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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

Um estudo algor?tmico de problemas log?sticos na ind?stria de petr?leo e g?s natural / An algorithmic study of logistic problems on petroleum and natural gas industry

Duarte, Herbert de Melo 16 November 2006 (has links)
Made available in DSpace on 2014-12-17T15:48:08Z (GMT). No. of bitstreams: 1 HerbertMD.pdf: 1096047 bytes, checksum: 6cf0c7d90914e2c3fd03f494b71cfa3a (MD5) Previous issue date: 2006-11-16 / This work consists on the study of two important problems arising from the operations of petroleum and natural gas industries. The first problem the pipe dimensioning problem on constrained gas distribution networks consists in finding the least cost combination of diameters from a discrete set of commercially available ones for the pipes of a given gas network, such that it respects minimum pressure requirements at each demand node and upstream pipe conditions. On its turn, the second problem the piston pump unit routing problem comes from the need of defining the piston pump unit routes for visiting a number of non-emergent wells in on-shore fields, i.e., wells which don t have enough pressure to make the oil emerge to surface. The periodic version of this problem takes into account the wells re-filling equation to provide a more accurate planning in the long term. Besides the mathematical formulation of both problems, an exact algorithm and a taboo search were developed for the solution of the first problem and a theoretical limit and a ProtoGene transgenetic algorithm were developed for the solution of the second problem. The main concepts of the metaheuristics are presented along with the details of their application to the cited problems. The obtained results for both applications are promising when compared to theoretical limits and alternate solutions, either relative to the quality of the solutions or to associated running time / Este trabalho consiste do estudo de dois importantes problemas oriundos das opera??es das ind?strias de petr?leo e g?s natural. O primeiro problema do dimensionamento de dutos em uma rede urbana de distribui??o de g?s natural consiste em encontrar a combina??o de di?metros de menor custo, a partir de um conjunto de op??es comercialmente dispon?veis, para os dutos de uma dada rede de distribui??o de g?s, de forma a respeitar requisitos de press?o m?nima em cada n? de demanda e condi??es de upstream. Por sua vez, o segundo problema do roteamento da unidade m?vel do pistoneio decorre da necessidade de se definir as rotas de visita??o da dita unidade m?vel do pistoneio aos diversos po?os n?o surgentes do campo de explora??o, ou seja, po?os que n?o possuem press?o suficiente para fazer o ?leo emergir ? superf?cie. A vers?o peri?dica do problema leva em considera??o a equa??o de re-enchimento dos po?os, de forma a possibilitar um planejamento mais acurado num horizonte de tempo maior. Al?m da formula??o matem?tica dos dois problemas, para a solu??o do primeiro foram desenvolvidos um algoritmo exato e uma busca tabu e para o segundo, um limite superior e um algoritmo transgen?tico ProtoGene. Os principais conceitos das metaheur?sticas s?o apresentados, juntamente com os detalhes da aplica??o destas aos problemas citados. Os resultados obtidos para ambas as aplica??es s?o promissores quando comparados com limites te?ricos e solu??es alternativas, tanto relativamente ? qualidade das solu??es como ao tempo computacional envolvido
2

Metaheur?sticas evolutivas para o problema de roteamento de unidades m?veis de pistoneio / Evolutionary metaheuristics applied to routing problem of units mobile recovery of oil

Nascimento, Jo?o Paulo Lima do 23 December 2010 (has links)
Made available in DSpace on 2014-12-17T14:53:02Z (GMT). No. of bitstreams: 1 JoaoPLN_DISSERT.pdf: 2086259 bytes, checksum: 2a57554e118e00d9a44cdf572e29af7a (MD5) Previous issue date: 2010-12-23 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / This paper presents metaheuristic strategies based on the framework of evolutionary algorithms (Genetic and Memetic) with the addition of Technical Vocabulary Building for solving the Problem of Optimizing the Use of Multiple Mobile Units Recovery of Oil (MRO units). Because it is an NP-hard problem, a mathematical model is formulated for the problem, allowing the construction of test instances that are used to validate the evolutionary metaheuristics developed / O presente trabalho apresenta estrat?gias metaheur?sticas baseadas no framework dos Algoritmos Evolutivos (Gen?ticos e Mem?ticos) com a adi??o da t?cnica Vocabulary Building para a resolu??o do Problema de Otimiza??o do Emprego de Unidades M?veis de Pistoneio (UMPs). Por se tratar de um problema NP-?rduo, uma modelagem matem?tica ? formulada para o problema, permitindo a constru??o de inst?ncias testes que s?o utilizadas para validar as metaheur?sticas evolutivas desenvolvidas

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