Valderi Reis Quietinho Leithardt

Dr. Valderi Reis Quietinho Leithardt

DEETC, Instituto Superior de Engenharia de Lisboa, Instituto Politécnico de Lisboa, Lisbon, Lisboa, Portugal
orcid
Work

Research Focus & Metrics

Academic Career Length

18Years (2009-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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5 November 2022 in Sensors
Verified
Journal Article
Open access
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MFMauricio Pasetto de Freitas
Mauricio Pasetto de Freitas
VPVinícius Aquino Piai
Vinícius Aquino Piai
RFRicardo Heffel Farias
Ricardo Heffel Farias
Anita Maria da Rocha FernandesAnita Maria da Rocha Fernandes
Anita Maria da Rocha Fernandes
ARAnubis Graciela de Moraes Rossetto
Anubis Graciela de Moraes Rossetto
Valderi Reis Quietinho LeithardtValderi Reis Quietinho Leithardt
Valderi Reis Quietinho Leithardt
According to the World Health Organization, about 15% of the world’s population has some form of disability. Assistive Technology, in this context, contributes directly to the overcoming of difficulties encountered by people with disabilities in their daily lives, allowing them to receive education and become part of the labor market and society in a worthy manner. Assistive Technology has made great advances in its integration with Artificial Intelligence of Things (AIoT) devices. AIoT processes and analyzes the large amount of data generated by Internet of Things (IoT) devices and applies Artificial Intelligence models, specifically, machine learning, to discover patterns for generating insights and assisting in decision making. Based on a systematic literature review, this article aims to identify the machine-learning models used across different research on Artificial Intelligence of Things applied to Assistive Technology. The survey of the topics approached in this article also highlights the context of such research, their application, the IoT devices used, and gaps and opportunities for further development. The survey results show that 50% of the analyzed research address visual impairment, and, for this reason, most of the topics cover issues related to computational vision. Portable devices, wearables, and smartphones constitute the majority of IoT devices. Deep neural networks represent 81% of the machine-learning models applied in the reviewed research.

19 June 2023 in IEEE Access
Verified
Journal Article
Open access
Luís Augusto SilvaLuís Augusto Silva
Luís Augusto Silva
Valderi Reis Quietinho LeithardtValderi Reis Quietinho Leithardt
Valderi Reis Quietinho Leithardt
VBVivian F. López Batista
Vivian F. López Batista
Gabriel Villarrubia GonzálezGabriel Villarrubia González
Gabriel Villarrubia González
Juan Francisco De Paz SantanaJuan Francisco De Paz Santana
Juan Francisco De Paz Santana
This paper presents a novel automated road damage detection approach using Unmanned Aerial Vehicle (UAV) images and deep learning techniques. Maintaining road infrastructure is critical for ensuring a safe and sustainable transportation system. However, the manual collection of road damage data can be labor-intensive and unsafe for humans. Therefore, we propose using UAVs and Artificial Intelligence (AI) technologies to improve road damage detection’s efficiency and accuracy significantly. Our proposed approach utilizes three algorithms, YOLOv4, YOLOv5, and YOLOv7, for object detection and localization in UAV images. We trained and tested these algorithms using a combination of the RDD2022 dataset from China and a Spanish road dataset. The experimental results demonstrate that our approach is efficient and achieves 59.9% mean average precision mAP@.5 for the YOLOv5 version, 73.20% mAP@.5 for the YOLOv7 version, and 65.70% mAP@.5 for a YOLOv5 model with a Transformer Prediction Head. These results demonstrate the potential of using UAVs and deep learning for automated road damage detection and pave the way for future research in this field.

5 October 2019 in Sensors
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DSDaniel Saraiva
Daniel Saraiva
Valderi Reis Quietinho LeithardtValderi Reis Quietinho Leithardt
Valderi Reis Quietinho Leithardt
DPDiandre de Paula
Diandre de Paula
André Sales MendesAndré Sales Mendes
André Sales Mendes
Gabriel Villarrubia GonzálezGabriel Villarrubia González
Gabriel Villarrubia González
PCPaul Crocker
Paul Crocker
With the growing number of heterogeneous resource-constrained devices connected to the Internet, it becomes increasingly challenging to secure the privacy and protection of data. Strong but efficient cryptography solutions must be employed to deal with this problem, along with methods to standardize secure communications between these devices. The PRISEC module of the UbiPri middleware has this goal. In this work, we present the performance of the AES (Advanced Encryption Standard), RC6 (Rivest Cipher 6), Twofish, SPECK128, LEA, and ChaCha20-Poly1305 algorithms in Internet of Things (IoT) devices, measuring their execution times, throughput, and power consumption, with the main goal of determining which symmetric key ciphers are best to be applied in PRISEC. We verify that ChaCha20-Poly1305 is a very good option for resource constrained devices, along with the lightweight block ciphers SPECK128 and LEA.

28 April 2021 in IEEE Access
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Journal Article
Open access
Stefano Frizzo StefenonStefano Frizzo Stefenon
Stefano Frizzo Stefenon
Matheus RibeiroMatheus Ribeiro
Matheus Ribeiro
ANAdemir Nied
Ademir Nied
Viviana Cocco MarianiViviana Cocco Mariani
Viviana Cocco Mariani
Leandro dos Santos CoelhoLeandro dos Santos Coelho
Leandro dos Santos Coelho
Laio Oriel SemanLaio Oriel Seman
Laio Oriel Seman
Contaminated insulators can have higher surface conductivity, which can result in irreversible failures in the electrical power system. In this paper, the ultrasound equipment is used to assist in the prediction of failure identification in porcelain insulators of the 13.8 kV, 60 Hz pin profile. To perform the laboratory analysis, insulators from a problematic branch are removed after an inspection of the electrical system and are evaluated in the laboratory under controlled conditions. To perform the time series predictions, the stacking ensemble learning model is applied with the wavelet transform for signal filtering and noise reduction. For a complete analysis of the model, variations in its configuration were evaluated. The results of root mean square error (RMSE), mean absolute percentage error (MAPE), mean absolute error (MAE), and coefficient of determination (R 2 ) are presented. To validate the result, a benchmarking is presented with well-established models, such as an adaptive neuro-fuzzy inference system (ANFIS) and long-term short-term memory (LSTM).

16 August 2022 in Sensors
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NNNemesio Fava Sopelsa Neto
Nemesio Fava Sopelsa Neto
Stefano Frizzo StefenonStefano Frizzo Stefenon
Stefano Frizzo Stefenon
LMLuiz Henrique Meyer
Luiz Henrique Meyer
RORaúl García Ovejero
Raúl García Ovejero
Valderi Reis Quietinho LeithardtValderi Reis Quietinho Leithardt
Valderi Reis Quietinho Leithardt
To improve the monitoring of the electrical power grid, it is necessary to evaluate the influence of contamination in relation to leakage current and its progression to a disruptive discharge. In this paper, insulators were tested in a saline chamber to simulate the increase of salt contamination on their surface. From the time series forecasting of the leakage current, it is possible to evaluate the development of the fault before a flashover occurs. In this paper, for a complete evaluation, the long short-term memory (LSTM), group method of data handling (GMDH), adaptive neuro-fuzzy inference system (ANFIS), bootstrap aggregation (bagging), sequential learning (boosting), random subspace, and stacked generalization (stacking) ensemble learning models are analyzed. From the results of the best structure of the models, the hyperparameters are evaluated and the wavelet transform is used to obtain an enhanced model. The contribution of this paper is related to the improvement of well-established models using the wavelet transform, thus obtaining hybrid models that can be used for several applications. The results showed that using the wavelet transform leads to an improvement in all the used models, especially the wavelet ANFIS model, which had a mean RMSE of 1.58 ×10−3, being the model that had the best result. Furthermore, the results for the standard deviation were 2.18 ×10−19, showing that the model is stable and robust for the application under study. Future work can be performed using other components of the distribution power grid susceptible to contamination because they are installed outdoors.

30 October 2022 in Sensors
Verified
Journal Article
Open access
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NBNathielle Waldrigues Branco
Nathielle Waldrigues Branco
MCMariana Santos Matos Cavalca
Mariana Santos Matos Cavalca
Stefano Frizzo StefenonStefano Frizzo Stefenon
Stefano Frizzo Stefenon
Valderi Reis Quietinho LeithardtValderi Reis Quietinho Leithardt
Valderi Reis Quietinho Leithardt
An electric power distribution utility is responsible for providing energy to consumers in a continuous and stable way. Failures in the electrical power system reduce the reliability indexes of the grid, directly harming its performance. For this reason, there is a need for failure prediction to reestablish power in the shortest possible time. Considering an evaluation of the number of failures over time, this paper proposes performing failure prediction during the first year of the pandemic in Brazil (2020) to verify the feasibility of using time series forecasting models for fault prediction. The long short-term memory (LSTM) model will be evaluated to obtain a forecast result that an electric power utility can use to organize maintenance teams. The wavelet transform has shown itself to be promising in improving the predictive ability of LSTM, making the wavelet LSTM model suitable for the study at hand. The assessments show that the proposed approach has better results regarding the error in prediction and has robustness when statistical analysis is performed.