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Valderi R. Q. Leithardt is a full-time adjunct professor with exclusive dedication and an integrated member of VALORIZA - Research Center for the Valorization of Endogenous Resources, Polytechnic Institute of Portalegre, Portugal. He has experience in computer science, with an emphasis on distributed systems, working mainly on the following topics: Internet of Things, cloud computing, communication protocols and data privacy.
The use of information communication technologies (ICT) in education brings up new possibilities of promoting learning and health experiences. In this sense, education contexts of the 21st century must consider these two areas of knowledge, especially their integration. This article presents learning practices developed with mobile devices and games in order to improve learning and well-being in children and adolescents undergoing cancer treatment in a non-formal educational setting. The methodology is based on qualitative case studies with content-based data analyses, involving informal interviews and observation methods. The study considers data from five patients who participated in the research between 2015 and 2019. The results demonstrate a positive influence of the practices with mobile technologies and games in terms of learning and in the well-being experience of patients during the treatment.
Paulo Ricardo dos Santos; Débora N. F. Barbosa; Eduardo G. Azevedo Neto; Jorge L. V. Barbosa; Sérgio D. Correia; Valderi R. Q. Leithardt. Learning and Well-Being in Educational Practices with Children and Adolescents Undergoing Cancer Treatment. Education Sciences 2021, 11, 442 .
AMA StylePaulo Ricardo dos Santos, Débora N. F. Barbosa, Eduardo G. Azevedo Neto, Jorge L. V. Barbosa, Sérgio D. Correia, Valderi R. Q. Leithardt. Learning and Well-Being in Educational Practices with Children and Adolescents Undergoing Cancer Treatment. Education Sciences. 2021; 11 (8):442.
Chicago/Turabian StylePaulo Ricardo dos Santos; Débora N. F. Barbosa; Eduardo G. Azevedo Neto; Jorge L. V. Barbosa; Sérgio D. Correia; Valderi R. Q. Leithardt. 2021. "Learning and Well-Being in Educational Practices with Children and Adolescents Undergoing Cancer Treatment." Education Sciences 11, no. 8: 442.
The increase in irrigated crop areas, especially in countries such as Spain and Italy, has led to an increase in technological solutions for monitoring the irrigation. Furthermore, the centre pivot irrigation systems used in these crops have facilitated the daily work of farmers in recent years, however, the monitoring of these systems and the reporting of problems in their operation has become a key aspect during the growing season. For this reason, different monitoring solutions have been proposed from the area of Precision Agriculture and Information and Communication Technologies (ICTs). Nevertheless, it is necessary that these solutions take into account the digital divide their potential users may suffer and be low-cost solutions in order to be attractive to the end-users. This paper presents several low-cost solutions using novel user interfaces and wireless communication technologies for the monitoring of this type of irrigation systems. This paper presents the results obtained after the deployment of the proposed systems on a real environment and the main conclusions drawn after their use in irrigated maize crops.
Diego Mateos Matilla; Álvaro Lozano Murciego; Diego M. Jiménez-Bravo; André Sales Mendes; Valderi R.Q. Leithardt. Low-cost Edge Computing devices and novel user interfaces for monitoring pivot irrigation systems based on Internet of Things and LoRaWAN technologies. Biosystems Engineering 2021, 1 .
AMA StyleDiego Mateos Matilla, Álvaro Lozano Murciego, Diego M. Jiménez-Bravo, André Sales Mendes, Valderi R.Q. Leithardt. Low-cost Edge Computing devices and novel user interfaces for monitoring pivot irrigation systems based on Internet of Things and LoRaWAN technologies. Biosystems Engineering. 2021; ():1.
Chicago/Turabian StyleDiego Mateos Matilla; Álvaro Lozano Murciego; Diego M. Jiménez-Bravo; André Sales Mendes; Valderi R.Q. Leithardt. 2021. "Low-cost Edge Computing devices and novel user interfaces for monitoring pivot irrigation systems based on Internet of Things and LoRaWAN technologies." Biosystems Engineering , no. : 1.
Language learners often face communication problems when they need to express themselves and do not have the ability to do so. On the other hand, continuous advances in technology are creating new opportunities to improve second language (L2) acquisition through context-aware ubiquitous learning (CAUL) technology. Since vocabulary is the foundation of all language acquisition, this article presents ULearnEnglish, an open-source system to allow ubiquitous English learning focused on incidental vocabulary acquisition. To evaluate our proposal, 15 learners used the developed system, and 10 answered a survey based on the Technology Acceptance Model (TAM). Results indicate a favorable response to the application of incidental learning techniques in combination with the learner context. ULearnEnglish achieved an acceptance rate of 78.66% for the perception of utility, 96% for the perception of ease of use, 86.5% for user context assessment, and 88% for ubiquity. Among its main contributions, this study demonstrates a possible tool for ubiquitous use in the future in language learning; additionally, further studies can use the available resources to develop the system.
Letícia da Silva; Eduardo Neto; Rosemary Francisco; Jorge Barbosa; Luis Silva; Valderi Leithardt. ULearnEnglish: An Open Ubiquitous System for Assisting in Learning English Vocabulary. Electronics 2021, 10, 1692 .
AMA StyleLetícia da Silva, Eduardo Neto, Rosemary Francisco, Jorge Barbosa, Luis Silva, Valderi Leithardt. ULearnEnglish: An Open Ubiquitous System for Assisting in Learning English Vocabulary. Electronics. 2021; 10 (14):1692.
Chicago/Turabian StyleLetícia da Silva; Eduardo Neto; Rosemary Francisco; Jorge Barbosa; Luis Silva; Valderi Leithardt. 2021. "ULearnEnglish: An Open Ubiquitous System for Assisting in Learning English Vocabulary." Electronics 10, no. 14: 1692.
Lidia M. da Silva; Lucas P. S. Dias; Jorge L. V. Barbosa; Sandro J. Rigo; Julio C. S. dos Anjos; Claudio F. R. Geyer; Valderi R. Q. Leithardt. Learning analytics and collaborative groups of learners in distance education: a systematic mapping study. Informatics in Education 2021, 1 .
AMA StyleLidia M. da Silva, Lucas P. S. Dias, Jorge L. V. Barbosa, Sandro J. Rigo, Julio C. S. dos Anjos, Claudio F. R. Geyer, Valderi R. Q. Leithardt. Learning analytics and collaborative groups of learners in distance education: a systematic mapping study. Informatics in Education. 2021; ():1.
Chicago/Turabian StyleLidia M. da Silva; Lucas P. S. Dias; Jorge L. V. Barbosa; Sandro J. Rigo; Julio C. S. dos Anjos; Claudio F. R. Geyer; Valderi R. Q. Leithardt. 2021. "Learning analytics and collaborative groups of learners in distance education: a systematic mapping study." Informatics in Education , no. : 1.
The present work proposed a low-cost portable device as an enabling technology for agriculture using multispectral imaging and machine learning in soil texture. Clay is an important factor for the verification and monitoring of soil use due to its fast reaction to chemical and surface changes. The system developed uses the analysis of reflectance in wavebands for clay prediction. The selection of each wavelength is performed through an LED lamp panel. A NoIR microcamera controlled by a Raspberry Pi device is employed to acquire the image and unfold it in RGB histograms. Results showed a good prediction performance with R2 of 0.96, RMSEC of 3.66% and RMSECV of 16.87%. The high portability allows the equipment to be used in a field providing strategic information related to soil sciences.
Gilson Helfer; Jorge Barbosa; Douglas Alves; Adilson da Costa; Marko Beko; Valderi Leithardt. Multispectral Cameras and Machine Learning Integrated into Portable Devices as Clay Prediction Technology. Journal of Sensor and Actuator Networks 2021, 10, 40 .
AMA StyleGilson Helfer, Jorge Barbosa, Douglas Alves, Adilson da Costa, Marko Beko, Valderi Leithardt. Multispectral Cameras and Machine Learning Integrated into Portable Devices as Clay Prediction Technology. Journal of Sensor and Actuator Networks. 2021; 10 (3):40.
Chicago/Turabian StyleGilson Helfer; Jorge Barbosa; Douglas Alves; Adilson da Costa; Marko Beko; Valderi Leithardt. 2021. "Multispectral Cameras and Machine Learning Integrated into Portable Devices as Clay Prediction Technology." Journal of Sensor and Actuator Networks 10, no. 3: 40.
New Internet of Things (IoT) applications are enabling the development of projects that help with monitoring people with different diseases in their daily lives. Alzheimer’s is a disease that affects neurological functions and needs support to maintain maximum independence and security of patients during this stage of life, as the cure and reversal of symptoms have not yet been discovered. The IoT-based monitoring system provides the caregivers’ support in monitoring people with Alzheimer’s disease (AD). This paper presents an ontology-based computational model that receives physiological data from external IoT applications, allowing identification of potentially dangerous behaviors for patients with AD. The main scientific contribution of this work is the specification of a model focusing on Alzheimer’s disease using the analysis of context histories and context prediction, which, considering the state of the art, is the only one that uses analysis of context histories to perform predictions. In this research, we also propose a simulator to generate activities of the daily life of patients, allowing the creation of data sets. These data sets were used to evaluate the contributions of the model and were generated according to the standardization of the ontology. The simulator generated 1026 scenarios applied to guide the predictions, which achieved average accurary of 97.44%. The experiments also allowed the learning of 20 relevant lessons on technological, medical, and methodological aspects that are recorded in this article.
Savanna Machado; João Tavares; Márcio Martins; Jorge Barbosa; Gabriel González; Valderi Leithardt. Ambient Intelligence Based on IoT for Assisting People with Alzheimer’s Disease Through Context Histories. Electronics 2021, 10, 1260 .
AMA StyleSavanna Machado, João Tavares, Márcio Martins, Jorge Barbosa, Gabriel González, Valderi Leithardt. Ambient Intelligence Based on IoT for Assisting People with Alzheimer’s Disease Through Context Histories. Electronics. 2021; 10 (11):1260.
Chicago/Turabian StyleSavanna Machado; João Tavares; Márcio Martins; Jorge Barbosa; Gabriel González; Valderi Leithardt. 2021. "Ambient Intelligence Based on IoT for Assisting People with Alzheimer’s Disease Through Context Histories." Electronics 10, no. 11: 1260.
Currently, there are more than 1.55 million cases of SARS-CoV-2 infection in Spain. Of these, it is estimated that around 45% will present respiratory complications, which represents approximately 620,000 patients who will need respiratory rehabilitation. The health system has no resources for this huge quantity of patients after the hospital discharge to finish the complete recovery and avoid the chronicity of the symptoms. We propose an application named RespiraConNosotros. The application has been created and designed to guide users in performing respiratory rehabilitation exercises, especially for COVID-19 patients, and it also facilitates patient–physiotherapist contact via chat or video calling to help patients. It is accessible for all users and on all devices. All exercises would be guided and supervised by a specialized physiotherapist who suggests, adapts, and guides the exercise according to the function level of each patient. Data obtained was satisfactory; all patients pointed out the easy access, the intuitive format, and the advantage of communicating with an expert. Concerning functional assessment, all participants improved their score on the Borg scale after performing the intervention with the application.This platform would help respiratory patients to make rehabilitation treatments to recover their pulmonary function and to decrease or eliminate the possible complications they have. It never substitutes any prescribed treatment. In conclusion, RespiraConNosotros is a simple, viable, and safe alternative for the improvement and maintenance of respiratory capacity and patient’s functionality affected by COVID-19. It could be used as a complement to face-to-face treatment when the situation allows it.
Beatriz Bermejo-Gil; Fátima Pérez-Robledo; Rocío Llamas-Ramos; Luís Silva; André Sales-Mendes; Valderi Leithardt; Inés Llamas-Ramos. RespiraConNosotros: A Viable Home-Based Telerehabilitation System for Respiratory Patients. Sensors 2021, 21, 3318 .
AMA StyleBeatriz Bermejo-Gil, Fátima Pérez-Robledo, Rocío Llamas-Ramos, Luís Silva, André Sales-Mendes, Valderi Leithardt, Inés Llamas-Ramos. RespiraConNosotros: A Viable Home-Based Telerehabilitation System for Respiratory Patients. Sensors. 2021; 21 (10):3318.
Chicago/Turabian StyleBeatriz Bermejo-Gil; Fátima Pérez-Robledo; Rocío Llamas-Ramos; Luís Silva; André Sales-Mendes; Valderi Leithardt; Inés Llamas-Ramos. 2021. "RespiraConNosotros: A Viable Home-Based Telerehabilitation System for Respiratory Patients." Sensors 21, no. 10: 3318.
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).
Stefano Frizzo Stefenon; Matheus Henrique Dal Molin Ribeiro; Ademir Nied; Viviana Cocco Mariani; Leandro Dos Santos Coelho; Valderi Reis Quietinho Leithardt; Luis Augusto Silva; Laio Oriel Seman. Hybrid Wavelet Stacking Ensemble Model for Insulators Contamination Forecasting. IEEE Access 2021, 9, 66387 -66397.
AMA StyleStefano Frizzo Stefenon, Matheus Henrique Dal Molin Ribeiro, Ademir Nied, Viviana Cocco Mariani, Leandro Dos Santos Coelho, Valderi Reis Quietinho Leithardt, Luis Augusto Silva, Laio Oriel Seman. Hybrid Wavelet Stacking Ensemble Model for Insulators Contamination Forecasting. IEEE Access. 2021; 9 ():66387-66397.
Chicago/Turabian StyleStefano Frizzo Stefenon; Matheus Henrique Dal Molin Ribeiro; Ademir Nied; Viviana Cocco Mariani; Leandro Dos Santos Coelho; Valderi Reis Quietinho Leithardt; Luis Augusto Silva; Laio Oriel Seman. 2021. "Hybrid Wavelet Stacking Ensemble Model for Insulators Contamination Forecasting." IEEE Access 9, no. : 66387-66397.
Advances in communication technologies have made the interaction of small devices, such as smartphones, wearables, and sensors, scattered on the Internet, bringing a whole new set of complex applications with ever greater task processing needs. These Internet of things (IoT) devices run on batteries with strict energy restrictions. They tend to offload task processing to remote servers, usually to cloud computing (CC) in datacenters geographically located away from the IoT device. In such a context, this work proposes a dynamic cost model to minimize energy consumption and task processing time for IoT scenarios in mobile edge computing environments. Our approach allows for a detailed cost model, with an algorithm called TEMS that considers energy, time consumed during processing, the cost of data transmission, and energy in idle devices. The task scheduling chooses among cloud or mobile edge computing (MEC) server or local IoT devices to achieve better execution time with lower cost. The simulated environment evaluation saved up to 51.6% energy consumption and improved task completion time up to 86.6%.
Julio dos Anjos; João Gross; Kassiano Matteussi; Gabriel González; Valderi Leithardt; Claudio Geyer. An Algorithm to Minimize Energy Consumption and Elapsed Time for IoT Workloads in a Hybrid Architecture. Sensors 2021, 21, 2914 .
AMA StyleJulio dos Anjos, João Gross, Kassiano Matteussi, Gabriel González, Valderi Leithardt, Claudio Geyer. An Algorithm to Minimize Energy Consumption and Elapsed Time for IoT Workloads in a Hybrid Architecture. Sensors. 2021; 21 (9):2914.
Chicago/Turabian StyleJulio dos Anjos; João Gross; Kassiano Matteussi; Gabriel González; Valderi Leithardt; Claudio Geyer. 2021. "An Algorithm to Minimize Energy Consumption and Elapsed Time for IoT Workloads in a Hybrid Architecture." Sensors 21, no. 9: 2914.
Although the skin effect has been widely studied over the years, many of its topics remain unclear for most electrical engineers, including undergraduate students and fresh graduates. Yet, in the cases of application of power frequency current, the knowledge gap to be bridged is more significant. Thus, for contributing to the widening in the knowledge of this effect, this work presents an analysis of the behavior of the current density distribution over the cross-section of differently combined rectangular conductors subject to power frequency current. In this case, since an analytical approach is not feasible, the numerical method of matrix solution of integral equations was adopted due to its simplicity and fast convergence and its application is presented through some providentially chosen theoretical examples before a practical case may be analyzed. As the main results, the influence of a correlated effect that is the proximity effect shows itself as being predominant and the method presents itself as being very convenient for studying the current density distribution in conductors with a cross-section other than the circular, which allow bridging the knowledge gap in this theme. Moreover, the comparison of theoretical cases quite significant. Moreover, the method is adequate to planar configurations, by typical configurations, as in the case of bus bars of electrical panels.
Sergio H. L. Cabral; Savio L. Bertoli; Alessandro Medeiros; Crisleine Regina Hillesheim; Carolina K. De Souza; Stefano Frizzo Stefenon; Ademir Nied; Valderi Reis Quietinho Leithardt; Gabriel Villarrubia Gonzalez. Practical Aspects of the Skin Effect in Low Frequencies in Rectangular Conductors. IEEE Access 2021, 9, 49424 -49433.
AMA StyleSergio H. L. Cabral, Savio L. Bertoli, Alessandro Medeiros, Crisleine Regina Hillesheim, Carolina K. De Souza, Stefano Frizzo Stefenon, Ademir Nied, Valderi Reis Quietinho Leithardt, Gabriel Villarrubia Gonzalez. Practical Aspects of the Skin Effect in Low Frequencies in Rectangular Conductors. IEEE Access. 2021; 9 (99):49424-49433.
Chicago/Turabian StyleSergio H. L. Cabral; Savio L. Bertoli; Alessandro Medeiros; Crisleine Regina Hillesheim; Carolina K. De Souza; Stefano Frizzo Stefenon; Ademir Nied; Valderi Reis Quietinho Leithardt; Gabriel Villarrubia Gonzalez. 2021. "Practical Aspects of the Skin Effect in Low Frequencies in Rectangular Conductors." IEEE Access 9, no. 99: 49424-49433.
The usage of drones is increasingly spreading into new fields of application, ranging from agriculture to security. One of these new applications is sound recording in areas of difficult access. The challenge that arises when using drones for this purpose is that the sound of the recorded sources must be separated from the noise produced by the drone. The intensity of the noise emitted by the drone depends on several factors such as engine power, propeller rotation speed, or propeller type. Noise reduction is thus one of the greatest challenges for the next generations of unmanned aerial vehicles (UAVs) and unmanned aerial systems (UAS). Even though some advances have been made on that matter, drones still produce a considerable noise. In this article, we approach the problem of removing drone noise from single-channel audio recordings using blind source separation (BSS) techniques, and in particular, the singular spectrum analysis algorithm (SSA). Furthermore, we propose an optimization of this algorithm with a spatial complexity of
Francisco Garcia Encinas; Luis Augusto Silva; Andre Sales Mendes; Gabriel Villarrubia Gonzalez; Valderi Reis Quietinho Leithardt; Juan Francisco De Paz Santana. Singular Spectrum Analysis for Source Separation in Drone-Based Audio Recording. IEEE Access 2021, 9, 43444 -43457.
AMA StyleFrancisco Garcia Encinas, Luis Augusto Silva, Andre Sales Mendes, Gabriel Villarrubia Gonzalez, Valderi Reis Quietinho Leithardt, Juan Francisco De Paz Santana. Singular Spectrum Analysis for Source Separation in Drone-Based Audio Recording. IEEE Access. 2021; 9 ():43444-43457.
Chicago/Turabian StyleFrancisco Garcia Encinas; Luis Augusto Silva; Andre Sales Mendes; Gabriel Villarrubia Gonzalez; Valderi Reis Quietinho Leithardt; Juan Francisco De Paz Santana. 2021. "Singular Spectrum Analysis for Source Separation in Drone-Based Audio Recording." IEEE Access 9, no. : 43444-43457.
Although this is a fact that is not very explored in the literature, there are two possible forms to connect the stator winding of an induction motor in the delta. The choice for one of these forms defines the amplitude of the stator transient current during the switching from star to delta connection when the motor is driven by a star-delta starting system, which is the most widely used and diffused method for starting an induction motor. One of the possible forms of the delta connection gives rise to a switching current with a relatively small amplitude, which gives it the denomination of preferential. The other form has a relatively higher amplitude of switching current, but it is the most recommended and indicated in diagrams of catalogues and motor plates. Therefore, it is here called “common”. With the aim of evidencing how the differences between these two forms of delta connection are manifested, this paper approaches the issue experimentally, through a methodology with statistical support, for a better characterization of the performance of each of these forms of delta connection, in the case of the widely popular star-delta starting method.
José Itajiba; Cézar Varnier; Sergio Cabral; Stéfano Stefenon; Valderi Leithardt; Raúl Ovejero; Ademir Nied; Kin-Choong Yow. Experimental Comparison of Preferential vs. Common Delta Connections for the Star-Delta Starting of Induction Motors. Energies 2021, 14, 1318 .
AMA StyleJosé Itajiba, Cézar Varnier, Sergio Cabral, Stéfano Stefenon, Valderi Leithardt, Raúl Ovejero, Ademir Nied, Kin-Choong Yow. Experimental Comparison of Preferential vs. Common Delta Connections for the Star-Delta Starting of Induction Motors. Energies. 2021; 14 (5):1318.
Chicago/Turabian StyleJosé Itajiba; Cézar Varnier; Sergio Cabral; Stéfano Stefenon; Valderi Leithardt; Raúl Ovejero; Ademir Nied; Kin-Choong Yow. 2021. "Experimental Comparison of Preferential vs. Common Delta Connections for the Star-Delta Starting of Induction Motors." Energies 14, no. 5: 1318.
The application of ubiquitous computing has increased in recent years, especially due to the development of technologies such as mobile computing, more accurate sensors, and specific protocols for the Internet of Things (IoT). One of the trends in this area of research is the use of context awareness. In agriculture, the context involves the environment, for example, the conditions found inside a greenhouse. Recently, a series of studies have proposed the use of sensors to monitor production and/or the use of cameras to obtain information about cultivation, providing data, reminders, and alerts to farmers. This article proposes a computational model for indoor agriculture called IndoorPlant. The model uses the analysis of context histories to provide intelligent generic services, such as predicting productivity, indicating problems that cultivation may suffer, and giving suggestions for improvements in greenhouse parameters. IndoorPlant was tested in three scenarios of the daily life of farmers with hydroponic production data that were obtained during seven months of cultivation of radicchio, lettuce, and arugula. Finally, the article presents the results obtained through intelligent services that use context histories. The scenarios used services to recommend improvements in cultivation, profiles and, finally, prediction of the cultivation time of radicchio, lettuce, and arugula using the partial least squares (PLS) regression technique. The prediction results were relevant since the following values were obtained: 0.96 (R2, coefficient of determination), 1.06 (RMSEC, square root of the mean square error of calibration), and 1.94 (RMSECV, square root of the mean square error of cross validation) for radicchio; 0.95 (R2), 1.37 (RMSEC), and 3.31 (RMSECV) for lettuce; 0.93 (R2), 1.10 (RMSEC), and 1.89 (RMSECV) for arugula. Eight farmers with different functions on the farm filled out a survey based on the technology acceptance model (TAM). The results showed 92% acceptance regarding utility and 98% acceptance for ease of use.
Bruno Martini; Gilson Helfer; Jorge Barbosa; Regina Espinosa Modolo; Marcio da Silva; Rodrigo de Figueiredo; André Mendes; Luís Silva; Valderi Leithardt. IndoorPlant: A Model for Intelligent Services in Indoor Agriculture Based on Context Histories. Sensors 2021, 21, 1631 .
AMA StyleBruno Martini, Gilson Helfer, Jorge Barbosa, Regina Espinosa Modolo, Marcio da Silva, Rodrigo de Figueiredo, André Mendes, Luís Silva, Valderi Leithardt. IndoorPlant: A Model for Intelligent Services in Indoor Agriculture Based on Context Histories. Sensors. 2021; 21 (5):1631.
Chicago/Turabian StyleBruno Martini; Gilson Helfer; Jorge Barbosa; Regina Espinosa Modolo; Marcio da Silva; Rodrigo de Figueiredo; André Mendes; Luís Silva; Valderi Leithardt. 2021. "IndoorPlant: A Model for Intelligent Services in Indoor Agriculture Based on Context Histories." Sensors 21, no. 5: 1631.
Interruptions in the supply of electricity cause numerous losses to consumers, whether residential or industrial and may result in fines being imposed on the regulatory agency’s concessionaire. In Brazil, the electrical transmission and distribution systems cover a large territorial area, and because they are usually outdoors, they are exposed to environmental variations. In this context, periodic inspections are carried out on the electrical networks, and ultrasound equipment is widely used, due to non-destructive analysis characteristics. Ultrasonic inspection allows the identification of defective insulators based on the signal interpreted by an operator. This task fundamentally depends on the operator’s experience in this interpretation. In this way, it is intended to test machine learning applications to interpret ultrasound signals obtained from electrical grid insulators, distribution, class 25 kV. Currently, research in the area uses several models of artificial intelligence for various types of evaluation. This paper studies Multilayer Perceptron networks’ application to the classification of the different conditions of ceramic insulators based on a restricted database of ultrasonic signals recorded in the laboratory.
Nemesio Sopelsa Neto; Stéfano Stefenon; Luiz Meyer; Rafael Bruns; Ademir Nied; Laio Seman; Gabriel Gonzalez; Valderi Leithardt; Kin-Choong Yow. A Study of Multilayer Perceptron Networks Applied to Classification of Ceramic Insulators Using Ultrasound. Applied Sciences 2021, 11, 1592 .
AMA StyleNemesio Sopelsa Neto, Stéfano Stefenon, Luiz Meyer, Rafael Bruns, Ademir Nied, Laio Seman, Gabriel Gonzalez, Valderi Leithardt, Kin-Choong Yow. A Study of Multilayer Perceptron Networks Applied to Classification of Ceramic Insulators Using Ultrasound. Applied Sciences. 2021; 11 (4):1592.
Chicago/Turabian StyleNemesio Sopelsa Neto; Stéfano Stefenon; Luiz Meyer; Rafael Bruns; Ademir Nied; Laio Seman; Gabriel Gonzalez; Valderi Leithardt; Kin-Choong Yow. 2021. "A Study of Multilayer Perceptron Networks Applied to Classification of Ceramic Insulators Using Ultrasound." Applied Sciences 11, no. 4: 1592.
This work presents an integrated thermal-electrical simulation model, capable of taking into account the thermal and electrical effects of the battery and photovoltaic panels for each instant of time in a given orbit and attitude. Using the physical equations that govern the thermal and electrical models involved during a CubeSat operation, the proposed integrated model can estimate the temperature and energy conditions of the battery, not only in an isolated way but also in considering the mutual effects on the system. Besides, special attention is given to photovoltaic panels used in the energy harvesting process, whose performance is affected by irradiance and temperature along the orbit. The integrated model can be useful for engineers when developing the subsystems of their CubeSats, taking into account, for example, the battery temperature control through a heater. Simulations were performed to illustrate the functioning of the proposed model with variations in the power requirements of its modules and the temperature of the battery throughout the orbit, and a heater’s influence on it.
Sara Vega Martinez; Edemar Filho; Laio Seman; Eduardo Bezerra; Vicente Nicolau; Raúl Ovejero; Valderi Leithardt. An Integrated Thermal-Electrical Model for Simulations of Battery Behavior in CubeSats. Applied Sciences 2021, 11, 1554 .
AMA StyleSara Vega Martinez, Edemar Filho, Laio Seman, Eduardo Bezerra, Vicente Nicolau, Raúl Ovejero, Valderi Leithardt. An Integrated Thermal-Electrical Model for Simulations of Battery Behavior in CubeSats. Applied Sciences. 2021; 11 (4):1554.
Chicago/Turabian StyleSara Vega Martinez; Edemar Filho; Laio Seman; Eduardo Bezerra; Vicente Nicolau; Raúl Ovejero; Valderi Leithardt. 2021. "An Integrated Thermal-Electrical Model for Simulations of Battery Behavior in CubeSats." Applied Sciences 11, no. 4: 1554.
Developing star trackers quickly is non-trivial. Achieving reproducible results and comparing different algorithms are also open problems. In this sense, this work proposes the use of synthetic star images (a simulated sky), allied with the standardized structure of the Universal Verification Methodology as the base of a design approach. The aim is to organize the project, speed up the development time by providing a standard verification methodology. Future rework is reduced through two methods: a verification platform that us shared under a free software licence; and the layout of Universal Verification Methodology enforces reusability of code through an object-oriented approach. We propose a black-box structure for the verification platform with standard interfaces, and provide examples showing how this approach can be applied to the development of a star tracker for small satellites, targeting a system-on-a-chip design. The same test benches were applied to both early conceptual software-only implementations, and later optimized software-hardware hybrid systems, in a hardware-in-the-loop configuration. This test bench reuse strategy was interesting also to show the regression test capability of the developed platform. Furthermore, the simulator was used to inject specific noise, in order to evaluate the system under some real-world conditions.
Victor Schulz; Gabriel Marcelino; Laio Seman; Jeferson Barros; Sangkyun Kim; Mengu Cho; Gabriel González; Valderi Leithardt; Eduardo Bezerra. Universal Verification Platform and Star Simulator for Fast Star Tracker Design. Sensors 2021, 21, 907 .
AMA StyleVictor Schulz, Gabriel Marcelino, Laio Seman, Jeferson Barros, Sangkyun Kim, Mengu Cho, Gabriel González, Valderi Leithardt, Eduardo Bezerra. Universal Verification Platform and Star Simulator for Fast Star Tracker Design. Sensors. 2021; 21 (3):907.
Chicago/Turabian StyleVictor Schulz; Gabriel Marcelino; Laio Seman; Jeferson Barros; Sangkyun Kim; Mengu Cho; Gabriel González; Valderi Leithardt; Eduardo Bezerra. 2021. "Universal Verification Platform and Star Simulator for Fast Star Tracker Design." Sensors 21, no. 3: 907.
Since the early 2000s, life in cities has changed significantly due to the Internet of Things (IoT). This concept enables developers to integrate different devices collecting, storing, and processing a large amount of data, enabling new services to improve various professional and personal activities. However, privacy issues arise with a large amount of data generated, and solutions based on blockchain technology and smart contract have been developed to address these issues. Nevertheless, several issues must still be taken into account when developing blockchain architectures aimed at the IoT scenario because security flaws still exist in smart contracts, mainly due to the lack of ease when building the code. This article presents a blockchain storage architecture focused on license plate recognition (LPR) systems for smart cities focusing on privacy, performance, and security. The proposed architecture relies on the Ethereum platform. Each smart contract matches the privacy preferences of a license plate to be anonymized through public encryption. The storage of data captured by the LPR system can only be done if the smart contract enables it. However, in the case of motivation foreseen by the legislation, a competent user can change the smart contract and enable the storage of the data captured by the LPR system. Experimental results show that the performance of the proposed architecture is satisfactory, regarding the scalability of the built private network. Furthermore, tests on our smart contract using security and structure analysis tools on the developed script demonstrate that our solution is fraud-proof. The results obtained in all experiments bring evidence that our architecture is feasible to be used in real scenarios.
Iago Sestrem Ochôa; Valderi Reis Quietinho Leithardt; Leonardo Calbusch; Juan De Paz Santana; Wemerson Delcio Parreira; Laio Oriel Seman; Cesar Zeferino. Performance and Security Evaluation on a Blockchain Architecture for License Plate Recognition Systems. Applied Sciences 2021, 11, 1255 .
AMA StyleIago Sestrem Ochôa, Valderi Reis Quietinho Leithardt, Leonardo Calbusch, Juan De Paz Santana, Wemerson Delcio Parreira, Laio Oriel Seman, Cesar Zeferino. Performance and Security Evaluation on a Blockchain Architecture for License Plate Recognition Systems. Applied Sciences. 2021; 11 (3):1255.
Chicago/Turabian StyleIago Sestrem Ochôa; Valderi Reis Quietinho Leithardt; Leonardo Calbusch; Juan De Paz Santana; Wemerson Delcio Parreira; Laio Oriel Seman; Cesar Zeferino. 2021. "Performance and Security Evaluation on a Blockchain Architecture for License Plate Recognition Systems." Applied Sciences 11, no. 3: 1255.
Cryptography is considered indispensable among security measures applied to data concerning insecure means of transmission. Among various existent algorithms on asymmetric cryptography, we may cite Elliptic Curve Cryptography (ECC), which has been widely used due to its security level and reduced key sizes. When compared to Rivest, Shamir and Adleman (RSA), for example, ECC can maintain security levels with a shorter key. Elliptic Curve Point Multiplication (ECPM) is the main function in ECC, and is the component with the highest hardware cost. Lots of ECPM implementations have been applied on hardware targeting the acceleration of its calculus. This article presents a systematic review of literature on ECPM implementations on both Field-Programmable Gate Array (FPGA) and Application-Specific Integrated Circuit (ASIC). The obtained results show which methods and technologies have been used to implement ECPM on hardware and present some findings of the choices available to the hardware designers.
Arielle Verri Lucca; Guilherme Mariano Sborz; Valderi Leithardt; Marko Beko; Cesar Albenes Zeferino; Wemerson Parreira. A Review of Techniques for Implementing Elliptic Curve Point Multiplication on Hardware. Journal of Sensor and Actuator Networks 2020, 10, 3 .
AMA StyleArielle Verri Lucca, Guilherme Mariano Sborz, Valderi Leithardt, Marko Beko, Cesar Albenes Zeferino, Wemerson Parreira. A Review of Techniques for Implementing Elliptic Curve Point Multiplication on Hardware. Journal of Sensor and Actuator Networks. 2020; 10 (1):3.
Chicago/Turabian StyleArielle Verri Lucca; Guilherme Mariano Sborz; Valderi Leithardt; Marko Beko; Cesar Albenes Zeferino; Wemerson Parreira. 2020. "A Review of Techniques for Implementing Elliptic Curve Point Multiplication on Hardware." Journal of Sensor and Actuator Networks 10, no. 1: 3.
During satellite development, engineers need to simulate and understand the satellite’s behavior in orbit and minimize failures or inadequate satellite operation. In this sense, one crucial assessment is the irradiance field, which impacts, for example, the power generation through the photovoltaic cells, as well as rules the satellite’s thermal conditions. This good practice is also valid for CubeSat projects. This paper presents a numerical tool to explore typical irradiation scenarios for CubeSat missions by combining state-of-the-art models. Such a tool can provide the input estimation for software and hardware in the loop analysis for a given initial condition and predict it along with the satellite’s lifespan. Three main models will be considered to estimate the irradiation flux over a CubeSat, namely an orbit, an attitude, and a radiation source model, including solar, albedo, and infrared emitted by the Earth. A case study illustrating the tool’s abilities is presented for a typical CubeSats’ two-line element set (TLE) and five attitudes. Finally, a possible application of the tool as an input to a CubeSat task-scheduling is introduced. The results show that the complete model’s use has considerable differences from the simplified models sometimes used in the literature.
Edemar Morsch Filho; Laio Oriel Seman; Cezar Antônio Rigo; Vicente De Paulo Nicolau; Raúl García Ovejero; Valderi Reis Quietinho Leithardt. Irradiation Flux Modelling for Thermal–Electrical Simulation of CubeSats: Orbit, Attitude and Radiation Integration. Energies 2020, 13, 6691 .
AMA StyleEdemar Morsch Filho, Laio Oriel Seman, Cezar Antônio Rigo, Vicente De Paulo Nicolau, Raúl García Ovejero, Valderi Reis Quietinho Leithardt. Irradiation Flux Modelling for Thermal–Electrical Simulation of CubeSats: Orbit, Attitude and Radiation Integration. Energies. 2020; 13 (24):6691.
Chicago/Turabian StyleEdemar Morsch Filho; Laio Oriel Seman; Cezar Antônio Rigo; Vicente De Paulo Nicolau; Raúl García Ovejero; Valderi Reis Quietinho Leithardt. 2020. "Irradiation Flux Modelling for Thermal–Electrical Simulation of CubeSats: Orbit, Attitude and Radiation Integration." Energies 13, no. 24: 6691.
The efficiency of electric motors is being improved every day and projects with design variations can improve their performance. Among electric motors, the Permanent Magnet Synchronous Machine (PMSM) is being increasingly used, because of its growing use in electric vehicles. Simulating design variations using the Finite Element Method (FEM) can improve PMSM design, and by optimizing the parameters based on the FEM, even better results can be achieved. The design of the PMSM stator slots must be evaluated, as conductors are accommodated and an electrical potential is applied at this location. The FEM parameters are varied, and the results can be used to build an approximate model, known as a proxy model. The proxy model can then be used in a mathematical programming problem to optimize the design of stators that have less electric field in certain regions, thus reducing the chance of developing a failure. The results of the proposed methodology show that its application is promising for machine design and can also be used for the design of other systems.
Stéfano Frizzo Stefenon; Laio Oriel Seman; Clodoaldo Schutel Furtado Neto; Ademir Nied; Darlan Mateus Seganfredo; Felipe Garcia Da Luz; Pablo Henrique Sabino; José Torreblanca González; Valderi Reis Quietinho Leithardt. Electric Field Evaluation Using the Finite Element Method and Proxy Models for the Design of Stator Slots in a Permanent Magnet Synchronous Motor. Electronics 2020, 9, 1975 .
AMA StyleStéfano Frizzo Stefenon, Laio Oriel Seman, Clodoaldo Schutel Furtado Neto, Ademir Nied, Darlan Mateus Seganfredo, Felipe Garcia Da Luz, Pablo Henrique Sabino, José Torreblanca González, Valderi Reis Quietinho Leithardt. Electric Field Evaluation Using the Finite Element Method and Proxy Models for the Design of Stator Slots in a Permanent Magnet Synchronous Motor. Electronics. 2020; 9 (11):1975.
Chicago/Turabian StyleStéfano Frizzo Stefenon; Laio Oriel Seman; Clodoaldo Schutel Furtado Neto; Ademir Nied; Darlan Mateus Seganfredo; Felipe Garcia Da Luz; Pablo Henrique Sabino; José Torreblanca González; Valderi Reis Quietinho Leithardt. 2020. "Electric Field Evaluation Using the Finite Element Method and Proxy Models for the Design of Stator Slots in a Permanent Magnet Synchronous Motor." Electronics 9, no. 11: 1975.