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Publications

2025

Comparative analysis of cybersecurity artificial intelligence frameworks

Authors
Almeida, FL;

Publication
Information Security Journal: A Global Perspective

Abstract

2025

Electromechanical Characterization and Experimental Sensor Modeling of Thermoformed FEP Piezoelectrets for Dynamic Force Environments

Authors
Ginja, GA; Neto, MC; Moreira, MMAC; Amorim, MLM; Tita, V; Altafim, RAP; Altafim, RAC; Correia, MV; Queiroz, AAA; Siqueira, AAG; Do Carmo, JPP;

Publication
IEEE SENSORS JOURNAL

Abstract
This study explores the design, fabrication, and electromechanical characterization of thermoformed tubular Teflon piezoelectrets for force measurement applications. Piezoelectrets, a subclass of electrets, leverage engineered dipole configurations within charged internal cavities to exhibit piezoelectric properties. Using fluorinated ethylene propylene (FEP) films, tubular structures were fabricated through thermal lamination and subsequently polarized to form highly sensitive and flexible piezoelectrets. The electrical response was characterized by controlled impact tests, sinusoidal stationary force inputs using a shaker system and an instrumented insole to evaluate the piezoelectret in a real dynamic environment. The impact test revealed that the piezoelectret exhibits a rapid response time of 20 ms with a maximum voltage amplitude of +/- 3 V. The frequency-domain analysis identified primary and secondary bandpass ranges, with peak sensitivity observed at 400 Hz. The stationary test with a shaker showed a steady sensitivity of 53.87 mV/N for signals within the 200- and 700-Hz bandwidths.

2025

Study the Capacity of Deep Learning Techniques Information Generalization Using Capsule Endoscopic Images

Authors
Macedo, E; Araujo, H; Abreu, PH;

Publication
PATTERN RECOGNITION: ICPR 2024 INTERNATIONAL WORKSHOPS AND CHALLENGES, PT V

Abstract
Capsule endoscopy has emerged as a non-invasive alternative to traditional gastrointestinal inspection procedures, such as endoscopy and colonoscopy. Removing sedation risks, it is a patient-friendly and hospital-free procedure, which allows small bowel assessment, region not easily accessible by traditional methods. Recently, deep learning techniques have been employed to analyse capsule endoscopy images, with a focus on lesion classification and/or capsule location along the gastrointestinal tract. This research work presents a novel approach for testing the generalization capacity of deep learning techniques in the lesion location identification process using capsule endoscopy images. To achieve that, AlexNet, InceptionV3 and ResNet-152 architectures were trained exclusively in normal frames and later tested in lesion frames. Frames were sourced from KID and Kvasir-Capsule open-source datasets. Both RGB and grayscale representations were evaluated, and experiments with complete images and patches were made. Results show that the generalization capacity on lesion location of models is not so strong as their capacity for normal frame location, with colon being the most difficult organ to identify.

2025

Endpoint Detection in Breast Images for Automatic Classification of Breast Cancer Aesthetic Results

Authors
Freitas, N; Veloso, C; Mavioso, C; Cardoso, MJ; Oliveira, HP; Cardoso, JS;

Publication
ARTIFICIAL INTELLIGENCE AND IMAGING FOR DIAGNOSTIC AND TREATMENT CHALLENGES IN BREAST CARE, DEEP-BREATH 2024

Abstract
Breast cancer is the most common type of cancer in women worldwide. Because of high survival rates, there has been an increased interest in patient Quality of Life after treatment. Aesthetic results play an important role in this aspect, as these treatments can leave a mark on a patient's self-image. Despite that, there are no standard ways of assessing aesthetic outcomes. Commonly used software such as BCCT.core or BAT require the manual annotation of keypoints, which makes them time-consuming for clinical use and can lead to result variability depending on the user. Recently, there have been attempts to leverage both traditional and Deep Learning algorithms to detect keypoints automatically. In this paper, we compare several methods for the detection of Breast Endpoints across two datasets. Furthermore, we present an extended evaluation of using these models as input for full contour prediction and aesthetic evaluation using the BCCT.core software. Overall, the YOLOv9 model, fine-tuned for this task, presents the best results considering both accuracy and usability, making this architecture the best choice for this application. The main contribution of this paper is the development of a pipeline for full breast contour prediction, which reduces clinician workload and user variability for automatic aesthetic assessment.

2025

On the Energy Consumption of Rotary-Wing and Fixed-Wing UAVs in Flying Networks

Authors
Ribeiro, P; Coelho, A; Campos, R;

Publication
2025 20TH WIRELESS ON-DEMAND NETWORK SYSTEMS AND SERVICES CONFERENCE, WONS

Abstract
Unmanned Aerial Vehicles (UAVs) are increasingly employed to enable wireless communications, serving as communications nodes. In previous work, we proposed the Sustainable multi-UAV Performance-aware Placement (SUPPLY) algorithm, which focuses on the energy-efficient placement of multiple UAVs acting as Flying Access Points (FAPs). We also developed the Multi-UAV Energy Consumption (MUAVE) simulator to evaluate UAV energy consumption. However, MUAVE was designed to compute the energy consumption for rotary-wing UAVs only. In this paper, we propose eMUAVE, an enhanced version of the MUAVE simulator that enables the evaluation of the energy consumption for both rotary-wing and fixed-wing UAVs. We then use eMUAVE to evaluate the energy consumption of rotary-wing and fixed-wing UAVs in reference and random networking scenarios. The results show that rotary-wing UAVs are typically more energy-efficient than fixed-wing UAVs when following SUPPLY-defined trajectories.

2025

Machine Learning Regression-Based Prediction for Improving Performance and Energy Consumption in HPC Platforms

Authors
Coelho, M; Ocana, K; Pereira, A; Porto, A; Cardoso, DO; Lorenzon, A; Oliveira, R; Navaux, POA; Osthoff, C;

Publication
HIGH PERFORMANCE COMPUTING, CARLA 2024

Abstract
High-performance computing is pivotal for processing large datasets and executing complex simulations, ensuring faster and more accurate results. Improving the performance of software and scientific workflows in such environments requires careful analysis of their computational behavior and energy consumption. Therefore, maximizing computational throughput in these environments, through adequate software configuration and resource allocation, is essential for improving performance. The work presented in this paper focuses on leveraging regression-based machine learning and decision trees to analyze and optimize resource allocation in high-performance computing environments based on application's performance and energy metrics. Applied to a bioinformatics case study, these models enable informed decision-making by selecting the appropriate computing resources to enhance the performance of a phylogenomics software. Our contribution is to better explore and understand the efficient resource management of supercomputers, namely Santos Dumont. We show that the predictions for application's execution time using the proposed method are accurate for various amounts of computing nodes, while energy consumption predictions are less precise. The application parameters most relevant for this work are identified and the relative importance of each application parameter to the accuracy of the prediction is analysed.

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