“With what can we compare the kingdom of God?” Latin American Liberation Theology and the Challenge of Political Projects

Who baked the pie in the sky? Who sowed and harvested its fruits, gathered the ingredients and put it into the oven? And also: who paved heaven’s streets of gold, crafted the trumpets of the cherubim, and erected God’s throne? Albeit the ethereal tune that marks speculative questions of this nature, there is a profoundly concrete dimension implied in images such as these I just described. Heaven, paradise, kingdom of God: these are theological categories for a reality that demand a ground on which to stand: someone has to bake the pie – even in the sky. Heavenly hopes are intrinsically connected to historical paths in a symbiosis that knows no division

Assessing the emotional impact of video using machine learning techniques

Typically, when a human being watches a video, different sensations and mind states can be stimulated. Among these, the sensation of fear can be triggered by watching segments of movies containing themes such as violence, horror and suspense. Both the audio and visual stimuli may contribute to induce fear onto the viewer. This dissertation studies the use of machine learning for forecasting the emotional effects triggered by video, more precisely, the automatic identification of fear inducing video segments. Using the LIRIS-ACCEDE dataset, several experiments have been performed in order to identify feature sets that are most relevant to the problem and to assess the performance of different machine learning classifiers. Both classical and deep learning techniques have been implemented and evaluated, using the Scikit-learn and TensorFlow machine learning libraries. Two different approaches for training and testing have been followed: film-level dataset splitting, where different films were used for training and testing; and sample-level dataset splitting, which allowed that different samples coming from the same films were used for training and testing. The prediction of movie segments that trigger fear sensations achieved a F1-score of 18.5% in the first approach, a value suggesting that the dataset does not adequately represent the universe of movies. The second approach achieved a F1-score of about 84.0%, a substantially higher value that shows promising outcomes when performing the proposed task.Quando o ser humano assiste a filmes, diferentes sensações e estados de espírito são despoletados. Entre estes encontra-se o medo, que pode ser despoletado através da visualização de excertos de filmes contendo, por exemplo, violência gráfica, horror ou suspense. Tanto a componente visual como a auditiva contribuem para o despoletar desta sensação. Nesta dissertação é analisada a utilização de aprendizagem automática para prever o impacto emocional que a visualização de vídeos possa causar nas pessoas, mais concretamente os segmentos de um filme que despoletam a sensação de medo. Foram realizadas diversas experiências usando o conjunto de dados LIRIS-ACCEDE com os objetivos de encontrar conjuntos de atributos de imagem e áudio com maior relevância para o problema e de avaliar o desempenho de diversos modelos de aprendizagem automática usados para classificação. Foram usados diversos algoritmos clássicos e de aprendizagem profunda, recorrendo-se às bibliotecas Scikit-learn e TensorFlow. No que se refere à separação dos dados usados para treino e teste foram seguidas duas abordagens: divisão dos dados ao nível do filme, sendo usados filmes distintos para treino e teste; e divisão dos dados ao nível da amostra, possibilitando que os conjuntos de treino e teste contenham amostras distintas, mas pertencentes aos mesmos filmes. Para previsão dos segmentos que despoletam medo, na primeira abordagem chegou-se a um resultado de F1-score de 18,5%, concluindo-se que o conjunto de dados usado não é representativo, e na segunda abordagem a um F1-score de 84,0%, um valor substancialmente mais alto e promissor no desempenho da tarefa proposta

Monetary policy, financial frictions and business cycles

Tese de doutoramento em EconomiaNas últimas décadas, a sofisticação e complexidade dos mercados financeiros tem exposto cada vez mais a fragilidade da economia real a atritos financeiros, o que levanta questões importantes sobre o papel do crédito nos ciclos económico. A textit Grande Recessão é um lembrete gritante de que atritos financeiros podem desempenhar um papel fundamental nas flutuações do ciclo económico, com o acúmulo de desequilíbrios durante tempos tranquilos a conduzir a uma destruição grande e persistente de riqueza quando a bolha estoura, que pode então espalhar-se para a economia real. O objetivo desta tese é explorar a interação entre fricções financeiras e os ciclos económicos, em primeiro lugar abordando a relação entre as restrições aos empréstimos e seu impacto sobre as variáveis macroeconômicas e, em segundo lugar, analisando como as flutuações no risco afetam os ciclos económicos. Para este fim, baseamo-nos em dois modelos encontrados na literatura, que possuem os ingredientes-chave que levaram os autores a argumentar que atritos financeiros podem, em grande escala, ser responsáveis por flutuações nas variáveis macroeconômicas. No Capítulo 1, abordamos o modelo de Jermann and Quadrini (2012), que introduz choques di retamente no sistema financeiro que se propagam para a economia real; foi realizada uma análise das propriedades do modelo nos domínios temporal e da frequência. O uso de ôndulas permitiu uma avaliação de como o modelo se ajusta aos dados em diferentes frequências e em momentos específicos no tempo. Uma característica específica desse modelo é que ele introduz choques dire tamente no sistema financeiro, que se propagam para a economia real. É também um dos primeiros a abordar este canal dentro de uma estrutura de Equilíbrio Geral Estocástico Dinâmico (DSGE). Poucas pesquisas foram realizadas sobre o papel desempenhado pelos mercados financeiros e de crédito durante as recessões dos anos 1970 e início dos anos 1980. No Capítulo 2, seguindo algumas evidências sobre o endurecimento dos padrões de crédito antes ou durante os períodos de recessão, bem como as conclusões de Bernanke et al. (1999) de que fricções financeiras po dem afetar o tamanho das flutuações do ciclo de negócios, estendemos o modelo de Jermann and Quadrini (2012) para introduzir choques no preço do petróleo. O objetivo era analisar a contribuição das fricções financeiras durante este período, onde as recessões foram atribuídas principalmente a grandes aumentos nos preços do petróleo. Os atritos financeiros podem amplificar os ciclos económicos, levando a flutuações macroeconômi cas mais pronunciadas, seja por choques iniciados na economia real ou no próprio sistema financeiro. O papel da política monetária também pode depender da fonte do choque e do canal de transmissão. No Capítulo 3, estabelecemos uma comparação entre as séries temporais empíricas dos prin cipais agregados macroeconômicos durante o primeiro trimestre de 1985 até o último trimestre de 2019, e as séries simuladas a partir das contribuições dos choques incluídos em dois modelos DSGE distintos. O primeiro modelo é a versão neo-keynesianos do modelo de Jermann and Quadrini (2012), que estende Smets e Wouters (2007) com uma restrição de execução que pode ser interpretada como o grau de disposição dos bancos em conceder empréstimos, como uma proxy de padrões de crédito. O segundo modelo é o de Christiano et al. (2014b), que é baseado no mecanismo de acelerador financeiro do modelo de Bernanke et al. (1999), introduzindo choques de risco. Final mente, comparou-se as duas abordagens distintas de modelagem de atritos financeiros, recorrendo às diferentes fontes e origens de choques. Para a comparação, foram empregues as ferramentas decorrentes das ôndulas para analisar o quanto os atritos financeiros podem explicar das flutuações observadas em diferentes frequências.Over the last decades, the sophistication and complexity of financial markets has increasingly exposed the fragility of the real economy to financial frictions, which raises important issues regarding the role of credit in business cycles. The Great Recession is a stark reminder that financial frictions can play a key role in business cycle fluctuations, with the buildup of imbalances during tranquil times leading to the large and persistent destruction of wealth when the bubble bursts, which may then spill over to the real economy. The purpose of this thesis is to explore the interaction between financial frictions and business cy cles, firstly by addressing the relationship between borrowing constraints and their impact on macroe conomic variables and, secondly, by analyzing how fluctuations in risk affect business cycles. To this end, we relied on two models found in literature, which possess the key ingredients that have led the authors to argue that financial frictions may, on a large scale, be responsible for fluctuations in macroeconomic variables. In Chapter 1, one began with the Jermann and Quadrini (2012) model, which introduces shocks directly in the financial system that propagate to the real economy; an analysis was undertaken of the model properties in the time-frequency domains. The use of wavelet tools allowed for an evaluation of how the model fits the data at different frequencies, and at specific moments in time. A specific feature of this model is that it introduces shocks directly in the financial system, which then spill over to the real economy. It is also one of the first to address this channel within a Dynamic Stochastic General Equilibrium (DSGE) framework. Little research has been conducted on the role played by financial and credit markets during the 1970s and early 1980s recessions. In Chapter 2, following some evidence on the tightening of credit standards before or during the recession periods, as well as the findings by Bernanke et al. (1999) that financial frictions can affect the size of business cycle fluctuations, we extended the Jermann and Quadrini (2012) model to introduce oil price shocks. The aim was to analyze the contribution of financial frictions during this period, where the recessions were mainly attributed to large increases in oil prices. Financial frictions can amplify business cycles, leading to more pronounced macroeconomic fluc tuations, either due to shocks starting in the real economy or in the financial system itself. The role of monetary policy may also be dependent on the source of the shock and the transmission channel. In Chapter 3 we established a comparison between the empirical time series of major macroeco nomic aggregates during the first quarter of 1985 to the last quarter of 2019, with simulated series computed from the contributions of the shocks included in two distinct DSGE models. The first model is the Jermann and Quadrini (2012) New Keynesian version of the model, which extends the Smets and Wouters (2007) with an enforcement constraint that may be interpreted as the degree of willing ness of banks to lend, as a proxy of credit standards. The second model is the Christiano et al. (2014b) model, which is based on the Bernanke et al. (1999) financial accelerator mechanism, thus introduc ing risk shocks. Finally, one compared two distinct approaches of modelling financial frictions, using different sources and origins of shocks. For the comparison, wavelet tools were employed to analyze how deeply financial frictions can explain the observed fluctuations at different frequencies.This work has been supported by the Doctoral scholarship SFRH/BD/96380/2013 funded by FCT, the Portuguese Ministry of Science, Technology and Higher Education, through national funds, and co-financed by the European Social Fund (ESF) through the Operational Programme for Human Capital (POCH)

Gestão de conteúdos digitais em múltiplos monitores

With the generalized use of systems for digital contents dissemination arises the opportunity for implementing solutions capable of evaluating audience reaction. This dissertation reflects the implementation of one of those solutions. To this end, the development involved adapting a previously functional digital signage system. In this sense, digital cameras were paired to the content display terminals in order to capture information from the area in front of them. Using computer vision technologies, the terminals detect, in real time, people who appear in the cameras’ field of view, and this information is communicated to a server for data extraction. On the server, methods are used to perform face and emotion recognition, and also to extract data indicating the position of the head, which allows the calculation of an attention coefficient. The data is stored in a relational database, and can be consulted through a web platform, where they are presented associated with the contents corresponding to the moment of their capture and extraction. This solution thus allows the evaluation of the impact of the digital contents presented by the system.Com a utilização generalizada de sistemas de disseminação de conteúdos digitais, surge a oportunidade de implementar soluções capazes de avaliar a reacção do público. Esta dissertação reflete a implementação de uma dessas soluções. Para isso, o desenvolvimento passou pela adaptação de um sistema de sinalização digital previamente funcional. Neste sentido, aos terminais de exposição de conteúdos, foram emparelhadas câmaras digitais de modo a permitir a captação de informação da área à frente destes. Com recurso a tecnologias de visão de computador, os terminais fazem, em tempo real, deteção de pessoas que apareçam no campo de visão das câmaras, sendo esta informação comunicada a um servidor para extração de dados. No servidor, são utilizados métodos para realização de reconhecimento de faces e emoções, e também é feita extração de dados indicadores da posição da cabeça, o que permite o cálculo de um coeficiente de atenção. Os dados são guardados numa base de dados relacional e podem ser consultados através de uma plataforma web, onde são apresentados associados aos contéudos correspondentes ao momento de captação e extração destes. Esta solução, permite, assim, a avaliação do impacto dos conteúdos digitais apresentados pelo sistema.Mestrado em Engenharia de Computadores e Telemátic

Eco-efficiency assessment in apple production and storage in the northeast of Portugal

Cost reduction, product quality, and customer demands have been pressing the agro-industrial sector to adopt more sustainable practices. Assessing the environmental performance of the food sector worldwide is crucial to reduce the environmental impact of agricultural and industrial practices. This study focus on the assessment of the eco-efficiency of the apple production and storage in the northeastern region of Portugal, one of the largest production regions, using a set of environmental indicators such as energy intensity (EI), water withdrawn intensity (WWI) and GHG emission intensity (GEI). System boundaries include the farming and the storage subsystems. Upstream and down-stream processes such as fertilization production, apple distribution and waste treatment were not taken into account. Inventory information was gathered from two apple farms and one apple storage company. Data was gathered for a reference year. Results show that each ton of apple exiting the system requires on average 32.7 kgoe of primary energy, 74.9 m3 of water and generates an emission of 75.2 kgCO2e. Apple orchard irrigation was identified as the most energy-demanding activity with up to 63% of the energy input. Industrial cold was identified as the most energy-demanding activity (50%) in the apple storage stage. Water is required in both subsystems but the amount used in the storage is residual (<1%) when compared with its use by agricultural subsystem. Taking into account the GHG emissions from the use of energy, apple cultivation had a lower contribution for GEI (40%) than the apple storage (60%). Unlike other food systems, a more eco-efficient apple production can be accomplished through improvements in both stages, since energy costs and environmental impacts are greatly associated with energy use.info:eu-repo/semantics/publishedVersio

Comportamento ao fogo de elementos estruturais em aço de inércia variável

The present thesis describes a numerical parametric study on the stability of web-tapered I-section members in fire, with the ultimate goal of proposing safe, practical and accurate simplified methodologies for the safety check of these members at elevated temperatures. Currently, the verification of structural elements with complex support conditions and/or of non-prismatic members at normal temperature is done with the General Method (clause 6.3.4 of Part 1-1 of Eurocode 3). However, the fire part of the norm (EN 1993-1- 2) provides no further indication regarding its applicability at elevated temperatures, apart from adapting the methodology to fire using the reduction factors for steel material properties. In addition, EN 1993-1-2 provides a single buckling curve regardless of member type, loading or geometry, which has shown to be a significant limitation of the norm. The numerical framework developed in this work to obtain the ultimate resistance of tapered members was carried out using the finite element program SAFIR to perform Geometrically and Materially Non-linear Analyses with Imperfections (GMNIA) with shell finite elements. The numerical models were validated against numerical and experimental data from the literature, both at normal and at elevated temperatures. First, it was shown that the adaptation of normal temperature methodologies to fire is not enough to account for all the nuances of the structural behaviour of steel at elevated temperatures and to produce accurate predictions of resistance for tapered columns, beams and beam columns. Regarding the General Method, this method has returned unsafe stability predictions for tapered columns and overly conservative forecasts for beams and beam-columns. Then, supported by approximately 50000 GMNIAnalyses, proposals for the calibration of the General Method for the verification of these members were developed in the scope of this work, leading to safe and more accurate predictions by the methodology in fire, in line with the design philosophy of Eurocode 3.A presente tese descreve um estudo numérico paramétrico no âmbito da estabilidade de elementos de inércia variável com secção “I” em situação de incêndio, com o objetivo de propor metodologias simplificadas seguras, práticas e precisas para a verificação de segurança destes elementos a elevadas temperaturas. A verificação de elementos estruturais com condições fronteira complexas e/ou nãouniformes é levada a cabo com o Método Geral (clausula 6.3.4 da Parte 1-1 do Eurocódigo 3). No entanto, a parte da norma dedicada ao fogo (EN 1993-1-2) não fornece indicações especificas relativamente à sua aplicabilidade a elevadas temperaturas, à exceção da adaptação da metodologia ao fogo utilizando os fatores de redução das propriedades do aço. Adicionalmente, a EN 1993-1-2 prevê uma única curva de encurvadura, não obstante do tipo de elemento, carregamento ou geometria, o que demonstrou ser uma limitação significativa da norma. O estudo numérico desenvolvido neste trabalho com vista à obtenção da resistência última dos elementos de inércia variável foi levado a cabo com o programa de elementos finitos SAFIR e análises não lineares com imperfeições (GMNIA) com elementos finitos de casca. Os modelos numéricos foram validados por resultados numéricos e experimentais da literatura tanto à temperatura normal como a temperaturas elevadas. Em primeiro lugar, demonstrou-se que a adaptação ao fogo de metodologias de temperatura normal não é suficiente para ter em conta todas as nuances do comportamento estrutural do aço a temperaturas elevadas e para produzir previsões precisas da resistência de colunas, vigas e vigas-coluna de inércia variável. No que diz respeito ao Método Geral, este demonstrou ser inseguro para colunas e demasiado conservativo para vigas e vigas-coluna de inércia variável. Posteriormente, suportadas por cerca de 50000 análises GMNIA, foram desenvolvidas, no âmbito deste trabalho, propostas para a calibração do Método Geral para a verificação destes elementos, permitindo a obtenção de previsões de estabilidade seguras e mais precisas com a referida metodologia em situação de incêndio, de acordo com a filosofia de dimensionamento do Eurocódigo 3.Programa Doutoral em Engenharia Civi

Urban vegetation as a filter for airborne particles: brief studies

Urban vegetation has been widely recognized for its capability to improve air quality. Vegetation absorbs air pollutants through leaf stomata and intercepts airborne particles on their foliar surfaces. To investigate the overall interaction between vegetation and airborne particles, PM10 measurements were carried out in a small Portuguese city (Bragança), under two distinct experimental designs. In the first one, PM10 concentrations were sequentially monitored in six different points, placed on two linear paths intersecting areas with contrasting plant cover and crossed by a low traffic urban road. Real time measurements were conducted throughout the growing season encompassing a total of twelve trials. In the second experimental configuration, diesel exhaust particles were released into the ambient air using an internal combustion engine while real-time measurements of PM10 were taken in different locations in front and behind a 2-meter-high by 1.5-meter-wide Pyracantha hedge. Results from both experiments showed the ability of vegetation in filtering air particles. Although no significant linear relationship was found between PM10 and foliar density, PM10 levels were predominantly lower in the path with higher foliar coverage. A good filtering performance was also found for the Pyracantha hedge when exposed to diesel exhaust particles, especially when the pollution source was positioned closer to the green barrier. Particle reductions up to 95% were measured, indicating that placing dense vegetation near pollution sources (e.g. roads) will certainly be an excellent choice for improving air quality in any urban system

FV-RAD : a practical framework for rapid application development

Estágio realizado na OPT-Optimização e Planeamento de Transportes, S.ATese de mestrado integrado. Engenharia Informática e Computação. Faculdade de Engenharia. Universidade do Porto. 200

An SDN-based Overlay Networking Solution for Transparent Multi-homed Vehicular Communications

This dissertation consists in the design and development of an Overlay Network for vehicular applications using the SDN paradigm, capable of supporting seamless handover and load balancing between multiple Vehicle-to-Infrastructure (V2I) networks, and also seamless handover of users' terminals between different vehicle zones, such as train carriages. The main contributions of this work are threefold: 1) the overlay SDN-based network architecture designed for vehicular applications such as trains, contemplating the support for multiple V2I operators and multiple gateways per vehicle (e.g., one per carriage); 2) the SDN orchestration component that implements the handover (performed by a User Terminal) from one carriage to another, without Internet connection interruption; and 3) the SDN orchestration component that implements the load-balancing of traffic over multiple V2I links that connect each carriage to the Internet, optimizing the utilization of available network resources and resulting QoS. All the features related to these contributions were implemented in a centralized SDN controller, which has a holistic view of the overlay network, which orchestrates the network hardware on-board of the vehicles. A Proof-of-Concept of the overlay network and the developed components was implemented using Virtual Machines emulating: the network elements of two carriages; the user terminals; a centralized orchestrator; an Internet gateway; and multiple V2I connections representing different operators. Different functional and performance tests were executed, targeting each component, which allowed to successfully validate each contribution