Approche multi-échelle de la mécanique

Les modèles développés en mécanique rationnelle (le formalisme de Lagrange et Hamilton suivi par la méthode géométrique et l'approche par la théorie des groupes, apparues à la suite des révolutions relativiste et quantique) conduisent à des problèmes dont la résolution requiert une approche multi-échelle de la mécanique. Nous construisons une théorie faisant apparaître les modèles comme des projections d'une « structure-mère » qui les génère en en fournissant la raison d'être

Les tenseurs de contraintes électromagnétiques

Dans les dispositifs électromagnétiques, le Tenseur de Maxwell est communément utilisé pour le calcul de la force globale qui s'exerce sur les pièces mobiles comme par exemple le noyau d'un électroaimant ou le rotor d'un moteur électrique. Ce Tenseur est aussi utilisé pour définir les forces de surface qui s'exercent sur les discontinuités matérielles (interfaces et surfaces de matériaux). La littérature mentionne en outre l'existence de plusieurs Tenseurs des contraintes électromagnétiques qui vérifient les mêmes propriétés que celui de Maxwell [1] : les Tenseurs proposés par Minkowski (1908), Einstein & Laud (1908), et, Abraham (1909-10). Ces différentes expressions du Tenseur des contraintes électromagnétiques interrogent sur sa genèse, sa définition et sur sa forme générale. Dans cette communication, nous présentons tout d'abord le Tenseur de Maxwell communément utilisé en génie électrique ainsi que ceux de Minkowski, Einstein & Laud, et, Abraham. Dans un deuxième temps, nous nous intéressons à l'introduction du Tenseur des contraintes électromagnétiques à partir de la force et du couple de volume d'origine électromagnétique. Nous nous basons pour cela sur la 'Pill-box method' et sur le Principe des Puissances Virtuelles appliqué à l'électromagnétisme [1][2]. Nous donnons la forme générale du Tenseur des contraintes électromagnétiques obtenu. Enfin, nous explorons les libertés offertes par cette nouvelle forme pour adopter une expression qui donne une contrainte électromagnétique 'plus douce' que par le Tenseur de Maxwell. Les avantages de ce nouveau Tenseur sont de conduire à un calcul numérique plus précis de la force et du couple globale et, par conséquent, de faciliter le traitement numérique des couplages globaux entre électromagnétisme et mécanique. [1] C. Eringen & G. A. Maugin, Electrodynamics of Continua I et II, Springer-Verlag, 1990. [2] G.A. Maugin, The method of virtual power in continua mechanics: Application to coupled fields, Acta Mechanica 35, (1980)

ESTIMATIVA DE ACERTOS EM TESTE DE PROGRESSO - UMA DAS POSSIBILIDADES DE AVALIAÇÃO DOS ALUNOS

Introdução: O teste de progresso é um método muito utilizado para avaliação da evolução de um acadêmico dentro da faculdade e da qualidade de ensino da mesma, porém ainda restam dúvidas se é possível ter um padrão de desenvolvimento concreto entre alunos de semestres distintos e se isso consegue ser quantificado. Objetivo: Estimar a porcentagem de acertos no Teste de Progresso baseado na etapa que o aluno se encontra em uma faculdade de medicina do estado de São Paulo.Método: Foi feito uma análise de todos os 12 testes de progresso realizados pela instituição desde sua abertura e foi levado em consideração todas as provas de cada etapa, para assim levantar uma análise estatística da taxa de acertos por aluno em determinado semestre, dos 12 semestre do curso de medicina.Resultado: Foi observado um aumento progressivo das notas dos acadêmicos ao longo dos semestres, com acentuada queda da média no 9º semestre, além disso os alunos de diferentes etapas adquiriam notas distintas.Conclusão: O teste de progresso é uma ótima ferramenta de avaliação de desenvolvimento do aluno e da instituição de ensino no geral, porém não tem uma acurácia boa o bastante para servir como padrão-ouro de avaliação, sendo necessários outros métodos de avaliação de metodologia de ensino e desenvolvimento acadêmico para obter resultados mais precisos.Palavras-chave: Teste de Progresso; Educação Médica; Medicina; Universidade.ABSTRACTIntroduction: The progress test is a widely used method for evaluating the evolution of an academic within the faculty and the quality of teaching of the same, but there are still doubts if it is possible to have a concrete pattern of development among students from different semesters and if this can be quantified. Objective: Estimate the percentage of correct answers in the Progress Test based on the stage that the student is in a medical school in the state of São Paulo.Method: An analysis was made of all 12 progress tests carried out by the institution since its opening and all the tests of each stage were taken into account, in order to carry out a statistical analysis of the success rate per student in a given semester, of the 12 semesters of the course. of medicine.Result: A progressive increase in academic grades was observed throughout the semester, with a sharp drop in the average in the 9th semester, in addition, students from different stages acquired different grades.Conclusion: The progress test is a great tool for evaluating the development of the student and the educational institution in general, but it is not accurate enough to serve as the gold standard of evaluation, requiring other methods of evaluation of teaching methodology and academic development to obtain more accurate results.Keywords: Progress Test; Medical Education; Medicine; University.

INTRINSIC AND RELATIONAL PRESENTATION

International audienceHuygens (historical) procedure, which derived impulse from energy by imposing two basic physical requirements – relativity and conservation – is deepened and extended, in order to reveal all possible dynamics compatible with these two requirements. This extension is characterized by its intrinsic nature – viewpoint independent – not requiring any postulation of a specific motion parameter. It reveals, besides the conventional Newtonian and Einsteinian dynamical worlds, other ones, among which those recently proposed in the frameworks of Doubly Special Relativity and Finsler Geometry. Moreover, through an iterative procedure (inspired by what Leibniz called an architectonical approach), this formulation expresses Einsteinian dynamics in a relational way, with an infinity of possible parameters – including the velocity, the rapidity and the celerity, developed in the history of physics by use of analytical methods associated with the variational, group theoretical and geometrical formulations

Dynamics: From analytical principles to architectonical theorems

International audienceA recent article proposed for dynamics a unifying Leibnizian formulation, leading to the quantitative solutions which are usually derived by use of analytical principles (variational, geometrical, dynamical…), each revealing one point of view. Here, we show how to derive not only the solutions but also the formal structures that lead to these solutions. Consequently, with this presentation, the analytical principles, usually postulated separately and independently of one another, appear as theorems

Thermoelastic modeling: application to superresolution in photothermal and thermoelastic microscopy

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Principle of virtual power applied to deformable semiconductors with strain, polarization, and magnetization gradients

International audienceThe aim of this article is to generalize previous works in order to provide a systematic method to derive the equilibrium equations and the constitutive ones for deformable semiconductors accounting for first-order strain, polarization, and magnetization gradients. This is done by use of the “principle of virtual power” subject to the objectivity requirement (i.e., translational and rotational invariances) to which we add the first and the second laws of thermodynamics associated with the conservation of energy and the entropy production. This leads to a generalized expression of the Clausius–Duhem inequality, from which constitutive equations are derived. The interactions of the electromagnetic fields with the deformable and the semiconducting continua appear naturally by generalized non-symmetric stress tensors and the body and surface forces of electromagnetic origin. A comparison with some previous works is made putting emphasis on flexoelectricity that will be dealt with in a future work. Finally, special attention is given to particular cases relative to dissipative phenomena associated with semiconducting properties. In order to be close to what is nowadays done by physicists, the SI units have replaced the Lorentz–Heaviside units often used in previous works

Novel management of ovarian vein thrombosis: A case report

Ovarian vein thrombosis (OVT) is a rare serious diagnosis especially if extending to inferior vein cava (IVC). We present a case of 36-year- old female who was diagnosed with right OVT reaching the inferior vein cava following a supra-cervical hysterectomy that was performed in the postpartum period due to excessive bleeding from uterine fibroids. Using the new generation anti-coagulant “rivaroxaban” for six months followed by maintenance regimen of aspirin and sulodexide, complete resolution of the clot was noticed without any adverse event while using this regimen. This is the first OVT case which is completely treated with rivaroxaban without any adjunct invasive modality. Keywords: Rivaroxaban, Ovarian vein thrombosi