During the last decades there has been an increase in the generation of solid wastes in the world, in developing countries the situation has been specifically critical since in many cases there is no adequate treatment for the solid waste due to the scarcity of the resources and to the poor conscience of the real situation and possible consequences. This document presents the composting method as a suitable alternative for the treatment of solid waste in developing countries considering that its costs are not so high and that the composition of the solid waste is mainly organic. The analysis was based on a current literature review and on the study of some cases of composting projects, according to the results an operational guideline for the development of composting projects in developing countries was proposed. The guideline is composed of two main cores: the planning system and the evaluation system. The planning system supports the development of a composting project and the evaluation system is a base for the comparison of performance between different future cases.

Engineered barriers are used in the containment of hazardous materials and are usually a composite of compacted clayey soil and a synthetic membrane. Containment elements such as landfill liners should be designed to control or prevent leachate migration or groundwater ingress. Engineering specifications for a compacted clay liner are based mainly in a hydraulic conductivity less than 10-9 m/s and the need for stability during construction and operation of the landfill. Sandbentonite mixtures are often used as a barrier material. The addition of relatively small amounts of bentonite (5-15%) can improve the performance of a granular material providing both a low permeability and an enhanced mechanical stability. However not all the possible compaction conditions produce a low permeability and mechanically stable material. Changes in water content after compaction can cause swelling or collapse depending on the stress and suction conditions before the water content change occurs. A laboratory investigation of the swelling-collapse behaviour of compacted mixtures of Sand-bentonite has been undertaken. Compaction and suction characteristics were established. The suction and volume change characteristics were investigated through a series of oedometer tests. The central part of the experimental programme focused on the detailed investigation of the processes of swelling and collapse during controlled wetting.To do this, a significant number of modifications were required to the existing apparatus. Fabric studies including Environmental Scanning Electron Microscopy and Mercury Intrusion Porosimetry were also undertaken. Intrinsic behaviour and the relationship between suction and water content were comprehensively studied. A parametric study of the influence of bentonite content and sand grading was also undertaken. The results are presented and analysed. Recommendations for future research are made.

Carbon Capture and Storage (CCS) is an emerging technology designed to tackle climate change by making processes more sustainable. This work gives a technical review of the current status of this process in order to compare it with the production of biochar. The latter is a carbon-rich material obtained when biomass is heated in the absence of oxygen. Although this production technique, which is called pyrolysis, has been known for centuries, there is little information regarding its process at an industrial level. As a result, this dissertation presents a study of the feasibility of biochar production as a means of carbon capture and storage. In other words, this research generates an approach to provide a preliminary estimate of the potential of large-scale biochar production to reduce atmospheric CO2. In this context, it is important to consider that pyrolysis-based biochar could be valuable in terms of soil improvement, crop yield increase, bioenergy generation and greenhouse gas (GHG) offsets. In this perspective, there are two categories of pyrolysis: fast and slow. Fast pyrolysis produces biochar in a matter of seconds, whereas slow pyrolysis produces a higher conversion to biochar but in a matter of hours. Generally speaking, the pyrolysis-based process is considered to be carbon-negative, because biochar production could reduce the amount of carbon in the atmosphere. In terms of the data analysis, several factors were considered and some assumptions were made. These assumptions are based on the literature because biochar production is not yet available at a commercial scale. According to the results, the cost to capture a tonne of carbon dioxide is $6.47 and $32.49 for fast and slow pyrolysis respectively. Therefore, although it is not a profitable technology, it could be cost competitive compared with CCS projects.

Managing and arbitrating behaviours, processes and components in multilayered cognitive architectures when a huge amount of environmental variables are changing continuously with increasing complexity, ensue in a very comprehensive task. The presented framework proposes an hybrid cognitive architecture that relies on subsumption theory and includes some important extensions. These extensions can be condensed in inclusion of learning capabilities through bio-inspired reinforcement machine learning systems, an evolutionary mechanism based on gene expression programming to self-configure the behaviour arbitration between layers, a co-evolutionary mechanism to evolve behaviour repertories in a parallel fashion and finally, an aggregation mechanism to combine the learning algorithms outputs to improve the learning quality and increase the robustness and fault tolerance ability of the cognitive agent. The proposed architecture was proved in an animat environment using a multi-agent platform where several learning capabilities and emergent properties for self-configuring internal agent’s architecture arise.

The mechanisms and pathways by which nitrogen in its various forms is removed from waste stabilization ponds (WSP) have been a subject of much debate. In order to improve current understanding of the dynamics of inorganic and organic nitrogen removal in WSP systems, a study using stable nitrogen isotopes (15N) was undertaken on an experimental pilot-scale WSP system at Esholt Wastewater Treatment Works (Bradford, UK) in summer 2005 and 2006. A primary maturation pond was spiked with 15N-labelled ammonia (15NH4Cl) and 15N-labelled algae (Chlorella vulgaris) to track nitrogen transformations and removal associated with ammonia volatilization, nitrification, and algal uptake and its subsequent sedimentation and retention/hydrolysis in the sludge layer. Stable isotope analysis of 15N, in conjunction with performance indicators, revealed that total nitrogen is poorly removed (? 8%) but ammonium nitrogen removal is very good in summer (effluent concentration <2 mg NH4 + -N/L). The nitrogen cycle in maturation ponds is dominated by biological uptake as ammonium nitrogen is rapidly transformed into algal biomass as suspended organic nitrogen which then either leaves in the pond effluent or is sedimented as dead cells. Ammonia removal by volatilization makes little or no contribution to nitrogen removal and biological nitrate uptake prevents classical nitrification. Thus algal uptake of ammonium and subsequent sedimentation and retention in the sludge layer, after parti al ammonification of the algal organic nitrogen, appears to be the dominant mechanism for permanent nitrogen removal in maturation ponds during warm summer months in England.

Abstract: The synthesis of nanostructures has attracted much interest due to their advanced properties compared to their bulk material. Zinc Oxide (ZnO) has gained substantial interest in the research community due to its large exciton binding energy (60 meV). ZnO is a semiconductor with several favorable properties like a good transparency in the visible region, and a wide band gap of 3.37 eV. Those properties are already used in many emerging applications as chemical sensors, nano laser, and transistors. Due to its wurtzite crystal structure ZnO readily grows to elongated nanoparticles such as nanorods or nanowires. Elongated nanostructures are promising due to precise electron transport in one direction. Special attention has been devoted to the realization of transparent conductive oxides (TCOs) for optoelectronic devices such as solar cells and displays. The first part of this thesis is dedicated to the comparison of the synthesis of ZnO nanorods in a three-neck flask to solvothermal method. In order to investigate the effects of various reaction parameters on the structural and optical properties in the solvothermal method, different temperatures, volumes of solvent and reaction time were selected. The second part addresses the tailoring of the microstructure and electrical properties of ZnO nanorods modified with aluminum and indium, respectively. Finally, doped ZnO nanorods thin films prepared on glass substrate by drop casting method were investigated. This thesis provides first experimental work for transparent conductive zinc oxide prepared by solvothermal synthesis and highlights possibilities and boundaries for introduction of dopants in ZnO nanorods. Resumen: La síntesis de nanoestructuras ha atraído mucho interés debido a sus excelentes propiedades en comparación con su material a granel. El óxido de zinc (ZnO) ha ganado un interés sustancial en la comunidad de investigación debido a su gran energía de ligadura (60 meV). ZnO es un semiconductor con varias propiedades favorables, así como una buena transparencia en la región visible, y una amplia brecha de banda de 3,37 eV. Esas propiedades ya se utilizan en muchas aplicaciones emergentes como sensores químicos, nano láser y transistores. Debido a su estructura de cristal de wurtzita, ZnO se desarrolla fácilmente a nanopartículas alargadas como nanorods o nanocables. Las nanoestructuras alargadas son prometedoras debido al transporte preciso de electrones en una dirección. Se ha dedicado especial atención a la realización de óxidos conductores transparentes (TCO) para dispositivos optoelectrónicos como células solares y pantallas. La primera parte de esta tesis está dedicada a la comparación de la síntesis de nanorods de ZnO en un matraz de tres bocas versus un método solvotermal. Con el fin de investigar los efectos de diversos parámetros de reacción sobre las propiedades estructurales y ópticas en el método solvotermal, se seleccionaron diferentes temperaturas, volúmenes de disolvente y tiempo de reacción. La segunda parte aborda la adaptación de la microestructura y las propiedades eléctricas de los nanorods de ZnO modificadas con aluminio e indio, respectivamente. Finalmente, se investigaron las películas finas de nanorods modificadas y preparadas sobre sustrato de vidrio mediante el método de moldeo a gotas. Esta tesis proporciona el primer trabajo experimental para óxido de zinc como conductor transparente preparado por síntesis solvotérmica y resalta las posibilidades y los límites para la introducción de dopantes en nanorods de ZnO.

Listados y tablas en las que se muestra el resultado del arbitraje internacional que se encargó de vigilar y estudiar el desarrollo de la construcción del ferrocarril de Antioquia. El documento está escrito en francés.

Recent projections estimate that the Netherlands needs circa 33 GW of offshore wind capacity in the North Sea to meet the goals of the Paris Agreement. To this end, the Dutch government has very ambitious plans to create new wind sites far from shore and integrate that power generation to the high-voltage power grid in the next years. Due to the challenges of connecting future massive amounts of offshore wind power into the grid TenneT operates it becomes urgent to investigate new alternatives for this purpose. A grid topology with transmission capacities above 1 GW connecting offshore wind farms at distances close to 100 km in a standardized, modular, and cost-efficient manner is the focus of this thesis. With eight point-to-point HVDC links in operation in Germany and more expected in near future, TenneT TSO is analysing new offshore grid connection concepts to achieve a reliable and secure operation of the infrastructure connecting wind energy both in Germany and the Netherlands. A solution is presented in this thesis report in which new wind farms are connected with 66-kV cables to a centralised platform with a connection capacity of 1050 MW. This platform will utilise HVDC technology based on VSC conversion techniques and MMC topology. It is expected that the 66-kV cables will not be connected to a single busbar through paralleled converter transformer, but that this will be done with at least three converter transformers connected to each other on the valve side but not connected on the 66-kV side. A dynamic performance study of a test network with the novel connection topology developed in PSCAD has been done. Each component of the system was studied to obtain a complete overview and understanding of the overall behaviour. All the associated control loops for the MMC terminals and wind turbines were modelled in detail. Through several simulations based on eight cases and scenarios the performance of the offshore 66-kV ac grid and the MMC-HVDC link using the control schemes of MMC converters as in a typical grid connection topology for OWFs was assessed. Proyecciones recientes estiman que los Países Bajos necesitan alrededor de 33 GW de capacidad eólica marina en el Mar del Norte para cumplir los objetivos del Acuerdo de París. Para este fin, el gobierno holandés tiene planes muy ambiciosos de crear nuevas plantas eólicas lejos de la costa e integrar esa generación de energía a la red eléctrica de alto voltaje en los próximos años. Debido a los desafíos de conectar cantidades masivas de energía eólica marina a la red que opera TenneT en el futuro, es urgente investigar nuevas alternativas para este propósito. El objetivo de esta tesis es estudiar una nueva topología de red con capacidades de transmisión por encima de 1 GW que conecte parques eólicos marinos a distancias cercanas a 100 km de manera estandarizada, modular y rentable. Con ocho enlaces HVDC punto a punto en operación en Alemania y más esperados en el futuro cercano, TenneT TSO está analizando nuevos conceptos de conexión a la red en el mar para lograr una operación confiable y segura de la infraestructura que conecta la energía eólica tanto en Alemania como en los Países Bajos. En este reporte de tesis se presenta una solución en la que los nuevos parques eólicos están conectados con cables de 66 kV a una plataforma centralizada con una capacidad de conexión de 1050 MW. Esta plataforma utilizará tecnología HVDC basada en las técnicas de conversión VSC con topología MMC. Se espera que los cables de 66 kV no se conecten a un solo punto eléctrico a través de transformadores convertidores en paralelo, sino que esto se hará con al menos tres transformadores convertidores conectados entre sí en el lado del convertidor, pero no en el lado de 66 kV. En este documento se presentan los resultados de un estudio dinámico de una red de prueba con la nueva topología de conexión desarrollada en PSCAD. Cada componente del sistema se estudió para obtener una visión general completa y una comprensión del comportamiento de toda la red. Todos los lazos de control de las estaciones convertidoras MMC y las turbinas eólicas se modelaron en detalle. A través de varias simulaciones basadas en ocho casos y escenarios se evaluó el comportamiento de la red de ac de 66 kV en alta mar y el enlace MMC-HVDC utilizando los esquemas actuales de control de los convertidores MMC de las topologías típicas de conexión de red para granjas eólicas marinas.

Modern data acquisition techniques such as Global positioning system (GPS), Radio-frequency identification (RFID) and mobile phones have resulted in the collection of huge amounts of data in the form of trajectories during the past years. Popularity of these technologies and ubiquity of mobile devices seem to indicate that the amount of spatio-temporal data will increase at accelerated rates in the future. Many previous studies have focused on efficient techniques to store and query trajectory databases. Early approaches to recovering information from this kind of data include single predicate range and nearest neighbour queries. However, they are unable to capture collective behaviour and correlations among moving objects. Recently, a new interest for querying patterns capturing ‘group’ or ‘common’ behaviours have emerged. An example of this type of pattern are moving flocks. These are defined as groups of moving objects that move together (within a predefined distance to each other) for a certain continuous period of time. Current algorithms to discover moving flock patterns report problems in scalability and the way the discovered patterns are reported. The field of frequent pattern mining has faced similar problems during the past decade, and has sought to provided efficient and scalable techniques which successfully deal with those issues. This research proposes a framework which integrates techniques for clustering, pattern mining detection, postprocessing and visualization in order to discover and analyse moving flock patterns in large trajectory datasets. The proposed framework was tested and compared with a current method (BFE algorithm). Synthetic datasets simulating trajectories generated by large number of moving objects were used to test the scalability of the framework. Real datasets from different contexts and characteristics were used to assess the performance and analyse the discovered patterns. The framework shows to be efficient, scalable and modular. This research shows that moving flock patterns can be generalized as frequent patterns and state-of-the-art algorithms for frequent pattern mining can be used to detect the moving flock patterns. This research develops preliminary visualization of the most relevant findings. Appropriate interpretation of the results demands further analysis in order to display the most relevant information.

El sistema de aumentación en tierra GBAS permite mejorar el rendimiento de cualquier sistema de navegación por satélite, o GNSS, permitiendo proveer operaciones de precisión en aproximación y aterrizaje hasta la categoría CAT I para aeronaves civiles. El equipo a bordo de la aeronave confía en la validez y exactitud de la información suministrada por la estación GBAS para así calcular sus propios Niveles de Protección (PL). Por tanto, la estación GBAS es completamente responsable de evaluar los y asegurar los niveles de integridad de la señal que recibe, en cumplimiento con los requerimientos establecidos. De lo contrario, una notificación o mensaje ha de ser enviado por la estación GBAS a las aeronaves informando de esta situación. El error de posicionamiento de satélite debido a efemérides es una falla en la cual la ver- dadera posición del satélite no se corresponde con aquella calculada por las aeronaves. Pese al hecho de que la probabilidad de tales eventos es baja, y que normalmente cuando se sucede su magnitud no es lo suficientemente considerable para tener un impacto significativo en el posicionamiento, podría ocurrir que una combinación de factores diera lugar a una amenaza real a la integridad, y a potenciales errores en el posicionamiento. Este reporte se centra en el tipo de error de orbitas B, en el cual la discordancia entre la posición emitida por satélite y la verdadera es una consecuencia directa de un error en la información contenida en las efemérides. Trabajos previos han demostrado satisfactorios resultados detectando estas fallas comparando el mensaje de efemérides recibido con respecto a un mensaje previo que ya haya sido validado, implementando una aproximación de orden cero (ZOH), de primer orden (FOH) y de segundo orden (SOH). El objetivo principal es la implementación de estas aproximaciones, comparar los resultados y elegir un candidato para el monitor de error en orbitas de satélite de tipo B, cumpliendo los requerimientos para aproximaciones y aterrizajes de precisión categoría CAT-I. El siguiente trabajo de grado presentado para optar por el título de Master en Sistemas de Navegación por Satélite en la Escuela Nacional de la Aviación Civil Francesa, ENAC, también presentado como resultado final del trabajo de practicas la Universidad Politécnica de Catalunya, UPC, bajo el marco del Master de Ciencias y Tecnologías Aeroespaciales, detalla el desarrollo e implementación practica de un monitor de orbita de satélite para ser utilizado en aproximaciones de precisión CATI.