54 research outputs found

    Investigating a Hybrid Metaheuristic For Job Shop Rescheduling

    Get PDF
    Previous research has shown that artificial immune systems can be used to produce robust schedules in a manufacturing environment. The main goal is to develop building blocks (antibodies) of partial schedules that can be used to construct backup solutions (antigens) when disturbances occur during production. The building blocks are created based upon underpinning ideas from artificial immune systems and evolved using a genetic algorithm (Phase I). Each partial schedule (antibody) is assigned a fitness value and the best partial schedules are selected to be converted into complete schedules (antigens). We further investigate whether simulated annealing and the great deluge algorithm can improve the results when hybridised with our artificial immune system (Phase II). We use ten fixed solutions as our target and measure how well we cover these specific scenarios

    How Fitch-Margoliash Algorithm can Benefit from Multi Dimensional Scaling

    Get PDF
    Whatever the phylogenetic method, genetic sequences are often described as strings of characters, thus molecular sequences can be viewed as elements of a multi-dimensional space. As a consequence, studying motion in this space (ie, the evolutionary process) must deal with the amazing features of high-dimensional spaces like concentration of measured phenomenon

    A Classification of Hyper-heuristic Approaches

    Get PDF
    The current state of the art in hyper-heuristic research comprises a set of approaches that share the common goal of automating the design and adaptation of heuristic methods to solve hard computational search problems. The main goal is to produce more generally applicable search methodologies. In this chapter we present and overview of previous categorisations of hyper-heuristics and provide a unified classification and definition which captures the work that is being undertaken in this field. We distinguish between two main hyper-heuristic categories: heuristic selection and heuristic generation. Some representative examples of each category are discussed in detail. Our goal is to both clarify the main features of existing techniques and to suggest new directions for hyper-heuristic research

    Jostle for position: local improvement for irregular cutting patterns

    No full text
    This paper introduces a new improvement heuristic for irregular cutting and packing problems. The method is based on a small number of repetitions of any leftmost placement policy and is particularly effective in situations where computation time is strictly limited but exceeds that required for a single pass approach. Both the algorithm and the geometry required for implementation are described in full and the results of computational experiments on a variety of data are presented. These results show that the algorithm is an effective technique for producing good packings
    corecore