3 research outputs found
On the determination of cusp points of 3-R\underline{P}R parallel manipulators
This paper investigates the cuspidal configurations of 3-RPR parallel
manipulators that may appear on their singular surfaces in the joint space.
Cusp points play an important role in the kinematic behavior of parallel
manipulators since they make possible a non-singular change of assembly mode.
In previous works, the cusp points were calculated in sections of the joint
space by solving a 24th-degree polynomial without any proof that this
polynomial was the only one that gives all solutions. The purpose of this study
is to propose a rigorous methodology to determine the cusp points of
3-R\underline{P}R manipulators and to certify that all cusp points are found.
This methodology uses the notion of discriminant varieties and resorts to
Gr\"obner bases for the solutions of systems of equations
Les francophones face Ă leur langue
Cette contribution tente de porter au jour certains aspects, au plan des reprĂ©sentations, du paysage linguistique de la RĂ©publique du Niger qui connaĂźt une situation de diglossie vĂ©hiculaire opposant le français, variĂ©tĂ© « haute », au hausa et zarma, variĂ©tĂ©s « basses ». Dâune enquĂȘte fondĂ©e sur un Ă©chantillon de plus de 3 800 rĂ©pondants appartenant Ă lâune des cinq communautĂ©s linguistiques dominantes, des indicateurs ont Ă©tĂ© dĂ©gagĂ©s afin de cerner lâimage que les NigĂ©riens se font du français, unique langue officielle Ă cĂŽtĂ© dâune sĂ©rie de langues locales au poids trĂšs variable. Pays officiellement francophone, peu visitĂ© par les spĂ©cialistes, le Niger trouve ici lâun des premiers comptes rendus Ă portĂ©e gĂ©nĂ©rale concernant sa rĂ©alitĂ© sociolinguistique.The French-Speaking Peoples and their Languages: The Case of the Nigeriens. â Among the attitudes domain, this paper attempts to bring some features of the linguistic landscape of the Niger Republic to light, characterized by a situation of vehicular diglossy opposing French, âhighâ variety, to Hausa and Zarma, âlowâ varieties. From an enquiry based on a sample of more than 3,800 individuals, all of them belonging to one of the five major linguistic communities, indicators were selected in order to understand the Nigeriensâ linguistic image about French, one and only official language, next to several local languages which importance varies a lot. Officially French-speaking country and not so studied by specialists, Niger finds here one of first wide-ranged reports about the national sociolinguistic reality
Langues déliées
La linguistique se suffit Ă elle-mĂȘme? Cette perspective autocentrĂ©e, faisant du langage un tout en soi, indĂ©pendant et homogĂšne, est ici contestĂ©e. Bien au contraire, le langage se situe au carrefour d'une multiplicitĂ© de positionnements humains qui le constituent, le dĂ©multiplient, le font Ă©voluer et se transformer. L'analyse des situations africaines, Ă travers les pratiques et les discours sur les pratiques, nous amĂšne Ă concevoir les «langues» dans leur constitution plurielle et mouvant..