Dendê, Atabaques e Berimbau. A Herança Cultural Africana na Obra de Jorge Amado

“In all the literature of Jorge Amado one feels the emphasis he gives to the mysteries of the streets of Bahia, in the power of the enchanted. I came to really understand the truth of these statements to moving to Salvador, to live with his people, with their precepts and secrets”. Zelia Gattai, The House of the Red River, 2001   These words Zelia Gattai, wife of Bahian writer Jorge Amado, may well introduce the subject of this communication, which seek to individuate the presence of some features of the African cultural heritage in his works, with the intent of highlighting, in particular, how aspects related to the mythical elements are translated by him into literature. Jorge Amado always stressed the important contribution of the traditions of African origin in the creation of that Bahian culture "mestizo syncretic" for he constantly exalted. Culture born from the union of traditions, from Europe and Africa in Bahia were joining for "Brazilianize upEm toda a literatura de Jorge Amado sente-se o destaque que ele dá aos mistérios das ruas de Bahia, no poder dos encantados. Vim compreender realmente a verdade dessas afirmações ao mudar-me para Salvador, ao conviver com seu povo, com seus preceitos e segredos. Zélia Gattai, A casa do Rio Vermelho, 2001 Estas palavras de Zélia Gattai, esposa do escritor baiano Jorge Amado, podem bem introduzir o assunto da presente comunicação, na qual procurarei individuar a presença de alguns traços da herança cultural africana na obra do autor, com o intento de evidenciar, em particular, como os aspectos relacionados aos elementos míticos são por ele transpostos para a literatura. Jorge Amado sempre salientou a importante contribuição das tradições de origem africana na criação daquela cultura baiana “mestiça e sincrética” por ele constantemente exaltada. Cultura nascida da união de tradições que, vindas da Europa e da África, na Bahia foram juntando-se, para “abrasileirar-s

Simultaneous occurrence of sliding and crossing limit cycles in piecewise linear planar vector fields

In the present study we consider planar piecewise linear vector fields with two zones separated by the straight line $x=0$. Our goal is to study the existence of simultaneous crossing and sliding limit cycles for such a class of vector fields. First, we provide a canonical form for these systems assuming that each linear system has center, a real one for $y<0$ and a virtual one for $y>0$, and such that the real center is a global center. Then, working with a first order piecewise linear perturbation we obtain piecewise linear differential systems with three crossing limit cycles. Second, we see that a sliding cycle can be detected after a second order piecewise linear perturbation. Finally, imposing the existence of a sliding limit cycle we prove that only one adittional crossing limit cycle can appear. Furthermore, we also characterize the stability of the higher amplitude limit cycle and of the infinity. The main techniques used in our proofs are the Melnikov method, the Extended Chebyshev systems with positive accuracy, and the Bendixson transformation.Comment: 24 pages, 7 figure

Investigations into the coefficient of thermal expansion of porous films prepared on AA7175 T7351 by anodizing in sulphuric acid electrolyte

The aim of this study was to investigate the Coefficient of Thermal Expansion (CTE) of anodic films on 7175 T7351 aluminium alloy and to evaluate the influence of the film characteristics on this value. In particular, effects of porosity and post-treatments, such as coloring and sealing, were studied. Beam bending analysis was used as the experimental method and a numerical finite element model was developed to verify theoretical relationships hypotheses. The values determined and the choice of experimental method were then validated by comparing the experimental cracking temperature of anodic films with a theoretical value directly depending on the previously determined CTE

Fluid mechanics approach to acoustic liner design

Fluid mechanics approach to acoustic liner desig

Mechanical behavior of black anodic films on 7175 aluminium alloy for space applications

Because of their low outgassing and their thermo-optical properties, black anodized aluminium parts are often used near optical instruments to manage thermal control in space applications. However, critical cases of flaking of the film were observed after simulated thermal ageing. To understand the mechanisms leading to flaking, the influence of the initial porosity of the film on its mechanical behavior during and after the black anodizing process has been investigated. The decrease of limit tensile stress with the porosity, the coloring and the sealing combined to thermal stresses due to the difference of thermal expansion coefficients between film and substrate have been shown to cause crazing in articular conditions. For high initial porosity films, thermal cycling ageing has a detrimental influence on the adhesion measured by scratchtesting. Numerical simulation has been used to simulate the combined effects of thermal stresses and film cracking on the stress field at the interface

Regularization estimates and Cauchy theory for inhomogeneous Boltzmann equation for hard potentials without cut-off

In this paper, we investigate the problems of Cauchy theory and exponential stability for the inhomogeneous Boltzmann equation without angular cut-off. We only deal with the physical case of hard potentials type interactions (with a moderate angular singularity). We prove a result of existence and uniqueness of solutions in a close-to-equilibrium regime for this equation in weighted Sobolev spaces with a polynomial weight, contrary to previous works on the subject, all developed with a weight prescribed by the equilibrium. It is the first result in this more physically relevant frameworkfor this equation. Moreover, we prove an exponential stability for such a solution, with a rate as close as we want to the optimal rate given by the semigroup decay of the linearized equation. Let us highlight the fact that a key point of the development of our Cauchy theory is the proof of new regularization estimates in short time for the linearized operator thanks to pseudo-differential tools.Comment: arXiv admin note: text overlap with arXiv:1709.0994