Time-accurate anisotropic mesh adaptation for three-dimensional time-dependent problems with body-fitted moving geometries

International audienceAnisotropic metric-based mesh adaptation has proved its efficiency to reduce the CPU time of steady and unsteady simulations while improving their accuracy. However, its extension to time-dependent problems with body-fitted moving geometries is far from straightforward. This paper establishes a well-founded framework for multiscale mesh adaptation of unsteady problems with moving boundaries. This framework is based on a novel space–time analysis of the interpolation error, within the continuous mesh theory. An optimal metric field, called ALE metric field, is derived, which takes into account the movement of the mesh during the adaptation. Based on this analysis, the global fixed-point adaptation algorithm for time-dependent simulations is extended to moving boundary problems, within the range of body-fitted moving meshes and ALE simulations. Finally, three dimensional adaptive simulations with moving boundaries are presented to validate the proposed approach

Three-dimensional CFD simulations with large displacement of the geometries using a connectivity-change moving mesh approach

This paper deals with three-dimensional (3D) numerical simulations involving 3D moving geometries with large displacements on unstructured meshes. Such simulations are of great value to industry, but remain very time-consuming. A robust moving mesh algorithm coupling an elasticity-like mesh deformation solution and mesh optimizations was proposed in previous works, which removes the need for global remeshing when performing large displacements. The optimizations, and in particular generalized edge/face swapping, preserve the initial quality of the mesh throughout the simulation. We propose to integrate an Arbitrary Lagrangian Eulerian compressible flow solver into this process to demonstrate its capabilities in a full CFD computation context. This solver relies on a local enforcement of the discrete geometric conservation law to preserve the order of accuracy of the time integration. The displacement of the geometries is either imposed, or driven by fluid–structure interaction (FSI). In the latter case, the six degrees of freedom approach for rigid bodies is considered. Finally, several 3D imposed-motion and FSI examples are given to validate the proposed approach, both in academic and industrial configurations

"Brace Technology" Thematic Series - The Lyon approach to the conservative treatment of scoliosis

<p>Abstract</p> <p/> <p>The Lyon Brace, or adjustable multi-shell brace, has been used for more than 60 years.</p> <p>The use and function of the Lyon Brace includes:</p> <p>- The utilization of one or two corrective plaster casts, which enables a true lengthening of the concave ligaments.</p> <p>- An oriented CAD-CAM moulding in 3D auto correction after the removal of the plaster cast.</p> <p>- A blueprint adapted to Lenke's classification.</p> <p>- A specific physiotherapy program.</p> <p>Background</p> <p>Pierre Stagnara created the Lyon Brace in 1947. The brace has the following characteristics:</p> <p>- It adjusts to allow for a child's growth of up to seven centimetres and for an increase in weight of up to seven kilograms.</p> <p>- It is 'active' in that the rigidity of the PMM (polymetacrylate of methyl) structure stimulates the user to auto-correct. The active axial auto-correction decreases the pressures of the brace on the trunk.</p> <p>- It is decompressive in that the effect of extension between the two pelvic and scapular girdles decreases the pressure on the intervertebral disc allowing for more effective pushes in the other planes.</p> <p>- It is symmetrical making it both more aesthetically pleasing and easier to build.</p> <p>- It is stable at both shoulders and pelvic girdle, facilitating the intermediate 3D corrections.</p> <p>- It is transparent. The pressure of the shells on the skin can be directly controlled so "pads" are usually not necessary.</p> <p>Brace description</p> <p>Two metal bars are fixed vertically, one anterior the other posterior and all shells are attached from the bottom to the top in this order:</p> <p>- Two pelvic shells ensure an optimal stability of the brace.</p> <p>- One lumbar shell T12-L4, which can be either independent or extending, at the abdominal chondrocostal level.</p> <p>- One thoracic shell at the level of the thoracic convexity.</p> <p>- One opposite thoracic shell used as a counter push.</p> <p>- One shoulder balance shell on the side of the thoracic convexity.</p> <p>Long term follow up results</p> <p>This is a retrospective study of 1,338 completed treatments checked a minimum of two years after weaning from the brace.</p> <p>Only 5% of the curves progressed more than 5° from the initial magnitudes. This translates to an effectiveness index of 0.95.</p> <p>A subset of 174 subjects who started treatment at Risser 0 was isolated. The global progressive angular mean curve was superimposed on the statistic general curve and the effectiveness index was calculated at 0.80.</p> <p>The Surgery rate was just 2% of the patients presenting with an initial curve below 45°.</p> <p>Conclusion</p> <p>The Lyon Brace is the historical reference of bracing AIS. To be fully effective, it requires the patient to wear a plaster cast for at least one month and receive specific physiotherapy training. Although this is a retrospective study, the results are very positive, and clearly indicate a need for a prospective study.</p

IgG responses to the gSG6-P1 salivary peptide for evaluating human exposure to Anopheles bites in urban areas of Dakar region, Sénégal

<p>Abstract</p> <p>Background</p> <p>Urban malaria can be a serious public health problem in Africa. Human-landing catches of mosquitoes, a standard entomological method to assess human exposure to malaria vector bites, can lack sensitivity in areas where exposure is low. A simple and highly sensitive tool could be a complementary indicator for evaluating malaria exposure in such epidemiological contexts. The human antibody response to the specific <it>Anopheles </it>gSG6-P1 salivary peptide have been described as an adequate tool biomarker for a reliable assessment of human exposure level to <it>Anopheles </it>bites. The aim of this study was to use this biomarker to evaluate the human exposure to <it>Anopheles </it>mosquito bites in urban settings of Dakar (Senegal), one of the largest cities in West Africa, where <it>Anopheles </it>biting rates and malaria transmission are supposed to be low.</p> <p>Methods</p> <p>One cross-sectional study concerning 1,010 (505 households) children (n = 505) and adults (n = 505) living in 16 districts of downtown Dakar and its suburbs was performed from October to December 2008. The IgG responses to gSG6-P1 peptide have been assessed and compared to entomological data obtained in or near the same district.</p> <p>Results</p> <p>Considerable individual variations in anti-gSG6-P1 IgG levels were observed between and within districts. In spite of this individual heterogeneity, the median level of specific IgG and the percentage of immune responders differed significantly between districts. A positive and significant association was observed between the exposure levels to <it>Anopheles gambiae </it>bites, estimated by classical entomological methods, and the median IgG levels or the percentage of immune responders measuring the contact between human populations and <it>Anopheles </it>mosquitoes. Interestingly, immunological parameters seemed to better discriminate the exposure level to <it>Anopheles </it>bites between different exposure groups of districts.</p> <p>Conclusions</p> <p>Specific human IgG responses to gSG6-P1 peptide biomarker represent, at the population and individual levels, a credible new alternative tool to assess accurately the heterogeneity of exposure level to <it>Anopheles </it>bites and malaria risk in low urban transmission areas. The development of such biomarker tool would be particularly relevant for mapping and monitoring malaria risk and for measuring the efficiency of vector control strategies in these specific settings.</p

Diversité des agricultures familiales

Dans un contexte d’interrogation sur les modèles agricoles et de profondes transformations des agricultures et des marchés, cet ouvrage s’attache à revisiter la diversité des formes familiales de production et leurs mutations de par le monde. Dès lors, l’analyse intègre les liens aux marchés, aux territoires et à l’Ailleurs — par le fait migratoire — les enjeux d’autonomie et de sécurité alimentaire, les stratégies de survie et d’accumulation ainsi que les formes d’action collective et politique. L’ouvrage est construit autour de dix-huit études de cas, menées dans les cinq continents. Elles ont toutes été conduites avec un cadre méthodologique, identique et original, inspiré du Sustainable Rural Livehoods (cadre d’identification des moyens de subsistance durables en milieu rural). Revisitée pour cet ouvrage, cette méthode d’observations et d’analyses permet aux auteurs de préciser finement « ce qui fait famille », d’analyser les adaptations du travail des actifs familiaux et les mettre en perspective avec le contexte territorial et les politiques publiques de chaque pays. Écrit à plusieurs mains, par un réseau de chercheurs, cet ouvrage contribue autant à l’approfondissement des savoirs scientifiques sur les agricultures familiales dans le monde qu’à la mise à l’épreuve d’un cadre méthodologique d’analyse et d’observations en milieu rural. Il vise un public de chercheurs, d’enseignants et d’étudiants, agronomes, économistes, sociologues et historiens. Les experts du développement agricole et rural y trouveront un grand intérêt. Plus largement, toute personne qui s’intéresse aux agricultures familiales et à leurs évolutions dans divers contextes sociaux trouvera avantage à cette lecture. Les chercheurs qui ont coordonné cet ouvrage sont agronomes, économistes et géographes, au Cirad ou à l’Inra où ils mènent des recherches sur les systèmes agricoles familiaux à des échelles locales, nationales ou internationales. Cet ouvrage est le fruit d’une démarche de recherche collective et partagée permettant à de nombreux scientifiques des pays du Sud d’exprimer la diversité des réalités agraires contemporaines. Certains coordinateurs ou auteurs de cet ouvrage ont également collaboré à Agricultures familiales et mondes à venir, titre paru en 2014 chez Quae. Ce livre est également disponible en anglais sous le titreDiversity of Family Farming Around the Worldauprès des éditions Springer -www.springer.co

La leucodystrophie métachromatique (à propos d'une fratrie)

DIJON-BU Médecine Pharmacie (212312103) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

Two Mesh Deformation Methods Coupled with a Changing-connectivity Moving Mesh Method for CFD Applications

International audienceThree-dimensional real-life simulations are generally unsteady and involve moving geometries. Industry is currently very far from performing such body-fitted simulations on a daily basis, mainly due to the robustness of the moving mesh algorithm and their extensive computational cost. A moving mesh algorithm coupled to local mesh optimizations has proved its efficiency in dealing with large deformation of the mesh without re-meshing. In this paper, the coupling of this algorithm with two mesh deformation techniques is studied: an elasticity PDE-based one and an explicit Inverse Distance Weighted interpolation one, and both techniques are compared. The efficiency of this method is demonstrated on challenging test cases, involving large body deformations, boundary layers and large displacements with shearing. Finally, the moving mesh algorithm is coupled to a CFD flow solver

L'occupation du sol au Second âge du Fer dans le massif jurassien : bilan et perspectives

International audienc