A number of parallel gradient-free local optimization methods are investigated in application to problems of voyage planning for maritime ships. Two optimization algorithms are investigated, a parallel version of the Nelder-Mead Simplex method and the Subplex method with Nelder-Mead Simplex as its inner solver. Additionally, two new formulations of the optimization problem are suggested which together with an improved implementation of the objective function increases the overall performance of the model. Numerical results show the efficiency of these methods in comparison with the earlier introduced Grid search method and solvers from an open-source optimization library.

Ce mémoire présente les travaux réalisés en aérodynamique afin de pouvoir disposer d’une chaîne de conception complète nécessaire au traitement des différentes problématiques sur les pales éoliennes, qui ne peuvent être pris en compte à l’aide d’une méthode unique. Afin de pouvoir faire de l’optimisation de pales en fonction de différents critères, un outil numérique simplifié (VALDAG) a été développé. Le module de simulation utilise la méthode du Disque Actif Généralisé, qui s’appuie sur la résolution des équations Navier-Stokes, complété par des corrections empiriques. Il respecte un compromis entre la précision et le coût de calcul. Cet outil pour lequel une interface web a été développée pour le rendre adapté à des travaux d’ingénierie est susceptible de se calibrer automatiquement sur une nouvelle géométrie de pale grâce à la méthode Nelder-Mead Simplex. On peut ensuite réaliser une optimisation de la performance de la pale en modifiant cette géométrie, et générer les fichiers 3D qui serviront d’entrée à la simulation 3D et de visualisation des optimisations de forme. Ces designs optimisés sont ensuite validés par des simulations DNS à l’aide de l’outil NaSCar 3D développé à l’INRIA. Cet outil résout des équations Navier-Stokes sur un maillage cartésien 3D et prend en compte des obstacles immergés via la fonction Level-Set et la pénalisation. Après des adaptations sur le traitement de la géométrie de pales, un compromis de configuration CFD est trouvé pour simuler un rotor éolien. En conclusion, ce paquet d’outils VALDAG est peu coûteux, facile à utiliser et efficace. En associant VALDAG aux simulations 3D, une chaîne de conception est complétée. / This Ph.D. thesis presents some research work on aerodynamics of wind turbine blades, in order to dispose a conception chain necessary for different problems, which cannot be treated by one unique method. A simplified numerical toolkit (VALDAG) has been developed to optimize the performance of blades in different creteria. The simulation module use the Generalized Actuator Disc model, which relies on the solution of Navier-Stokes equations and completed with empiric corrections. This tool respects a reasonable compromise between model complexity and computational reliability. An automatic calibration mechanism was implemented using the Nelder-Mead Simplex algorithm. A web users interface (WUI) is also available to adapt VALDAG for industrial engineers. Optimization is then carried on by modifying the blades’ geometry parameters and the designs optimized is stocked in files which can be used for 3D simulation and/or visualization. The blade designed with VALDAG are then simulated by a 3D numerical tool to validate previous predictions. This 3D tool called NaSCar 3D is developed in INRIA and resolve Navier-Stokes equations on to a cartesian mesh, in which the immersed obstacles are considered with the Level-Set function and the penalization method. After some necessary adaptation for the treatment of blades’ geometry, a compromise on CFD configuration is found to simulate a wind turbine rotor. To conclude, this design toolkit VALDAG is low time-costly, user-friendly and efficient. Associated with 3D simulations, a conception chain has been established.

Made available in DSpace on 2014-07-29T15:08:22Z (GMT). No. of bitstreams: 1 Adson.pdf: 1251737 bytes, checksum: 08b3122009f15a40cec4f32fda3231e9 (MD5) Previous issue date: 2008-11-07 / The present work deals with the problem of planning the distribution system of electricity and is divided into three parts: Problem Definition, Resolution Approaches and Results and Conclusions. The energy distribution networks are of great economic importance in countries like Brazil. On one hand, there are fixed costs of physical installation and operation of the network, mainly due to the costs of energy losses and, secondly, the natural obstacles along the possible passages of network s links. The large amount of these costs, together with lack of efficient methods when it comes to real applications in the matter, justify the development of this research. The study of such aspects, the precise definition of the problem and the reasons that motivated this work can be found on the first part of this work. The second part shows the approaches for resolution. Three proposals methods were adopted: the first uses the algorithm Prim associated with the method Nelder-Mead Simplex. In the second proposal uses Dynamic Programming and, finally, we take the metaphor of Ant Colony also associated with the Nelder-Mead Simplex. The results, presented at the third part of this work, demonstrated the effectiveness of the proposed methods, especially the good compromise between performance and applicability obtained by the third proposal. / O presente trabalho lida com o problema de planejamento da rede de distribuição de energia elétrica, estando dividido em três partes: Definição do Problema, Abordagens de Resolução e Resultados e Conclusões. As redes de distribuição de energia têm uma grande importância econômica em países como o Brasil. Por um lado, há os custos físicos fixos de instalação e de operação da rede, sobretudo os custos devido às perdas de energia e, por outro, os obstáculos naturais impostos ao longo das possíveis passagens para as ligações da rede. O montante elevado destes custos, unidos à escassez de métodos eficientes quando se trata de aplicações reais no assunto, justificam o desenvolvimento desta pesquisa. O estudo de tais aspectos, a definição precisa do problema e as justificativas podem ser encontradas na primeira parte deste trabalho. Na segunda parte, apresentam-se as abordagens de resolução. Três propostas foram adotadas: na primeira usa-se o algoritmo Prim associado ao método Nelder-Mead Simplex. Na segunda proposta utiliza-se a Programação Dinâmica e, por fim, tomamos a metáfora de colônia de formigas também associada ao Nelder-Mead Simplex. Os resultados, apresentados na terceira parte deste trabalho, mostram a eficácia dos métodos propostos, em especial o bom compromisso entre performance e aplicabilidade obtido pela terceira proposta.

Forests have been proposed as a means of reducing atmospheric carbon dioxide levels due to their ability to store carbon as biomass. To quantify the amount of atmospheric carbon sequestered by forests, biomass and density estimates are often needed. This study develops, implements, and tests an individual tree-based algorithm for obtaining forest density and biomass using orthophotographs and small footprint LiDAR imagery. It was designed to work with a range of forests and image types without modification, which is accomplished by using generic properties of trees found in many types of images. Multiple parameters are employed to determine how these generic properties are used. To set these parameters, training data is used in conjunction with an optimization algorithm (a modified Nelder-Mead simplex algorithm or a genetic algorithm). The training data consist of small images in which density and biomass are known. A first test of this technique was performed using 25 circular plots (radius = 15 m) placed in young pine plantations in central Virginia, together with false color othophotograph (spatial resolution = 0.5 m) or small footprint LiDAR (interpolated to 0.5 m) imagery. The highest density prediction accuracies (r2 up to 0.88, RMSE as low as 83 trees / ha) were found for runs where photointerpreted densities were used for training and testing. For tests run using density measurements made on the ground, accuracies were consistency higher for orthophotograph-based results than for LiDAR-based results, and were higher for trees with DBH ≥10cm than for trees with DBH ≥7 cm. Biomass estimates obtained by the algorithm using LiDAR imagery had a lower RMSE (as low as 15.6 t / ha) than most comparable studies. The correlations between the actual and predicted values (r2 up to 0.64) were lower than comparable studies, but were generally highly significant (p ≤ 0.05 or 0.01). In all runs there was no obvious relationship between accuracy and the amount of training data used, but the algorithm was sensitive to which training and testing data were selected. Methods were evaluated for combining predictions made using different parameter sets obtained after training using identical data. It was found that averaging the predictions produced improved results. After training using density estimates from the human photointerpreter, 89% of the trees located by the algorithm corresponded to trees found by the human photointerpreter. A comparison of the two optimization techniques found them to be comparable in speed and effectiveness. / Ph. D.

Submitted by FABRÍCIO MACIEL GOMES null (fabricio@dequi.eel.usp.br) on 2016-01-04T00:06:19Z No. of bitstreams: 1 Tese_Fabricio_Maciel_Gomes.pdf: 1836829 bytes, checksum: 3ec7860a9d87ebfeaef21b25dc157d25 (MD5) / Approved for entry into archive by Juliano Benedito Ferreira (julianoferreira@reitoria.unesp.br) on 2016-01-06T16:12:19Z (GMT) No. of bitstreams: 1 gomes_fm_dr_guara.pdf: 1836829 bytes, checksum: 3ec7860a9d87ebfeaef21b25dc157d25 (MD5) / Made available in DSpace on 2016-01-06T16:12:19Z (GMT). No. of bitstreams: 1 gomes_fm_dr_guara.pdf: 1836829 bytes, checksum: 3ec7860a9d87ebfeaef21b25dc157d25 (MD5) Previous issue date: 2015-12-15 / Empresas não medem esforços para aperfeiçoar seus processos e produtos de acordo com diferentes critérios para satisfazer as exigências e necessidades dos clientes em busca de um padrão de competitividade superior ao de suas concorrentes. Neste cenário é muito comum a necessidade de se estabelecer condições que resultem na melhoria de mais de um critério de forma simultânea. Neste trabalho foi realizada uma avaliação da utilização de quatro métodos que utilizam as Meta-heurísticas Recozimento Simulado, Algoritmo Genético, Recozimento Simulado combinado com o método Nelder Mead Simplex e algoritmo genético combinado com o método Nelde-Mead simplex para o estabelecimento de melhoria das condições de processos com múltiplas respostas. Para a avaliação dos métodos propostos foram utilizados problemas-teste criteriosamente selecionados na literatura de forma a serem analisados casos com diferente número de variáveis, número de respostas e tipos de resposta. A aglutinação das respostas foi realizada por quatro métodos diferentes: Desirability, Desvio Médio Percentual, Programação por Compromisso e Programação por Compromisso normalizada pela distância euclidiana. A avaliação dos métodos foi realizada por meio de comparação entre os resultados obtidos na utilização de um mesmo método de aglutinação, determinando assim a eficiência do método de busca. Os resultados obtidos na avaliação dos métodos sugerem a aplicação do método do algoritmo genético quando se pretende estabelecer parâmetros que resultem na melhoria de processos com múltiplas respostas, em particular quando essas respostas são modeladas por equações com termos cúbicos, independentemente do número de termos que possam conter, do tipo de respostas e do número de variáveis. / Companies go to great lengths to improve its processes and products according to different criteria to meet the demands and needs of customers looking for a higher standard of competitiveness to that of their competitors. This scenario is very common the need to establish conditions that result in the improvement of more than one criterion simultaneously. This work was carried out an evaluation of the use of four methods that use Metaheuristics Simulated Annealing, Genetic Algorithms, Simulated Annealing combined with the Nelder Mead Simplex method and genetic algorithm combined with Nelde Mead simplex method for the improvement of establishing the conditions of processes with multiple answers. For the evaluation of the proposed test methods were used in the literature problems carefully selected in order to be analyzed cases with different numbers of variables, response numbers and types of responses. In this research we used the average percentage deviation function as a way to bring together the answers. The agglutination of the answers was performed by four different methods: Desirability, Average Percentage Deviation, Compromise Programming and Compromise Programming normalized by Euclidean distance. The evaluation method was performed by comparison between the results obtained in using the same bonding method, thereby determining the efficiency of the search method. The results obtained in the evaluation of the methods suggest the application of the genetic algorithm method when you want to set parameters that result in the improvement of processes with multiple answers, particularly when these responses are modeled by equations with cubic terms, regardless of the number of terms that can contain the type of responses and the number of variables.