Search results for: David Pardo

Items from 1 to 20 out of 54 results

article

Semi‐blind‐trace algorithm for self‐supervised attenuation of trace‐wise coherent noise

Mohammad Mahdi Abedi, David Pardo, Tariq Alkhalifah

Geophysical Prospecting > 72 > 3 > 965 - 977

Trace‐wise noise is a type of noise often seen in seismic data, which is characterized by vertical coherency and horizontal incoherency. Using self‐supervised deep learning to attenuate this type of noise, the conventional blind‐trace deep learning trains a network to blindly reconstruct each trace in the data from its surrounding traces; it attenuates isolated trace‐wise noise but causes signal leakage...

article

Exploiting the Kronecker product structure of φ−functions in exponential integrators

Judit Muñoz‐Matute, David Pardo, Victor M. Calo

International Journal for Numerical Methods in Engineering > 123 > 9 > 2142 - 2161

Exponential time integrators are well‐established discretization methods for time semilinear systems of ordinary differential equations. These methods use

φ -

functions, which are matrix functions related to the exponential. This work introduces an algorithm to speed up the computation of the

φ -

function action over vectors for two‐dimensional (2D) matrices expressed as a Kronecker sum. For that, we...

article

Error control and loss functions for the deep learning inversion of borehole resistivity measurements

Mostafa Shahriari, David Pardo, Jon A. Rivera, Carlos Torres‐Verdín, more

International Journal for Numerical Methods in Engineering > 122 > 6 > 1629 - 1657

Deep learning (DL) is a numerical method that approximates functions. Recently, its use has become attractive for the simulation and inversion of multiple problems in computational mechanics, including the inversion of borehole logging measurements for oil and gas applications. In this context, DL methods exhibit two key attractive features: (a) once trained, they enable to solve an inverse problem...

article

Clinical and neurophysiological characteristics of patients with Guillain‐Barré syndrome at Hospital Universitario San Ignacio, Bogotá, Colombia between 2009 and 2017

Sonia Millán, Cindy Díaz, David G. David Pardo, Gabriel Castro Guzmán

Journal of the Peripheral Nervous System > 24 > 3 > 272 - 275

Guillain‐Barré syndrome (GBS) is the most common acute peripheral polyneuropathy in the world. The estimated incidence in Colombia is 1.2‐1.7 cases per 100 000 inhabitants, although during 2016 an increase in the incidence of the disease was documented, apparently associated with an epidemiological peak of the Zika virus. We conducted to describe the clinical and neurophysiological characteristics...

article

Forward‐in‐time goal‐oriented adaptivity

Judit Muñoz‐Matute, David Pardo, Victor M. Calo, Elisabete Alberdi

International Journal for Numerical Methods in Engineering > 119 > 6 > 490 - 505

In goal‐oriented adaptive algorithms for partial differential equations, we adapt the finite element mesh to reduce the error of the solution in some quantity of interest. In time‐dependent problems, this adaptive algorithm involves solving a dual problem that runs backward in time. This process is, in general, computationally expensive in terms of memory storage. In this work, we define a pseudo‐dual...

article

Fast 2.5D finite element simulations of borehole resistivity measurements

Ángel Rodríguez-Rozas, David Pardo, Carlos Torres-Verdín

Computational Geosciences > 2018 > 22 > 5 > 1271-1281

We develop a rapid 2.5-dimensional (2.5D) finite element method for simulation of borehole resistivity measurements in transversely isotropic (TI) media. The method combines arbitrary high-order H1 $H^{1}$- and H $\mathbf {H}$(curl)-conforming spatial discretizations. It solves problems where material properties remain constant along one spatial direction, over which we consider a Fourier series...

article

Goal‐oriented adaptivity using unconventional error representations for the multidimensional Helmholtz equation

Vincent Darrigrand, Ángel Rodríguez‐Rozas, Ignacio Muga, David Pardo, more

International Journal for Numerical Methods in Engineering > 113 > 1 > 22 - 42

In goal‐oriented adaptivity, the error in the quantity of interest is represented using the error functions of the direct and adjoint problems. This error representation is subsequently bounded above by element‐wise error indicators that are used to drive optimal refinements. In this work, we propose to replace, in the error representation, the adjoint problem by an alternative operator. The main...

article

Time-domain goal-oriented adaptivity using pseudo-dual error representations

Judit Muñoz-Matute, Elisabete Alberdi, David Pardo, Victor M. Calo

Computer Methods in Applied Mechanics and Engineering > 2017 > 325 > C > 395-415

Goal-oriented adaptive algorithms produce optimal grids to solve challenging engineering problems. Recently, a novel error representation using (unconventional) pseudo-dual problems for goal-oriented adaptivity in the context of frequency-domain wave-propagation problems has been developed. In this paper, we extend this error representation to the case of time-domain problems. We express the entire...

article

The value of continuity: Refined isogeometric analysis and fast direct solvers

Daniel Garcia, David Pardo, Lisandro Dalcin, Maciej Paszyński, more

Computer Methods in Applied Mechanics and Engineering > 2017 > 316 > C > 586-605

We propose the use of highly continuous finite element spaces interconnected with low continuity hyperplanes to maximize the performance of direct solvers. Starting from a highly continuous Isogeometric Analysis (IGA) discretization, we introduce C0-separators to reduce the interconnection between degrees of freedom in the mesh. By doing so, both the solution time and best approximation errors are...

article

A multi-domain decomposition-based Fourier finite element method for the simulation of 3D marine CSEM measurements

Shaaban A. Bakr, David Pardo

Computational Geosciences > 2017 > 21 > 3 > 345-357

We introduce a multi-domain decomposition Fourier finite element (MDDFFE) method for the simulation of three-dimensional (3D) marine controlled source electromagnetic measurement (CSEM). The method combines a 2D finite element (FE) method in two spatial dimensions with a hybrid discretization based on a Fourier FE method along the third dimension. The method employs a secondary field formulation rather...

article

A multi-objective memetic inverse solver reinforced by local optimization methods

Ewa Gajda-Zagórska, Robert Schaefer, Maciej Smołka, David Pardo, more

Journal of Computational Science > 2017 > 18 > C > 85-94

We propose a new memetic strategy that can solve the multi-physics, complex inverse problems, formulated as the multi-objective optimization ones, in which objectives are misfits between the measured and simulated states of various governing processes. The multi-deme structure of the strategy allows for both, intensive, relatively cheap exploration with a moderate accuracy and more accurate search...

article

Optimally refined isogeometric analysis

Daniel Garcia, Michael Bartoň, David Pardo

Procedia Computer Science > 2017 > 108 > C > 808-817

Performance of direct solvers strongly depends upon the employed discretization method. In particular, it is possible to improve the performance of solving Isogeometric Analysis (IGA) discretizations by introducing multiple C°-continuity hyperplanes that act as separators during LU factorization [8]. In here, we further explore this venue by introducing separators of arbitrary continuity. Moreover,...

article

Goal-Oriented p-Adaptivity using Unconventional Error Representations for a 1D Steady State Convection-Diffusion Problem

Vincent Darrigrand, Ángel Rodríguez-Rozas, David Pardo, Ignacio Muga

Procedia Computer Science > 2017 > 108 > C > 848-856

This work proposes the use of an alternative error representation for Goal-Oriented Adaptivity (GOA) in context of steady state convection dominated diffusion problems. It introduces an arbitrary operator for the computation of the error of an alternative dual problem. From the new representation, we derive element-wise estimators to drive the adaptive algorithm. The method is applied to a one dimensional...

article

A quadrature-free method for simulation and inversion of 1.5D direct current (DC) borehole measurements

Sergio Rojas, Ignacio Muga, David Pardo

Computational Geosciences > 2016 > 20 > 6 > 1301-1318

Resistivity inverse problems are routinely solved in order to characterize hydrocarbon bearing formations. They often require a large number of forward problems simulations. When considering a one dimensional (1D) planarly layered media, semi-analytical methods can be employed in order to solve a single forward problem in a fraction of a second. However, in some situations, a large number of (over...

article

Fusion-Based Variational Image Dehazing

Adrian Galdran, Javier Vazquez-Corral, David Pardo, Marcelo Bertalmio

IEEE Signal Processing Letters > 2017 > 24 > 2 > 151 - 155

We propose a novel image-dehazing technique based on the minimization of two energy functionals and a fusion scheme to combine the output of both optimizations. The proposed fusion-based variational image-dehazing (FVID) method is a spatially varying image enhancement process that first minimizes a previously proposed variational formulation that maximizes contrast and saturation on the hazy input...

article

A Priori Fourier Analysis for 2.5D Finite Elements Simulations of Logging-While-Drilling (LWD) Resistivity Measurements

Ángel Rodríguez-Rozas, David Pardo

Procedia Computer Science > 2016 > 80 > C > 782-791

Triaxial induction measurements provided by LWD tools generate crucial petrophysical data to determine several quantities of interest around the drilled formation under exploration, such as a map of resistivities. However, the corresponding forward modeling requires the simulation of a large-scale three-dimensional computational problem for each tool position. When the material properties are assumed...

article

A hybrid method for inversion of 3D AC resistivity logging measurements

Maciej Smołka, Ewa Gajda-Zagórska, Robert Schaefer, Maciej Paszyński, more

Applied Soft Computing > 2015 > 36 > C > 442-456

In this paper, we propose the use of a hybrid algorithm for the inversion of 3D Alternate Current (AC) resistivity logging measurements. The forward problem is solved using a goal-oriented self-adaptive hp-Finite Element Method (hp-FEM) that provides exponential convergence of the numerical error with respect to the mesh size. The inverse problem is solved using a Hierarchical Genetic Search (HGS)...

article

Direct solvers performance on h-adapted grids

Maciej Paszynski, David Pardo, Victor M. Calo

Computers and Mathematics with Applications > 2015 > 70 > 3 > 282-295

We analyse the performance of direct solvers when applied to a system of linear equations arising from an h-adapted, C0 finite element space. Theoretical estimates are derived for typical h-refinement patterns arising as a result of a point, edge, or face singularity as well as boundary layers. They are based on the elimination trees constructed specifically for the considered grids. Theoretical estimates...

article

Semi-analytical response of acoustic logging measurements in frequency domain

Ignacio Muga, David Pardo, Paweł J. Matuszyk, Carlos Torres-Verdín

Computers & Mathematics with Applications > 2015 > 70 > 4 > 314-329

This work proposes a semi-analytical method for simulation of the acoustic response of multipole eccentered sources in a fluid-filled borehole. Assuming a geometry that is invariant with respect to the azimuthal and vertical directions, the solution in frequency domain is expressed in terms of a Fourier series and a Fourier integral. The proposed semi-analytical method builds upon the idea of separating...

article

High-accuracy adaptive modeling of the energy distribution of a meniscus-shaped cell culture in a Petri dish

Ignacio Gomez-Revuelto, Luis E. Garcia-Castillo, David Pardo

Journal of Computational Science > 2015 > 9 > C > 143-149

Cylindrical Petri dishes embedded in a rectangular waveguide and exposed to a polarized electromagnetic wave are often used to grow cell cultures. To guarantee the success of these cultures, it is necessary to enforce that the specific absorption rate distribution is sufficiently high and uniform over the Petri dish. Accurate numerical simulations are needed to design such systems. These simulations...

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FINITE ELEMENT METHOD (14)
GOAL-ORIENTED ADAPTIVITY (5)
ERROR REPRESENTATION (4)
HP-ADAPTIVITY (4)
INVERSE PROBLEMS (4)
RECTANGULAR WAVEGUIDES (4)
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HP ADAPTIVE FINITE ELEMENT METHOD (3)
ISOGEOMETRIC ANALYSIS (3)
MEMETIC ALGORITHMS (3)
MULTI-FRONTAL DIRECT SOLVER (3)
MULTI-FRONTAL SOLVERS (3)
MULTI-PHYSICS PROBLEMS (3)
S-PARAMETERS (3)
ANISOTROPIC MESH ADAPTATION (2)
COLOR CORRECTION (2)
COMPUTATIONAL COMPLEXITY (2)
CONTRAST ENHANCEMENT (2)
DEADLOCK (2)
DEEP LEARNING (2)
DIRECT SOLVER (2)
ENERGY-NORM (2)
GOAL‐ORIENTED ADAPTIVITY (2)
GRAMMAR (2)
HELMHOLTZ EQUATION (2)
HIERARCHIC GENETIC STRATEGY (2)
HP-ADAPTIVE FINITE ELEMENT METHOD (2)
HYBRID METHOD (2)
HYPERMATRIX (2)
IMAGE DEHAZING (2)
INVERSE PROBLEM (2)
K-REFINEMENT (2)
MARINE CSEM (2)
MULTI-AGENT SYSTEMS (2)
MULTI-FRONTAL SOLVER (2)
MULTI-OBJECTIVE OPTIMIZATION METHODS (2)
P ADAPTIVITY (2)
PARALLEL COMPUTING (2)
PARALLEL DIRECT SOLVERS (2)
PETRI NET (2)
REFINED ISOGEOMETRIC ANALYSIS (RIGA) (2)
HP-ADAPTIVITY (1)
2.5D SIMULATIONS (1)
3D BOREHOLE RESISTIVITY (1)
3D DC BOREHOLE RESISTIVITY MEASUREMENT SIMULATIONS (1)
3D DC BOREHOLE RESISTIVITY MEASUREMENTS (1)
A PRIORI ADAPTATIVITY (1)
ACCOUSTICS OF THE HUMAN HEAD (1)
ADAPTIVE ALGORITHMS (1)
ADAPTIVE FINITE ELEMENT METHODS (1)
ARTIFICIAL LIGHTING (1)
ATMOSPHERIC MODELING (1)
ATTENUATION (1)
BIO COMPUTING (1)
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BOGOTÁ (1)
BOREHOLE (1)
BOREHOLE ACOUSTICS (1)
BOREHOLE MEASUREMENTS (1)
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CELL CULTURE (1)
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ECCENTRED (1)
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ELECTROMAGNETIC SIMULATIONS (1)
EMBODIED CONVERSATIONAL AGENTS (1)
ERROR ESTIMATION (1)
ERROR REPRESENTATION (1)
EXPONENTIAL INTEGRATORS (1)
FAST 2.5D SIMULATIONS (1)
FINITE ELEMENT ANALYSIS (FEA) (1)
FINITE ELEMENT METHOD (1)
FINITE ELEMENTS (1)
FLUORINE (1)
FORMATION EXPLORATION (1)
FORMATION RESISTIVITY MEASUREMENT (1)
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GEOPHYSICAL APPLICATIONS (1)
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Search results for: David Pardo

Semi‐blind‐trace algorithm for self‐supervised attenuation of trace‐wise coherent noise

Exploiting the Kronecker product structure of φ−functions in exponential integrators

Error control and loss functions for the deep learning inversion of borehole resistivity measurements

Clinical and neurophysiological characteristics of patients with Guillain‐Barré syndrome at Hospital Universitario San Ignacio, Bogotá, Colombia between 2009 and 2017

Forward‐in‐time goal‐oriented adaptivity

Fast 2.5D finite element simulations of borehole resistivity measurements

Goal‐oriented adaptivity using unconventional error representations for the multidimensional Helmholtz equation

Time-domain goal-oriented adaptivity using pseudo-dual error representations

The value of continuity: Refined isogeometric analysis and fast direct solvers

A multi-domain decomposition-based Fourier finite element method for the simulation of 3D marine CSEM measurements

A multi-objective memetic inverse solver reinforced by local optimization methods

Optimally refined isogeometric analysis

Goal-Oriented p-Adaptivity using Unconventional Error Representations for a 1D Steady State Convection-Diffusion Problem

A quadrature-free method for simulation and inversion of 1.5D direct current (DC) borehole measurements

Fusion-Based Variational Image Dehazing

A Priori Fourier Analysis for 2.5D Finite Elements Simulations of Logging-While-Drilling (LWD) Resistivity Measurements

A hybrid method for inversion of 3D AC resistivity logging measurements

Direct solvers performance on h-adapted grids

Semi-analytical response of acoustic logging measurements in frequency domain

High-accuracy adaptive modeling of the energy distribution of a meniscus-shaped cell culture in a Petri dish

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