Now showing items 1-20 of 120

    • A Geometric Toolbox for Tetrahedral Finite Element Partitions 

      Brandts J.; Korotov S.; Křížek M. (Efficient Preconditioned Solution Methods for Elliptic Partial Differential Equations, 2011-12-31)
      In this work we present a survey of some geometric results on tetrahedral partitions and their refinements in a unified manner. They can be used for mesh generation and adaptivity in practical calculations by the finite ...
    • A hybrid method for inversion of 3D DC resistivity logging measurements 

      Gajda-Zagórska E.; Schaefer R.; Smolka M.; Paszynski M.; Pardo D. (Natural Computing, 2014-12-31)
      This paper focuses on the application of hp hierarchic genetic strategy (hp-HGS) for solution of a challenging problem, the inversion of 3D direct current (DC) resistivity logging measurements. The problem under consideration ...
    • A modified discontinuous Galerkin method for solving efficiently Helmholtz problems 

      Grigoroscuta-Strugaru M.; Amara M.; Calandra H.; Djellouli R. (Communications in Computational Physics, 2012-12-31)
      A new solution methodology is proposed for solving efficiently Helmholtz problems. The proposed method falls in the category of the discontinuous Galerkin methods. However, unlike the existing solution methodologies, this ...
    • A posteriori error analysis of a stabilized mixed FEM for convectuion-diffusion problems 

      Gonzalez M.; Jansson J.; Korotov S. (AIMS Proceedings, 2015, 2015-12-31)
      We present an augmented dual-mixed variational formulation for a linear convection-diffusion equation with homogeneous Dirichlet boundary conditions. The approach is based on the addition of suitable least squares type ...
    • A posteriori error analysis of an augmented mixed finite element method for Darcy flow 

      Barrios T.P.; Cascón J.M.; Gonzalez M. (Computer Methods in Applied Mechanics and Engineering, 2015-12-31)
      We develop an a posteriori error analysis of residual type of a stabilized mixed finite element method for Darcy flow. The stabilized formulation is obtained by adding to the standard dual-mixed approach suitable residual ...
    • A Secondary Field Based hp-Finite Element Method for the Simulation of Magnetotelluric Measurements 

      Alvarez-Aramberri J.; Pardo D.; Barucq E. (Journal of Computational Science, 2015-12-31)
      In some geophysical problems, it is sometimes possible to divide the subsurface resistivity distribution as a one dimensional (1D) contribution plus some two dimensional (2D) inhomogeneities. Assuming this scenario, we ...
    • A stable discontinuous Galerkin-type method for solving efficiently Helmholtz problems 

      Amara M.; Calandra H.; Dejllouli R.; Grigoroscuta-Strugaru M. (Computers and Structures, 2012-12-31)
      We propose a stable discontinuous Galerkin-type method (SDGM) for solving efficiently Helmholtz problems. This mixed-hybrid formulation is a two-step procedure. Step 1 consists in solving well-posed problems at the element ...
    • A study of the apsidal angle and a proof of monotonicity in the logarithmic potential case 

      Castelli R. (Journal of Mathematical Analysis and Applications, 2014-12-31)
      This paper concerns the behaviour of the apsidal angle for orbits of central force system with homogeneous potential of degree $-2 \le \alpha \le 1$ and logarithmic potential. We derive a formula for the apsidal angle as ...
    • Accessibility for Line-Cutting in Freeform Surfaces 

      van Sosin B.; Bartoň M.; Elber G. (Computer-Aided Design, 2019-04-26)
      Manufacturing techniques such as hot-wire cutting, wire-EDM, wire-saw cutting, and flank CNC machining all belong to a class of processes called line-cutting where the cutting tool moves tangentially along the reference ...
    • Adjoint-based formulation for computing derivatives with respect to bed boundary positions in resistivity geophysics 

      Chaumont-Frelet T.; Shahriari M.; Pardo D. (Computational Geosciences, 2019-02)
      In inverse geophysical resistivity problems, it is common to optimize for specific resistivity values and bed boundary positions, as needed, for example, in geosteering applications. When using gradient-based inversion ...
    • An Agent-Oriented Hierarchic Strategy for Solving Inverse Problems 

      Smolka M.; Schaefer R.; Paszynski M.; Pardo D.; Alvarez-Aramberri J. (International Journal of Applied Mathematics and Computer Science, 2015-12-31)
      The paper discusses the complex, agent-oriented hierarchic memetic strategy (HMS) dedicated to solving inverse parametric problems. The strategy goes beyond the idea of two-phase global optimization algorithms. The global ...
    • An IMEX scheme combined with Richardson extrapolation methods for some reaction-diffusion equations 

      Faragó I.; Izsák F.; Szabó T. (Idojaras, 2013-12-31)
      An implicit-explicit (IMEX) method is combined with some so-called Richardson extrapolation (RiEx) methods for the numerical solution of reaction-diffusion equations with pure Neumann boundary conditions. The results are ...
    • An IMEX scheme for reaction-diffusion equations: Application for a PEM fuel cell model 

      Faragó I.; Izsák F.; Szabó T.; Kriston Á. (Central European Journal of Mathematics, 2013-12-31)
      An implicit-explicit (IMEX) method is developed for the numerical solution of reaction-diffusion equations with pure Neumann boundary conditions. The corresponding method of lines scheme with finite differences is analyzed: ...
    • Analysis of extreme wave events on the southern coast of Brazil 

      Guimaraes P.V.; Farina L.; Toldo E.E. (Natural Hazards and Earth System Sciences, 2014-12-31)
      Using the wave model SWAN (simulating waves nearshore), high waves on the southwestern Atlantic generated by extra-tropical cyclones are simulated from 2000 to 2010, and their impact on the Rio Grande do Sul (RS) coast is ...
    • Arithmetic method of double-injection-electrode model for resistivity measurement through metal casing 

      Chen Q.; Pardo D.; Li H.-B.; Wang F.-R.; Ye Q.-Z. (IEEE Transactions on Geoscience and Remote Sensing, 2010-12-31)
      Through-casing resistivity (TCR) measurement instruments such as Cased Hole Formation Resistivity are extensively used for the dynamic monitoring of oil reservoirs during the production phase in oil wells to evaluate the ...
    • Asymptotic Models for the Electric Potential across a Highly Conductive Casing 

      Erdozain A.; Péron V.; Pardo D. (Computers and Mathematics with Applications, 2018-07)
      We analyze a configuration that involves a steel-cased borehole, where the casing that covers the borehole is considered as a highly conductive thin layer. We develop an asymptotic method for deriving reduced problems ...
    • Automatic fitting of conical envelopes to free-form surfaces for flank CNC machining 

      Bo P.; Bartoň M.; Pottmann H. (Computer Aided Design, 2017-10)
      We propose a new algorithm to detect patches of free-form surfaces that can be well approximated by envelopes of a rotational cone under a rigid body motion. These conical envelopes are a preferable choice from the ...
    • Automatic Red-Channel underwater image restoration 

      Galdran A.; Pardo D.; Picón A.; Alvarez-Gila A. (Journal of Visual Communication and Image Representation, 2015-12-31)
      Underwater images typically exhibit color distortion and low contrast as a result of the exponential decay that light suffers as it travels. Moreover, colors associated to different wavelengths have different attenuation ...
    • Computational cost estimates for parallel shared memory isogeometric multi-frontal solvers 

      Wozniak M.; Kuznik K.; Paszynski M.; Calo V.M.; Pardo D. (Computers and Mathematics with Applications, 2014-12-31)
      In this paper we present computational cost estimates for parallel shared memory isogeometric multi-frontal solvers. The estimates show that the ideal isogeometric shared memory parallel direct solver scales as $\mathcal{O}( ...
    • Computational cost of isogeometric multi-frontal solvers on parallel distributed memory machines 

      Wozniak M.; Paszynski M.; Pardo D.; Dalcin L.; Calo V.M. (Computer Methods in Applied Mechanics and Engineering, 2015-12-31)
      This paper derives theoretical estimates of the computational cost for isogeometric multi-frontal direct solver executed on parallel distributed memory machines. We show theoretically that for the $C^{p-1}$ global continuity ...