http://hdl.handle.net/2117/218 2013-06-18T06:32:10Z http://hdl.handle.net/2117/16259 Title: Rehabilitación energética de edificios escolares en clima mediterráneo: caso de estudio, Barcelona Authors: Bosch González, Montserrat; Rodríguez Cantalapiedra, Inma; Álvarez del Castillo, Javier Abstract: necesidad de reducir el consumo energético se hace cada día más evidente, especialmente en Europa debido a su situación de dependencia energética de países externos a la Unión y también por razones relacionadas con el impacto ambiental y las emisiones asociadas. En este contexto, la rehabilitación energética de edificios es una línea de trabajo prioritaria que actúa sobre el parque edificado, y los edificios públicos deben ser un modelo o ejemplo para impulsar este tipo de actuaciones. Los centros docentes, con un potencial de ahorro muy importante y con unos consumos energéticos asociados básicamente a dos grandes conceptos, la iluminación y la climatización, pueden considerarse como un laboratorio de investigación en cuanto a eficiencia energética. A partir de las experiencias adquiridas durante más de 10 años se ha desarrollado una metodología de análisis para la intervención en edificios docentes en Barcelona con los siguientes objetivos: definir los indicadores estratégicos para identificar las oportunidades de ahorro, evaluar las posibles medidas de reducción de consumos a partir de la limitación de la demanda, analizar y dar contenido al papel de cada uno de los actores que intervienen en las estrategias de uso y gestión de los edificios escolares y establecer los criterios que deben considerarse para realizar las futuras intervenciones de rehabilitación energética. El método, como manera de pensar ordenadamente, ha de permitir optimizar los recursos y descubrir les rutas de trabajo que nos conduzcan al objetivo final: reducir el consumo energético del parque edificado http://hdl.handle.net/2117/19528 Title: Dielectric, thermal, and mechanical properties of acrylonitrile butadiene styrene reinforced with used tires Authors: Mujal Rosas, Ramón María; Òrrit Prat, Jordi; Ramis Juan, Xavier; Marín Genescá, Marcos; Rahhali, Ahmed Abstract: Mass production of tires as well as their storage or elimination is a real environmental problem. Various methods for recycling of tires are currently used, such as mechanical grinding, which separates vulcanized rubber, steel, and fibers from tires. Rubber is, then, used in several industrial applications such as flooring, insulations, and footwear. This paper focuses on a new application for old used tires (ground tire rubber, GTR). Tire dust and acrylonitrile butadiene styrene (ABS) have been mixed, and the maximum accepted concentration of GTR can be attained while keeping dielectric, thermal, and mechanical properties within acceptable limits, and therefore their possible industrial application will be in manufacturing of, for example, dielectrics for capacitors, low-voltage electric fences or electrical cable pipes, and trays. Actually, tire dust with particle sizes <700 μm has been classified into three different groups depending on the particle sizes (p < 200, 200< p < 500, and p > 500 μm). Afterward, ABS has been mixed with different concentrations of GTR, i.e., 5%, 10%, 20%, 50% and 70%, to establish its properties through thermal, mechanical, and dielectric tests. Finally, the fracture surfaces of the composite samples have been evaluated by using scanning electron microscopy. Description: Cop. 2012 Wiley Periodicals, Inc. Adv Polym Techn 32: E399–E415, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/adv.21287 2013-06-07T10:39:39Z http://hdl.handle.net/2117/19526 Title: Influence of the isothermal cure temperature on the nanostructure and thermal properties of an epoxy layered silicate nanocomposite Authors: Shiravand, Fatemeh; Hutchinson, John M.; Calventus Solé, Yolanda Abstract: The cure kinetics of triglycidyl p-amino phenol (TGAP) epoxy resin with a diamine (4,4-diamino diphenyl sulphone [DDS]), reinforced with montmorillonite (MMT), has been studied by differential scanning calorimetry. The isothermal cure reaction consists of two parts: a rapid intra-gallery reaction, attributed to homopolymerization of the TGAP catalyzed by the MMT and the extra-gallery cross-linking reaction of the TGAP with the DDS. Increasing cure temperature promotes the intra-gallery reaction, which should promote an exfoliated nanostructure; this is confirmed by transmission electron microscopy. These results indicate that this system (TGAP/DDS/MMT) is an excellent candidate for achieving exfoliated polymer-layered silicate nanocomposites and identifies a protocol for optimizing the degree of exfoliation. 2013-06-06T14:08:13Z http://hdl.handle.net/2117/19525 Title: Intra- and extra-gallery reactions in tri-functional epoxy polymer layered silicate nanocomposites Authors: Hutchinson, John M.; Shiravand, Fatemeh; Calventus Solé, Yolanda Abstract: Achieving a high degree of exfoliation in epoxy-based polymer layered silicate (PLS) nanocomposites is crucial to their successful industrial application, but has hitherto proved elusive. In this work, a system is presented which shows significant promise in this respect. The isothermal cure of PLS nanocomposites based upon a tri-functional epoxy resin (TGAP) has been studied by DSC, and displays two exothermic peaks. The first peak, very rapid, relates to a homopolymerization reaction within the intra-gallery regions, while the second peak reflects the bulk crosslinking reaction. The occurrence of the intra-gallery reaction before the bulk reaction enhances the degree of exfoliation in the cured nanocomposite. Furthermore, pre-conditioning the resin/clay mixture before adding the curing agent and effecting the isothermal cure also allows a greater extent of intra-gallery reaction to occur before the extra-gallery epoxy-amine reaction. Consequently, this system results in a high degree of exfoliation, as revealed by transmission electron microscopy. 2013-06-06T13:37:16Z http://hdl.handle.net/2117/19483 Title: Multiarm star with poly(ethyleneimine) core and poly(epsilon-caprolactone) arms as modifiers of diglycidylether of bisphenol A thermosets cured by 1-methylimidazole Authors: Acebo, Cristina; Fernández Francos, Xavier; Ferrando, Francesc; Serra Albet, Àngels; Salla Tarragó, José María; Ramis Juan, Xavier Abstract: Well-defined multiarm star copolymers, with hyperbranched poly(ethyleneimine) (PEI) as the core and poly(e-caprolactone) (PCL) arms with different degree of polymerization were synthesized by cationic ring-opening polymerization of e-caprolactone from a hyperbranched poly(ethyleneimine) core and used to modify diglycidylether of bisphenol A formulations cured with 1-methylimidazole as anionic initiator. The curing process was studied by dynamic scanning calorimetry (DSC) and FTIR. By rheometry the complex viscosity of the multiarm stars synthesized and the influence of their addition to the reactive mixture was analyzed in detail. The resulting materials were characterized by thermal and mechanical tests. The addition of the multiarm star to the formulation led to homogeneous materials with a slightly toughened fracture in comparison to neat DGEBA thermosets without compromising thermal characteristics. 2013-06-03T08:38:48Z http://hdl.handle.net/2117/19379 Title: Unexpected differences between thermal and photoinitiated cationic curing oa a diglycidyl ether of bisphenol. A modified with a multiarm star poly (styrene)-b-poly (e-caprolactone) polymer Authors: Morancho Llena, José María; Cadenato Matia, Ana María; Ramis Juan, Xavier; Morell, Mireia; Fernández Francos, Xavier; Salla Tarragó, José María; Serra, Àngels Abstract: The effect of adding a multiarm star poly(styrene)-b-poly("-caprolactone) polymer on the cationic thermal and photoinitiated curing of diglycidyl ether of bisphenol A was studied. This star-polymer decelerated the thermal curing of diglycidyl ether of bisphenol A and modified the final structure of the epoxy matrix. The photocuring was influenced significantly by the addition of the multiarm star. When the proportion of this modifier added was 5%, much more time was necessary for complete photocuring (160 min at 40ºC). In the presence of 10% of modifier, the degree of photocuring reached was very low (0.196 at 120°C). A subsequent thermal post-curing was necessary to cure completely the system. During photocuring in presence of poly(styrene)-b-poly("-caprolactone), the formation of dormant species, which are reactivated when the temperature increases, takes places. The kinetics of the thermal curing and the photocuring was analyzed using an isoconversional method due to the complexity of the reactive process. Applying this method, it has been confirmed the dependence of activation energy on the degree of conversion. The fracture morphology analyzed by scanning electron microscopy exhibited a second phase originated during photocuring by the presence of the modifier. 2013-05-23T10:48:39Z http://hdl.handle.net/2117/19374 Title: Numerical simulations of energy storage with encapsulated phase change materials. Special emphasis on solid-liquid phase change CFD modelling Authors: Galione Klot, Pedro Andrés; Lehmkuhl Barba, Oriol; Rigola Serrano, Joaquim; Oliva Llena, Asensio; Rodríguez Pérez, Ivette María 2013-05-22T12:51:06Z http://hdl.handle.net/2117/19373 Title: A MILP model to design hybrid wind-photovoltaic isolated rural electrification projects in developing countries Authors: Ferrer Martí, Laia; Doménech Lega, Bruno; García Villoria, Alberto; Pastor Moreno, Rafael Abstract: Electrification systems based on the use of renewable energy sources are a suitable option for providing electricity to isolated communities autonomously. Wind and hybrid wind–photovoltaic (PV) systems are increasingly getting attention. To electrify scattered communities, designs that combine individual systems and microgrids have recently proven advantageous. In this paper we present a mathematical programming model to optimize the design of hybrid wind–PV systems that solves the location of the wind–PV generators and the design of the microgrids, taking into account the demand of the consumption points and the energy potential. The criterion is the minimization of the initial investment cost required to meet the demand. The proposed hybrid model is tested with realistic size instances and results show the instances are efficiently solved. Moreover, the model is applied to real case studies in Peru; obtained results verify that the hybrid model efficiently finds solutions that significantly reduce cost. http://hdl.handle.net/2117/19371 Title: Solution methods for the double-support indeterminacy in human gait Authors: Lugrís, Urbano; Carlín, Jairo; Pàmies Vila, Rosa; Font Llagunes, Josep Maria; Cuadrado, Javier Abstract: There is a growing interest in predicting the gait motion of real subjects under virtual conditions, e.g., to anticipate the result of surgery or to help in the design of prosthetic/ orthotic devices. To this end, the motion parameters can be considered as the design parameters of an optimization problem. In this context, determination of the joint efforts for a given motion is a required step for the subsequent evaluation of cost function and constraints. In the double-support phase of gait, the ground reaction forces include twelve unknowns, rendering the inverse dynamics problem indeterminate if no force plate data are available. In this paper, several methods for solving the inverse dynamics problem of the human gait during the double-support phase, using force plates or not, are presented and compared. 2013-05-22T11:29:50Z http://hdl.handle.net/2117/19361 Title: Improvement of the manufacturing process of abrasive stones for honing Authors: Buj Corral, Irene; Vivancos Calvet, Joan Abstract: In the present work, the mixing process of different components of abrasive stones of cubic boron nitride used for rough honing was studied. Stones are made by the sintering process of abrasive grains, a metallic bond, and a humectant that favors covering of each abrasive grain by the bond. Incorrect mixing of abrasive grains with the bond and humectant can result in stones with nonuniform abrasive grain distribution. As the abrasive stone wears out, grain distribution will vary and modify efficiency of the honing operation. Tin is the metal having the lowest melting point among metals in the bond. By means of a scanning electron microscope and energy-dispersive X-ray microanalysis, tin segregation was discarded, which could have led to abrasive grain segregation. Later, mixing tests of the different components of the stones were performed at different mixing times 2013-05-21T13:10:14Z http://hdl.handle.net/2117/19357 Title: Use of a Low-Mach model on a CFD&HT solver for the elements of an object oriented program to numerically simulate hermetic refrigeration compressors Authors: López Mas, Joan; Lehmkuhl Barba, Oriol; Rigola Serrano, Joaquim; Pérez Segarra, Carlos David Abstract: A powerful object oriented approach for the simulation of generic thermal systems (Damle et al., 2008) is used as a framework to numerically simulate the thermal and fluid behavior of hermetic reciprocating compressors. A physical abstraction of the compressor system provides a vertex-edge graph, defining the elements and the neighborhood relations of the system to be solved. Each one of these resulting elements is modeled in order to be solved by itself by giving their respective boundary conditions. Since each element provides its own solver tool, the coupled system can be solved in an integrated form. Into previous works, an unstructured and parallel object oriented Computational Fluid Dynamics and Heat Transfer code (from now on CFD&HT) for accurate and reliable solving of turbulent industrial flow, called TermoFluids (Lehmkuhl et al., 2007), was used to provide with CFD&HT capability the system elements (López et al., 2010). In this work, a Low-Mach based CFD&HT module (Chiva et al., 2011) implemented within the TermoFluids software has been used solve the fluid domain existing inside the shell of a reciprocating compressor, which is identified as one of the compressor elements in the abstraction stage. This improvement allows us to numerically simulate the recirculation flow inside the shell of a reciprocating compressor, providing detailed information about suction area of the compressor and allowing study of new geometric configurations of such part. Furthermore, in comparison with previously tested CFD&HT modules, the Low-Mach model allows better treatment of the compressibility effects generated at the inner elements of the compressor such as chambers, tubes and undoubtedly the compression chamber. 2013-05-20T15:15:42Z http://hdl.handle.net/2117/19161 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. 2013-05-10T13:22:35Z http://hdl.handle.net/2117/19150 Title: Small-scale characteristics and turbulent statistics of the flow in an external gear pump by time-resolved PIV Authors: Ertürk, S.; Vernet, Anton; Pallarés, J.; Castilla López, Roberto; Raush Alviach, Gustavo Adolfo 2013-05-09T12:44:56Z http://hdl.handle.net/2117/19113 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. 2013-05-07T09:56:44Z http://hdl.handle.net/2117/19112 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. 2013-05-07T09:39:32Z