Portail des publications scientifiques IMT Mines Alès
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Exploration des interfaces dent-céramique : une approche avancée avec l‘imagerie numérique rapide ou l‘interférométrie
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UV protection enhancement in miscanthus x giganteus via e-beam radio-grafting
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Techniques d’imagerie pour la mesure en mécanique des fluides
No full textInternational audienceImaging is a technique used in various fields related to fluid mechanics. It allows the measurement of geometric parameters such as size and shape, as well as scalar field variables like temperature, pH, and mixture.This article provides an overview digital imaging and its application in fluid mechanics. It presents the main experimental setups used and their implementation. The aspects of signal processing and information management, crucial in this context, are also addressed. Finally, the article illustrates the potential of the technique through several examples of applications emphasizing coupling and ultra-fast imaging.L'imagerie est une technique utilisée dans de nombreux domaines liés à la mécanique des fluides. Elle permet de mesurer des paramètres géométriques (taille, forme…), ainsi que des champs de grandeurs scalaires (température, pH, mélange…).Cet article propose une vue d’ensemble de l’imagerie et de son application en mécanique des fluides. Il présente les principaux montages expérimentaux utilisés, ainsi que leur mise en œuvre. Les aspects traitement du signal et gestion de l'information, essentiels dans ce cas, sont également abordés. Enfin, l'article illustre le potentiel de la technique via plusieurs exemples d'applications mettant l'accent sur le couplage et l'imagerie ultrarapide
Active trachoma: enhancing image classification using pretrained SOTA models and explainable AI
No full textInternational audienceBackground Trachoma, an infectious disease that leads to blindness, continues to pose a significant public health challenge in over 40 countries as of 2023. The initial phase of this disease, “active trachoma” is characterized by inflammation and can be effectively treated with non-surgical interventions. However, if left untreated, it progresses to the “scarring” phase, often requiring surgical intervention. Earlier detection of “active trachoma” is critical to prevent unnecessary surgery and also to reduce the transmission of the infection. Developing accessible tools for a region with limited resources is necessary. Deep neural networks have proven their effectiveness in numerous image and vision-related tasks, yet research on “active trachoma” has received still little attention. Method In this study, we adapted several pre-trained state-of-the-art deep neural network models like ResNet, Xception from image classification on “active classification” task. Further experiments were also conducted in three cases: training from scratch, training from pretrained models on raw images and on region-of-interest (ROI) focused images. Results and discussion The results indicate that these models outperformed the previous studies using the same dataset, achieving an improvement of 6\% on detection of follicular trachomatous inflammation and 12\% for detection of intense trachomatous inflammation. Furthermore, we employed the eXplainable Artificial Intelligence tool Grad-CAM, which revealed a significant discrepancy between eyelid's geometric centroid and attention centroid from models with high classification accuracy. This finding suggests that the conventional method of selecting a region of interest based on the geometric centroid may need to be adjusted. Using XAI can offer valuable insights into understanding the classification and progression of active trachoma
Supercritical CO2 assisted extrusion foaming of PLA- cellulose fibre composites: effect of fibre on foam processing and morphology
No full textInternational audienceThis work is focused on the effect of the content and length of cellulose fibres on PLA foams produced by extrusion-foaming process assisted by sc-CO2. The produced foamed samples were characterised by water pycnometry, modulated differential scanning calorimetry, and scanning electron microscopy. Increasing the length and the content of cellulose fibres results in a reduction of the expansion of the foams at a given die temperature. Nevertheless, long fibres at low content allows an increase of the longitudinal expansion of the foams. Furthermore, composite foams can be processed at a lower die temperature than neat PLA, providing a wider processing window. In general, the addition of cellulose fibres increases the crystallinity of the foams. Narrower cell size distributions and smaller cells are obtained when adding fibres, implying more homogeneous foam structure
Centroid human tracking via oriented detection in overhead fisheye sequences
No full textInternational audiencePedestrian tracking is highly relevant to the understanding of static and moving scenes in video sequences. The increasing demand for people’s safety and security has resulted in more research on intelligent visual surveillance in a wide range of applications, such as moving human detection and tracking. With the great success of deep learning methods, researchers decided to switch from traditional methods based on hand-crafted feature extractors to recent deep-learning-based techniques in order to detect and track people. In this work, the topic of person detection using a Top-view moving fisheye camera is addressed using a deep learning detector combined with a centroid technique in order to track a selected person. Although the fisheye camera is a useful tool for video monitoring, most object detection techniques use classical perspective cameras, with (or without) deep learning. However, due to the distortions of fisheye images, we expect to have higher requirements and challenges on pedestrian detection using this type of device. In this paper, an end-to-end people detection learning method is proposed; it is based on a YOLOv3 detector that detects people using oriented bounding boxes. The proposed model customizes the traditional YOLOv3 for the detection of oriented bounding boxes, by regressing the angle of each bounding box using a periodic loss function. With rotation bounding box prediction, the new approach is efficient, reaching 98.1% of true detection. This detection model is combined with a centroid tracker in order to track a single person by identifying the trajectory, estimated angle of rotation and target distance. Finally, the proposed method is evaluated on a new available dataset where rotated bounding boxes represent annotations from several fisheye videos
Impact of group synchrony, postural stability and agency on cybersickness symptoms
No full textInternational audienceVirtual Reality (VR) is a developing technology for computer-mediated communication (CMC). Nevertheless, challenges remain that are impeding the adoption of VR for social interactions such as cybersickness, characterized by symptoms like motion sickness, such as nausea, dizziness, and eyestrain. According to the postural instability hypothesis (Riccio & Stoffregen, 1991), cybersickness could result from postural instability due to alterations of postural control. Therefore, greater postural instability increases the likelihood and severity of motion sickness. Interestingly, postural stability is often studied in single participants, yet, a few studies suggested that intentional social synchronization leads to greater postural stability. Consequently, group synchrony, characterized by the temporal coordination of movement between individuals, could increase postural stability and, therefore, reduce cybersickness.The present study investigated this hypothesis by conducting a study in VR setting exploring the role of intentional group synchronization on postural stability and cybersickness symptoms. Groups of participants (7 triads) completed oscillatory movements with their right arm in SOLO, TOGETHER and SYNCHRO conditions, manipulating visual coupling and synchronization instructions. Between experimental blocs, participants completed the Simulator Sickness Questionnaire (SSQ, Bouchard et al., 2007) and the Sense of Agency Scale (SoA, Hurault et al., 2020).This study replicated previous findings showing the impact of visual coupling and instructions to synchronize on group synchrony (Alderisio et al., 2017; Bardy et al., 2020). Furthermore, this study expanded previous findings observed in dyads, showing (ii) an impact of group synchrony on postural stability (Gueugnon et al., 2016; Varlet et al., 2011). However, there was no impact of synchrony or body sway on cybersickness symptoms but an association between the sense of agency and cybersickness, suggesting that the successful binding of actions and their consequences could prevent the occurrence of cybersickness symptoms. To conclude, this exploratory study did not confirm the postural stability hypothesis but suggested that synchronized social interactions in a VR environment do not generate cybersickness symptoms. Instead, synchrony could stabilize postural coordination through interpersonal influences, paving the way for social interventions in clinical populations
Eco-friendly Materials based on Low-Density Polyethylene, Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) and EGMA
No full textInternational audienceThe widespread use of polyethylene has raised environmental concerns due to its significant contributionto global pollution. To address this, researchers have explored incorporating biodegradable polymersinto PE-based blends, using compatibilizers to enhance their properties. This study focused on blendingpoly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) with low-density polyethylene (LDPE) andemployed poly(ethylene-co-glycidyl methacrylate) (EGMA) as a compatibilizer to improve interfacialadhesion. Various blends were prepared, with PHBV content ranging from 0 to 100 wt%, and EGMA wasadded to a 75/25 (LDPE/PHBV) blend at concentrations from 0 to 10 phr. Characterization techniqueslike FTIR spectroscopy, viscosity measurements, and mechanical testing showed that the compatibilizerimproved both the rheological and mechanical properties of the blends, indicating successful interactionbetween the components
Effects on Physical Functioning and Fear of Falling of a 3-Week Balneotherapy Program Alone or Associated with a Physical Activity and Educational Program in Older Adult Fallers: A Randomized-Controlled Trial
No full textInternational audienceBackground: The effects on gait and posture of balneotherapy in fallers are unknown. We assessed the effects on physical functioning and fear of falling of a balneotherapy program alone or combined with a physical activity and educational program in older adult fallers. Methods: A multicenter randomized controlled trial enrolled patients aged 65 or older referred to a 3-week balneotherapy program, and screened for risk of falling (a history of falls in the last year and a timed up and go test or a five chair rising test >12 sec or a 4-meter walk test >4 sec). In addition to balneotherapy, patients had either no intervention (controls) or twelve 60-minute sessions of physical activity including 15 minutes of health education and three 90-minute sessions of an educational program (intervention). Results: There were 118 control and 105 intervention patients. The balneotherapy program alone had a clinically significant effect on (i) the grip strength, (ii) the five chair rising test, (iii) the 4-meter walk test, and (iv) the short physical performance battery (Cohen's d 0.29-0.46). It had no effect on (i) the maximum time stood on one foot, and (ii) the timed up and go test. Furthermore, it worsened the falls efficacy scale (d = 0.27). Adding a physical activity and educational program significantly improved (i) the time stood on one foot (Cohen's d =-0.34), and (ii) the timed up and go test (d=-0.44), (iii) and reduced the concern about falling (Falls Efficacy scale, d=-0.25), and (iv) the fear of falling (d=-0.34).Conclusion: Older patients referred to a balneotherapy program and at high risk of falling when screened at the entrance of the center should be offered an additional physical and educational program to further improve the functional effects of balneotherapy on the timed up and go test, balance, and the fear of falling