Browsing by Author "Gatica, Gabriel N."
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- ItemA direct coupling of local discontinuous Galerkin and bounsary elemt methods(2010) Gatica, Gabriel N.; Heuer, Norbert; Sayas, Francisco Javier
- ItemA dual-dual formulation for the coupling of mixed-FEM and BEM in hyperelasticity(2000) Gatica, Gabriel N.; Heuer, Norbert
- ItemA posteriori error estimates for a mixed-FEM formulation of a non-linear elliptic problem(2002) Araya, Rodolfo; Barrios, Tomás P.; Gatica, Gabriel N.; Heuer, Norbert
- ItemA preconditioned MINRES method for the coupling of mixed-FEM and BEM for some nonlinear problems(2002) Gatica, Gabriel N.; Heuer, Norbert
- ItemA priori and a posteriori error analysis of an augmented mixed finite element method for incompressible fluid flows(2008) Figueroa, Leonardo E.; Gatica, Gabriel N.; Heuer, Norbert
- ItemA residual based a posteriori error estimator for an augmented mixed finite element method in linear elasticity(2006) Barrios, Tomás P.; Gatica, Gabriel N.; González, María; Heuer, Norbert
- ItemAn a posteriori error estimate for a linear-nonlinear transmission problem in plane elastostatics(2002) Barrientos, Mauricio A.; Gatica, Gabriel N.; Heuer, Norbert
- ItemAn expanded mixed finite element approach via a dual-dual formulation and the minimum residual method(2001) Gatica, Gabriel N.; Heuer, Norbert
- ItemAn implicit-explicit residual error estimator for the coupling of dual-mixed finite elements and boundary elements in elastostatics(2001) Gatica, Gabriel N.; Heuer, Norbert; Stephan, Ernst P.
- ItemConjugate gradient method for dual-dual mixed formulations(2002) Gatica, Gabriel N.; Heuer, Norbert
- ItemCoupling of mixed finite element and stabilized boundary element methods for a fluid-solid interaction problem in 3D(2014) Gatica, Gabriel N.; Heuer, Norbert; Meddahi, S.
- ItemLinear Control applied to a non-isolated bidirectional DC-DC converter with Interleave technique powered by variable sources(IEEE, 2019) Salgado, J.; Rojas, F.; Pereda Torres, Javier Eduardo; Díaz, M.; Gatica, Gabriel N.In this article, a linear control strategy is presented applied to a Synchronous Buck converter, which allows N sub-converters to operate in parallel, operating in Interleave mode, balancing the currents in each of the sub-converters and maintaining their dynamic response invariant over a wide range of operation, even when their DC links vary as it would be in a system with electric batteries. Simulation results validating this behavior, using variable DC sources are presented and discussed in this article.
- ItemMinimum residual iteration for a dual-dual mixed formulation of exterior transmission problems(2001) Gatica, Gabriel N.; Heuer, Norbert
- ItemNumerical Analysis & No Regrets. Special Issue Dedicated to the Memory of Francisco Javier Sayas (1968-2019)(WALTER DE GRUYTER GMBH, 2022) Gatica, Gabriel N.; Heuer, Norbert; Meddahi, SalimThis is the preface of a special issue dedicated to the memory of Francisco Javier Sayas who passed away on April 2, 2019. The articles reflect Sayas' main research interests in the numerical analysis of partial differential equations, containing contributions on the scattering and propagation of acoustic and electromagnetic waves, and the analysis of discontinuous Galerkin schemes, boundary element methods, and coupled schemes. We discuss the main contributions of Sayas and give an overview of the results covered by this special issue.
- ItemOn the numerical analysis of nonlinear twofold saddle point problems(2003) Gatica, Gabriel N.; Heuer, Norbert; Meddahi, Salim
- ItemPhase-shifted Pulse Width Modulation with alternate zeros voltage for parallel connection of H-Bridges for High-Current Low-Voltage applications(IEEE, 2019) Verdugo, D.; Rojas, F.; Lillo, J.; Diaz, M.; Pereda Torres, Javier Eduardo; Gatica, Gabriel N.Phase-Shifted Modulation (PSM) applied to multilevel converters is an effective method for reducing the output THD. In this paper, a new unipolar PSM method is proposed to control internal circulating current of a high-current low-voltage power converter, composed of parallel connected H- Bridges. The proposed method reduces the H-bridge currents distortions and the power losses of the overall converter. Simulation results comparing the standard unipolar modulation with the proposed unipolar modulation technique are performed to demonstrate its effectiveness.
- ItemPrimal and Mixed Finite Element Methods for Deformable Image Registration Problems(2018) Barnafi, Nicolas; Gatica, Gabriel N.; Hurtado Sepúlveda, Daniel
- ItemPrimal and mixed finite element methods for image registration.(2017) Barnafi Wittwer, Nicolás Alejandro; Hurtado Sepúlveda, Daniel; Gatica, Gabriel N.; Pontificia Universidad Católica de Chile. Escuela de IngenieríaLa registración deformable de imágenes (DIR) representa un poderoso método computacional para analizar imágenes, con prometedoras aplicaciones en el diagnóstico en enfermedades humanas. A pesar de ser ampliamente usado en la comunidad de imágenes médicas, el análisis matemático y numérico de métodos de DIR sigue abierto. Además, aplicaciones recientes de DIR incluyen la cuantificación de indicadores mecánicos además de la transformación de alineamiento, lo que justifica el desarrollo de formulaciones novedosas de DIR donde la precisión y convergencia de campos que no sean el alineamiento pueden ser estudiadas. En este trabajo proponemos y analizamos formulaciones primal, mixta y aumentada para DIR, junto con su esquema de discretización de elementos finitos para su resolución numérica. La formulación variacional de DIR equivale a un problema de elasticidad lineal con un término fuente que depende no-linealmente de la alineación. Argumentos de punto fijo y supuestos de datos pequeños son utilizados para obtener la correcta formulación tanto del esquema continuo como del discreto para todas las formulaciones. En particular, elementos lineales por tramo para el desplazamiento en el caso primal, elementos Brezzi-Douglas-Marini de orden 1 (resp. Raviart-Thomas de orden 0) para la tensión junto con constantes por tramo (resp. lineal por tramo) para el desplazamiento para el esquema mixto (resp. aumentado), constituyen elecciones factibles que garantizan la estabilidad de los sistemas de Galerkin asociados. Estimaciones de error a priori se obtuvieron usando lemas de tipo Strang, y sus asociadas tasas de convergencia de acuerdo a propiedades de aproximación se muestran también. Ensayos de convergencia numérica y ejemplos de DIR se incluyen para mostrar la aplicabilidad del método.
- ItemSpecial Issue: Fourth Chilean Workshop on Numerical Analysis of Partial Differential Equations (WONAPDE 2013), Universidad de Concepción, Chile(2015) Bürger, Raimund; Gatica, Gabriel N.; Heuer, Norbert; Rodriguez, Rodolfo; Sepúlveda, Mauricio
- ItemThe Boundary Element Method with Lagrangian Multipliers(2009) Gatica, Gabriel N.; Healey, Martin; Heuer, Norbert