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Item A new approach to constrained total least squares image restoration.(2000) Ng, Michael K.; Plemmons, Robert J.; Pimentel, Felipe RogérioRecently there has been a growing interest and progress in using total least squares (TLS) methods for solving blind deconvolution problems arising in image restoration. Here, the true image is to be estimated using only partial information about the blurring operator, or point spread function (PSF), which is subject to error and noise. In this paper, we present a new iterative, regularized, and constrained TLS image restoration algorithm. Neumann boundary conditions are used to reduce the boundary artifacts that normally occur in restoration processes. Preliminary numerical tests are reported on some simulated optical imaging problems in order to illustrate the effectiveness of the approach, as well as the fast convergence of our iterative scheme.Item Formação de professores que ensinam matemática : um balanço de 25 anos de pesquisa brasileira.(2002) Fiorentini, Dario; Nacarato, Adair Mendes; Ferreira, Ana Cristina; Lopes, Celi Aparecida Espasandin; Freitas, Maria Teresa Menezes; Miskulin, Rosana Giaretta SguerraEste artigo apresenta um balanço da pesquisa brasileira em 112 teses e dissertações produzidas no período 1978-2002, cujo objeto de estudo é a formação ou o desenvolvimento profissional do professor. Distribuindo os trabalhos em três focos temáticos – formação inicial, formação continuada e outros, o texto descreve e analisa essa produção detalhando-a em vários subfocos. Produz ainda um balanço síntese das dissertações e teses no qual aponta uma mudança paradigmática de concepções e métodos associados à temática a partir da década de 90, é indica temas e perspectivas aos quais fazem falta investimento e aprofundamento da investigação.Item Fórmula de recorrência para a soma de séries infinitas.(2004) Martins, João Luiz; Brandão, Adilson José VieiraIn this article we introduce a recurrence formula for certain infinite series whose terms include factors that belong to a generalized Horadam-type sequence. This recurrence formula is used to calculate the +∞ n=1 nkWnxn series sum without use of derivatives and at a lower computation cost. Some results are presented below which were obtained by numerical implementation of the recurrence formula for some particular values of k and x.Item Uma classe de séries infinitas envolvendo termos de sequências generalizadas.(2004) Martins, João Luiz; Brandão, Adilson José VieiraIn this article we introduce a recurrence formula for certain infinite series whose terms include factors that belong to a generalized Horadamtype sequence. This recurrence formula is used to calculate the sum of the series X +∞ n=1 n kWnx n without the need of derivatives and at a lower computational cost. Some results are apresented below which were obtained by numerical implementation of the recurrence formula for some particular values of k and x.Item Approximate analytical formulas for Kirchhoff migration operator.(2005) Martins, João LuizTwo important tools in seismic processing––Kirchhoff migration and demigration operators –– are the basis for many imaging problems solution. Due to high numerical and computational requirements, the use of those tools for three dimensions are very computation-costly. This fact has motivated us to investigate Kirchhoff migration operations for simpler types of media in order to provide faster results to be used as an approximation for more realistic media. To obtain results with lower computational effort, a convenient environment is the so called 2.5D situation, i.e., considering 3-D wave propagation in a medium that does not vary in the horizontal direction perpendicular to the seismic line. In this case, 2-D ray-tracing is sufficient to describe the 3-D propagation effects, particularly geometric-spreading. In a medium where the parameters depend only on the depth component (1-D situation), the imaging operations only require the solution of semi-analytical integrals, which can be both precisely and immediately implemented. For some particular cases of vertical velocity distributions, approximate analytical formulas are devised for migration stacking-lines and weight functions. Several imaging algorithms present very efficient computational performance by using those models. Thus, it is possible to establish a set of cases which may be useful for validating the implementation of more complex situations.Item Buffer allocation in general single-server queueing networks.(2007) Cruz, Frederico Rodrigues Borges da; Duarte, Anderson Ribeiro; Van Woensel, TomThe optimal buffer allocation in queueing network systems is a difficult stochastic, non-linear, integer mathematical programming problem. Moreover, the objective function, the constraints or both are usually not available in closed form, making the problem even harder. A good approximation for the performance measures is thus essential for a successful buffer allocation algorithm. A recently published two-moment approximation formula to obtain the optimal buffer allocation in general service time single queues is examined in detail, based on which a new algorithm is proposed for the buffer allocation in single-server general service time queueing networks. Computational results and simulation results are shown to evaluate the efficacy of the approach in generating optimal buffer allocation patterns.Item Existence and multiplicity of positive solutions for the p-Laplacian with nonlocal coefficient.(2008) Bueno, Hamilton Prado; Ercole, Grey; Ferreira, Wenderson Marques; Santos, Antônio Zumpano PereiraWe consider the Dirichlet problem with nonlocal coefficient given by −a(Ω|u|q dx)_pu = w(x)f (u) in a bounded, smooth domain Ω ⊂ Rn (n _ 2), where _p is the p-Laplacian, w is a weight function and the nonlinearity f (u) satisfies certain local bounds. In contrast with the hypotheses usually made, no asymptotic behavior is assumed on f . We assume that the nonlocal coefficient a(_Ω|u|q dx) (q _ 1) is defined by a continuous and nondecreasing function a : [0,∞)→[0,∞) satisfying a(t) > 0 for t > 0 and a(0) _ 0. A positive solution is obtained by applying the Schauder Fixed Point Theorem. The case a(t) = tγ/q (0 < γ < p − 1) will be considered as an example where asymptotic conditions on the nonlinearity provide the existence of a sequence of positive solutions for the problem with arbitrarily large sup norm.Item Theoretical analysis and control results for the FitzHugh-Nagumo equation.(2008) Brandão, Adilson José Vieira; Fernandez Cara, Enrique; Magalhães, Paulo Marcelo Dias de; Rojas Medar, Marko AntonioIn this paper we are concerned with some theoretical questions for the FitzHugh-Nagumo equation. First, we recall the system, we briefly explain the meaning of the variables and we present a simple proof of the existence and uniqueness of strong solution. We also consider an optimal control problem for this system. In this context, the goal is to determine how can we act on the system in order to get good properties. We prove the existence of optimal state-control pairs and, as an application of the Dubovitski-Milyoutin formalism, we deduce the corresponding optimality system. We also connect the optimal control problem with a controllability question and we construct a sequence of controls that produce solutions that converge strongly to desired states. This provides a strategy to make the system behave as desired. Finally, we present some open questions related to the control of this equation.Item A teoria social cognitiva e o ensino-aprendizagem da matemática : considerações sobre as crenças de autoeficácia matemática.(2009) Torisu, Edmilson Minoru; Ferreira, Ana CristinaO objetivo desse ensaio é comentar, brevemente, a Teoria Social Cognitiva, idealizada por Albert Bandura e discutir o papel do construto autoeficácia no contexto escolar, mais especificamente no ensino e aprendizagem da Matemática. As crenças de autoeficácia constituem a base da motivação de um indivíduo e se relacionam com a autopercepção do mesmo sobre seu próprio potencial. A literatura indica que alunos que desenvolvem crenças de autoeficácia mais robustas dedicar-se-ão por mais tempo e com mais empenho a uma tarefa, tendo mais chances de lograr êxito. Considerando o desempenho dos alunos brasileiros em Matemática (SIMAVE, Prova Brasil e outros) na última década, temos um quadro preocupante. Nesse sentido, o desenvolvimento de crenças de autoeficácia mais robustas poderia contribuir para a construção de uma relação mais favorável com a Matemática e para um melhor desempenho dos estudantes. Para isso, são necessários estudos que investiguem a influência das crenças de autoeficácia sobre a motivação e o desempenho dos mesmos, bem como a criação de estratégias para seu desenvolvimento. Esse ensaio é um primeiro passo nessa direção, tendo em vista a escassez de estudos nessa área, relacionados à Matemática.Item Computing the first eigenvalue of the p-Laplacian via the inverse power method.(2009) Biezuner, Rodney Josué; Ercole, Grey; Martins, Eder MarinhoIn this paper, we discuss a new method for computing the first Dirichlet eigenvalue of the p-Laplacian inspired by the inverse power method in finite dimensional linear algebra. The iterative technique is independent of the particular method used in solving the p-Laplacian equation and therefore can be made as efficient as the latter. The method is validated theoretically for any ball in Rn if p >1 and for any bounded domain in the particular case p = 2. For p >2 the method is validated numerically for the square.Item Relação com o saber matemático de alunos em risco de fracasso escolar.(2010) Oliveira, Simone Amorim Castro Kiefer; Moreira, Plínio CavalcantiNeste artigo relatamos uma pesquisa cujo objetivo foi conhecer as relações com o saber de um grupo específico de alunos de duas escolas do Ensino Fundamental, uma pública e uma particular. Esse grupo é composto por alunos da oitava série (nono ano) que se encontram em situação de risco de fracasso em matemática. Queríamos compreender as relações com o saber dos alunos desse grupo, frente às de alunos pertencentes a outro grupo na mesma sala de aula, sendo este último composto por aqueles considerados “bemsucedidos” em matemática. Os instrumentos de coleta de dados foram entrevistas com os alunos de ambos os grupos e com suas famílias, aplicação de questionários e testes de conhecimento matemático. Os resultados mostram que há diferenças significativas entre os alunos dos dois grupos, não apenas no conhecimento matemático, mas em todos os seis aspectos pesquisados da relação com o saber.Item Structural and physical–chemical evaluation of bradykinin potentiating peptide and its high soluble supramolecular complex.(2010) Sousa, Frederico Barros de; Denadai, Ângelo Márcio Leite; Lula, Ivana Silva; Ianzer, Danielle Alves; Malaspina, Érica Resende; Camargo, Antônio Carlos Martins de; Santos, Robson Augusto Souza dos; Sinisterra, Ruben DarioThe supramolecular interactions between a Bradykinin Potentiating Peptide (BPP10c) and b-cyclodextrin (bCD) have been investigated by using several techniques. These new properties acquired by the inclusion phenomena are important in developing a strategy for pharmaceutical formulation. The BPP10c structural elucidation and its inclusion complex formed have been investigated using Nuclear Magnetic Resonance techniques. The peptide secondary structure was investigated using infrared spectroscopy in solution, Circular Dichroism and NMR. In addition, the thermodynamic parameters of the inclusion process were also evaluated using Isothermal Titration Calorimetry. The results obtained by these physical– chemical techniques suggested a 1:1 complex formed by interaction between the Tryptophan amino acid residue and the bCD cavity. The peptide secondary structure was not substantially modified for the inclusion process. In addition, the inclusion process proved to be spontaneous (DG8 = -2.53 kcal mol-1), with an enthalpy reduction (DH8 = -3.72 kcal mol-1) and a favored entropic variation (TDS8 = -1.19 kcal mol-1).Item Penalized likelihood and multi-objective spatial scans for the detection and inference of irregular clusters.(2010) Cançado, André Luiz Fernandes; Duarte, Anderson Ribeiro; Duczmal, Luiz Henrique; Ferreira, Sabino José; Fonseca, Carlos M.; Gontijo, Eliane DiasBackground: Irregularly shape d spatial clusters are difficult to delineate. A cluster found by an algorithm often spreads through large portions of the map, impacting its geographical meaning. Penalized likelihood methods for Kulldorff’ s spatial scan statistics have been used to control the excessive freedom of the shape of clusters . Penalty functions based on cluster geometry and non-connectivity have been proposed recently. Another approach involves the use of a multi objective algorithm to maximize two objectives: the spatial scan statistics and the geometric penalty function. Results & Discussion: We present a novel scan statistic algorithm employing a function based on the graph topology to penalize the presence of under -populated disconnection nodes in candid ate clusters , the disconnection nodes cohesion function. A disconnection node is defined as a region within a cluster, such that its removal disconnects the cluster. By applying this function , the most geographicall y meaning ful clusters are sifted through the immense set of possible irregularly shaped candidate cluster solutions. To evaluate the statistical significance of solutions for multi-objective scans, a statistical approach based on the concept of attainment function is use d. In this pa per we compared different penalized likelihoods employing the geometric and non-connectivity regularity functions and the novel disconnection nodes cohesion function . We also build multi-objective scans using those three functions and compare them with the previous penalized likelihood scans. An application is presented using comprehensive state-wide data for Chagas’ disease in puerperal women in Minas Gerais state, Brazil. Conclusions : We show that, compared to the other single-objective algorithm s, multi- objective scans present better performance, regarding power, sensitivity and positive predicted value. The multi objective non-connectivity scan is faster and better suited for the detect ion of moderately irregularly shaped clusters. The multi-objective cohesion scan is most effective for the detection of highly irregularly shaped clusters .Item Computing the sinP Function via the inverse power method.(2010) Biezuner, Rodney Josué; Ercole, Grey; Martins, Eder MarinhoIn this paper, we discuss a new iterative method for computing sinp. This function was introduced by Lindqvist in connection with the unidimensional nonlinear Dirichlet eigenvalue problem for the p-Laplacian. The iterative technique was inspired by the inverse power method in finite dimensional linear algebra and is competitive with other methods available in the literature.Item Uma proposta para a detecção do adequado período de aquecimento em modelos de simulação.(2011) Norato, Hélida Mara Gomes; Duarte, Anderson RibeiroA seleção de um período de aquecimento adequado para uma simulação de eventos discretos ainda é uma escolha de difícil determinação. Alguns métodos já foram desenvolvidos e serão brevemente revistos, aqui. Ainda não existem critérios definitivos para a escolha de um método específico dentre os existentes. Buscamos discutir alguns dos métodos existentes e apresentar um método que se adapte bem à estrutura do modelo em estudo. Analisaremos o desempenho dos métodos expostos, através de um procedimento avaliativo para comparação. Os métodos serão aplicados para as saídas geradas por um modelo simples de trabalho com diferentes níveis de utilização. Algumas métricas serão utilizadas para averiguação da eficiência de cada um dos métodos, em comparação com a nova proposta implementadaItem Is knowledge of a non-dominant L2 activated by bilinguals using their dominant L1? Insights from an on-line psycholinguistic study.(2011) Souza, Ricardo Augusto de; Oliveira, Fernando Luiz Pereira deL1 influences on L2 learning and use are phenomena vastlydocumented in L2 learning research (ODLIN, 1989; JARVIS & PAVLEN-KO, 2007). However, approaches to the inversed phenomenon, i.e.: L2 influences on L1, are more recent (COOK, 2003). Studies of L2 e" ectson the L1 tend to examine bilinguals living in the linguistic environmentsof the L2. In the present study, we report the results of a psycholinguis-tic study that suggests that bilinguals who probably have their L1 as thedominant language may nonetheless activate L2 semantics-syntax inter-face representations over the course of sentence processing. We discussour results with respect to their implications for the cognitive architectureof bilinguals’ language representations, as well as what they might signifyfor language contact situations.Item Usando tecnologias da informação e comunicação no ensino de geometria analítica plana : explorando os conceitos de feixe de retas paralelas e concorrentes.(2011) Santos, Ivan Nogueira dos; Reis, Frederico da SilvaO presente trabalho apresenta um recorte de nossa pesquisa de dissertação que está sendo desenvolvida no Mestrado Profissional em Educação Matemática da Universidade Federal de Ouro Preto. Inicialmente, fazemos uma breve revisão teórico-bibliográfica contemplando alguns trabalhos relacionados à utilização de Tecnologias da Informação e Comunicação no ensino de Geometria Analítica Plana. A parte da pesquisa de campo aqui relatada e analisada refere-se à elaboração, implementação e avaliação de uma atividade exploratória sobre retas, em Laboratório de Informática, com alunos do curso de Licenciatura em Matemática da UFOP matriculados na disciplina Geometria Analítica Plana. As considerações parciais apontam a possibilidade de visualização de conceitos e propriedades, a realização de experimentações, com ênfase na interpretação de construções geométrico-gráficas e o dinamismo do ambiente de aprendizagem como as principais contribuições da utilização de tecnologias para o ensino de Geometria Analítica Plana.Item On capability indices for multivariate autocorrelated processes.(2011) Mingoti, Sueli Aparecida; Oliveira, Fernando Luiz Pereira deIn this paper the effects of the autocorrelation on some multivariate capability indices commonly used for independent processes are discussed and a correction is proposed. Some results are shown for VARMA(1,1) and VAR(1) time series processes under the multivariate normality assumption and the proportion of non-conforming units is calculated for some bivariate VAR(1) models. An extension of Veevers capability index for non-centered processes is also a subject addressed in this paper. An example of application in blast charcoal furnace pig iron process is presented and bootstrap is used to build confidence intervals for its true capability value as well as to evaluate the performance of the capability estimators. Similar as to what is already known for univariate processes the results showed that autocorrelation has a large impact in the multivariate capabilities indices. This paper also shows that some care should be taken when using Niverthi and Dey’s capabilities indices since they are very sensitive to any deviations from the process means to the specification means up to a point that a capable process might be considered non-capable.Item Nonparametric intensity bounds for the delineation of spatial clusters.(2011) Oliveira, Fernando Luiz Pereira de; Duczmal, Luiz Henrique; Cançado, André Luiz Fernandes; Tavares, RicardoBackground: There is considerable uncertainty in the disease rate estimation for aggregated area maps, especially for small population areas. As a consequence the delineation of local clustering is subject to substantial variation. Consider the most likely disease cluster produced by any given method, like SaTScan, for the detection and inference of spatial clusters in a map divided into areas; if this cluster is found to be statistically significant, what could be said of the external areas adjacent to the cluster? Do we have enough information to exclude them from a health program of prevention? Do all the areas inside the cluster have the same importance from a practitioner perspective? Results: We propose a method to measure the plausibility of each area being part of a possible localized anomaly in the map. In this work we assess the problem of finding error bounds for the delineation of spatial clusters in maps of areas with known populations and observed number of cases. A given map with the vector of real data (the number of observed cases for each area) shall be considered as just one of the possible realizations of the random variable vector with an unknown expected number of cases. The method is tested in numerical simulations and applied for three different real data maps for sharply and diffusely delineated clusters. The intensity bounds found by the method reflect the degree of geographic focus of the detected clusters. Conclusions: Our technique is able to delineate irregularly shaped and multiple clusters, making use of simple tools like the circular scan. Intensity bounds for the delineation of spatial clusters are obtained and indicate the plausibility of each area belonging to the real cluster. This tool employs simple mathematical concepts and interpreting the intensity function is very intuitive in terms of the importance of each area in delineating the possible anomalies of the map of rates. The Monte Carlo simulation requires an effort similar to the circular scan algorithm, and therefore it is quite fast. We hope that this tool should be useful in public health decision making of which areas should be prioritized.Item Índices de capacidade para processos multivariados independentes : extensões dos índices de Niverthi e Dey e Mingoti e Glória.(2011) Mingoti, Sueli Aparecida; Oliveira, Fernando Luiz Pereira de; Conceição, Míriam Márcia Carvalho daNeste artigo apresentamos dois novos índices de capacidade multivariados para processos independentes que são extensões do coeficiente de capacidade univariado Cpm. Esses novos índices foram formulados de acordo com as ideias de Niverthi e Dey (2000) e Mingoti e Glória (2008) e são sensíveis a diferenças entre as médias de especificação e de processo. Uma comparação entre os índices foi realizada considerando-se vários cenários diferentes e mostrou que o novo coeficiente construído com base na formulação de Mingoti e Glória teve um desempenho melhor que o fundamentado na formulação de Niverthi e Dey, embora ambos tenham se mostrado adequados para avaliar a capacidade de processos multivariados não centrados. Para construção de intervalos de confiança para o índice de capacidade real do processo foi empregada a metodologia Bootstrap. A qualidade dos estimadores dos coeficientes de capacidade foi avaliada por simulação de Monte Carlo.