Browsing by Author "Proth, Jean-Marie"

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    Formation of Manufacturing Cells: An Algorithm for Minimizing the Inter-Cell Traffic.
    (1989) Harhalakis, George; Hilger, Jean; Nagi, R.; Proth, Jean-Marie; ISR
    In this paper, we propose a parametrized algorithm to decompose a manufacturing system into manufacturing cells. The objective is to minimize the inter-cell traffic. The algorithm is based on a proximiq index defined between any two machines and which is conversely proportional to the intensity of the traffic between these machines. We compute a density for each machine. This densiq is defined as the number of machines close to the considered machine in the sense of the previous index. We then group into cells the machines that are in the same high density domains. We finally associate a family of parts to each of the previous cells. A numerical example illustrates this approach
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    Generalization and Implementation of the GP Method to Generate Manufacturing Cell and Part Families.
    (1989) Hilger, Jean; Harhalakis, George; Proth, Jean-Marie; ISR
    We present an algorithm that considers a set of product types and a set of machine types. The algorithm works out a partition of p subsets of product types, called product families, and a partition of q subsets of machine types, called production subsystems such that: either p = q and there exists a one-to-one relationship between and product families production subsystems, or p = q +1 (or q = p +1) and there exists a one-to-one relationship between r product families and production subsystems where r is the minimum value of p and q. The supplementary subset of product (or machine) types has no corresponding subset of machine (or product) types. In both cases the partitions obtained maximize a criterion that is the weighted sum of normalized processing times of each product family in its related production subsystem and the complements of normalized processing times of each product family outside its related production subsystem. In the latter case the supplementary subset of product (or machine) types contains only products that have insignificant processing times (or machines which are only rarely or briefly involved by product transformation). We prove the convergence of our algorithm and give some numerical results. The paper is concluded with the description of an implementation of the algorithm for large data sets.
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    Manufacturing Cell Formation in the Case of Multi-Manufacturing Processes
    (1990) Harhalakis, George; Hilger, Jean; Proth, Jean-Marie; ISR
    The determination of a good decomposition of a manufacturing system into manufacturing cells, when various manufacturing processes are available for each type of product, is addressed in this paper. We propose a simple twofold algorithm. The first part of the algorithm aims at defining the proportion of each product type to manufacture, using each of the available manufacturing processes. The result is a monomanufacturing process problem, i.e. a problem which consists of finding a good decomposition of a manufacturing system into cells when only one manufacturing process is available for each type of product. The second part of the algorithm uses an approach already presented by the authors to solve the monomanufacturing process problem. We also present a numerical example to illustrate our approach.
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    Performance Evaluation of a Hierarchical Production Scheduling Policy for a Single Machine with Earliness and Tardiness
    (1990) Nagi, Rakesh; Harhalakis, George; Proth, Jean-Marie; ISR
    This paper considers the problem of scheduling a given set of jobs on a single machine in order to minimize the total earliness and tardiness costs. The scheduling horizon is divided into elementary periods; jobs have due-dates at the end of these periods. All jobs are assumed initially available. Jobs have unique (weighted) early and tardy penalty functions that are staircase-type. No preemption of jobs is permitted, and idle time may be inserted. This problem is NP-complete. A branch- and-bound scheme that solves the above mentioned problem optimally is presented. We then propose a hierarchical scheduling policy under the assumption that tardiness costs are much greater than earliness costs for all jobs. We also assume that the system if able to meet the production requirements on the average and the scheduling horizon is long enough to absorb cyclicity. The hierarchy is composed of two levels: (i) the high level, and (ii) the low level. The concept of rolling horizon is employed at the high level, which solves the flow control under constraints of no tardiness. The low level, prioritizes jobs resulting from the solution of the high level over a short term horizon. Numerical results relating to the comparison of the performance of this hierarchical policy with the branch-and-bound scheme are presented.