Papers by Miquel Angel Pïera
Simulation Practice and Theory, 1998
Very often. systems consist of subsystems which may be independently described. Object oriented m... more Very often. systems consist of subsystems which may be independently described. Object oriented modelling languages, as Dymola and Omola. allow models to be structured in independent submodels as systems are structured in subsystems. However, it is not an easy task to derive a mathematical model, suitable for simulation environments, from such a representation.
IEEE Transactions Automation Science and Engineering, 2012
It is widely accepted that new production scheduling tools are playing a key role in flexible man... more It is widely accepted that new production scheduling tools are playing a key role in flexible manufacturing systems to improve their performance by avoiding idleness machines while minimizing set-up times penalties, reducing penalties for do not delivering orders on time, etc. Since manufacturing scheduling problems are NP-hard, there is a need of improving scheduling methodologies to get good solutions within low CPU time. Lagrangian Relaxation (LR) is known for handling large-scale separable problems, however, the convergence to the optimal solution can be slow. LR needs customized parametrization, depending on the scheduling problem, usually made by an expert user. It would be interesting the use of LR without being and expertise, i.e., without difficult parameters tuning. This paper presents innovative approaches on the LR method to be able to develop a tool capable of solve scheduling problems applying the LR method without requiring a deep expertise on it. First approach is the improvement of an already existing method which use Constraint Programming (CP) to obtain better primal cost convergence. Second approach is called Extended Subgradient Information (ESGI) and it speed up the dual cost convergence. Finally, a set of step size rules for the Subgradient (SG) method are compared to choose the most appropriate rule depending on the scheduling problem. Test results demonstrate that the application of CP and ESGI approaches, together with LR and the selected step size rule depending on the problem, generates better solutions than the LR method by itself.
This paper presents a new approach for merging multiple aircraft flows in a Terminal Maneuvering ... more This paper presents a new approach for merging multiple aircraft flows in a Terminal Maneuvering Area (TMA). This work is motivated by the current overloaded airspace near large airports and the need of more efficient methods to help controllers. Some attempts to alleviate airspace congestion such as the minimum spacing requirements, negotiation of voluntary reductions in scheduled service, and the construction of additional runways at major airports have been done. Even though, more fundamental changes are needed to improve the use of available air capacity. Present research consists of a new approach to optimize a set of aircraft planned to land at a given airport; it is proposed to merge the incoming flows from different routes by mean of speed and path changes. Due to the high combinatoric induced by such a problem, a stochastic optimization algorithm has been developed in order to propose to each aircraft a new route and speed profile. Those changes aim to remove conflicts at merging points and to maintain separation of aircraft following the same route link according to their wake turbulence constraint. The optimization criteria is based on the minimum deviation from the initial path planning. This algorithm has been successfully applied to Gran Canaria airport in Spain with real traffic demand samples for which conflict free flow merging is produced smoothly with optimal runway feeding.
Transactions of The Society for Modeling and Simulation International, 2004
Abstract Simulation models have proved to be useful for examining the performance of different sy... more Abstract Simulation models have proved to be useful for examining the performance of different system configurations and/or alternative operating procedures for complex logistic or manufacturing systems. However, when applying simulation techniques to increase the performance of those systems, several limitations arise due to their inability to evaluate more than a fraction of the immense range of options available. Simulation-optimization is one of the most popular approaches to improve the use of simulation models as a tool to obtain ...
The picking process is a critical supply chain component for many companies. A proper warehouse c... more The picking process is a critical supply chain component for many companies. A proper warehouse configuration, storage policy, trays replenishment policy, and other factors are also important to reduce not only the delivery time, but also increase productivity while maintaining quality factors at competitive costs. This paper presents an integrated approach to tackle the complexity of warehouse redesign under several space and quality factor constraints. The proposed design methodology integrates warehouse layout configuration, storage policy, replenishment policy, picking policy, routing policy and also trays and shelves sizes design. As a result of the proposed strategy, considerable savings on resource costs (equipment and workers) can be achieved.
• Mathematical Model for TMA optimization has been developed • Optimization Algorithm based Artif... more • Mathematical Model for TMA optimization has been developed • Optimization Algorithm based Artificial Evolution has been implemented • Such algorithm has been successfully applied to Canaria airport in Spain with real traffic demand samples.
Transactions of The Society for Modeling and Simulation International, 2010
Society for Modeling and Simulation International (SCS) ... Mercedes Narciso Miquel A. Piera Depa... more Society for Modeling and Simulation International (SCS) ... Mercedes Narciso Miquel A. Piera Departament de Telecomunicació i Enginyeria de Sistemes, ETSE (Edifici Q), Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona, Spain [email protected] ...
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Papers by Miquel Angel Pïera