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Apoyo institucional del ICE-UPC a las dinámicas de innovación docente: Proyecto RIMA

Tue, 21 May 2013 17:25:49 GMT

Title: Apoyo institucional del ICE-UPC a las dinámicas de innovación docente: Proyecto RIMA Authors: Martínez Martínez, María del Rosario; Salán Ballesteros, Maria Núria; Adam, Araceli; Darnell, Isabel; Corral Manuel de Villena, Ignacio de; Gallego Fernández, María Isabel; Portet Cortés, Esperanza; Torra Bitlloch, Immaculada Abstract: En los últimos años, desde el Instituto de Ciencias de la Educación de la Universidad Politécnica de Cataluña (ICE - UPC), se ha incentiva do l a Innovación Docente mediante múltiples iniciativas. Desde 2007, con la creación del Proyecto RIMA (Investigación e Innovación en Metodologías de Aprendizaje - Recerca i Innovació en Metodologies d’Aprenentatge) y de su entorno virtual asociado (www.upc.ed u/rima), el apoyo a la innovación docente se completa con un proyecto coordinado, que facilita la confluencia de esfuerzos de grupos de profesorado con interés en este ámbito. En la presente comunicación y partiendo de los resultados y experiencias de los últimos años en adaptación e implantación de metodologías de innovación docente en la UPC, se realiza una reflexión sobre la acogida e incidencia de esta iniciativa en la adaptación a los nuevos planes de estudio del Espacio Europeo de E ducación Superior ( EEES), y en el planteamiento de nuevos objetivos institucionales referidos tanto al tema de la participación en innovación docente como a las nuevas metodologías y a la mejora de la calidad docente.

Multi-objective design optimization of morphing UAV aerofoil/wing using hybridised MOGA

Tue, 21 May 2013 11:42:48 GMT

Title: Multi-objective design optimization of morphing UAV aerofoil/wing using hybridised MOGA Authors: Lee, DongSeop; Gonzalez, L F.; Periaux, Jacques; Bugeda Castelltort, Gabriel Abstract: The paper investigates two advanced Computational Intelligence Systems (CIS) for a morphing Unmanned Aerial Vehicle(UAV) aerofoil/wing shape design optimisation. The first CIS uses Genetic Algorithm (GA) and the second CIS uses Hybridized GA (HGA) with the concept of Nash-Equilibrium to speed up the optimisation process. During the optimisation, Nash-Game will act as a pre-conditioner. Both CISs; GA and HGA, are based on Pareto optimality and they are coupled to Euler based Computational Fluid Dynamic (CFD) analyser and one type of Computer Aided Design(CAD) system during the optimisation.

Novel polycarbonate-graphene nanocomposite foams prepared by CO2 dissolution

Fri, 17 May 2013 14:42:23 GMT

Title: Novel polycarbonate-graphene nanocomposite foams prepared by CO2 dissolution Authors: Gedler, Gabriel; Sousa Pais Antunes, Marcelo de; Redondo Realinho, Vera Cristina de; Velasco Perero, José Ignacio Abstract: Polycarbonate foams reinforced with 0,5 wt% of graphene were obtained by firstly melt-mixing the polycarbonate and graphene in an internal mixer, compression-moulding the melt-compounded grinded material and lastly dissolving CO2 inside a high pressure vessel. The CO2 desorption behaviour in the unfilled polycarbonate and nanocomposite was studied in terms of the CO2 saturation concentration and desorption diffusion coefficient, with the graphene-filled nanocomposite displaying a higher CO2 loss rate when compared to the neat polycarbonate. The cellular structure of the foams was found to be highly dependent on the saturation/foaming temperature, with smaller cell sizes being obtained with decreasing the temperature. Another parameter that had an important influence was the residual pressure, with higher residual pressure values resulting in foams with more uniform and regular cells. Description: Originally published as "IOP Conference Series: Materials Science and Engineering", vol. 31, no 1, 2012. DOI:10.1088/1757-899X/31/1/012008. .

Influence of foaming process on the structure-properties relationship of foamed LDPE/silica nanocomposites

Fri, 17 May 2013 13:27:52 GMT

Title: Influence of foaming process on the structure-properties relationship of foamed LDPE/silica nanocomposites Authors: Saiz Arroyo, Cristina; Rodríguez Pérez, Miguel Ángel; Velasco Perero, José Ignacio; Saja, José Antonio de Abstract: In this paper LDPE/silica nanocomposites are foamed by two different processes. First one is the pressure quench method which is based on the use of a physical blowing agent and second one is the improved compression moulding technique. As the latter process uses a chemical blowing agent, both types of foamed nanocomposites will provide very useful information about the relationship between foaming process-microstructure and macroscopic properties. Results have revealed how silica nanoparticles are able to act as nucleating sites during foaming step in both processes; however, the optimum amount of particles strongly depends on the foaming route. Thermal and mechanical properties of solid and foamed nanocomposites have been analyzed by means of thermogravimetric analysis and compression tests. Results have revealed that nanosilica particles act as effective nucleating agents, not only reducing cell size and increasing cell density but also achieving more homogeneous cellular structures. Thermal and mechanical properties are improved due to the presence of silica nanoparticles. It has been found that the improvement degree reached for samples produced using chemical blowing agents is greater than that achieved for samples produced using physical blowing agents.

Modelling viscoelastic behaviour of carbón nanotube-reinforced thermo-plastics

Thu, 16 May 2013 08:54:11 GMT

Title: Modelling viscoelastic behaviour of carbón nanotube-reinforced thermo-plastics Authors: Otero Gruer, Fermín Enrique; Oller Martínez, Sergio Horacio; Martínez García, Javier; Salomón, Ramón Omar Abstract: Carbon nanotubes (CNTs), since their discovery by Lijima (S. Lijima, Nature, 354:56-58 (1991)), are considered a new generation of reinforcement. Their "nano" size structure makes them potentially free of defects, which provides them with excellent physical properties. There are two main nanotube types: single wall nanotubes (SWCNTs), which are made of a single wall tube; and multiwall nanotubes (MWCNTs), which consist in several concentric walls, one inside the other. A key factor for the reinforcement efficiency in a composite it is the interface bonding between the CNTs and the matrix. This work presents a new constitutive model to predict the mechanical performance of composites made of a thermo-plastic matrix reinforced with CNTs. The model takes into account explicitly the mechanical contribution of the interface between the matrix and the CNTs (F. Otero et. al., Comp Structures, 94:2920-2930 (2012)). The constitutive model is based in the mixing theory, which obtains the composite performance from the response of each constituent component, each one simulated with its own constitutive law. The model has been implemented into an in-house FEM code: PLCd. As an application example, this code is used to predict the mechanical properties of a straight beam with different material configurations. In this case, a viscoelastic constitutive model is proposed for the polymeric matrix. The viscous response within the elastic range of the materials is studied. This response shows a high capacity of energy dissipation in composites reinforced with MWCNTs.

The particle finite element method (PFEM): an effective numerical technique for solving marine, naval and harbour engineering problems

Wed, 15 May 2013 13:36:16 GMT

Title: The particle finite element method (PFEM): an effective numerical technique for solving marine, naval and harbour engineering problems Authors: Oñate Ibáñez de Navarra, Eugenio; Idelsohn Barg, Sergio Rodolfo; Celigueta Jordana, Miguel Ángel; Suárez Arroyo, Benjamín Abstract: We present some developments in the Particle Finite Element Method (PFEM) for the solution of complex coupled problems in marine, naval and harbour engineering involving fluid-soil-structure interaction (FSSI). The PFEM uses an updated Lagrangian description to model the motion of nodes (particles) in a continuum domain containing fluid, soil/rock and structures subdomains. A mesh connects the nodes defining the discretized domain where the governing equations for each of the constituent materials are solved with the FEM. The stabilization for dealing with an incompressibility material is introduced via the finite calculus (FIC) method. An incremental iterative scheme for solving the non linear transient FSSI problem is described. The procedure to model frictional contact conditions and material erosion at fluid-solid and solid-solid interfaces is described. We present examples of application of the PFEM to solve FSSI problems in marine, naval and harbour engineering such as the motion of rocks by water streams, the stability of breakwaters and constructions under sea waves, the sinking of ships and the collision of a ship with ice blocks.

Estudio de la resistencia a fatiga térmica en moldes de inyección de aluminio utilizando aceros de alta conductividad térmica

Fri, 10 May 2013 13:46:12 GMT

Title: Estudio de la resistencia a fatiga térmica en moldes de inyección de aluminio utilizando aceros de alta conductividad térmica Authors: Molas, Sílvia; Hamasaiid, Anwar; Llobet, Albert; Valls, Isaac; Casellas Padró, Daniel; Riera Colom, María Dolores Abstract: La mayoría de los mecanismos de fallo que determinan la durabilidad de un molde de inyección de aluminio a alta presión están relacionados con las solicitaciones termo-mecánicas de la superficie. En cada ciclo, la superficie de la herramienta está expuest a a elevadas variaciones de temperatura y cargas mecánicas que ocasionan la pérdida de propiedades superficiales (dureza, resistencia, etc.). La variación de las propiedades superficiales y las tensiones termo-mecánicas generadas en los ciclos de inyección inducen la aparición de grietas. A fin de retardar la aparición de estas grietas, se ha desarrollado una nueva generación de aceros de herramienta de trabajo en caliente denominados HTCS® (High Thermal Conductivity Steels) caracterizados por poseer elevados valores de difusividad térmica combinados con elevadas propiedades termo-mecánicas, comparados con los aceros de trabajo en caliente convencionales. Estas propiedades, sobre todo la difusividad térmica elevada, tienen su principal efecto en la reducción de las tensiones superficiales generadas en las herramientas debido a los gradientes térmicos durante el servicio, Esta reducción de tensiones se traduce en un aumento de la vida útil del molde de inyección. En este trabajo se evalúa el efecto de la conductividad térmica del acero de herramientas en la aparición y propagación de grietas por fatiga térmica . Para ello, se han fabricado dos moldes experimenta les de inyección de aluminio a alta presión con la misma geometría y dureza. Un molde se ha fabricado con acero de trabajo en caliente convencional (AISI Hll) y el otro molde con acero de alta conductividad térmica (HTCS®). Se ha realizado el seguimiento de la aparición y propagación de las grietas por fatiga térmica en los dos moldes durante el servicio. Para poder investigar y entender mejor la relación entre las diferencias térmicas y las tensiones superficiales generadas en los dos moldes experimenta les, se ha utilizado un modelo simple de Simulación por Elementos Finitos representativo de una sección del molde real.

Estudio comparativo del conformado en caliente de un acero microaleado usando criterios termodinámicos continuos y criterios fenomenológicos

Fri, 10 May 2013 13:22:35 GMT

Title: Estudio comparativo del conformado en caliente de un acero microaleado usando criterios termodinámicos continuos y criterios fenomenológicos Authors: Alcelay Larrión, José Ignacio; Al Omar Mesnaoui, Anas; Prado Pozuelo, José Manuel Abstract: En las últimas décadas, los mapas de procesado han sido ampliamente utilizados para diseñar, controlar y optimizar los procesos de conformado en caliente. En el presente trabajo, se presenta un estudio comparativo entre mapas de procesado elaborados usando criterios termodinámicos continuos y criterios fenomenológicos. Por ello, se llevaron a cabo ensayos de compresión en caliente en el rango de temperaturas 900 - 1150 ºC y de velocidades de deformación i: = 10-4 - 10 s-1 . El comportamiento en caliente del acero estudiado ha sido estudiado analizando las curvas de fluencia y la interacción entre el comportamiento microestructural y los parámetros de control del proceso de deformación. El estudio comparativo de los mapas de procesado muestra la diferencia entre las posiciones de los distintos dominios de deformación plástica, según el criterio de inestabilidad usado. Además, el análisis de dichos mapas indica que el acero estudiado no sufre ningún tipo de inestabilidad plástica . Sin embargo, los mapas correspondientes a la deformación ¡; = 0,6 revelan la existencia de un dominio de recristalización dinámica, considerado como el dominio más eficiente dentro de la región segura de procesado. Este dominio está centrado a 1150 ºC y 10 s·1.; In the last decades, processing maps have been widely used to design, control and optimize hot forming processes. In this paper, we present a comparative study of processing maps constructed using phenomenological and thermodynamic continuum criteria. Therefore, hot compression tests were carried out in the temperature and strain rate ranging from 900 to 1150 ºC and 10-• to 10 s-1. The hot deformation behavior of studied steel has been investigated analyzing the flow curves and the interaction between the microstructural behavior and parameters control of the deformation process. The comparative study of processing maps show the difference between the positions of plastic deformation domains predicted by the two instability criteria. The analysis of the maps indicates that the steel does not undergo any plastic instability. However, the maps corresponding to deformation E = 0,6 reveal the existence of a domain of dynamic recrystallization, considered the most efficient domain within the safe region processing. This domain is centered at 1150 ºC and 10 s-1.

Simulación de un tratamiento térmico mediante elementos finitos

Fri, 10 May 2013 13:04:34 GMT

Title: Simulación de un tratamiento térmico mediante elementos finitos Authors: Giménez, Maria; Llobet, Albert; Riera Colom, María Dolores; Prado Pozuelo, José Manuel Abstract: En la industria abundan procesos térmicos o termo-mecánicos durante los cuales se producen distorsiones difíciles de predecir y controlar. Las diferentes velocidades de enfriamiento ocasionadas a lo la rgo de la pieza durante el proceso producen una distribución de fases con volumen específico y propiedades mecánicas diferentes, que generan tensiones internas y dichas distorsiones. Incorporar la evolución microest ructura l a la simulación permitiría definir procesos industriales optimizados. El objetivo principal de este trabajo ha sido incorporar a la simulación las transformaciones de fase y las distorsiones que estas producen . Como aplicación concreta se ha simulado el tratamiento térmico de un componente real . Se ha implementado el modelo de JMAK para determinar la evolución de las transformaciones de fase gobernadas por la difusión y el modelo de Koistinen-Marburger para la transformación martensítica. Para obtener el tiempo de incubación de las transformaciones no isotérm icas y el crecimiento de las propias fases se ha utilizado la Regla de Adición. Los coeficientes de expansión térmica de cada una de las fases han sido obtenidos de la bibliografía. Estos modelos se han incorporado mediante subrutinas de usuario. Los resultados obtenidos hacen concluir que los modelos no siempre describen fielmente las transformaciones de fase . La ferrita y la perlita quedan bastante bien modelizadas, sin embargo, para la bainita, tanto el tiempo de incubación como la fracción transformada no quedan bien descritos.

Friction coefficients and wear rates of different orthodontic archwires in artificial saliva

Thu, 09 May 2013 14:46:28 GMT

Title: Friction coefficients and wear rates of different orthodontic archwires in artificial saliva Authors: Alfonso, M.V.; Espinar, Eduardo; Llamas, José María; Rupérez de Gracia, Elisa; Manero Planella, José María; Barrera, J.M; Solano, E.; Gil Mur, Francisco Javier Abstract: The aim of this paper is to analyze the influence of the nature of the orthodontic archwires on the friction coefficient and wear rate against materials used commonly as brackets (Ti–6Al–4V and 316L Stainless Steel). The mate- rials selected as orthodontic archwires were ASI304 stainless steel, NiTi, Ti, TiMo and NiTiCu. The array archwire’s materials selected presented very similar roughness but different hardness. Materials were chosen from lower and higher hardness degrees than that of the brackets. Wear tests were carried out at in artificial saliva at 37 C. Results show a linear relationship between the hardness of the materials and the friction coefficients. The material that showed lower wear rate was the ASI304 stainless steel. To prevent wear, the wire and the brackets have high hardness values and in the same order of magnitude.

Multifunctional nanocomposite foams based on polypropylene with carbon nanofillers

Thu, 09 May 2013 14:05:52 GMT

Title: Multifunctional nanocomposite foams based on polypropylene with carbon nanofillers Authors: Sousa Pais Antunes, Marcelo de; Gedler, Gabriel; Velasco Perero, José Ignacio Abstract: This work considers the preparation and characterization of polypropylene foams with variable concentrations of graphene and carbon nanofibres, focussing on the influence of the foaming process and the nanofillers on the microstructural and dynamic-mechanical- thermal properties of the foams. Great differences were found in terms of foam morphology depending on the type of foaming process, with foams prepared by physical foaming showing a vertically deformed cell structure, while chemical foams presented an isotropic-like cellular structure. The addition of graphene resulted in foams with higher cell densities and more uniform cellular structures when compared to the ones with nanofibres. All these considerations are of extreme importance, as some of the most promising applications of these polymer foams require a good electromagnetic interference shielding efficiency, which greatly depends on the developed foam morphology.

Shock-free aerofoil/wing design optimisation via morphing technique: leading and trailing edge deformation

Tue, 07 May 2013 14:53:27 GMT

Title: Shock-free aerofoil/wing design optimisation via morphing technique: leading and trailing edge deformation Authors: Lee, D.S.; Srinivas, K.; Periaux, Jacques; Oñate Ibáñez de Navarra, Eugenio Abstract: The paper investigates the drag reduction of aerofoils and wings using a morphing technique which consists of deforming the leading and trailing edges. It is treated as an optimisation procedure using Evolutionary Algorithms. For the purpose, an in house code - Multi-Objective Genetic Algorithm (MOGA) under High Performance Computing (HPC) environment is used. An Euler code with viscous corrections is used to compute the flow. Baseline design is that of RAE5243. Two test cases are considered; the first one considers a morphing aerofoil/wing design via trailing edge deformation (TED) while the second test uses both leading and trailing edge deformations (LTED) to minimise the total drag. Numerical results show that applying morphing technique on existing aerofoil/wing significantly reduces transonic total drag and improves lift on drag (L/D) value when compared to the baseline design.

A strategy case to facilitate the technology transfer between universities-enterprise

Tue, 07 May 2013 13:35:49 GMT

Title: A strategy case to facilitate the technology transfer between universities-enterprise Authors: Sánchez Romero, Montserrat; Gil Espert, Lluís; Segura Vicente, Sonia

Biphasic calcium sulfate dihydrate/iron-modified alpha-tricalcium phosphate bone cement for spinal applications : in vitro study

Tue, 07 May 2013 09:56:44 GMT

Title: Biphasic calcium sulfate dihydrate/iron-modified alpha-tricalcium phosphate bone cement for spinal applications : in vitro study Authors: Vlad, María Daniela; Valle Mendoza, Luis Javier del; Poeata, I.; López López, José; Torres Cámara, Ricardo; Barraco Serra, Marc; Fernández Aguado, Enrique Abstract: In this study, the cytocompatibility of new ‘iron-modified/alpha-tricalcium phosphate (IM/α-TCP) and calcium sulfate dihydrate (CSD)’ bone cement (IM/α-TCP/CSD-BC) intended for spinal applications has been approached. The objective was to investigate by direct-contact osteoblast-like cell cultures (from 1 to 14 days) the in vitro cell adhesion, proliferation, morphology and cytoskeleton organization of MG-63 cells seeded onto the new cements. The results were as follows: (a) quantitative MTT-assay and scanning electron microscopy (SEM) showed that cell adhesion, proliferation and viability were not affected with time by the presence of iron in the cements; (b) double immunofluorescent labeling of F-actin and α-tubulin showed a dynamic interaction between the cell and its porous substrates sustaining the locomotion phenomenon on the cements’ surface, which favored the colonization, and confirming the biocompatibility of the experimental cements; (c) SEM-cell morphology and cytoskeleton observations also evidenced that MG-63 cells were able to adhere, to spread and to attain normal morphology on the new IM/α-TCP/CSD-BC which offered favorable substratum properties for osteoblast-like cells proliferation and differentiation in vitro. The results showed that these new iron-modified cement-like biomaterials have cytocompatible features of interest not only as possible spinal cancellous bone replacement biomaterial but also as bone tissue engineering scaffolds. Description: Premi del "National University Research Council" del Ministeri d'Educació i Recerca de Romania, a autors romanesos per l'impacte de la seva recerca.

Osteogenic biphasic calcium sulphate dihydrate/iron-modified alpha-tricalcium phosphate bone cement for spinal applications : in vivo study

Tue, 07 May 2013 09:39:32 GMT

Title: Osteogenic biphasic calcium sulphate dihydrate/iron-modified alpha-tricalcium phosphate bone cement for spinal applications : in vivo study Authors: Vlad, María Daniela; Sindilar, E.V.; Mariñoso, Maria Lluïsa; Poeata, I.; Torres Cámara, Ricardo; López López, José; Barraco Serra, Marc; Fernández Aguado, Enrique Abstract: In this study, the biocompatibility and the osteogenic features of a new iron-modified α-tricalcium phosphate (IM/α-TCP) and calcium sulphate dihydrate (CSD) biphasic cement (IM/α-TCP/CSD-BC) have been investigated in terms of the in vivo cement resorption, bone tissue formation and host tissue response on sheep animal model. Histological evaluation performed on undecalcified cement–bone specimens assessed the in vivo behaviour. It has been shown that the new IM/α-TCP/CSD-BC has the ability to produce firm bone binding in vivo (i.e. bioactivity). Qualitative histology proved cement biocompatibility, osteoconduction and favourable resorption, mainly through a macrophage-mediated mechanism. The results showed that the new cements have biocompatible and osteogenic features of interest as possible cancellous bone replacement biomaterial for minimally invasive spinal surgery applications. Description: Premi del "National University Research Council" del Ministeri d'Educació i Recerca de Romania, a autors romanesos per l'impacte de la seva recerca.