RCIPL
Repositório Institucional do Politécnico de Lisboa
Entradas recentes
Alternativas à utilização de travessas de madeira creosotadas na via-férrea
Publication . Silva, Inês Amaral Ribeiro Pereira da; Rodrigues, Fernanda de Jesus Viana Lopes; Martins, Armando do Carmo
As travessas de madeira tratadas com creosoto, devido ao seu baixo custo, facilidade de instalação e desempenho satisfatório em serviço, foram, durante várias décadas, um dos elementos estruturais mais utilizados na via-férrea. Contudo, fruto de estudos realizados, constatou-se que o creosoto é uma substância com efeitos comprovadamente nocivos para a saúde humana e para o ambiente, pelo que a sua utilização tem vindo a ser fortemente restringida nomeadamente pela Comunidade Europeia que aprovou legislação nesse sentido. Esta nova realidade, coloca ao setor ferroviário a necessidade de encontrar alternativas que assegurem o mesmo nível de desempenho estrutural, mas que sejam seguros ao nível da saúde, mas igualmente sustentáveis em termos ambientais. Neste enquadramento, a presente dissertação centra-se no estudo das alternativas às travessas de madeira creosotadas, com ênfase nas soluções sintéticas, assumidas como produtos inovadores e ainda de carácter pioneiro no panorama ferroviário nacional. Com esse objetivo, procede-se a uma caracterização das diferentes tipologias de via-férrea (balastradas e não balastradas), analisando as suas condições de utilização, vantagens, desvantagens e limitações, sendo igualmente sistematizadas as principais opções atualmente disponíveis para substituição das travessas de madeira. No documento é igualmente feita uma caracterização e análise de processos de fabrico, propriedades mecânicas e aspetos normativos associados às novas soluções de travessas, procurando avaliar a sua aplicabilidade em diferentes contextos ferroviários e reforçar o seu potencial enquanto solução tecnológica emergente. Finalmente, no âmbito do caso de estudo é dada especial atenção à substituição das travessas de madeira atualmente instaladas na ponte de Alferrarede na Linha da Beira Baixa, envolvendo não só os aspetos inerentes à montagem, mas também o posterior desempenho em serviço, incluindo a definição de indicadores para um futuro plano de monitorização. Na fase inicial de produção do presente documento foi prevista a substituição de travessas na ponte da Várzea, igualmente na Linha da Beira Baixa, não tendo a mesma sido acompanhada, fruto da reprogramação da ação pela IP para 2026.
RFID solutions evaluation in industrial container access control
Publication . Silva, Tiago Duque Leite Vieira da; Serrador, António João Nunes
Abstract
Identifying and recording the flow of industrial waste containers through access points can pose significant challenges in industrial environments. Manual registration methods can lead to registration failures that pose risks for a company, particularly for the security of assets and operational efficiency. Thus, the identification of container crossings through the facility’s gateways is essential for reinforcing security measures and optimising operational management in industrial environments. This work investigates the application of passive RFID (Radio Frequency IDentification) technology to address these challenges. A pilot architecture was developed, the most suitable hardware was selected and tested, and the system was installed in a waste management company, supported by a background service for processing and recording tag event data. The system was tested in real conditions with various crossing scenarios. RFID tags were installed on the company’s containers, and their passages through the gateway were monitored. Detection quality and middleware performance were evaluated through transaction statistics. The results show that the passive rigid tags used in the project significantly improve their
performance when they have a metal background, increasing their detection capacity from 64% to 100%. It was also concluded that a company can benefit significantly in financial terms as a result of improved operational management and the deterrent effect on theft.
Monitoring quality of air in urban environments using LoRa technology
Publication . Balona, Bernardo da Silva; Pires, Luís Miguel Rego
Abstract
This dissertation main objective to monitor quality of air in urban environments which are densely populated using quality of air sensors, to ensure real-time monitoring, LoRa/LoRaWAN communication will be used and therefore studied in order to understand the communication in metropolitan areas. This dissertation aims to fully experiment with the communications of values read by sensors and a LoRa cloud, all while using LoRa and a gateway. This type of project can extrapolate and evaluate the use of LoRaWAN in smart cities. By using LoRa/LoRaWAN, the objective consists of finding a low-cost option that provides real-time monitoring to measure and acquire sensor data. Moreover, this integration will allow to evaluate the viability of LoRa/LoRaWAN networks for environmental monitoring in smart cities and as a viable option for institutions to use this solution to easily monitor air quality in dense urban cities and vast countryside. This report presents a state of art of the components the system will use such as sensors, a MCU that will employ LoRa communication and a Gateway to pass the acquired sensor data to a server cloud which will then show the values through an API, which showed expected values of concentration, percentage and other units, such as micrometers, in the atmosphere. With the dioxide carbon sensor, we could go even further in the experimentation and understood the value expected of concentration would be around 350 ppm, with the practical values being 351 ppm. Results about values read will then be presented to understand the quality of air in the studied area and to compare these results with official values and make comparisons, measuring, the sensors’ efficiency. Radio test results will also be discussed to better understand the communication length that LoRa can achieve in cities with the higher values around 1,7 km with a Spreading Factor of 7 and with a Transmitting Power of 10, 12 and 14 dBm. In addition to this entire system, it was also created a predictive system to conclude about the general quality of air with the values obtained.
Design of a programmable photonic integrated circuit based on carrier depletion phase shifters
Publication . Velázquez, Ernesto Lazaro Chavez; Lourenço, Paulo Jorge Passos Sério; Fantoni, Alessandro
Abstract
Photonic integrated circuits (PICs) have appeared in response to current technological challenges such as increased speed, demand for greater bandwidth and processing capacity, especially for applications that require extremely fast, high-performance data processing that Integrated Circuits (ICs) cannot satisfy. The range of applications for this technology includes ultra-fast data centers, optical communications, biosensors, sensors for vehicles, quantum processors, and Artificial Intelligence (AI). As this technology continues to advance, there is a growing academic and scientific need to contribute to technology, which in turn opens new market opportunities. In this work, we will analyze the main optoelectronic properties of the materials used for PIC design and the latest advances in waveguide and coupler topologies, focusing on hydrogenated amorphous silicon (a-Si:H) as the main material and directional couplers as the main structure. An architecture will be proposed that looks to respond to problems in conventional directional couplers. It is also intended to use this new coupler design to create a programmable circuit that can be controlled by the Thermo-Optic Effect (TOE) and the Carrier Depletion Phenomenon (CDP). The methodology used integrates the most recent and classic studies of the mathematical and physical principles that govern these structures and materials, using analysis tools such as MATLAB and Python, with the aim of laying the theoretical foundations for the use of professional design tools. in our case, we will use Synopsys' Rsoft-CAD Layout, which implements advanced algorithms such as: Finite Difference Time Domain (FDTD), Beam Propagation Method (BPM), and Finite Element Method (FEM). In conclusion, a document will be presented that has the relevant theory of PICs and their control methods, as well as two functional solutions and their applications.
Digital assistant with artificial intelligence techniques
Publication . Dias, Dinis Rodrigues; Ferreira, Artur Jorge; Leite, Nuno Miguel da Costa de Sousa
Abstract
The design, implementation, and assessment of a modular Digital Assistant (DA), developed in Python, that can process natural language in speech and text, being optimized for the Windows desktop environment are presented in this dissertation. The DA performs tasks like retrieving weather data and launching applications, where the system combines Large Language Models (LLM) to interpret user requests and dynamically choose between conversational responses and function execution. To ensure modularity, extensibility, and maintainability, a layered architecture was used to organize the functionality, reasoning engine, conversation handling, and graphical user interface modules. To maintain responsiveness and user control even during lengthy operations, the assistant uses asynchronous execution, supports both text and voice input, and can output speech synthesis. The implementation places a strong emphasis on sound software engineering techniques, such as modular contracts, interface-first design, and reliable error handling. The secure handling of Application Programming Interface (API) keys and the lack of persistent memory protect privacy are also addressed. Experimental evaluation shows near real-time responses from contemporary LLM backends, sub-second latency for functionality modules, and high accuracy in differentiating between function calls and conversations. Additionally, qualitative validation verifies that the system satisfies its non-functional requirements for modularity, robustness, and user experience, and that the Graphical User Interface (GUI) is responsive and the speech features are usable. In conclusion, the project produces a useful, expandable, and intuitive digital assistant that connects conversational Artificial Intelligence (AI) and desktop task automation, providing a solid basis for upcoming improvements like cross-platform deployment, sophisticated speech recognition, and runtime model selection.