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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Distribui??o de derivados de petr?leo por redes de polidutos: uma abordagem atrav?s de algoritmos evolucion?rios h?bridos para um problema triobjetivo / Oil derivatives distribution on polyduct networks: a hybrid evolutionary algorithms approach for a tri-objective problem

Souza, Thatiana Cunha Navarro de 13 March 2015 (has links)
Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2016-04-08T22:40:13Z No. of bitstreams: 1 ThatianaCunhaNavarroDeSouza_TESE.pdf: 4253732 bytes, checksum: b88b33669e4903291d2e3da03d76f832 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2016-04-11T22:01:06Z (GMT) No. of bitstreams: 1 ThatianaCunhaNavarroDeSouza_TESE.pdf: 4253732 bytes, checksum: b88b33669e4903291d2e3da03d76f832 (MD5) / Made available in DSpace on 2016-04-11T22:01:06Z (GMT). No. of bitstreams: 1 ThatianaCunhaNavarroDeSouza_TESE.pdf: 4253732 bytes, checksum: b88b33669e4903291d2e3da03d76f832 (MD5) Previous issue date: 2015-03-13 / Um importante problema enfrentado pela ind?stria petrol?fera ? distribuir v?rios produtos derivados de petr?leo atrav?s de polidutos. Tal distribui??o ? feita atrav?s de uma rede composta por refinarias (n?s fonte), parques de armazenagem (n?s intermedi?rios) e terminais (n?s de demanda), interligados por um conjunto de polidutos que transportam petr?leo e derivados entre ?reas adjacentes. Restri??es relativas a limites de armazenamento, tempo de entrega, disponibilidade das fontes, limites de envio e recebimento, entre outras, t?m de ser satisfeitas. Alguns pesquisadores lidam com este problema sob o ponto de vista discreto onde o fluxo na rede ? visto como o envio de bateladas. Geralmente, n?o existem dispositivos de separa??o entre bateladas de produtos diferentes e as perdas devidas ? interface podem ser significativas. Minimizar o tempo de entrega ? um objetivo usual dos engenheiros durante a programa??o do envio de produtos em redes de polidutos. No entanto, os custos devidos ?s perdas geradas nas interfaces n?o podem ser desconsiderados. O custo do envio dos produtos tamb?m depende das despesas de bombeamento as quais s?o, em grande parte, devidas ao custo da energia el?trica. Uma vez que a tarifa industrial de energia el?trica varia ao longo do dia, o bombeamento em diferentes per?odos ter?o diferentes custos. Este trabalho apresenta uma investiga??o experimental de m?todos computacionais desenvolvidos para lidar com o problema do envio de bateladas de derivados de petr?leo considerando a minimiza??o simult?nea de tr?s fun??es objetivo: tempo de entrega, perdas devidas ?s interfaces e custo de energia el?trica. Tal problema ? NP- ?rduo e ser? abordado atrav?s de algoritmos evolucion?rios h?bridos. As hibridiza??es t?m como foco principal os Algoritmos Transgen?ticos e arquiteturas cl?ssicas de algoritmos evolucion?rios multi-objetivo como MOEA/D, NSGA2 e SPEA2. Tr?s arquiteturas denominadas MOTA/D, NSTA e SPETA, s?o aplicadas ao problema. ? apresentado um estudo experimental dos algoritmos propostos onde ? utilizado um conjunto de trinta casos teste. Para analisar os resultados obtidos com os algoritmos s?o empregados indicadores de qualidade Pareto concordantes e testes estat?sticos n?o param?tricos. / An important problem faced by the oil industry is to distribute multiple oil products through pipelines. Distribution is done in a network composed of refineries (source nodes), storage parks (intermediate nodes), and terminals (demand nodes) interconnected by a set of pipelines transporting oil and derivatives between adjacent areas. Constraints related to storage limits, delivery time, sources availability, sending and receiving limits, among others, must be satisfied. Some researchers deal with this problem under a discrete viewpoint in which the flow in the network is seen as batches sending. Usually, there is no separation device between batches of different products and the losses due to interfaces may be significant. Minimizing delivery time is a typical objective adopted by engineers when scheduling products sending in pipeline networks. However, costs incurred due to losses in interfaces cannot be disregarded. The cost also depends on pumping expenses, which are mostly due to the electricity cost. Since industrial electricity tariff varies over the day, pumping at different time periods have different cost. This work presents an experimental investigation of computational methods designed to deal with the problem of distributing oil derivatives in networks considering three minimization objectives simultaneously: delivery time, losses due to interfaces and electricity cost. The problem is NP-hard and is addressed with hybrid evolutionary algorithms. Hybridizations are mainly focused on Transgenetic Algorithms and classical multi-objective evolutionary algorithm architectures such as MOEA/D, NSGA2 and SPEA2. Three architectures named MOTA/D, NSTA and SPETA are applied to the problem. An experimental study compares the algorithms on thirty test cases. To analyse the results obtained with the algorithms Pareto-compliant quality indicators are used and the significance of the results evaluated with non-parametric statistical tests.
2

Algoritomos transgen?ticos aplicados ao problema da ?rvore geradora biobjetivo

Monteiro, Silvia Maria Diniz 17 February 2011 (has links)
Made available in DSpace on 2014-12-17T15:47:55Z (GMT). No. of bitstreams: 1 SilviaMDM_DISSERT.pdf: 1535044 bytes, checksum: 925f2f885f42335d55c35aa64bb4d026 (MD5) Previous issue date: 2011-02-17 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / The Multiobjective Spanning Tree is a NP-hard Combinatorial Optimization problem whose application arises in several areas, especially networks design. In this work, we propose a solution to the biobjective version of the problem through a Transgenetic Algorithm named ATIS-NP. The Computational Transgenetic is a metaheuristic technique from Evolutionary Computation whose inspiration relies in the conception of cooperation (and not competition) as the factor of main influence to evolution. The algorithm outlined is the evolution of a work that has already yielded two other transgenetic algorithms. In this sense, the algorithms previously developed are also presented. This research also comprises an experimental analysis with the aim of obtaining information related to the performance of ATIS-NP when compared to other approaches. Thus, ATIS-NP is compared to the algorithms previously implemented and to other transgenetic already presented for the problem under consideration. The computational experiments also address the comparison to two recent approaches from literature that present good results, a GRASP and a genetic algorithms. The efficiency of the method described is evaluated with basis in metrics of solution quality and computational time spent. Considering the problem is within the context of Multiobjective Optimization, quality indicators are adopted to infer the criteria of solution quality. Statistical tests evaluate the significance of results obtained from computational experiments / A ?rvore Geradora Multiobjetivo ? um problema de Otimiza??o Combinat?ria NP-?rduo. Esse problema possui aplica??o em diversas ?reas, em especial, no projeto de redes. Nesse trabalho, prop?e-se uma solu??o para o problema em sua vers?o biobjetivo por meio de um Algoritmo Transgen?tico, denominado ATIS-NP. A Transgen?tica Computacional ? uma t?cnica metaheur?stica da Computa??o Evolucion?ria cuja inspira??o est? na coopera??o (e n?o na competi??o) como fator de maior influ?ncia para a evolu??o. O algoritmo proposto ? a evolu??o de um trabalho que j? originou dois outros algoritmos transgen?ticos. Nesse sentido, os algoritmos previamente desenvolvidos tamb?m s?o apresentados. Essa pesquisa compreende ainda uma an?lise experimental que visa obter informa??es quanto ao desempenho do ATIS-NP quando comparado a outros algoritmos. Para tanto, o ATIS-NP ? comparado aos dois algoritmos anteriormente implementados, bem como a outro transgen?tico proposto na literatura para o problema tratado. Os experimentos computacionais abrangem ainda a compara??o do algoritmo desenvolvido a duas abordagens recentes da literatura que obt?m excelentes resultados, um GRASP e um gen?tico. A efici?ncia do m?todo apresentado ? avaliada com base em medidas de qualidade de solu??o e tempo computacional despendido. Uma vez que o problema se insere no contexto da Otimiza??o Multiobjetivo, indicadores de qualidade s?o utilizados para inferir o crit?rio de qualidade de solu??es obtidas. Testes estat?sticos avaliam a signific?ncia dos resultados obtidos nos experimentos computacionais

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