Analyse thermomécanique des lois de comportement par thermographie infrarouge

The knowledge of dissipative and non dissipative phenomena associated to quasi-static déformation processes, is a fundamental supplementary asset for determination of thermomechanical behaviour law. On depicts, in this paper, an experimental set-up, using infra-red technics, which allows to observe thermal and energetical phenomena during sample déformation. After restating the definition of the energy balance, in case of elastic-plastic materials, the relationship between the dissipation (or the stored energy of cold working) and the hardening state variables are recalled. The dissipation is continuously evaluated during monotonic tensile test. Numerized maps of surface temperature are used. The experimental arrangement is described ; then the physical model, which allows to relate the dissipation to the temperature signals, and the calibration method are successively introduced. Results on several materials are shown and their incidence on the behaviour law is succinctly mentioned.La connaissance des phénomènes dissipatifs et non dissipatifs associés aux processus quasi-statiques de déformation, représente un atout supplémentaire important pour l'élaboration de loi thermomécanique de comportement. On décrit, ici, un dispositif expérimental, utilisant les techniques de thermographie infrarouge, et permettant d'observer les phénomènes thermiques et énergétiques durant la déformation d'un échantillon en traction simple. Après avoir rappelé la définition du bilan énergatique, dans le cas de matériaux élasto-plastiques, on relie la dissipation et l'énergie interne bloquée durant l'écrouissage, aux variables d'état. La puissance mécanique dissipée est évaluée continûment durant l'essai. On utilise pour cela, les images thermiques fournies par la caméra infra-rouge. On présente le dispositif expérimental, puis successivement, on décrit le modèle physique permettant de relier l'énergie dissipée aux cartes de température de surface ainsi que le protocole d'étalonnage. En fin d'article, on présente quelques résultats obtenus avec plusieurs matériaux et on évoque rapidement leur incidence sur la forme des lois de comportement

Circulating adrenomedullin estimates survival and reversibility of organ failure in sepsis: the prospective observational multinational Adrenomedullin and Outcome in Sepsis and Septic Shock-1 (AdrenOSS-1) study

Background: Adrenomedullin (ADM) regulates vascular tone and endothelial permeability during sepsis. Levels of circulating biologically active ADM (bio-ADM) show an inverse relationship with blood pressure and a direct relationship with vasopressor requirement. In the present prospective observational multinational Adrenomedullin and Outcome in Sepsis and Septic Shock 1 (, AdrenOSS-1) study, we assessed relationships between circulating bio-ADM during the initial intensive care unit (ICU) stay and short-term outcome in order to eventually design a biomarker-guided randomized controlled trial. Methods: AdrenOSS-1 was a prospective observational multinational study. The primary outcome was 28-day mortality. Secondary outcomes included organ failure as defined by Sequential Organ Failure Assessment (SOFA) score, organ support with focus on vasopressor/inotropic use, and need for renal replacement therapy. AdrenOSS-1 included 583 patients admitted to the ICU with sepsis or septic shock. Results: Circulating bio-ADM levels were measured upon admission and at day 2. Median bio-ADM concentration upon admission was 80.5 pg/ml [IQR 41.5-148.1 pg/ml]. Initial SOFA score was 7 [IQR 5-10], and 28-day mortality was 22%. We found marked associations between bio-ADM upon admission and 28-day mortality (unadjusted standardized HR 2.3 [CI 1.9-2.9]; adjusted HR 1.6 [CI 1.1-2.5]) and between bio-ADM levels and SOFA score (p < 0.0001). Need of vasopressor/inotrope, renal replacement therapy, and positive fluid balance were more prevalent in patients with a bio-ADM > 70 pg/ml upon admission than in those with bio-ADM ≤ 70 pg/ml. In patients with bio-ADM > 70 pg/ml upon admission, decrease in bio-ADM below 70 pg/ml at day 2 was associated with recovery of organ function at day 7 and better 28-day outcome (9.5% mortality). By contrast, persistently elevated bio-ADM at day 2 was associated with prolonged organ dysfunction and high 28-day mortality (38.1% mortality, HR 4.9, 95% CI 2.5-9.8). Conclusions: AdrenOSS-1 shows that early levels and rapid changes in bio-ADM estimate short-term outcome in sepsis and septic shock. These data are the backbone of the design of the biomarker-guided AdrenOSS-2 trial. Trial registration: ClinicalTrials.gov, NCT02393781. Registered on March 19, 2015

Gender-specific association of body composition with inflammatory and adipose-related markers in healthy elderly Europeans from the NU-AGE study

Objectives: The aim of this work was to examine the cross-sectional relationship between body composition (BC) markers for adipose and lean tissue and bone mass, and a wide range of specific inflammatory and adipose-related markers in healthy elderly Europeans. Methods: A whole-body dual-energy X-ray absorptiometry (DXA) scan was made in 1121 healthy (65–79 years) women and men from five European countries of the “New dietary strategies addressing the specific needs of elderly population for a healthy aging in Europe” project (NCT01754012) cohort to measure markers of adipose and lean tissue and bone mass. Pro-inflammatory (IL-6, IL-6Rα, TNF-α, TNF-R1, TNF-R2, pentraxin 3, CRP, alpha-1-acid glycoprotein, albumin) and anti-inflammatory (IL-10, TGF-β1) molecules as well as adipose-related markers such as leptin, adiponectin, ghrelin, and resistin were measured by magnetic bead-based multiplex-specific immunoassays and biochemical assays. Results: BC characteristics were different in elderly women and men, and more favorable BC markers were associated with a better adipose-related inflammatory profile, with the exception of skeletal muscle mass index. No correlation was found with the body composition markers and circulating levels of some standard pro- and anti-inflammatory markers like IL-6, pentraxin 3, IL-10, TGF-β1, TNF-α, IL-6Rα, glycoprotein 130, TNF-α-R1, and TNF-α-R2. Conclusions: The association between BC and inflammatory and adipose-related biomarkers is crucial in decoding aging and pathophysiological processes, such as sarcopenia. DXA can help in understanding how the measurement of fat and muscle is important, making the way from research to clinical practice. Key Points: • Body composition markers concordantly associated positively or negatively with adipose-related and inflammatory markers, with the exception of skeletal muscle mass index. • No correlation was found with the body composition markers and circulating levels of some standard pro- and anti-inflammatory markers like IL-6, pentraxin 3, IL-10, TGF-β1, TNF-α, IL-6Rα, gp130, TNF-α-R1, and TNF-α-R2. • Skeletal muscle mass index (SMI) shows a good correlation with inflammatory profile in age-related sarcopenia

Constrained modifications of non-manifold b-rep models

International audienceNon manifold boundary representations (b-reps) are increasinglyused in Geosciences for a variety of applications (3D geographicalinformation systems, basin modeling, geophysical processing,etc.). Meanwhile, the uncertainties associated with subsurface datamake it desirable to modify such models efficiently. We presenta method to deform locally a surface in a triangulated b-rep whilemaintaining a constant number of spatial regions in the model. Thisrequires that the reshaped surface does not intersect the boundariesof its adjoining regions, which can be checked using existing collisiondetection algorithms. Besides, the non-manifold contacts mustbe updated after the modification, and the triangles must be altered,to maintain sealed regions. For this, we propose to parameterizelocally the surfaces that the modified surface moves along. Thisparametric space is used to 1) constrain the displacement of the deformedsurface border and, 2) re-triangulate in the plane the neighboringsurfaces around the modified contacts. The method, tested inthe context of an interactive graphical manipulator, is very efficientand independent from the deformation mechanism

Constrained modifications of non-manifold b-rep models

International audienceNon manifold boundary representations (b-reps) are increasinglyused in Geosciences for a variety of applications (3D geographicalinformation systems, basin modeling, geophysical processing,etc.). Meanwhile, the uncertainties associated with subsurface datamake it desirable to modify such models efficiently. We presenta method to deform locally a surface in a triangulated b-rep whilemaintaining a constant number of spatial regions in the model. Thisrequires that the reshaped surface does not intersect the boundariesof its adjoining regions, which can be checked using existing collisiondetection algorithms. Besides, the non-manifold contacts mustbe updated after the modification, and the triangles must be altered,to maintain sealed regions. For this, we propose to parameterizelocally the surfaces that the modified surface moves along. Thisparametric space is used to 1) constrain the displacement of the deformedsurface border and, 2) re-triangulate in the plane the neighboringsurfaces around the modified contacts. The method, tested inthe context of an interactive graphical manipulator, is very efficientand independent from the deformation mechanism

Plastic and dissipated work and stored energy

International audienceThis paper depicts one theoretical and experimental method to take into account the energy phenomena, associated with the elasto—plastic deformation process, during the elaboration of behaviour laws. The energy balance definition is examined in order to relate the stored energy of cold work to the hardening state variables. Two experimental approaches are used to study the evolution of the energy balance. The first one uses microcalorimetric technique and the second infrared technique. Several industrial metallic materials are studied by both approaches. Energy data are used to control the validity domain of the classical behaviour laws and to elaborate new more appropriate ones. Therefore, the hardening parameters cannot be identified with the thermodynamical forces. The use of energy considerations allows the definition of new thermodynamical forces and state variables, in the case of isotropic or kinematical hardening

Defining Proper Boundary Conditions in 3-D Structural Restoration: A Case Study Restoring a 3-D Forward Model of Suprasalt Extensional Structures

International audienceTo overcome the non-physical limitations to 2D structural restoration tools, efforts are being made toward developing 3D mechanics-based methods, which respect both mass and linear momentum conservations. 3D methods remove many common assumptions in 2D techniques that are often violated in nature, such as line-length and area conservation or constant boundary condition (BC) displacement. However, 3D restorations have challenges of their own that must be overcome to produce accurate, physical representations of rock deformation. One of the greatest challenges is choosing geologically and physically reasonable BCs. These are often based on accepted geometric assumptions, such as flattening and unfolding a datum horizon while simultaneously removing fault offset. However, these BCs, as based on kinematic hypotheses, may lead to unphysical configurations. In addition, non-physical BCs are often required in order to ensure numerical convergence (e.g. fixing degrees of freedom), adding uncertainty to the result. Understanding the forward deformation process is crucial for defining proper BCs and accurate interpretations of a restoration. In this study, we perform a 3D restoration on the structures formed from a 3D analog model. Restoring a forward model provides a priori knowledge of viable BCs to guide our restorations without adding unknown uncertainty to the result. The analog experiment was a 3D forward model of a gravity-driven extensional system with sand layers above a ductile zone, no pre-existing fault architecture and a 1.5° basinward dip. Sedimentary layers were added as growth strata throughout the forward model, recording the timing and kinematics of fault activity and fold growth. The analog model produced two prominent grabens, several half-grabens, salt welds and secondary fault structures. Using BCs defined from knowledge of the undeformed and deformed states, we perform a sequential 3D restoration of this extensional system. These BCs at each time-step are constrained by video capturing the complete forward deformation sequence. These findings are the first to document how accurate BCs add value to 3D restoration techniques. Moreover, restoring the complex structures in our model provides fundamental insight into the temporal evolution of 3D extensional structures, akin to natural suprasalt basins like GOM, Brazil and Angola. This clears the path for increasing accuracy in strain evaluation and assessment of paleo-basin geometry