Browsing by Issue Date, starting with "2025-01-01"
Now showing 1 - 5 of 5
Results Per Page
Sort Options
- Conflito Russo-UcranianoPublication . Hutnikevych, Alexandre ; Neves, CTN ST-HOS Bruno Alexandre Gonçalves; Gil, CMG M RES João Afonso Marques Coelho; Venislavskyy, VitaliyAtualmente, o conflito Russo-Ucraniano representa um dos maiores desafios à ordem internacional. Contudo, não pode ser compreendido apenas como um fenómeno isolado no presente: trata-se de uma disputa com raízes históricas profundas, associadas à ambição russa de obter acesso a mares de águas quentes, fruto dos seus condicionalismos geográficos. Desde o período imperial, a expansão para sul e a consolidação da presença no Mar Negro foram considerados objetivos estratégicos vitais, tanto para a defesa do território como para a projeção de poder e a afirmação da Rússia no sistema internacional. A península da Crimeia simboliza essa continuidade histórica e, pela sua posição geoestratégica, tornou-se o centro de gravidade do conflito, na sua componente naval. A sua anexação em 2014 não constituiu um episódio isolado, mas antes a reafirmação de uma lógica expansionista de longa duração, que o Kremlin procura legitimar através de uma narrativa histórica instrumentalizada, apresentando a agressão como uma “retomada” natural e não uma violação da soberania ucraniana e das normas internacionais. Neste enquadramento, a Ucrânia ficou privada da sua principal base naval e de grande parte da sua frota, passando a enfrentar um desequilíbrio estrutural face à superioridade da Frota do Mar Negro. Estas limitações levaram a Ucrânia a edificar uma estratégia naval defensiva, baseada no conceito de sea denial, através do desenvolvimento de meios assimétricos e inovadores que lhe permitem contestar a superioridade naval russa e garantir a defesa dos seus interesses no Mar Negro.
- Tábuas para o Cálculo da Hora a Bordo de Lopes BanhosPublication . Barreto, Sílvio D’Oliveira Sousa ; Canas, CMG RES António CostaNos séculos anteriores ao advento da navegação moderna, o posicionamento de uma embarcação em alto-mar dependia exclusivamente da observação dos astros. A evolução da navegação astronómica esteve, desde cedo, associada ao aperfeiçoamento dos métodos de cálculo da latitude e, sobretudo, da longitude, cujo tratamento matemático mais complexo levou ao surgimento de diversas tábuas destinadas a facilitar os cálculos a bordo. Esta dissertação centra-se no estudo e análise das Taboas para o Cálculo da Hora a Bordo, publicadas por J. E. Lopes Banhos em 1897. O trabalho é conduzido com o propósito de compreender a estrutura e a utilidade prática desta tábua, bem como a sua aplicação no cálculo da hora e da posição de um navio em alto-mar. O estudo inclui a contextualização histórica da navegação astronómica e uma explicação matemática das fórmulas utilizadas nas tábuas de Lopes Banhos. Com o objetivo de avaliar a eficácia e a clareza destas tábuas, procedeu-se a uma comparação com as tábuas de John William Norie. Para tal, resolveram-se casos práticos utilizando tanto o método do ângulo horário como o método de Marcq Saint Hilaire, aplicando-se as duas tábuas. Recorreu-se ainda a um ficheiro Excel para sistematizar os dados e avaliar a precisão dos resultados obtidos.
- Negotiation as a key enabler in NATO Multi-Domain Operations involving non-military entitiesPublication . Lopes, GMAR AN Xavier Santos; Lopes, GMAR AN Xavier SantosThis dissertation explores how NATO can enhance its negotiation capability when engaging with non-military actors within the context of Multi-Domain Operations. In an era marked by increasing operational complexity and cross-sector interdependence, NATO's effectiveness relies not only on its military capabilities but also on its ability to coordinate, align, and negotiate with civilian partners. The central issue addressed is how NATO can negotiate, reconciling military requirements with the capacities and constraints of non-military suppliers. To investigate this problem, the dissertation applies the NATO Defence College Strategic Foresight methodology. This involves the identification and prioritization of trends and uncertainties, the construction of scenarios based on key drivers, and the application of a backcasting process to derive strategic actions. The findings emphasize that negotiation must be recognized as a core institutional function, necessitating doctrinal clarity, sustained stakeholder engagement, modular negotiation capabilities, and interoperable information systems. The scenario analysis illustrates how NATO's negotiation relevance is shaped by its adaptability to divergent geopolitical and institutional conditions. The backcasting results point to a set of actions that remain valid across future trajectories, including the development of a NATO-wide negotiation doctrine, the integration of civil-military liaison structures, and the institutionalization of early coordination mechanisms.
- Computational Fluid Dynamics for Synthetic Data GenerationPublication . Pereira, Francisco Miguel Bastos; Barata, José; Moura, RicardoThis dissertation explores the use of computational fluid dynamics (CFD) for generating synthetic data in the context of biomimetic propulsion. It contributes directly to the SABUVIS II project, which involves a swarm of autonomous underwater vehicles designed for military and scientific applications. The study focuses on designing, simulating and evaluating bio-inspired fin propulsion systems with the aim of producing synthetic datasets for future Digital Twin integration. The objectives of this work are to develop a parametrized fin profile that can be easily and quickly modified in terms of both shape and movement, whether its amplitude, frequency of oscillation or the type of movement, in order to create a model for simulations and data generation. This model should be capable of running di!erent simulations to generate a diverse set of results. The methodology followed three stages. First, a bibliographic review mapped the state of research in biomimetic propulsion, synthetic data, and digital twins. Second, a CFD workflow modelled fin-driven propulsion, including fin profiling, mesh independence, domain setup, solver configuration, and UDFs for sinusoidal and turtle-inspired motions. Third, parametric simulations assessed flow velocity, thrust, hydrodynamic forces, energy use, and propulsion e"ciency under controlled conditions. Results show both movement types generate biologically consistent thrust and flow. Sinusoidal motion produced smoother velocity fields and steadier thrust, while turtle-inspired motion yielded localized peaks suited for rapid manoeuvring. E"ciency depended on fin length, frequency, and amplitude, with a 50 cm fin at 2 Hz giving the best thrust-to-energy ratio. The datasets also support synthetic data repositories and future digital twin development of the SABUVIS propulsion subsystem.
- Final Development and Construction of a Cost-Effective Unmanned Aerial Vehicle to Enhance Operational Capabilities of the Portuguese NavyPublication . Marques, João Rodrigo Teixeira; Policarpo, Hugo Filipe Diniz; Rego, Francisco Fernandes CastroVehicle (UAV) development for military use, including aerodynamics, structural stresses, materials, propulsion, and operational factors. The main objective was the construction of a functional UAV prototype for military applications. Given the growing relevance of UAVs in armed conflicts—particularly amid global tensions—this work addresses the urgent need for safe, effective, and low-cost aerial platforms. Drones allow remote operations, reducing risks to personnel while preserving battlefield effectiveness. However, many military UAVs are prohibitively expensive, while affordable options often lack endurance. This project aimed to develop a UAV, conceived by Portuguese Navy officers Eng. Joel Martins and Eng. José Rodrigues, with a budget under €5000. The project began with design changes to simplify manufacturing while considering the capabilities of the CEOV and SANFLOT units of the Portuguese Navy. Construction employed 3D printing for the internal structure and fuselage, while the planned carbon fiber skin was replaced with fiberglass due to budget and logistics, still ensuring structural performance. During manufacturing, several adaptations were required to overcome practical challenges. However, the process proved time-consuming, and delays in material delivery further extended the schedule. As a result, the project was concluded with the successful assembly of the UAV’s structure, while part of instrumentation integration, validation of calculations, and flight tests remain pending for future development. This work contributes to understanding UAV development in a military context and shows the importance of adaptability in low-cost aerospace engineering.