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Publications

2023

Characterization of Functional Coatings on Cork Stoppers with Laser-Induced Breakdown Spectroscopy Imaging

Authors
Ferreira, MFS; Guimaraes, D; Oliveira, R; Lopes, T; Capela, D; Marrafa, J; Meneses, P; Oliveira, A; Baptista, C; Gomes, T; Moutinho, S; Coelho, J; da Silva, RN; Silva, NA; Jorge, PAS;

Publication
SENSORS

Abstract
Evaluating the efficiency of surface treatments is a problem of paramount importance for the cork stopper industry. Generically, these treatments create coatings that aim to enhance the impermeability and lubrification of cork stoppers. Yet, current methods of surface analysis are typically time-consuming, destructive, have poor representativity or rely on indirect approaches. In this work, the use of a laser-induced breakdown spectroscopy (LIBS) imaging solution is explored for evaluating the presence of coating along the cylindrical surface and in depth. To test it, several cork stoppers with different shaped areas of untreated surface were analyzed by LIBS, making a rectangular grid of spots with multiple shots per spot, to try to identify the correspondent shape. Results show that this technique can detect the untreated area along with other features, such as leakage and holes, allowing for a high success rate of identification and for its performance at different depths, paving the way for future industry-grade quality control solutions with more complex surface analysis.

2023

Non-parametric Gaussian process kernel DMD and LS-SVM predictors revisited A unifying approach

Authors
dos Santos, PL; Azevedo-Perdicoulis, TP; Salgado, PA;

Publication
IFAC PAPERSONLINE

Abstract
In this work, the prediction of a time series is formulated as a gaussian process regression, for different levels of noise. The gaussian regressor is translated into lower rank Dynamic Mode Decomposition methods that use kernels (K-DMD) - Kernel regression and Least Squares Support Vector Machines. The presented unified approach delivers an algorithm where the optimisation of the marginal likelihood function can be used to find the parameters of the kernel regression. The viability of the procedure is demonstrated on a chaotic series, with quite good adjustment results being obtained. Copyright (c) 2023 The Authors.

2023

Exploring Climate Change Data with R

Authors
Guimarães, N; Vehkalahti, K; Campos, P; Engel, J;

Publication
Statistics for Empowerment and Social Engagement: Teaching Civic Statistics to Develop Informed Citizens

Abstract
Climate change is an existential threat facing humanity and the future of our planet. The signs of global warming are everywhere, and they are more complex than just the climbing temperatures. Climate data on a massive scale has been collected by various scientific groups around the globe. Exploring and extracting useful knowledge from large quantities of data requires powerful software. In this chapter we present some possibilities for exploring and visualising climate change data in connection with statistics education using the freely accessible statistical programming language R together with the computing environment RStudio. In addition to the visualisations, we provide annotated references to climate data repositories and extracts of our openly published R scripts for encouraging teachers and students to reproduce and enhance the visualisations. © Springer Nature Switzerl and AG 2022.

2023

Electrohydraulic and Electromechanical Buoyancy Change Device Unified Vertical Motion Model

Authors
Carneiro, JF; Pinto, JB; de Almeida, FG; Cruz, NA;

Publication
ACTUATORS

Abstract
Depth control is crucial for underwater vehicles, not only to perform certain tasks that require the vehicle to be still at a given depth but also because most propeller-driven vehicles waste a considerable amount of energy to counteract the passively tuned positive buoyancy. The use of a variable buoyancy system (VBS) can effectively address these items, increasing the energetic efficiency and thus mission length. Achieving accurate depth controllers is, however, a complex task, since experimental controller development in sea or even in test pools is unpractical and the use of simulation requires accurate vertical motion models whose parameters might be difficult to obtain or measure. The development of simple, yet comprehensive, dynamic models for devices incorporating VBS is therefore of upmost importance, as well as developing procedures that allow a simple determination of their parameters. This work contributes to this field by deriving a unified model for the vertical motion of a VBS actuated device, irrespective of the specific technological actuation solution employed, whether it be electromechanical or electrohydraulic. A concise analysis of the open-loop stability of the unified model is presented and a straightforward yet efficient procedure for identifying several of its parameters is introduced. This identification procedure is designed to be convenient and can be carried out in shallow waters, such as test pools, while its results are applicable to the deeper water model as well. To validate the procedure, experimental values obtained from an electromechanical VBS actuated device are used. Closed-loop control of the electromechanical VBS actuated device is conducted through simulation and experimental tests. The results confirm the effectiveness of the proposed unified model and the parameter identification methodology.

2023

Discovery Science

Authors
Bifet, A; Lorena, AC; Ribeiro, RP; Gama, J; Abreu, PH;

Publication
Lecture Notes in Computer Science

Abstract

2023

Integrating Security and Privacy Mechanisms with Fast Health Interoperability Resources (FHIR), a Scoping Review

Authors
Pavão, J; Bastardo, R; Rocha, NP;

Publication
Lecture Notes in Networks and Systems

Abstract
The scoping review reported by this article aimed to analyse how security and privacy mechanism are being integrated with Fast Health Interoperability Resources (FHIR). An electronic search was conducted, and 37 studies were included in the review. The results show that 19 studies (i.e., more than half of the included studies) reported on the use of blockchain technology to (i) assure secure data sharing, (ii) provide secure Personal Health Records, (iii) support authentication and auditing mechanisms, (iv) support smart legal contracts, and (v) monitor the access to clinical data. The remainder 18 articles reported on the implementation of security and privacy mechanisms related to (i) data security at transmission, (ii) data security at storage, (iii) access control; (iv) data anonymization, and (v) management of informed consents. © 2023, The Author(s), under exclusive license to Springer Nature Switzerland AG.

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