High-Current Double Pulse ECT Technique for Inspection of Ferromagnetic Materials

The detection of surface cracks of conductive materials that have a magnetic permeability higher than μ0, are usually made using the Magnetic Flux Leakage (MFL) technique. It requires the saturation of the specimen so that some magnetic flux lines escape the material when a defect is present. However, saturating the material can be very power consuming and if there is motion involved, eddy currents induced due to motion decrease or even null this method sensitivity as speed increases, which can be a disadvantage in cases such as railroad inspection. This work proposes a new technique to inspect the surface of ferromagnetic materials based on eddy currents. It is denominated high-current double pulse (Hi-CDP) ECT. The technique creates two consecutive pulses of currents (up to 1500 A) in a coil in the vicinity of the sample. Fig. 1 shows the simulation model used and the corresponding magnetic flux obtained in a point in the axis of a pancake coil (25 turns, id=15 mm, od=25 mm, heigh=10 mm), and in the vicinity of the sample material. The first pulse (starts at 0.1 ms) saturates the material, making it behave almost like a non-ferromagnetic material. The second pulse starts at 0.25 ms when the maximum current of the first pulse occurs (when the material is most saturated). When the second pulse occurs, eddy currents are induced. As the material is saturated, the ferromagnetic properties almost do not interfere with penetration depth and distribution of eddy currents, making it suitable for eddy current testing. Fig. 2 shows the derivative of the magnetic field obtained in a point located between the windings of the coil and the sample material, for a case without defect and in the presence of two similar defects with different depths (0.5 mm and 1.5 mm deep) in the vicinity of the point. It is possible to observe that the second current peak contains a perturbation that is different according to the defect. The signal derivative was chosen in order to distinguish the MFL from eddy currents perturbations

General purpose medical digital library definition

The need of an approach for the definition of a platform-independent medical digital library, using only 2 open-source tools, will be described. To test the need and the success of such an approach, a library will 3 be created, which can later be used in a larger scale as a general purpose digital medical tool, when comes 4 the need to evaluate an image. 5 As a first test, the library will be used in the development of a tool aimed to aid doctors in otoplasty 6 candidates' evaluation. This tool shall be developed and tested first on a mobile platform, so the potential 7 of the developed library can be tested on the most adverse situation. Also, the resulting library will be 8 license free, making easier the collaboration of others in development and integration with other software, 9 translating in a better spread of the library in medical practice. 10 CCS Concepts 11 • Medical imaging, mobile devices, digital medical tool. 12 Keywords 13 Medical imaging, open-source, image analysis software library, digital medical tool

Betões de elevado desempenho com nano-partículas de TiO2 e cinzas volantes : resistência mecânica, durabilidade e custo

Os betões de elevado desempenho apresentam vantagens várias sobre os betões correntes nomeadamente elevada resistência e durabilidade. Estes materiais permitem a execução de estruturas com menor quantidade de aço e com uma vida útil superior, fatores cruciais para a eco-eficiência daquelas. Apesar disso as publicações sobre betões com nano-partículas são escassas, representando apenas 1% do total de publicações em revista internacional sobre estes materiais. As publicações sobre betões de elevado desempenho com nano-partículas são ainda mais reduzidas. O presente artigo apresenta resultados de uma investigação experimental sobre a resistência mecânica e a durabilidade de betões de elevado desempenho contendo nano-partículas de TiO2 e cinzas volantes. Os parâmetros de durabilidade foram avaliados com recurso a ensaios de absorção de água por imersão e por capilaridade, ensaios de ultra-sons, resistividade elétrica, difusão de cloretos e resistência ao ataque químico. Os resultados mostram que betões com um teor crescente de nano-partículas de TiO2 evidenciam uma redução da durabilidade. Mostram também que betões com 1% de nano-partículas de TiO2 e substituição parcial de cimento Portland por 30% de cinzas volantes apresentam uma elevada resistência mecânica (C55/C67) a par de uma elevada durabilidade. Contudo as nano-partículas de TiO2 agravam de forma muito significativa o custo dos betões

Utilização de nano-partículas para a obtenção de betões de elevado desempenho

Os betões de elevado desempenho apresentam vantagens várias sobre os betões correntes nomeadamente elevada resistência e durabilidade. Estes materiais permitem a execução de estruturas com menor quantidade de aço e com uma vida útil superior, fatores cruciais para a ecoeficiência daquelas. Apesar disso as publicações sobre betões com nano-partículas são escassas, representando apenas 1% do total de publicações sobre estes materiais. As publicações sobre betões de elevado desempenho com nano-partículas são ainda mais reduzidas. O presente artigo apresenta resultados de uma investigação experimental sobre a resistência mecânica e a durabilidade de betões de elevado desempenho contendo nano-partículas de TiO2 e cinzas volantes. Os parâmetros de durabilidade foram avaliados com recurso a ensaios de absorção de água por imersão e por capilaridade, ensaio de ultra-sons, resistividade elétrica, difusão de cloretos e resistência ao ataque químico. Os resultados mostram que betões com um teor crescente de nano-partículas de TiO2 evidenciam uma redução da durabilidade. Os resultados mostram também que betões com 1% nanopartículas de TiO2 e substituição parcial de cimento Portland por 30% de cinzas volantes apresentam uma elevada resistência mecânica (C55/C67) a par de uma elevada durabilidade. Os resultados permitiram ainda detetar várias correlações estatisticamente significativas

The challenge of long-distance over-the-air wireless links in the ocean: a survey on water-to-water and water-to-land miot communication

Robust wireless communication networks are a cornerstone of the modern world, allowing data to be transferred quickly and reliably. Establishing such a network at sea, a Maritime Internet of Things (MIoT), would enhance services related to safety and security at sea, environmental protection, and research. However, given the remote and harsh nature of the sea, installing robust wireless communication networks with adequate data rates and low cost is a difficult endeavor. This paper reviews recent MIoT systems developed and deployed by researchers and engineers over the past few years. It contains an analysis of short-range and long-range over-the-air radio-frequency wireless communication protocols and the synergy between these two in the pursuit of an MIoT. The goal of this paper is to serve as a go-to guide for engineers and researchers that need to implement a wireless sensor network at sea. The selection criterion for the papers included in this review was that the implemented wireless communication networks were tested in a real-world scenario.cofunded by the project K2D: Knowledge and Data from the Deep to Space with reference POCI-01-0247-FEDER-045941, cofinanced by the European Regional Development Fund (ERDF), through the Operational Program for Competitiveness and Internationalization (COMPETE2020), and by the Portuguese Foundation for Science and Technology (FCT) under the MIT Portugal Program. This work is also cofinanced by national funds through FCT–Fundação para a Ciência e Tecnologia, I.P., under project SONDA (PTDC/EME-SIS/1960/2020). T.M. thanks FCT for grant SFRH/BD/145070/201

ECT characterization of a linear defect from multiple angle measurements

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An experimental investigation on nano-TiO2 and fly ash based high performance concrete

High performance concrete (HPC) offers several advantages over normal-strength concrete, namely, high mechanical strength and high durability. Therefore, HPC allows for concrete structures with less steel reinforcement and a longer service life, both of which are crucial issues in the eco-efficiency of construction materials. Nevertheless international publications on the field of concrete containing nanoparticles are scarce when compared to Portland cement concrete (around 1%) of the total international publications. HPC nanoparticle-based publications are even scarcer. This article presents the results of an experimental investigation on the mechanical properties and durability of HPC based on nano-TiO2 and fly ash. The durability performance was assessed by means of water absorption by immersion, water absorption by capillarity, ultrasonic pulse velocity, electric resistivity, chloride diffusion and resistance to sulphuric acid attack. The results show that the concretes containing an increased content of nano-TiO2 show decreased durability performance. The results also show that concrete with 1% nano-TiO2 and 30% fly ash as Portland cement replacement show a high mechanical strength (C55/C67) and a high durability. However, it should be noted that the cost of nano-TiO2 is responsible for a severe increase in the cost of concrete mixtures.(undefined

Wave profile and tide monitoring system for scalable implementation

A versatile, miniaturized, cost-effective, low-power wave profile and tide monitoring system, capable of long-term and scalable deployment, was developed to integrate pressure and temperature sensors in an RS485 network, for standalone operation with organized memory or real-time shared data monitoring. The pressure and temperature sensors are controlled by low-power microcontrollers, that communicate the data periodically to a datalogger, that depending on the application, store it in a removable SD card or send it to a server via Wi-Fi. The data is then analyzed to compensate for the loss in amplitude sensitivity according to the sensor’s depth. The wave profile can be sampled at a maximum rate of 100 Hz, with a 1 cm resolution. The system was tested successfully in real-life conditions, in rivers Douro and Cávado, and off the coast of Viana do Castelo.João Rocha was supported by the doctoral Grant PRT/BD/154322/2023 financed by the Portuguese Foundation for Science and Technology (FCT), and with funds from Portuguese State Budget, European Social Fund (ESF) and Por_Norte, under MIT Portugal Program. This work is co-funded by the projects K2D: Knowledge and Data from the Deep to Space (POCI-01-0247-FEDER-045941), SONDA (PTDC/EME-SIS/1960/2020), ATLÂNTIDA (NORTE-01-0145-FEDER-000040) and CMEMS - UIDB/04436/2020 and UIDP/04436/2020

Wave profile and tide monitoring system for scalable implementation

Apresentação de Poster em conferência Nacional.Presentation of a wave profile and tide monitoring system, with low-cost and low-power pressure sensors connected to a datalogger in a wired or acustic network

New insights on the impacts of e-waste towards marine bivalves: the case of the rare earth element Dysprosium

With the technological advances and economic development, the multiplicity and wide variety of applications of electrical and electronic equipment have increased, as well as the amount of end-of-life products (waste of electrical and electronic equipment, WEEE). Accompanying their increasing application, there is an increasing risk to aquatic ecosystems and inhabiting organisms. Among the most common elements present in WEEE are rare earth elements (REE) such as Dysprosium (Dy). The present study evaluated the metabolic and oxidative stress responses of mussels Mytilus galloprovincialis exposed to an increasing range of Dy concentrations, after a 28 days experimental period. The results obtained highlighted that Dy was responsible for mussel’s metabolic increase associated with glycogen expenditure, activation of antioxidant and biotransformation defences and cellular damage, with a clear loss of redox balance. Such effects may greatly impact mussel’s physiological functions, including reproduction capacity and growth, with implications for population conservation. Overall the present study pointed out the need for more research on the toxic impacts resulting from these emerging pollutants, especially towards marine and estuarine invertebrate species.publishe