Search results for "Mg"
showing 10 items of 492 documents
Espace de Minkowski-Lorentz et des sphères : un état de l'art
2016
Dans cet article, nous faisons une présentation de l'espace de Minkowski-Lorentz généralisant, à Ê 5 l'espace utilisé dans la théorie de la relativité. Cet espace de dimension 5 contient un paraboloïde de dimension 3 et isométrique à l'espace affine euclidien usuel E 3 , l'ensembles des sphères et plans orientés de E 3 regroupés sur une pseudo-sphère unité de dimension 4. Une premier avantage de cet espace est l'écriture intuitive d'une sphère qui est caractérisée par un point, un vecteur normal en ce point et une courbure. Un deuxième avantage est la manipulation de surfaces canal qui sont représentées par des courbes. Un troisième avantage concernant la simplification des calculs quadrati…
Famille à un paramètre de coniques utilisant des courbes de Bézier à poids complexes
2019
The paper deals with conics in a rational Bézier representation based on mass points where the weights are complex numbers here. A special representation of conics using weighted points and vectors offers a calculus flexibility in the handle elementary geometrical transformations as rotations, homotheties and direct similarity transformations. Some examples are proposed to the reader.
Points massiques, hyperbole et hyperboloïde à une nappe
2015
National audience; Les courbes de Bézier rationnelles quadratiques jouent un rôle fondamental pour la modélisation d'arcs de coniques propre. Cependant, lorsque les deux points extrémaux de l'arc ne sont pas sur la même branche d'une hyperbole, l'utilisation des courbes de Bézier classiques est impossible. Il suffit de considérer les points massiques, à la place des points pondérés, pour remédier à ce problème. De plus, nous gardons la structure (pseudo)-métrique du plan dans lequel nous nous trouvons et il possible de modéliser une branche d'hyperbole dont les extrémités sont deux vecteurs, non colinéaires, de même norme, définis par les directions des asymptotes. Nous donnons comme applic…
The Influence of the feedback control of the hexapod platform of the SAAM dynamic driving simulator on neuromuscular dynamics of the drivers
2012
Multi sensorial cues (visual, auditory, haptic, inertial, vestibular, neuromuscular) [Ang2] play important roles to represent a proper sensation (objectively) and so a perception (subjectively as cognition) in driving simulators. Driving simulator aims at giving the sensation of driving as in a real case. For a similar situation, the driver has to react in the same way as in reality in terms of ‘self motion’. To enable this behavior, the driving simulator must enhance the virtual immersion of the subject in the driving situation. The subject has to perceive the motion of his own body in the virtual scene of the virtual car as he will have in a real car. For that reason, restituting the iner…
Multifunctionality: refocusing a spreading, loose and fashionable concept for looking at sustainability?
2008
International audience; The notion of agriculture's Multifunctionality (MF) emerged in the 1980s. It then followed two trajectories since the 1990s: a conflicting period linked to its use in the international trade negotiations on the one hand, a spreading in terms of meaning, use and geographically on the other hand. Specific meanings appeared in connection with policy making, at national or international levels, or through the involvement of new disciplines. Yet, very few authors discuss the implication of the chosen meaning on their findings. To explore and take advantage of using this word and to deliver it from its controversial use in international trade negotiations, it is absolutely…
Adaptations neuromusculaires des muscles extenseurs du genou : contractions fatigantes uni- vs bi-latérales
2010
The aim of this work was to determine i) the influence of the level of absolute force on the duration of the endurance time, and subsequent neuromuscular alterations in same individual at the end of an exercise performed at the same relative intensity, with one or two legs, ii) the influence of central drive on the force capacity production of the knee extensor muscles during unilateral (UL) vs. bilateral (BL) contractions, iii) activation mechanisms evolution for a serie of submaximal evoked contractions by electrostimulation (EMS). The results of the first study confirm that the endurance limit depends on the level of absolute force for the same individual, contraction duration for UL is …
Trois propositions précaires : Le carrefour, le « vertical settlement » et l’habit comme lieux où les images en migration se côtoient et se façonnent
2019
National audience
Structural and hydrogenation study on the ball milled TiH2–Mg–Ni
2015
International audience; With the aim of further understanding for TieNieMg alloys and their hydrogenation behavior, powders of TiH2, Mg and Ni with the molar ratio of 3:1:2 have been mechanically milled for 10 h, 20 h, 30 h, 40 h according to the stoichiometry (TiH2)1.5Mg0.5Ni. Microstructures of the milled sample were analyzed and their hydrogenation properties as negative electrodes for Ni-MH batteries were studied. Phase change with milling time revealed the fast formation of the Ti-Mg-H FCC phase. The alloying priority among Ti, Mg and Ni was demonstrated by comparing phase compositions in different milling time. Hydrogen capacities evaluated by both solidegas reaction and electrochemic…
Comparison of the generation II with IV heterogeneous Ziegler-Natta catalysts used in propylene polymerizations
1998
An unsupported TiCl3-based catalyst (generation II), modified with n-butyl ether and AlEt2Cl3, was compared with a MgCl2/dibutyl phthalate/AlEt3/cyclohexylmethyldimethoxysilane catalyst system (generation IV) in propylene polymerizations. The latter (magnesium-supported) was fund to be more than 20 times as active as the former and more stereospecific, but to yield PP with a lower molecular weight (Table 2). The kinetics of the polymerizations studied with either of the catalyst, and involving the determination of concentrations of active sites [C0*] and elementary reaction rate constants (Table 4) based on earlier kinetic models, showed the C0*-values in the magnesium-supported catalyst to…
Aktiivisen voimatyyppisen palautumisharjoitteen vaikutus voimantuottoon ja lihasaktiivisuuteen
2010
Riina Flink. 2010. Aktiivisen voimatyyppisen palautumisharjoitteen vaikutus voimantuottoon ja lihasaktiivisuuteen. Kandidaatin tutkielma, Biomekaniikka, Liikuntabiologian laitos, Jyväskylän yliopisto. 52 s. Voimatyyppisen harjoitteen vaikutusta voimaharjoituksesta palautumiseen on tutkittu hyvin vähän. Tämän tutkimuksen tarkoituksena olikin tutkia aktiivisen palautumisjakson vaikutusta raskaasta jalkaprässiharjoituksesta palautumiseen. Aktiivisen palautumisen ryhmä (AP, 5 koehenkilöä) suoritti harjoituksen jälkeen aktiivisen jalkaprässiharjoitteen (10x10) 30% kuormalla alkuperäisestä maksimikuormasta. Passiivisen palautumisen ryhmä (PP, 9 koehenkilöä) taas suoritti passiivisen palautumisjak…