AgradecimientosComo es de esperarse este trabajo sería imposible de realizar completamente solo, y por lo tanto quisiera expresar mi gratitud a todos aquellos que han sido participes de este. En primer lugar, quisiera agradecer a mis directores de tesis, Vicente y Vicent, por su permanente colaboración, motivación y entusiasmo que no solo mejoraron la calidad de este trabajo sino que me transmitieron el interés permanente por la investigación, y a Jorge, cuya aportación ha sido fundamental para la realización de este trabajo. También al grupo GIRBA, que ha apoyado esta investigación.Por otro lado, quiero agradecer a aquellos con los que compartí a diario durante la realización de esta tesis: Elena, Maria José, Salva, David, Julián.Todos ellos de alguna manera han contribuido a este trabajo, y han sido una fuente de aliento durante este tiempo.Asimismo quiero agradecer el apoyo y guía prestados por el Prof. Ian Akyildiz durante mi estancia realizada en el BWN lab. También a los miembros del BWN Lab por su cordialidad y colaboración.Finalmente, quiero agradecer a mi familia por su generosidad, apoyo permanente y también paciencia. Este trabajo sería impensable sin ellos. AbstractPerformance requirements on mobile networks are tighter than ever as a result of the adoption of mobile devices such as smartphones or tablets, and the QoS levels that mobile applications demand for their correct operation.The data traffic volume carried in mobile networks for 2012 is the same as the total internet traffic in 2000, and this exponential growth tendency will continue in years to come. In order to fulfill users' expectations, it is imperative for mobile networks to make the best use of the available resources.Heterogeneous networks (Hetnets) have the ability to integrate several technologies in a coherent and efficient manner in order to enhance users' experience. The first challenge of heterogeneous networks is to integrate several radio access technologies, which exist as a result of simultaneous technology developments and a paced replacement of legacy technology. A joint management of several RAT's enhances network's efficiency, and this influences user's experience. Another challenge of heterogeneous networks is the improvement of current macrocells through an efficient use of the electromagnetic spectrum. Some approaches aim to optimize the antennas or use higher-order modulation techniques, but a more disruptive approach is the use of dynamic spectrum techniques through a technology known as cognitive radio. Finally, heterogeneous networks should be able to integrate several layers. In addition to the well studied micro and pico cells, a new generation of cheaper and easily configurable small cell networks have been proposed. However, its success is attached to its ability to adapt to the current context of mobile networks.ix This thesis aims to analyze three different aspects of heterogeneous networks from a resource management and access control point of view. In the first part, a joint call admission control proble...

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estudo de casos para comparar os resultados obtidos com o programa implementado.Um objetivo adicional deste trabalho é expor à comunidade naval a utilidade e efetividade dos algoritmos genéticos nos problemas de projeto multiobjetivo. O enfoque desta pesquisa está na metodologia implementada e na sua recomendação para o projeto preliminar de navios. Palavras chaves: Algoritmos Genéticos. Navio Tanque (Projeto). OtimizaçãoMatemática. ABSTRACTThis paper shows the rational process of selecting the optimal dimensions and forms coefficients of tanker ships using the technique of genetic algorithm. It is proposed a procedure to balance designs in weight and useful space and assesses their feasibility so that weight and volume limited tankers can be balanced. The elaboration of a procedure and its implementation in an efficient program is so important in the preliminary dimension of a ship, so this paper is a divulgation of the genetic algorithm as robust technique for the preliminary ship design. Two objective attributes are used to evaluate each design: Total Cost and Mean Oil Outflow. This attributes are conflicting between them, that is, a low cost correspond a high outflow and vice versa. The Mean Oil Outflow is evaluated with the probabilistic methodology proposed by the INTERTANKO to IMO. The assessment of mean oil outflow, by a non dimensional parameter, supposes the event of grounding and/or collision resulting in bottom and side damage respectively. In estimating the cost two models are used performing a comparison of their effects on the final values of principal dimension. In addition, for the balance procedure, five hull weight models are tested and analyzed the impact on the form and distribution of Pareto frontier.A genetic algorithm is implemented to search the optimal design parameters and identify non-dominated frontier of Pareto. The algorithm is tested with four test functions found in the technical literature. The test functions selected are convex, non convex, discontinuing and one with four restrictions. The implementation shows similar results with those showed in others papers. A Suezmax, an Aframax, and a Panamax ships are used as case study in order to compare the gotten results by the implemented program.One additional goal of this work is to expose to naval community the usefulness and effectiveness of the genetic algorithm in the Multi-Objective design. The emphasis of this paper is on methodology of design implemented and is suggested for preliminary ship design.

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