Un illusoire consensus ? La densité politique de la Coupe du monde de football en Amérique latine

L’année 2014 a été chargée au plan politique et sportif en Amérique latine. Parmi les neuf pays de la région qualifiés pour la Coupe du monde masculine de football, qui s’est déroulée du 12 juin au 13 juillet 2014 au Brésil, quatre ont tenu la même année des élections générales : le Costa Rica (février), la Colombie (mai-juin), le Brésil (octobre) et l’Uruguay (octobre). La convergence des calendriers a été particulièrement marquante en Colombie, où le second tour de l’élection présidentielle s’est joué le 15 juin, le lendemain de la victoire de la sélection nationale contre la Grèce. Si aucune étude d’analyse électorale n’a pu, à notre connaissance, prouver une corrélation réelle entre les résultats des équipes nationales de football et les comportements électoraux (vote-sanction en cas de défaite ou vote de reconnaissance en cas de succès), les enjeux politiques du football n’en sont pas moins importants et repérables à différents niveaux. Ils se manifestent avec une vigueur et une visibilité accrues à l’approche d’un événement aussi populaire et médiatisé qu’une Coupe du monde..

The use of thermally expandable microcapsules for increasing the toughness and heal structural adhesives

In this research, the effect of thermally expandable microcapsules (TEMs) on mode I fracture toughness of structural adhesives were investigated. The single-edge-notch bending (SENB) test was used. Firstly, a standard toughness test was performed on adhesives with microcapsules. Secondly, since TEMs start their expansion at approximately 60ºC, the next specimens were fatigue tested expecting a local heating in the notch leading to the desired expansion before being statically loaded for fracture toughness determination. Thirdly, a manual local heating at 90ºC was applied in the notch before the fracture static test. The experimental results were successfully cross-checked through a numerical analysis using the virtual crack closure technique (VCCT) based on linear elastic fracture mechanics (LEFM). The major conclusion is that fracture toughness of the modified adhesives increased as the mass fraction of the TEMs increased

Elimination-based certificates for triangular equivalence and rank profiles

International audienceIn this paper, we give novel certificates for triangular equivalence and rank profiles. These certificates enable somebody to verify the row or column rank profiles or the whole rank profile matrix faster than recomputing them, with a negligible overall overhead. We first provide quadratic time and space non-interactive certificates saving the logarithmic factors of previously known ones. Then we propose interactive certificates for the same problems whose Monte Carlo verification complexity requires a small constant number of matrix-vector multiplications, a linear space, and a linear number of extra field operations, with a linear number of interactions. As an application we also give an interactive protocol, certifying the determinant or the signature of dense matrices, faster for the Prover than the best previously known one. Finally we give linear space and constant round certificates for the row or column rank profiles

The use of thermally expandable microcapsules for increasing the toughness and heal structural adhesives

In this research, the effect of thermally expandable microcapsules (TEMs) on mode I fracture toughness of structural adhesives were investigated. The single-edge-notch bending (SENB) test was used. Firstly, a standard toughness test was performed on adhesives with microcapsules. Secondly, since TEMs start their expansion at approximately 60ºC, the next specimens were fatigue tested expecting a local heating in the notch leading to the desired expansion before being statically loaded for fracture toughness determination. Thirdly, a manual local heating at 90ºC was applied in the notch before the fracture static test. The experimental results were successfully cross-checked through a numerical analysis using the virtual crack closure technique (VCCT) based on linear elastic fracture mechanics (LEFM). The major conclusion is that fracture toughness of the modified adhesives increased as the mass fraction of the TEMs increased

Parameterized cellular material for the elastic mimetization of cancellous bone

Bone tissue mechanical properties and trabecular microarchitecture are the main factors that determine the biomechanical properties of cancellous bone. Artificial cancellous microstructures, typically described by a reduced number of geometrical parameters, can be designed to obtain a mechanical behavior mimicking that of natural bone. In this work, we assess the ability of the parameterized microstructure introduced by Kowalczyk (P. Kowalczyk, Comput Meth Biomech Biomed Eng, 9:135–147, 2006) to mimic the elastic response of cancellous bone. An optimization approach is devised to find the geometrical parameters of the artificial microstructure that better mimics the elastic response of target natural bone specimen. This is done via a Pattern Search algorithm that minimizes the difference between the symmetry class decompositions of the elastic tensors. The performance of the method is demonstrated via analyses for 146 bone samples.Publicado en: Mecánica Computacional vol. XXXV, no. 8.Facultad de Ingenierí

Parameterized cellular material for the elastic mimetization of cancellous bone

Bone tissue mechanical properties and trabecular microarchitecture are the main factors that determine the biomechanical properties of cancellous bone. Artificial cancellous microstructures, typically described by a reduced number of geometrical parameters, can be designed to obtain a mechanical behavior mimicking that of natural bone. In this work, we assess the ability of the parameterized microstructure introduced by Kowalczyk (P. Kowalczyk, Comput Meth Biomech Biomed Eng, 9:135–147, 2006) to mimic the elastic response of cancellous bone. An optimization approach is devised to find the geometrical parameters of the artificial microstructure that better mimics the elastic response of target natural bone specimen. This is done via a Pattern Search algorithm that minimizes the difference between the symmetry class decompositions of the elastic tensors. The performance of the method is demonstrated via analyses for 146 bone samples.Publicado en: Mecánica Computacional vol. XXXV, no. 8.Facultad de Ingenierí