2023
Authors
Costa, M; Pereira, SC; Pedrosa, J; Mendonca, AM; Campilho, A;
Publication
2023 IEEE 7TH PORTUGUESE MEETING ON BIOENGINEERING, ENBENG
Abstract
Chest radiography is one of the most common imaging exams, but its interpretation is often challenging and timeconsuming, which has motivated the development of automated tools for pathology/abnormality detection. Deep learning models trained on large-scale chest X-ray datasets have shown promising results but are highly dependent on the quality of the data. However, these datasets often contain incorrect metadata and non-compliant or corrupted images. These inconsistencies are ultimately incorporated in the training process, impairing the validity of the results. In this study, a novel approach to detect non-compliant images based on deep features extracted from a patient position classification model and a pre-trained VGG16 model are proposed. This method is applied to CheXpert, a widely used public dataset. From a pool of 100 images, it is shown that the deep feature-based methods based on a patient position classification model are able to retrieve a larger number of non-compliant images (up to 81% of non-compliant images), when compared to the same methods but based on a pretrained VGG16 (up to 73%) and the state of the art uncertainty-based method (50%).
2023
Authors
Campos, TD; Barbosa, MLS; Martins, M; Pereira, FAM; de Moura, MFSF; Nguyen, Q; Zille, A; Dourado, N;
Publication
THEORETICAL AND APPLIED FRACTURE MECHANICS
Abstract
Bone cements based on poly(methylmethacrylate) (PMMA) are primarily used in joint replacement surgeries. In the fixation of joint replacement, the self-curing cement fills constitutes a very important interface. To under-stand and improve the interaction between cortical bone and bone cement it is essential to characterize the mechanical properties of cement-bone bonded joints in full detail. In this study, the end-notched flexure test was used in the context of pure mode II fracture characterisation of cement-bone bonded joints. A data reduction scheme based on crack equivalent concept was employed to overcome the difficulties inherent to crack length monitoring during damage propagation. A finite element method combined with a cohesive zone model was first used to validate numerically the adopted method. The procedure was subsequently applied to experimental results to determine the fracture toughness of cement-bone bonded joints under pure mode II loading. The consistency of the obtained results leads to the conclusion that the adopted procedure is adequate to carry out fracture characterisation of these joints under pure mode II loading. The innovative aspect of the present work lies in the application of cohesive zone modelling approach to PMMA-based cement-bone bonded joints.
2023
Authors
Gonçalves, G; Coelho, H; Monteiro, P; Melo, M; Bessa, M;
Publication
ACM COMPUTING SURVEYS
Abstract
The adoption of immersive virtual experiences (IVEs) opened new research lines where the impact of realism is being studied, allowing developers to focus resources on realism factors proven to improve the user experience the most. We analyzed papers that compared different levels of realism and evaluated their impact on user experience. Exploratorily, we also synthesized the realism terms used by authors. From 1,300 initial documents, 79 met the eligibility criteria. Overall, most of the studies reported that higher realism has a positive impact on user experience. These data allow a better understanding of realism in IVEs, guiding future R&D.
2023
Authors
Oliveira, C; Simoes, M; Bitencourt, L; Soares, T; Matos, MA;
Publication
ENERGIES
Abstract
Energy communities have been designed to empower consumers while maximizing the self-consumption of local renewable energy sources (RESs). Their presence in distribution systems can result in strong modifications in the operation and management of such systems, moving from a centralized operation to a distributed one. In this scope, this work proposes a distributed community-based local energy market that aims at minimizing the costs of each community member, accounting for the technical network constraints. The alternating direction method of multipliers (ADMM) is adopted to distribute the market, and preserve, as much as possible, the privacy of the prosumers' assets, production, and demand. The proposed method is tested on a 10-bus medium voltage radial distribution network, in which each node contains a large prosumer, and the relaxed branch flow model is adopted to model the optimization problem. The market framework is proposed and modeled in a centralized and distributed fashion. Market clearing on a day-ahead basis is carried out taking into account actual energy exchanges, as generation from renewable sources is uncertain. The comparison between the centralized and distributed ADMM approach shows an 0.098% error for the nodes' voltages. The integrated OPF in the community-based market is a computational burden that increases the resolution of the market dispatch problem by about eight times the computation time, from 200.7 s (without OPF) to 1670.2 s. An important conclusion is that the proposed market structure guarantees that P2P exchanges avoid the violation of the network constraints, and ensures that community agents' can still benefit from the community-based architecture advantages.
2023
Authors
Costa, Carolina; Fernandes, Sandra; Nakamura, Ingrid; Poínhos, Rui; Bruno M P M Oliveira;
Publication
Abstract
2023
Authors
Carneiro, D; Palumbo, G;
Publication
NEW TRENDS IN DISRUPTIVE TECHNOLOGIES, TECH ETHICS AND ARTIFICIAL INTELLIGENCE, DITTET 2023
Abstract
In recent years, the EU has been pushing forward ground-breaking legislation that covers new digital environments and services, with a strong focus on Ethics and AI. This includes legislation such as the Artificial Intelligence Act, the Digital Services Act or the General Data Protection Regulation. This legislation is, however, often written in very general and high-level terms, leaving a lot of space for interpretation, and a gap concerning how it could or should be implemented, realistically. In this paper we look specifically at the principle of Transparency in the Digital Services Act. Specifically, we discuss the requirements concerning Transparency in the regulation, we identify the gaps, and propose concrete measures that can be considered to facilitate and guide its implementation.
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