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A Geometric Toolbox for Tetrahedral Finite Element Partitions
(Efficient Preconditioned Solution Methods for Elliptic Partial Differential Equations, 20111231)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
(Natural Computing, 20141231)This paper focuses on the application of hp hierarchic genetic strategy (hpHGS) 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
(Communications in Computational Physics, 20121231)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 convectuiondiffusion problems
(AIMS Proceedings, 2015, 20151231)We present an augmented dualmixed variational formulation for a linear convectiondiffusion 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
(Computer Methods in Applied Mechanics and Engineering, 20151231)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 dualmixed approach suitable residual ... 
A Secondary Field Based hpFinite Element Method for the Simulation of Magnetotelluric Measurements
(Journal of Computational Science, 20151231)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 Galerkintype method for solving efficiently Helmholtz problems
(Computers and Structures, 20121231)We propose a stable discontinuous Galerkintype method (SDGM) for solving efficiently Helmholtz problems. This mixedhybrid formulation is a twostep procedure. Step 1 consists in solving wellposed problems at the element ... 
A study of the apsidal angle and a proof of monotonicity in the logarithmic potential case
(Journal of Mathematical Analysis and Applications, 20141231)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 ... 
An AgentOriented Hierarchic Strategy for Solving Inverse Problems
(International Journal of Applied Mathematics and Computer Science, 20151231)The paper discusses the complex, agentoriented hierarchic memetic strategy (HMS) dedicated to solving inverse parametric problems. The strategy goes beyond the idea of twophase global optimization algorithms. The global ... 
An IMEX scheme combined with Richardson extrapolation methods for some reactiondiffusion equations
(Idojaras, 20131231)An implicitexplicit (IMEX) method is combined with some socalled Richardson extrapolation (RiEx) methods for the numerical solution of reactiondiffusion equations with pure Neumann boundary conditions. The results are ... 
An IMEX scheme for reactiondiffusion equations: Application for a PEM fuel cell model
(Central European Journal of Mathematics, 20131231)An implicitexplicit (IMEX) method is developed for the numerical solution of reactiondiffusion 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
(Natural Hazards and Earth System Sciences, 20141231)Using the wave model SWAN (simulating waves nearshore), high waves on the southwestern Atlantic generated by extratropical cyclones are simulated from 2000 to 2010, and their impact on the Rio Grande do Sul (RS) coast is ... 
Arithmetic method of doubleinjectionelectrode model for resistivity measurement through metal casing
(IEEE Transactions on Geoscience and Remote Sensing, 20101231)Throughcasing 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 ... 
Automatic fitting of conical envelopes to freeform surfaces for flank CNC machining
(Computer Aided Design, 201710)We propose a new algorithm to detect patches of freeform 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 RedChannel underwater image restoration
(Journal of Visual Communication and Image Representation, 20151231)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 multifrontal solvers
(Computers and Mathematics with Applications, 20141231)In this paper we present computational cost estimates for parallel shared memory isogeometric multifrontal solvers. The estimates show that the ideal isogeometric shared memory parallel direct solver scales as $\mathcal{O}( ... 
Computational cost of isogeometric multifrontal solvers on parallel distributed memory machines
(Computer Methods in Applied Mechanics and Engineering, 20151231)This paper derives theoretical estimates of the computational cost for isogeometric multifrontal direct solver executed on parallel distributed memory machines. We show theoretically that for the $C^{p1}$ global continuity ... 
Computational fixedpoint theory for differential delay equations with multiple time lags
(Journal of Differential Equations, 20121231)We introduce a general computational fixedpoint method to prove existence of periodic solutions of differential delay equations with multiple time lags. The idea of such a method is to compute numerical approximations of ... 
Dimensionally adaptive hpfinite element simulation and inversion of 2D magnetotelluric measurements
(Journal of Computational Science, 20160901)Magnetotelluric (MT) problems often contain different subdomains where the conductivity of the media depends upon one, two, or three spatial variables. Traditionally, when a MT problem incorporates a threedimensional (3D) ... 
Direct solvers performance on hadapted grids
(Computers and Mathematics with Applications, 20151231)We analyse the performance of direct solvers when applied to a system of linear equations arising from an $h$adapted, $C^0$ finite element space. Theoretical estimates are derived for typical $h$refinement patterns arising ...