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Found 7890 page(s)
- Abón Olivera, Guillermo
In this minor thesis, the use of concrete as material for floating wind platforms is proposed as an alternative that can provide, great resistance to corrosion and virtually non maintenance. After selecting the best suitable floating platform type for shallow waters a static analysis is done in order to choose the geometry and dimensions that best fits the needs expressed. Then with the selected model, a dynamic analysis is performed in order to check the platform interaction with waves. Finally a basic description of loads affecting the platform and the displacements and efforts distribution on it is shown.
Dynamic Adaptive Streaming over HTTP Study in Heterogeneous Networks, Estudio sobre Dynamic Adaptive Streaming over HTTP en redes heterogeneas, Estudi sobre Dynamic Adaptive Streaming over HTTP en xarxes heterogènies
- Solivellas Mulet, Guillem Rafel
[ANGLÈS] Video streaming is becoming more and more popular in society, both live and on demand video. Some big companies have designed their own standards for video streaming over HTTP. In this project, we study the standard from MPEG, which is open source, called MPEG-DASH. One of the key features of the streaming of video over HTTP is the adaptation to the network. In this project we will go deep on this, testing how big is the impact of the adaptation and designing an algorithm that adapts the streaming to the network conditions., [CASTELLÀ] Streaming de video se está convirtiendo más y más popular en la sociedad, tanto en directo como bajo demanda de vídeo. Algunas grandes empresas han diseñado sus propias normas para la transmisión de vídeo a través de HTTP. En este proyecto, se estudia el estándar de MPEG, que es de código abierto, llamado MPEG-DASH. Una de las características clave de la transmisión de vídeo a través de HTTP es la adaptación a la red. En este proyecto vamos a profundizar en esto, poniendo a prueba qué tan grande es el impacto de la adaptación y el diseño de un algoritmo que adapta la transmisión a las condiciones de la red., [CATALÀ] Streaming de vídeo s'està convertint més i més popular a la societat, tant en directe com sota demanda de vídeo. Algunes grans empreses han dissenyat els seus propis estàndards per a la transmissió de vídeo a través d'HTTP. En aquest projecte, s'estudia l'estàndard de MPEG, que és de codi obert, anomenat MPEG-DASH. Una de les característiques clau de la transmissió de vídeo a través d'HTTP és l'adaptació a la xarxa. En aquest projecte aprofundirem en això, posant a prova què tan gran és l'impacte de l'adaptació i el disseny d'un algoritme que adapta la transmissió a les condicions de la xarxa.
FSK transceiver implementation by means of reprogramming the FPGA of the USRP, Implementacion De Una modulación FSK Por Medio de la reprogramacion de la FPGA de la USRP, Implementació d'una modulació FSK per mitjà de la reprogramacion de la FPGA de la USRP
- Lax Cortina, Jorge
- Portillo Barrios, íñigo Del
The thesis deals with model-based scalability-oriented design of resource-constrained fractionated satellite networks., [ANGLÈS] Fractionated Satellite Networks are a novel concept in space systems where several satellites cooperate and collaborate by exchanging resources wirelessly in order to obtain an aggregated network capability higher than the sum of the individual capabilities of the different satellites that compose it. In addition, Fractionated Satellite Networks can be easily expanded to extend the objectives of the mission or provide support to a larger number of satellites. Because of this expandable nature of Fractionated Satellite Networks, the concept of scalability is critical on these architectures, as systems that do not scale well present a very poor performance when adding new agents, increasing costs and harming quality of service and stakeholder satisfaction. This thesis presents a model and a framework to analyze scalability on Fractionated Satellite Networks. Our model includes descriptions of the system at the resource, satellite, network and mission level. Connections and resource transfer among nodes are modeled using graphs whereas the study is approached from a resource allocation problem perspective. Two case studies are analyzed in order to show the usefulness of the model. The first one studies the scalability of Federated Satellite Systems (dynamic system) whereas the second one analyzes the scalability of a cluster of nanosatellites that depend on a central node (a static system). Finally, based on the conclusions of the analysis conducted and the nanosatellite-technologies state of the art, some guidelines to design nanosatellites that can be easily integrated in fractionated networks are provided., [CASTELLÀ] Las redes de satélites fraccionados son un innovador concepto en la industria espacial donde varios satélites cooperan y colaboran intercambiando recursos inalámbricamente con el fin de obtener una capacidad agregada en la red superior a la suma de capacidades individuales de cada uno de los satélites que la componen. Además, estas redes pueden ser fácilmente expandidas para ampliar los objetivos de la misión o dar soporte a un mayor número de satélites. Debido a esta naturaleza expandible, el concepto de escalabilidad es crítico en estas arquitecturas, ya que los sistemas que no escalan debidamente presentan un comportamiento muy deficiente al añadir nuevos agentes, aumentando costes y dañando la calidad de servicio y la satisfacción de los stakeholders. Esta tesis presenta un modelo y un marco para analizar la escalabilidad en las redes de satélites fraccionados. Nuestro modelo incluye una descripción del sistema a los niveles de recurso, satélite, red y misión. Las conexiones y la transferencia de recursos entre nodos son modelados empleando grafos, mientras que el estudio se afronta desde la perspectiva de la resolución de un problema de asignación de recursos. Con el fin de mostrar la utilidad del modelo y el framework, dos análisis son presentados. El primero de ellos estudia la escalabilidad de un Federated Satellite System (sistema dinámico) mientras que el segundo de ellos analiza un clúster de nanosatélites que dependen de un nodo central (sistema estático). Finalmente, empleando las conclusiones de los análisis conducidos y el estado del arte de las tecnologías para nanosatélites, ciertas guías de diseño para que los nanosatélites puedan ser integrados en redes fraccionadas fácilmente son proporcionadas., [CATALÀ] Les xarxes de satèl·lits fraccionats són un innovador concepte en la indústria espacial on diversos satèl·lits cooperen i col·laboren intercanviant recursos sense fil amb la finalitat d'obtenir una capacitat agregada a la xarxa superior a la suma de capacitats individuals de cada un dels satèl·lits que la componen. A més, aquestes xarxes poden ser fàcilment expandides per ampliar els objectius de la missió o donar suport a un major nombre de satèl·lits. A causa d'aquesta naturalesa expandible, el concepte d'escalabilitat és crític en aquestes arquitectures, ja que els sistemes que no escalen degudament presenten un comportament molt deficient en afegir nous agents, augmentant costos i danyant la qualitat de servei i la satisfacció dels stakeholders. Aquesta tesi presenta un model i un marc per analitzar la escalabilitat en les xarxes de satèl·lits fraccionats. El nostre model inclou una descripció del sistema als nivells de recurs, satèl·lit, xarxa i missió. Les connexions i la transferència de recursos entre nodes són modelats emprant grafs, mentre que l'estudi s'afronta des de la perspectiva de la resolució d'un problema d'assignació de recursos. Per tal de mostrar la utilitat del model i el framework, dues anàlisis es presenten. El primer d'ells estudia l'escalabilitat d'un Federated Satellite System (sistema dinàmic) mentre que el segon d'ells analitza un clúster de nanosatèl·lits que depenen d'un node central (sistema estàtic). Finalment, emprant les conclusions de les anàlisis conduïts i l'estat de l'art de les tecnologies per nanosatèl·lits, certes guies de disseny perquè els nanosatèl·lits puguin ser integrats en xarxes fraccionades fàcilment són proporcionades.
- Ortiz Alcalá, Lluís
The detection of corrosion in pipelines is an aspect of utmost importance as far as the fluid transportation industry is concerned, and especially if they have a difficult access. As they are installed outdoors or underground, these kilometric conduits are under various weather and natural phenomena, which may damage them causing loses and consequently serious natural disasters. Over the years, the most common way to check the pipelines’ thickness has been thanks to ultrasonic and Foucault currents. The constraint of these techniques is that they only allow examining the thickness just under the probe. Thus, the checking procedure along its entire length becomes a very dull and long process. The problem arises when the access to certain stretches of those pipelines becomes extremely complex, making this control impossible. Upon needing to inspect these pipelines in a precise, quickly and easy way along their length, this control method is rarely used any more. Low frequency guided waves are beginning to be used frequently to perform this task since their detection and location capability of corroded patches is very good. The only drawback that this screening technique presents is that it only gives a rough estimate of the remaining wall thickness. Currently, guided waves are the most powerful method not only to detect inaccessible corroded patches but also to map their remaining thickness precisely. Nowadays, the world of computer science is so immensely vast that there is a large amount of software solutions to perform the same task. The problem ascends when a user needs to complete a specific job and does not know which of the programs at his disposal to choose. Some of the aspects that will prevail in his decision is if the software’s interface is good-looking, the price of software’s license, the memory consumption at the time of performing a task but mainly the time taken to complete the work. The aim of this report is to compare two of the most important programs for finite elements simulations: Abaqus and ANSYS. This analysis was done by applying a signal of 50 kHz and 10 cycles, involved in a Hanning window in a titanium plate of 1 m long and with a thickness of 5 mm. The reason why this study was done by simulating a plate instead of a pipeline, without forgetting the aforementioned, is because it was needed to simulate an easy geometry in order to shorten the time taken to solve the simulation by both software solutions. The conclusions of this work were obtained by analysing which of the software solutions offered the most accurate displacements of a node located one meter far from where the signal was implemented. In case that both were equally precise, what was determinant for us at the time of choosing the best software program was which of both took the highest analysis speed, less time and memory consumption to perform the task., Outgoing
- Masvidal Andreu, Clara
The main objective of this project is to analyse the technical and economic feasibility of installing a large offshore wind farm (over 50 MW) on the coastline of Tarragona, taking as a reference the large offshore parks in the Nordic countries, as the Middelgrunden in Denmark. Although being one of the European countries with European countries with the most on-land wind plants installed to date, Spain currently has no offshore wind farm in operation, and this has been one of the main reasons that have led to the undertaking of this project: to determine if installing an offshore wind farm at the Catalan coastline is feasible or not. To achieve this goal this project has been divided into two parts: the first is the design of the offshore wind farm, taking into account all the existing regulations as well as several technical criteria to make better use of the wind resource. Actually two power wind plants have been designed for two types of wind turbines to be installed. These two wind farms are compared simultaneously for all the economic aspects. The second part provides an economic feasibility analysis of the facilities designed. This includes the determination of capital and maintenance costs of the park, as well as the determination of the revenues from the sale of the energy produced by both offshore wind farms. Along with these, a cost benefit analysis of the project is carried out. A sensitivity analysis for different parameters of the profitability analysis is also done at the end of the economic feasibility analysis. Finally, this project has analysed how the changes in the law concerning economic compensation for the energy produced by the facilities of the special regime affect the profitability of an offshore wind project.
High strength steel fracture: fracture initiation analysis by the essential work of fracture concept
- Torrentallé Dot, Maria
Advanced High Strength Steels (AHSS) are used in the automotive industry in form of thin sheets, to reduce weight and increase crashworthiness. However their moderate ductility can be a disadvantage for their conformation, these type of steels are prone to crack after forming. These cracks normally nucleate from notches or edge irregularities. Therefore knowing their behaviour at fracture is necessary to predict their performance in service. But traditional approaches to measure fracture toughness are not valid for thin sheets. Essential Work of Fracture (EWF) is an experimental methodology that can measure fracture toughness in thin sheets using an energetic approach. In this work two Dual Phase (DP) AHSS steels, DP780 and DP1000, that are vastly used in the automotive industry, are studied. Double Edge Notched Tests (DENT) are simulated by Finite Element Modelling (FEM), aimed at introducing a method to identify fracture initiation using the same EWF energetic approach. This method is experimentally validated by testing it on a notched hole specimen specially designed for this purpose. It will allow to extrapolate known fracture initiation data from DENT specimens to other specimens with the same thickness, notch size and stress triaxiality. Finally several fracture properties are related with the state of stress in the specimens by using two parameters, stress triaxiality and lode parameter.
- Gracia Abilla, Sara
This document contains the results of the energy usage optimization in HEMAV test-bed. It has been developed as part of an internship in HEMAV, a young European company based in Molins de Rei, Barcelona dedicated to make safe civil services with RPAS technology. The main objectives of this study are increase the flight time of the hexacopter by studying the behaviour of different propellers and increasing or decreasing the number of batteries. And, finally, study the influence of performing different paths in the autonomy. First of all, it is proposed to create a data base where after each mission the whole data collected would be downloaded, because, then, this data could be analysed. And doing this, HEMAV would be able to know what the most usual manoeuvres and operations are and they could try to increase their efficiency. The main conclusion extracted from the propellers study is that the material of the propeller does not have a notable effect in terms of thrust. But when looking at the consumption, it can be seen a positive effect, less consumption, when the material is carbon fibre instead of nylon. In addition, during the propellers study it was known that pitch is one of the important factors, smaller propeller pitch means more thrust. But, also, it was known that for bigger propeller pitches the necessary acceleration to change from a lower velocity to a higher velocity is smaller than in the contrary case. After the propellers study, the effect of having more batteries in the platform was analysed and the main conclusion is that there is a point where although more batteries are added, the flight time do not increase more. This point is around the 1246 gr of the propeller test battery, and it coincides for the three propellers. So doubling the battery capacity does not mean doubling the hover flight time. Also, the author realized, in the dynamic test, that the procedure that has to be followed before performing a flight is very large. And that there are a lot of things that should be taken into account, such as sensors implementation, check that everything is safe and works properly, find a place to fly, and check that all is still running before doing the test. Finally, it was verified that the hexacopter consumes a lot when it has to maintain the same position, the same as when there are sudden changes in velocity.
- Lauzurica Gonzalez, Alejandro
In the present thesis a study of the erosion rates that blades from a typical radial inflow turbine suffer because of the ingested flow containing solid particles is presented. The mentioned study has been conducted by carrying out a series of CFD simulations using the software package ANSYS CFX. The obtained results indicate that there are three main surface areas where significant erosion loss occurs. The first of them and by far the most affected part of the turbine is located at the trailing edge of the stator blade, where a relatively great number of impacts with low angles strike the surface. This surface area is found to be affected by a concentration effect, that is, many particles impinging a small surface area. The second but lesser affected part is the leading edge of the suction side of the rotor blade, on which many particles strike many times due to particles being trapped in a vortex area. The third and last surface area which is eroded significantly, but in comparison to the other parts facing much less erosion, is the central part of the pressure side of the rotor blade. Additionally, several influencing factors have been studied to determine their influence on the erosion rate density, such as angular velocity, particle concentration, particle shape and size and blade material. The relation between these factors and the erosion rate density has been determined. Besides, a final study about the compressibility effects that may have been affected the study has been conducted in order to ensure the validity of the simulations of the thesis., Outgoing