Faunhofer Project Center for Production Management and Informatics PMI

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  • Publication
    An inverse economic lot-sizing approach to eliciting supplier cost parameters
    ( 2014)
    Egri, Péter
    ;
    Kis, Tamás
    ;
    Kovács, András
    ;
    Váncza, József
    Recent literature on supply chain coordination offers a wide range of game theoretic and optimization approaches that ensure efficient planning in the supply chain, but assume that the involved parties have complete information about each other. However, in reality, complete information is rarely available, and those models alone do not present any incentive for the parties to reveal their private information, e.g., the cost parameters that they use when solving their planning problems. This paper proposes an inverse lot-sizing model for eliciting the cost parameters of a supplier from historic demand vs. optimal delivery lot-size pairs, gathered during repeated earlier encounters. It is assumed that the supplier solves a single-item, multi-period, uncapacitated lot-sizing problem with backlogs to optimality to calculate its lot-sizes, and the buyer is aware of this fact. The inverse lot-sizing problem is reformulated to an inverse shortest path problem, which is, in tu rn, solved as a linear program. This model is used to compute the ratios of the supplier's cost parameters, i.e., the setup, the holding, and the backlog cost parameters consistent with all the historic samples. The elicited cost parameters can be used as input for various game theoretic or bilevel optimization models for supply chain coordination. Computational experiments on randomly generated problem instances indicate that the approach is very efficient in predicting future supplier actions from the historic records.
  • Publication
    Planning of remote laser welding processes
    ( 2013)
    Erdös, Gábor
    ;
    Kemény, Zsolt
    ;
    Kovács, András
    ;
    Váncza, József
    The paper discusses the technical background of the remote laser welding (RLW) technology, its novel opportunities and implications for planning processes. Our ultimate goal is to develop a complete off-line programming toolbox for RLW which can provide an automated method for computing close-to-optimal robot programs. We suggest a workflow for the complete planning process, and propose new models and algorithms for solving the sequencing of welding tasks in conjunction with path planning, as well as for generating the inverse kinematics of the robot. The paper summarizes results of first computational experiments in an automotive case study using an industrial robot. The proposed method leads to a substantial reduction in the cycle time of the welding operation compared to an earlier approach.
  • Publication
    Designing cooperation mechanisms for supply chains
    ( 2012)
    Váncza, József
    ;
    Egri, Péter
    The paper defines generic requirements towards cooperative planning in the nucleus of any supply network that is constituted by a pair of autonomous manufacturer and supplier who possess asymmetric information on demand forecast and costs, respectively. Then a novel way is suggested for investigating this problem by means of the apparatus of mechanism design. The analysis results in some provable generic properties as for efficiency and truthfulness, and shows the impossibility of fair cost and profit sharing. Further on, design principles towards a payment scheme are devised that provide incentive for the partners to cooperate in order to minimize costs. This payment can be considered the price for a flexible supply service. As examples, the generic framework is instantiated with two particular cooperative supply mechanisms.
  • Publication
    Robust production control against propagation of disruptions
    ( 2011)
    Tolio, Tullio
    ;
    Urgo, Marcello
    ;
    Váncza, József
    In hierarchical production control systems, planning decides on capacities and operations so as to meet demand, while scheduling should guarantee the execution of production plans even in face of uncertainties. The management practice advocates rolling horizon approaches despite the danger of plan nervousness. We propose a novel framework to handle uncertainties closer to the root of their sources, when scheduling local resources. The method keeps the complexity of planning and scheduling at bay and stops the propagation of local disruptions to other resources. The paper presents the theoretical model, the solution technique, and shows their applicability on a case study taken from the tool industry.
  • Publication
    Cooperative and responsive manufacturing enterprises
    ( 2011)
    Váncza, József
    ;
    Monostori, László
    ;
    Lutters, D.
    ;
    Kumara, S.R.
    ;
    Tseng, M.
    ;
    Valckenaers, P.
    ;
    Brussel, H. van
    The paper discusses manufacturing enterprises' compelling challenges that are directly stemming from generic conflicts between competition and cooperation, local autonomy and global behavior, design and emergence, planning and reactivity, uncertainty and a plethora of information. Responses in product and service design, organization of production networks, planning and management of operations, as well as production control are surveyed. As illustrated through industrial case studies, production engineering should integrate a rich body of interdisciplinary results together with contemporary information and communication technologies in order to facilitate cooperation and responsiveness that are vital in competitive, sustainable manufacturing.