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  • Early foaming detection in a sweetening unit using PCA

     Askarian, Mahdieh; Musulin, Estanislao; Benitez Iglesias, Raul; Graells Sobre, Moises; Zarghami, Reza
    Mediterranean Congress of Chemical Engineering
    p. 304
    Presentation's date: 2014-10-01
    Presentation of work at congresses

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    The removal of sour gas components from the gas streams using chemical solvents, such as MDEA, is a requirement in most hydrocarbon processing plants. The acid gas constituents (H2S and CO2) react with an aqueous solution in a high-pressure absorber. Subsequently, the solvent is stripped from the acid gas in the regenerator at elevated temperature to reuse it. Figure 1 illustrates a typical gas treating plant employing an alkanolamine. One of the most frequent faults in gas sweetening is amine foaming, which results in the loss of proper vapor-liquid contact, solution hold up and poor solution distribution. Some root causes of foaming includes accumulation of heavy hydrocarbon and solid particle in amine and antifoam trouble. The consequence is off-spec product, downtime and loss of amine and energy. Whenever operators distinguish foaming based process measurement trends, a short term measure is manual injecting of antifoam agent. However, disadvantage of this approach is misdetection due to existence of numerous variables, low experience and unconscious operators. Also, there are some other process disturbances in the system originated in downstream or upstream that can mislead the operator to detect foaming. On the other hand, overdose injection of antifoam has adverse effects on the filtration system. This work proposes a decision support software based on principal component analysis for detection of foaming in a sweetening plant. From the many process variables, operators tend to make decisions based on only one or two of them. Consequently, important information included in other variables, or in their relations, is discarded. This work proposes the use of PCA [1] to reduce the monitoring space without discarding relevant process variance. Due to the importance of process disturbances, PCA cannot be applied using their standard statistics (T2 and SPE), due to the high number of false alarms they produce. However, a 2D scatter plot in the reduced space (Fig. 2) allows performing an early and reliable identification of foaming, thereby supporting operator decisions and reducing operating costs. Results show fast and efficient data analysis for practical fault detection and qualitative decision-making support. Further work is underway regarding quantitative assessment of confidence levels.

  • Detection, quantification and visualization of ryanodine receptor phosphorylation in human atrial myocytes using a novel ratiometric immunofluorescent analysis

     Vallmitjana Lees, Alexander; Molina, P. E.; Herrainz, Adela; Montiel Dacosta, José Antonio; Cinca Cosculluela, Juan; Benitez Iglesias, Raul; Hove-Madsen, Leif
    Frontiers in CardioVascular Biology
    p. S8-
    DOI: 10.1093/cvr/cvu081
    Presentation's date: 2014-07-04
    Presentation of work at congresses

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  • Análisis automático de datos experimentales en fisiología cardiaca

     Escudero Bakx, Gerard; Arboleda Aguinaga, Juan Pablo; Velazquez Lerma, Susana Adriana; Benitez Iglesias, Raul
    Competitive project

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  • Inteligencia artificial avanzada

     Benitez Iglesias, Raul; Escudero Bakx, Gerard; Kanaan Izquierdo, Samir; Masip Rodó, David
    Date of publication: 2013-07-08
    Book

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    En este libro se introducen los conceptos fundamentales de la Inteligencia Artificial, desde una visión muy orientada al reconocimiento de patrones. El lector podrá encontrar una revisión completa de las técnicas avanzadas más usadas en el campo del aprendizaje automático. El texto se ha enfocado desde un punto de vista eminentemente práctico. Las explicaciones teóricas de las diferentes técnicas se basan en la resolución de problemas concretos. Los algoritmos están acompañados de ejemplos, escritos en Python, con aplicaciones directas en ámbitos como el procesado de imágenes o el análisis de textos. Los diferentes capítulos comprenden las técnicas de aprendizaje no supervisado, los métodos de reducción de la dimensionalidad y extracción de características (PCA, NMF, ICA, LDA, MDS), los principales algoritmos de clasificación de patrones (probabilísticos, kNN, SVM y Boosting) y diferentes métodos de optimización.

  • Multilevel analysis of calcium dynamics in stimulated cultures of cardiomyocytes

     Vallmitjana Lees, Alexander; Hove-Madsen, Leif; Barriga, Montserrat; Benitez Iglesias, Raul
    IEEE Engineering in Medicine and Biology Society
    p. 6514-6517
    DOI: 978-1-4577-0216-7/13/$26.00
    Presentation's date: 2013-07-05
    Presentation of work at congresses

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    We present an automatic method to characterize calcium activity in a culture of cardiac cells from a sequence of microscopy fluorescence images. The approach quantifies both the response of each individual cell in the culture to external field stimulation and the propagation properties of calcium wave-fronts, thus providing complementary informa- tion at different physiological levels. The technique classifies the response of each cell as regular or irregular based on a set of dynamical and morphological features of the calcium transients. Isochronal maps were constructed from the local activation times across the culture, and the front propagation was classified as planar or non-planar. The method has been applied to a set of 35 experiments, and the results indicate a significative connection between irregular behavior at the single-cell level and irregular front propagation.

    We present an automatic method to characterize calcium activity in a culture of cardiac cells from a sequence of microscopy fluorescence images. The approach quantifies both the response of each individual cell in the culture to external field stimulation and the propagation properties of calcium wave-fronts, thus providing complementary information at different physiological levels. The technique classifies the response of each cell as regular or irregular based on a set of dynamical and morphological features of the calcium transients. Isochronal maps were constructed from the local activation times across the culture, and the front propagation was classified as planar or non-planar. The method has been applied to a set of 35 experiments, and the results indicate a significative connection between irregular behavior at the single-cell level and irregular front propagation

  • A method to characterize calcium activity in stimulated cultures of cardiac myocytes

     Benitez Iglesias, Raul; Vallmitjana Lees, Alexander; Hove-Madsen, Leif
    Annual Meeting of Biophysical Society
    Presentation's date: 2013-02-06
    Presentation of work at congresses

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  • Disrupting Ca2+ waves, but not Ca2+ leak, protects against cardiac arrhythmia

     Jones, Peter; Bai, Yunlong; Vallmitjana Lees, Alexander; Wang, Ruiwu; Clark, Robert; Zhou, Qiang; Benitez Iglesias, Raul; Hove-Madsen, Leif; Chen, S.
    International Society for Heart Research Australasian Section Annual Scientific Meeting
    p. S78
    Presentation's date: 2012-08-16
    Presentation of work at congresses

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  • Automatic method for the detection and characterization of Calcium activity in cardiac cells

     Vallmitjana Lees, Alexander; Alvarez Lacalle, Enrique; Hove-Madsen, Leif; Benitez Iglesias, Raul
    IEEE International Symposium on Biomedical Imaging
    Presentation's date: 2012-05-05
    Presentation of work at congresses

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  • Detection and classification of spontaneous calcium release events in cardiac myocytes

     Benitez Iglesias, Raul; Vallmitjana Lees, Alexander; Hove-Madsen, Leif; Jones, Peter P.
    Annual Meeting of Biophysical Society
    p. 309
    DOI: 10.1016/j.bpj.2011.11.1702
    Presentation's date: 2012-02-27
    Presentation of work at congresses

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  • Adenosine A2A receptor activation decreases beat-to-beat stability of intracellular calcium transients and their propagation in atrial myocytes

     Barriga, Montserrat; Molina, Cristina E.; Llach, Anna; Cabello, Núria; Vallmitjana Lees, Alexander; Benitez Iglesias, Raul; Padró, Josep; Cinca Cosculluela, Juan; Hove-Madsen, Leif
    Annual Meeting of Biophysical Society
    p. 553
    DOI: 10.1016/j.bpj.2011.11.3017
    Presentation's date: 2012-02-28
    Presentation of work at congresses

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  • Identification of Nonlinear Cardiac Cell Dynamics Using Radial Basis Function Regression

     Kanaan Izquierdo, Samir; Velazquez Lerma, Susana Adriana; Benitez Iglesias, Raul
    IEEE Engineering in Medicine and Biology Society
    p. 6833-6836
    Presentation's date: 2011-09-03
    Presentation of work at congresses

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  • Smart calibration for video game play by people with a movement impairment

     Perez, Sergi; Benitez Iglesias, Raul; Reinkensmeyer, David J.
    IEEE Engineering in Medicine and Biology Society
    p. 6741-6744
    Presentation's date: 2011-09-03
    Presentation of work at congresses

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  • Effects of atrial fibrillation on the distribution, dimensions, and frequency of calcium sparks in human atrial myocytes

     Barriga, Montserrat; Llach, Anna; Alvarez Lacalle, Enrique; Cabello, N.; Ballester, B.; Vallmitjana Lees, Alexander; Muñoz, C.; Benitez Iglesias, Raul; Cinca Cosculluela, Juan; Hove-Madsen, Leif
    European Society of Cardiology Congress
    p. 468
    Presentation's date: 2011-08-27
    Presentation of work at congresses

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  • Access to the full text
    Identification of intracellular calcium dynamics in stimulated cardiomyocytes  Open access

     Vallmitjana Lees, Alexander; Barriga, Montserrat; Nenadic, Zoran; Llach, Anna; Alvarez Lacalle, Enrique; Hove-Madsen, Leif; Benitez Iglesias, Raul
    IEEE Engineering in Medicine and Biology Society
    p. 64
    DOI: 10.1109/IEMBS.2010.5626238
    Presentation's date: 2010-09-01
    Presentation of work at congresses

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    We have developed an automatic method for the analysis and identification of dynamical regimes in intracellular calcium patterns from confocal calcium images. The method allows the identification of different dynamical patterns such as spatially concordant and discordant alternans, irregular behavior or phase-locking regimes such as period doubling or halving. The method can be applied to the analysis of different cardiac pathologies related to anomalies at the cellular level such as ventricular reentrant arrhythmias.

  • Effect of the resting membrane potential on the distribution, dimensions, and frequency of calcium sparks in human atrial myocytes

     Barriga, Montserrat; Alvarez Lacalle, Enrique; Llach, Anna; Vallmitjana Lees, Alexander; Muñoz, C.E.; Cinca Cosculluela, Juan; Benitez Iglesias, Raul; Hove-Madsen, Leif
    European Society of Cardiology Congress
    Presentation's date: 2010-09-01
    Presentation of work at congresses

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  • On-Line Fault Diagnosis Based on the Identification of Transient Stages

     Monroy Chora, Isaac; Benitez Iglesias, Raul; Escudero Bakx, Gerard; Graells Sobre, Moises
    European Symposium on Computer Aided Process Engineering
    p. 1453-1458
    Presentation's date: 2010-06-07
    Presentation of work at congresses

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  • Non-ideal behavior in the electronic implementation of chaotic dynamical systems

     Benitez Iglesias, Raul; Cosp Vilella, Jordi
    Emerging Topics in Dynamical Systems and Partial Differential Equations
    Presentation's date: 2010-06-01
    Presentation of work at congresses

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  • DESARROLLO DE TÉCNICAS DE ANÁLISIS DE SITEMAS COMPLEJOS PARA EL ESTUDIO DE PROBLEMAS EN FISIOLOGÍA CARDÍACA

     Velazquez Lerma, Susana Adriana; Escudero Bakx, Gerard; Kanaan Izquierdo, Samir; Vallmitjana Lees, Alexander; Benitez Iglesias, Raul
    Competitive project

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  • Efecto del potencial de membrana sobre las dimensiones, la cinética y la frecuencia de la liberación local de calcio en miocitos auriculares humanos

     Barriga, Montserrat; Alvarez Lacalle, Enrique; Llach, Anna; Vallmitjana Lees, Alexander; Muñoz Guijosa, Cristian; Cinca Cosculluela, Juan; Benitez Iglesias, Raul; Hove-Madsen, Leif
    Congreso de la Sociedad Española de Cardiología
    p. 95
    Presentation's date: 2009-10-21
    Presentation of work at congresses

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  • RED TRANSFRONTERIZA PARA LA DETERMINACION Y GESTION DE FLUJOS DE AGUA, CARBONO Y ENERGIA

     Mazon Bueso, Jordi; Meca Alvarez, Esteban; Pino Gonzalez, David; Benitez Iglesias, Raul
    Competitive project

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  • DICA enhanced SVM classification approach to fault diagnosis for chemical processes

     Monroy Chora, Isaac; Benitez Iglesias, Raul; Escudero Bakx, Gerard; Graells Sobre, Moises
    European Symposium on Computer Aided Process Engineering
    p. 267-272
    DOI: 10.1016/S1570-7946(09)70045-8
    Presentation's date: 2009-06-04
    Presentation of work at congresses

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  • MÉTODO DE DETECCIÓN DE EVENTOS LOCALES DE LIBERACIÓN DE CALCIO INTRACELULAR

     Benitez Iglesias, Raul; Alvarez Lacalle, Enrique; Hove-Madsen, Leif
    Date of request: 2009-03-13
    Invention patent

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    Método de detección de eventos locales de liberación de calcio intracelular.

    La presente invención trata de un método de detección de eventos locales de liberación de calcio intracelular comprendiendo las siguientes etapas:

    - adquirir una secuencia de imágenes bidimensionales de una sección determinada de una o más células, incluyendo información relativa a actividad de calcio intracelular;

    - normalizar dichas imágenes;

    - realizar un análisis estadístico de la distribución espacio-temporal de píxeles en dicha secuencia de imágenes normalizadas, para determinar unas regiones de interés, y determinar que dichas regiones de interés son candidatas a contener un evento local de liberación de calcio intracelular de interés; y.

    - realizar las siguientes etapas, automáticamente y de manera previa a dicho análisis estadístico:

    - detectar eventos globales de liberación de calcio en una o más de las imágenes de dicha sucesión de imágenes; y

    - realizar dicho análisis estadístico solamente sobre las imágenes en las cuales no se han detectado eventos globales de liberación de calcio.

  • Metodo de detección de eventos locales de Iiberación de calcio intracelular

     Benitez Iglesias, Raul; Alvarez Lacalle, Enrique; Alvarez-Lacalle, Enric; Hove-Madsen, Leif
    Date of request: 2009-03-13
    Invention patent

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    Método de detección de eventos locales de liberación de calcio intracelular.

    La presente invención trata de un método de detección de eventos locales de liberación de calcio intracelular comprendiendo las siguientes etapas:

    - adquirir una secuencia de imágenes bidimensionales de una sección determinada de una o más células, incluyendo información relativa a actividad de calcio intracelular;

    - normalizar dichas imágenes;

    - realizar un análisis estadístico de la distribución espacio-temporal de píxeles en dicha secuencia de imágenes normalizadas, para determinar unas regiones de interés, y determinar que dichas regiones de interés son candidatas a contener un evento local de liberación de calcio intracelular de interés; y.

    - realizar las siguientes etapas, automáticamente y de manera previa a dicho análisis estadístico:

    - detectar eventos globales de liberación de calcio en una o más de las imágenes de dicha sucesión de imágenes; y

    - realizar dicho análisis estadístico solamente sobre las imágenes en las cuales no se han detectado eventos globales de liberación de calcio.

  • Denoising de señales mediante técnicas probabilísticas

     Benitez Iglesias, Raul
    Congreso de Física Estadística
    p. 57
    Presentation of work at congresses

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  • Detección y clasificación de potenciales de acción en señales neurofisiológicas mediante técnicas bayesianas

     Benitez Iglesias, Raul
    Nolineal 2007 : Nuevos retos y perspectivas de la dinámica no lineal y sus aplicaciones
    Presentation's date: 2007-06-06
    Presentation of work at congresses

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  • Detección y clasificación de potenciales de acción en señales neurofisiológicas mediante técnicas bayesianas

     Benitez Iglesias, Raul
    Nolineal 2007 : Nuevos retos y perspectivas de la dinámica no lineal y sus aplicaciones
    p. 42
    Presentation of work at congresses

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  • ORDEN, RUIDO Y DINÁMICAS EMERGENTES BAJO NOLINEALIDADES

     Ramirez de La Piscina Millan, Laureano; Peñaranda Ayllon, Angelina; Haurie Ibarra, Laia; Meca Alvarez, Esteban; Rodriguez Cantalapiedra, Inmaculada; Lacasta Palacio, Ana Maria; Benitez Iglesias, Raul; Formosa Mitjans, Joan; Gonzalez Cinca, Ricardo; Suñol Galofre, Francesc Xavier; Arias Calderón, Santiago
    Competitive project

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  • 9è Premi a la Qualitat en la Docència Universitària

     Domingo Peña, Joan; Valero Garcia, Miguel; Calviño Tavares, Francisco; Armengol Cebrian, Jesús; Bara Temes, Francisco Javier; Almajano Pablos, Maria Pilar; Robert i Sanxis, Francesc Josep; Pretel Sanchez, M. del Carmen; Usandizaga Calparsoro, Miguel M.; Giraldo Giraldo, Beatriz F.; Gomez Urgelles, Joan Vicenç; Gorchs Altarriba, Roser; Perez Poch, Antoni; Cadenato Matia, Ana Maria; Benitez Iglesias, Raul; Guerrero Zapata, Josep Maria; Navarro Moldes, Leandro; Jordana Barnils, Josep; Martínez García, Herminio
    Award or recognition

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  • III Premios de la UEM a la Calidad en la Docencia Universitaria

     Domingo Peña, Joan; Valero Garcia, Miguel; Calviño Tavares, Francisco; Armengol Cebrian, Jesús; Bara Temes, Francisco Javier; Almajano Pablos, Maria Pilar; Robert i Sanxis, Francesc Josep; Pretel Sanchez, M. del Carmen; Usandizaga Calparsoro, Miguel M.; Giraldo Giraldo, Beatriz F.; Gomez Urgelles, Joan Vicenç; Gorchs Altarriba, Roser; Perez Poch, Antoni; Cadenato Matia, Ana Maria; Benitez Iglesias, Raul; Guerrero Zapata, Josep Maria; Navarro Moldes, Leandro; Jordana Barnils, Josep; Martínez García, Herminio
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  • Premi Jaume Vicens Vives a la Qualitat en la Docència 2006

     Domingo Peña, Joan; Calviño Tavares, Francisco; Armengol Cebrian, Jesús; Almajano Pablos, Maria Pilar; Robert i Sanxis, Francesc Josep; Bara Temes, Francisco Javier; Pretel Sanchez, M. del Carmen; Jordana Barnils, Josep; Martínez García, Herminio; Valero Garcia, Miguel; Usandizaga Calparsoro, Miguel M.; Giraldo Giraldo, Beatriz F.; Gomez Urgelles, Joan Vicenç; Gorchs Altarriba, Roser; Perez Poch, Antoni; Cadenato Matia, Ana Maria; Guerrero Zapata, Josep Maria; Navarro Moldes, Leandro; Benitez Iglesias, Raul
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  • Stochastic sharp-interface projection of a phase-field model

     Benitez Iglesias, Raul
    Congreso de Física Estadística
    Presentation's date: 2005-06-27
    Presentation of work at congresses

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  • Interpretació dels resultats d'una activitat d'AC en l'àmbit de l'automàtica

     Benitez Iglesias, Raul
    Jornada d'anàlisi d'experiències d'aprenentatge cooperatiu
    Presentation's date: 2005-06-01
    Presentation of work at congresses

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  • Grup de Turbulencia, Fluctuacions i Difusió (Ayuda para grupos de investigación consolidados)

     Ramirez de La Piscina Millan, Laureano; Platonov, Alexei; Carrillo Cortes, Jose Alejandro; Sekula, Emil; Peñaranda Ayllon, Angelina; Echebarria Dominguez, Blas; Auguet Sangra, Carlota Eugenia; Meca Alvarez, Esteban; Cami Babra, Enrique; Castilla Lopez, Roberto; Rodriguez Cantalapiedra, Inmaculada; Grau Barcelo, Joan; Lacasta Palacio, Ana Maria; Redondo Apraiz, Jose Manuel; Sanchez Ariz, Miguel A.; Benitez Iglesias, Raul; Gonzalez Cinca, Ricardo
    Competitive project

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  • IEEE transactions on biomedical engineering

     Benitez Iglesias, Raul
    Collaboration in journals

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  • Stochastic sharp-interface projection of a phase-field model

     Benitez Iglesias, Raul; Ramirez de La Piscina Millan, Laureano
    Congreso de Física Estadística
    p. 17
    Presentation of work at congresses

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  • Phase-field study of transient stages and fluctuations in solidification  Open access

     Benitez Iglesias, Raul
    Department of Applied Physics, Universitat Politècnica de Catalunya
    Theses

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    L'estudi de la formació de microstructures en processos de solidificació té importants aplicacions científiques i tecnològiques. L'aparició d'aquestes estructures determina les propietats elèctriques i mecàniques del material solidificat, i té per tant un important interès tecnològic. La majoria d'aquestes estructures tenen el seu origen en una desestabilització morfològica de la interfase sòlid-líquid que es produeix a mesura que el front avança. Per aquest motiu, l'estudi del comportament dinàmic de la interfase resulta essencial per entendre els mecanismes que intervenen en la creació d'aquests patrons. Els processos de solidificació solen descriure's mitjançant problemes de contorn mòbil. Aquestes formulacions consten d'equacions per a la difusió del calor i de massa en les fases sòlida i líquida, que s'han de resoldre imposant l'acompliment de diverses condicions de contorn mòbils a la interfase. Els problemes de contorn mòbil, malgrat contenir tots els elements que intervenen en la dinàmica i ser de molta utilitat en l'àmbit de l'enginyeria, requereixen un cost computacional que no permet simular sistemes reals en règims interfacials complexos. Els mètodes de camp de fase (phase-field methods), van aparèixer a principis dels anys vuitanta com una eina computacional que permetia l'estudi de fenòmens interfacials de caire general. Aquests mètodes descriuen la forma de la interfase mitjançant un camp continu que pren valors diferents i constants en les dues fases. La dinàmica d'aquest camp és llavors acoblada al camp de difusió de calor o massa que determina l'avanç del front de solidificació. Un dels avantatges d'aquests mètodes és que la seva simulació no requereix d'algorismes de seguiment de la interfase (front tracking algorithsms). És ben conegut que les característiques principals de les microestructures en solidificació, es determinen durant els transitoris inicials en els que els corrents de massa i calor s'adapten a la evolució dinàmica del front. Un dels objectius en aquesta tesi és el de fer servir mètodes de camp de fase per descriure de forma quantitativa aquests transitoris. Per comprovar la validesa del nostre procediment, es realitza una comparació quantitativa entre els resultats numèrics obtinguts i diferents prediccions analítiques derivades del problema de contorn mòbil. Per un altra banda, la desestabilització del front es veu afectada per la presència de fluctuacions al sistema. Aquestes pertorbacions microscòpiques poden tenir el seu origen a les fluctuacions termodinàmiques internes, o bé ser conseqüència de imperfeccions experimentals que actuen com a font externa de soroll. El segon objectiu d'aquesta tesi és la introducció de fluctuacions en mètodes de camp de fase, de forma que es pugui estudiar l'amplificació dinàmica de les pertorbacions microscòpiques que acaben donant lloc a estructures macroscòpiques. Per finalitzar, analitzem el problema de la selecció en solidificació direccional. Estudiem els règims lineal i no-lineal, tot determinant les condicions, el moment i la forma en que apareixen les estructures dendrítiques i cel·lulars.

    Crystal growth is a non-equilibrium process which involves physical mechanisms at very different scales. When a solidification front advances, mass and heat diffusion processes are combined with interfacial phenomena like capillarity or kinetic attachment. A complex interplay between these mechanisms gives rise to complex interfacial structures like snowflakes or cellular patterns. The formation of microstructures in solidification has both a scientific and a technological interest. On one hand, the study of the different interfacial structures constitutes a fundamental problem in the field of non-equilibrium pattern-forming systems. On the other side, from a technological point of view, the presence of microstructures determines the final mechanical and electrical properties of the processed material. Directional solidification is a controlled solidification technique which reproduces the conditions occurring in some important metallurgical processes like material casting or zone melting refining procedures. In a directional solidification experiment, the alloy sample is pulled at a constant velocity towards the cold region of an externally-imposed temperature gradient. Depending on the growth conditions, a morphological destabilization of the solid-liquid interface occurs during early transient stages. These initial transients are associated to a solute redistribution process due to the adaptation of the concentration field to the forced motion of the sample. The main objective of this thesis is to study the dynamical evolution of the morphological deformations of the front from these initial transients to the final stages where the properties of the interfacial pattern are determined. An important point in this process is that the internal fluctuations of the system play the role of an initiation mechanism for the morphological deformations of the front. During the initial transients, some of these microscopic perturbations are amplified by several orders of magnitude, and a range of wavelengths becomes morphologically unstable. The interfacial deformations of the front can be then characterized by means of power spectrum techniques. In order to study the dynamical evolution of the solidification front in directional solidification, we have used both theoretical and computational approaches: The main computational technique used in this thesis is the phase-field approach, which is a powerful method to simulate complex interfacial phenomena. The model equations describe the evolution of a continuous field , which takes different constant values at the solid and liquid bulks of the system. This field is then coupled with equations for the mass diffusion, and allows performing numerical studies without simulating the standard Stefan-like moving boundary problem. The phase-field method provides a diffuse interface description in which the transition from solid to liquid happens in a region of a certain thickness. The interface thickness introduces a new length in the simulations which must be taken into account to recover quantitative results. One major point in this thesis concerns with the introduction of fluctuations in phase-field methods. In the particular case of variational phase-field formulations -in which the model equations can be derived from a single free energy functional for the whole system-, the introduction of fluctuations can be done by applying the Fluctuation-Dissipation theorem. Variational formulations, however, although their appealing structure, present a poor computational efficiency and cannot be used to obtain quantitative results. To this extent, we have derived a general approach which does not relay in the Fluctuation-Dissipation assumption and permits to introduce fluctuations in both variational and non-variational phase-field formulations. Well-established analytical techniques like boundary integral methods for the transient front position and linear stability analysis of the interface during the transient have been used as theoretical predictions for the computational results. The dynamical evolution of the solidification front can be divided in two stages: A linear regime where the initial noise is amplified, and a non-linear coarsening process where the final properties of the interfacial pattern are selected. We have studied these different stages of the solidification process by using the phase-field approach, and good agreement is obtained when comparing with well-established theoretical and experimental predictions.

  • Análisis de las estrategias de evaluación en una actividad de aprendizaje cooperativo

     Benitez Iglesias, Raul
    IV Jornada sobre Aprendizaje Cooperativo
    Presentation's date: 2004-07-02
    Presentation of work at congresses

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  • Aprendizaje cooperativo basado en problemas en el diseño y desarrollo de proyectos de ingeniería

     Benitez Iglesias, Raul
    Congreso Universitario de Innovación Educativa en las Enseñanzas Técnicas
    Presentation's date: 2004-07-26
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  • Access to the full text
    Phase-field models in interfacial pattern formation out of equilibrium  Open access

     Gonzalez Cinca, Ricardo; Folch, R; Benitez Iglesias, Raul; Ramirez de La Piscina Millan, Laureano; Casademunt Viader, Jaume; Hrndez-Machado, A
    Date of publication: 2004-06
    Book chapter

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  • Quantitative phase-field simulations to the wavelength selection during alloy redistribution transients

     Benitez Iglesias, Raul
    Fluctuations and Noise in Photonics and Quantum Optics II - 2nd SPIE Symposium on Fluctuations and Noise
    Presentation's date: 2004-05-26
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  • Aprendizaje cooperativo basado en proyectos en el diseño y desarrollo de proyectos de ingeniería

     Benitez Iglesias, Raul; Giraldo Giraldo, Beatriz F.; Domingo Peña, Joan
    Congreso Universitario de Innovación Educativa en las Enseñanzas Técnicas
    p. 1-7
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  • Autoorganización en sistemas complejos bajo fluctuaciones

     Ramirez de La Piscina Millan, Laureano; Peñaranda Ayllon, Angelina; Auguet Sangra, Carlota Eugenia; Meca Alvarez, Esteban; Cami Babra, Enrique; Rodriguez Cantalapiedra, Inmaculada; Lacasta Palacio, Ana Maria; Benitez Iglesias, Raul; Gonzalez Cinca, Ricardo
    Competitive project

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  • Quantitative phase-field simulations to the wavelength selection during alloy redistribution transients

     Benitez Iglesias, Raul; Ramirez de La Piscina Millan, Laureano
    Fluctuations and Noise in Photonics and Quantum Optics II - 2nd SPIE Symposium on Fluctuations and Noise
    p. 58-67
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  • Algunos de los roles más habituales de los estudiantes en los grupos cooperativos

     Domingo Peña, Joan; Martínez García, Herminio; Giraldo Giraldo, Beatriz F.; Benitez Iglesias, Raul
    IV Jornada sobre Aprendizaje Cooperativo
    p. 39-47
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  • Análisis de las estrategias de evaluación en una actividad de aprendizaje cooperativo

     Benitez Iglesias, Raul; Giraldo Giraldo, Beatriz F.
    IV Jornada sobre Aprendizaje Cooperativo
    p. 161-165
    Presentation of work at congresses

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  • Descripcion cuantitativa de las fluctuaciones en solidificacion direccional

     Benitez Iglesias, Raul
    Congreso de Física Estadística
    Presentation's date: 2003-10-23
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  • El aprendizaje cooperativo en las actividades universitarias no presenciales

     Benitez Iglesias, Raul
    Tercera Jornada sobre Aprendizaje Cooperativo
    Presentation's date: 2003-07-17
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  • El Aprendizaje Cooperativo, una vía hacia la excelencia docente

     Domingo, Joan; Bará, J; Valero Cortes, Mateo; Batet Miracle, Lluis; Pretel Sanchez, M. del Carmen; Almajano Pablos, Maria Pilar; Armengol Cebrian, Jesús; Sánchez, F J; JORDANA, J; Navarro Moldes, Leandro; Gómez, J; Benitez Iglesias, Raul; Rincón, D; Barraco Serra, Marc; Muñoz Gracia, Maria del Pilar
    Congreso de la Red Estatal de Docencia Universitaria (RED-U)
    Presentation's date: 2003-01-01
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  • Descripcion cuantitativa de las fluctuaciones en solidificacion direccional

     Benitez Iglesias, Raul; Ramirez de La Piscina Millan, Laureano
    Congreso de Física Estadística
    Presentation of work at congresses

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