Multi-Fluid Simulations of Upper Chromospheric Magnetic Reconnection with Helium-Hydrogen mixture

Our understanding of magnetic reconnection (MR) under chromospheric conditions remains limited. Recent observations have demonstrated the important role of ion-neutral interactions in the dynamics of the chromosphere. Furthermore, the comparison between spectral profiles and synthetic observations of reconnection events suggest that current MHD approaches appear to be inconsistent with observations. First, collisions and multi-thermal aspects of the plasma play a role in these regions. Second, hydrogen and helium ionization effects are relevant to the energy balance of the chromosphere. This work investigates multi-fluid multi-species (MFMS) effects on MR in conditions representative of the upper chromosphere using the multi-fluid Ebysus code. We compare an MFMS approach based on a helium-hydrogen mixture with a two-fluid MHD model based on hydrogen only. The simulations of MRs are performed in a Lundquist number regime high enough to develop plasmoids and instabilities. We study the evolution of the MR and compare the two approaches including the structure of the current sheet and plasmoids, the decoupling of the particles, the evolution of the heating mechanisms, and the composition. The presence of helium species leads to more efficient heating mechanisms than the two-fluid case. This scenario, which is out of reach of the two-fluid or single-fluid models, can reach transition region temperatures starting from upper chromospheric thermodynamic conditions, representative of a quiet Sun scenario. The different dynamics between helium and hydrogen species could lead to chemical fractionation and, under certain conditions, enrichment of helium in the strongest outflows. This could be of significance for recent observations of helium enrichment in the solar wind in switchbacks and CMEs

Field Evaluation with Cognitively-Impaired Older Adults of Attention Management in the Embodied Conversational Agent Louise

International audienceWe present the first experiment we conducted to evaluate the attention monitoring performance of Louise, following a Wizard of Oz method, during the interactions with a cohort of 8 elderly users in a day hospital environment. Louise is a new, semi-automatic prototype of an Embodied Conversational Agent (ECA), a virtual character interacting with users through social-like communication, adapted to the special needs of older adults with cognitive impairment; it is intended to ultimately provide assistance in their activities of daily living. We recorded and analyzed both videos of the conversation-like interactions and Louise's tracking data. In our experiment, Louise's attention estimation algorithm achieved about 80% accuracy; moreover, in almost all cases, the user's attention was successfully recaptured by Louise after a planned, experimenter-induced distraction. These results are in line with what was observed in previous experiments involving only younger adults, thus suggesting that attention measurement tools embedded in cognitive prostheses will not need to be adapted to elderly patients. Finally, to gain further insights on conversation management and provide evidence-based suggestions for future work, we performed an anthropological analysis of the whole experiment

Virtual Promenade: A New Serious Game for the Rehabilitation of Older Adults with Post-fall Syndrome

International audience—We introduce a novel rehabilitation tool to treat Post-Fall Syndrome (PFS) in older adults: a serious game, called Virtual Promenade, combined with a haptic chair imitating the hips movements of human walk. We report on the user-centered design of our prototype, following " living lab " principles, which was well received by our test participants. This system aims at addressing the psycho-motor consequences of older adults' falls; they are often neglected in current post-fall care practices. We first checked for feasibility and tolerability of such interventions. We then applied a living lab participatory design approach, involving health care professionals and older adults, to build the Virtual Promenade prototype. We found that patients with PFS tolerated the system well and that there were no major obstacles to feasibility. We also report that the aesthetics of the virtual environment is an important motivational factor for older adults and discuss our results in searching for the most suitable game controller for this type of patients and game. Finally, we observed that the chairs' movements improved the immersion in the game

Impact of Head Motion on the Assistive Robot Expressiveness - Evaluation with Elderly Persons

International audienceIn the near future, robots will support human to perform tasks in many domains (industrial, domestic, educational and health tasks).Such robot behaviors need to take into account the social interaction between robot and human.In this context, we focus on the expressiveness of a moving head for an assistive robot for the elderly.We designed a new moving head for the Kompaï companion robot.On one hand, this new head improves its perception capabilities.On the other hand, we expect to jointly increase its social skills and thus its acceptability.This new head is composed of a tablet to animate a virtual face according to 4 facial expressions and a mechanical neck with 4 degrees of freedom to enhance the robot's expression.Before improving face expressions and adding more complex head movements, it is essential to evaluate the combination of simple head movements with virtual face expressions. A study was held jointly with physicians (psychologists, ergonomists) at the Broca Hospital in Paris to assess the impact to combine head movements with virtual face expressions, and the global acceptability of the Kompaï head by the elderly

Influence des défauts géométriques sur le comportement des assemblages boulonnés métal-composite

L’utilisation croissante de matériaux composites dans le domaine aéronautique conduit à des assemblages mécaniques métal-composite nécessitant un grand nombre de fixations. A titre d’exemple, l’A380 comporte environ trois millions de fixations dont ¾ de rivets et ¼ de boulons. La contrainte d’interchangeabilité des pièces ainsi que les tolérances serrées usuelles en aéronautique augmentent considérablement le coût et le temps d’assemblage. Peu d’études s’intéressent à l’influence des défauts géométriques sur le comportement des assemblages métal-composite, et ce pour plusieurs raisons. D’une part, la diversité des modes de dégradation du composite (micro-flambage des fibres, décohésion fibre/matrice, rupture des fibres, fissuration de la matrice) induit un comportement fortement non-linéaire du matériau, et donc difficile à modéliser. D’autre part, les essais expérimentaux nécessitent une bonne maîtrise du défaut introduit, tant du point de vue de sa réalisation que de sa mesure. Seul l’effet du jeu dans les assemblages boulonnés a donc fait l’objet de publications. Dans la présente étude on s’intéresse à l’influence du défaut de positionnement des alésages, couplé à celui du jeu, sur des éprouvettes à double-recouvrement aluminium-composite à 2 boulons. On introduit le défaut entre les alésages du composite, de manière à ne plus respecter la coaxialité entre les double-alésages aluminium-composite. Pour compenser cette variation géométrique, le matériau va subir une précontrainte après assemblage. Les transferts de charge entre les boulons en seront donc modifiés en phase de chargement. Les essais expérimentaux et des simulations éléments finis participent au développement d’un modèle analytique adéquat prenant en compte toute la complexité de l’assemblage avec défaut et notamment l’effet de l’endommagement par matage du composite sur les transferts de charge. La réponse aux différents niveaux de jeu et de défaut de positionnement permettra de conclure quant à l’importance des dépassements de tolérance sur la tenue mécanique globale des assemblages boulonnés métal-composite

Anthropometry for children's clothing: difficulties and limitations

Children's wear lacks an anthropometric study to better fit clothes on the body of the child, providing greater comfort for users. Initially, this thesis project in fashion design intended to measure Portuguese children between the ages of 2 to 10 years, enrolled in primary schools in the region of Minho in Portugal. During the data gathering, held in the months of June, July, October and November 2016, about 600 children were scanned and measured using a 3D body scanner. The purpose of this paper is to report the difficulties and limitations experienced during data collection of the anthropometric study and the adjustments that were needed, as well as discuss some of the data collected.This work is supported by FEDER funds through the Competitive Factors Operational Program (COMPETE) POCI-01-0145-FEDER-007136 and by national funds through Portuguese Foundation for Science and Technology (FCT), under the project UID/CTM/000264.info:eu-repo/semantics/publishedVersio

Impact of Head Motion on the Assistive Robot Expressiveness - Evaluation with Elderly Persons

International audienceIn the near future, robots will support human to perform tasks in many domains (industrial, domestic, educational and health tasks).Such robot behaviors need to take into account the social interaction between robot and human.In this context, we focus on the expressiveness of a moving head for an assistive robot for the elderly.We designed a new moving head for the Kompaï companion robot.On one hand, this new head improves its perception capabilities.On the other hand, we expect to jointly increase its social skills and thus its acceptability.This new head is composed of a tablet to animate a virtual face according to 4 facial expressions and a mechanical neck with 4 degrees of freedom to enhance the robot's expression.Before improving face expressions and adding more complex head movements, it is essential to evaluate the combination of simple head movements with virtual face expressions. A study was held jointly with physicians (psychologists, ergonomists) at the Broca Hospital in Paris to assess the impact to combine head movements with virtual face expressions, and the global acceptability of the Kompaï head by the elderly

Campylobacter infection in adult patients with primary antibody deficiency

International audienceNo abstract availabl