Primeiramente gostaria de agradecer aos meus pais Moacir e Sueli pela dedicação, amor, e por todos os conselhos e exemplos que zeram com que eu me tornasse uma pessoa melhor. À minha orientadora Maristela Oliveira dos Santos pela orientação, dedicação, paciência, amizade e pela conança depositada durante o decorrer deste trabalho. Aos amigos de laboratório sempre presentes e a disposição para o que fosse necessário, nos momentos de trabalho e de lazer. Ao Victor, Márcio e Tamara, por terem me recebido tão bem em São Carlos e por todos os conselhos e momentos felizes de happy hours e pós happy hours (posto). Aos meus amigos de Piratininga e arredores, pela amizade e por estarem presentes em minha vida. Um agradecimento especial aos meus grandes amigos de graduação Guilherme, Ígor e Wesley pelos conselhos e apoio nos momentos de incertezas. Aos membros das bancas de qualicação e de defesa por todas as sugestões e conselhos feitos para melhorar este trabalho. A todos os funcionários do ICMC que, direta ou indiretamente, contribuíram com este trabalho. Principalmente às funcionárias da secretaria da Pós-graduação por toda o auxílio oferecido para que este trabalho pudesse ser concluído. Ao CNPq pelo apoio nanceiro durante a execução deste trabalho.
This paper addresses the lot-sizing and scheduling problem of pulp and paper mills involving multiple paper machines. The underlying multi-stage integrated production process considers the following critical units: continuous digester, intermediate stocks of pulp and liquor, multiple paper machines and a recovery line to treat by-products. This work presents a mixed integer programming (MIP) model to represent the problem, as well as a solution approach based on a customized genetic algorithm (GA) with an embedded residual linear programming model. Some GA tools are explored, including literature and new operators, a novel diversification process and other features. In particular, the diversification process uses a new allele frequency measure to change between diversification and intensification procedures. Computational results show the effectiveness of the method to solve relatively large instances of the single paper machine problem when compared to other single paper machine solution methods found in the literature. For multiple paper machine settings, in most runs the GA solutions are better than those obtained for the MIP model using an optimization software.
The problem addressed in this paper focuses on the reduction of electrical energy costs for the operation of hydraulic pumps, which are used for catchment and distribution of water in water supply systems. As the electricity tariffs are different according to the time of day, it is necessary to decide when and how many pumps must be used to collect and distribute water, in each period of time, and, when there must be water transfer among tanks so that the demand of each consumer center is met without a lack of resources. A mixed integer programming (MIP) model is proposed and a competitive MIP‐based heuristic is developed to solve this problem. Numerical tests in a case study carried out with the water supply system of a Brazilian city demonstrate the efficiency of the proposed mathematical model and solution method.
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