Repositório RCAAP

É objetivo deste trabalho, no âmbito de agilizar alterações às condições do processo de destilação para a produção de determinados produtos com propriedades definidas, simular o funcionamento das colunas T-2001 (coluna atmosférica) e T-2002 (coluna a vácuo) da unidade de destilação da Fábrica de Óleos Base da Refinaria de Matosinhos. Numa primeira fase procedeu-se ao levantamento das condições operatórias e modo de funcionamento das colunas bem como das características das correntes de saída laterais a saber: nafta, petróleo ou white spirit, gasóleo respeitantes à T-2001 e LVGO, Spindle, 100SN, 150SN, 500SN respeitantes à T-2002. Após o levantamento de toda a informação necessária para a realização da calibração do processo real no simulador, fez-se uma comparação entre os resultados das curvas de destilação segundo a norma ASTM D86 obtidas pelo Aspen Plus e as curvas de destilação obtidas nos ensaios realizados pelo laboratório da empresa, para cada produto da unidade de destilação da FOB, tendo-se dado particular atenção aos resultados da coluna de vácuo. Posto isto, obtiveram-se resultados relativamente satisfatórios, verificando-se as maiores diferenças entre os resultados para o LVGO e para o 500SN. Conclui-se que o aumento do número total de pratos da coluna de vácuo não afeta significativamente os resultados das curvas de destilação dos produtos da mesma e que o ajuste da curva TBP afasta a mesma da realidade da empresa, não sendo um procedimento a adotar. A aplicação de especificações de design na coluna, melhoram em geral os desvios entre os dados do simulador e do laboratório, tendo um efeito contrário no caso dos overlaps e nos caudais de saída dos produtos laterais da coluna de vácuo. Com a finalização do presente trabalho, obteve-se um modelo representativo da unidade de destilação da empresa que necessita ainda de alguns ajustes, para que possa ser usado como modelo de previsão em ciclos de operação onde se procure maximizar o rendimento de um determinado óleo base.

Com o presente trabalho pretende-se estudar sistemas de monitorização do comportamento de estruturas, com especial incidência nas estruturas de betão. Considera-se fundamental o conhecimento das potencialidades e limitações dos sistemas de medição actualmente existentes, de modo a permitir a sua correcta aplicação às estruturas, e consequente análise e interpretação do comportamento estrutural. A dissertação começa por apresentar uma descrição geral dos sistemas de monitorização de estruturas; introduzem-se os conceitos e a terminologia associados à metrologia e à caracterização dos instrumentos de medição, incidindo de modo particular sobre os instrumentos correntemente utilizados nas operações de monitorização. Em particular referem-se os instrumentos clássicos destinados à medição do deslocamento, da extensão, da temperatura, da pressão e da inclinação. O advento dos sensores de fibra óptica, e em particular dos sensores de Bragg, com características muito particulares de funcionamento, justificam uma referência especial na dissertação. Estes sensores têm sido aplicados com sucesso na monitorização de diversas estruturas, nomeadamente pontes e barragens, permitindo obter informação essencial acerca do seu comportamento ao longo do tempo. Descreve-se a aplicação pelo autor de sistemas de monitorização a estruturas de betão armado e/ou pré-esforçado, nomeadamente a duas passagens hidraúlicas, a uma ponte e a um viaduto. Relativamente a cada caso apresentado, descrevem-se as características das estruturas e do sistema de monitorização adoptado. Apresenta-se ainda uma interpretação sumária dos valores medidos em algumas dessas aplicações. Procede-se à análise do comportamento de uma das estruturas instrumentadas com base na medição efectuada em obra. Exemplifica-se deste modo as potencialidades dos sistemas de monitorização na interpretação do comportamento estrutural. A encerrar este trabalho, tecem-se algumas considerações genéricas acerca do trabalho realizado e apontam-se algumas sugestões tendo em vista o futuro desenvolvimento do tema.

A madeira é um recurso natural e uma das matérias-primas mais utilizadas. É a base de um dos tradicionais setores industriais portugueses, com forte imponência a nível global. Devido ao seu alargado leque de aplicações, este material, conta como a base para variadíssimos projetos, que requerem o aparecimento de produtos que aliem a inovação e a criatividade de forma assegurar a sua crescente procura. É neste sentido que o trabalho descrito neste artigo se torna de grande relevo, pois prima pela preocupação ambiental, desenvolvimento empresarial e inovação no ramo industrial. Neste projeto procedeu-se à síntese e otimização de diferentes pigmentos fosforescentes que foram posteriormente aplicados na formulação de um novo revestimento para a madeira. Este novo revestimento permitirá a valorização deste material de construção que é tão apreciado pelos consumidores acrescentando-lhe caraterísticas únicas e inovadoras.

The energy sector is one of the pillars of growth and development for industries and it has been increasing in the last decades. Due to the need of rationalizing energy in industries, the concept of energy efficiency arises. For a rational use of energy, it was created strategies and measures to reduce energy consumptions in a sustainable way – social, economic and environmental. To analyze these consumptions, this paper contains a case study of an energy intensive industrial installation. This study consists of analyzing all the energy consumptions of the installation, through the obtained values of energy indicators.

This letter studies the use of Unmanned Aerial Vehicles (UAVs) in Internet-of-Things (IoT) networks, where the UAV with microwave power transfer (MPT) capability is employed to hover over the area of interest, charging IoT nodes remotely and collecting their data. Scheduling MPT and data transmission is critical to reduce the data packet loss resulting from buffer overflows and channel fading. In practice, the prior knowledge of the battery level and data queue length of the IoT nodes is not available at the UAV. A new onboard double Q-learning scheduling algorithm is proposed to optimally select the IoT node to be interrogated for data collection and MPT along the flight trajectory of the UAV, thereby minimizing asymptotically the packet loss of the IoT networks. Simulations confirm the superiority of our algorithm to Q-learning based alternatives in terms of packet loss and learning efficiency/speed.

O novo Manual ITED 4, que entrou em vigor a 01 de abril 2020, apresenta soluções inovadoras e simplifica alguns procedimentos com o objetivo de melhorar a eficiência e a adaptabilidade das infraestruturas de telecomunicações aos avanços tecnológicos. No novo Manual ITED 4 é possível verificar algumas alterações nos requisitos das caixas e armários para as infraestruturas de telecomunicações - nomeadamente ao nível das dimensões mínimas, dos equipamentos a instalar nos armários - bem como o aparecimento de novas caixas como, por exemplo, a CAM – Caixa de Acesso Multioperador. Tendo como foco principal o cumprimento dos requisitos normativos, aliado a uma capacidade inovadora no desenvolvimento de produtos, a Quitérios dispõe de soluções que respondem aos requisitos do novo Manual ITED 4.

As redes de telecomunicações são para as empresas um investimento estratégico que se pretende “future-proof”. O investimento em redes de alto débito que permitam garantir a incorporação de serviços futuros com exigência de elevada largura de banda é assim crucial. Assegurar que a infraestrutura é um meio seguro, de elevada fiabilidade assume também fator decisivo. A diferenciação em mercados competitivo, a satisfação das expetativas dos utilizadores, consequente eficiência, produtividade e fidelização no caso por exemplo do sector da hospitalidade, são outros fatores determinantes. E por último, mas não menos importante, os aspetos económicos relativos ao investimento (CAPEX) e custos operacionais (OPEX) são naturalmente requisitos de elevada preponderância.

Fazem parte das ITED de um edifício: • os espaços para a instalação das redes de tubagem; • as redes de tubagem; • os sistemas de cablagem. A existência de uma rede de tubagens comum, que inicialmente poderá estar vazia, permite aos distintos operadores proporcionarem o seu serviço a cada fração, de uma maneira racional, económica e que não desmerece a estética do edifício. Com o objetivo de facilitar o acesso aos vários serviços de telecomunicações, dos vários operadores, a Unex oferece sistemas de condução de cabos flexíveis com as suas calhas em material isolante.

O Novo Manual ITED 4 em vigor desde o dia 01 de abril de 2020 traz alterações significativas relativamente à edição ITED 3 anterior, sendo estas relevantes no que refere ao dimensionamento da tecnologia de cabo coaxial. O Cabo Coaxial é o elemento fundamental de uma rede de S/MATV ou CATV, sendo o responsável pela transmissão dos sinais de radio frequência. A atenuação que lhe é associada deverá ser a mais baixa possível, de forma a garantir a transmissão do sinal protelando a inclusão de etapas de amplificação na rede.

A tecnologia PoE (Power Over Ethernet) permite a transmissão de energia elétrica e de dados, em simultâneo, através do cabo de pares de cobre, eliminando a necessidade de infraestrutura elétrica, minimizando os custos de instalação. O conceito de Power Over Ethernet está forçosamente relacionado com Alexander Bell e a telefonia analógica, uma vez que o telefone é definido como um aparelho eletroacústico que permite a transformação de energia acústica em energia elétrica no emissor, e a transformação dessa energia elétrica em acústica no recetor; assim, é possível a troca de informação, falada e ouvida, entre dois ou mais assinantes. O sinal elétrico era comutado por uma central telefónica analógica que gerava uma corrente de chamada para uma linha analógica, linha essa que utilizava o cabo de cobre como meio de transmissão.

Industry 4.0 and Autonomous Driving are emerging resource-intensive distributed application domains that deal with open and evolving environments. These systems are subject to stringent resource, timing, and other non-functional constraints, as well as frequent reconfiguration. Thus, real-time behavior must not preclude operational flexibility. This combination is motivating ongoing efforts within the Time Sensitive Networking (TSN) standardization committee to define admission control mechanisms for Ethernet. Existing mechanisms in TSN, like those of AVB, its predecessor, follow a distributed architecture that favors scalability. Conversely, the new mechanisms envisaged for TSN (IEEE 802.1Qcc) follow a (partially) centralized architecture, favoring short reconfiguration latency. This paper shows the first quantitative comparison between distributed and centralized admission control architectures concerning reconfiguration latency. Here, we compare AVB against a dynamic real-time reconfigurable Ethernet technology with centralized management, namely HaRTES. Our experiments show a significantly lower latency using the centralized architecture. We also observe the dependence of the distributed architecture in the end nodes' performance and the benefit of having a protected channel for the admission control transactions.

Brain cancer is one of the most dominant causes of cancer death; the best way to diagnose and treat brain tumors is to screen early. Magnetic Resonance Imaging (MRI) is commonly used for brain tumor diagnosis; however, it is a challenging problem to achieve higher accuracy and performance, which is a vital problem in most of the previously presented automated medical diagnosis. In this paper, we propose a Hybrid Two-Track U-Net(HTTU-Net) architecture for brain tumor segmentation. This architecture leverages the use of Leaky Relu activation and batch normalization. It includes two tracks; each one has a different number of layers and utilizes a different kernel size. Then, we merge these two tracks to generate the final segmentation. We use the focal loss, and generalized Dice (GDL), loss functions to address the problem of class imbalance. The proposed segmentation method was evaluated on the BraTS’2018 datasets and obtained a mean Dice similarity coefficient of 0.865 for the whole tumor region, 0.808 for the core region and 0.745 for the enhancement region and a median Dice similarity coefficient of 0.883, 0.895, and 0.815 for the whole tumor, core and enhancing region, respectively. The proposed HTTU-Net architecture is sufficient for the segmentation of brain tumors and achieves highly accurate results. Other quantitative and qualitative evaluations are discussed, along with the paper. It confirms that our results are very comparable expert human-level performance and could help experts to decrease the time of diagnostic.

Vehicle-to-Vehicle (V2V) communication aims to improve road safety by periodic exchange of Hello messages. Nowadays, the Internet of Things (IoT) is widely used to solve city transportation problems by employing multihop-based V2V communication. In IoT-based vehicular ad-hoc networks (VANETs), devices are interconnected with various hardware and software, so the privacy of data, temporal, and location will be at risk due to unauthorized manipulation, especially at intersections in congested urban areas. To address these concerns in IoT-based VANETs, we proposed a Smart Energy-based Source Location Privacy Preservation (SESLPP) technique for sustainable urban city roads (i.e., Intersections). The proposed SESLPP protects the source location privacy while maintaining an accurate reputation based on specific parameters such as trust, speed, distance, and acceleration. A selected node based on these parameters forwards messages and acts as a phantom node to improve the source location privacy within their communication range. The selection of a phantom node is based on a set of parameters, which makes it a multi-criteria decision problem. In this paper, a multi-criteria decision tool known as Analytical Network Process (ANP) has been used for optimal phantom node selection that improves the source location privacy in an urban scenario by considering intersections. We considered the same parameters (trust, speed, distance, and acceleration) that was used for highway scenario with proper adjustment of their values for an urban area (cross-road intersection point). The proposed SESLPP provides an optimal platform for smart city communication networks.

This paper addresses the control of a fleet of unmanned aerial systems (UAVs), termed as drones, for flight formation problems. Getting drones to fly in formation is a relevant problem to be solved when cooperative cargo transportation is desired. A general approach for this problem considers the coordination of a fleet of UAVs, by fusing all information coming from several individual sensors posed on each UAVs. However, this approach induces a high cost as every UAV should have its advanced perception system. As an alternative, this paper proposes the use of a single perception system by a fleet composed of several elementary drones (workers) with primitive low-cost sensors and a leader drone carrying a 3D perception source. We propose a Quadral-Fuzzy approach to ensure that all drones fly in formation and will not collide with each other or with environment obstacles. We also develop a new way to compute potential fields based on possibility fuzzy (fuzziness) measure with the focus of avoiding collisions between the drones. The proposed approach encompasses four high-coupled intelligent controllers that respectively control the leader and worker drones' motion and implement obstacle and collision avoidance procedures. Simulation results using a fleet of four aerial drones are presented, showing the potential for solving usual problems to flights in formation, such as dodging obstacles, avoiding collisions between the drones, among others.

In this entry, we present an overview on the use of service-oriented architecture and Web services in developing robotics applications and software integrated with the Internet and the Cloud. This is a recent trend that emerged since 2010 from the concept of cloud robotics, which leverages the use of cloud infrastructures for robotics applications following a service-oriented architecture approach. In particular, we distinguish two main categories: (i) virtualization of robotics systems and (ii) computation offloading from robots to cloud-based services. We discuss the main approaches proposed in the literature to design robotics systems through the Web and their integration to the cloud through service-oriented computing framework.

The urban water cycle concept demonstrates the connectivity and interdependence of urban water resources and human activities, and the need for integrated sustainable management studies and approaches. The role of climate, geology, geo-morphology, land-use/cover, hydrogeochemistry, hydraulics, human activities among other features is significant in urban areas. In addition, land-use development has a stronger influence on terrestrial hydrology than climate variability. The need for provision of safe water, sanitation and drainage systems is key elements to consider for the groundwater resources in complex urban environments. In recent years, a new focus has emerged, addressing issues on integrated GIS mapping stud-ies on urban water supply systems, particularly in historical cities. To illustrate that approach the Porto urban area (NW Portugal) was selected. This work presents a comprehensive study to demonstrate the key importance of urban groundwater studies, as well as the evaluation of the Urban Infiltration Potential Index and the potential groundwater yields that might be available for non-potable uses, such as irrigation of parks and lawns, street cleaning and firefighting. This strategy is useful for the planning and management of urban groundwater abstraction in an equitable and sustainable manner.

Disposable sensors are low-cost and easy-to-use sensing devices intended for short-term or rapid single-point measurements. The growing demand for fast, accessible, and reliable information in a vastly connected world makes disposable sensors increasingly important. The areas of application for such devices are numerous, ranging from pharmaceutical, agricultural, environmental, forensic, and food sciences to wearables and clinical diagnostics, especially in resource-limited settings. The capabilities of disposable sensors can extend beyond measuring traditional physical quantities (for example, temperature or pressure); they can provide critical chemical and biological information (chemo- and biosensors) that can be digitized and made available to users and centralized/decentralized facilities for data storage, remotely. These features could pave the way for new classes of low-cost systems for health, food, and environmental monitoring that can democratize sensing across the globe. Here, a brief insight into the materials and basics of sensors (methods of transduction, molecular recognition, and amplification) is provided followed by a comprehensive and critical overview of the disposable sensors currently used for medical diagnostics, food, and environmental analysis. Finally, views on how the field of disposable sensing devices will continue its evolution are discussed, including the future trends, challenges, and opportunities.

Honey was the main sweetening agent in the ancient world; it is mentioned in literary sources and archaeologically documentedall over the Mediterranean basin. Its production extended throughout different parts of the Roman Empire, with importanteconomic impacts on family economies, both as a foodstuff and as a commercial product. This paper focuses on the chromato-graphic analysis of Roman Iberian honeypots and ceramic beehives, identifying tracer characteristics from ancient honey insherds from seven honeypots and three beehives. The obtained results present an important contribution to the knowledge of thelocal Roman Iberian economy, particularly relating to the production, transport and trade of honey in locally manufacturedceramic containers.

Children, an important vulnerable group, spend most of their time at schools (up to 10 h per day, mostly indoors) and the respective air quality may significantly impact on children health. Thus, this work reviews the published studies on children biomonitoring and environmental exposure to particulate matter (PM) and polycyclic aromatic hydrocarbons (PAHs) at school microenvironments (indoors and outdoors), major sources and potential health risks. A total of 28, 35, and 31% of the studies reported levels that exceeded the international outdoor ambient air guidelines for PM10, PM2.5, and benzo(a)pyrene, respectively. Indoor and outdoor concentrations of PM10 at European schools, the most characterized continent, ranged between 7.5 and 229 μg/m3 and 21-166 μg/m3, respectively; levels of PM2.5 varied between 4 and 100 μg/m3 indoors and 6.1-115 μg/m3 outdoors. Despite scarce information in some geographical regions (America, Oceania and Africa), the collected data clearly show that Asian children are exposed to the highest concentrations of PM and PAHs at school environments, which were associated with increased carcinogenic risks and with the highest values of urinary total monohydroxyl PAH metabolites (PAH biomarkers of exposure). Additionally, children attending schools in polluted urban and industrial areas are exposed to higher levels of PM and PAHs with increased concentrations of urinary PAH metabolites in comparison with children from rural areas. Strong evidences demonstrated associations between environmental exposure to PM and PAHs with several health outcomes, including increased risk of asthma, pulmonary infections, skin diseases, and allergies. Nevertheless, there is a scientific gap on studies that include the characterization of PM fine fraction and the levels of PAHs in the total air (particulate and gas phases) of indoor and outdoor air of school environments and the associated risks for the health of children. There is a clear need to improve indoor air quality in schools and to establish international guidelines for exposure limits in these environments.

Chayote (Sechium edule) has gained widespread consuming acceptance and recognized by its nutritional and bio-functional properties. The present review surveys and describes the current findings about the nutritional, phytochemical and pharmacological properties of chayote and identifies opportunities for further research. It also discusses chayote's versatile utility in nutrition, as a functional ingredient in food, cosmetic and pharmaceutical industries, as well as in nanotechnology and biotechnological processes. It was concluded that although the pharmacological properties of chayote are currently well-established, only a few reports have been conducted on the isolation and identification of individual chemical constituents, and similarly, only a few in vivo studies have been conducted to assess their biological efficacy. In addition, the valorisation of the underutilized chayote by-products can be an important aspect in waste management from both economic and environmental standpoints. Thus, the recovery and utilization of valuable compounds from chayote is an important challenge for scientists.