Solución para entornos con cobertura esporádica en LTE

Este proyecto surge de la necesidad, cada día más importante, de estar constantemente conectado. Desde los primeros sistemas de telefonía móvil hasta hoy, la conexión de los usuarios a la red ha ido creciendo exponencialmente, pero a la vez se ha ido incrementando lo que se conoce como brecha digital, ya que sigue existiendo un escollo en las conexiones en entornos rurales. Debido a la dispersión de la población, a la orografía y al bajo retorno de la inversión para los operadores, las zonas rurales y de montaña siempre han visto limitada su cobertura y su velocidad. LTE (Long Term Evolution) es un nuevo salto en la evolución de la telefonía móvil, proporcionando diversas ventajas respecto a los sistemas anteriores. Las principales ventajas que proporciona en entornos rurales son que ha sido diseñado para obtener las máximas prestaciones en radios de cobertura de hasta 30 Km, su baja latencia y su escalabilidad espectral. Lo que ayuda a utilizando un menor número de nodos, llegar a cubrir un mayor territorio. A pesar de las mejoras, siguen existiendo puntos de especial interés que será muy difícil que puedan estar cubiertos por LTE y de esta necesidad surge este proyecto. Para ello se ha realizado el estudio previo de la cobertura 2G/3G que existe actualmente en una zona concreta, sobre la que se basa el proyecto. Para llevar a cabo este estudio se han realizado mediciones de los niveles de señal en una ruta de senderismo muy frecuentada en la sierra de Madrid. A continuación, se ha realizado una simulación de cobertura de las diferentes frecuencias de LTE que están utilizando los operadores españoles en su red. Para valorar cual es la que mejores prestaciones proporciona en la zona de estudio. Finalmente se han analizado y simulado dos propuestas para la mejora de la señal recibida en entornos con cobertura esporádica. Ambas propuestas se basan en la utilización de un terminal intermedio, entre el nodo y el terminal sin cobertura, que actuará como repetidor o punto de acceso para el terminal sin cobertura. Para la conexión del terminal intermedio y el terminal sin cobertura se han analizado dos opciones: la utilización del sistema LTE y la utilización de WiFi. Debido principalmente a su mayor propagación de la señal se ha elegido utilizar LTE en la banda de 800 MHz y como terminal intermedio un sistema LTE ya que en las pruebas realizadas demostraba una cobertura mayor con unos mejores niveles de señal que la opción WiFi.Mobile communication systems have limited coverage and throughput in rural and mountain areas due to the dispersion of the population, sparsely populated áreas, the topography and the low deployment of nodes. LTE is the next step in the technical evolution of 2G/3G networks. LTE offers several advantages compared to previous systems in rural environments. The main advantages provided in rural areas are: it is designed for maximum performance in coverage radius up to 30 km, very low latency and flexibility on spectrum bandwidth. Because of these characteristics with fewer nodes, than 3G, you can cover the same area. Despite the LTE improvements, there are points of special interest that will be very difficult to cover. This is the reason for this project, which objective is to extend coverage in rural areas. For this reason, I have completed a preliminary study of the 2G/3G coverage that exists in a particular area. To carry out this study, I have made measurements of signal levels (drive test) in a very popular hiking route in Madrid. Then, I made simulation of coverage for the different frequency bands used for LTE in Spain. To evaluate which is the best performance provided in the study area. Finally I have analyzed and simulated two options to improve the received signal in environments with sporadic coverage. Both options are based on the use of an intermediate terminal between the node and the terminal without coverage, which will act as a repeater or access point for the terminal without coverage. For connecting the intermediate terminal and the terminal without coverage I have analyzed two options: using LTE system and the use of WiFi. Because of their greater signal propagation I have chosen to use LTE in the 800 MHz band and LTE system for the intermediate terminal. The tests showed greater coverage with better signal levels that the WiFi option.Ingeniería Técnica en Sistemas de Telecomunicació

Algoritmos de búsqueda con retroceso para problemas multicriterio

La búsqueda en grafos, con multitud de aplicaciones en el mundo real, ha propiciado el diseño de una gran cantidad de algoritmos centrados en el procesamiento de un único objetivo, magnitud representativa del coste. Sin embargo, un tratamiento realista de estos problemas requiere en muchas ocasiones contemplar diferentes objetivos de modo simultáneo. Además, es habitual que estos objetivos sean antagónicos, de tal modo que la optimización de uno de ellos se traduzca en el empeoramiento de uno o varios de los objetivos restantes. Esto hace que el coste óptimo no sea único, sino que generalmente existe un conjunto de soluciones óptimas cuyas componentes de coste están compensadas entre sí. Esta naturaleza multiobjetivo de los problemas provoca que el rendimiento de los algoritmos empeore de modo considerable, ya que al procesamiento habitual de los nodos generados durante el proceso de búsqueda hay que añadir el tratamiento de vectores de coste (de dimensión igual al número de objetivos considerado) y el manejo de un conjunto de soluciones óptimas (cuyo tamaño en el peor de los casos será exponencial), siendo este tipo de operaciones muy costosas desde el punto de vista de tiempo y memoria. De las dos principales clases de algoritmos exactos multiobjetivo, la correspondiente a un enfoque "best-first" ha sido ampliamente estudiada, dando lugar a una gran cantidad de algoritmos que persiguen reducir la complejidad espacial y temporal del proceso de búsqueda. Asimismo existen numerosas y detalladas comparativas de rendimiento entre estos algoritmos. Sin embargo la clase de algoritmos "depth-first", aún siendo de gran utilidad en la resolución de problemas con grafo de búsqueda en forma de árbol, presentaba un reducido número de propuestas, careciendo además de análisis comparativos entre las mismas. Esta tesis pretende cubrir dicho hueco, realizando un estudio sistemático de algoritmos exactos multiobjetivo de tipo "depth-first. Para ello, por un lado se realiza una caracterización detallada de dichos algoritmos, contribuyendo con nuevos diseños multiobjetivo, variantes de algoritmos para un objetivo que aplican los conceptos de "Frontera de Pareto" y "Punto Ideal" a la cota de expansión empleada en la búsqueda "depth-first". De todos estos nuevos algoritmos se aporta su correspondiente análisis formal. Asimismo se realizan adaptaciones de algoritmos multiobjetivo ya existentes, de tal modo que sean aplicables a árboles infinitos, el principal tipo de problemas usado en el análisis de rendimiento realizado en este trabajo. Por otro lado, en esta tesis se realiza un análisis empírico detallado de los algoritmos mencionados. Para ello en primer lugar se determinan los principales parámetros de rendimiento a tener en cuenta en función de la naturaleza multiobjetivo de los problemas considerados. Concretamente el tiempo de ejecución, en combinación con el tamaño de la cota de expansión, se perfilan como los factores clave de rendimiento. Los resultados obtenidos en las pruebas realizadas presentan a la variante multiobjetivo del algoritmo Branch & Bound como la opción más eficiente para árboles de búsqueda tanto finitos como infinitos, precisando de una cota adicional en este último caso

Proyecto de producción de calor para una calefacción de distrito y proceso de secado de madera aserrada a partir de los residuos forestales de un aserradero en O Corgo

Traballo Fin de Grao en Ciencias. Curso 2016-2017Este presente proyecto ha sido realizado con el fin de aprovechar los recursos forestales producidos en un aserradero en O Corgo y utilizarlos como alimentación a una caldera de biomasa. Se pretende, mediante una red de calor, también llamada “district heating”, dar suministro de Agua Caliente Sanitaria (ACS) y agua caliente de calefacción, a varias viviendas alrededor del aserradero, que actualmente utilizan combustibles fósiles. También, el propio proceso de aserrado de madera, demanda agua caliente para el circuito de calefacción de la cámara de secado, por lo que además se destinará energía térmica para este fin. Por último, parte de la astilla producida y sobrante, se venderá a granel. Para llevar a cabo el proceso, se requiere de la implantación de una nave, la cual se situará junto al aserradero. Las dimensiones serán 33,5 metros de largo y 20 metros de ancho. Las principales actividades del proceso serán: Recepción de los residuos forestales, astillado, almacenamiento de astilla húmeda, proceso de secado, almacenamiento de astilla seca, combustión de la astilla y distribución de agua caliente. Se ha estudiado la demanda térmica para el grupo de viviendas y para la cámara de secado, estableciendo así la cantidad de astilla que es necesaria al día. También se ha evaluado la cantidad de residuos forestales producidos en un día de aserrado. En el presente proyecto también se adjunta el coste de la instalación, la cual asciende a 866.193,61 €. Además se adjunta una evaluación económica justificando la rentabilidad del proyecto. Asimismo se incluyen cálculos realizados, planos de las instalaciones, esquemas, pliego de condiciones y un Estudio de Seguridad y Salud

Adhesive behaviour of carbon fibre reinforced plastic panels manufactured using woven and unidirectional tape after ultraviolet laser surface treatment

This paper describes the results obtained when ultraviolet laser treatment was performed as a surface treatment prior to adhesive bonding for two aeronautical carbon fibre-reinforced plastics based on an epoxy resin prepreg. Different laser processing parameters were employed, and their effect on the surfaces was analysed through morphological characterisation and wettability studies. X-ray photoelectron spectroscopy measurements were performed to determine the cleaning and activation effects of the treatment. The strength of the bonded joint was studied for laser-treated and manually ground samples. Samples processed under the selected laser conditions exhibited better adhesive behaviour than the manually treated samples, thereby suggesting that ultraviolet laser treatment could be used as an alternative method for surface activation of aeronautical composites based on epoxy resin

Influence of Surface Pre-treatments on Laser Welding of Ti6Al4V Alloy

In the present study, Ti6Al4V samples have been welded under conduction regime by means of a high power diode laser. The main objective of the work has been to determine the actual influence of the surface pre-treatments on the laser welding process. Thus, six different pre-treatments were applied to Ti6Al4V samples before performing bead-on-plate and butt welding treatments. The depth, width, microstructure, and microhardness of the different weld zones were deeply analyzed. Grinding, sandblasting, and chemical cleaning pre-treatments lead to welds with the highest depth values, presenting high joint strengths. Treatments based on the application of dark coatings generate welds with lower penetration and worse mechanical properties, specially the graphite-based coating

Achieving superhydrophobic surfaces with tunable roughness on building materials via nanosecond laser texturing of silane/ siloxane coatings

In this work, we employ a versatile laser-based top-down approach that allows to create superhydrophobic and hydrophobic surfaces, with controlled roughness and wetting properties, on marble and potentially other building materials. The process involves two stages: (1) application of an organically modified silica coating to reduce surface energy. (2) Controlled texturing of the coating by ablation using a nanosecond-pulse laser. In general terms, at higher laser fluence (energy per unity of area), the contact angles increased from 110 degrees of the non-textured surface to values around 155 degrees, following a nearly linear correlation with the measured roughness values. Starting from fluence values of 154 J cm-2, the surfaces displayed water repellence (hysteresis <= 10 degrees) and the micrographs showed the formation of sub-micrometric structures on top of the micro-roughness by melting and re-deposition of the coating material, suggesting the formation of a Cassie-Baxter wetting regime. Ablation at lower fluences created a random micro-roughness, leading to static contact angles of 135-145 degrees but no water repellence, which is indicative of a Wenzel wetting regime. At the highest fluence values tested, the increasing trends respect roughness and hydrophobic/water repellent properties are inverted due to the damages suffered by the coating. In terms of durability, the coating demonstrated a good adhesion to the stone surface, maintaining its superhydrophobic properties after repeated cycles of an "adhesive tape test". The sand falling test showed that water repellence is relatively sensitive to abrasion, although the hydrophobic character of the coating is maintained

Noise resistance and shot noise parameters on the study of IGC of aluminium alloys with different heat treatments

In the present paper, the effect of heat treatment on the susceptibility to intergranular corrosion (IGC) of aluminium alloys is analysed. Samples of aluminium alloys AA2024 and AA7075 were first subjected to different heat treatments. Then the susceptibility of these samples to IGC was determined by means of normalized tests, based on the immersion of the samples in an aggressive medium and the subsequent evaluation of the attack, using metallographic analysis. In order to quantity the IGC suffered by the samples, both the degree and the depth of the attacks were measured. In addition, electrochemical noise (EN) signals were recorded during the normalized tests. This technique is especially interesting for the study of corrosion processes of systems with low impedance, such as those faced in this paper, since it does not modify the corrosion potential of the system. Three parameters were used to analyse the EN signals: noise resistance (Rn) and two shot noise parameters, the characteristic charge (q) and the characteristic frequency (fn). Finally, the relationship between the results of the metallographic analysis and those obtained from the analysis of EN signals was established. Unfortunately, a poor correlation between the shot noise parameters and the degree of IGC was found, due to both the high localization and high activities of all systems

Evaluation of pleural effusion sCD26 and DPP-IV as diagnostic biomarkers in lung disease

In this study, we measured ADA and DPP-IV enzymatic activity and sCD26 concentration in 150 pleural effusion (PE) samples and tested for correlations between these and other cellular and biochemical measures. We found that DPP-IV in particular might improve the specificity (but not the sensitivity) of the ADA test for diagnosis of pulmonary tuberculosis, since half of the false ADA positive results in non-tuberculous PE were also DPP-IV positive. A percentage of patients with malignant PE were sCD26 or DPP-IV positive; however, some patients with benign PE also tested positive. As a pattern associated with DPP-IV (but not the CD26 protein) was observed in PE, we searched for a finding that might increase the value of these biomarkers for diagnosis of malignancy. The observed pattern was related to the presence of leukocytes, as indicated by correlations with the cell count, and to a band of 180 kDa, detected by immunoblottingThis research was partially supported by grants PS09-00405 and Research Intensification activity from the Fondo de Investigación Sanitaria (FIS) of the Instituto de Salud Carlos III (Spain) and funding from Xunta de Galicia and FEDER (CN 2011/024). We are grateful to the patients who participated and made the study possibleS

Pitting and intergranular corrosion of Scalmalloy® aluminium alloy additively manufactured by Selective Laser Melting (SLM)

Localized corrosion of Scalmalloy® processed by Selective Laser Melting (SLM) under certified conditions is studied and correlated with the intermetallic particles present in the microstructure. Two types of samples are considered: as-built and heat-treated samples. The heat treatment does not modify the pitting corrosion per- formance. All samples exhibit two groups of pits with different repassivation behaviour. Si-bearing and Fe- bearing phases produce pitting, while Al(Sc,Zr) is not found to be important. The two types of samples are resistant to intergranular corrosion (IGC) according to ASTM G67 thanks to the low content of β phase. However, the heat-treatment slightly increases the IGC-susceptibility.SEM and TEM data were obtained at SC-ICYT University of Cadiz. L. G.R. acknowledges support from the Programme for Attracting Talent of UCA. L.C.C. acknowledges support from UCA and Titania, Ensayos y Proyectos Industriales S.L for her predoctoral position. The authors would also like to acknowledge Dr. Miguel Castillo-Rodríguez (orcid: 0000-0002-5592-0010) for his collaboration in the acquisition of the TEM data, and Titania, Ensayos y Proyectos Industriales S.L. for the support in the achievements of this work

Assessment of the corrosion resistance of self-ordered anodic aluminum oxide (AAO) obtained in tartaric-sulfuric acid (TSA)

The corrosion performance of self-ordered porous anodic aluminum oxide (AAO) has been studied and correlated to its structure. High purity aluminum alloy (> 99.999%) has been anodized using three different conditions: (a) in tartaric-sulfuric electrolyte employing common disordered conditions (TSA), (b) in sulfuric acid applying self-ordering conditions (SA), and (c) in tartaric-sulfuric electrolyte applying self-ordering conditions (TSA-SA). Some samples were post-treated in boiling water with the aim of sealing their pores. The morphology and order of the AAOs were determined by means of scanning electron microscopy and Fast Fourier Transform (FFT), while their corrosion behavior was assessed in 0.59M NaCl employing potentiodynamic polarization tests (LP) and electrochemical impedance spectroscopy (EIS). The evolution of impedance of samples SA and TSA was monitored during 1000 h of immersion in 0.59M NaCl. The three types of samples present similar pore diameter (Dpo) and certain degree of order, although TSA shows the lowest. However, TSA shows smaller interpore distance (Dint), thinner cell wall thickness (tw) and higher pore density (ρpo) and porosity (P) than SA and TSA-SA, which feature very similar values for these structural parameters. The LP curves do not allow to discriminate between samples. SA and TSA-SA have higher impedance than TSA among samples not sealed, probably because a thicker barrier layer forms in samples with self-ordering regime. When sealed, TSA samples show higher impedance than SA and TSA-SA in the medium frequency range because porous membranes with lower order are more easily sealed. All types of AAO, both unsealed and sealed, undergo self-sealing process during the immersion experiments. According to EIS interpretation, TSA porous oxide is self-sealed in a more efficient manner than SA and TSA-SA. These findings imply that self-ordering conditions can enhance the corrosion resistance of AAO