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Does the implantation of an uncemented hydroxyapatite-coated first-line stem in a septic environment during a one-stage total hip arthroplasty revision (THAR) for periprosthetic joint infection on total hip arthroplasty provide good results in terms of healing the infection and osteointegration of the stem ?We retrospectively reviewed 40 patients operated on for septic THAR with placement of the cementless Avenir® stem - between 2008 and 2018 at the Besançon University Hospital - with a minimum follow-up of 2 years necessary to define cure in the absence of infectious recurrence. Clinical outcome was assessed using the Harris, Oxford and Merle D'Aubigné scores. Osteointegration was analyzed by the Enhg radiographic score. Mean follow-up was 4.5 years (0-11). Cure of infection was achieved in 35 of 40 (87.5%). The median Harris score was 74/100, Oxford score 45/60, and Merle d'Aubigné score 15/18. Of 37 femoral stems, 36 (97%) had radiographically stable osteointegration. An age of 80 years is a risk factor for failure of septic THAR with implantation of an uncemented stem in one stage.The cementless Avenir® stem has its place in one-stage septic THAR. It gives good results on the healing of the infection and the integration of the stem in the context of femoral bone loss rated Paprosky 1., L’implantation en milieu septique d’une tige de première intention non cimentée recouverte d’hydroxyapatite lors d’une reprise de prothèse totale de hanche (RPTH) infectée en 1 temps opératoire donne-t-elle de bons résultats sur la guérison de l’infection et l’ostéointégration de la tige ?Nous avons examiné rétrospectivement 40 patients opérés d’une RPTH septique avec pose de la tige Avenir® sans ciment - entre 2008 et 2018 au CHRU de Besançon - avec un suivi minimum de 2 ans nécessaire pour définir la guérison en l’absence de récidive infectieuse. Le résultat clinique a été évalué à l'aide des scores de Harris, Oxford et Merle D'Aubigné. L’ostéointégration a été analysé par le score radiographique de Enhg. Le suivi moyen était de 4,5 ans (0-11). La guérison de l’infection a été obtenue chez 35 des 40 (87,5 %). Le score médian de Harris était de 74/100, celui de Oxford de 45/60 et celui de Merle d’Aubigné de 15/18. Sur 37 tiges fémorales, 36 (97 %) avaient une ostéointégration radiographiquement stable. Un âge de 80 ans est un facteur de risque d’échec de la RPTH septique avec implantation d’une tige non cimentée en 1 temps.La tige Avenir® sans ciment a sa place dans la RPTH septique en 1 temps. Elle donne de bons résultats sur la guérison de l’infection et l’intégration de la tige dans le cadre de pertes de substances osseuses fémorales cotées Paprosky 1.

Recent works have explored the potential of machine learning as data-driven turbulence closures for RANS and LES techniques. Beyond these advances, the high expressivity and agility of physics-informed neural networks (PINNs) make them promising candidates for full fluid flow PDE modeling. An important question is whether this new paradigm, exempt from the traditional notion of discretization of the underlying operators very much connected to the flow scales resolution, is capable of sustaining high levels of turbulence characterized by multi-scale features? We investigate the use of PINNs surrogate modeling for turbulent Rayleigh-Bénard (RB) convection flows in rough and smooth rectangular cavities, mainly relying on DNS temperature data from the fluid bulk. We carefully quantify the computational requirements under which the formulation is capable of accurately recovering the flow hidden quantities. We then propose a new padding technique to distribute some of the scattered coordinates-at which PDE residuals are minimized-around the region of labeled data acquisition. We show how it comes to play as a regularization close to the training boundaries which are zones of poor accuracy for standard PINNs and results in a noticeable global accuracy improvement at iso-budget. Finally, we propose for the first time to relax the incompressibility condition in such a way that it drastically benefits the optimization search and results in a much improved convergence of the composite loss function. The RB results obtained at high Rayleigh number Ra = 2 • 10 9 are particularly impressive: the predictive accuracy of the surrogate over the entire half a billion DNS coordinates yields errors for all flow variables ranging between [0.3% − 4%] in the relative L 2 norm, with a training relying only on 1.6% of the DNS data points.

La madera cumple funciones de transporte y almacenamiento de agua, nutrientes y carbohidratos, fundamentales para la sobrevivencia de las especies leñosas frente a variaciones del ambiente. La densidad de la madera, una propiedad emergente de las características anatómicas (proporción de lúmenes y paredes celulares), se relaciona con la capacidad de conducción de agua en el xilema, siendo una variable clave en la arquitectura hidráulica de la planta. Sirve de soporte mecánico y es materia prima para la industria, con lo cual se constituye en una variable de gran valor tecnológico, cobrando relevancia para los procesos de producción, creación, diseño e implementación de productos para el agregado de valor en origen. Se suele afirmar que la densidad permite identificar la calidad de una madera en relación a su uso final: estimar su dureza, porosidad, comportamiento frente a esfuerzos mecánicos, cambios dimensionales, calidad de acabados y rendimiento de distintos procesos industriales, entre otros. Estación Experimental Agropecuaria Bariloche Fil: Martinez Meier, Alejandro. Instituto Nacional de Tecnologia Agropecuaria (INTA). Estacion Experimental Agropecuaria Bariloche. Grupo de Ecologia Forestal; Argentina Fil: Martinez Meier, Alejandro. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Instituto de Investigaciones Forestales y Agropecuarias Bariloche; Argentina Fil: Sergent, Anne Sophie Marie. Instituto Nacional de Tecnologia Agropecuaria (INTA). Estacion Experimental Agropecuaria Bariloche. Grupo de Ecologia Forestal; Argentina Fil: Sergent, Anne Sophie Marie. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Instituto de Investigaciones Forestales y Agropecuarias Bariloche; Argentina Fil: Fernandez, María Elena.Instituto Nacional de Tecnologia Agropecuaria (INTA). Estacion Experimental Agropecuaria Balcarce. Agencia de Extension Rural Tandil; Argentina Fil: Fernandez, María Elena. Consejo Nacional de Investigaciones Cientificas y Tecnicas; Argentina Fil: Dalla Salda, Guillermina. Instituto Nacional de Tecnologia Agropecuaria (INTA). Estacion Experimental Agropecuaria Bariloche. Grupo de Ecologia Forestal; Argentina Fil: Dalla Salda, Guillermina. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Instituto de Investigaciones Forestales y Agropecuarias Bariloche; Argentina Fil: Rozenberg, Philippe. Institut National de la Recherche Agronomique (INRA); Francia Fil: Caballe, Gonzalo. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Bariloche; Argentina Fil: Caballe, Gonzalo. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Instituto de Investigaciones Forestales y Agropecuarias Bariloche; Argentina

Three-dimensional direct numerical simulations are used to characterize turbulent buoy-ant convection in a box-shaped Rayleigh Bénard cavity with a rough bottom plate madeof a series of square based blocks separated by valleys. The cavity is filled with water, andthe Rayleigh number varies over five decades up to 10 10 . As mentioned in the literature,three successive heat transfer regimes are identified: from inactive roughness (I) to aregime (III) where the heat transfer increase is larger than the one expected from theonly roughness induced surface increase. The heat transfers of the transitional regime IIare particularly intense. After validation against experimental and numerical data fromliterature, we highlight the role of the inner fluid trapped within valleys. It is shown thatthe heat transfer through the fluid interface between the cavity bulk and the inner fluidis strongly related to the overall heat transfer at the rough plate, with an exponent ofthe heat transfer scaling law close to 1/2 in the regime II. We found that this regimeis active when the thermal boundary layer is thinner than the roughness height and, atthe same time, the kinetic boundary layer is larger. As compared to regimes I and III,regime II is characterized by larger temperature fluctuations, especially near the roughplate, and a larger friction coefficient. A fluctuating rough layer overlaying both blocksand valleys appears in the regime III, in addition to the classical boundary layers formedalong the plate topography.

Los dendrómetros automáticos de punto son equipos de medición que se usan en la actividad forestal para medir en alta resolución espacial y temporal las variaciones en el fuste de los árboles. Esta información con gran nivel de detalle es relevante para conocer los factores y las condiciones que gobiernan la contracción, la expansión y el crecimiento de los fustes, que ocurren como resultado de balances de contenido hídrico en el tallo y de la división celular del cambium. La variación del clima, la competencia por recursos y la actividad humana pueden incidir en el crecimiento del fuste. Este trabajo plantea la construcción paso a paso de equipos de medición a un costo muy inferior al de los equipos comerciales. Para ello, se lista una serie de elementos componentes y se detalla el procedimiento de armado, las calibraciones realizadas por el grupo de trabajo y las pruebas comparativas con dendrómetros comerciales. Los resultados preliminares muestran que es factible armar dendrómetros a partir de sus partes componentes y que los registros con los equipos desarrollados son similares a los de lo comerciales. Esto permitiría ampliar las posibilidades de fenotipado a gran escala del crecimiento del fuste con un costo significativamente menor al de los equipos disponibles en el mercado. Automatic point dendrometers are measuring equipment used in forestry to measure variations in the stem of trees in high spatial and temporal resolution. This information has a high level of detail and is relevant to assess the factors and conditions governing the contraction, expansion and growth of stems. This is due to balances of water content in the stem and cell division of the cambium. Variations of climate, competition for resources and human activity may influence the growth of the stem. This work proposes the step-by-step construction of a point dendrometer at a lower cost than would imply the acquisition of commercial equipment. For this, a series of component elements is listed, as well as the assembly procedure and calibrations carried out by the workgroup, and the comparative tests with commercial dendrometers. Preliminary results show it is feasible to assemble dendrometers from their component parts and that there is a similarity of records between developed and commercial equipment. This may allow large-scale phenotyping of the stem growth, at a significantly lower cost than acquiring commercial equipment. Fil: Diez, Juan Pablo. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Patagonia Norte. Estación Experimental Agropecuaria San Carlos de Bariloche. Instituto de Investigaciones Forestales y Agropecuarias Bariloche. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones Forestales y Agropecuarias Bariloche; Argentina Fil: de Paz, Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Varela, Santiago Agustín. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Patagonia Norte. Estación Experimental Agropecuaria San Carlos de Bariloche. Instituto de Investigaciones Forestales y Agropecuarias Bariloche. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones Forestales y Agropecuarias Bariloche; Argentina Fil: Dalla Sald, Guillermina Dalla Salda. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Patagonia Norte. Estación Experimental Agropecuaria San Carlos de Bariloche. Instituto de Investigaciones Forestales y Agropecuarias Bariloche. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones Forestales y Agropecuarias Bariloche; Argentina Fil: Sergent, Anne Sophie. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Patagonia Norte. Estación Experimental Agropecuaria San Carlos de Bariloche. Instituto de Investigaciones Forestales y Agropecuarias Bariloche. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones Forestales y Agropecuarias Bariloche; Argentina Fil: Martinez Meier, Alejandro. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Patagonia Norte. Estación Experimental Agropecuaria San Carlos de Bariloche. Instituto de Investigaciones Forestales y Agropecuarias Bariloche. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones Forestales y Agropecuarias Bariloche; Argentina

International audience; We show that, in the case of turbulent Rayleigh–Bénard convection, shadowgraphcan be used to gain quantitative results on the plume statistics and velocity. For thispurpose, we compare the experimental shadowgraph of a Rayleigh–Bénard cell withthe synthetic shadowgraph obtained by calculating the integrated two-dimensionalLaplacian of the temperature field from a numerical simulation very similar to theexperiment. We use image processing tools to enhance the quality of the shadowgraphimage, and obtain quantitative statistics for the thermal plumes, such as plume densityand plume velocity distribution. To highlight the efficiency of this new process ofplume counting, we use, both in the experiment and in the numerical simulation,a turbulent Rayleigh–Bénard convection cell with a rough bottom surface and asmooth top surface, where the statistics of the plumes can be influenced (or not)by the roughness. In addition, the distribution of velocity obtained from processingthe synthetic shadowgraph images of the direct numerical simulations (DNS) or theexperimental shadowgraph images, are compared to the velocity fluid at mid-plane ofthe DNS or particle image velocimetry measurement in the experiment, respectively.It will be shown that the mean velocity profile measured using the advection of theplumes is different from the average Eulerian velocity profile.

La madera cumple funciones de transporte y almacenamiento de agua, nutrientes y carbohidratos, fundamentales para la sobrevivencia de las especies leñosas frente a variaciones del ambiente. La densidad de la madera, una propiedad emergente de las características anatómicas (proporción de lúmenes y paredes celulares), se relaciona con la capacidad de conducción de agua en el xilema, siendo una variable clave en la arquitectura hidráulica de la planta. Sirve de soporte mecánico y es materia prima para la industria, con lo cual se constituye en una variable de gran valor tecnológico, cobrando relevancia para los procesos de producción, creación, diseño e implementación de productos para el agregado de valor en origen. Se suele afirmar que la densidad permite identificar la calidad de una madera en relación a su uso final: estimar su dureza, porosidad, comportamiento frente a esfuerzos mecánicos, cambios dimensionales, calidad de acabados y rendimiento de distintos procesos industriales, entre otros. Estación Experimental Agropecuaria Bariloche Fil: Martinez Meier, Alejandro. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Bariloche. Área de Recursos Forestales. Grupo de Ecología Forestal; Argentina Fil: Sergent, Anne Sophie Marie. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Bariloche. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Instituto de Investigaciones Forestales y Agropecuarias Bariloche; Argentina Fil: Dalla Salda, Guillermina. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Bariloche. Área de Recursos Forestales. Grupo de Ecología Forestal; Argentina Fil: Caballe, Gonzalo. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experiemental Agropecuaria Bariloche. Área de Recursos Forestales. Grupo de Ecología Forestal; Argentina Fil: Rozenberg, Philippe. Institut National de la Recherche Agronomique (INRA); Francia Fil: Fernandez, María Elena. INTA. Estación Experiemental Agropecuaria Balcarce. Agencia de Extensión Rural Tandil. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

International audience

International audience; abstract

International audience; Une caractéristique remarquable de la convection turbulente de Rayleigh-Bénard est l’établissement spontané d’une circulation cohérente à grande échelle remplissant la cavité. Malgré sa simplicité apparente, la convection de Rayleigh-Bénard dans une cellule carr\'e (2D) présente une dynamique à grande échelle riche et complexe où les structures grandes échelles se développant sur des périodesde temps beaucoup plus grandes que les échelles de temps caractéristiques de la turbulence peuvent se renverser, disparaître ou changer d'orientation. A partir de simulations numériques directes des équations de Boussinesq en régime faiblement turbulent (nombres de Rayleigh de $10^5$ à $5 \cdot 10^8$ et un nombre de Prandtl fixé $Pr=3$) et réalisées sur des temps physiques longs (plusieurs milliers d'unités de temps convectives), il est possible d'identifier sur une certaine plage de nombres de Rayleigh, deux régimes intermittents d'écoulement. Le premier régime est caractérisé par des renversements spontanés et souvent consécutifs de la circulation à grande échelle, tandis que le deuxième régime, plus rapide et moins prédominant, est caractérisé par la cessation prolongée de cette circulation. Nous adoptons uneapproche statistique conditionnelle pour étudier les deux régimes séparément, sur plusieurs centaines de renversements observés. Cette approche a permis préalablement de mettre en évidence un cycle générique décrivant énergétiquement les renversements standards en terme d'énergie cinétique et énergie potentielle disponible grâce à une remise à l'échelle temporelle des renversements. Nous reprenons ici cette démarche pour l'appliquer cette fois-ci à l'analyse des structures cohérentes de type POD en nous focalisant sur les six premiers modes. Ceux-ci sont regroupés en plusieurs familles suivant leurs symétries. Tout d'abord, nous nous intéresserons au régime des renversements consécutifs et identifions l'évolution des modes POD durant le cycle générique des renversements standards. Une comparaison de la dynamique temporelle des modes durant les deux régimes (renversements et cessation) est ensuite présentée à partir d'échelles de temps caractéristiques et des diagrammes de phase des coefficients temporels de la POD, mettant en évidence le comportement déterministe des modes pendant le régime de reversements consécutifs, contrairement au caractère plus stochastique du régime de cessations.Enfin, l'énergie relative des modes en fonction du nombre de Rayleigh nous permet de décrire la succession des régimes d'écoulement jusqu'au régime pleinement turbulent.

International audience; We present a DNS study of an air-helium buoyant jet rising in a two vented cavity. Thegeometrical configuration mimics the helium release in an experimental set-up [1] built atCEA Saclay in the framework of security assessment of hydrogen-based systems with anindoor usage. The dimension of the enclosure was chosen to ensure a laminar-turbulenttransition occurring at about the middle height of the cavity.This study aims at determining the relevant computational domain and boundary con-ditions necessary to accurately model the jet development in a vented cavity where themass flow rates crossing the vents are not prescribed. We observe that applying constantpressure outlet boundary conditions directly at the vent interfaces underestimates thevolumetric flow rate of air entering the enclosure and thus overestimates the helium massinside the cavity. On the contrary, adding a surrounding volume into the computationaldomain better predicts the air flow-rate across the vents and leads to a better agreementwith the experimental Particle Image Velocimetry measurements along the vents but alsoinside the cavity.Once the numerical model being set, helium distribution inside the cavity is compared tothe Linden theory [2]. Then the dominant terms of the Turbulent Kinetic Energy equationexpressed in the Reynolds averaged formulation are investigated and in particular thebuoyancy production term.

International audience; We present direct numerical simulations of turbulent buoyant convection over a rough heated plateplaced in a Rayleigh Bénard cell. The roughness is introduced by a set of cubic obstacles regularlyspaced, modelled by using an immersed boundary method. This study aims at clarifying interactionsbetween the large scale circulation filling the box, plume emission and the enhancement of the heattransfer. The simulations are performed in a box-shaped cell at fixed Prandtl number (Pr = 4.38)with the Rayleigh number Ra ranging from 5 à 10 5 to 5 à 10 9 .As expected, results show an enhancement of heat transfer measured by the Nusselt number Nu,depending on the relative sizes of the mean boundary-layer thicknesses and the obstacle height inagreement with previous experimental and numerical studies from the literature (for example [1,2, 3]). By varying Ra, we investigate the successive regimes of the turbulent heat transport, frominactive roughness to a regime where the heat transfer relative increase is larger than the relativesurface increase induced by roughness addition (figure 1). Plume fluctuation dynamics and boundarylayer structure near obstacles will be reported.

International audience

Colloque avec actes et comité de lecture. Internationale.; International audience; This work is devoted to the security assessment of systems using hydrogen as energy carriers, where the problematic is mainly with the hydrogen leakage which is not only dangerous, but can be destructive when mixed with air. The french Atomic Energy Commission (CEA) is showing a great interest to the presented problem and have been participating in several concerned projects that focus on reducing the risks in such systems. We present a numerical Large Eddy Simulation (LES) study to mimic the experiment held at CEA-Saclay, where the above problem is modelled by injecting Helium gas (replacing the Hydrogen in the real problem) through a cylindrical pipe that enters a two-vented parallelepiped cavity filled initially with air. Understanding the mixing/dispersion of the binary fluids at the transient and quasi-steady state is one of the goals that we target on. In spite of the fact that the experiments had been held over a wide range of varied injection flow-rates, we restrict our study to the case of a 5 Nl/min injection resulting in a formation of a buoyant jet that is mainly influenced by momentum in the near source and buoyancy dominant upstream. The dimensions of the cavity had been chosen so that the interesting physical phenomena of the problem is captured; basically the transition from a laminar regime to a turbulent one and the self-similarity of the jet horizontal profiles. In this paper, we present some of our LES results obtained by making use of the CEA code TRUST and the Smagoranski model. We point out basically to the influence of the exterior domain, if it is/isn't considered in the computational domain, on the flow inside the cavity. We demonstrate that imposing classical fixed pressure boundary conditions directly at the vents positions, when compared with the experimental Particle Image Velocitimetry (PIV) measurements, tends to under-estimate the air flow in the cavity and thus leading to over-estimate the maximum Helium concentration. Different simulations had been achieved by varying the size of the exterior domain which is opened from all directions not in contact with the plexi-glass of the cavity. Following a space and a temporal convergence study, our statistical results seems to be satisfactory when compared to the experimental data. This work is a first step as we look on developing new outlet boundary conditions which can be directly applied at the vents positions for a perfect Direct Numerical Simulation (DNS), at the Kolmogorov scales, with a better computational cost.

International audience

International audience; abstract

International audience

International audience