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Particle size-dependent viscoelastic Fe(II)-triazole composites in the low-spin state
No full textInternational audienceA series of soft spin crossover (SCO) [Fe(Htrz)2(trz)](BF4)/NaPSS composites have been prepared by dispersing rod-shaped particles of different lengths (32 nm, 65 nm, 474 nm and 1.2 μm) in a concentrated sodium polystyrene sulfonate (NaPSS) aqueous solution. The magnetic investigation revealed hysteretic behaviour and significant widening of the hysteresis loop for all particle sizes, compared to the pristine particles, resulting essentially from the shift of the HS-to-LS transition temperature (T↓1/2) towards lower temperatures, attributed to the negative pressure effect exerted by the NaPSS polymer on the HS-to-LS transition of the particles. The rheological study of the composites, performed in the linear viscoelastic domain over a large time scale, revealed a critical gel like behaviour, indicative of scale-invariant relaxation behaviour. The strength of the gel increases as the particle size decreases or as the concentration increases, without changing the structural parameters, making it possible to tune the viscoelastic properties of the composites
The acceptability of sufficiency practices in food consumption among consumers
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Two-Phase Peridynamic Elasticity with Exponential Kernels: I. Statics and Vibrations of Axial Rods
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Sediment Transfer Along Pénestin Peninsula Coastline: Insights from Photogrammetric Analysis and Integrated Littoral Monitoring
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Mechanisms of transverse cracking induced by adjacent ply matrix cracks in composite laminates
No full textInternational audienceCracking in composite laminates containing θ-plies adjacent to 90 deg. plies is studied experimentally and numerically using the coupled criterion. Experimental observations of the composite edge evidence θ-ply cracking i) at an imposed strain level much larger than first transverse cracking in 90 deg. ply for a sufficiently large orientation mismatch between adjacent plies or ii) at a similar imposed strain level if the mismatch angle between two adjacent plies is small. The latter phenomenon may be mitigated by the presence of a 0 deg. ply between the 90 deg. and the θ-plies. These conclusions are supported by numerical simulation of the experimentally observed damage mechanisms, which also highlight that debonding between adjacent plies may occur as it becomes more favorable that adjacent ply crack re-initiation for sufficiently large adjacent ply mismatch angle.Cracking in composite laminates containing θ-plies adjacent to 90°plies is studied experimentally and numerically using the coupled criterion and finite element calculations. Different damage mechanisms are considered, namely transverse cracking in 90°, cracking in θ-plies, or debonding between adjacent misoriented plies. The influence of the stacking sequence on the damage mechanism sequence is investigated. Experimental observations of the composite edge under tensile loading evidence θ-ply cracking (i) at an imposed strain level much larger than first transverse cracking in 90°ply for a sufficiently large orientation mismatch between adjacent plies or (ii) at a similar imposed strain level if the mismatch angle between two adjacent plies is small. The latter phenomenon may be mitigated by the presence of a 0°ply between the 90°a nd the θ-plies.These conclusions are supported by numerical simulation of the experimentally observed damage mechanisms, evidencing a change in the damage mechanism sequence depending on the θ-ply misorientation. The numerical simulations also highlight that debonding between adjacent plies may occur as it becomes more favorable that adjacent ply crack re-initiation for sufficiently large adjacent ply mismatch angle.Résumé. La fissuration dans les stratifiés composites, contenant des plis orientés à θ°de la direction de chargement adjacents à des plis à 90°, est étudiée expérimentalement et numériquement à l'aide du critère couplé et de calculs par éléments finis. Différents mécanismes d'endommagement sont pris en compte : la fissuration transverse dans le pli à 90°, la fissuration dans les plis à θ°, ou la décohésion entre des plis adjacents d'orientation différente. L'influence de la séquence d'empilement sur la séquence des mécanismes d'endommagement est analysée. Les observations expérimentales effectuées sur des stratifiés sollicités en traction mettent en évidence une fissuration dans les plis à θ : (i) à un niveau de déformation imposé beaucoup plus élevé que celui de la première fissuration transverse dans les plis à 90°pour une désorientation suffisamment grand entre les plis adjacents, ou (ii) à un niveau de déformation imposé similaire si l'angle de</div
Accurate Cerebral Venous Blood Flow Simulations Compared to Real Data
No full textInternational audienceIn this work, we develop models of cerebral venous blood flows in realistic 3D geometries and run accurate numerical 3D simulations leveraging real data. These data come from Magnetic Resonance Imaging measures and provide both morphological and physiological information on the same subject. It allows to calibrate a subject specific simulation and improve its reliability. We present the complete pipeline going from data pre-processing to the integration in the simulation framework. The 3D Finite Element simulations in the main cerebral venous vessels are coupled with Windkessel reduced models, whose parameters are chosen according to the data, to take into account the neglected network. First results are discussed and compared with literature data, opening the way to obtain reliable information difficult or even impossible to obtain in vivo in a non-invasive way. All codes are in-house openly developed ones to ensure reproducibility
Des nombres de Cantor et de Dedekind aux nombres de Conway - Partie 0: Nombres ordinaux, nombres rationnels et nombres entiers
No full textCet exposé d'histoire des mathématiques, en deux parties, est une motivation et une présentation du Chapitre 0 de la partie 0 (pages 2 à 14) du livre de John Conway "On Numbers and Games" (1976, 2ème édition 2000).Nous partirons de la construction des nombres ordinaux de Georg Cantor (1895) donnée par Paul R. Halmos (1965) -- à la suite de John Von Neumann (1923) -- et de la construction des nombres réels par Edmund Landau (1927) -- à la suite de Richard Dedekink (1887) -- et présenterons leur généralisation par John Conway (1976)