Alysson M. Costa

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This article describes and compares three heuristics for a variant of the Steiner tree problem with revenues, which includes budget and hop constraints. First, a greedy method which obtains good approximations in short computational times is proposed. This initial solution is then improved by means of a destroyand-repair method or a tabu search algorithm.(More)
The Steiner tree problem with revenues, budget and hop constraints is a variant of the Steiner tree problem where, besides the costs associated with arcs, there are also revenues associated with the vertices. Budget and hop constraints impose limits on the total cost of the network and on the number of edges between any vertex and the root, respectively.(More)
We propose simple heuristics for the assembly line worker assignment and balancing problem. This problem typically occurs in assembly lines in sheltered work centers for the disabled. Different from the classical simple assembly line balancing problem, the task execution times vary according to the assigned worker. We develop a constructive heuristic(More)
Three white-rot fungi (Pleurotus sajor caju, Trametes versicolor and Phanerochaete chrysosporium) and one soft-rot fungi (Rhizopus oryzae) species confirmed their potential for future applications in the biological treatment of effluents derived from the secondary treatment of a bleached kraft pulp mill processing Eucalyptus globulus. Among the four species(More)
Solving multicommodity capacitated network design problems is a hard task that requires the use of several strategies like relaxing some constraints and strengthening the model with valid inequalities. In this paper, we compare three sets of inequalities that have been widely used in this context: Benders, metric and cutset inequalities. We show that(More)
We face the problem of programming assembly lines when each task has a different completion time depending on the worker assigned to its execution. This problem appears in the context of sheltered work centers for the disabled, where the workers have disabilities that might impede or difficult the carrying out of some tasks. We develop a tabu search(More)
People with disabilities have a right to a full life in every sense and one of those fundamental rights is the possibility to work. In this paper the importance of social employment integration of disabled people is highlighted as one of the stakeholders to be satisfied by companies in the new framework that the Corporate Social Responsibility is(More)
This is a survey of the Steiner tree problem with profits, a variation of the classical Steiner problem where, besides the costs associated with edges, there are also revenues associated with vertices. The relationships between these costs and revenues are taken into consideration when deciding which vertices should be spanned by the solution tree. The(More)
Assembly lines are manufacturing systems in which a product is assembled progressively in workstations by different workers or machines, each executing a subset of the needed assembly operations (or tasks). We consider the case in which task execution times are worker-dependent and uncertain, being expressed as intervals of possible values. Our goal is to(More)