2024
Autores
Lopes, R; Pinto, SM; Parente, MPL; Moreira, PMGP; Baptista, AJ;
Publicação
JOURNAL OF ENGINEERING DESIGN
Abstract
The transportation industry focuses on reducing vehicle weight for fuel economy and emissions. This emphasis promotes the use of coaches, which raises concerns about passenger safety in frontal collisions. The proposal is to correlate the crashworthiness of coaches with the replacement of fibreglass composite materials by a state-of-the-art polymer (DCPD). Based on the ECE R29 standard, FEM models solved by Pamcrash (R) assess the vehicle's crashworthiness. Cross-referencing these results with the Eco-Design X technique, two models are evaluated in terms of environmental impact. The LeanDfX methodology involves multiple analyses for design domains, including model optimisation, manufacturing processes, and eco-design. On a performance scale of 0% to 100%, different 'X' domains are evaluated. The Eco-Design study allowed the assessing the environmental impacts of the proposed solution compared to the original models, is conducted using Simapro v9.2.0.2 and the ReCiPe 2016 methodology. The novel design proposed modifications to the models resulted in significant structural behaviour improvements for driver's physical integrity. The cross results of Design-for-Crashworthiness and Design-for-Eco-Design using the innovative LeanDfX framework provide a new perspective to be integrated into the automotive industry. The use of DCPD is expected to lead to a more crashworthy and environmentally friendly design, while ensuring passenger safety.
2024
Autores
Miranda, M; Tanimura, Y; Haga, J; Ruhela, A; Harrell, SL; Cazes, J; Macedo, R; Pereira, J; Paulo, J;
Publicação
SC24-W: Workshops of the International Conference for High Performance Computing, Networking, Storage and Analysis, Atlanta, GA, USA, November 17-22, 2024
Abstract
Modern supercomputers host numerous jobs that compete for shared storage resources, causing I/O interference and performance degradation. Solutions based on software- defined storage (SDS) emerged to address this issue by coordinating the storage environment through the enforcement of QoS policies. However, these often fail to consider the scale of modern HPC infrastructures.In this work, we explore the advantages and shortcomings of state-of-the-art SDS solutions and highlight the scale of current production clusters and their rising trends. Furthermore, we conduct the first experimental study that sheds new insights into the performance and scalability of flat and hierarchical SDS control plane designs.Our results, using the Frontera supercomputer, show that a flat design with a single controller can scale up to 2,500 nodes with an average control cycle latency of 41 ms, while hierarchical designs can handle up to 10,000 nodes with an average latency ranging between 69 and 103 ms. © 2024 IEEE.
2024
Autores
Abd El Dayem, K; GRAVITY Collaboration; Abuter, R; Aimar, N; Seoane, PA; Amorim, A; Beck, J; Berger, JP; Bonnet, H; Bourdarot, G; Brandner, W; Cardoso, V; Dolcetta, RC; Clénet, Y; Davies, R; de Zeeuw, PT; Drescher, A; Eckart, A; Eisenhauer, F; Feuchtgruber, H; Finger, G; Schreiber, NMF; Foschi, A; Gao, F; Garcia, P; Gendron, E; Genzel, R; Gillessen, S; Hartl, M; Haubois, X; Haussmann, F; Heissel, G; Henning, T; Hippler, S; Horrobin, M; Jochum, L; Jocou, L; Kaufer, A; Kervella, P; Lacour, S; Lapeyrère, V; Le Bouquin, JB; Léna, P; Lutz, D; Mang, F; More, N; Ott, T; Paumard, T; Perraut, K; Perrin, G; Pfuhl, O; Rabien, S; Ribeiro, DC; Bordoni, MS; Scheithauer, S; Shangguan, J; Shimizu, T; Stadler, J; Straub, O; Straubmeier, C; Sturm, E; Tacconi, LJ; Urso, I; Vincent, F; von Fellenberg, SD; Widmann, F; Wieprecht, E; Woillez, J; Zhang, F;
Publicação
ASTRONOMY & ASTROPHYSICS
Abstract
Studying the orbital motion of stars around Sagittarius A* in the Galactic center provides a unique opportunity to probe the gravitational potential near the supermassive black hole at the heart of our Galaxy. Interferometric data obtained with the GRAVITY instrument at the Very Large Telescope Interferometer (VLTI) since 2016 has allowed us to achieve unprecedented precision in tracking the orbits of these stars. GRAVITY data have been key to detecting the in-plane, prograde Schwarzschild precession of the orbit of the star S2 that is predicted by general relativity. By combining astrometric and spectroscopic data from multiple stars, including S2, S29, S38, and S55 - for which we have data around their time of pericenter passage with GRAVITY - we can now strengthen the significance of this detection to an approximately 10 sigma confidence level. The prograde precession of S2's orbit provides valuable insights into the potential presence of an extended mass distribution surrounding Sagittarius A*, which could consist of a dynamically relaxed stellar cusp comprising old stars and stellar remnants, along with a possible dark matter spike. Our analysis, based on two plausible density profiles - a power-law and a Plummer profile - constrains the enclosed mass within the orbit of S2 to be consistent with zero, establishing an upper limit of approximately 1200 M-circle dot with a 1 sigma confidence level. This significantly improves our constraints on the mass distribution in the Galactic center. Our upper limit is very close to the expected value from numerical simulations for a stellar cusp in the Galactic center, leaving little room for a significant enhancement of dark matter density near Sagittarius A*.
2024
Autores
Fernandes, P; Nunes, S; Santos, L;
Publicação
Proceedings of the 2024 Joint International Conference on Computational Linguistics, Language Resources and Evaluation, LREC/COLING 2024, 20-25 May, 2024, Torino, Italy.
Abstract
Data-to-text systems offer a transformative approach to generating textual content in data-rich environments. This paper describes the architecture and deployment of Prosebot, a community-driven data-to-text platform tailored for generating textual summaries of football matches derived from match statistics. The system enhances the visibility of lower-tier matches, traditionally accessible only through data tables. Prosebot uses a template-based Natural Language Generation (NLG) module to generate initial drafts, which are subsequently refined by the reading community. Comprehensive evaluations, encompassing both human-mediated and automated assessments, were conducted to assess the system's efficacy. Analysis of the community-edited texts reveals that significant segments of the initial automated drafts are retained, suggesting their high quality and acceptance by the collaborators. Preliminary surveys conducted among platform users highlight a predominantly positive reception within the community.
2024
Autores
Fonseca, T; Leao, G; Ferreira, LL; Sousa, A; Severino, R; Reis, LP;
Publicação
2024 IEEE INTERNATIONAL CONFERENCE ON AUTONOMOUS ROBOT SYSTEMS AND COMPETITIONS, ICARSC
Abstract
This paper explores the use of Robotics and decentralized Multi-Agent Reinforcement Learning (MARL) for side-by-side navigation in Intelligent Wheelchairs (IW). Evolving from a previous work approach using traditional single-agent methodologies, it adopts a Multi-Agent Deep Deterministic Policy Gradient (MADDPG) algorithm to provide control input and enable a pair of IW to be deployed as decentralized computing agents in real-world environments, discarding the need to rely on communication between each other. In this study, the Flatland 2D simulator, in conjunction with the Robot Operating System (ROS), is used as a realistic environment to train and test the navigation algorithm. An overhaul of the reward function is introduced, which now provides individual rewards for each agent and revised reward incentives. Additionally, the logic for identifying side-by-side navigation was improved, to encourage dynamic alignment control. The preliminary results outline a promising research direction, with the IWs learning to navigate in various realistic hallways testing scenarios. The outcome also suggests that while the MADDPG approach holds potential over single-agent techniques for the decentralized IW robotics application, further investigation are needed for real-world deployment.
2024
Autores
Ferreira, L; Sousa, JJ; Lourenço, JM; Peres, E; Morais, R; Pádua, L;
Publicação
SENSORS
Abstract
Understanding geometric and biophysical characteristics is essential for determining grapevine vigor and improving input management and automation in viticulture. This study compares point cloud data obtained from a Terrestrial Laser Scanner (TLS) and various UAV sensors including multispectral, panchromatic, Thermal Infrared (TIR), RGB, and LiDAR data, to estimate geometric parameters of grapevines. Descriptive statistics, linear correlations, significance using the F-test of overall significance, and box plots were used for analysis. The results indicate that 3D point clouds from these sensors can accurately estimate maximum grapevine height, projected area, and volume, though with varying degrees of accuracy. The TLS data showed the highest correlation with grapevine height (r = 0.95, p < 0.001; R2 = 0.90; RMSE = 0.027 m), while point cloud data from panchromatic, RGB, and multispectral sensors also performed well, closely matching TLS and measured values (r > 0.83, p < 0.001; R2 > 0.70; RMSE < 0.084 m). In contrast, TIR point cloud data performed poorly in estimating grapevine height (r = 0.76, p < 0.001; R2 = 0.58; RMSE = 0.147 m) and projected area (r = 0.82, p < 0.001; R2 = 0.66; RMSE = 0.165 m). The greater variability observed in projected area and volume from UAV sensors is related to the low point density associated with spatial resolution. These findings are valuable for both researchers and winegrowers, as they support the optimization of TLS and UAV sensors for precision viticulture, providing a basis for further research and helping farmers select appropriate technologies for crop monitoring.
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