2024
Autores
Salgado, P; Perdicoullis, T; dos Santos, PL; Afonso, PAFNA;
Publicação
2024 IEEE 24TH INTERNATIONAL SYMPOSIUM ON COMPUTATIONAL INTELLIGENCE AND INFORMATICS, CINTI
Abstract
Knowledge models often use hierarchical structures, which help break down complex data into manageable components. This enables better understanding and aids in reasoning and decision-making. Hierarchical structures are effective in organizing, managing, and processing complex information. Traditional Self-Organizing Maps are typically flat, two-dimensional grids for visualizing and grouping data. They can be shaped into hierarchical structures, offering benefits such as improved data representation, scalability, enhanced grouping and visualization, and hierarchical feature extraction while preserving data topology. This paper introduces a self-organizing hierarchical map with an appropriate topology and a suitable learning mechanism for retaining information in an organized way. In this conceptual model, information is selectively absorbed in each layer. These characteristics make the Hierarchical Self-organising Maps a powerful non-linear classifier. Simulations are conducted to test and evaluate the performance of this neural structure as a classifier.
2024
Autores
Barros, FS; Graça, PA; Lima, JJG; Pinto, RF; Restivo, A; Villa, M;
Publicação
ENGINEERING APPLICATIONS OF ARTIFICIAL INTELLIGENCE
Abstract
Solar wind forecasting is a core component of Space Weather, a field that has been the target of many novel machine-learning approaches. The continuous monitoring of the Sun has provided an ever-growing ensemble of observations, facilitating the development of forecasting models that predict solar wind properties on Earth and other celestial objects within the solar system. This enables us to prepare for and mitigate the effects of solar wind-related events on Earth and space. The performance of some simulation-based solar wind models depends heavily on the quality of the initial guesses used as initial conditions. This work focuses on improving the accuracy of these initial conditions by employing a Recurrent Neural Network model. The study's findings confirmed that Recurrent Neural Networks can generate better initial guesses for the simulations, resulting in faster and more stable simulations. In our experiments, when we used predicted initial conditions, simulations ran an average of 1.08 times faster, with a statistically significant improvement and reduced amplitude transients. These results suggest that the improved initial conditions enhance the numerical robustness of the model and enable a more moderate integration time step. Despite the modest improvement in simulation convergence time, the Recurrent Neural Networks model's reusability without retraining remains valuable. With simulations lasting up to 12 h, an 8% gain equals one hour saved per simulation. Moreover, the generated profiles closely match the simulator's, making them suitable for applications with less demanding physical accuracy.
2024
Autores
Oliveira, AJ; Villa, M; Ferreira, BM; Cruz, NA;
Publicação
2024 IEEE/OES AUTONOMOUS UNDERWATER VEHICLES SYMPOSIUM, AUV
Abstract
This study addresses the sonar perceptual ambiguity problem inherent in underwater sonar-based SLAM systems, resulting from the sonar's wide beam aperture. We propose a SLAM algorithm that integrates a free-space mapping approach with a particle filter, leveraging polar-based acoustic images collected from an MSIS. Our method utilizes grid maps to compile information on empty regions, aiming at improving mapping accuracy. Free-space representations are further leveraged for particle filter weight update via scan matching. The centre-of-mass map cell representation is exploited for efficient weight update using simple matrix operations. Illustrative experimental results are provided, based on real data collected from a testing pool environment.
2024
Autores
Umaraliev, R; Zaginaev, V; Sakyev, D; Tockov, D; Amanova, M; Makhmudova, Z; Nazarkulo, K; Abdrakhmatov, K; Nizamiev, A; Moura, R; Blanchard, K;
Publicação
Geologija
Abstract
2024
Autores
Moura, R; Lomas, LA; Almeida, F;
Publicação
International Multidisciplinary Scientific GeoConference Surveying Geology and Mining Ecology Management, SGEM
Abstract
Geophysical studies on the lunar surface have, in the past, used various methods that contribute not only towards the knowledge of the lunar subsurface but also contribute towards the design of future lunar missions, namely those that will, in the near future, take humans to the Moon’s surface. This work analyzes a specific set of ground penetrating radar (GPR) data, collected during the Chang’E-4 mission of the Chinese Space Agency, using theYutu-2 rover within the von Kármán crater, on the far-side of the Moon. From this dataset two electrical parameters were estimated. The approach uses the backscatter of the electromagnetic wavefield in order to obtain estimates of the real component of the complex relative permittivity as well as the electrical resistivity. © 2024 International Multidisciplinary Scientific Geoconference. All rights reserved.
2024
Autores
Ribeiro R.; Moura R.; Carvalho A.; Lima A.; Gumiaux C.;
Publicação
International Multidisciplinary Scientific GeoConference Surveying Geology and Mining Ecology Management, SGEM
Abstract
Raw materials are essential for Europe’s industrial base, as they are used to produce vital goods and technologies. The European Comission’s assessment identifies lithium and tin as critical and strategic raw materials due to rising demand. A PhD thesis aims to create a 3D geological model of the Argemela District in Central Portugal to provide vital information about the genesis of the hydrothermal tin and lithium mineralizations founded in the region. The study places emphasis on the very-low-frequency (VLF) electromagnetic method as a tool to provide information about the mineralization, lithologic contacts, and structural features that can be related to the mineralizations. Argemela district has two main areas, the Argemela Tin and Lithium Mine and the Argemela Hill Top. VLF data was collected and analyzed, showing that low resistivity may be associated with mineralization in the Argemela Mine, while high resistivity may be linked to the Argemela microgranite in the Argemela Hill Top. This geophysical method is effective in non-invasively mapping subsurface features, assisting in the development of a comprehensive 3D geological model and enhancing resource evaluation.
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