Semilinear fractional differential equations: global solutions, critical nonlinearities and comparison results

In this work we study several questions concerning to abstract fractional Cauchy problems of order α ∈ (0, 1). Concretely, we analyze the existence of local mild solutions for the problem, and its possible continuation to a maximal interval of existence. The case of critical nonlinearities and corresponding regular mild solutions is also studied. Finally, by establishing some general comparison results, we apply them to conclude the global well-posedness of a fractional partial differential equation coming from heat conduction theory.Conselho Nacional de Desenvolvimento Científico e TecnológicoCoordenação de aperfeiçoamento de pessoal de nivel superiorFundação de Amparo à Pesquisa do Estado de São PauloMinisterio de EducaciónMinisterio de Ciencia e InnovaciónJunta de Andalucí

Depositional setting and stratigraphic patterns of Pre-Salt carbonates in a sector of the Santos Basin, Brazil

Tese de mestrado, Geologia (Estratigafia, Sedimentologia e Paleontologia) Universidade de Lisboa, Faculdade de Ciências, 2019This work aims to better understand the Pre-Salt Barra-Velha Formation lacustrine carbonates and their depositional setting and diagenetic evolution in a specific zone of Santos Basin, Brazil. A multi-scale workflow based on well core analysis and its relation with well log data and stratigraphic seismic interpretation was used to provide a better understanding of facies distribution and depositional cycles, with focus on the Upper Sag unit. The outcomes from the different tasks allowed to develop a conceptual depositional model with application on reservoir characterization, representing a generic regional propose applicable to the Pre-Salt carbonates in the studied area. The results from the six described wells demonstrate high depositional cyclicity, indicating mainly a shallow water environment, being possible to define a generic facies sequence based on base-level position and energy variations. Facies successions identification allowed the recognition of sequence boundaries, which demonstrated that changes in base-level and accommodation space were responsible for different facies deposition. The integration of multiscale data with seismic interpretation demonstrate a progressive basin fill, starting north and gradually reaching structural higher positions. Paleogeomorphology strongly controlled sediment deposition, as different depositional environment conditions were observed in different structural positions, with high base-level position and low energy facies being mainly recognized in structural lows and low base-level position and high energy facies being mostly identified in structural highs. It was also recognized an affinity of diagenetic processes with paleogeomorphology, with fluid circulation having a major impact in structural low positions resulting in porosity reduction processes, while in structural high positions, porosity generation or enhancing processes tend to be more frequent. The understanding of depositional environments retrieved from this study will enhance the geological understanding of Santos Basin depositional setting and may assist on hydrocarbon exploration by providing a more robust reservoir characterization, from a geological point of view

Técnicas de previsão: aplicação a redes celulares

Due to the growing competitiveness and aggressiveness of the market, the network operators’ strategy is increasingly based on improving infrastructures and optimizing existing resources, in a way that provides the best experience to the user. To do this, the operator analyzes the Key Performance Indicators (KPIs) and uses forecasting methods to predict and plan the modifications needed in the network. With this as basis, this work focuses on the study and analysis of different forecasting methods and their implementation in Python, so that the operator can obtain automate real-time predictions of the future behavior of his network.Devido ao aumento da competitividade e agressividade do mercado, cada vez mais a estratégia dos operadores de redes móveis passa pelo melhoramento das infraestruturas e otimização dos recursos já existentes, de modo a proporcionar a melhor experiência aos seus utilizadores. Para isto, recorrem à análise de indicadores chave de desempenho (KPIs) e ao uso de métodos de previsão para prever e planear alterações a realizar na sua rede. Tendo isto como base, esta dissertação foca-se no estudo e análise de diferentes métodos de previsão e sua implementação em Python, de maneira a obter previsões do futuro comportamento da rede em tempo real e de forma automatizada.Mestrado em Engenharia Eletrónica e Telecomunicaçõe

Including context in a routing algorithm for the internet of things

Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para obtenção do grau de Mestre em Engenharia InformáticaThe “Internet of Things” assumes that a large number of devices which are used on a daily basis will eventually become connected to the Internet. This scenario will provide room for a large set of new applications, however the network connections of an enormous set of nodes, which can be connected and disconnected, can move around and which have limitations with regards to their processing and communication capabilities, raises the need for the development of new message routing algorithms, different from those being in use today. In this thesis, a contribution is made towards the development of this type of algorithms. In particular, the idea which is tested is whether routing algorithms can improve their performance at various levels, such as, message delivery time, number of messages lost, power consumption, etc., if in the routing decisions these algorithms can make use of the concept of “Context”. Within the framework of this thesis, the “Context” is the organized collection of information which the routing algorithm collects from the environment surrounding the network nodes, and which allows it to make better routing decisions. This information can be related to low-level issues, such as, node location, power required to send a message, etc., as well as, with constraints related to the application, such as, message priority, maximum delivery time, etc. In order to evaluate this approach, this thesis proposes a routing algorithm called C-AODV. As the name suggests, it is based on the ADOV algorithm, however it is modified in several aspects; in particular, the possibility of using information collected from the context can be utilized to improve message routing. In order to test the proposed solution, several tests were performed on the NS-3 simulator which allowed the evaluation of the algorithm functionalities. The tests performed indicate that the proposed solution is valid

Automated and intelligent hacking detection system

Dissertação de mestrado integrado em Informatics EngineeringThe Controller Area Network (CAN) is the backbone of automotive networking, connecting many Electronic ControlUnits (ECUs) that control virtually every vehicle function from fuel injection to parking sensors. It possesses,however, no security functionality such as message encryption or authentication by default. Attackers can easily inject or modify packets in the network, causing vehicle malfunction and endangering the driver and passengers. There is an increasing number of ECUs in modern vehicles, primarily driven by the consumer’s expectation of more features and comfort in their vehicles as well as ever-stricter government regulations on efficiency and emissions. Combined with vehicle connectivity to the exterior via Bluetooth, Wi-Fi, or cellular, this raises the risk of attacks. Traditional networks, such as Internet Protocol (IP), typically have an Intrusion Detection System (IDS) analysing traffic and signalling when an attack occurs. The system here proposed is an adaptation of the traditional IDS into the CAN bus using a One Class Support Vector Machine (OCSVM) trained with live, attack-free traffic. The system is capable of reliably detecting a variety of attacks, both known and unknown, without needing to understand payload syntax, which is largely proprietary and vehicle/model dependent. This allows it to be installed in any vehicle in a plug-and-play fashion while maintaining a large degree of accuracy with very few false positives.A Controller Area Network (CAN) é a principal tecnologia de comunicação interna automóvel, ligando muitas Electronic Control Units (ECUs) que controlam virtualmente todas as funções do veículo desde injeção de combustível até aos sensores de estacionamento. No entanto, não possui por defeito funcionalidades de segurança como cifragem ou autenticação. É possível aos atacantes facilmente injetarem ou modificarem pacotes na rede causando estragos e colocando em perigo tanto o condutor como os passageiros. Existe um número cada vez maior de ECUs nos veículos modernos, impulsionado principalmente pelas expectativas do consumidores quanto ao aumento do conforto nos seus veículos, e pelos cada vez mais exigentes regulamentos de eficiência e emissões. Isto, associada à conexão ao exterior através de tecnologias como o Bluetooth, Wi-Fi, ou redes móveis, aumenta o risco de ataques. Redes tradicionais, como a rede Internet Protocol (IP), tipicamente possuem um Intrusion Detection Systems (IDSs) que analiza o tráfego e assinala a presença de um ataque. O sistema aqui proposto é uma adaptação do IDS tradicional à rede CAN utilizando uma One Class Support Vector Machine (OCSVM) treinada com tráfego real e livre de ataques. O sistema é capaz de detetar com fiabilidade uma variedade de ataques, tanto conhecidos como desconhecidos, sem a necessidade de entender a sintaxe do campo de dados das mensagens, que é maioritariamente proprietária. Isto permite ao sistema ser instalado em qualquer veículo num modo plug-and-play enquanto mantém um elevado nível de desempenho com muito poucos falsos positivos

Exchange market pressure and capital controls, the case of Brazil

When defining monetary policy, emerging countries tend to protect their independent monetary policy, by intervening in foreign exchange markets to stabilise the exchange rate and by using capital controls to insulate their domestic economy from international investment fluctuations. In this scenario, currency volatility is dampened by official interventions and so an index that reveals the actual pressure affecting a currency is necessary. This work proposes an Exchange Market Pressure measure for the Brazilian economy, incorporating an endogenous proxy for capital control policies. We find out that there is evidence of pressure being relieved by the Brazilian central authorities and that the inclusion of a capital control proxy in the measure inflates the power of reserves in relieving currency pressure