • Christopher Fricke
    • Categories 0-1 Programming, Polyhedra

    We consider a knapsack problem with precedence constraints imposed on pairs of items, known as the precedence constrained knapsack problem (PCKP). This problem has applications in management and machine scheduling, and also appears as a subproblem in decomposition techniques for network design and other related problems. We present a new approach for determining facets of … Read more