Sélection et étalonnage des mouvements sismiques pour les études de sécurité des barrages-poids situés dans l'Est du Canada

RÉSUMÉ Selon la loi sur la sécurité des barrages du Québec, il est permis d’utiliser les données de la commission géologique du Canada (CGC) pour définir l’aléa sismique susceptible d’affecter la réponse sismique des ouvrages. Les données de la CGC sont reprises par le code national du bâtiment du Canada (CNB). L’annexe J du CNB donne les principales lignes directrices quant à la sélection et l’étalonnage des sollicitations sismiques à utiliser pour les analyses dynamiques. Le CNB est développé pour les bâtiments qui possèdent, le plus souvent, des caractéristiques dynamiques différentes de celles des barrages en béton qui ont de courtes périodes de vibration.----------ABSTRACT According to the Quebec dam safety legislation, it is allowed to use the data from the geological survey of Canada (GSC) to define the seismic hazard likely to affect the seismic response of structures. The GSC data are used by the national building code of Canada (NBCC). Appendix J of the NBCC gives the main guidelines as for selection and scaling of ground motions to use in dynamic analyses. The NBCC is developed for buildings that have most often dynamic characteristics different from those of the concrete dams which have short periods of vibration

ACUTE EFFECTS OF TECHNICAL INSTRUCTIONS ON SPRINT ACCELERATION TECHNIQUE AND PERFORMANCE

This study investigated the acute effect of verbal technical instructions intended to alter attentional focus during a 10 m sprint. Team sports athletes (n = 15) completed maximal effort sprints under a control condition and two experimental conditions: internal and external focus. Lower-body kinematic and external kinetic data were collected near the 5 m mark. Total sprint time was longer in both experimental conditions than the control condition (p < 0.05). Both experimental conditions altered ankle and knee angles at touchdown and led to more vertically oriented ground reaction forces (all p < 0.05). Whilst these instructions were detrimental to performance, the results support the importance of technical ability for sprint acceleration. Future studies should seek to identify instructions, potentially used within training programmes, which could be beneficial to performance

Alterations to the orientation of the ground reaction force vector affect sprint acceleration performance in team sports athletes

A more horizontally oriented ground reaction force vector is related to higher levels of sprint acceleration performance across a range of athletes. However, the effects of acute experimental alterations to the force vector orientation within athletes are unknown. Fifteen male team sports athletes completed maximal effort 10-m accelerations in three conditions following different verbal instructions intended to manipulate the force vector orientation. Ground reaction forces (GRFs) were collected from the step nearest 5-m and stance leg kinematics at touchdown were also analysed to understand specific kinematic features of touchdown technique which may influence the consequent force vector orientation. Magnitude-based inferences were used to compare findings between conditions. There was a likely more horizontally oriented ground reaction force vector and a likely lower peak vertical force in the control condition compared with the experimental conditions. 10-m sprint time was very likely quickest in the control condition which confirmed the importance of force vector orientation for acceleration performance on a within-athlete basis. The stance leg kinematics revealed that a more horizontally oriented force vector during stance was preceded at touchdown by a likely more dorsiflexed ankle, a likely more flexed knee, and a possibly or likely greater hip extension velocity

Chloridobis(dimethyl­glyoximato-κ2 N,N′)(ethyl pyridine-3-carboxyl­ate-κN)cobalt(III)

In the title compound, [Co(C4H7N2O2)2Cl(C8H9NO2)], which was prepared as a model complex of vitamin B12, the CoIII atom, which is linked to four N atoms of the pseudo-macrocyclic (dmgH)2 ligand (dmgH is dimethyl­glyoximate) in the equatorial plane and one Cl− anion and one N atom of ethyl nicotinate in apical positions, displays an approximately octa­hedral coordination. The Co atom is 0.0187 (8) Å out of the mean plane of the four equatorial N atoms. The structure has an O⋯H⋯O bridge, which is very common in cobaloxime derivatives, with O⋯H distances of 1.24 (2) and 1.25 (2) Å

Chloridobis(dimethyl­glyoximato-κ2 N,N′)(ethyl pyridine-4-carboxyl­ate-κN)cobalt(III) chloro­form monosolvate

The title compound, [Co(C4H7N2O2)2Cl(C8H9NO2)]·CHCl3, was synthesized as a model complex of vitamin B12. The CoIII cation displays an approximately octa­hedral coordination environment, being displaced by 0.0240 (15) Å from the mean plane of the four N atoms of the equatorial plane. The O—H distances in the dimethyl­glyoximate hy­droxy groups are 0.89 (6) and 1.14 (6) Å; such long O—H bonds are very common in cobaloxime derivatives. Weak classical O—H⋯N and non-classical C—H⋯Cl hydrogen-bonding interactions further consolidate the crystal packing