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Cruz, Raphael da C. ; CARDOSO, Márcio José Estillac de Mello ; BARCIA, Oswaldo Esteves. (2013).
Resumo: This work presents a study of the influence of the molecular weight on the thermodynamic modeling of the viscosity of non-newtonian polymer solutions. The employed model is based on the absolute rate theory of Eyring and on the solution theory of McMillan-Mayer. The Soave-Redlich-Kwong equation of state was adopted for the calculation of the excess molar McMillan-Mayer free energy derived from the osmotic pressure of the solution. The model presents parameters that take account separately the different possibilities of interaction in the macromolecular environment. As the tertiary structure of a polymer molecule can be affected by applied shear stress, only the parameters related with the intramolecular interactions are dependent of the shear stress. The experimental rheological curves for different molecular weights of polyethylene glycol aqueous solutions have been measured at several concentrations, within the whole polymer solubility range, at 298.15 K and 0.1 MPa. The dependence on the molecular weight for all parameters of the model was analyzed and characterized. The dependence of the shear sensitive parameters on the shear stress was also studied.
REBELLO, J. M. A. ; AREIZA, MARIA C. L. ; CAMERINI, C. ; ROCHA, J. V. (2013).
Resumo: Duplex stainless steel (DSS) presents a good combination of mechanical properties and high corrosion resistance. Its microstructure is composed of two phases with different physical properties: delta ferrite and gamma austenite. The best properties of DSS for in service applications are achieved when these phases are in equal proportions. However, exposition to high temperatures, may entail undesired consequences impairing the mechanical and corrosion properties of the material. Eddy current testing (ECT) has already been used for DSS inspection and microstructure characterization, mainly to detect the presence of deleterious phases, such as sigma. However, conventional ECT was not able to quantify different amounts of austenite and ferrite in the absence of deleterious phases. The present study focuses on the experimental and computational problem of DSS inspection using ECT in saturated magnetic conditions in order to identify different amounts of austenite and ferrite within the DSS microstructure. Samples containing ferrite to austenite ratio equal to 50/50, 70/30 and 80/20 respectively were brought to saturation as designed in the simulations and the ECT was applied presenting a very good result. Saturated low frequency ECT condition proved to be a reliable methodology in quantifying delta ferrite and gamma austenite phases in DSS.
DE ASSIS, KIOSHY S. ; ROCHA, A.C. ; MARGARIT-MATTOS, ISABEL C.P. ; SERRA, F.A.S. ; MATTOS, OSCAR R. (2013).
Resumo:
BARCIA, O. E.; PONTES, J. ; MANGIAVACCHI, N. ; MATTOS, Oscar Rosa. (2013).
Resumo: A new meta-heuristics is introduced here: the Multi-Particle Collision Algorithm (M-PCA). The M-PCA is based on the implementation of a function optimization algorithm driven for a collision process of multiple particles. A parallel version for the M-PCA is also described. The complexity for PCA, M-PCA, and a parallel implementation for the MPCA is developed. The efficiency for optimization for PCA and M-PCA is evaluated for some test functions. The performance of the parallel implementation of the M-PCA is also presented. The results with M-PCA produced better optimized solutions for all test functions analyzed.
LEITAO, ROBERTA G. ; PEREIRA, GABRIELA R. ; LIMA, INAYA ; PALUMBO, ANTONIO ; SOUZA, PEDRO A. V. R. ; ANJOS, MARCELINO J. ; NASCIUTTI, LUIS E. ; LOPES, RICARDO T. (2013).
Resumo: Synchrotron X-ray imaging systems with fluorescence techniques were developed for biomedical research at the Brazilian Synchrotron Laboratory. Two different X-ray fluorescence systems were implemented to analyze human prostate samples with and without disorders.
