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Publications

2022

The CirCor DigiScope Dataset: From Murmur Detection to Murmur Classification

Authors
Oliveira, J; Renna, F; Costa, PD; Nogueira, M; Oliveira, C; Ferreira, C; Jorge, A; Mattos, S; Hatem, T; Tavares, T; Elola, A; Rad, AB; Sameni, R; Clifford, GD; Coimbra, MT;

Publication
IEEE JOURNAL OF BIOMEDICAL AND HEALTH INFORMATICS

Abstract

2022

An Analytic Hierarchy Process for Selecting Battery Equalization Methods

Authors
Dias, BMD; da Silva, CT; Araujo, RE; de Castro, R; Pellini, EL; Pinto, C; Lagana, AAM;

Publication
ENERGIES

Abstract
Batteries have been the predominant energy storage system used in electric vehicles. Battery packs have a large number of cells that develop charge, thermal, and capacity imbalances over time, limiting the power, range, and lifetime. Electronic battery management and state of charge (SoC) equalization methods are necessary to mitigate such imbalances. Today, it is possible to find a wide range of battery equalization methods in the literature, but how to decide which of these methods should be applied in practice? This paper compares 24 SoC equalization circuits that are typically found in automotive applications. We employ an analytic hierarchy process (AHP) approach to rank these equalization circuits according to multiple decision criteria (energy efficiency, equalization speed, implementation and control simplicity, hardware size, and total price). We also prepared a survey to collect design preferences from multiple battery balancing experts from around the world in order to better understand the relative importance of different criteria. The obtained results confirm that automotive engineers continue to favor passive balancing methods because of their low price, small PCB size, and implementation simplicity-despite the energy efficiency benefits of active balancing.

2022

Modelling the Heating Process in the Transient and Steady State of an In Situ Tape-Laying Machine Head

Authors
Rodrigues, JD; Goncalves, PT; Pina, L; de Almeida, FG;

Publication
JOURNAL OF MANUFACTURING AND MATERIALS PROCESSING

Abstract
As the use of composite materials increases, the search for suitable automated processes gains relevance for guaranteeing production quality by ensuring the uniformity of the process, minimizing the amount of scrap generated, and reducing the time and energy consumption. Limitations on production by traditional means such as hand lay-up, vacuum bagging, and in-autoclave methods tend not to be as efficient when the size and shape complexity of the part being produced increases, motivating the search for alternative processes such as automated tape laying (ATL). This work aims to describe the process of modelling and simulating a composite ATL with in situ consolidation by characterizing the machine elements and using the finite differences method in conjunction with energy balances in order to create a digital twin of the process for further control design. The modelling approach implemented is able to follow the process dynamics when changes are made to the heating element and to predict the composite material temperature response, making it suitable for use as a digital twin of a production process using an ATL machine.

2022

Optical Strain Gauge Prototype Based on a High Sensitivity Balloon-like Interferometer and Additive Manufacturing

Authors
Cardoso, VHR; Caldas, P; Giraldi, MTR; Frazao, O; Costa, JCWA; Santos, JL;

Publication
SENSORS

Abstract
An optical strain gauge based on a balloon-like interferometer structure formed by a bent standard single-mode fiber combined with a 3D printer piece has been presented and demonstrated, which can be used to measure displacement. The interferometer has a simple and compact size, easy fabrication, low cost, and is repeatable. The sensor is based on the interference between the core and cladding modes. This is caused by the fiber's curvature because when light propagates through the curved balloon-shaped interferometer region, a portion of it will be released from the core limitation and coupled to the cladding. The balloon has an axial displacement as a result of how the artwork was constructed. The sensor head is sandwiched between two cantilevers such that when there is a displacement, the dimension associated with the micro bend is altered. The sensor response as a function of displacement can be determined using wavelength shift or intensity change interrogation techniques. Therefore, this optical strain gauge is a good option for applications where structure displacement needs to be examined. The sensor presents a sensitivity of 55.014 nm for displacement measurements ranging from 0 to 10 mm and a strain sensitivity of 500.13 pm/mu epsilon.

2022

Expert Validation of the ICT Accessibility Requirements Tool Prototype

Authors
Martins, M; Godinho, F; Goncalves, P; Goncalves, R;

Publication
UNIVERSAL ACCESS IN HUMAN-COMPUTER INTERACTION: NOVEL DESIGN APPROACHES AND TECHNOLOGIES, UAHCI 2022, PT I

Abstract
The Accessibility Requirements Tool for Information and Communication Technologies (FRlATIC) was developed within the work of a doctoral project, at the University of Tras-os-Montes and Alto Douro, and may be used at various stages of public procurement processes as well as projects and developments that include ICT products and services. This tool helps to consult, determine and assess the accessibility requirements for ICT products and services in European Standard EN 301 549 supporting the legislation in the field of public procurement for the countries of the European Union - Directive 2014/24/EU. This study focuses on the validation of the FRATIC prototype with 25 experts in the areas of accessibility, assistive technologies and public procurement, by conducting semi-structured interviews on this research subject and the FRATIC tool in particular, which were conducted after performing usability tests with the tool. A thematic analysis method was used to assess the qualitative data from the interviews.

2022

A formal treatment of the role of verified compilers in secure computation

Authors
Almeida, JCB; Barbosa, M; Barthe, G; Pacheco, H; Pereira, V; Portela, B;

Publication
JOURNAL OF LOGICAL AND ALGEBRAIC METHODS IN PROGRAMMING

Abstract
Secure multiparty computation (SMC) allows for complex computations over encrypted data. Privacy concerns for cloud applications makes this a highly desired technology and recent performance improvements show that it is practical. To make SMC accessible to non-experts and empower its use in varied applications, many domain-specific compilers are being proposed. We review the role of these compilers and provide a formal treatment of the core steps that they perform to bridge the abstraction gap between high-level ideal specifications and efficient SMC protocols. Our abstract framework bridges this secure compilation problem across two dimensions: 1) language-based source- to target-level semantic and efficiency gaps, and 2) cryptographic ideal- to real-world security gaps. We link the former to the setting of certified compilation, paving the way to leverage long-run efforts such as CompCert in future SMC compilers. Security is framed in the standard cryptographic sense. Our results are supported by a machine-checked formalisation carried out in EasyCrypt. © 2021 Elsevier Inc.

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