847 resultados para Logic-based optimization algorithm


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This paper deals with approaches for sparse matrix substitutions using vector processing. Many publications have used the W-matrix method to solve the forward/backward substitutions on vector computer. Recently a different approach has been presented using dependency-based substitution algorithm (DBSA). In this paper the focus is on new algorithms able to explore the sparsity of the vectors. The efficiency is tested using linear systems from power systems with 118, 320, 725 and 1729 buses. The tests were performed on a CRAY Y MP2E/232. The speedups for a fast-forward/fast-backward using a 1729-bus system are near 19 and 14 for real and complex arithmetic operations, respectively. When forward/backward is employed the speedups are about 8 and 6 to perform the same simulations.

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This study analyzes the perceptions of technical and administrative UFPA, in relation to the insertion of the components and assumptions of DBP in evaluation practice. Addresses the history, concepts, meanings, about AD methods, skills, evaluation skills, the APF and AD UFPA and Programme itself. The research is characterized as a hypothetical-deductive, descriptive and applied, using the case study. Data were analyzed using a quantitative approach, using the descriptive and inferential statistics. Data were collected through the application of questionnaires to 222 technical and administrative searched IFES, not occupants of FG and CD. The results indicate that the factors perceived in relation to the constituent elements such as: evaluation practice, measurement of competence, program management, timing, individual skills and fundamentals of the program and those related to assumptions such as: democratic process, integrative perspective, character development and pedagogical continuous evaluation practices are perceived in the evaluation process. The study concludes that comparing the results of the constituent elements and assumptions of the PAD of thechnical-administrative UFPA, it can be said about a tendency to change, though subtle, compared to the traditional model of AD, directed only to the granting of career progression for a new logic based on the results, showing an early effectiveness of the program evaluation practice by law and by the Institution. The results are confirmatory of advance evaluation practice in the institution, more so than has previously been expected, which demonstrates the value of scientific criteria of scientific research

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This article introduces an efficient method to generate structural models for medium-sized silicon clusters. Geometrical information obtained from previous investigations of small clusters is initially sorted and then introduced into our predictor algorithm in order to generate structural models for large clusters. The method predicts geometries whose binding energies are close (95%) to the corresponding value for the ground-state with very low computational cost. These predictions can be used as a very good initial guess for any global optimization algorithm. As a test case, information from clusters up to 14 atoms was used to predict good models for silicon clusters up to 20 atoms. We believe that the new algorithm may enhance the performance of most optimization methods whenever some previous information is available. (C) 2003 Wiley Periodicals, Inc.

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One common problem in all basic techniques of knowledge representation is the handling of the trade-off between precision of inferences and resource constraints, such as time and memory. Michalski and Winston (1986) suggested the Censored Production Rule (CPR) as an underlying representation and computational mechanism to enable logic based systems to exhibit variable precision in which certainty varies while specificity stays constant. As an extension of CPR, the Hierarchical Censored Production Rules (HCPRs) system of knowledge representation, proposed by Bharadwaj & Jain (1992), exhibits both variable certainty as well as variable specificity and offers mechanisms for handling the trade-off between the two. An HCPR has the form: Decision If(preconditions) Unless(censor) Generality(general_information) Specificity(specific_information). As an attempt towards evolving a generalized knowledge representation, an Extended Hierarchical Censored Production Rules (EHCPRs) system is suggested in this paper. With the inclusion of new operators, an Extended Hierarchical Censored Production Rule (EHCPR) takes the general form: Concept If (Preconditions) Unless (Exceptions) Generality (General-Concept) Specificity (Specific Concepts) Has_part (default: structural-parts) Has_property (default:characteristic-properties) Has_instance (instances). How semantic networks and frames are represented in terms of an EHCPRs is shown. Multiple inheritance, inheritance with and without cancellation, recognition with partial match, and a few default logic problems are shown to be tackled efficiently in the proposed system.

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Image categorization by means of bag of visual words has received increasing attention by the image processing and vision communities in the last years. In these approaches, each image is represented by invariant points of interest which are mapped to a Hilbert Space representing a visual dictionary which aims at comprising the most discriminative features in a set of images. Notwithstanding, the main problem of such approaches is to find a compact and representative dictionary. Finding such representative dictionary automatically with no user intervention is an even more difficult task. In this paper, we propose a method to automatically find such dictionary by employing a recent developed graph-based clustering algorithm called Optimum-Path Forest, which does not make any assumption about the visual dictionary's size and is more efficient and effective than the state-of-the-art techniques used for dictionary generation. © 2012 IEEE.

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Traditionally, ancillary services are supplied by large conventional generators. However, with the huge penetration of distributed generators (DGs) as a result of the growing interest in satisfying energy requirements, and considering the benefits that they can bring along to the electrical system and to the environment, it appears reasonable to assume that ancillary services could also be provided by DGs in an economical and efficient way. In this paper, a settlement procedure for a reactive power market for DGs in distribution systems is proposed. Attention is directed to wind turbines connected to the network through synchronous generators with permanent magnets and doubly-fed induction generators. The generation uncertainty of this kind of DG is reduced by running a multi-objective optimization algorithm in multiple probabilistic scenarios through the Monte Carlo method and by representing the active power generated by the DGs through Markov models. The objectives to be minimized are the payments of the distribution system operator to the DGs for reactive power, the curtailment of transactions committed in an active power market previously settled, the losses in the lines of the network, and a voltage profile index. The proposed methodology was tested using a modified IEEE 37-bus distribution test system. © 1969-2012 IEEE.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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A legislação ambiental cada vez mais rigorosa tem forçado as indústrias a investirem em soluções de controle inovadoras buscando diminuir as emissões de gases poluentes pelas fontes móveis e fixas, exercendo melhor controle e tratamento desses poluentes como forma de atender os limites impostos pela lei. Apresenta-se neste trabalho, a implementação de uma melhoria no sistema de controle de exaustão de fornos de cozimento de anodos da indústria de alumínio ALBRAS-Alumínio Brasileiro S.A., localizada em Barcarena no estado do Pará, visando minimizar a poluição causada pela queima de combustíveis nos fornos sem comprometer a eficiência do processo. Para isso foi utilizado um sistema baseado em lógica fuzzy, buscando na experiência de engenheiros, técnicos e operadores de processo, uma forma de se obter um melhor controle e confiabilidade na gestão das emissões de gases poluentes.

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O objetivo deste trabalho é a otimização da largura de banda de antenas linear e planar para aplicações em sistemas de banda larga. Nesse sentido, foi feito um estudo das técnicas de análise, aumento da largura de banda e otimização adequadas para o problema em questão. Como técnica de análise, foi utilizado o método dos momentos, o qual está apresentado no capítulo II. Para aumentar a largura de banda, foram utilizadas as técnicas de colocação de elementos parasitas e construção de fendas no radiador, descritos sucintamente no capítulo III. Como algoritmo de otimização, foi utilizado o algoritmo genético, descrito sucintamente no capítulo II. Neste trabalho, são apresentadas duas propostas de antenas, uma antena dipolo linear combinada com quatros espiras parasitas, capítulo IV, e uma antena planar do tipo espira, capítulo V. No primeiro caso, foram utilizados elementos parasitas e o algoritmo genético para aumentar a largura de banda e, no segundo, foram empregadas fendas no radiador e a otimização paramétrica para este objetivo.

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As estratégias de modernização da Amazônia concebidas pelo Estado nacional tinham em sua proposta as fragilizadas diretrizes geopolíticas de segurança e desenvolvimento regional, voltadas centralmente para a instalação de empreendimentos industriais, dentre elas as indústrias siderúrgicas independentes, sob a noção de que desta atividade passaria para a produção produtos de aço e assim se processaria o desenvolvimento regional. Pela análise das diferenciações das rotas de produção independente, integrada e semi-integrada é possível se compreender como os elementos das plantas industriais se comportam em cada rota e como se inter-relacionam com a socioeconomia regional. O trabalho de pesquisa junto à guseiras permitiu identificar que a instalação de siderúrgicas independentes nos municípios de Açailândia (MA) e Marabá (PA) gerou expectativas frustradas de desenvolvimento local, consolidando-se, portanto, apenas como atividade que possibilitou o crescimento econômico, pois manteve uma rota de produção que articulou a atividade com a socioeconomia regional em bases frágeis e insustentáveis, apoiada, sobretudo na demanda de carvão vegetal. As estruturas de custos e elementos estruturais de cada rota permitiram identificar as diferenças que cada rota apresenta, principalmente na relação mantida com a economia regional, por envolver novos processos, tecnologias e produtos diferenciados. A lógica produtiva das siderúrgicas independentes baseadas na transferência e externalização de custos para a sociedade, relações de trabalho limitadas e na degradação ambiental, sem, contudo, estabelecer processos de inovação, conduziu ao não estabelecimento de processos de desenvolvimento de base local. A perspectiva das rotas de produção siderúrgica integrada e semi-integrada que se instalam na Amazônia tem bases para alterar o cenário regionalmente desenhado e transformar as inter-relações mantidas pela siderurgia independente na Amazônia Oriental, pois articulam elementos que contribuem para a consolidação de efeitos de encadeamento para trás e para frente.

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Pós-graduação em Engenharia Elétrica - FEIS

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