Papers by Salvador García
Antenna Design and FDTD--Simulation: Theory and Measurement
Estudio comparativo de dos tratamientos cortos (7días) en la cicatriza- ción de la úlcera duodenal y erradicación de Helicobacter pylori Comparative study of two short treatments (7 days) in the cicatriza- tion of the duodenal ulcer and eradication of Helicobacter pylori
In this work, we describe the main features of IFS-CoCo, a coevolutionary method performing insta... more In this work, we describe the main features of IFS-CoCo, a coevolutionary method performing instance and feature selection for nearest neighbor classifiers. The coevolutionary model and several related background topics are revised, in order to present the method to the ICPR’10 contest “Classifier domains of competence: The Landscape contest”. The results obtained show that our proposal is a very competitive approach in the domains considered, outperforming both the benchmark results of the contest and the nearest neighbor rule.
International Conference on Next Generation Web Services Practices, 2011
Regarding information technologies, transnational education has to face several challenges in ord... more Regarding information technologies, transnational education has to face several challenges in order to offer a suitable education for computer science students worldwide. Software tools, and specially open source ones, give to the students the possibility of experiment with the most known techniques in the area. Among them, the KEEL software tool can be highlighted as a versatile framework for understanding the mechanics of several computational intelligence fields.
Quasi-static multi-domain inverse boundary element method for MRI coil design with minimum induced E-field
Engineering Analysis With Boundary Elements, 2011
Boundary element methods represent a valuable approach for designing MRI gradient coils. The temp... more Boundary element methods represent a valuable approach for designing MRI gradient coils. The temporally varying magnetic fields produced by gradient coils induce electric currents in conducting tissues and so the exposure of human subjects to these magnetic fields has become a safety concern, especially with the increase in the strength of the field gradients used in MRI. Here we extend the boundary element method presented in Cobos Sanchez et al. (2010) [4], for the design of coils that minimize the electric field induced in prescribed multi-compartment volume conductor made of different homogeneous sub-domains. The multi-domain E-coil method is illustrated with the design of cylindrical head gradient coils, whose performance is numerically compared to that produced by conventional coils and single domain E-coils.
The authors present the methodology used for collecting data developed through the use of the met... more The authors present the methodology used for collecting data developed through the use of the metaphor of dance. The tools were the workshops run in an Extension Course in Brazil given to nurses caring for women. The process is described as a meeting where the main objective reached was the collective construction of knowledge about the body of the women cared for. The socialization of experiences, the debate of ideas, the reflection about care permeated by solidarity and humanization, caring for the care-givers, reducing the asymmetry between researchers and researchedthe dancerswent beyond merely generating data towards research.
The experimental analysis on the performance of a proposed method is a crucial and necessary task... more The experimental analysis on the performance of a proposed method is a crucial and necessary task to carry out in a research. This paper is focused on the statistical analysis of the results in the community of Genetic Based Machine Learning.
Time domain simulation of THz photoconductive antennas
Proceedings of 6th European Conference on Antennas and Propagation, EuCAP 2012, 2012
ABSTRACT This paper presents a time-domain numerical method to analyze photoconductive antennas o... more ABSTRACT This paper presents a time-domain numerical method to analyze photoconductive antennas operating in the terahertz regime. Theoretical basis of the formulation relies on the combination of the solutions of Poisson's equation, carrier-transport equations, and Maxwell's equations. Numerical results, achieved by employing finite-difference schemes, agree with experimentally measured electromagnetic fields.
IEEE Microwave and Wireless Components Letters, 2012
Graphene-based devices constitute a pioneering field of research for their extraordinary electrom... more Graphene-based devices constitute a pioneering field of research for their extraordinary electromagnetic properties. The incorporation of appropriate models into numerical simulators is necessary in order to take advantage of these properties. In this work, we propose a method to incorporate graphene-sheet models into the FDTD method. The use of vector-fitting techniques expands the permittivity of graphene into a rational function series of complex conjugate pole-residue pairs, which is implemented into FDTD by an auxiliary differential equation formulation. Simple waveguiding problems validate our approach.
An FDTD thin-wire model for modeling carbon nanotube dipoles at THz regime
IEEE Antennas and Wireless Propagation Letters, 2012
ABSTRACT This letter presents an effective model for the numerical simulation of carbon nanotube ... more ABSTRACT This letter presents an effective model for the numerical simulation of carbon nanotube (CNT) antennas by finite-difference time domain (FDTD). The formulation is based on the classical Holland's thin-wire model, which includes the electromagnetic parameters of the CNT. Those parameters are derived by applying the electron-fluid model, acceptable up to the far-infrared regime. The results have been validated for both scattering and radiation problems, through a comparison of previously reported experimental measurements and numerical simulations based on integral equations.
IEEE Transactions on Microwave Theory and Techniques, 2012
The simulation of highly resonant structures requires techniques that are accurate and free of sp... more The simulation of highly resonant structures requires techniques that are accurate and free of spurious-mode contamination. Spurious modes can severely corrupt the solution of a physical problem, and their suppression is a must for any numerical scheme in the frequency or in the time domain (TD). In this paper, we present the application of a highly accurate spurious-free vector discontinuous Galerkin TD method to waveguide applications. We show that spurious solutions (which increase with the number of degrees of freedom of the problem) can be efficiently attenuated by using penalized fluxes. For validation, we apply our approach to the simulation of microwave filters since their highly resonant behavior is challenging for TD techniques. Since 2006, he has been with Cassidian, EADS-CASA, Getafe, Spain. His current research interests include computational electrodynamics in the TD, method of moments, and fast algorithms for integral equations in the FD, and computational electromagnetic applied to electromagnetic compatibility, antenna and RADAR cross-section problems.
HIRF Virtual Testing on the C-295 Aircraft: On the Application of a Pass/Fail Criterion and the FSV Method
IEEE Transactions on Electromagnetic Compatibility, 2013
Case study: GPR survey at the archaeological Roman site of Ciavieja, El Ejido (Spain)
Near Surface Geophysics, 2013
... Cóbos Sánchez, Mario Fernández Pantoja, Salvador González Garcıa, Amelia Rubio Bretones and R... more ... Cóbos Sánchez, Mario Fernández Pantoja, Salvador González Garcıa, Amelia Rubio Bretones and Rafael Gómez Martın Electromagnetism Group Electromagnetism and Physics Matter Department University of Granada Spain Email: cmdejong@ugr.es Ahmed Faize and ...
A Leap-Frog Discontinuous Galerkin Time-Domain Method for HIRF Assessment
IEEE Transactions on Electromagnetic Compatibility, 2013
ABSTRACT In this paper, we demonstrate the computational affordability and accuracy of a leap-fro... more ABSTRACT In this paper, we demonstrate the computational affordability and accuracy of a leap-frog discontinuous Galerkin (LFDG) time-domain method for high intensity radiated fields assessment in electromagnetic compatibility for aerospace. The conformal truncation of the computational domain is discussed and formulated in the LFDG context. Numerical validations are performed on challenging test cases, in comparison to measurements and to other numerical methods, demonstrating the accuracy, efficiency, and scalability of the algorithm.
Journal of Computational Physics, 2014
We introduce a novel local time-stepping technique for marching-in-time algorithms. The technique... more We introduce a novel local time-stepping technique for marching-in-time algorithms. The technique is denoted as Causal-Path Local Time-Stepping (CPLTS) and it is applied for two time integration techniques: fourth order low-storage explicit Runge-Kutta (LSERK4) and second order Leapfrog (LF2). The CPLTS method is applied to evolve Maxwell's curl equations using a Discontinuous Galerkin (DG) scheme for the spatial discretization.
Diamine Oxidase Activity During the Germinative and Post-Germinative Growth of the Embryonic Axis in Chickpea Seeds
Biologia Plantarum, 2002
Diamine oxidase (DAO, EC 1.4.3.6.), which participates in oxidative catabolism of polyamines (PAs... more Diamine oxidase (DAO, EC 1.4.3.6.), which participates in oxidative catabolism of polyamines (PAs), was not detected in the dry viable chickpea (Cicer arietinum L.) seeds. From the time when the embryonic axis acquired an aerobic metabolism, DAO increased concomitantly with the growth of the embryonic axis and at the same time with the deterioration of the cotyledons, although in these organs the values were clearly lower than in the axis. The highest DAO activity in the embryonic axis of seedlings grown for 72 and 96 h was found in the elongation, differentiation and hypocotyl zones, while the lowest was in the apex and plumule. The absence of cotyledons promoted the early appearance of DAO in the embryonic axis. When germination occurred at supraoptimal temperatures (30 – 35 °C), DAO activity was sharply inhibited both in the cotyledons and in the embryonic axis. This inhibition was accentuated further in the presence of cyclohexylamine, an inhibitor of spermidine synthase activity, to such a degree that DAO was undetectable in the cotyledons. DAO inhibition by EGTA and the pronounced reversal induced by Ca2+ implies that calcium may be related to DAO activity. The presence of putrescine, spermidine and spermine in the germination medium stimulated DAO activity, although this activity was inhibited when the exogenous PA was cadaverine.
This work describes the application of a hybrid time-domain technique that combines the Alternati... more This work describes the application of a hybrid time-domain technique that combines the Alternating Implicit Finite Difference Time Domain and the integral-equation-based Method of Moments in the Time Domain to analyze complex electromagnetic problems involving thin-wire antennas radiating in the presence of arbitrary inhomogeneous dielectric bodies. Examples of ultrawideband applications are shown.
Applied Numerical Mathematics, 1996
The use of (second-order) incremental unknowns to study the long-term dynamic behavior of nonline... more The use of (second-order) incremental unknowns to study the long-term dynamic behavior of nonlinear dissipative evolutionary equations when finite-difference approximations of such equations are considered was first proposed by ; in this work, we introduce higher-order incremental unknowns to perform such a study. We bring forward the basis which allows to recover these new incremental unknowns and we find out wavelet-like bases which are decomposed in two parts: the first part, constituted of large (significant) values, follows a well-ordered (linear) law; whereas, the second part, constituted of small (negligible) values, follows a chaotic law.
The matricial framework for the incremental unknowns method
Numerical Functional Analysis and Optimization, 1993
The Incremental Unknowns Method has first been introduced in [7] to study the long time integrati... more The Incremental Unknowns Method has first been introduced in [7] to study the long time integration of dissipative evolution equations when finite-difference approximations of such equations are used. The main object of this article is to further describe and study the algebraic framework of this new multigridlike method when several levels of discretization are considered.
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Papers by Salvador García