Institute for Systems Research Technical Reports

Permanent URI for this collectionhttp://hdl.handle.net/1903/4376

This archive contains a collection of reports generated by the faculty and students of the Institute for Systems Research (ISR), a permanent, interdisciplinary research unit in the A. James Clark School of Engineering at the University of Maryland. ISR-based projects are conducted through partnerships with industry and government, bringing together faculty and students from multiple academic departments and colleges across the university.

Browse

Author: search.filters.author.Ioannou, GeorgeSubject: search.filters.subject.manufacturing

Search Results

Now showing 1 - 6 of 6
  • Thumbnail Image
    Item
    Integrated Manufacturing Facility Design
    (1995) Ioannou, George; Minis, I.; ISR
    This dissertation addresses for the first time the integrated problem of designing the manufacturing shop layout concurrently with its material handling system. Specifically, this study provides a method to derive shop designs that are economic to set up and efficient to operate. In doing so, it considers the following highly interrelated issues: i) The topology of the material flow network, ii) the transporter fleet size and routing, and iii) the layout of the resource groups on the shop floor. The design problem is modeled by a comprehensive mathematical program which captures critical practical concerns such as investment and operational costs, traffic congestion, and transporter capacities. The model is decomposed into three NP- hard subproblems by fixing and/or aggregating variables and constraints. The first subproblem is the generic multi-commodity fixed charge capacitated network design, for which an improved lower bound is derived based on a dual ascent method. This problem is solved by three heuristics that provide near-optimal network designs. The second subproblem concerns the transporter routing, which is a special case of the distance-constrained vehicle routing problem. For the transporter routing problem near-optimal solutions are derived in polynomial time by two efficient heuristics with bounded worst-case performance. Tight lower bounds are provided by solutions to the assignment problem. An integrated method combines the most effective heuristics for the material handling system design subproblems with a simulated annealing scheme to solve the global shop design problem. Our novel approach addresses simultaneously most major decisions involved in manufacturing shop design, and provides globally near optimal solutions. The method is applied to the redesign of the shop of a large manufacturer, and generates a particularly attractive production system design reducing significantly both investment and operational costs, while providing for smooth system operation.
  • Thumbnail Image
    Item
    An Integrated Model for Manufacturing Shop Design
    (1995) Ioannou, George; Minis, Ioannis; ISR
    This paper presents an integer programming formulation for the manufacturing shop design problem, which integrates decisions concerning the layout of the resource groups on the shop floor with the design of the material handling system. The model reflects critical practical design concerns including the capacity of the flow network and of the transporters, and the tradeoff between fixed (construction and acquisition) and variable (operational) costs. For realistic industrial cases, the size of the problem prevents the solution through explicit or implicit enumeration schemes. The paper addresses this limitation by decomposing the global model into its natural components. The resulting submodels are shown to be standard problems of operations research. The decomposition approach provides ways to solve the integrated shop design problem in an effective manner.
  • Thumbnail Image
    Item
    Current Research on Manufacturing Shop and Material Handling System Design
    (1995) Ioannou, George; Minis, Ioannis; ISR
    The importance of the manufacturing shop design in the successful operation of a production system is well known and as a result, significant research has been devoted to this area. This paper reviews important literature in various aspects of manufacturing shop design including layout, material flow path design, and transporter fleet sizing and routing. In addition, the paper focuses on contributions to integration issues such as the design for operation of material handling systems, and the concurrent design of the shop layout and the transportation system. Research studies in these areas are critically examined, and emerging opportunities for research are identified.
  • Thumbnail Image
    Item
    Minimization of Acquisition and Operational Costs in Horizontal Material Handling System Design
    (1995) Herrmann, Jeffrey W.; Ioannou, George; Minis, Ioannis; Proth, J.M.; ISR
    This paper considers the problem of minimizing the fixed cost of acquiring material handling transporters and the operational cost of material transfer in a manufacturing system. This decision problem arises during manufacturing facility design, and is modeled using an integer programming formulation. Two efficient heuristics are developed to solve it. Computational complexity, worst-case performance analysis, and extensive computational tests are provided for both heuristics. The results indicate that the proposed methods are well suited for large-scale manufacturing applications.
  • Thumbnail Image
    Item
    Design of Material Flow Networks in Manufacturing Facilities
    (1994) Herrmann, Jeffrey W.; Ioannou, George; Minis, Ioannis; Nagi, R.; Proth, J.M.; ISR
    In this paper we consider the design of material handling flow paths in a discrete parts manufacturing facility. A fixed-charge capacitated network design model is presented and two efficient heuristics are proposed to determine near-optimal solutions to the resulting NP- hard problem. The heuristics are tested against an implicit enumeration scheme used to obtain optimal solutions for small examples. For more realistic cases, the solutions of the heuristics are compared to lower bounds obtained by either the linear programming relaxation of the mixed integer program, or an iterative dual ascent algorithm. The results obtained indicate that the heuristics provide good solutions in reasonable time on the average. The proposed methodology is applied to design the flow paths of an existing manufacturing facility. The role of the flow path network problem in the integrated shop design is also discussed.
  • Thumbnail Image
    Item
    A Dual Ascent Approach to the Fixed-Charge Capacitated Network Design Problem
    (1994) Herrmann, Jeffrey W.; Ioannou, George; Minis, Ioannis; Proth, J.M.; ISR
    In this paper we consider the problem of constructing a network over which a number of commodities are to be transported. Fixed costs are associated to the construction of network arcs and variable costs are associated to routing of commodities. In addition, one capacity constraint is related to each arc. The problem is to determine a network design that minimizes the total cost; i.e. it balances the construction and operating costs. A dual ascent procedure for finding improved lower bounds and near- optimal solutions for the fixed-charge capacitated network design problem is proposed. The method is shown to generate tighter lower bounds than the linear programming relaxation of the problem.