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.

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Author: search.filters.author.Harhalakis, GeorgeSubject: search.filters.subject.group technology

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Now showing 1 - 8 of 8
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    A Practical Method for Design of Hybrid-Type Production Facilities
    (1994) Harhalakis, George; Lu, Thomas C.; Minis, Ioannis; Nagi, R.; ISR
    A comprehensive methodology for the design of hybrid-type production shops that comprise both manufacturing cells and individual workcenters is presented. It targets the minimization of the material handling effort within the shop and comprises four basic steps: (1) identification of candidate manufacturing cells, (2) evaluation and selection of the cells to be implemented, (3) determination of the intra-cell layout, and (4) determination of the shop layout. For the cell formation step the ICTMM technique has been enhanced to cater for important practical issues. The layout of each significant cell is determined by a simulated annealing (SA)-based algorithm. Once the sizes and shapes of the selected cells are known, the shop layout is determined by a similar algorithm. The resulting hybrid shop consists of the selected cells and the remaining machines. The methodology has been implemented in an integrated software system and has been applied to redesign the shop of a large manufacturer of radar antennas.
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    Manufacturing Cell Formation Under Random Product Demand
    (1993) Harhalakis, George; Minis, Ioannis; Nagi, R.; ISR
    The performance of cellular manufacturing systems is intrinsically sensitive to demand variations and machine breakdowns. A cell formation methodology that addresses, during the shop design stage, system robustness with respect to product demand variation is proposed. The system resources are aggregated into cells in a manner that minimizes the expected inter-cell material handling cost. The statistical characteristics of the independent demand and the capacity of the system resources are explicitly considered. In the first step of the proposed approach the expected value of the feasible production volumes, which respect resource capacities, are determined. Subsequently, the shop partition that results in near optimal inter cell part traffic is found. The applicability of the proposed approach is illustrated through a comprehensive examples.
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    Hierarchical Modeling Approach for Production Planning
    (1992) Harhalakis, George; Nagi, R.; Proth, J.M.; ISR
    Production management problems are complex owing to large dimensionality, wide variety of decisions of varying scope, focus and time-horizon, and disturbances. A hierarchical approach to these problems is a way to address this complexity, wherein the global problem is decomposed into a series of top-down sub- problems. We advocate that a single planning architecture cannot be employed for all planning problems. We propose a multi-layer hierarchical decomposition which is dependent on the complexity of the problem, and identify the factors influencing complexity. A systematic stepwise design approach for the construction of the hierarchy and inputs required are presented. The subsequent operation of the hierarchy in an unreliable environment is also explained. Aggregation schemes for model reduction have been developed and blended with a time-scale decomposition of activities to provide the theoretical foundation of the architecture. It is also hoped that this methodology can be applied to other such large-scale complex decision making problems.
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    A PDES Model for Microwave Modules
    (1991) Bahadur, Sudhanshu; Harhalakis, George; Hosier, Robert N.; Minis, Ioannis; ISR
    This paper presents a novel application of the Layered Electrical Product (LEP) model of the PDES (Product Data Exchange specification using STEP) standard. All three levels of the LEP model are developed for a typical microwave module (MWM). The latter comprises of a component layer, the artwork, an insulation layer and a ground plane, which is a complex mechanical part. The nature of the ground plane necessitated the enhancement of the first level of the model to include three dimensional topological entities. Consequently, although the artwork and insulation layers are represented in two-and-a-half dimensions, (which is common practice in the case of Printed Wiring Boards), the ground plane is modeled using the three-dimensional PDES Geometrical and Topological models and the Form Features model. Level II includes the electrical entities of the MWM. New conventions that are necessary to represent particular features of the MWM have been proposed and applied. Based on the intention of PDES, design information that is closely related to manufacturing concerns has been represented in Level III of the model. Both the proposed structure and the contents of this level for MWMs are presented. Material specifications, mechanical features, design specifications for the manufacture of joins, and others are included. Finally, potential applications of the LEP model and especially of Level III in automated process planning and producibility assessment are discussed.
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    Class: Computerized LAyout Solutions Using Simulated Annealing
    (1990) Minis, Ioannis; Harhalakis, George; Jajodia, Satish K.; Proth, J.M.; ISR
    A new method (Computerized LAyout Solutions using Simulated annealing - CLASS) that considers the inter-cell and intra-cell layout problems in a cellular manufacturing environment is presented. It addresses the relative placement of equidimensional manufacturing entities within a discrete solution space in an attempt to minimize the total material flow (cost) between these entities. An approach to accommodate the relative sizes of the entities is also presented. The method is based on Simulated Annealing, which has been successfully applied for the solution of combinatorial problems. A major advantage of this technique is the insensitivity of the final solution to the initial conditions. In addition, some important practical issues such as intra-cell layout of machines in pre-determined configurations (e.g. row-wise or circular arrangements), have been addressed. Several comparisons were made with some of the existing approaches for facility layout, such as CRAFT, HC63-66, etc. that yielded results of equal or better quality for each of eight classical test problems.
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    Manufacturing Cell Formation with Multiple, Functionally Identical Machines
    (1990) Minis, Ioannis; Harhalakis, George; Jajodia, Satish K.; ISR
    A comprehensive methodology for the formation of manufacturing cells in an environment consisting of unique as well as multiple, functionally identical machines is presented in this paper. The proposed method presupposes the existence of generic process plans that specify the types of machines required for the manufacture of each part, although more than one machine of the same type may be available in the shop. The production equipment is grouped into manufacturing cells and the manufactured parts are assigned to part families, based on an inter-cell traffic minimization criterion and subject to capacity constraints. Two or more functionally identical machines are included in a cell, only if necessitated by capacity considerations, or traffic minimization arguments. The method also considers both part set- up and run times for the evaluation of the capacity requirements, and uses pallet traffic as opposed to individual part traffic in the minimization criterion.
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    Manufacturing Cell Design Using Simulated Annealing: an Industrial Application
    (1990) Harhalakis, George; Proth, J.M.; Xie, X.L.; ISR
    In this paper, we give a brief summary of simulated annealing procedures used to solve combinatorial optimization problems. We then present the manufacturing cell design problem which consists of designing cells of limited size in order to minimize inter- cell traffic. We show how to use a SA approach to obtain a good, if not optimum, solution to this problem. Finally, we apply this approach to an industrial problem and compare the results to the ones obtained using the so-called twofold heuristic algorithm.
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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.