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A comprehensive performance evaluation of bifacial photovoltaic modules: insights from a year-long experimental study conducted in the Canadian climate
No full textInternational audienceBifacial photovoltaic (PV) modules, capable of capturing solar energy from both sides of the cells, are becoming increasingly popular as their manufacturing costs approach those of traditional monofacial modules. Accurate estimation of their power generation capacity is essential for optimizing their use. This study evaluates a power production model for bifacial PV modules using local irradiance data from Razon+ in Sherbrooke, Canada, and Solcast irradiance data derived from satellite imagery and weather models. The model's performance was assessed throughout the year, with particular attention to the impact of snow coverage during winter. To address computational efficiency, the study evaluated ray tracing and a 2D view factor model, selecting the more time-efficient method. Experimental validation showed that, using local irradiance data, the model achieved Normalized Root Mean Square Errors (NRMSE) of 18.77%, 4.94%, 3.93%, and 6.22% for winter, spring, summer, and fall, respectively. With Solcast data, the NRMSEs were 22.76%, 15.32%, 14.72%, and 17.78% for the corresponding seasons. While the model performed satisfactorily in spring, summer, and fall, it was less accurate in winter. To enhance winter accuracy, the model incorporated snow coverage, using snow depth as a metric to detect snow on the front surface. This adjustment improved the accuracy by 51.1%
Comportement hydrodynamique et cavitant d'une pompe innovante avec rotation indépendante de l'inducteur et de la roue centrifuge
No full textOver the years, the technology that enables rotors in turbomachines to rotate independently, especially in counter-rotating configurations, has captured the interest of numerous researchers and industries. The study of the effect of this technology on the turbine, compressor and axial pumps has shown its important effect on the characteristics of the turbomachines. Until now, no research has been done on the effect of independent rotation of inducer and impeller in pumps. In this thesis, the influence of the independent rotation of the inducer and impeller on pump characteristics has been investigated for the first time, using both experimental and numerical methods. To meet this aim, the impeller and both co-rotation and counter-rotation inducer were designed for independent rotation. This design permits the investigation of three parameters not possible to evaluate in the conventional pump when the inducer and impeller are linked and rotated together. The parameters studied in this research are the rotational speed of the inducer, the distance between the inducer and the impeller, and the direction of the inducer rotation. To examine these parameters, a new experimental test bench was designed. A separate shaft and electric motor were incorporated to ensure that the speed of the inducer could be adjusted without influencing the rotation of the impeller, enabling independent rotation of the inducer. The direction of rotation for the inducer was changed by keeping its geometry consistent and reversing the blade orientation, leading to a counter-rotating inducer. Furthermore, to adjust the distance between the inducer and the impeller, a slider was incorporated within the inducer section, allowing for modification of the distance between the inducer and the impeller. The investigation into pump characteristics is divided into two main parts: the analysis of characteristics in non-cavitation condition and the study of cavitation performance. The independent rotation of the inducer enhances the pump characteristics in both cavitation and non-cavitation conditions.Au fil des années, la technologie permettant aux rotors des turbomachines de tourner indépendamment, notamment dans des configurations en contre-rotation, a suscité l'intérêt de nombreux chercheurs et industries. L'étude de l'effet de cette technologie sur la turbine, le compresseur et les pompes axiales a montré son impact significatif sur les caractéristiques des turbomachines. Jusqu'à présent, aucune recherche n'a été menée sur l'effet de la rotation indépendante de l'inducteur et de la roue dans les pompes. Dans cette thèse, l'influence de la rotation indépendante de l'inducteur et de la roue sur les caractéristiques de la pompe a été étudiée pour la première fois, en utilisant à la fois des méthodes expérimentales et numériques. Pour atteindre cet objectif, la roue et l'inducteur en co-rotation et en contre-rotation ont été conçus pour une rotation indépendante. Cette conception permet d'étudier trois paramètres impossibles à évaluer dans la pompe conventionnelle lorsque l'inducteur et la roue sont liés et tournent ensemble. Les paramètres étudiés dans cette recherche sont la vitesse de rotation de l'inducteur, la distance entre l'inducteur et la roue, et la direction de rotation de l'inducteur. Pour examiner ces paramètres, un nouveau banc d'essai expérimental a été conçu. Un arbre séparé et un moteur électrique ont été intégrés pour garantir que la vitesse de l'inducteur puisse être ajustée sans influencer la rotation de la roue, permettant une rotation indépendante de l'inducteur. La direction de rotation de l'inducteur a été modifiée en conservant sa géométrie et en inversant l'orientation des aubes, conduisant à un inducteur en contre-rotation. De plus, pour ajuster la distance entre l'inducteur et la roue, un curseur a été intégré dans la section de l'inducteur, permettant de modifier la distance entre l'inducteur et la roue. L'étude des caractéristiques de la pompe est divisée en deux parties principales : l'analyse des caractéristiques en condition de non-cavitation et l'étude des performances en cavitation. La rotation indépendante de l'inducteur améliore les caractéristiques de la pompe dans les conditions de cavitation et de non-cavitation
Exploration des synergies entre les technologies immersives et l’Intelligence Artificielle pour un Enseignement Inclusif
No full textInternational audienceCet article s’inscrit dans un travail de recherche plus global, un projet de thèse CIFRE, qui a débuté en janvier 2024. Le projet de recherche vise à explorer l’impact de l’intégration de la Réalité Virtuelle et l’Intelligence Artificielle sur les différents âges d’apprenants en termes d’inclusion et d’accessibilité. L’objectif est de comprendre comment ces technologies redéfinissent l’éducation à l’ère numérique, et concevoir par la suite un environnement virtuel pour la recherche. Dans cet article, nous présentons le projet de thèse et un aperçu du cadre théorique sur lequel il s’appuiera, ainsi que la méthodologie de recherche à poursuivre
Terahertz nondestructive stratigraphic reconstruction of paper stacks based on adaptive sparse deconvolution
No full textInternational audienceCharacterizing the number of sheets in a stack of paper typically involves mechanical separation of the individual sheets. Here, we explore an nondestructive method that can be applied to the intact paper stack. Namely, terahertz time-of-flight tomography, together with post signal-processing technique sparse deconvolution based on a two-step iterative shrinkage-thresholding algorithm (SD/TWIST), is employed to reconstruct the stratigraphy of stacks of sheets of paper with multilayered structure in a nondestructive and noncontact manner. The double-Gaussian mixture model (DGMM) is also incorporated to suppress dispersion in the reflected THz echoes. The effectiveness and accuracy of the proposed adaptive sparse-deconvolution method are verified experimentally and numerically. Compared with the commonly used frequency wavelet-domain deconvolution (FWDD) method and previous implementations of sparse deconvolution based on an iterative-shrinkage and thresholding algorithm (SD/IST), the proposed sparse-deconvolution approach can provide a clearer and rapid stratigraphic reconstruction of the paper stacks studied, while ensuring accurate thickness information for each paper sheet in the presence of noise, revealing the potential usage of real-time THz tomographic-image processing
A Deep Reinforcement Learning Framework and Methodology for Reducing the Sim-to-Real Gap in ASV Navigation
No full textInternational audienceDespite the increasing adoption of Deep Reinforcement Learning (DRL) for Autonomous Surface Vehicles (ASVs), there still remain challenges limiting real-world deployment. In this paper, we first integrate buoyancy and hydrodynamics models into a modern Reinforcement Learning framework to reduce training time. Next, we show how system identification coupled with domain randomization improves the RL agent performance and narrows the sim-to-real gap. Real-world experiments for the task of capturing floating waste show that our approach lowers energy consumption by 13.1\% while reducing task completion time by 7.4\%. These findings, supported by sharing our open-source implementation, hold the potential to impact the efficiency and versatility of ASVs, contributing to environmental conservation efforts
Intelligence géospatiale maritime et sciences de l’espace géographique : regards croisés
No full textInternational audienc
Intégration de la rétroaction haptique dans les appareils intelligents : interfaces multimodales et directives de conception
No full textThe growing interest in integrating haptic feedback into commercial products is a direct result of advancements in haptic technology. Notably, the proliferation of smartphones and tablets has led to the integration of haptic modalities for various interfaces.While extensive research has explored the integration of sensory modalities (visual, auditory, tactile) in passive touch, there is a relative dearth of knowledge regarding bimodality or multimodality in the context of active touch. Emerging technologies, like surface haptics, offer opportunities to investigate various aspects related to sensory integration.This work provides valuable guidelines for developers, drawing from experimental studies in the realm of active touch. Our initial investigation focuses on the temporal relationship between audio and tactile feedback, revealing a critical 200 ms threshold during sliding interactions on a haptic surface. Moreover, we identify an acceptable audio-tactile delay of 109 ms for click gestures with virtual buttons, emphasizing the need to prohibit or minimize haptic delay to less than 40 ms. A comparative study involving sighted and blind individuals unveils a crucial aspect of inclusion: adhering to synchronization boundaries of the sighted population, relative to virtual buttons, allows for the inclusive design of interfaces accommodating both populations.Additionally, we explore the impact of factors such as stereoscopy and surface deformation on the perception of texture roughness, demonstrating that their presence can alter the perceived roughness of smooth textures by over 20%.Furthermore, our research explores the potential of using vibration headphones for object localization, revealing a sensitivity of 7° for the haptic modality, 8° for auditory feedback, and 6° for audio-tactile. This highlights not only the viability of haptic feedback in virtual reality for object localization but also the improvement achieved by reinforcing the sensory experience with audio-tactile stimuli.L'intérêt croissant pour l'intégration de la rétroaction haptique dans les produits commerciaux est directement lié aux progrès de la technologie haptique. Notamment, la prolifération des smartphones et des tablettes a conduit à l'intégration de modalités haptiques pour diverses fonctions.Alors que des recherches approfondies ont exploré l'intégration des modalités sensorielles (visuelle, auditive, tactile) dans le toucher passif, il existe un manque relatif de connaissances en ce qui concerne la bimodalité ou la multimodalité dans le contexte du toucher actif. Les technologies émergentes, telles que l'haptique de surface, offrent des opportunités pour étudier divers aspects liés à l'intégration sensorielle.Ce travail fournit des lignes directrices précieuses pour les développeurs, tirées d'études expérimentales dans le domaine du toucher actif. Notre première investigation se concentre sur la relation temporelle entre les retours audio et tactiles, révélant un seuil critique de 200 ms lors des interactions de glissement sur une surface haptique. De plus, nous identifions un délai audio-tactile acceptable de 109 ms pour les gestes de clic avec des boutons virtuels, soulignant la nécessité de prohiber ou de minimiser le délai haptique à moins de 40 ms. Une étude comparative impliquant des individus voyants et aveugles dévoile un aspect crucial de l'inclusion : le respect des limites de synchronisation audio-tactile de la population voyante, concerne les boutons virtuels, permet la conception inclusive d'interfaces adaptées aux deux populations. De plus, nous explorons l'impact de facteurs tels que la stéréoscopie et la déformation de surface sur la perception de la rugosité des textures, démontrant que leur présence peut altérer la rugosité perçue des textures lisses de plus de 20%.En outre, notre recherche explore le potentiel de l'utilisation de casques vibrants pour la localisation d'objets, révélant une sensibilité de 7° pour la modalité haptique, de 8° pour la rétroaction auditive et de 6° pour la rétroaction audio-tactile. Cela met en évidence non seulement la viabilité de la rétroaction haptique en réalité virtuelle pour la localisation d'objets, mais aussi l'amélioration obtenue en renforçant l'expérience sensorielle avec des stimuli audio-tactiles
Robot Parallèle à Câbles Reconfigurable pour la Culture Hydroponique sous Serre
No full textInternational audienc
Introduction to Autonomous Navigation and Mapping for Unmanned Ground Vehicles
No full textThis technical report addresses the fundamental challenges associated with Navigation and Mapping for Unmanned Ground Vehicles (UGVs), with a particular focus on wheeled robots. Aimed at students beginning robotics research projects, this document provides an overview of the fundamentals of UGV navigation and mapping. Notably, it introduces perception, localization, mapping, and autonomous navigation, with an emphasis on the associated challenges
DRGAT: Dual-relational graph attention networks for aspect-based sentiment classification
No full textInternational audienceAspect-based sentiment classification has become a popular topic in natural language processing. Exploiting dependency syntactic information with graph neural networks has recently become a popular trend. Despite their success, methods that rely heavily on a dependency tree face major challenges. This concerns the alignment of aspects and their word sentiments due tothe richness of the language and the fact that a dependency tree might produce noisy signals from unrelated associations. This paper introduces a Dual-Relational Graph Attention Network (DRGAT) that fully exploits syntactic structural information and then the sentiment-aware context (e.g., phrase segmentation and hierarchical structure) of the constituent tree of a sentence.Additional constituency and dependency attention mechanisms provide comprehensive syntactic information across words, thereby enabling an accurate connection between aspect words and corresponding sentiment words. Considering that the original parsed constituency tree may have a large depth, this could lead to words being far apart increasing the computational overhead. The constituency tree of each sentence is dynamically reconstructed by determining the importance of each relational node. Extensive experimental results on six English datasets demonstrated that fully exploiting syntactic information can achieve excellent sentiment classification results