36 research outputs found

    An elitist quantum-inspired evolutionary algorithm for the flexible job-shop scheduling problem

    Get PDF
    The flexible job shop scheduling problem (FJSP) is vital to manufacturers especially in today’s constantly changing environment. It is a strongly NP-hard problem and therefore metaheuristics or heuristics are usually pursued to solve it. Most of the existing metaheuristics and heuristics, however, have low efficiency in convergence speed. To overcome this drawback, this paper develops an elitist quantum-inspired evolutionary algorithm. The algorithm aims to minimise the maximum completion time (makespan). It performs a global search with the quantum-inspired evolutionary algorithm and a local search with a method that is inspired by the motion mechanism of the electrons around an atomic nucleus. Three novel algorithms are proposed and their effect on the whole search is discussed. The elitist strategy is adopted to prevent the optimal solution from being destroyed during the evolutionary process. The results show that the proposed algorithm outperforms the best-known algorithms for FJSPs on most of the FJSP benchmarks

    Combined ship routing and inventory management in the salmon farming industry

    Get PDF
    We consider a maritime inventory routing problem for Norway's largest salmon farmer both producing the feed at a production factory and being responsible for fish farms located along the Norwegian coast. The company has bought two new ships to transport the feed from the factory to the fish farms and is responsible for the routing and scheduling of the ships. In addition, the company has to ensure that the feed at the production factory as well as at the fish farms is within the inventory limits. A mathematical model of the problem is presented, and this model is reformulated to improve the efficiency of the branch-and-bound algorithm and tightened with valid inequalities. To derive good solutions quickly, several practical aspects of the problem are utilized and two matheuristics developed. Computational results are reported for instances based on the real problem of the salmon farmer

    Decision Support for Industrial Engineering and Logistics

    No full text
    International audienc

    Disjunctive and time-indexed formulations for non-preemptive job shop scheduling with resource availability constraints

    No full text
    International audienc

    Multi-objective optimization for Work-In-Process balancing and throughput maximization in global fab scheduling

    No full text
    International audienceThis paper presents a multi-objective optimization approach for global fab scheduling, based on a mathematical model that determines production targets, i.e. product quantities to complete in each operation and each period on a scheduling horizon. The multi-objective approach balances product mix variability minimization and throughput maximization using an ε-constraint approach. For evaluation purposes, the global fab scheduling model is coupled with a generic multi-method simulation model. Numerical experiments conducted on industrial data illustrate the effectiveness of the approach
    corecore