Helena Ramalhinho-Lourenço
Pompeu Fabra University
Publications 48
#1Christian Blum (CSIC: Spanish National Research Council)H-Index: 33
#2Angel A. Juan (Open University of Catalonia)H-Index: 25
Last.Thomas Sttzle (ULB: Université libre de Bruxelles)H-Index: 61
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#1Alex Grasas (EADA Business School)H-Index: 6
#2Angel A. Juan (Open University of Catalonia)H-Index: 25
Last.Helena Ramalhinho-Lourenço (UPF: Pompeu Fabra University)H-Index: 17
view all 3 authors...
AbstractIterated Local Search (ILS) is one of the most popular single-solution-based metaheuristics. ILS is recognized by many authors as a relatively simple yet efficient framework able to deal with complex combinatorial optimization problems (COPs). ILS-based algorithms have been successfully applied to provide near-optimal solutions to different COPs in logistics, transportation, production, etc. However, ILS is designed to solve COPs under deterministic scenarios. In some real-life applicati...
25 CitationsSource
#1Angel A. Juan (Open University of Catalonia)H-Index: 25
#2Helena Ramalhinho-Lourenço (UPF: Pompeu Fabra University)H-Index: 17
Last.Quim Castellà (Open University of Catalonia)H-Index: 3
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Iterated local search (ILS) is a powerful framework for developing efficient algorithms for the permutation flow-shop problem (PFSP). These algorithms are relatively simple to implement and use very few parameters, which facilitates the associated fine-tuning process. Therefore, they constitute an attractive solution for real- life applications. In this paper, we discuss some parallelization, parametrization, and randomization issues related to ILS-based algorithms for solving the PFSP. In parti...
40 CitationsSource
#1Alex Grasas (UPF: Pompeu Fabra University)H-Index: 6
#2Jose Caceres-Cruz (Open University of Catalonia)H-Index: 6
Last.Mercè Roca (IBS: International Business School, Germany)H-Index: 1
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In this article we present a Vehicle Routing Problem (VRP) faced by a large distribution company in the Northeast of Spain. The company distributes products from its central facilities to a chain of around 400 stores all over the country. One of the peculiarities of the VRP of this company – which is common among real-life VRPs – is the presence of a heterogeneous fleet where vehicles with different capacities can make multiple trips during a single day. This variant of the problem, which we ref...
4 CitationsSource
#1Angel A. Juan (Open University of Catalonia)H-Index: 25
#2Javier FaulinH-Index: 22
Last.Barry B. Barrios (NU: Northwestern University)H-Index: 8
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This paper discusses the use of probabilistic or randomized algorithms for solving vehicle routing problems with non-smooth objective functions. Our approach employs non-uniform probability distributions to add a biased random behavior to the well-known savings heuristic. By doing so, a large set of alternative good solutions can be quickly obtained in a natural way and without complex configuration processes. Since the solution-generation process is based on the criterion of maximizing the savi...
45 CitationsSource
#1Helena Ramalhinho-Lourenço (UPF: Pompeu Fabra University)H-Index: 17
#2Manuel Mateo Doll (UPF: Pompeu Fabra University)
Last.Angel A. JuanH-Index: 25
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A la hora de poder aplicar algoritmos te oricos a casos reales, no solo resulta conveniente que el algoritmo sea e ciente sino tambi en que sea lo m as comprensible posible y que no requiera de comple- jos procesos de parametrizaci on. Siguiendo esta l ogi- ca, proponemos aqu un algoritmo h brido que reune las caracter sticas anteriores para resolver el proble- ma del Flow-Shop (FSP). El algoritmo, que no re- quire de parametrizaci on alguna, combina estrategias de randomizaci on con una B usque...
La problematica del enrutamiento de vehiculos cobra cada vez mas importancia en el plano empresarial y estatal. Esta area de estudio ha experimentado grandes avances teoricos, pero se ha mantenido a cierta distancia de la practica. La mejora en las tecnicas para obtener soluciones factibles y de calidad esta permitiendo aplicar resultados teoricos en la resolucion de escenarios reales. En este estudio, se presenta la resolucion de un problema de enrutamiento de vehiculos con una flota heterogene...
Dec 5, 2010 in WSC (Winter Simulation Conference)
#1Angel A. Juan (UPC: Polytechnic University of Catalonia)H-Index: 25
#2Rubén Ruiz García (Polytechnic University of Valencia)H-Index: 38
Last.Dragos Ionescu (Open University of Catalonia)H-Index: 1
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A simulation-based algorithm for the Permutation Flowshop Sequencing Problem (PFSP) is presented. The algorithm uses Monte Carlo Simulation and a discrete version of the triangular distribution to incorporate a randomness criterion in the classical Nawaz, Enscore, and Ham (NEH) heuristic and starts an iterative process in order to obtain a set of alternative solutions to the PFSP. Thus, a random but biased local search of the space of solutions is performed, and a list of "good alternative solut...
3 Citations
Recently hybrid metaheuristics have been design to find solutions for combinatorial optimisation problems. We focus on hybrid procedures that combine local search based metaheuristics with exact algorithms of the operations research field. We present a mapping that outlines the metaheuristic and exact procedures used, the way they are related and the problems they have been applied to.
#1Helena Ramalhinho-Lourenço (UPF: Pompeu Fabra University)H-Index: 17
#2Olivier Martin (University of Paris-Sud)H-Index: 36
Last.Thomas Sttzle (ULB: Université libre de Bruxelles)H-Index: 61
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The key idea underlying iterated local search is to focus the search not on the full space of all candidate solutions but on the solutions that are returned by some underlying algorithm, typically a local search heuristic. The resulting search behavior can be characterized as iteratively building a chain of solutions of this embedded algorithm. The result is also a conceptually simple metaheuristic that nevertheless has led to state-of-the-art algorithms for many computationally hard problems. I...
278 CitationsSource