Now showing 1 - 10 of 13
  • Publication
    Robust production planning and control for multi-stage systems with flexible final assembly lines
    ( 2017)
    Gyulai, D.
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    Pfeiffer, A.
    ;
    Monostori, L.
    Production planning of final assembly systems is a challenging task, as the often fluctuating order volumes require flexible solutions. Besides, the calculated plans need to be robust against the process-level disturbances and stochastic nature of some parameters like manual processing times or machine availability. In the paper, a simulation-based optimisation method is proposed that utilises lower level shop floor data to calculate robust production plans for final assembly lines of a flexible, multi-stage production system. In order to minimise the idle times when executing the plans, the capacity control that specifies the proper operatorâtask assignments is also determined. The analysed multi-stage system is operated with a pull strategy, which means that the production at the final assembly lines generates demands for the preceding stages providing the assembled components.
  • Publication
    Decision support solutions for factory and network logistics operations
    ( 2017)
    Ilie-Zudor, E.
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    Kemény, Z.
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    Pfeiffer, A.
    ;
    Monostori, L.
    The paper examines the relationship of decision levels, performance measures and modelling and decision support approaches through the example of two implemented decision support systems for manufacturing and logistics application fields. Aside from highlighting the relevance of decision support for making industrial networks fit for emerging challenges, the relevance of the two presented EU FP7 projects VFF and ADVANCE to the Factories of the Future vision is shown. A discussion of the two projects outlines future research, with particular focus on challenges that arise from integration across levels of the decision hierarchy, within an organisationally heterogeneous network.
  • Publication
    Performance measurement in flow lines â Key to performance improvement
    ( 2016)
    Stricker, N.
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    Pfeiffer, A.
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    Moser, E.
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    Kádár, B.
    ;
    Lanza, G.
    Key Performance Indicators (KPIs) are frequently used for measuring a production systemsâ performance. The selection of KPIs should lead to a set being as small as possible but taking into account all relevant aspects of the system. This paper provides an analytical approach to determine the set of relevant KPIs for specific production lines, allowing for a transparent and complete performance measurement. An LP was formulated for the proposed KPI model and a significant reduction of the number of KPIs used could be realized. The analytical model was tested in a real industrial application.
  • Publication
    Simulation-based production planning and execution control for reconfigurable assembly cells
    ( 2016)
    Gyulai, D.
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    Pfeiffer, A.
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    Kádár, B.
    ;
    Monostori, L.
    In order to meet the continuously changing market conditions and achieve economy of scale, a current trend in the automotive industry is the application of modular reconfigurable assembly systems. Although they offer efficient solution to meet the customers needs, the management of these systems is often a challenging issue, as the continuous advance in the assembly technology introduces new requirements in production planning and control activities. In the paper, a novel approach is introduced that enables the faster introduction of modular assembly cells in the daily production by offering a flexible platform for evaluating the system performance considering dynamic logistics and production environment. The method is aimed at evaluating different modular cell configurations with discrete-event simulation, applying automated model building and centralized simulation model control. Besides, the simulation is linked with the production and capacity planning model of the system in order to implement a cyclic workflow to plan the production and evaluate the system performance in a proactive way, before releasing the plan to the production. The method and the implemented workflow are evaluated within a real case study from the automotive industry.
  • Publication
    Generic data structure and validation methodology for simulation of manufacturing systems
    ( 2016)
    Popovics, G.
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    Pfeiffer, A.
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    Monostori, L.
    In recent years, the analysis and evaluation of manufacturing systemsâ behaviour and their performance became essential. Discrete event simulation (DES) as a digital enterprise technology is an effective tool both in production related decision support processes and in structure or performance analysis of manufacturing systems. Building a DES model of a manufacturing system is a difficult task and requires special competence. Reducing the efforts spent on draft simulation is the aim of an ongoing research which is presented in the paper. The developed framework simplifies and accelerates the process of model building. A production oriented implementation of the ANSI/ISA-95 standard was used by the proposed modelling methodology to define a generic data structure supporting the creation of models without specific knowledge related to the simulation software applied. The data structure enables the development and application of proprietary simulation engines tailored for specific problems.
  • Publication
    Simulation support in construction uncertainty management: A production modelling approach
    ( 2016)
    Pfeiffer, A.
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    Kádár, B.
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    Bohács, G.
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    Gáspár, D.
    The execution of construction projects such as a highway construction or the elevation of a new bridge is a complex, highly equipment-intensive process and are subject to many different uncertainties. This is very similar to the manufacturing execution level in production systems where predefined productions plans and schedules cannot be completely implemented due to unexpected internal and external changes and disturbances. Following this analogy, the paper proposes the application of a discrete-event simulation based method which was already applied in the decision-support for manufacturing control to develop the decision-support in the execution of a construction project where the effects of the deviation from the short-term schedule can be easily and quickly analyzed.
  • Publication
    Manufacturing lead time estimation with the combination of simulation and statistical learning methods
    ( 2016)
    Pfeiffer, A.
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    Gyulai, D.
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    Kádár, B.
    ;
    Monostori, L.
    In the paper, a novel method is introduced for selecting tuning parameters improving accuracy and robustness for multi-model based prediction of manufacturing lead times. Prediction is made by setting up models using statistical learning methods (multivariate regression); trained, validated and tested on log data gathered by manufacturing execution systems (MES). Relevant features, i.e.; the predictors most contributing to the response, are selected from a wider range of system parameters. The proposed method is tested on data provided by a discrete event simulation model (as a part of a simulation-based prediction framework) of a small-sized flow-shop system. Accordingly, log data are generated by simulation experiments, substituting the function of a MES system, while considering several different system settings (e.g.; job arrival rate, test rejection rate).
  • Publication
    Supporting multi-level and robust production planning and execution
    ( 2015)
    Stricker, N.
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    Pfeiffer, A.
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    Moser, E.
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    Kádár, B.
    ;
    Lanza, G.
    ;
    Monostori, L.
    Operating current production systems influenced by the factors of increasing dynamics and volatility poses a need for robustness. Among different enablers for robustness the appropriate ones for specific production systems have to be identified and evaluated. In this cooperative paper multi-objective decision support models will be presented evaluating the best enablers for the levels of production network, plant and shop-floor. The suggested models for the stabilization of the production system's performance under volatile environment use analytical and simulation based approaches on the regarded levels.
  • Publication
    Milkrun vehicle routing approach for shop-floor logistics
    ( 2013)
    Gyulai, D.
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    Pfeiffer, A.
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    Sobottka, T.
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    Váncza, J.
    In large-scale shop floors and manufacturing environment, different transportation systems are applied in order to satisfy the material requirements of the systems. The limited capacity of vehicles and time consumption of the logistics processes require effective vehicle routing approaches so as to support production without glitches. The paper gives an overview of the appropriate models and the most efficient solver algorithms of the vehicle routing problem (VRP), introduces a novel approach that uses a novel initial solution generation heuristics, and presents a local search method to solve the VRP. In order to demonstrate the capabilities of the solution proposed, the implemented software concentrates on the main industrial requirements like quick response, effective layout definition and order handling. A specific layout representation scheme is proposed which ensures interoperability between different factory-, and shop-floor planning software products.
  • Publication
    Execution data connected simulation for production operation planning and control
    ( 2012)
    Kádár, B.
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    Pfeiffer, A.
    ;
    Monostori, L.
    Due to the large number of the resources, the frequent reengineering of manufacturing processes and the often changing product types, the maintenance of the simulation model and the provision of up-to-date input data are almost always difficult. The paper introduces new quantitative analysis method including processing time and batch calculation algorithms applied in the automatic building of discrete-event simulation systems. The simulation model and the mentioned algorithms are both directly interfaced with real execution databases and the overall solution supports the shop-floor managers in making control decisions. The applicability of the elaborated approach is illustrated by the results of experiments relying on real historical data.