DECEA - Departamento de Ciências Exatas e Aplicadas

URI permanente desta comunidadehttp://www.hml.repositorio.ufop.br/handle/123456789/551

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20122

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Autor: search.filters.author.Martins, Alexandre XavierAssunto: search.filters.subject.Variable neighborhood descent

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Agora exibindo 1 - 2 de 2
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    Genils-TS-CL-PR : um algoritmo heurístico para resolução do problema de roteamento de veículos com coleta e entrega simultânea.
    (2012) Silva, Thaís Cotta Barbosa da; Cruz, Raphael Carlos; Souza, Marcone Jamilson Freitas; Martins, Alexandre Xavier; Coelho, Vitor Nazário; Mine, Marcio Tadayuki
    This work addresses the Vehicle Routing Problem with Simultaneous Pickup and Delivery (VRPSPD). We propose the algorithm GENILS-TS-CL-PR for solving it. This algorithm combines the heuristic procedures Cheapest In- sertion, Cheapest Insertion with multiple routes, GENIUS, Iterated Local Search (ILS), Variable Neighborhood Descent (VND), Tabu Search (TS) and Path Relin king (PR). The first three procedures aim to obtain a good initial solution, and the VND and TS are used as local search methods for ILS. TS is applied after some iterations without any improvement through of the VND. The PR procedure is performed for each ILS iteration and it connects a local optimum with an elite solution generated during the search. The algorithm also uses a strategy to re- duce the number of solutions evaluated in the solution space. It was tested on benchmark instances taken from the literature and it was able to generate high quality solutions.
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    Variable neighborhood descent with iterated local search for routing and wavelength assignment.
    (2012) Martins, Alexandre Xavier; Duhamel, Christophe; Mahey, Philippe; Saldanha, Rodney Rezende; Souza, Maurício Cardoso de
    In this work we treat the Routing and Wavelength Assignment (RWA) with focus on minimizing the number of wavelengths to route demand requests. Lightpaths are used to carry the traffic optically between origin-destination pairs. The RWA is subjected to wavelength continuity constraints, and a particular wavelength cannot be assigned to two different lightpaths sharing a common physical link. We develop a Variable Neighborhood Descent (VND) with Iterated Local Search (ILS) for the problem. In a VND phase we try to rearrange requests between subgraphs associated to subsets of a partition of the set of lightpath requests. In a feasible solution, lightpaths belonging to a subset can be routed with the same wavelength. Thus, the purpose is to eliminate one subset of the partition. When VND fails, we perform a ILS phase to disturb the requests distribution among the subsets of the partition. An iteration of the algorithm alternates between a VND phase and a ILS phase. We report computational experiments that show VND-ILS was able to improve results upon powerful methods proposed in the literature.