A cidade e o rio: origem e evolução da frente ribeirinha de Lisboa

Em Lisboa, ao longo dos séculos, o homem foi conquistando as águas do Tejo. Hoje, após os diversos aterros, a frente ribeirinha da cidade é uma consolidada faixa de terreno, rematada por muros que, contra a «ondulação» do Tejo, definem uma expandida área que acolhe uma intensa actividade portuária. Foi nesta faixa junto do rio que se desenrolou parte importante da história de Lisboa, desde as ocupações romana e muçulmana, e também muito particularmente aquando do período dos Descobrimentos, da reconstrução pombalina pós-terramoto e do surto industrial do século XIX. Alguns destes momentos históricos encontram-se reflectidos nas inúmeras plantas, cartas e mapas disponíveis neste estudo, desde a Planta da Cidade de Lisboa : 1650, de João Nunes Tinoco, até ao Plano de Melhoramentos do Porto de Lisboa, de 1946. É com base nessas plantas, mas também em cartas manuscritas, relatos de época, gravuras e fotografias antigas – documentos em grande parte inéditos –, que este trabalho de investigação propõe cartografar este território, realizando desenhos originais que possibilitam um novo olhar sobre o seu processo de crescimento e consolidação. Assim, este estudo concilia todos estes elementos, constituindo uma análise completa que se debruça sobre a evolução da frente ribeirinha de Lisboa e que permite descobrir inúmeros aspectos até aqui desconhecidos, ajudando a responder à pergunta que hoje se coloca: perante o cenário que o porto actual atravessa, como melhor poderá Lisboa recuperar a relação com o rio?; THE CITY AND THE RIVER: ORIGIN AND EVOLUTION OF LISBON'S RIVERFRONT ABSTRACT: In Lisbon, over the centuries, man was conquering the waters of the Tagus. Today, after the various landfills, the city's riverfront is a consolidated strip of land, finished by walls that, against the "ripple" of the Tagus, define an expanded area that hosts an intense port activity. It was in this band along the river that unfolded important part of the history of Lisbon, from the Roman and Muslim occupations, and also very particularly during the period of the Discoveries, the post-earthquake reconstruction, and the industrial boom of the nineteenth century. Some of these historical moments are reflected in many plans, charts and maps available in this study, since the plan designated Planta da Cidade de Lisboa : 1650, made by João Nunes Tinoco, to the plan called Plano de Melhoramentos do Porto de Lisboa, drawn in the year of 1946. Based on these plans, but also in handwritten letters, time reports, antique prints and photographs – documents that are mostly unpublished – this research work proposes map this territory, performing original drawings that provide a new look at their growth process and consolidation. Thereby, this study combines all these elements, providing a complete analysis which focuses on the evolution of the Lisbon riverfront and that allows you to discover many aspects unknown until now, helping to answer the question that now arises: according to the present scenario that the harbour is going through, how can Lisbon recover the relationship with the river

Malware Analysis with Machine Learning

Tese de mestrado, Segurança Informática, Universidade de Lisboa, Faculdade de Ciências, 2022Malware attacks have been one of the most serious cyber risks in recent years. Almost every week, the number of vulnerability reports is increasing in the security communities. One of the key causes for the exponential growth is the fact that malware authors started introducing mutations to avoid detection. This means that malicious files from the same malware family, with the same malicious behaviour, are constantly modified or obfuscated using a variety of technics to make them appear to be different. Characteristics retrieved from raw binary files or disassembled code are used in existing machine learning-based malware categorization algorithms. The variety of such attributes has made it difficult to develop generic malware categorization methods that operate well in a variety of operating scenarios. To be effective in evaluating and categorizing such enormous volumes of data, it is necessary to divide them into groups and identify their respective families based on their behaviour. Malicious software is converted to a greyscale image representation, due to the possibility to capture subtle changes while keeping the global structure helps to detect variations. Motivated by the Machine Learning results achieved in the ImageNet challenge, this dissertation proposes an agnostic deep learning solution, for efficiently classifying malware into families based on a collection of discriminant patterns retrieved from its visualization as images. In this thesis, we present Malwizard, an adaptable Python solution suited for companies or end users, that allows them to automatically obtain a fast malware analysis. The solution was implemented as an Outlook add-in and an API service for the SOAR platforms, as emails are the first vector for this type of attack, with companies being the most attractive targets. The Microsoft Classification Challenge dataset was used in the evaluation of the noble approach. Therefore, its image representation was ciphered and generated the correspondent ciphered image to evaluate if the same patterns could be identified using traditional machine learning techniques. Thus, allowing the privacy concerns to be addressed, maintaining the data analysed by neural networks secure to unauthorized parties. Experimental comparison demonstrates the noble approach performed close to the best analysed model on a plain text dataset, completing the task in one-third of the time. Regarding the encrypted dataset, classical techniques need to be adapted in order to be efficient

Deep Adversarial Frameworks for Visually Explainable Periocular Recognition

Machine Learning (ML) models have pushed state­of­the­art performance closer to (and even beyond) human level. However, the core of such algorithms is usually latent and hardly understandable. Thus, the field of Explainability focuses on researching and adopting techniques that can explain the reasons that support a model’s predictions. Such explanations of the decision­making process would help to build trust between said model and the human(s) using it. An explainable system also allows for better debugging, during the training phase, and fixing, upon deployment. But why should a developer devote time and effort into refactoring or rethinking Artificial Intelligence (AI) systems, to make them more transparent? Don’t they work just fine? Despite the temptation to answer ”yes”, are we really considering the cases where these systems fail? Are we assuming that ”almost perfect” accuracy is good enough? What if, some of the cases where these systems get it right, were just a small margin away from a complete miss? Does that even matter? Considering the ever­growing presence of ML models in crucial areas like forensics, security and healthcare services, it clearly does. Motivating these concerns is the fact that powerful systems often operate as black­boxes, hiding the core reasoning underneath layers of abstraction [Gue]. In this scenario, there could be some seriously negative outcomes if opaque algorithms gamble on the presence of tumours in X­ray images or the way autonomous vehicles behave in traffic. It becomes clear, then, that incorporating explainability with AI is imperative. More recently, the politicians have addressed this urgency through the General Data Protection Regulation (GDPR) [Com18]. With this document, the European Union (EU) brings forward several important concepts, amongst which, the ”right to an explanation”. The definition and scope are still subject to debate [MF17], but these are definite strides to formally regulate the explainable depth of autonomous systems. Based on the preface above, this work describes a periocular recognition framework that not only performs biometric recognition but also provides clear representations of the features/regions that support a prediction. Being particularly designed to explain non­match (”impostors”) decisions, our solution uses adversarial generative techniques to synthesise a large set of ”genuine” image pairs, from where the most similar elements with respect to a query are retrieved. Then, assuming the alignment between the query/retrieved pairs, the element­wise differences between the query and a weighted average of the retrieved elements yields a visual explanation of the regions in the query pair that would have to be different to transform it into a ”genuine” pair. Our quantitative and qualitative experiments validate the proposed solution, yielding recognition rates that are similar to the state­of­the­art, while adding visually pleasing explanations

The yield curve as a predictor of recessions in the Euro Area: A multicountry analysis

This paper revisits the role of the yield spread to forecast recessions in the Euro Area. We show that the contribution of the spread can be decomposed into the effect of future expected changes in short term rates and the effect of the term premium. This decomposition is achieved with the use of a no arbitrage affine term structure model incorporating two latent factors that explain level and slope movements in the yield curve. We find that the expectations hypothesis component accounts for most of the predictability of the spread with part of this predictability reflecting the effects of the monetary policy stance. The results suggest, however, that the yield spread predictive content is driven by other factors independent of monetary policy

International Conference on Dynamic Control and Optimization - DCO 2021: book of abstracts

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IoTMapper: a metrics aggregation system architecture in support of smart city solutions

Smart cities are, nowadays, an unavoidable and growing reality, supported on software platforms that support city management, through the processing and presentation of a large number of data, obtained from sensors used throughout the cities. Low-power wide area networks (LPWAN) leverage the sensorization process; however, urban landscape, in turn, induces a high probability of change in the propagation conditions of the LPWAN network, thus requiring active monitoring solutions for assessing the city LPWAN network condition. Currently existing solutions usually consider the existence of only one type of LPWAN network to be monitored. In this paper, an architecture for aggregation of metrics from heterogeneous LPWAN networks is presented. The architecture, named IoTMapper, combines purpose build components with existing components from the FIWARE and Apache Kafka ecosystems. Implementation details for the LPWAN networks are abstracted by adapters so that new networks may be easily added. The validation was carried out using real data collected for long-range wide-area network (LoRaWAN) in Lisbon, and a simulated data set extrapolated from the collected data. The results indicate that the presented architecture is a viable solution for metrics aggregation that may be expanded to support multiple networks. However, some of the considered FIWARE components present performance bottlenecks that may hinder the scaling of the architecture while processing new message arrivals.info:eu-repo/semantics/publishedVersio

A Quaternionic Version Theory related to Spheroidal Functions

In dieser Arbeit wird eine neue Theorie der quaternionischen Funktionen vorgestellt, welche das Problem der Bestapproximation von Familien prolater und oblater sphäroidalen Funktionen im Hilberträumen behandelt. Die allgemeine Theorie beginnt mit der expliziten Konstruktion von orthogonalen Basen für Räume, definiert auf sphäroidalen Gebieten mit beliebiger Exzentrizität, deren Elemente harmonische, monogene und kontragene Funktionen sind und durch die Form der Gebiete parametrisiert werden. Eine detaillierte Studie dieser grundlegenden Elemente wird in dieser Arbeit durchgeführt. Der Begriff der kontragenen Funktion hängt vom Definitionsbereich ab und ist daher keine lokale Eigenschaft, während die Begriffe der harmonischen und monogenen Funktionen lokal sind. Es werden verschiedene Umwandlungsformeln vorgestellt, die Systeme harmonischer, monogener und kontragener Funktionen auf Sphäroiden unterschiedlicher Exzentrizität in Beziehung setzen. Darüber hinaus wird die Existenz gemeinsamer nichttrivialer kontragener Funktionen für Sphäroide jeglicher Exzentrizität gezeigt. Der zweite wichtige Beitrag dieser Arbeit betrifft eine quaternionische Raumfrequenztheorie für bandbegrenzte quaternionische Funktionen. Es wird eine neue Art von quaternionischen Signalen vorgeschlagen, deren Energiekonzentration im Raum und in den Frequenzbereichen unter der quaternionischen Fourier-Transformation maximal ist. Darüber hinaus werden diese Signale im Kontext der Spektralkonzentration als Eigenfunktionen eines kompakten und selbstadjungierteren quaternionischen Integraloperators untersucht und die grundlegenden Eigenschaften ihrer zugehörigen Eigenwerte werden detailliert beschrieben. Wenn die Konzentrationsgebiete beider Räume kugelförmig sind, kann der Winkelanteil dieser Signale explizit gefunden werden, was zur Lösung von mehreren eindimensionalen radialen Integralgleichungen führt. Wir nutzen die theoretischen Ergebnisse und harmonische Konjugierten um Klassen monogener Funktionen in verschiedenen Räumen zu konstruieren. Zur Charakterisierung der monogenen gewichteten Hardy- und Bergman-Räume in der Einheitskugel werden zwei konstruktive Algorithmen vorgeschlagen. Für eine reelle harmonische Funktion, die zu einem gewichteten Hardy- und Bergman-Raum gehört, werden die harmonischen Konjugiert in den gleichen Räumen gefunden. Die Beschränktheit der zugrundeliegenden harmonischen Konjugationsoperatoren wird in den angegebenen gewichteten Räumen bewiesen. Zusätzlich wird ein quaternionisches Gegenstück zum Satz von Bloch für monogene Funktionen bewiesen.This work presents a novel Quaternionic Function Theory associated with the best approximation problem in the setting of Hilbert spaces concerning families of prolate and oblate spheroidal functions. The general theory begins with the explicit construction of orthogonal bases for the spaces of harmonic, monogenic, and contragenic functions defined in spheroidal domains of arbitrary eccentricity, whose elements are parametrized by the shape of the corresponding spheroids. A detailed study regarding the elements that constitute these bases is carried out in this thesis. The notion of a contragenic function depends on the domain, and, therefore, it is not a local property in contrast to the concepts of harmonic and monogenic functions. Various conversion formulas that relate systems of harmonic, monogenic, and contragenic functions associated with spheroids of differing eccentricity are presented. Furthermore, the existence of standard nontrivial contragenic functions is shown for spheroids of any eccentricity. The second significant contribution presented in this work pertains to a quaternionic space-frequency theory for band-limited quaternionic functions. A new class of quaternionic signals is proposed, whose energy concentration in the space and the frequency domains are maximal under the quaternion Fourier transform. These signals are studied in the context of spatial-frequency concentration as eigenfunctions of a compact and self-adjoint quaternion integral operator. The fundamental properties of their associated eigenvalues are described in detail. When the concentration domains are spherical in both spaces, the angular part of these signals can be found explicitly, leading to a set of one-dimensional radial integral equations. The theoretical framework described in this work is applied to the construction of classes of monogenic functions in different spaces via harmonic conjugates. Two constructive algorithms are proposed to characterize the monogenic weighted Hardy and Bergman spaces in the Euclidean unit ball. For a real-valued harmonic function belonging to a Hardy and a weighted Bergman space, the harmonic conjugates in the same spaces are found. The boundedness of the underlying harmonic conjugation operators is proven in the given weighted spaces. Additionally, a quaternionic counterpart of Bloch’s Theorem is established for monogenic functions

A comparative analysis between local and exchange university students from Montevideo, Lisbon, and Padua

Funding Information: CC acknowledges the support given by the Calouste Gulbenkian Foundation through the Environmental Sustainability Grant from the Novos Talentos Científicos that supported the development of this work and the open access fee, and for organizing discussion sessions throughout the progress of the research. Publisher Copyright: Copyright © 2023 Castro and Gouveia.Energy Poverty (EP) is a growing concern in EU and national policies. Limited research has been conducted on students' perception of EP and vulnerability to EP, especially on how this may be modified if the student is a local or an exchange university student and how this interacts with the season (i.e., summer and winter). Therefore, the present research aims to deepen this understanding by analyzing and comparing students' perceptions of EP and exploring their vulnerability to EP, considering their background and the city they live in, using Montevideo in Uruguay, Lisbon in Portugal, and Padua in Italy, as case studies. To achieve these aims, two populations of university students in each city were surveyed: one of Local Students (LS) and another of Exchange Students (ES). Responses from 295 students to an online survey with 44 questions covering several aspects of EP and energy awareness, such as energy consumption habits, vulnerability drivers, energy equipment, and lived experience in maintaining comfortable internal temperatures, were collected in 2022. Differences between the perception of LS and ES in each city were analyzed, as well as differences in students' perceptions among cities. Although it is difficult to generalize, comfort levels seem to vary according to location, type of students, and season, but according to the results, there seems to be an interaction between these three factors. According to this research, most students did not identify themselves as living in EP, but several populations perceived discomfort in both winter and summer, showing their vulnerability to EP.publishersversionpublishe