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International audienceData grid applications require often an access to infrastructures with high performance data movement facilities coordinated with computational resources. Other applications need interconnections of large scale instruments with HPC platforms. In these context, dynamic provisioning of customized computing and networking infrastructure as well as resource virtualization are appealing technologies. Therefore new models and tools must be studied and developed to allow users create and handle such on-demand virtual infrastructures within grid platforms or even within the Internet. This work presents VXDL, a language for virtual resources interconnection networks specification and modeling. Besides allowing end resources description, VXDL lets users describe the desirable virtual network topology, including virtual routers and timeline. In this paper we motivate and present the key features of our modeling language. We explore typical examples to demonstrates the expressiveness and the pertinence of it. Then we detail experimental results based on the execution of NAS benchmark on virtual infrastructures, conforming different VXDL specifications

http://www.sciencedirect.com/science/article/pii/S1877050914006024International audienceData mining tools may be computationally demanding, so there is an increasing interest on parallel computing strategies to improve their performance. The popularization of Graphics Processing Units (GPUs) increased the computing power of current desktop computers, but desktop-based data mining tools do not usually take full advantage of these architectures. This paper exploits an approach to improve the performance of Weka, a popular data mining tool, through parallelization on GPU-accelerated machines. From the profiling of Weka object-oriented code, we chose to parallelize a matrix multiplication method using state-of-the-art tools. The implementation was merged into Weka so that we could analyze the impact of parallel execution on its performance. The results show a significant speedup on the target parallel architectures, compared to the original, sequential Weka code

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Este artigo relata uma experiência de exploração de resultados detalhados por questão, em provas do Enade de um curso de Bacharelado em Ciência da Computação, com o objetivo de reunir contribuições para a revisão de seu Projeto Pedagógico. A partir de relatórios do INEP para todas as cinco provas realizadas, obtiveram-se indicadores de possíveis fraquezas e forças do curso, analisando-se percentuais de acertos, conteúdos curriculares e enunciados das questões. Os dados estão disponibilizados online, podendo ser utilizados, com poucas substituições, por outras instituições avaliadas pelos mesmos exames.