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Impact of cognitive Effort, Social Interaction, Enjoyment of Learning, and Immersive Presence on Academic Achievement with Virtual Reality
No full textInternational audienceImmersive technologies represent significant advancements that allow users to engage in interactive and captivating environments, both perceptually and sensorily. This study aims to enrich the understanding of the relationship between several key variables and the achievement of academic objectives when using VR. An experiment was conducted with first-year university institute of technology students who participated in a virtual visit to a biology laboratory. The primary objective is to evaluate how each of the studied variables influences academic goals. By providing insights into the key factors that determine academic success in immersive environments, this research aims to optimize the use of these technologies in educational contexts, thereby enhancing students' learning outcomes
Experimental and modeling approach for estimating the psychological adaptation and perceived thermal comfort of occupants in indoor spaces
No full textInternational audienceThis study proposes a methodology for examining the relationship between environmental thermal conditions and occupant's perceived thermal comfort evaluation. Therefore, their psychological adaptation was examined to quantify and incorporate it in thermal comfort evaluations. To achieve the closure of the model's system of equations, experiments are carried out in which subjects are exposed to various thermal conditions in an enclosed space that simulates an office indoor environment; thermal measurements and perceived data are collected. Thus, the study aims to evaluate the adaptive factor that causes the difference between the physiological evaluation and the subjects' actual thermal perception. This adaptive factor is linked to the physical stimuli experienced owing to the thermal environment and the cognitive information within the occupant's memory systems; thus, the closure equation is derived from the outdoor air temperature and indoor operative temperature
Flow control in solar photovoltaics : Connecting coherent structures to heat transfer and particle transport
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Enhancing visible luminescence in sprayed-ZnO nanostructure through Cu doping
No full textInternational audienceCu-doped ZnO (CZO) is a low-cost, oxide-friendly material synthesized in various ratios (0%, 1%, 2%, and 3%) via spray pyrolysis on a glass substrate at 350 °C. SEM images revealed that the CZO films consist of aggregated spherical nanoparticles, each with a diameter of less than 20 nm. XRD and Raman measurements confirmed that the CZO thin films exhibit a polycrystalline wurtzite structure with a preferential 101̄1 orientation. The role of defects influencing the luminescence behavior of CZO films in the visible spectrum was investigated. Increasing the Cu content in ZnO crystals enhanced and produced four distinct color emissions in the visible photoluminescence spectrum: blue, green, yellow, and red. This rare occurrence in sprayed ZnO films is attributed to various defects, with the most prominent one being oxygen vacancies (Vo+–Vo++), zinc interstitials (Zni), and oxygen interstitials (Oi). Notably, the defects significantly decreased with the addition of 2 at. % Cu, unequivocally linked to the emergence of Zn vacancies (VZn). An increase in defects in the ZnO crystal leads to bandgap narrowing, from 3.273 to 3.202 eV. This study demonstrates that CZO films, synthesized through a cost-effective and straightforward method, are well-suited for optoelectronic applications
The counter-rotating mechanism makes a substantial contribution to balance-movement coordination during the anticipatory period of gait initiation
No full textInternational audienceMaintaining balance during gait initiation is essential for mobility and functional independence. The transition from a postural state to steady-state gait relies on two mechanisms to accelerate the whole-body centre of mass (WBCoM): moving centre of pressure (CoP); and counter-rotating segments to modulate internal whole-body angular momentum (HM). While the moving CoP mechanism is well-understood and known to generate mechanical instability, the role of the counter-rotating mechanism is less clear. Therefore, the present study quantified the contribution of the counter-rotating mechanism and explored its coordination with the moving CoP mechanism during the anticipatory period of gait initiation. Based on a sample of 13 healthy participants, we computed the time evolution of CoP, HM, the coefficient of cancellation (i.e., the extend to which segmental angular momenta counterbalance each other), and the relative contribution of each mechanism to WBCoM acceleration. We tested whether the contribution of the counter-rotating mechanism was significantly different from zero using a Statistical Parametric Mapping t-test. In the frontal plane, the counter-rotating mechanism did not appear to play a substantial role. However, in the sagittal plane, we found that: (1) the period of mechanical instability was longer than the period that have been identified based on the moving CoP mechanism alone; (2) rotational instability was reduced in anticipation of unipedal support; and (3) the counter-rotating mechanism significantly contributed to WBCoM forward acceleration. Overall, our findings emphasise the critical role of the counter-rotating mechanism in the sagittal plane for balance-movement coordination. Considering the counter-rotating mechanism appears important for understanding, assessing, and developing interventions for individuals with balance impairments
Real-time fuzzy logic-based direct power control for wind energy systems
No full textInternational audienceThis paper presents a fuzzy logic-based direct power control (F-DPC) strategy for wind turbines using double-fed induction generators (DFIGs) to improve power quality and system performance. In contrast to conventional direct power control (C-DPC), the proposed approach minimizes power ripple, improves response time and significantly reduces total harmonic distortion (THD). Simulation results show that F-DPC reduces THD from 7.06 % to 1.53 % in super-synchronous mode, from 4.88 % to 0.92 % in synchronous mode, and from 4.67 % to 1.18 % in sub-synchronous mode, achieving an average improvement of 78.08 %. In addition, F-DPC effectively reduces power ripple by 72.29 % for active power and 70.93 % for reactive power, as well as overshoot and steady-state error ensuring a more stable and efficient power conversion process. To assess its robustness, the performance of F-DPC is further evaluated under parametric variations, including a 100 % increase in winding resistances and a 20 % reduction in inductances. The results confirm that F-DPC maintains stable power regulation, reduced fluctuations and improved dynamic response, outperforming C-DPC in terms of power ripple, overshoot and steady-state error. To validate its real-time feasibility, the F-DPC strategy is implemented and tested on an OPAL-RT OP4512 real-time simulator using the RT-LAB platform. The real-time simulation results closely match the MATLAB/Simulink results, confirming that F-DPC maintains efficient power control under various operating conditions. These results highlight the practical scalability of F-DPC for real wind energy systems and demonstrate its potential to improve grid integration, power quality and overall system reliability
Intrication causale issue de la corrélation géodésique déterministe dans un espace-temps frémissant
No full textQuantenverschränkung gilt weithin als das rätselhafteste Merkmal der Quantenmechanik, da sie scheinbar den lokalen Realismus durch nichtlokale Korrelationen zwischen raumartig getrennten Teilchen verletzt. Obwohl die Verletzungen der Bell-Ungleichungen experimentell bestätigt wurden, beruht ihre Standarderklärung auf dem Kollaps der Wellenfunktion oder auf nichtlokalen verborgenen Variablen.In dieser Arbeit präsentieren wir eine alternative Erklärung auf Basis der Theorie der zitternden Raumzeit (TSRT). In diesem Rahmen erzeugen intrinsische Metrikfluktuationen Ensembles geodätischer Bahnen, die in der Eigenzeit synchronisiert sind. Ihre deterministischen Trajektorien führen zu statistischen Korrelationen im Raumzeitgefüge. Messergebnisse werden als geometrische Reaktionen auf diese fluktuierenden Hintergründe interpretiert, ohne dass ein quantenmechanischer Kollaps oder eine nichtlokale Einwirkung angenommen wird.Wir zeigen, dass die Clauser–Horne–Shimony–Holt (CHSH)-Ungleichung innerhalb einer lokal-kausalen geometrischen Struktur deterministisch verletzt werden kann. Diese Verletzungen entstehen als makroskopische Spuren gemeinsamer Raumzeitkrümmung und nicht aus quantenmechanischer Überlagerung. Die resultierende Korrelationsfunktion stimmt bei kurzen Distanzen mit den quantenmechanischen Vorhersagen überein, nimmt jedoch mit wachsendem Abstand ab — was überprüfbare Abweichungen in langbaseligen oder gravitationsmodulierten Experimenten erzeugt. TSRT liefert somit eine realistische, lorentzinvariante und widerlegbare Erklärung der Verschränkung, die auf der kausalen Struktur der Raumzeit basiert.Quantum entanglement is widely regarded as the most puzzling feature of quantum theory, apparently violating local realism through nonlocal correlations between spacelike-separated particles. Although violations of Bell inequalities are experimentally confirmed, their standard theoretical explanation relies on wavefunction collapse or nonlocal hidden variables.In this work, we present an alternative explanation based on Trembling Spacetime Relativity Theory (TSRT). In this framework, intrinsic metric fluctuations generate proper-time-synchronized geodesic ensembles whose deterministic trajectories give rise to statistical correlations across spacetime. Measurement outcomes are reinterpreted as geometric responses to these fluctuating backgrounds, without invoking quantum collapse or nonlocal influence.We show that the Clauser–Horne–Shimony–Holt (CHSH) inequality can be violated deterministically within a locally causal geometric structure. These violations emerge as macroscopic imprints of shared spacetime curvature, not quantum superposition. The resulting correlation function reproduces quantum predictions at short ranges but decays with separation—yielding testable deviations in long-baseline and gravitationally modulated experiments. TSRT thus offers a realist, Lorentz-invariant, and falsifiable account of entanglement grounded in the causal structure of spacetime.L’intrication quantique est largement considérée comme l’aspect le plus déroutant de la théorie quantique, semblant violer le réalisme local par des corrélations non locales entre des particules séparées par des intervalles d’espace-temps. Bien que les violations des inégalités de Bell soient confirmées expérimentalement, leur explication théorique standard repose sur l’effondrement de la fonction d’onde ou sur des variables cachées non locales.Dans ce travail, nous présentons une explication alternative fondée sur la théorie de la relativité de l’espace-temps tremblant (TSRT). Dans ce cadre, des fluctuations intrinsèques de la métrique génèrent des ensembles géodésiques synchronisés en temps propre, dont les trajectoires déterministes donnent lieu à des corrélations statistiques à travers l’espace-temps. Les résultats de mesure sont réinterprétés comme des réponses géométriques à ces arrière-plans fluctuants, sans recourir à un effondrement quantique ou à une influence non locale.Nous montrons que l’inégalité de Clauser–Horne–Shimony–Holt (CHSH) peut être violée de manière déterministe dans une structure géométrique localement causale. Ces violations émergent comme des empreintes macroscopiques d’une courbure d’espace-temps partagée, et non comme des effets de superposition quantique. La fonction de corrélation obtenue reproduit les prédictions quantiques à courte distance mais décroît avec la séparation — produisant ainsi des écarts testables dans des expériences à longue portée ou modulées gravitationnellement. La TSRT propose ainsi une interprétation réaliste, lorentz-invariante et falsifiable de l’intrication, ancrée dans la structure causale de l’espace-temps
Validation of a markerless motion capture system for centre of mass kinematic analysis
No full textInternational audienceIn recent years, markerless optical systems for biomechanical movement analysis in sports, gait and balance assessments are being used as an alternative to conventional marker based measuring systems. This study compares the performance of the Zed 2i stereoscopic camera against a VICON system in a standing position under three conditions: quiet standing and two movements simulating disturbances in two directions, anteroposterior and mediolateral. This study originates from a collaborative project with a medical team that aims to objectively evaluate balance function in patients recovering from stroke. The displacement and velocities of the centre of mass were calculated and compared in two directions, x and y. A Bland–Altman analysis for non-parametric data, along with the coefficient of determination and mean square error, were used for statistical evaluation. The results demonstrate that the limits of agreement in both sway tasks were greater than those observed in static conditions. However, the coefficient of determination of the sway tasks indicates a significant degree of agreement between the two systems. In contrast, in the static condition, it appears that noise may have a greater influence on the signal than the centre of mass estimate, due to the limitation of the depth algorithm used to estimate the joint positions
Mechanisms underlying the generation and generalisation of the surface layer
No full textInternational audienceWe define ‘surface layer’ (SL) as an inertia-dominated turbulence region outside a viscous or roughness surface-adjacent sub-layer (SAS) that is characterised by linear scaling of specific coherence length scales on wall-normal distance, . We generalise the mechanisms that underlie the formation of the classical inertial SL in the shear-dominated turbulent boundary layer (TBL) to wall-bounded turbulent flows with zero mean shear. Using particle image velocimetry data from two wind tunnel facilities, we contrast the classical TBL SL with a non-classical shear-free SL generated within grid turbulence advected over an impermeable plate using two grids with different turbulence length scales. Integral-scale variations with and other statistics are quantified. In both shear-dominated and shear-free SLs we observe well-defined linear increases in of the streamwise integral scale of vertical velocity fluctuations. In grid turbulence the shear-free SL initiates just above the SAS that confines friction-generated motions. By contrast, the TBL SL forms with non-zero mean shear rate that extends streamwise coherence lengths of streamwise fluctuations. In both flow classes only the integral scales of vertical fluctuating velocity increase linearly with , indicating that the SL is generated by the blockage of vertical fluctuations in the vertical. Whereas the SAS in the TBL is much thinner than in the grid-turbulence flows, the generation of a shear-free SL by the interaction of turbulence eddies and a surface depends on the relative thinness of the SAS. We conclude that the common generalisable SL mechanism is direct blockage of vertical fluctuations by the impermeable surface
