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Publicações

2023

Construction of an Algorithm for Three-Dimensional Bone Segmentation from Images Obtained by Computational Tomography

Autores
Barbosa, M; Renna, F; Dourado, N; Costa, R;

Publicação
Studies in Computational Intelligence

Abstract
This paper proposes a tool that extracts data from computational tomography (CT) scans of long bones, applies filters to allow a distinction between cortical and cancellous tissue, and converts the tissues into a three-dimensional (3D) model that can be used to generate finite element meshes. In order to identify the best segmentation technique for the problem under study, cortical, cancellous and medulla tissue segmentation was tested based on image histogram information, simple Hounsfield scale (HU) information, HU scale information with morphological operator filters, and active contour methods (active contour, random walker segmentation and findContours). These segmentations were evaluated qualitatively through a visual comparison and quantitatively through the calculation of the Dice Coefficient (DICE) and Mean-Squared Error (MSE) parameters. The developed algorithm presents a Dice higher than 0.95 and a MSE lower than 0.01 for cortical tissue segmentation, which allows it to be used as a bone characterization method. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023.

2023

Two-Stage Framework for Faster Semantic Segmentation

Autores
Cruz, R; Silva, DTE; Goncalves, T; Carneiro, D; Cardoso, JS;

Publicação
SENSORS

Abstract
Semantic segmentation consists of classifying each pixel according to a set of classes. Conventional models spend as much effort classifying easy-to-segment pixels as they do classifying hard-to-segment pixels. This is inefficient, especially when deploying to situations with computational constraints. In this work, we propose a framework wherein the model first produces a rough segmentation of the image, and then patches of the image estimated as hard to segment are refined. The framework is evaluated in four datasets (autonomous driving and biomedical), across four state-of-the-art architectures. Our method accelerates inference time by four, with additional gains for training time, at the cost of some output quality.

2023

Short Pulse Generation in Erbium-Doped Fiber Lasers Using Graphene Oxide as a Saturable Absorber

Autores
Monteiro, CS; Perez Herrera, RA; Silva, SO; Frazão, O;

Publicação
Proceedings of the 11th International Conference on Photonics, Optics and Laser Technology, PHOTOPTICS 2023, Lisbon, Portugal, February 16-18, 2023.

Abstract
The use of graphene oxide (GO) as a saturable absorber for short pulses generation in an Erbium-doped fiber laser was studied and demonstrated. The saturable absorber consisted of a thin GO film, with a high concentration of monolayer GO flakes, spray-coated on the end face of a ferrule-connected fiber. By including the saturable absorber in the laser cavity and controlling the intra-cavity polarization, the generation of shortpulsed light was achieved under mode-locking and Q-switching operations. Under mode-locking operation, it was observed a pulse train with a fundamental repetition rate of 1.48 MHz, with a working wavelength centered at 1564.4 nm. In the Q-switch operation, a pulse train with a 12.7 kHz repetition rate and a 14.3 µs pulse duration was attained for a 230-mA pump current. Further investigation showed a linear dependence of the repetition rate with the pump power, attaining frequencies between 12.7 and 14.4 kHz. © 2023 by SCITEPRESS - Science and Technology Publications, Lda.

2023

Preface

Autores
Almeida, JP; Geraldes, CS; Lopes, IC; Moniz, S; Oliveira, JF; Pinto, AA;

Publicação
Springer Proceedings in Mathematics and Statistics

Abstract
[No abstract available]

2023

Deep Minutiae Fingerprint Extraction Using Equivariance Priors

Autores
Gouveia, M; Castro, E; Rebelo, A; Cardoso, JS; Patrão, B;

Publicação
Proceedings of the 16th International Joint Conference on Biomedical Engineering Systems and Technologies, BIOSTEC 2023, Volume 4: BIOSIGNALS, Lisbon, Portugal, February 16-18, 2023.

Abstract

2023

Hybrid IGDT-stochastic self-scheduling of a distributed energy resources aggregator in a multi-energy system

Autores
Vahid-Ghavidel, M; Shafie-khah, M; Javadi, MS; Santos, SF; Gough, M; Quijano, DA; Catalao, JPS;

Publicação
ENERGY

Abstract
The optimal management of distributed energy resources (DERs) and renewable-based generation in multi -energy systems (MESs) is crucial as it is expected that these entities will be the backbone of future energy sys-tems. To optimally manage these numerous and diverse entities, an aggregator is required. This paper proposes the self-scheduling of a DER aggregator through a hybrid Info-gap Decision Theory (IGDT)-stochastic approach in an MES. In this approach, there are several renewable energy resources such as wind and photovoltaic (PV) units as well as multiple DERs, including combined heat and power (CHP) units, and auxiliary boilers (ABs). The approach also considers an EV parking lot and thermal energy storage systems (TESs). Moreover, two demand response (DR) programs from both price-based and incentive-based categories are employed in the microgrid to provide flexibility for the participants. The uncertainty in the generation is addressed through stochastic pro-gramming. At the same time, the uncertainty posed by the energy market prices is managed through the application of the IGDT method. A major goal of this model is to choose the risk measure based on the nature and characteristics of the uncertain parameters in the MES. Additionally, the behavior of the risk-averse and risk -seeking decision-makers is also studied. In the first stage, the sole-stochastic results are presented and then, the hybrid stochastic-IGDT results for both risk-averse and risk-seeker decision-makers are discussed. The pro-posed problem is simulated on the modified IEEE 15-bus system to demonstrate the effectiveness and usefulness of the technique.

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