Production and Logistics

Scheduling optimization of a real flexible job shop including side constraints regarding maintenance, fixtures, and night shifts

  • Torgny Almgren
  • Michael Patriksson
  • Ann-Brith Strömberg
  • Karin Thörnblad
    • Categories (Mixed) Integer Linear Programming, Production and Logistics, Scheduling Tags , , , , ,

    We present a generic iterative scheduling procedure for the scheduling of a real flexible job shop, the so-called multitask cell at GKN Aerospace Engine Systems in Sweden. A time-indexed formulation of the problem is presented including side constraints regarding preventive maintenance, fixture availability, and unmanned night shifts. This paper continues the work in Thörnblad et … Read more

    A competitive iterative procedure using a time-indexed model for solving flexible job shop scheduling problems

  • Torgny Almgren
  • Michael Patriksson
  • Ann-Brith Strömberg
  • Karin Thörnblad
    • Categories (Mixed) Integer Linear Programming, Production and Logistics, Scheduling Tags , , , , , ,

    We investigate the efficiency of a discretization procedure utilizing a time-indexed mathematical optimization model for finding accurate solutions to flexible job shop scheduling problems considering objectives comprising the makespan and the tardiness of jobs, respectively. The time-indexed model is used to find solutions to these problems by iteratively employing time steps of decreasing length. The … Read more

    Approximate Dynamic Programming for a Class of Long-Horizon Maritime Inventory Routing Problems

  • Myun-Seok Cheon
  • George L. Nemhauser
  • Dimitri J. Papageorgiou
  • Joel Sokol
    • Categories Production and Logistics, Supply Chain Management, Transportation Tags , , , ,

    We study a deterministic maritime inventory routing problem with a long planning horizon. For instances with many ports and many vessels, mixed-integer linear programming (MIP) solvers often require hours to produce good solutions even when the planning horizon is 90 or 120 periods. Building on the recent successes of approximate dynamic programming (ADP) for road-based … Read more

    Robust Optimization of Sums of Piecewise Linear Functions with Application to Inventory Problems

  • Amir Ardestani-Jaafari
  • Erick Delage
    • Categories (Mixed) Integer Linear Programming, Production and Logistics, Robust Optimization Tags , , , , , ,

    Robust optimization is a methodology that has gained a lot of attention in the recent years. This is mainly due to the simplicity of the modeling process and ease of resolution even for large scale models. Unfortunately, the second property is usually lost when the cost function that needs to be robustified is not concave … Read more

    Equipment Selection for Surface Mining: A Review

  • Christina Burt
  • Louis Caccetta
    • Categories Production and Logistics Tags , , , ,

    One of the challenging problems for surface mining operation optimization is choosing the optimal truck and loader fleet. This problem is the Equipment Selection Problem (ESP). In this paper, we describe the ESP in the context of surface mining. We discuss related problems and applications. Within the scope of both the ESP and related problems, … Read more

    Decentralised Shared Resource Constraint Scheduling with Confidentiality Protection

  • Christine O'Keefe
  • Gaurav Singh
    • Categories Production and Logistics, Scheduling, Supply Chain Management Tags , , , ,

    As resources become scarce and expensive, it has become increasingly important for players in a decentralised supply chain to collaborate. One of the main challenges in collaboration is to find close to globally optimal solutions without sharing individual player’s private data. Taking a decentralised resource constrained scheduling problem as an example we present a methodology … Read more

    Public Facility Location Using Dispersion, Population, and Equity Criteria

  • Rajan Batta
  • Miguel A. Lejeune
  • Srinivas Prasad
    • Categories Facility Planning and Design, Production and Logistics Tags , ,

    Administrators/Decision Makers (DMs) responsible for making locational decisions for public facilities have many other overriding factors to consider that dominate traditional OR/MS objectives that relate to response time. We propose that an appropriate role for the OR/MS analyst is to help the DMs identify a good set of solutions rather than an optimal solution that … Read more

    Effectiveness-Equity Models for Facility Location Problems on Tree Networks

  • Miguel A. Lejeune
  • Srinivas Prasad
    • Categories Convex Optimization, Multi-Criteria Optimization, Production and Logistics

    We propose models to investigate effectiveness-equity tradeoffs in tree network facility location problems. We use the commonly used median objective as a measure of effectiveness, and the Gini index as a measure of (in)equity, and formulate bicriteria problems involving these objectives. We develop procedures to identify an efficient set of solutions to these problems, analyze … 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

    Minimum Concave Cost Flow Over a Grid Network

  • Shabbir Ahmed
  • Qie He
  • George L. Nemhauser
    • Categories Combinatorial Optimization, Network Optimization, Production and Logistics Tags , ,

    The minimum concave cost network flow problem (MCCNFP) is NP-hard, but efficient polynomial-time algorithms exist for some special cases such as the uncapacitated lot-sizing problem and many of its variants. We study the MCCNFP over a grid network with a general nonnegative separable concave cost function. We show that this problem is polynomially solvable when … Read more