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Persistent high levels of NO2 have severe health effects on population. These are often found in large urban conurbations with high vehicle densities. In Barcelona, with one of the highest vehicle densities in Europe, the two traffic air quality monitoring stations are continuously exceeding the limit values established by the 2008/50/EC Ambient Air Quality Directive. To reduce traffic emissions and associated air pollution levels, Barcelona is applying a series of traffic restrictions that attempt to renew and reduce the amount of circulating vehicles within the city. These include the reduction of private vehicle space in specific areas or urban corridors of the city (superblocks and tactical urbanism) and the implementation of a Low Emission Zone (LEZ) that restricts the entrance of most polluting vehicles in the city. In order to quantify and evaluate the level of effectiveness of the applied restrictions, air quality modelling is presented as a necessary tool to complement the information provided by the air quality monitoring stations. In this sense, the present thesis evaluates the impact that the different restrictions have on the resulting NOx emissions and NO2 concentration levels in Barcelona. To accomplish that, we developed an integrated air quality system composed by the VISUM traffic simulator, the emission model HERMESv3 and the street-scale dispersion model CALIOPE-Urban, which integrates the mesoscale CALIOPE air quality forecast system and the Gaussian dispersion model R-LINE. The thesis first explains the coupling, calibration and validation process of the traffic-emission system. This is followed by an emission sensitivity analysis of typically high uncertainty emission features such as different approaches in regard of vehicle fleet composition, public bus transport implementation, temperature effect or the application of non-exhaust PM sources. We also explore the limitations of the developed macroscopic system by comparing it with a microscopic -highly detailed- approach composed by the microscopic traffic simulator Aimsun Next and the PHEMLight vehicle emission model. Finally, we explain the coupling of the traffic-emission system with the mesoscale CALIOPE and street-scale CALIOPE-Urban air quality systems. In this study, we apply the traffic restrictions previously mentioned in Barcelona to observe their effects in traffic routing, traffic emissions and resulting air quality levels at a resolution of 20 meters. Our results show that the only measures with an overall reduction on NOx emissions are the ones considering the LEZ or a reduction on the traffic demand of -25%. The combination of all strategies with the demand reduction shows the highest NOx emission decrease (-30%) while if traffic demand is kept constant, the computed NOx reductions are of -13%. The strategies limited to restrict the vehicle space on the city show a negligible impact on the overall traffic emissions (+0.1%), although they generate important street-level emission gradients, up to +/-17% in NOx. The impact on NO2 air quality levels follows the same pattern as for emissions. The scenarios comprising the LEZ and the -25% demand reduction show the highest NO2 reductions (-5 to -10 and -10 to -20 ug/m3 in daily average NO2 concentration values). The unique application of traffic measures limiting the vehicle space show limited impacts of +/-5 ug/m3 due to traffic re-routing, as previously commented. Considering the obtained results, the reductions achieved are insufficient to ensure compliant air quality levels, and are very far from reaching the new WHO air quality guideline values. The applied restrictions must be accompanied by a larger decrease in the total number of circulating vehicles throughout the city which could be achieved, for instance, by the application of a congestion charge, or the implementation of local zero emission zones similar to the ones that are currently being deployed in the city of London. La persistente acumulación de altos valores de NO2 presenta serios problemas de salud. Esto ocurre con frecuencia en grandes zonas urbanas con altas densidades de tráfico. En Barcelona, con una de las mayores densidades de vehículos de Europa, las dos estaciones monitoreo de calidad del aire de tráfico exceden de forma continuada los valores limite establecidos por la 2008/50/EC Ambient Air Quality Directive. Para reducir las emisiones de tráfico Barcelona esta aplicando una serie de restricciones al tráfico con el propósito de renovar y reducir la cantidad de vehículos circulante. Estas medidas incluyen la reducción de espacio al vehículo privado en áreas específicas o en corredores de la ciudad (Supermanzanas o urbanismo táctico) y la implementación de una Zona de Bajas Emisiones (ZBE) que restringe la entrada a los vehículos mas contaminantes. Para cuantificar y evaluar el nivel de eficacia de las restricciones mencionadas, la modelización de calidad del aire se presenta como una herramienta necesaria para complementar la información dada por las estaciones de monitoreo de calidad del aire. Esta tesis evalúa el impacto que las diferentes restricciones tienen en los valores de emisión de NOx y de concentración de NO2 en Barcelona. Para ello, hemos desarrollado un sistema de calidad del aire compuesto por el simulador de tráfico VISUM, el modelo de emisiones HERMESv3 y el modelo de dispersión urbana CALIOPE-Urban, que integra el sistema mesoescalar de calidad del aire CALIOPE y el sistema Gaussiano de dispersión R-LINE. En la tesis se detalla el acoplamiento y el proceso de calibración y validación del sistema de tráfico-emisiones. A continuación, se realiza un estudio de sensibilidad valorando diferentes aproximaciones de variables de alta incertidumbre para la estimación de emisiones tales como la composición vehicular, la implementación del transporte público, el efecto de la temperatura o la consideración de fuentes PM no provenientes del gas de escape. También exploramos las limitaciones del sistema macroscópico desarrollado comparándolo con un sistema de alto detalle compuesto por el simulador micro Aimsun Next y el modelo de emisiones vehiculares PHEMLight. Finalmente, explicamos el acoplamiento del sistema tráfico-emisiones con el sistema de calidad del aire mesoescalar CALIOPE y el urbano CALIOPE-Urban que usamos para evaluar las restricciones de tráfico antes mencionadas en Barcelona y observar sus efectos en las rutas de tráfico, emisiones y concentración a una resolución de 20 metros. Los resultados muestran que las únicas medidas con una reducción global de emisiones NOx son las que consideran la ZBE o una reducción de demanda del -25%. La combinación de todas las estrategias con la reducción de demanda muestra las mayores reducciones en NOx (-30%) mientras que si la demanda se mantiene constante las reducciones observadas son del -13%. Las estrategias que se limitan a restringir el espacio del vehículo muestran reducciones negligibles (+0.1%), aunque generan importantes gradientes a nivel de calle que pueden llegar al +/-17% en NOx. El impacto en los valores de concentración de NO2 sigue los mismos patrones que las emisiones. Los escenarios que comprenden la ZBE y la reducción de demanda del -25% muestran las mayores reducciones (-5 a -10 y -10 a -20 ug/m3 de NO2). La consideración de las medidas que únicamente limitan el espacio al vehículo muestran reducciones de NO2 de +/-5 ug/m3 debido a la redistribución de rutas de tráfico. Concluimos que las reducciones obtenidas son insuficientes para asegurar valores de calidad del aire conforme a los límites de la UE, y están muy lejos de llegar a los nuevos valores guía de la OMS. Las restricciones aplicadas deben ir acompañadas por un mayor descenso del total de vehículos circulantes que podría conseguirse, por ejemplo, mediante la aplicación de un peaje de congestión o la implementación de zonas de cero emisiones, similares a las que se están desplegando actualmente en la ciudad de Londres Enginyeria ambiental

Perovskite solar cells are an emerging technology that is evolving rapidly, with power conversion efficiency values that compete with traditional materials such as silicon. In this type of solar cells the photons are absorbed in the perovskite and the charges are extracted using transport materials. By sandwiching the perovskite between a material with and excess of negative (N) or positive (P) charge, one can fabricate a P-i-N or N-i-P structure depending on the deposition order of the materials. Perovskite solar cells have several advantages, mainly the possibility of being very thin thanks to the high absorption coefficient of the perovskite and the wide range of deposition techniques, compatible with industry. From all the deposition techniques, vacuum sublimation stands out due to several advantageous characteristics. This method consists in subliming in high vacuum the required precursor materials for a certain composition, depositing the resulting perovskite onto a substrate. Sublimed perovskite solar cells generally rely on doped organic layers for transporting the electrons and holes photogenerated, which might be chemically unstable and absorb some part of the light, reducing the current generated. This thesis aims to improve vacuum deposited perovskite solar cells, enhancing the stability and performance of the devices. To fulfill this objective, we explore the substitution of the weakest part of the device, the doped transport layers, by implementing the use of transition metal oxides. This type of metal oxides stands out due to the wide range of work functions available and their self-doping, which improves the charge transport thanks to their natural crystal defects. The most interesting metal oxides for the N side are TiO2 and SnO2 due to their adequate energy levels and their proper charge transport. For the P side we chose MoO3 thanks to the possibility of being sublimed and its good hole injection behavior. For these reasons, the thesis is structured as follows: -Chapter 3: Substitution of doped C60 in N-i-P vacuum deposited perovskite solar cells by a TiO2 nanoparticle dispersion, leading to devices with higher efficiencies and better reproducibility. -Chapter 4: Substitution of doped TaTm in P-i-N vacuum deposited perovskite solar cells by MoO3 and then the implementation of this layer in the N-i-P configuration, leading to a design with metal oxides on both contacts. -Chapter 5: Characterization of the P-i-N architecture with MoO3 from chapter 4 under space conditions, which was proven to be very stable and opened the possibility of using perovskite solar cells in high altitude conditions. The substitution of the doped transport layers led to devices with higher power conversion efficiencies (more than 20%, among the highest values for vacuum deposited CH3NH3PbI3 solar cells to date) and more robustness, passing stability tests under space conditions. The work developed in this thesis has opened an interesting field for vacuum deposited perovskite solar cells and changed the main fabrication routes in our laboratory Perovskite solar cells are an emerging technology that is evolving rapidly, with power conversion efficiency values that compete with traditional materials such as silicon. In this type of solar cells the photons are absorbed in the perovskite and the charges are extracted using transport materials. By sandwiching the perovskite between a material with and excess of negative (N) or positive (P) charge, one can fabricate a P-i-N or N-i-P structure depending on the deposition order of the materials. Perovskite solar cells have several advantages, mainly the possibility of being very thin thanks to the high absorption coefficient of the perovskite and the wide range of deposition techniques, compatible with industry. From all the deposition techniques, vacuum sublimation stands out due to several advantageous characteristics. This method consists in subliming in high vacuum the required precursor materials for a certain composition, depositing the resulting perovskite onto a substrate. Sublimed perovskite solar cells generally rely on doped organic layers for transporting the electrons and holes photogenerated, which might be chemically unstable and absorb some part of the light, reducing the current generated. This thesis aims to improve vacuum deposited perovskite solar cells, enhancing the stability and performance of the devices. To fulfill this objective, we explore the substitution of the weakest part of the device, the doped transport layers, by implementing the use of transition metal oxides. This type of metal oxides stands out due to the wide range of work functions available and their self-doping, which improves the charge transport thanks to their natural crystal defects. The most interesting metal oxides for the N side are TiO2 and SnO2 due to their adequate energy levels and their proper charge transport. For the P side we chose MoO3 thanks to the possibility of being sublimed and its good hole injection behavior. For these reasons, the thesis is structured as follows: -Chapter 3: Substitution of doped C60 in N-i-P vacuum deposited perovskite solar cells by a TiO2 nanoparticle dispersion, leading to devices with higher efficiencies and better reproducibility. -Chapter 4: Substitution of doped TaTm in P-i-N vacuum deposited perovskite solar cells by MoO3 and then the implementation of this layer in the N-i-P configuration, leading to a design with metal oxides on both contacts. -Chapter 5: Characterization of the P-i-N architecture with MoO3 from chapter 4 under space conditions, which was proven to be very stable and opened the possibility of using perovskite solar cells in high altitude conditions. The substitution of the doped transport layers led to devices with higher power conversion efficiencies (more than 20%, among the highest values for vacuum deposited CH3NH3PbI3 solar cells to date) and more robustness, passing stability tests under space conditions. The work developed in this thesis has opened an interesting field for vacuum deposited perovskite solar cells and changed the main fabrication routes in our laboratory

En este proyecto se ha creado un sistema software que permite la interacción con Twitter y sus diversas entidades, recopilando esta información para representar las distintas interacciones entre los usuarios de manera legible para el ser humano y así extraer conocimiento de las mismas.

Air pollution remains as a key unresolved problem in many urban areas. Cities with such problem are gradually implementing Traffic Management Strategies (TMS) to reduce the total kilometers travelled by vehicles and subsequently decrease emissions. However, a prior evaluation of such TMS is needed if the target goals want to be achieved. In this sense, the combination of traffic simulation with emissions and air quality models can be of great use to assess the potential impacts of such policies. This study presents an integrated modelling system tool for Barcelona that allows to estimate the changes induced by the implementation of TMS on traffic activity, emissions and air quality levels at a very spatial (street level) and temporal (hourly level) resolution.