Examinando por Materia "Mathematical techniques"

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    Integration-Free analysis of nonsmooth local dynamics in planar filippov systems
    (WORLD SCIENTIFIC PUBL CO PTE LTD, 2009-03-01) Arango, Ivan; Taborda, John Alexander; Arango, Ivan; Taborda, John Alexander; Universidad EAFIT. Departamento de Ingeniería Mecánica; Mecatrónica y Diseño de Máquinas
    In this paper, we present a novel method to analyze the behavior of discontinuous piecewise-smooth autonomous systems (denominated Filippov systems) in the planar neighborhood of the discontinuity boundary (DB). The method uses the evaluation of the vector fields on DB to analyze the nonsmooth local dynamics of the Filippov system without the integration of the ODE sets. The method is useful in the detection of nonsmooth bifurcations in Filippov systems. We propose a classification of the points, events and events combinations on DB. This classification is more complete in comparison with the others previously reported. Additional characteristics as flow direction and sliding stability are included explicitly. The lines and the points are characterized with didactic symbols and the exclusive conditions for their existence are based on geometric criterions. Boolean-valued functions are used to formulate the conditions of existence. Different problems are analyzed with the proposed methodology. © 2009 World Scientific Publishing Company.
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    Ítem
    Reduction of speckle noise in digital holography by using digital image processing
    (ELSEVIER GMBH, URBAN & FISCHER VERLAG, 2005-01-01) Garcia-Sucerquia, J; Ramirez, JAH; Prieto, DV; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica Aplicada
    A fundamental problem in optical and digital holography is the presence of speckle noise in the reconstruction process. Many approaches have been carried out in order to overcome such a problem ranging from modifying the spatial coherence of the illumination (optical techniques) to image processing techniques (digital techniques). This work shows the merged use of digital image processing techniques in order to reduce the speckle noise in digital reconstruction of optically recorded Fresnel's holograms. The proposed filtering techniques are illustrated with experimental results. © 2005 Elsevier GmbH. All rights reserved.