15 results on '"Cela, José María"'
Search Results
2. Optimization of atmospheric transport models on HPC platforms
- Author
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de la Cruz, Raúl, Folch, Arnau, Farré, Pau, Cabezas, Javier, Navarro, Nacho, and Cela, José María
- Published
- 2016
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3. Simulating archaeologists? Using agent-based modelling to improve battlefield excavations
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Rubio Campillo, Xavier, Cela, Jose María, and Hernàndez Cardona, Francesc Xavier
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- 2012
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4. Parallel 3-D marine controlled-source electromagnetic modelling using high-order tetrahedral Nédélec elements.
- Author
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Castillo-Reyes, Octavio, de la Puente, Josep, García-Castillo, Luis Emilio, and Cela, José María
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COMPUTATIONAL electromagnetics ,TETRAHEDRAL molecules ,MAXWELL equations ,PYTHON programming language ,HIGH performance computing - Abstract
We present a parallel and high-order Nédélec finite element solution for the marine controlled-source electromagnetic (CSEM) forward problem in 3-D media with isotropic conductivity. Our parallel Python code is implemented on unstructured tetrahedral meshes, which support multiple-scale structures and bathymetry for general marine 3-D CSEM modelling applications. Based on a primary/secondary field approach, we solve the diffusive form of Maxwell's equations in the low-frequency domain. We investigate the accuracy and performance advantages of our new high-order algorithm against a low-order implementation proposed in our previous work. The numerical precision of our high-order method has been successfully verified by comparisons against previously published results that are relevant in terms of scale and geological properties. A convergence study confirms that high-order polynomials offer a better trade-off between accuracy and computation time. However, the optimum choice of the polynomial order depends on both the input model and the required accuracy as revealed by our tests. Also, we extend our adaptive-meshing strategy to high-order tetrahedral elements. Using adapted meshes to both physical parameters and high-order schemes, we are able to achieve a significant reduction in computational cost without sacrificing accuracy in the modelling. Furthermore, we demonstrate the excellent performance and quasi-linear scaling of our implementation in a state-of-the-art high-performance computing architecture. [ABSTRACT FROM AUTHOR]
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- 2019
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5. D8.1.2: Performance Model of Community Codes
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Gheller, Claudio, Sawyer, Will, Schulthess, Thomas, Affinito, Fabio, Girotto, Ivan, McKinstry, Alastair, Spiga, Filippo, Crouzet, Laurent, Sunderland, Andy, Koutsou, Giannis, Abdel-Rehim, Abdou, Nogueira, Fernando, Avillez, Miguel, Huhs, Georg, Cela, José María, and Jowkar, Mohammad
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Deliverable ,Scientific applications ,HPC ,Libraries ,Research infrastructure ,Performance modelling - Abstract
This document presents the results achieved by PRACE-2IP Work Package 8 at PM3. Scientific communities, selected during the first project month, proposed a number of codes relevant for the scientific domain and promising in terms of potential performance improvement on the coming generation of supercomputing architectures. In order to analyse the performance features of these codes, a methodology, based on the performance modelling approach, has been defined and adopted. This methodology relies on the analytic modelling of the main algorithms (characterising the dependency from the critical model parameters) and on the performance analysis, based on the usage of performance tools. The performance modelling approach allows studying the current behaviour of a code, emphasising performance and bottlenecks. But it is also a predictive tool, allowing the estimation of the code’s behaviour on different computing architectures, and identifying the most promising areas for performance improvement. The first step of the modelling is represented by performance analysis. This analysis was accomplished for all the proposed codes, with detailed data generated and collected. The overall results are presented for each scientific domain and code. Most of the data was generated for “real cases”, i.e., running the codes for real scientifically meaningful cases, in order to evaluate performances and bottlenecks in daily usage configurations, and to achieve a performance impact through code refactoring and optimisation of the crucial sections of each code. In the following step of WP8, this data will be synthesised and modelled, in order to identify the most promising numerical kernels for performance improvement. This will be the subject of the coming deliverable D8.1.3 “Prototype Codes Exploring Performance Improvements”.
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- 2011
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6. Elastic Full Waveform Inversion (FWI) of Reflection Data with a Phase Misfit Function.
- Author
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Kormann, Jean, Rodríguez, Juan Esteban, Ferrer, Miguel, Gutiérrez, Natalia, de la Puente, Josep, Hanzich, Mauricio, and Cela, José María
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- 2016
- Full Text
- View/download PDF
7. Unveiling WARIS Code, a Parallel and Multi-purpose FDM Framework.
- Author
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de la Cruz, Raúl, Hanzich, Mauricio, Folch, Arnau, Houzeaux, Guillaume, and Cela, José María
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- 2015
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8. A review of block Krylov subspace methods for multisource electromagnetic modelling.
- Author
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Puzyrev, Vladimir and Cela, José María
- Subjects
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KRYLOV subspace , *SUBSPACES (Mathematics) , *LINEAR systems , *FINITE element method , *MATHEMATICAL models - Abstract
Practical applications of controlled-source electromagnetic (EM) modelling require solutions for multiple sources at several frequencies, thus leading to a dramatic increase of the computational cost. In this paper, we present an approach using block Krylov subspace solvers that are iterative methods especially designed for problems with multiple right-hand sides (RHS). Their main advantage is the shared subspace for approximate solutions, hence, these methods are expected to converge in less iterations than the corresponding standard solver applied to each linear system. Block solvers also share the same preconditioner, which is constructed only once. Simultaneously computed block operations have better utilization of cache due to the less frequent access to the system matrix. In this paper, we implement two different block solvers for sparse matrices resulting from the finite-difference and the finite-element discretizations, discuss the computational cost of the algorithms and study their dependence on the number of RHS given at once. The effectiveness of the proposed methods is demonstrated on two EMsurvey scenarios, including a large marine model. As the results of the simulations show, when a powerful preconditioning is employed, block methods are faster than standard iterative techniques in terms of both iterations and time. [ABSTRACT FROM AUTHOR]
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- 2015
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9. Introducing the Semi-stencil Algorithm.
- Author
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de la Cruz, Raúl, Araya-Polo, Mauricio, and Cela, José María
- Abstract
Finite Difference (FD) is a widely used method to solve Partial Differential Equations (PDE). PDEs are the core of many simulations in different scientific fields, e.g. geophysics, astrophysics, etc. The typical FD solver performs stencil computations for the entire 3D domain, thus solving the differential operator. This computation consists on accumulating the contribution of the neighbor points along the cartesian axis. It is performance-bound by two main problems: the memory access pattern and the inefficient re-utilization of the data. We propose a novel algorithm, named ″semi-stencil″, that tackle those two problems. Our first target architecture for testing is Cell/B.E., where the implementation reaches 12.4 GFlops (49% peak performance) per SPE, while the classical stencil computation only reaches 34%. Further, we successfully apply this code optimization to an industrial-strength application (Reverse-Time Migration). These results show that semi-stencil is useful stencil computation optimization. [ABSTRACT FROM AUTHOR]
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- 2010
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10. Alya: Multiphysics engineering simulation toward exascale.
- Author
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Vázquez, Mariano, Houzeaux, Guillaume, Koric, Seid, Artigues, Antoni, Aguado-Sierra, Jazmin, Arís, Ruth, Mira, Daniel, Calmet, Hadrien, Cucchietti, Fernando, Owen, Herbert, Taha, Ahmed, Burness, Evan Dering, Cela, José María, and Valero, Mateo
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PHYSICS ,COMPUTER simulation ,HIGH performance computing ,COMPUTER programming ,COMPUTER algorithms ,COMPUTATIONAL physics - Abstract
Alya is a multi-physics simulation code developed at Barcelona Supercomputing Center (BSC). From its inception Alya code is designed using advanced High Performance Computing programming techniques to solve coupled problems on supercomputers efficiently. The target domain is engineering, with all its particular features: complex geometries and unstructured meshes, coupled multi-physics with exotic coupling schemes and physical models, ill-posed problems, flexibility needs for rapidly including new models, etc. Since its beginnings in 2004, Alya has scaled well in an increasing number of processors when solving single-physics problems such as fluid mechanics, solid mechanics, acoustics, etc. Over time, we have made a concerted effort to maintain and even improve scalability for multi-physics problems. This poses challenges on multiple fronts, including: numerical models, parallel implementation, physical coupling models, algorithms and solution schemes, meshing process, etc. In this paper, we introduce Alya's main features and focus particularly on its solvers. We present Alya's performance up to 100.000 processors in Blue Waters, the NCSA supercomputer with selected multi-physics tests that are representative of the engineering world. The tests are incompressible flow in a human respiratory system, low Mach combustion problem in a kiln furnace, and coupled electro-mechanical contraction of the heart. We show scalability plots for all cases and discuss all aspects of such simulations, including solver convergence. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
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11. Algebraic multigrid preconditioning within parallel finite-element solvers for 3-D electromagnetic modelling problems in geophysics.
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Koldan, Jelena, Puzyrev, Vladimir, de la Puente, Josep, Houzeaux, Guillaume, and Cela, José María
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ELECTROMAGNETIC fields ,GEOPHYSICAL prospecting ,ALGEBRAIC multigrid methods ,ITERATIVE methods (Mathematics) ,MATHEMATICAL models ,FINITE element method - Abstract
We present an elaborate preconditioning scheme for Krylov subspace methods which has been developed to improve the performance and reduce the execution time of parallel node-based finite-element (FE) solvers for 3-D electromagnetic (EM) numerical modelling in exploration geophysics. This new preconditioner is based on algebraic multigrid (AMG) that uses different basic relaxation methods, such as Jacobi, symmetric successive over-relaxation (SSOR) and Gauss–Seidel, as smoothers and the wave front algorithm to create groups, which are used for a coarse-level generation. We have implemented and tested this new preconditioner within our parallel nodal FE solver for 3-D forward problems in EM induction geophysics. We have performed series of experiments for several models with different conductivity structures and characteristics to test the performance of our AMG preconditioning technique when combined with biconjugate gradient stabilized method. The results have shown that, the more challenging the problem is in terms of conductivity contrasts, ratio between the sizes of grid elements and/or frequency, the more benefit is obtained by using this preconditioner. Compared to other preconditioning schemes, such as diagonal, SSOR and truncated approximate inverse, the AMG preconditioner greatly improves the convergence of the iterative solver for all tested models. Also, when it comes to cases in which other preconditioners succeed to converge to a desired precision, AMG is able to considerably reduce the total execution time of the forward-problem code—up to an order of magnitude. Furthermore, the tests have confirmed that our AMG scheme ensures grid-independent rate of convergence, as well as improvement in convergence regardless of how big local mesh refinements are. In addition, AMG is designed to be a black-box preconditioner, which makes it easy to use and combine with different iterative methods. Finally, it has proved to be very practical and efficient in the parallel context. [ABSTRACT FROM PUBLISHER]
- Published
- 2014
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12. HPC Geophysical Electromagnetics: A Synthetic VTI Model with Complex Bathymetry.
- Author
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Castillo-Reyes, Octavio, de la Puente, Josep, and Cela, José María
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HYDROCARBON reservoirs ,ELECTROMAGNETIC measurements ,COMPUTATIONAL electromagnetics ,BATHYMETRY ,ELECTROMAGNETISM ,HYDROGRAPHIC surveying - Abstract
We introduce a new synthetic marine model for 3D controlled-source electromagnetic method (CSEM) surveys. The proposed model includes relevant features for the electromagnetic geophysical community such as large conductivity contrast with vertical transverse isotropy and a complex bathymetry profile. In this paper, we present the experimental setup and several 3D CSEM simulations in the presence of a resistivity unit denoting a hydrocarbon reservoir. We employ a parallel and high-order vector finite element routine to perform the CSEM simulations. By using tailored meshes, several scenarios are simulated to assess the influence of the reservoir unit presence on the electromagnetic responses. Our numerical assessment confirms that resistivity unit strongly influences the amplitude and phase of the electromagnetic measurements. We investigate the code performance for the solution of fundamental frequencies on high-performance computing architectures. Here, excellent performance ratios are obtained. Our benchmark model and its modeling results are developed under an open-source scheme that promotes easy access to data and reproducible solutions. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
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13. A parallel finite-element method for three-dimensional controlled-source electromagnetic forward modelling.
- Author
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Puzyrev, Vladimir, Koldan, Jelena, de la Puente, Josep, Houzeaux, Guillaume, Vázquez, Mariano, and Cela, José María
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ELECTROMAGNETIC theory ,FINITE element method ,ELECTROMAGNETIC fields ,APPROXIMATION theory ,MAXWELL equations - Abstract
We present a nodal finite-element method that can be used to compute in parallel highly accurate solutions for 3-D controlled-source electromagnetic forward-modelling problems in anisotropic media. Secondary coupled-potential formulation of Maxwell's equations allows to avoid the singularities introduced by the sources, while completely unstructured tetrahedral meshes and mesh refinement support an accurate representation of geological and bathymetric complexity and improve the solution accuracy. Different complex iterative solvers and an efficient pre-conditioner based on the sparse approximate inverse are used for solving the resulting large sparse linear system of equations. Results are compared with the ones of other researchers to check the accuracy of the method. We demonstrate the performance of the code in large problems with tens and even hundreds of millions of degrees of freedom. Scalability tests on massively parallel computers show that our code is highly scalable. [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
- View/download PDF
14. 3D seismic imaging through reverse-time migration on homogeneous and heterogeneous multi-core processors.
- Author
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Araya-Polo, Mauricio, Rubio, Félix, Dela Cruz, Raúl, Hanzich, Mauricio, Cela, José María, and Scarpazza, Daniele Paolo
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MULTICORE processors ,ACOUSTIC imaging ,PETROLEUM industry ,GAS well drilling ,ARCHITECTURE ,BANDWIDTHS - Abstract
Reverse-Time Migration (RTM) is a state-of-the-art technique in seismic acoustic imaging, because of the quality and integrity of the images it provides. Oil and gas companies trust RTM with crucial decisions on multi-million-dollar drilling investments. But RTM requires vastly more computational power than its predecessor techniques, and this has somewhat hindered its practical success. On the other hand, despite multi-core architectures promise to deliver unprecedented computational power, little attention has been devoted to mapping efficiently RTM to multi-cores. In this paper, we present a mapping of the RTM computational kernel to the IBM Cell/B.E. processor that reaches close-to-optimal performance. The kernel proves to be memory-bound and it achieves a 98% utilization of the peak memory bandwidth. Our Cell/B.E. implementation outperforms a traditional processor (PowerPC 970MP) in terms of performance (with an 15.0× speedup) and energy-efficiency (with a 10.0× increase in the GFlops/W delivered). Also, it is the fastest RTM implementation available to the best of our knowledge. These results increase the practical usability of RTM. Also, the RTM-Cell/B.E. combination proves to be a strong competitor in the seismic arena. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
15. Real-space density functional theory and time dependent density functional theory using finite/infinite element methods
- Author
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Soba, Alejandro, Bea, Edgar Alejandro, Houzeaux, Guillaume, Calmet, Hadrien, and Cela, José María
- Subjects
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DENSITY functionals , *FINITE element method , *NUMERICAL analysis , *ELECTRONIC structure , *HARTREE-Fock approximation , *PARALLEL computers , *POLYNOMIALS , *MATHEMATICAL models - Abstract
Abstract: We present a numerical approach using the finite element method to discretize the equations that allow getting a first-principles description of multi-electronic systems within DFT and TD-DFT formalisms. A strictly local polynomial function basis set is used in order to represent the entire real-space domain. Infinite elements are introduced to model the infinite external boundaries in the case of Hartree’s equation. The diagonal mass matrix is obtained using a close integration rule, reducing the generalized eigenvalue problem to a standard one. This framework of electronic structure calculation is embedded in a high performance computing environment with a very good parallel behavior. [Copyright &y& Elsevier]
- Published
- 2012
- Full Text
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