Journal of Gender Equality Disability Social Inclusion and Children
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Modèle économétrique de la production bovine; Annexe III
No full textDiffusion du document : Station d'Economie et Sociologie rurales 65 rue de Saint-Brieuc 35042 RENNES CEDEX (FRA)L'analyse de la production bovine suggère l'existence de concepts que l'on s'est efforcé de relier les uns aux autres de manière à construire un ensemble théorique cohérent. Toutefois, et pour tenir compte de la complexité du réel, il est apparu nécessaire de procéder par étapes, d'étoffer peu à peu la construction initiale, autrement dit d'introduire progressivement des variables "de manière à rester maître de l'explication"
Coupe stratigraphique du synclinal de Martigne Ferchaud
No full textLe but essentiel de notre travail effectué pendant les vacances dePâques 1961, a été l'étude des formations ordoviciennes et siluriennesqui constituent le synolinorium de Martigné-Ferchaud.La vole ferrée Rennes—Chateaubrlant nous semblant susceptible defournir des affleurements nombreux, nous avons décidé d'effectuer unecoupe du synolinorium» selon cette voie. Le délai assez court de notreséjour nous a obligé à limiter cette coupe au périmètre de la concession des Mines de Saint-Pierremont, c'est-à-dire au Sud, le passage àniveau du Pâtis et au Nord la gare de Martigné-Ferohaud, soit environ6 kms de voie ferrée.Il est bien évident que si le plus souvent, la voie noue a offertde très beaux affleurements, par contre quelquefois, des remblais, desétayages le long des talus nous ont obligé à nous en éloigner pour fairede la prospection dans les champs, prairies et lits des ruisseaux.Il nous a semblé préférable, pour réduire au minimum les pertes detemps en transports, de commencer cette étude stratlgraphique par le— —--Sud. Nous avons donc pris, comme point de départ, l'anticlinal dela forêt d'Aralze, qui, formé de grès armoricains nous offrait de plusl'avantage d'un repère stratlgraphique certain
Rapport géologique au sujet du réseau hydrographique des environs de Liffré (Ille et Vilaine)
No full textMA122
Steady oscillations of systems with non-linear and unsymmetrical elasticity
No full textThe paper discusses the oscillations of systems with arbitrary elastic characteristics under arbitrary excitation. It presents a simple method for deriving forced motions from free undamped motions. A detailed treatment of free motions is given first. Special methods are offered for the evaluation of the time integral over the interval in which is small. The substitution (with the amplitude of the motion) is shown to make the integrand finite at all points, and hence to permit a graphical evaluation of the integral. Undamped oscillations under harmonic excitation are derived from free oscillations by changing the excitation from a time function into a space function through the assumption that and are related as in the free motion. By combining with the elastic restoring force , a new effective is obtained --- to which there corresponds a new "free" motion, which in turn furnishes a second approximation for the relation between and , and hence a new function . A new effective and a new "free" motion are then found; and the cycle is repeated until the relation between and ceases to change. In general, the process converges rapidly. The accuracy can be checked at any stage of the work. Special methods are suggested to facilitate the drawing of response curves for various intensities of the excitation. A discussion is given of the general nature of the curves connecting the excitation intensity in with the oscillation frequency . For a particularly convenient expression of the relation between and , the use of two parameters is suggested --- being the elastic force for , and being the natural frequency corresponding to . By generally similar processes, damped motions under harmonic excitation are derived from harmonically excited undamped motions or from free motions. A convenient method is offered for the construction of response curves from the curves for the undamped forced motion, by applying a correction based on the minimum force required to maintain the damped motion at . Although a direct superimposition of the effects of different harmonics in is not possible because of the non-linearity of , the method can be used no matter what form the excitation has --- so long as it is periodic. The method is shown to apply also when the frequencies of the excitation and of the motion are multiples or sub-multiples of each other. Furthermore, the method remains valid when there are nonlinearities in the inertia and damping terms of the equation of motion. At thorough study is made of the stability of the motions discussed. A general criterion of stability is offered --- based on the assumption that a motion is definitely unstable if a small disturbance tends to grow initially, and that stability exists if a disturbance has an initial tendency to annul itself. This criterion is shown to be supported by empirical knowledge as far as such knowledge exists. In an appendix, there are given charts for the harmonic analysis of oscillation curves by a method especially adapted to curves of this type. The method is based on a polygonal approximation to the curve to be analyzed, and works on a subdivision of the area under the curve into triangles. For each of these triangles, the Fourier coefficients can be read from the charts; and the final series is obtained by addition of the series for the individual triangles
Le sol des prairies normandes ; ses qualités et ses défauts: Rapport aux journées agricoles du Calvados des 8, 9 et 10 novembre 1928
No full textMA048
