Uma implementação paralela híbrida para o problema do caixeiro viajante usando algoritmos genéticos, GRASP e aprendizagem por reforço

The metaheuristics techiniques are known to solve optimization problems classified as NP-complete and are successful in obtaining good quality solutions. They use non-deterministic approaches to generate solutions that are close to the optimal, without the guarantee of finding the global optimum. Motivated by the difficulties in the resolution of these problems, this work proposes the development of parallel hybrid methods using the reinforcement learning, the metaheuristics GRASP and Genetic Algorithms. With the use of these techniques, we aim to contribute to improved efficiency in obtaining efficient solutions. In this case, instead of using the Q-learning algorithm by reinforcement learning, just as a technique for generating the initial solutions of metaheuristics, we use it in a cooperative and competitive approach with the Genetic Algorithm and GRASP, in an parallel implementation. In this context, was possible to verify that the implementations in this study showed satisfactory results, in both strategies, that is, in cooperation and competition between them and the cooperation and competition between groups. In some instances were found the global optimum, in others theses implementations reach close to it. In this sense was an analyze of the performance for this proposed approach was done and it shows a good performance on the requeriments that prove the efficiency and speedup (gain in speed with the parallel processing) of the implementations performed

Otimização de modelos de predição da perda de propagação aplicáveis em 3,5GHZ utilizando algoritmos genéticos

The telecommunications industry has experienced recent changes, due to increasing quest for access to digital services for data, video and multimedia, especially using the mobile phone networks. Recently in Brazil, mobile operators are upgrading their networks to third generations systems (3G) providing to users broadband services such as video conferencing, Internet, digital TV and more. These new networks that provides mobility and high data rates has allowed the development of new market concepts. Currently the market is focused on the expansion of WiMAX technology, which is gaining increasingly the market for mobile voice and data. In Brazil, the commercial interest for this technology appears to the first award of licenses in the 3.5 GHz band. In February 2003 ANATEL held the 003/2002/SPV-ANATEL bidding, where it offered blocks of frequencies in the range of 3.5 GHz. The enterprises who purchased blocks of frequency were: Embratel, Brazil Telecom (Vant), Grupo Sinos, Neovia and WKVE, each one with operations spread in some regions of Brazil. For this and other wireless communications systems are implemented effectively, many efforts have been invested in attempts to developing simulation methods for coverage prediction that is close to reality as much as possible so that they may become believers and indispensable tools to design wireless communications systems. In this work wasm developed a genetic algorithm (GA's) that is able to optimize the models for predicting propagation loss at applicable frequency range of 3.5 GHz, thus enabling an estimate of the signal closer to reality to avoid significant errors in planning and implementation a system of wireless communication

Algoritmos genéticos aplicados a um comitê de LS-SVM em problemas de classificação

The pattern classification is one of the machine learning subareas that has the most outstanding. Among the various approaches to solve pattern classification problems, the Support Vector Machines (SVM) receive great emphasis, due to its ease of use and good generalization performance. The Least Squares formulation of SVM (LS-SVM) finds the solution by solving a set of linear equations instead of quadratic programming implemented in SVM. The LS-SVMs provide some free parameters that have to be correctly chosen to achieve satisfactory results in a given task. Despite the LS-SVMs having high performance, lots of tools have been developed to improve them, mainly the development of new classifying methods and the employment of ensembles, in other words, a combination of several classifiers. In this work, our proposal is to use an ensemble and a Genetic Algorithm (GA), search algorithm based on the evolution of species, to enhance the LSSVM classification. In the construction of this ensemble, we use a random selection of attributes of the original problem, which it splits the original problem into smaller ones where each classifier will act. So, we apply a genetic algorithm to find effective values of the LS-SVM parameters and also to find a weight vector, measuring the importance of each machine in the final classification. Finally, the final classification is obtained by a linear combination of the decision values of the LS-SVMs with the weight vector. We used several classification problems, taken as benchmarks to evaluate the performance of the algorithm and compared the results with other classifiers

Acelerando algoritmos de baixo nível em visão robótica com hardware reconfigurável

A challenge that remains in the robotics field is how to make a robot to react in real time to visual stimulus. Traditional computer vision algorithms used to overcome this problem are still very expensive taking too long when using common computer processors. Very simple algorithms like image filtering or even mathematical morphology operations may take too long. Researchers have implemented image processing algorithms in high parallelism hardware devices in order to cut down the time spent in the algorithms processing, with good results. By using hardware implemented image processing techniques and a platform oriented system that uses the Nios II Processor we propose an approach that uses the hardware processing and event based programming to simplify the vision based systems while at the same time accelerating some parts of the used algorithms

Desenvolvimento de um Sistema de Visão Global para uma Frota de Mini-Robôs Móveis

Navigation based on visual feedback for robots, working in a closed environment, can be obtained settling a camera in each robot (local vision system). However, this solution requests a camera and capacity of local processing for each robot. When possible, a global vision system is a cheapest solution for this problem. In this case, one or a little amount of cameras, covering all the workspace, can be shared by the entire team of robots, saving the cost of a great amount of cameras and the associated processing hardware needed in a local vision system. This work presents the implementation and experimental results of a global vision system for mobile mini-robots, using robot soccer as test platform. The proposed vision system consists of a camera, a frame grabber and a computer (PC) for image processing. The PC is responsible for the team motion control, based on the visual feedback, sending commands to the robots through a radio link. In order for the system to be able to unequivocally recognize each robot, each one has a label on its top, consisting of two colored circles. Image processing algorithms were developed for the eficient computation, in real time, of all objects position (robot and ball) and orientation (robot). A great problem found was to label the color, in real time, of each colored point of the image, in time-varying illumination conditions. To overcome this problem, an automatic camera calibration, based on clustering K-means algorithm, was implemented. This method guarantees that similar pixels will be clustered around a unique color class. The obtained experimental results shown that the position and orientation of each robot can be obtained with a precision of few millimeters. The updating of the position and orientation was attained in real time, analyzing 30 frames per second

Algoritmos evolutivos dedicados à reconfiguração de redes radiais de distribuição sob demandas fixas e variáveis: estudo dos operadores genéticos e parâmetros de controle

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Aprendizado significativo aplicado ao ensino de algoritmos

The course of Algorithms and Programming reveals as real obstacle for many students during the computer courses. The students not familiar with new ways of thinking required by the courses as well as not having certain skills required for this, encounter difficulties that sometimes result in the repetition and dropout. Faced with this problem, that survey on the problems experienced by students was conducted as a way to understand the problem and to guide solutions in trying to solve or assuage the difficulties experienced by students. In this paper a methodology to be applied in a classroom based on the concepts of Meaningful Learning of David Ausubel was described. In addition to this theory, a tool developed at UFRN, named Takkou, was used with the intent to better motivate students in algorithms classes and to exercise logical reasoning. Finally a comparative evaluation of the suggested methodology and traditional methodology was carried out, and results were discussed

Desenvolvimento e validação de técnica quantitativa de análise de imagem para avaliação do teste do cometa corado pela prata

INTRODUÇÃO: O ensaio do cometa ou técnica da eletroforese de células isoladas é largamente empregado para avaliação de danos e reparo do DNA em células individuais. O material pode ser corado por técnicas de fluorescência ou por sal de prata. Este último apresenta vantagens técnicas, como o tipo de microscópio utilizado e a possibilidade de armazenamento das lâminas. A análise dos cometas pode ser feita de modo visual, porém há a desvantagem da subjetividade dos resultados, que pode ser minimizada por análise digital automatizada. OBJETIVOS: Desenvolvimento e validação de método de análise digital de cometas corados por sal de prata. MÉTODOS: Cinquenta cometas foram fotografados de maneira padronizada e impressos em papel. Além de medidas manualmente, essas imagens foram classificadas em cinco categorias por três avaliadores, antes e depois de pré-processadas automaticamente pelo software ImageJ 1.38x. As estimativas geradas pelos avaliadores foram comparadas quanto sua correlação e reprodutibilidade. em seguida, foram desenvolvidos algoritmos de análise digital das medidas, com base em filtros estatísticos de mediana e de mínimo. Os valores obtidos foram comparados com os estimados manual e visualmente após o pré-processamento. RESULTADOS: As medidas manuais das imagens pré-processadas apresentaram maior correlação intraclasse do que as imagens preliminares. Os parâmetros automatizados apresentaram alta correlação com as medidas manuais pré-processadas, sugerindo que este sistema aumenta a objetividade da análise, podendo ser utilizado na estimativa dos parâmetros dos cometas. CONCLUSÃO: A presente análise digital proposta para o teste do cometa corado pela prata mostrou-se factível e de melhor reprodutibilidade que a análise visual.

Desenvolvimento e implementação de um sistema para detecção de falhas em estruturas usando microcontrolador

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Desenvolvimento de sistema de aquisição e processamento para aplicações em qualidade de energia

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Geração de algoritmos de escalonamento para simulação de grades computacionais

Pós-graduação em Ciência da Computação - IBILCE

Algoritmos de alinhamento múltiplo e técnicas de otimização para esses algoritmos utilizando Ant Colony

Pós-graduação em Ciência da Computação - IBILCE

Detecção de falhas estruturais usando sensores e atuadores piezelétricos e algoritmos genéticos

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Desenvolvimento e implementação de modelos para simulação de dados SNPs

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Desenvolvimento de um método numérico para simular escoamentos viscoelásticos axissimétricos com superfícies livres: Modelo PTT

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)