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1. Exploring the operational limits of Mirnov coil arrays in stellarators by means of a synthetic diagnostic

Author

Pons-Villalonga, Pedro, Cappa, Álvaro, and Martínez-Fernández, José

Subjects
Physics - Plasma Physics
Abstract

A synthetic Mirnov coils diagnostic is presented and used to study the capabilities of the poloidal array of single-axis coils and the two helical arrays of tri-axial coils installed in the TJ-II stellarator. This tool integrates the plasma currents induced by Alfv\'en-like perturbations of the electric potential inside the plasma and provides the induced magnetic field oscillations anywhere outside of it. The simulated signals can then be analyzed in the same manner as the experimental ones, and a scan on the radial position and width of the potential perturbation is conducted to find the limiting values that produce identifiable signals. We find, not surprisingly, that core-localized modes are indistinguishable from one another; and that the identification of low-n, low-m modes is often subject to off-by-one errors. We also determine the optimal polarization basis in which to analyze the tri-axial coils signals and address the diagnostic performance when resolving components of gap modes such as HAEs. Additionally, selected cases have been analyzed with a simplified plasma response model, showing that plasma shielding of the mode currents may further deteriorate the accuracy of the mode identification method. We conclude with the analysis of an experimental case taken from the TJ-II database to illustrate the usefulness of the diagnostic. The code for this synthetic diagnostic, that can be easily used to conduct similar analysis for other devices, is publicly available in http://github.com/pponsv/synth_mirnov .

Published
2024

2. Validating neutral-beam current drive simulations in the TJ-II stellarator

Author

Mulas, Sadig, Cappa, Álvaro, Martínez-Fernández, José, López-Bruna, Daniel, Velasco, José Luis, Estrada, Teresa, Gómez-Manchón, Jesús Manuel, Liniers, Macarena, Pastor, Ignacio, Medina, Francisco, Ascasíbar, Enrique, and Team, TJ-II

Subjects
Physics - Plasma Physics
Abstract

In this paper, we analyze the results of neutral-beam current drive (NBCD) experiments, performed in the TJ-II stellarator, with the aim of validating the theoretical predictions. Both parallel and anti-parallel injection with respect to the magnetic field were explored using co (NBI1) and counter (NBI2) beams at different injected beam power and plasma densities. The fast-ion current driven by both beams was simulated with the Monte Carlo code ASCOT and the electron response to the fast-ion current was calculated analytically using a model valid for an arbitrary magnetic configuration and a low collisionality plasma. The model reproduces with rather good agreement the toroidal current measured in NBI2 plasmas while the current driven by NBI1 is less than half the predicted one. Possible reasons for this discrepancy are discussed.

Published
2023
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9. EL SISTEMA DE FINANCIACIÓN DE LAS DIPUTACIONES PROVINCIALES Y SU EFECTO NEGATIVO EN CASTILLA Y LEÓN.

Author

Martínez Fernández, José Manuel

Subjects
LOCAL finance, INCOME, INTERNAL revenue, STATE taxation, ENERGY tax
Abstract

Copyright of Revista Jurídica de Castilla y León is the property of Junta de Castilla y Leon, Direccion de Servicios Juridicos and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Published
2025

11. COVID-19 in transplant recipients: The Spanish experience

Author

Coll, Elisabeth, Fernández-Ruiz, Mario, Sánchez-Álvarez, J. Emilio, Martínez-Fernández, José R., Crespo, Marta, Gayoso, Jorge, Bada-Bosch, Teresa, Oppenheimer, Federico, Moreso, Francesc, López-Oliva, María O., Melilli, Edoardo, Rodríguez-Ferrero, Marisa L., Bravo, Carlos, Burgos, Elena, Facundo, Carme, Lorenzo, Inmaculada, Yañez, Íñigo, Galeano, Cristina, Roca, Ana, Cabello, Mercedes, Gómez-Bueno, Manuel, García-Cosío, M<ce:sup loc='post">a</ce:sup>Dolores, Graus, Javier, Lladó, Laura, de Pablo, Alicia, Loinaz, Carmelo, Aguado, Beatriz, Hernández, Domingo, and Domínguez-Gil, Beatriz

Published
2021
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17. The many faces of the Liar Paradox

Author

Martínez Fernández, José, Oms, Sergi, Martínez Fernández, José, and Oms, Sergi

Abstract

The Liar Paradox is a classic argument that creates a contradiction by reflection on a sentence that attributes falsity to itself: ‘this sentence is false’. In our paper we will discuss the ways in which the Liar sentence (and its paradoxical argument) can be represented in first-order logic. The key to the representation is to use first-order logic to model a self-referential language. We will also discuss several related sentences, like the Liar cycles, the empirical versions of the Liar and the Truth teller sentences.

Published
2024

20. Buenas Prácticas en la Atención a Familiares y Allegados en Casos de Desaparición de Personas. La Importancia del Profesional de la Psicología Especializado en Desapariciones.

Author

Isabel Álvarez-Aparicio, Ana, Martínez Fernández, José María, Acinas Acinas, María Patricia, and Herráez-Collado, Elena

Subjects
*MISSING persons, *PSYCHOTHERAPY, *BEST practices, *RELATIVES, *DATABASES
Abstract

Each year, an average of 23,000 missing persons reports are filed in Spain. Although most of them are resolved in the first few days, a significant number of people remain in the databases for years. The impact of a disappearance at all levels is not limited to the missing person's immediate environment but extends to different groups-professionals, community, and society-with a particular impact on family members and relatives. Best practices in the assistance provided to the latter are crucial due to the associated benefits. The role of the psychology professional, specialized in disappearances, is essential in the areas of prevention, intervention, and postvention. [ABSTRACT FROM AUTHOR]

Published
2024
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24. Introduction

Author

Achourioti, Theodora, Fujimoto, Kentaro, Galinon, Henri, Martínez-Fernández, José, Rahman, Shahid, Series editor, Symons, John, Series editor, Achourioti, Theodora, editor, Galinon, Henri, editor, Martínez Fernández, José, editor, and Fujimoto, Kentaro, editor

Published
2015
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25. Assessment of the SMAP Level-4 Surface and Root-Zone Soil Moisture Product Using In Situ Measurements

Author

Reichle, Rolf H., De Lannoy, Gabrielle J. M., Liu, Qing, Ardizzone, Joseph V., Colliander, Andreas, Conaty, Austin, Crow, Wade, Jackson, Thomas J., Jones, Lucas A., Kimball, John S., Koster, Randal D., Mahanama, Sarith P., Smith, Edmond B., Berg, Aaron, Bircher, Simone, Bosch, David, Caldwell, Todd G., Cosh, Michael, González-Zamora, Ángel, Collins, Chandra D. Holifield, Jensen, Karsten H., Livingston, Stan, Lopez-Baeza, Ernesto, Martínez-Fernández, José, McNairn, Heather, Moghaddam, Mahta, Pacheco, Anna, Pellarin, Thierry, Prueger, John, Rowlandson, Tracy, Seyfried, Mark, Starks, Patrick, Su, Zhongbo, Thibeault, Marc, Van Der Velde, Rogier, Walker, Jeffrey, Wu, Xiaoling, and Zeng, Yijian

Published
2017

28. On the Variability in the Temporal Stability Pattern of Soil Moisture Under Mediterranean Conditions.

Author

González-Zamora, Ángel, Benito-Verdugo, Pilar, and Martínez-Fernández, José

Subjects
SOIL moisture, SOIL moisture measurement, SOIL dynamics, SPATIAL variation
Abstract

In recent decades, there has been increasing interest in studying the variability in soil water properties and, specifically, the spatiotemporal variability in the soil water content. This is motivated by the notable theoretical and applied research interests in soil moisture dynamics and their implications for many natural processes. This study aimed to study whether there are variations in the spatial pattern of the temporal stability of soil moisture over time and to analyze the possible influences of certain hydroclimatic (soil water content, precipitation, and evapotranspiration) and soil factors (texture, bulk density, and organic matter content) on these variations. This study was conducted within the Soil Moisture Measurement Stations Network of the University of Salamanca (REMEDHUS, Spain) under Mediterranean conditions, with daily surface moisture data (0-5 cm depth) obtained from 20 stations for the 2006-2023 period. The results showed differences between the average pattern obtained with the 18-year data series and that obtained with the data series for each year. In more than half of the years studied, the representative station differed from that derived from the average pattern. The mean annual precipitation and summer precipitation characteristics seem to be the main factors influencing the variability in the spatial pattern of the temporal stability of soil moisture. [ABSTRACT FROM AUTHOR]

Published
2024
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30. Introduction

Author

Martí, Genoveva and Martínez-Fernández, José

Published
2017

33. Shedding light on the metal-phthalocyanine EXAFS spectra through classical and ab initio molecular dynamics

Author

Universidad de Sevilla. Departamento de Química Física, Ministerio de Ciencia e Innovación (MICIN). España, Agencia Estatal de Investigación. España, European Commission (EC). Fondo Europeo de Desarrollo Regional (FEDER), Junta de Andalucía, Universidad de Sevilla, Raposo Hernández, Gema, Sánchez Marcos, Enrique, Rodríguez Pappalardo, Rafael, Martínez Fernández, José Manuel, Universidad de Sevilla. Departamento de Química Física, Ministerio de Ciencia e Innovación (MICIN). España, Agencia Estatal de Investigación. España, European Commission (EC). Fondo Europeo de Desarrollo Regional (FEDER), Junta de Andalucía, Universidad de Sevilla, Raposo Hernández, Gema, Sánchez Marcos, Enrique, Rodríguez Pappalardo, Rafael, and Martínez Fernández, José Manuel

Abstract

Extended X-Ray Absorption Fine Structure (EXAFS) theoretical spectra for some 3d transition metal-phthalocyanines–FePc, NiPc, CuPc, and ZnPc-are presented. Their complexity and rigidity make them a good testbed for the development of theoretical strategies that can complement the difficulties present in the experimental spectrum fitting. Classical and ab initio molecular dynamics trajectories are generated and employed as a source of structural information to compute average spectra for each MPc species. The original ZnPc force field employed in the classical molecular dynamics simulations has been modified in order to improve the agreement with the experimental EXAFS spectrum, and the modification strategy–based on MP2 optimized structures–being extended to the rest of MPcs. Both types of trajectories, classical and ab initio, provide very similar results, showing in all cases the main features present in the experimental spectra despite the different simulation timescales employed. Spectroscopical information has been analyzed on the basis of shells and legs contributions, making possible the comparison with the experimental fitting approaches. According to the simulations results, the simple relationships employed in the fitting process to define the dependence of the Debye Waller factors associated with multiple scattering paths with those of single scattering paths are reasonable. However, a lack of multiple backscattering paths contributions is found due to the intrinsic rigidity of the chemical motif (macrocycle). Its consequences in the Debye Waller factors of the fitted contributions are discussed.

Published
2023

34. Patrones de aprendizaje, factores socio-familiares, memoria y rendimiento académico en jóvenes tutelados

Author

Vega Martínez, Antonio, Martínez Pons, Marc, Martínez Fernández, José Reinaldo, Vega Martínez, Antonio, Martínez Pons, Marc, and Martínez Fernández, José Reinaldo

Abstract

This study attempts to identify the factors that influence the learning process of tutored young people. It investigates the relationship between learning patterns, socio-family factors, short-term verbal memory and academic performance of minors tutored by the Gen-eral Directorate of Attention to Children and Adolescents (DGAIA). The sample is made up of 32 subjects between the ages of 13 and 15, who live in Residential Centres for Educational Action in Catalonia. The instruments used were: The Inventory of Learning Patterns, Atkinson and Shiffrin’s memory test and a Questionnaire of socio-family aspects, which also includes two performance questions (repetition and average grade). The results show a relationship between the considered variables, so that the subjects with learning patterns associated with better academic performance, such as meaning-directed and application-directed, are related to favourable psychosocial factors and high short-term verbal memory. The reproduction-directed and undirected patterns are associated with poor academic performance, unfavourable psychosocial factors, and low short-term verbal memory., Esta investigação visa identificar os factores que influenciam o processo de apren-dizagem dos jovens em cuidados de saúde. Investiga-se a relação entre padrões de aprendizagem, factores sócio-familiares, memória verbal de curto prazo e desempenho académico dos menores que estão sob os cuidados da Direcção Geral de Cuidados à Criança e ao Adolescente (DGAIA). A amostra consistiu em 32 participantes com idades compreendidas entre os 13 e os 15 anos, residentes em Centros Residenciais de Acção Educativa na Catalunha. Os instrumentos utilizados foram: o Inventário de Padrões de Aprendizagem, o teste de memória Atkinson e Shiffrin e um questionário sobre aspectos sócio-familiares, que incluiu também duas perguntas sobre o desempenho (repetição e nota média). Os resultados mostram uma relação entre as variáveis estudadas, de modo que as pessoas com padrões de aprendizagem associados a um melhor desempenho académico, tais como o orientado para o significado e o orientado para a aplicação, estão relacionados com factores sócio-familiares favoráveis e uma elevada memória verbal a curto prazo. Os padrões dirigidos e não dirigidos à reprodução estão associados a um fraco desempenho académico, a factores sócio-familiares desfavoráveis e a uma baixa memória verbal de curto prazo., La presente investigación trata de identificar los factores que influyen en el pro-ceso de aprendizaje de personas jóvenes tuteladas. Se investiga sobre la relación entre los patrones de aprendizaje, los factores socio-familiares, la memoria verbal a corto plazo y el rendimiento académico de menores que están bajo la tutela de la Dirección General de Atención a la Infancia y Adolescencia (DGAIA). La muestra está compuesta por 32 participantes con edades comprendidas entre los 13 y 15 años, que conviven en Centros Residenciales de Acción Educativa en Cataluña. Los instrumentos utilizados fueron: el Inventory of Learning Patterns, Prueba de memoria de Atkinson y Shiffrin y un Cuestionario de aspectos socio-familiares en el cual, también, se incluye dos preguntas sobre el rendimiento (repitencia y nota media). Los resultados muestran relación entre las variables estudiadas, de modo que las personas con patrones de aprendizaje asociados a un mejor rendimiento académico, como son el dirigido al significado y dirigido a la aplicación, se relacionan con factores socio-familiares favorables y memoria verbal a corto plazo alta. Los patrones, dirigido a la reproducción y no dirigido, se asocian con un rendimiento académico insuficiente, con factores socio-familiares no favorables y memoria verbal a corto plazo baja

Published
2023

36. Multimodal Queries to Access Multimedia Information Sources: First Steps

Author

Martínez, Ángel, Lana Serrano, Sara, Martínez-Fernández, José L., Martínez, Paloma, Akan, Ozgur, Series editor, Bellavista, Paolo, Series editor, Cao, Jiannong, Series editor, Dressler, Falko, Series editor, Ferrari, Domenico, Series editor, Gerla, Mario, Series editor, Kobayashi, Hisashi, Series editor, Palazzo, Sergio, Series editor, Sahni, Sartaj, Series editor, Shen, Xuemin (Sherman), Series editor, Stan, Mircea, Series editor, Xiaohua, Jia, Series editor, Zomaya, Albert, Series editor, Coulson, Geoffrey, Series editor, Alvarez, Federico, editor, and Costa, Cristina, editor

Published
2012
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37. Some Experiments in Evaluating ASR Systems Applied to Multimedia Retrieval

Author

Moreno, Julián, Garrote, Marta, Martínez, Paloma, Martínez-Fernández, José L., Hutchison, David, Series editor, Kanade, Takeo, Series editor, Kittler, Josef, Series editor, Kleinberg, Jon M., Series editor, Mattern, Friedemann, Series editor, Mitchell, John C., Series editor, Naor, Moni, Series editor, Nierstrasz, Oscar, Series editor, Pandu Rangan, C., Series editor, Steffen, Bernhard, Series editor, Sudan, Madhu, Series editor, Terzopoulos, Demetri, Series editor, Tygar, Doug, Series editor, Vardi, Moshe Y., Series editor, Weikum, Gerhard, Series editor, Detyniecki, Marcin, editor, García-Serrano, Ana, editor, and Nürnberger, Andreas, editor

Published
2011
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38. Rainfall estimation from in situ soil moisture observations at several sites in Europe: an evaluation of the SM2RAIN algorithm

Author

Brocca Luca, Massari Christian, Ciabatta Luca, Moramarco Tommaso, Penna Daniele, Zuecco Giulia, Pianezzola Luisa, Borga Marco, Matgen Patrick, and Martínez-Fernández José

Subjects
rainfall, soil moisture, in situ observations, experimental sites, sm2rain., Hydraulic engineering, TC1-978
Abstract

Rain gauges, weather radars, satellite sensors and modelled data from weather centres are used operationally for estimating the spatial-temporal variability of rainfall. However, the associated uncertainties can be very high, especially in poorly equipped regions of the world. Very recently, an innovative method, named SM2RAIN, that uses soil moisture observations to infer rainfall, has been proposed by Brocca et al. (2013) with very promising results when applied with in situ and satellite-derived data. However, a thorough analysis of the physical consistency of the SM2RAIN algorithm has not been carried out yet. In this study, synthetic soil moisture data generated from a physically-based soil water balance model are employed to check the reliability of the assumptions made in the SM2RAIN algorithm. Next, high quality and multiyear in situ soil moisture observations, at different depths (5-30 cm), and rainfall for ten sites across Europe are used for testing the performance of the algorithm, its limitations and applicability range.

Published
2015
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41. Towards an Improvement of Software Development Processes through Standard Business Rules

Author

Martínez-Fernández, José L., Martínez, Paloma, González-Cristóbal, José C., Hutchison, David, editor, Kanade, Takeo, editor, Kittler, Josef, editor, Kleinberg, Jon M., editor, Mattern, Friedemann, editor, Mitchell, John C., editor, Naor, Moni, editor, Nierstrasz, Oscar, editor, Pandu Rangan, C., editor, Steffen, Bernhard, editor, Sudan, Madhu, editor, Terzopoulos, Demetri, editor, Tygar, Doug, editor, Vardi, Moshe Y., editor, Weikum, Gerhard, editor, Governatori, Guido, editor, Hall, John, editor, and Paschke, Adrian, editor

Published
2009
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42. The MIRACLE Team at the CLEF 2008 Multilingual Question Answering Track

Author

Martínez-González, Ángel, de Pablo-Sánchez, César, Polo-Bayo, Concepción, Vicente-Díez, María Teresa, Martínez-Fernández, Paloma, Martínez-Fernández, José Luís, Hutchison, David, Series editor, Kanade, Takeo, Series editor, Kittler, Josef, Series editor, Kleinberg, Jon M., Series editor, Mattern, Friedemann, Series editor, Mitchell, John C., Series editor, Naor, Moni, Series editor, Nierstrasz, Oscar, Series editor, Pandu Rangan, C., Series editor, Steffen, Bernhard, Series editor, Sudan, Madhu, Series editor, Terzopoulos, Demetri, Series editor, Tygar, Doug, Series editor, Vardi, Moshe Y., Series editor, Weikum, Gerhard, Series editor, Peters, Carol, editor, Deselaers, Thomas, editor, Ferro, Nicola, editor, Gonzalo, Julio, editor, Jones, Gareth J. F., editor, Kurimo, Mikko, editor, Mandl, Thomas, editor, Peñas, Anselmo, editor, and Petras, Vivien, editor

Published
2009
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43. A Preliminary Approach to the Automatic Extraction of Business Rules from Unrestricted Text in the Banking Industry

Author

Martínez-Fernández, José L., González, José C., Villena, Julio, Martínez, Paloma, Hutchison, David, editor, Kanade, Takeo, editor, Kittler, Josef, editor, Kleinberg, Jon M., editor, Mattern, Friedemann, editor, Mitchell, John C., editor, Naor, Moni, editor, Nierstrasz, Oscar, editor, Pandu Rangan, C., editor, Steffen, Bernhard, editor, Sudan, Madhu, editor, Terzopoulos, Demetri, editor, Tygar, Doug, editor, Vardi, Moshe Y., editor, Weikum, Gerhard, editor, Kapetanios, Epaminondas, editor, Sugumaran, Vijayan, editor, and Spiliopoulou, Myra, editor

Published
2008
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44. MIRACLE at ImageCLEFphoto 2007: Evaluation of Merging Strategies for Multilingual and Multimedia Information Retrieval

Author

Villena-Román, Julio, Lana-Serrano, Sara, Martínez-Fernández, José Luis, González-Cristóbal, José Carlos, Hutchison, David, editor, Kanade, Takeo, editor, Kittler, Josef, editor, Kleinberg, Jon M., editor, Mattern, Friedemann, editor, Mitchell, John C., editor, Naor, Moni, editor, Nierstrasz, Oscar, editor, Pandu Rangan, C., editor, Steffen, Bernhard, editor, Sudan, Madhu, editor, Terzopoulos, Demetri, editor, Tygar, Doug, editor, Vardi, Moshe Y., editor, Weikum, Gerhard, editor, Peters, Carol, editor, Jijkoun, Valentin, editor, Mandl, Thomas, editor, Müller, Henning, editor, Oard, Douglas W., editor, Peñas, Anselmo, editor, Petras, Vivien, editor, and Santos, Diana, editor

Published
2008
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45. Combining Wikipedia and Newswire Texts for Question Answering in Spanish

Author

de Pablo-Sánchez, César, Martínez-Fernández, José L., González-Ledesma, Ana, Samy, Doaa, Martínez, Paloma, Moreno-Sandoval, Antonio, Al-Jumaily, Harith, Hutchison, David, editor, Kanade, Takeo, editor, Kittler, Josef, editor, Kleinberg, Jon M., editor, Mattern, Friedemann, editor, Mitchell, John C., editor, Naor, Moni, editor, Nierstrasz, Oscar, editor, Pandu Rangan, C., editor, Steffen, Bernhard, editor, Sudan, Madhu, editor, Terzopoulos, Demetri, editor, Tygar, Doug, editor, Vardi, Moshe Y., editor, Weikum, Gerhard, editor, Peters, Carol, editor, Jijkoun, Valentin, editor, Mandl, Thomas, editor, Müller, Henning, editor, Oard, Douglas W., editor, Peñas, Anselmo, editor, Petras, Vivien, editor, and Santos, Diana, editor

Published
2008
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47. Detecting Semantic Relations Between Nominals Using Support Vector Machines and Linguistic-Based Rules

Author

Segura-Bedmar, Isabel, Samy, Doaa, Martínez-Fernández, Jose L., Martínez, Paloma, Hutchison, David, editor, Kanade, Takeo, editor, Kittler, Josef, editor, Kleinberg, Jon M., editor, Mattern, Friedemann, editor, Mitchell, John C., editor, Naor, Moni, editor, Nierstrasz, Oscar, editor, Pandu Rangan, C., editor, Steffen, Bernhard, editor, Sudan, Madhu, editor, Terzopoulos, Demetri, editor, Tygar, Doug, editor, Vardi, Moshe Y., editor, Weikum, Gerhard, editor, Meersman, Robert, editor, Tari, Zahir, editor, and Herrero, Pilar, editor

Published
2007
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48. MIRACLE’s Cross-Lingual Question Answering Experiments with Spanish as a Target Language

Author

de Pablo-Sánchez, César, González-Ledesma, Ana, Martínez-Fernández, José Luis, Guirao, José María, Martínez, Paloma, Moreno, Antonio, Hutchison, David, editor, Kanade, Takeo, editor, Kittler, Josef, editor, Kleinberg, Jon M., editor, Mattern, Friedemann, editor, Mitchell, John C., editor, Naor, Moni, editor, Nierstrasz, Oscar, editor, Pandu Rangan, C., editor, Steffen, Bernhard, editor, Sudan, Madhu, editor, Terzopoulos, Demetri, editor, Tygar, Dough, editor, Vardi, Moshe Y., editor, Weikum, Gerhard, editor, Peters, Carol, editor, Gey, Fredric C., editor, Gonzalo, Julio, editor, Müller, Henning, editor, Jones, Gareth J. F., editor, Kluck, Michael, editor, Magnini, Bernardo, editor, and de Rijke, Maarten, editor

Published
2006
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49. MIRACLE at WebCLEF 2005: Combining Web Specific and Linguistic Information

Author

Martínez-González, Ángel, Martínez-Fernández, José Luis, de Pablo-Sánchez, César, Villena-Román, Julio, Hutchison, David, editor, Kanade, Takeo, editor, Kittler, Josef, editor, Kleinberg, Jon M., editor, Mattern, Friedemann, editor, Mitchell, John C., editor, Naor, Moni, editor, Nierstrasz, Oscar, editor, Pandu Rangan, C., editor, Steffen, Bernhard, editor, Sudan, Madhu, editor, Terzopoulos, Demetri, editor, Tygar, Dough, editor, Vardi, Moshe Y., editor, Weikum, Gerhard, editor, Peters, Carol, editor, Gey, Fredric C., editor, Gonzalo, Julio, editor, Müller, Henning, editor, Jones, Gareth J. F., editor, Kluck, Michael, editor, Magnini, Bernardo, editor, and de Rijke, Maarten, editor

Published
2006
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50. Contribución al desarrollo de herramientas CAD para el análisis y diseño de antenas de banda ultra ancha mediante el método de elementos finitos : Contribution to the development of CAD tools for the analysis and design of ultra-wideband antennas by means of the finite element method

Author

Martínez Fernández, José Luis and Gil Gil, José María

Subjects
Telecomunicaciones
Abstract

RESUMEN ------- Esta tesis doctoral está dedicada al desarrollo de herramientas de diseño asistido por ordenador (CAD) y de optimización de antenas de banda ultra ancha (UWB) mediante el método de elementos finitos (FEM). El objetivo de este trabajo es adecuar una técnica de análisis numérico versátil, fiable y precisa como es el FEM, pero a su vez sumamente costosa en términos de recursos de computación, para su uso en conjunción con algoritmos de optimización y la creación de herramientas CAD. Así, gracias a la versatilidad proporcionada por el método de análisis, se pueden abordar optimizaciones ciegas sobre formas arbitrarias, de forma que se puedan explorar y estudiar nuevas geometrías con mejores prestaciones que ayuden a evolucionar el estado del arte en antenas UWB. Es, por tanto, también objetivo de este trabajo el diseño y optimización de geometrías de antena UWB novedosas cuyas prestaciones las sitúen a la cabeza del estado del arte. Teniendo en cuenta estos objetivos, este trabajo se ha dividido en dos partes principales: una dedicada a los fundamentos teóricos que permiten aumentar la eficiencia del FEM de manera que pueda ser integrado en rutinas de optimización, y una segunda dedicada al diseño de antenas de banda ultra ancha con las herramientas desarrolladas. Acompañando estos dos bloques temáticos principales se encuentran también una introducción, cuyo objetivo es presentar los antecedentes y motivaciones del trabajo, y unas conclusiones, cuyo objetivo es resaltar las contribuciones originales de este trabajo y las líneas de trabajo futuras abiertas por este trabajo. Dentro del primer bloque temático, se presentan dos metodologías diferentes cuyo objetivo es dotar de una mayor efiencia al método del elementos finitos: la formulación SFELP y el análisis mediante matrices de admitancia multipropósito (MAM). La primera se basa en el desarrollo de una formulación que permite la obtención de la matriz de admitancia generalizada (GAM) de una estructura electromagnética de una forma eficiente, de manera que puede realizarse la segmentación del dominio mediante la conexión de las GAM de los diferentes segmentos. El análisis mediante MAM se basa, en cambio, en la resolución de problemas electromagnéticos utilizando puertas artificiales, mediante las cuales se pueden establecer condiciones de contorno variables que pueden fijarse a posteriori una vez realizado el análisis electromagnético, mediante simples y eficientes manipulaciones circuitales. De esta manera puede abordarse la optimización de estructuras muy complejas de una forma muy eficiente. El segundo bloque temático se adentra en el diseño y estudio de geometrías de antena UWB con perfiles optimizados para mejorar sus prestaciones. Este bloque se divide en cuatro capítulos en los que se presenta el diseño y optimización de otros tantos tipos de estructura de banda ultra ancha. En el primero de esos capítulos se aborda el estudio y optimización del perfil de antenas de tipo monopolo (tanto estructuras con perfil plano como estructuras tridimensionales) con el objetivo de minimizar las pérdidas de retorno. Como evolución de dichas estructuras, el siguiente capítulo presenta el diseño y optimización de monopolos con perfil plano y banda rechazada mediante la optimización de ranuras en el perfil. En el tercer capítulo se trata el diseño de una antena de apertura con polarización dual con perfil de alimentación optimizado para minimizar las pérdidas de retorno en la banda UWB. Por último, el cuarto diseño aborda la posibilidad del conformado del haz de radiación mediante la optimización del perfil de un dieléctrico utilizado a modo de recubrimiento en una antena de tipo monopolo. ABSTRACT -------- This thesis is devoted to the development of computer aided design (CAD) tools for the optimization of Ultra Wide-Band antennas by means of the Finite Element Method (FEM). The objective of this work is to adequate the versatile and accurate but costly in terms of computational resources, the FEM is, for its use together with optimization algorithms and other CAD tools. Hence, thanks to the versatility provided by the analysis method, blind optimizations can be carried out over arbitrary profiles, so that new geometries can be explored and studied in order to make the state of the art in UWB antennas evolve. Therefore, the design and optimization of novel UWB antennas with performances which make them situate in the head of the state of the art, is another objective of this work. Keeping in mind these objectives, this work has been divided into two main parts: one dedicated to the theoretical basis which allow to increase the efficiency of the FEM so that it can be used together with optimization routines, and a second one dedicated to the design of ultra-wideband antennas with the developed tools. Together with these two main thematic blocks there is also an introduction, whose objective is to present the background and motivations of this work, and a conclusion chapter, whose objective is to highlight the original contributions of this thesis and the future research work related to this thesis. In the first part, two different methodologies are presented, in order to provide the finite element method with a higher efficiency: the SFELP formulation and the MAM-based analysis. The first one is based on the development of a formulation which allows to obtain the GAM of an electromagnetic structure in an efficient way, so that a segmentation of the domain can be performed by means of the connection of the GAM of the different segments. The MAM analysis is based in the use of artificial ports when computing an electromagnetic problem, which allow to establish variable boundary conditions which can be fixed a posteriori once the electromagnetic analysis has been completed, by means of simple and efficient circuital manipulations. Hence, the optimization of very complex structures can be carried out in a very efficient way. The second part presents the design and study of UWB structures with optimized profiles for better performances. This part is divided into four chapters in which the design and optimization of four types of ultra-wideband antennas is performed. The first chapter is devoted to the study and optimization of monopole-like (both planar and non-planar profiles) antennas designed to minimize return losses. As an evolution of these structures, the second chapter presents the design and optimization of frequency notched planar profile monopole antennas in which the notches of the antenna are optimized for optimal performance. The third chapter treats the design of a dual polarized aperture antenna an optimized profile feed for minimum return losses in the UWB band. Finally, the fourth design deals with the possibility of radiation pattern conforming by means of an optimized profile dielectric coating in a monopole antenna.

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2022
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