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Biblioteca Digital do IPB (53.442 recursos)

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DEMAT - Resumos em Proceedings Não Indexados ao ISI

Mostrando recursos 1 - 20 de 56

  1. Changes in the density profile due to the m=2 tearing mode in asdex

    Manso, M.E.; Silva, A.; Serra, F.; Matias, José; Mendonça, J.; Zohm, H.; Kluber, O.; Soldner, F. X.
    Resistive MHO tearing modes can develop magnetic islands near the rational magnetic surfaces, where q=m/ n.

  2. Localized density measurements on ssdex using microwave reflectometry

    Manso, M.E.; Serra, F.; Silva, A.; Matias, José; Nunes, F.; Leitão, J.; Mata, J.; Varela, P.; Vergamota, S.; Neves, J.; Pereira, J.; Cupido, L.; Soldner, F. X.; Siller, G.
    Reflectometry is based on the propagation and reflection of probing waves in the inhomogeneous fusion plasma.

  3. Angular momentum transport in the sun through meridian circulation

    Matias, José; Zahn, Jean-Paul
    We investigated the transport of angularmomentum in the radiative interior of the Sun through the mecanism describ by ZAhn (1992), namely the meridian circulation driven by the solar wind and the turbulance caused by the shear instabilities due to the differential rotation.

  4. Internal waves and angular momentum transport in the sun

    Zahn, Jean-Paul; Talon, Suzanne; Matias, José
    The low frequency gravity waves emitted at the base of the solar convection zone are able to extract angularmomentumfrom the radiative interior.

  5. Stopping rules effect on a derivative-free filter multistart algorithm for multilocal programming

    Fernandes, Florbela P.; Costa, M.F.P.; Fernandes, Edite M.G.P.
    Multilocal programming aims to identify all the local solutions of constrained optimization problems. The purpose of this paper is to analyze the effect of stopping rules on the performance of a particular multistart method, which relies on a derivative-free local search procedure to converge to a solution, when solving multilocal optimization problems. The method herein presented implements the approximate descent direction method combined with a filter methodology to handle the constraints by forcing the local search towards the feasible region. Two stopping rules are tested on five classical multimodal problems.

  6. Solving flexible job shop scheduling using genetic algorithm

    Pereira, Ana I.; Curralo, Ana; Barbosa, José; Leitão, Paulo
    This work addresses a real assembly cell: the AIP-PRIMECA cell at the Université e de Valenciennes et du Hainaut-Cambrésis, in France. This system can be viewed as a Flexible Job Shop, leading to the formulation of a Flexible Job Shop Scheduling Problem (FJSSP). This FJSSP offers the possibility to create the products "AIP", "LATE" and "BELT" using by five workstations, each one being able to perform a set of operations, that are linked using a conveyor system. The transportation between stations is achieved using a shuttle which is able to transport one product at the time, being released after the product...

  7. Golden tilings

    Pinto, Alberto A.; Almeida, João Paulo; Portela, A.
    A. Pinto and D. Sullivan [3] proved a one-to-one correspondence between: (i) Cl+ conjugacy classes of expanding circle maps; (ii) solenoid functions and (iii) Pinto-Sullivan's dyadic tilings on the real line. Here, we prove a one-to-one correspondence between: (i) golden tilings; (ii) smooth conjugacy classes of golden diffeomorphism of the circle that are fixed points of renormalization; (iii) smooth conjugacy classes of Anosov difeomorphisms, with an invariant measure absolutely continuous with respect to the Lebesgue measure, that are topologically conjugated to the Anosov automorphism G(x, y) = (x + y, x) and (iv) solenoid functions.

  8. Golden tilings

    Almeida, João Paulo; Pinto, Alberto A.
    In this talk we present the definition of a golden sequence {ri}i2N. These golden sequences have the property of being Fibonacci quasi-periodic and determine a tiling in the real line. We prove a one-to-one correspondence between: (i) affine classes of golden tilings; (ii) smooth conjugacy classes of Anosov difeomorphisms, with an invariant measure absolutely continuous with respect to the Lebesgue measure, that are topologically conjugate to the Anosov automorphism

  9. Pinto's golden tilings

    Almeida, João Paulo
    We present the definition of a golden sequence. These golden sequences are Fibonacci quasi-periodic and determine a tiling of the real line. We prove the existence of a natural one-to-one correspondence between: (i) Golden sequences; (ii) Smooth conjugacy classes of circle diffeomorphisms with golden rotation number that are smooth fixed points of renormalization, and (iii) Smooth conjugacy classes of Anosov diffeomorphisms that are topologicaly conjugate to the toral automorphism G_A=(x+y,x). The Pinto-Sullivan tilings of the real line relate smooth conjugacy classes of expanding circle maps with 2-adic sequences.

  10. Experiências com o método de redução para a resolução de problemas de programação semi-infinita

    Pereira, Ana I.; Fernandes, Edite M.G.P.
    Neste trabalho serão apresentadas diversas variantes do métodos de redução para a resolução de problemas de programação semi-infinita. Estas variantes combinam o método dos filtros com técnicas da programação semi-infinita e da programação multi-local.

  11. Cell-free layer measurements in a bifurcation microchannel : comparison between a manual and automatic methods

    Bento, David; Pinho, Diana; Pinto, Elmano; Yaginuma, Tomoko; Correia, Teresa Montenegro; Lima, José; Pereira, Ana I.; Lima, R.
    In the present work, in vitro blood flowing through a bifurcation microchannel was studied. The aim was to measure the Trajectories of the cell-free layer (CFL) by using different methods, i. e., a manual and two automatic methods.

  12. Desenvolvimento de um microdispositivo biomédico para a separação de células sanguíneas

    Novais, Susana; Pinho, Diana; Pereira, Ana I.; Mujika, Maite; Arana, Sergio; Lima, R.
    Neste trabalho procedeu-se ao desenho e implantação de um dispositivo biomédico, com capacidade de realizar a separação das células sanguíneas da camada de plasma. Numa primeira fase do trabalho realizou-se o desenho e fabricação do dispositivo, através da técnica de litografia suave. A segunda fase consistiu no estudo do escoamento sanguíneo com o objetivo de analisar o efeito das constrições na variação da espessura camada de plasma. Concluímos que a constrição proporciona um aumento da espessura da camada de plasma e à medida que se aumenta o hematócrito a camada de plasma tende a diminuir.

  13. Reduction method with multistart technique for semi-infinite programming problems

    Pereira, Ana I.; Fernandes, Florbela P.; Costa, Maria F.P.; Fernandes, Edite M.G.P.
    Semi-infinite programming problems can be efficiently solved by reduction type methods. In this work a new global reduction method for semi-infinite programming is presented. The multilocal optimization is carried out with a multistart technique and the reduced problem is approximately solved by a primal-dual interior point method combined with a two-dimensional filter line search strategy. The filter strategy is used to promote the global convergence of the algorithm. Numerical experiments with a set of well-known problems are shown and comparisons with other methods are presented.

  14. Multistart coupled with a derivative-free filter local search for locating multiple solutions

    Fernandes, Florbela P.; Pereira, Ana I.; Costa, Maria F.P.; Fernandes, Edite M.G.P.
    A multistart technique coupled with a derivative-free lter local search algorithm for locating all the optimal solutions of a nonconvex constrained optimization is presented. To reach a fast convergence to the optimal solutions, the local search procedure is based on descent directions. The lter-set concept is introduced to handle the constraints of the problem. The generated direction vector is descent for the objective function if the sample point is feasible; otherwise, it is descent for the constraint violation. Numerical experiments with benchmark problems are reported and a comparison with other stochastic methods is included.

  15. Experiences with reduction method to solve semi-infinite programming problems

    Pereira, Ana I.; Fernandes, Edite M.G.P.
    In this talk, some variants of reduction-type method combined with a line search filter method to solve nonlinear semi-infinite programming problems are presented. We use the stretched simulated annealing method and the branch and bound technique to compute the maximizers of the constraint. The filter method is used as an alternative to merit functions to promote convergence from poor starting points.

  16. Linear programming knowledge in first stage higher education courses

    Barros, Paula Maria; Pereira, Ana I.; Teixeira, Ana P.
    In this work we will describe an experimental study with approximately fifty Portuguese students of the 2nd year of the BSc Degree of Biomedical Engineering as well as Chemical and Biological Engineering Higher Education Courses. The aims of this study are to identify which knowledge of Linear Programming (LP) taught in High School the students acquired and still remember, which tools they used in that stage of education when learning the theme of LP and their opinion about the significance of LP in daily life problem resolution. We also propose to investigate if the students are able to use WinQSB...

  17. Interacção online na resolução de problemas

    Alves, Carla; Morais, Carlos; Palhares, Pedro
    A necessidade de novas estratégias de ensino e aprendizagem e o desejo de melhorar os ambientes de aprendizagem torna a utilização da Internet nas suas diversas potencialidades como um desafio para os educadores matemáticos no sentido de contribuir para colmatar dificuldades, promover competências e melhorar o sucesso em Matemática. Esta apresentação é apoiada num estudo que se encontra em curso, no âmbito de um doutoramento a realizar na Universidade do Minho. Com o estudo pretende-se averiguar a influência da utilização de estratégias suportadas por recursos online, na resolução de problemas matemáticos. Serão implementadas estratégias apoiadas na plataforma Moodle, nomeadamente, criação e...

  18. Graphical simulation of numerical algorithms - an aproach based on code instrumentation and Java technologies

    Balsa, Carlos; Alves, Luís M.; Pereira, Maria João; Rodrigues, Pedro João; Lopes, Rui Pedro
    We want to create a working tool for mathematics teachers and a corresponding learning tool for students, namely a graphical simulator of mathematical algorithms (GraSMa). To achieve it we try two different strategies. We started by annotating manually the original algorithm with inspector functions. Now we are testing a new approach that aims at automatically annotating the original code with inspector functions. To achieve this we are developing a language translator module that enables us to comment automatically on any code written in Octave language. The run of the annotated code gated by one of these two ways, records in...

  19. Análise do escoamento sanguíneo em microcanais com bifurcações

    Cidre, Diana; Oliveira, Brigitte; Lagoela, Marco; Fernandes, Carla S.; Lima, R.; Dias, Ricardo P.; Balsa, Carlos; Ishikawa, Takuji; Yamaguchi, Takami
    Vários estudos revelaram que a informação obtida sobre as propriedades reológicas do sangue em capilares de vidro difere da situação in vivo (Pries et al. 1994). As principais causas potenciais para estas discrepâncias podem ser devidas à camada superficial formada por células endoteliais e às redes microvasculares compostas por segmentos de vasos irregulares e curtos que estão ligados por numerosas bifurcações e convergências (Maeda 1996).O principal objectivo deste trabalho é analisar as propriedades não-Newtonianas do sangue durante o escoamento em modelos microvasculares. Neste estudo foi utilizado o método de litografia suave para fabricar microcanais bifurcados com secção rectangular em polidimetisiloxano...

  20. O Software open source como instrumento pedagógico: aplicação prática à econometria e à matemática

    Nunes, Alcina; Balsa, Carlos
    Em co-autoria com Alcina Nunes do Departamento de Economia e Gestão.

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