A family of stacked central configurations in the planar five-body problem

UPCommons - Jue, 10/26/2017 - 16:36
A family of stacked central configurations in the planar five-body problem Lino Cornelio, J.; Alvarez Ramírez, Martha; Cors Iglesias, Josep Maria We study planar central configurations of the five-body problem where three bodies, (Formula presented.) and (Formula presented.), are collinear and ordered from left to right, while the other two, (Formula presented.) and (Formula presented.), are placed symmetrically with respect to the line containing the three collinear bodies. We prove that when the collinear bodies form an Euler central configuration of the three-body problem with (Formula presented.), there exists a new family, missed by Gidea and Llibre (Celest Mech Dyn Astron 106:89–107, 2010), of stacked five-body central configuration where the segments (Formula presented.) and (Formula presented.) do not intersect. The final publication is available at via
Categorías: Novetats

Geosynchronous inclined orbits for high-latitude communications

UPCommons - Jue, 10/26/2017 - 16:15
Geosynchronous inclined orbits for high-latitude communications Fantino, Elena; Flores Le Roux, Roberto Maurice; Di Carlo, Marilena; Di Salvo, Alessio; Cabot Soler, Elisenda We present and discuss a solution to the growing demand for satellite telecommunication coverage in the high-latitude geographical regions (beyond 55°N), where the signal from geostationary satellites is limited or unavailable. We focus on the dynamical issues associated to the design, the coverage, the maintenance and the disposal of a set of orbits selected for the purpose. Specifically, we identify a group of highly inclined, moderately eccentric geosynchronous orbits derived from the Tundra orbit (geosynchronous, eccentric and critically inclined). Continuous coverage can be guaranteed by a constellation of three satellites in equally spaced planes and suitably phased. By means of a high-precision model of the terrestrial gravity field and the relevant environmental perturbations, we study the evolution of these orbits. The effects of the different perturbations on the ground track (which is more important for coverage than the orbital elements themselves) are isolated and analyzed. The physical model and the numerical setup are optimized with respect to computing time and accuracy. We show that, in order to maintain the ground track unchanged, the key parameters are the orbital period and the argument of perigee. Furthermore, corrections to the right ascension of the ascending node are needed in order to preserve the relative orientation of the orbital planes. A station-keeping strategy that minimizes propellant consumption is then devised, and comparisons are made between the cost of a solution based on impulsive maneuvers and one with continuous thrust. Finally, the issue of end-of-life disposal is discussed. © 2017. This version is made available under the CC-BY-NC-ND 4.0 license
Categorías: Novetats

Architecture for object-oriented programming model

UPCommons - Jue, 10/26/2017 - 15:03
Architecture for object-oriented programming model Markovic, Nikola; González, Rubén; Unsal, Osman Sabri; Valero Cortés, Mateo; Cristal Kestelman, Adrián Current mainstream architectures have ISAs that are not able to maintain all the information provided by the application programmer using a high level programming language. Typically, the information that is lost in compiling to a low-level ISA is related to parallelism and speculation [14]. For example some loops are typically expressed as parallel loops by the programmer but later the processor is not able to determine this level of parallelism; conditional execution might apply control independent execution that at execution time is basically impossible to detect; function and object-level parallelism is lost when code is transformed into a low-level ISA that is oblivious to programmer intentions and high-level programming structures. Object Oriented Programming Languages are arguably the most successful programming medium because they help the programmer to use well-known practices about data distribution through operations related with the associated data. Therefore object oriented models express data/execution locality more naturally and in an efficient manner. Other OO software mechanisms such as derivation and polymorphism further help the programmer to exploit locality better. Once object oriented programs have been compiled then all information about data/execution locality is completely lost in current assembly code (ISA code). Maintaining this information until runtime is crucial to improve locality and security. Finally, Object Oriented Programming Models maintain the idea of memory (data memory) far from the programmer. These are all desirable qualities that is mostly lost in the compilation to a low-level ISA that is oblivious to the Object-Oriented Programming model. This report considers implementing the Object Oriented (OO) Programming Model directly in the hardware to serve as a base to exploit object/level parallelism, speculation and heterogeneous computing. Towards this goal, we present new computer architecture that implements the OO Programming Models. All its hardware structures are objects and its Instruction Set directly utilizes objects hiding totally the notion of memory and other complex hardware structures. It also maintains all high-level programming language information until execution time. This enables efficient extraction of available parallelism in OO serial or parallel code at execution time with minimal compiler support. We will demonstrate the potential of this novel computer architecture through several examples.
Categorías: Novetats

A two-resonance tapping cavity for an optimal light trapping in thin-film solar cells

UPCommons - Jue, 10/26/2017 - 14:57
A two-resonance tapping cavity for an optimal light trapping in thin-film solar cells Liu, Quan; Romero Gómez, Pablo; Mantilla Perez, Paola; Colodrero, Silvia; Toudert, Johann; Martorell Pena, Jordi An optimal photon absorption in thin film photovoltaic technologies can only be reached by effectively trapping the light in the absorber layer provided a considerable portion of the photons is rejected or scattered out of such layer. Here, a new optical cavity is proposed that can be made to have a resonant character at two different nonharmonic frequencies when adjusting the materials or geometry configurations of the partially transmitting cavity layers. Specific configurations are found where a reminiscence of such two fundamental resonances coexists leading to a broadband light trapping. When a PTB7-Th:PC71BM organic cell is integrated within such cavity, a power conversion efficiency of 11.1% is measured. This study also demonstrates that when materials alternative to organics are used in the photoactive cell layer, a similar cavity can be implemented to also obtain the largest light absorption possible. Indeed, when it is applied to perovskite cells, an external quantum efficiency is predicted that closely matches its corresponding internal one for a broad wavelength range. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.
Categorías: Novetats

Metal additive manufacturing: process, conception and post-treatments

UPCommons - Mar, 10/24/2017 - 21:20
Metal additive manufacturing: process, conception and post-treatments Briantais, Lucas This research project is a global study of the metal additive manufacturing from the optimization of the design phase to the improvement of the final state of the parts with finishing treatments and passing by the adjustment of the production process. It starts with a state of art of the technologies, materials and industrial projects leading to focus on the laser melting of a metallic powder bed. The study of the manufacturing process has been realised focusing on the laser’s parameters: its speed and power. The optimization has been made with the objective of improving the surface state of the parts as long as the production was concerning dental implants in Cobalt-Chromium alloy. The design phase has been focused on with the topological optimization method applied to a suspension’s triangle in stainless steel. This method leading to a reduction of the mass and/or gain of stiffness of the part is used a lot with the additive manufacturing as long as it permits complex geometries. It although has to be linked to real tests to get information like the mechanical characteristics necessary for the simulation and to validate or not the resistance of the new geometry. The improvement of the final state of the parts can be related to the surface aspect with the shot peening process but although to the internal state of the part with post heat treatments. Here various heat treatments have been realised on a stainless steel, an aluminium alloy and a Nickel based superalloy to reduce the internal residual stresses and improve the homogeneity of the parts. Different macro and microscopic characterisations have been realised to validate or not the effect of the treatments on the quality of the samples to avoid their deformation and break and to try to approach the characteristics of a part issued from a more classical metal manufacturing process
Categorías: Novetats

Numerical resolution of heat and mass transfer phenomena. Application to the analysis of heat loss by convection in a flat solar collector

UPCommons - Mar, 10/24/2017 - 21:15
Numerical resolution of heat and mass transfer phenomena. Application to the analysis of heat loss by convection in a flat solar collector Galleguillos Ketterer, Cristobal This work is denominated Numerical resolution of heat and mass transfer phenomena. Application to the analysis of heat loss by convection in a flat solar collector. It is divided into eight chapters and four annexes. Chapter 1 presents the objectives, scope, and exclusions of the work. Chapter 2 is dedicated to the analysis of heat conduction in solids, while Chapter 3 covers the various methodologies of resolution of the Convection-Diffusion Equation. An introduction to the numerical resolution of the Navier Stokes equations is presented in Chapter 5. The experimental work on the flat solar collector and its results are presented in Chapter 6. The final conclusions are presented in Chapter 7 and the bibliography that was used for the development of this paper is presented in Chapter 8. In addition, three annexes are presented, Annexes A, B, and C which present the computational codes developed. Annex D presents the daily reports of the experimental part for the selected days.
Categorías: Novetats

Síntesis y caracterización de poliuretanos derivados de la glucosa para aplicaciones como recubrimientos sostenibles

UPCommons - Mar, 10/24/2017 - 21:11
Síntesis y caracterización de poliuretanos derivados de la glucosa para aplicaciones como recubrimientos sostenibles Garcia Mestre, Mónica En este proyecto se han sintetizado poliuretanos segmentados de 1,4-butanodiol y diisocianato de hexametileno empleando como segmento “flexible” un poliéster bicíclico derivado de la glucosa y se ha puesto de manifiesto el efecto crítico de la humedad sobre la composición y el peso molecular de los polímeros que se obtienen. La caracterización de los compuestos se realizó mediante los siguientes métodos: resonancia magnética nuclear para la determinación de la composición y la microestructura, cromatografía de permeabilidad en gel para la estimación del peso molecular, calorimetría diferencial de barrido con el fin de conocer el comportamiento térmico incluyendo la temperatura de transición vítrea, y análisis termogravimétrico para la evaluación de la estabilidad térmica y determinación de las temperaturas de descomposición. Los nuevos poliuretanos sintetizados son más sostenibles y presentan estabilidad térmica, temperatura de transición vítrea y biodegradabilidad superiores a los poliuretanos segmentados derivados de la policaprolactona. Estudios subsiguientes complementarios habrán de ratificar el potencial de estos poliuretanos como posibles alternativas a los poliuretanos convencionales empleados en la actualidad.
Categorías: Novetats

Design and simulation of an automated warehouse solution for a dough and pastry factory

UPCommons - Mar, 10/24/2017 - 21:08
Design and simulation of an automated warehouse solution for a dough and pastry factory Pujols Jutgla, David
Categorías: Novetats

Definición de un plan de marketing para una empresa local del sector de la papelería Macma Blocs SL

UPCommons - Mar, 10/24/2017 - 21:06
Definición de un plan de marketing para una empresa local del sector de la papelería Macma Blocs SL Figueras Vall, Andrea
Categorías: Novetats

Simulation Models of Perovskite-based Solar Cell Structures

UPCommons - Mar, 10/24/2017 - 19:49
Simulation Models of Perovskite-based Solar Cell Structures Serra, Daniele
Categorías: Novetats

Electric Vehicles Impact on the Low Voltage Grid

UPCommons - Mar, 10/24/2017 - 19:43
Electric Vehicles Impact on the Low Voltage Grid Fradique Lopes Da Silva, João Pedro
Categorías: Novetats

Policarbonat cicloalifàtic sostenible obtingut a partir de la D-glucosa

UPCommons - Mar, 10/24/2017 - 19:40
Policarbonat cicloalifàtic sostenible obtingut a partir de la D-glucosa Barcons Grau, Ferran En aquest treball s’ha sintetitzat un policarbonat cicloalifàtic amb l’objectiu de substituir el PC de bisfenol A amb un polímer sintetitzat a partir de fonts renovables com la D-glucosa. S’han plantejat dos procediments possibles per aconseguir això, un amb catàlisis enzimàtica i l’altre amb catàlisis mixta. El primer consisteix en una polimerització enzimàtica en dues etapes, una transesterificació en massa i una policondensació en dissolució. El segon es tracta d’una polimerització totalment en massa en dues etapes, la primera mitjançant catàlisis enzimàtica i la segona amb un catalitzador inorgànic. En els dos casos, els polímers obtinguts han tingut pesos moleculars moderats. En el primer cas, el pes molecular mitjà en número ha estat de 1800 g/mol i de 3400 g/mol en el segon. Pel que fa a les propietats tèrmiques, la temperatura de transició vítria en el polímer obtingut per la primera via ha estat de 128,5 ºC i de 137,4 ºC en el segon cas. Per acabar s’ha analitzat l’estabilitat tèrmica d’aquests dos polímers en dues atmosferes diferents, en nitrogen i aire. En els dos casos els resultats han estat molt semblants, essent la temperatura de descomposició a un 5% de massa perduda d’uns 320 ºC, la temperatura de màxima descomposició al voltant dels 390 ºC i el pes romanent als 600 ºC inferior en tots els casos al 5% inicial.
Categorías: Novetats

Energy demand forecasting in smart buildings

UPCommons - Mar, 10/24/2017 - 19:37
Energy demand forecasting in smart buildings Picatoste Ruilope, Álvaro Energy demand forecasting has become a relevant subject in the energy management field. Different techniques are being currently applied to forecast the energy demand for different time horizons and for diverse types of loads. Some of them are based in complex Machine Learning (ML) algorithms, which maps the energy consumption to a set of influence parameters or inputs, such as the historical data consumption, the weather or other variables, making it possible to predict the energy demand. Important management decisions from different stakeholders in the Energy sector are based on these predictions and, therefore, it is important to rigorously assess the performance of these predictive models. A specific methodology is presented in this dissertation through its application over a real-building case-study in which energy demand predictions are being carried out by a ML model. All the steps in the evaluation process are explained and exemplified, including the data gathering, evaluation period selection, data preprocess with special emphasis in the data abnormalities an its relation to the process dynamics and, finally, the data process itself. The accuracy of the model and the main parameters of influence are evaluated through four different metrics and data visualizations, based mainly in box-andwhisker plots. Several anomalies when predicting energy consumption in a disaggregated load (single building) have been found in the study. By removing them the stability of the case-study model is around 88%. The metrics yield a MAPE (Mean Absolute Percentage Error) of 18.05% and a MBPE (Mean Biased Percentage Error) of -4.67%. While being values within the literature range they show a poor accuracy. Nevertheless, there is space for improvement and by retraining, refining and calibrating the model it will be possible to improve its performance. The day of the week, the working calendar and the hour of the day showed to have a strong influence over the error metrics analyzed. Other alernative Machine Learnings methodologies have been applied to the same dataset and their performance have been analyzed. Artificial Neural Network, k-Nearest Neighbors and Random Forest based models have been compared after training with more than 1-year hourly Energy Consumption data and other influence variables. The Random Forest achieved the best accuracy when re-trained, showing a MAPE below 10%. The importance of passing a detailed working calendar to the model, using accurate weather variables forecasts and defining an adequate re-training strategy have been proved to improve model accuracy.
Categorías: Novetats

Solar Thermal Systems for Domestic Water Heating Applications in residential buildings : Efficiency and economic viability analysis of monitored plants.

UPCommons - Mar, 10/24/2017 - 19:30
Solar Thermal Systems for Domestic Water Heating Applications in residential buildings : Efficiency and economic viability analysis of monitored plants. Baddou, Yassine Climate change and energy have become the trend of universal discussions in the recent years. It is true that the use of conventional fossil fuels negatively affects our planet, hence the whole renewable energy movements. However, at the current state, the world still cannot be entirely reliant on renewable energies for its needs. On the other hand, utilizing the maximum renewable energy opportunities would have a positive impact on climate change. Many forms of renewable energy can be exploited, wind energy, tidal energy, sun energy and so on. The most common renewable energy is solar energy, it can be used for various ends (electricity generation by photovoltaic/thermal power plants, domestic water heating…). Governments around the world encourage the use of solar domestic water heating, for it’s simple usage, low maintenance requirements and efficiency of the solar heating systems. The Spanish government approved a law in March of 2006, named “Código Técnico de la Edificación”. This regulation is mandatory, and set the minimum quality requirements that residential buildings must have. One of them forces that new and renovated buildings have to produce part the energy demand for heating water by means of a solar thermal system. The aim of this work is to study a domestic solar water heating system in a residential building, to develop a numerical model based on the f-chart method by William Beckman and John Duffie, in order to predict thermal behavior of the solar system and compare the results with real data collected from the solar system using an energy counter called SunEye. The solar system chosen for this study is located in Terrassa-Barcelona, it provides hot water for a residential building of 17 apartments. The solar system is composed of 8 solar collectors with 17 storage tanks (10 of 100L and 7 of 150). The Data collected from this solar system using SunEye will be downloaded from RDmes company cloud server named OMNILUS. An overview of the 12 monitor plants by this company from an energy, CO2 reduction and money saves point of view will be reviewed.
Categorías: Novetats


UPC OpenCourseware - Lun, 10/23/2017 - 00:00
L'assignatura pretén introduir als estudiants en l'estudi conjunt de la transferència d' energia, matèria i quantitat de moviment. Donar-los a conèixer les lleis bàsiques d'aquests tres fenòmens, íntimament relacionats, per tal que puguin formular els models matemàtics que representen els aspectes fonamentals dels problemes reals dels processos químics. Al finalitzar el curs l'estudiant ha de ser capaç de:
OE1. Aplicar les lleis que regeixen la transferència de quantitat de moviment, energia i matèria i interrelacionar els tres fenòmens.
OE2. Formular models matemàtics complexes que representin sistemes reals tant en estat estacionari com no estacionari.
OE3. Plantejar models per obtenir els coeficients de transport individuals i globals necessaris per a la resolució de problemes reals.
Categorías: Novetats

Grasp prediction with convolutional neural networks

UPCommons - Dom, 10/22/2017 - 22:39
Grasp prediction with convolutional neural networks Lluís Salvadó, Francesc This thesis explores the application of a deep learning computer vision approach for grasp classification in order to improve hand prosthesis control. First, a criterion based on prehensile human hand is adopted and object images from different datasets are labeled to a type of grasp. Then, two different convolutional neural networks architectures using weights from pre-trained models are designed in order to deal with single or fusion streams of information. Next, architectures are trained with color and encoded depth images. Finally, offline and online results for both architectures and type of data are reported. Results show that it is possible to classify objects into grasps without recognizing them or having any knowledge about their dimensions.; Este trabajo explora la aplicación de técnicas de aprendizaje profundo por visión por computador en la clasificación de tipos de asimientos con el objetivo de mejorar el funcionamiento de una prótesis de mano. Inicialmente, se adopta un criterio basado en la prensibilidad de la mano humana para etiquetar imágenes de objetos de diversos datasets con un tipo de asimiento. A continuación, se diseñan dos arquitecturas utilizando pesos de modelos pre-entrenados capaces de manejar uno o dos tipos de información al mismo tiempo. Después, las arquitecturas se entrenan con imágenes de color e imágenes de profundidad previamente codificadas. Finalmente, se muestran los resultados obtenidos por las diversas arquitecturas y los tipos de datos. Se demuestra que es posible clasificar objetos, que no son reconocidos y de los cuales no se tiene ninguna información acerca de sus dimensiones, en distintos tipos de asimientos.; Aquest treball explora l'aplicació de tècniques d'aprenentatge profund per a visió per computador en la classificació de diferents tipus de presa d'objectes per tal de millorar el funcionament d'una pròtesi de mà. Inicialment, s'adopta un criteri basat en la prensibilitat de la mà humana per tal d'etiquetar imatges d'objectes de diversos datasets amb tipus de presa. A continuació, es dissenyen dues arquitectures, les quals utilitzen pesos de models pre-entrenats, capaces de gestionar un o dos tipus d'informació al mateix temps. Després, les arquitectures són entrenades amb imatges de color i imatges de profunditat prèviament codificades. Finalment, es mostren els resultats obtinguts per les diverses arquitectures i els tipus de dades. Es demostra que és possible classificar objectes, que no són reconeguts i dels qual no es té cap informació sobre les seves dimensions, en diferents tipus de preses. Project to be developed in the mobility exchange program at Northeastern University. Details will be defined there.
Categorías: Novetats

Modernización de centro de reproducción Copicentro y empresas afines

UPCommons - Dom, 10/22/2017 - 22:33
Modernización de centro de reproducción Copicentro y empresas afines Cerezo Iglesias, Carlos Copicentro representa a un grup d’empreses familiars dedicades des de fa quasi 30 anys a oferir serveis de copies e impressions a la ciutat de Caracas, Veneçuela. En els últims 10-15 anys Copicentro ha tingut un gran creixement en número d’empleats, botigues, clients i equips de treball. Aquest creixement ha provocat que algunes coses no funcionen correctament y necessitin un canvi per a que la companyia pugui seguir creixent. En aquest projecte es planteja la introducció de 3 eines que ajudin al desenvolupament de l’empresa en certs aspectes: Un sistema de gestió de magatzems, un sistema de gestió d’impressions i un sistema d’emmagatzematge d’arxius en xarxa.; Copicentro representa a un grupo de empresas familiares dedicadas desde hace casi 30 años a ofrecer servicios de copias e impresiones en la ciudad de Caracas, Venezuela. En los últimos 10-15 años Copicentro ha tenido un gran crecimiento en número de empleados, tiendas, clientes y equipos de trabajo. Este crecimiento ha provocado que algunas cosas no funcionen correctamente y necesiten un cambio para que la compañía pueda seguir creciendo. En este proyecto se plantea la introducción de 3 herramientas que ayuden al desempeño de la empresa en distintos ámbitos. Un sistema de gestión de almacenes, un sistema de gestión de impresión y un sistema de almacenamiento de archivos en red.; Copicentro represents a group of family companies which since almost 30 years offer services of copies and prints in the city of Caracas, Venezuela. In the last 10-15 years Copicentro has grown a lot in the number of employees, shops, customers and equipment. This growth has caused some things to not work properly. It’s necessary a change so the company can continue growing. This project proposes the installation of 3 tools which will help the company's performance in different areas. A warehouse management system, a print management system and a network attached storage system.
Categorías: Novetats

Graphite EBSD characterization in compact graphite iron

UPCommons - Vie, 10/20/2017 - 20:24
Graphite EBSD characterization in compact graphite iron Morán Zarza, Fernando This research examines different methods of sample preparation, for microstructural characterization of graphite particles. To this purpose, the graphite particles contained in Compacted Graphite Iron are analyzed by Electron Backscattered Diffraction technique. Knowing the crystal orientation of graphite particles is important to understand how its growth occurs. Until now, many theories have been presented without becoming one predominant over the others (Stefanescu, Alonso, Larrañaga, De la Fuente, & Suarez, 2016). Furthermore, by knowing the orientation of the crystals, the interaction at the interface particle-matrix can be understood more clearly. This will help to better comprehend the properties of the material, thereby improving the design and manufacturing processes for pieces. Four methods have been tested: Traditional sample preparation, Focus Ion Beam (FIB) lithography, ion milling parameters simulation with FIB and brittle fracture. The first two have not yielded any result; while the results obtained in the other two are inconclusive due to lack of repeatability and that they are found in very few particles. Therefore, the study of Broad Ion Beam, which is certainly the most promising of all methods set, remains for future research.
Categorías: Novetats

Definition of new simulation scenarios for comfort and handling evaluation and application in a sensitivity analysis of damper characteristics

UPCommons - Vie, 10/20/2017 - 20:20
Definition of new simulation scenarios for comfort and handling evaluation and application in a sensitivity analysis of damper characteristics Reixach Ferran, Adrià Competition among automotive manufacturers has increased a lot in the recent years. One of the main concerns regarding the suspension design of a vehicle is its ride comfort and handling performance characteristics. This thesis aims to create new methodologies for comfort and handling evaluation as well as to make a brief study regarding the influence that the characteristics of a damper have over the vehicle behaviour. The thesis is divided into two parts. In its first part, this thesis proposes new virtual road scenarios, some of which allow evaluating simultaneously ride comfort and handling performance during a vehicle dynamics simulation. These roads are created as a standard CRG format which can be used by different software in the field of vehicle dynamics. In its second part, a total of five different scenarios are chosen in order to study the differences that two different software and two different tyre models have over the results. Three models are used: Adams Car with FTire, Adams Car with MF-Tyre and CarMaker with MF-Tyre. Also, some metrics are defined for each scenario in order to compare quantitatively the results between these three models. Results have shown important differences regarding the tyre model in the impact scenarios and minor differences regarding the software in all scenarios except for the primary ride, which provides good accuracy using the simplest model: CarMaker with MF-Tyre. This configuration also presents much shorter running simulation time. Basically, the best configuration to carry out the simulation would be Adams Car with FTire model for all scenarios except for the primary ride, in which CarMaker with MF-Tyre model could be used too. Also within the second part, a sensitivity analysis is done. The original spline of the front damper is converted into a bilinear spline defined by six different parameters, which are modified at two different levels: 40% lower and higher than baseline. Then, the five scenarios previously defined are used to study how a certain parameter of the damper spline affects each metric. Apart from confirming the expected results (a low level of damping is needed to improve comfort while a high level of damping is needed to improve handling or road holding), this methodology quantifies and helps finding the optimum compromise between ride comfort and handling performance of a damper.
Categorías: Novetats

Analisis de la posisción de conducción en vehículos del fabricante SEAT

UPCommons - Vie, 10/20/2017 - 20:17
Analisis de la posisción de conducción en vehículos del fabricante SEAT Cervera Pedregosa, Pedro
Categorías: Novetats


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