The two-dimensional plane shear layers for high Reynolds numbers are simulated using the transien... more The two-dimensional plane shear layers for high Reynolds numbers are simulated using the transient explicit Spectral Collocation method. The fast and slow air streams are submitted to different densities. A temporally growing mixing layer, developing from a hyperbolic tangent velocity profile to which is superposed an infinitesimal white-noise perturbation over the initial condition, is studied. In the same way, a spatially growing mixing layer is also study. In this case, the flow in the inlet of the domain is perturbed by a time dependent white noise of small amplitude. The structure of the vorticity and the density are visualized for high Reynolds number for both cases studied. Broad-band kinetic energy and temperature spectra develop after the first pairing are observed. The results showed that similar conclusions are obtained for the temporal and spatial mixing layers. The spreading rate of the layer in particular is in good agreement with the works presented in the literature.
Developments in Laser Techniques and Fluid Mechanics, 1997
Quantitative velocity measurements have been performed in Taylor-Couette flow using the PHANTOMM ... more Quantitative velocity measurements have been performed in Taylor-Couette flow using the PHANTOMM flow tagging technique. The results illustrate the expected three-dimensional features of the flow including the presence of well defined Taylor cells at low Taylor numbers and gradual transition to turbulence as the Taylor number is increased. The spectral density and auto correlation functions were computed over the Taylor number range 21.1 × 103 to 1.10 × 1011. For Taylor numbers less than approximately 6 × 107, the flow is dominated by large toroidal eddies with a wavelength the same order as the gap size. As the Taylor number is increased above this value, the flow displays more irregular motions, associated with the Gortler instability or instability of the second kind. Nevertheless, even for the highest Taylor number studied in this work, the structure is far from random, and the flow exhibits an almost periodic behavior. The results show the potential of the PHANTOMM technique to investigate spatial instabilities in confined flows.
The transition of a flow of a liquid film from counter-current to co-current to a gas flow is kno... more The transition of a flow of a liquid film from counter-current to co-current to a gas flow is known as the flooding phenomenon. In this paper is shown a quite criterions mathematical formulation in the form to identify with success the flooding point. One applies thus the conservation equations for a bi-dimensional and isothermical flow. Using the theorem of the PI of Vashy-Buckingham one makes a dimensional analysis in order to obtain parameters that make it possible to establish an asymptotic analysis for the a-dimensional equations and reduce a set of PDEs to a unique PDE for the thickness of the liquid film. This PDE will be decomposed in an equation for the permanent problem and another referring to the transient. It will be developed only the non–linear permanent equation applying the spectral method of collocation of Chebychev for its discretization. One intends in this paper to stress the physical interpretation of the equations for the thickness of the liquid film obtained ...
Nous avons realise une etude experimentale sur l'ecoulement d'un film liquide ruisselant ... more Nous avons realise une etude experimentale sur l'ecoulement d'un film liquide ruisselant sur une des parois verticale d'une conduite rectangulaire en presence d'un gaz circulant a contre courant. Cette etude a ete conduite de facon a mettre en evidence l'evolution de la structure de l'interface gaz-liquide. Nous avons observe cette evolution de la structure de l'interface en fonction de la vitesse du gaz a l'aide d'une camera rapide et nous avons mesure l'epaisseur du film liquide, a l'aide de deux types de sondes. Les proprietes statistiques et la dimension de l'attracteur etrange de cette variable ont ete determinees. Nous avons egalement mesure le gradient de pression dans l'ecoulement de gaz tout le long de la section d'essais et finalement nous avons compare nos mesures globales (points de flooding) a des correlations empiriques et a des modeles theoriques
We prepared a simultaneous-equations model solved by vector-error-correction. The findings indica... more We prepared a simultaneous-equations model solved by vector-error-correction. The findings indicated the relevance of household consumption and private fixed investment in leading the growth of the Brazilian economy. The trade balance proved also to be a valuable asset for economic growth. The transfers to social security showed weak exogeneity in the short run; however, with significant and positive impacts on the economic growth. The transfers to states and municipalities proved to be quite exogenous, in both the short and long run, with negative impacts on the economic growth. The taxes classified into three distinct groups are income taxes and social contributions on net income (TISC), social contributions on payroll (SCP), and taxes on goods and services (TGS). The results showed that TISC was distortionary taxes, in both the short and long run, SCP was distortionary taxes in the short run, and TGS was nondistortionary in the long run.
The efficient market model has been questioned. In econometric, efficient markets are those that ... more The efficient market model has been questioned. In econometric, efficient markets are those that have no linear correlation. A lack of linear correlation is not sufficient, since the return series can also produce non-linear dependence. Thus, this study presents the method of the coefficients of correlation and bi-correlation of Portmanteau in analyses of financial markets series. The market efficiency was evaluated through the windows percentage that has significant coefficients, correlations or bi-correlations. The results reinforce the criticism of the efficient market model and demonstrated the existence of significant nonlinearities in all indices studied and the presence of evolutionary trajectories.
A visualization study and Quantitative velocity measurements have been performed in Taylor-Couett... more A visualization study and Quantitative velocity measurements have been performed in Taylor-Couette flow with a medium-gap (η= 0.356), over a large range of Taylor numbers (2.1x10 4 < Ta < 1.1x10 11 ), with the outer cylinder fixed and the inner cylinder rotating about its axis. Quantitative velocity measurements were carried out using the PHANTOMM flow tagging technique. For visualization study, two techniques were used: the PHANTOMM technique that allowed flow structure visualization from small to moderate Taylor numbers, and the Particle Streak Imaging, PSI (the flow was seeded with neutrally buoyant polystyrene micro spheres) that permitted to flow structure visualization from moderate to high Taylor numbers. The results illustrate the expected three-dimensional features of flow and presence of Taylor cells at low Taylor numbers. Our study examined the interplay between small and large scales present in the flow as well as showed the gradual transition to turbulence with in...
Estruturamos um modelo de painel para simular a Curva Ambiental de Kuznets, observando as diferen... more Estruturamos um modelo de painel para simular a Curva Ambiental de Kuznets, observando as diferencas entre os paises na emissao de CO2, em funcao do desenvolvimento social e economico. A relacao entre o PIB per capita e a emissao de CO2 per capita se comporta, segundo a previsao da Curva Ambiental de Kuznets na forma de N. Os resultados demonstraram que o PIB per capita constitui a variavel explanatoria com menor impacto sobre a emissao de CO2 per capita, e que o impacto ambiental cresce, essencialmente, em funcao do desenvolvimento das economias (desenvolvimento economico, desenvolvimento social e qualidade de vida).
Este trabalho objetiva estabelecer um panorama da educação superior do Brasil e do Canadá, com am... more Este trabalho objetiva estabelecer um panorama da educação superior do Brasil e do Canadá, com amparo nos pressupostos da TQM e dos modelos de qualidade para a educação. A pesquisa é classificada metodologicamente como básica, qualitativa e descritiva. E, ainda do ponto de vista da forma, como quantitativa, a partir da análise dos índices de desempenho das IES, com base nos dados estatísticos fornecidos por órgãos oficiais. Diante do contexto educacional que se instalou no Brasil a partir dos anos noventa e com amparo nos pressupostos dos modelos de qualidade específicos para educação e da TQM aplicada à educação superior, analisou-se a relação estabelecida entre os fatores que compõem o processo de educação superior. Conclui-se, a partir da análise descritiva das condições socioeconômica e populacional dos dois países, que os índices apresentados pelo sistema de educação superior brasileiro, de forma geral, não difere dos índices considerados ideais pela OCDE, porém, há que se cons...
The two-dimensional plane shear layers for high Reynolds numbers are simulated using the transien... more The two-dimensional plane shear layers for high Reynolds numbers are simulated using the transient explicit Spectral element Collocation method. The fast and slow air streams are submitted to the different densities. A temporally growing mixing layer, developing from a hyperbolic tangent velocity profile to which is superposed an infinitesimal white-noise perturbation over the initial condition, is studied. In the same way, a spatially growing mixing layer is also study. In this case, the flow in the inlet of the domain is perturbed by a time dependent white noise of small amplitude. For all cases studied, the structure of the vorticity , transversal velocity and the internal energy are visualized for high Reynolds number. One shows that broadband kinetic energy and temperature spectra develop after the first pairing. The results showed that similar conclusions are obtained for the temporal and spatial mixing layer. Particularly, the spreading rate of the layer in very good agreemen...
The two-dimensional plane shear layers for high Reynolds numbers are simulated using the transien... more The two-dimensional plane shear layers for high Reynolds numbers are simulated using the transient explicit Spectral Collocation method. The fast and slow air streams are submitted to different densities. A temporally growing mixing layer, developing from a hyperbolic tangent velocity profile to which is superposed an infinitesimal white-noise perturbation over the initial condition, is studied. In the same way, a spatially growing mixing layer is also study. In this case, the flow in the inlet of the domain is perturbed by a time dependent white noise of small amplitude. The structure of the vorticity and the density are visualized for high Reynolds number for both cases studied. Broad-band kinetic energy and temperature spectra develop after the first pairing are observed. The results showed that similar conclusions are obtained for the temporal and spatial mixing layers. The spreading rate of the layer in particular is in good agreement with the works presented in the literature.
Developments in Laser Techniques and Fluid Mechanics, 1997
Quantitative velocity measurements have been performed in Taylor-Couette flow using the PHANTOMM ... more Quantitative velocity measurements have been performed in Taylor-Couette flow using the PHANTOMM flow tagging technique. The results illustrate the expected three-dimensional features of the flow including the presence of well defined Taylor cells at low Taylor numbers and gradual transition to turbulence as the Taylor number is increased. The spectral density and auto correlation functions were computed over the Taylor number range 21.1 × 103 to 1.10 × 1011. For Taylor numbers less than approximately 6 × 107, the flow is dominated by large toroidal eddies with a wavelength the same order as the gap size. As the Taylor number is increased above this value, the flow displays more irregular motions, associated with the Gortler instability or instability of the second kind. Nevertheless, even for the highest Taylor number studied in this work, the structure is far from random, and the flow exhibits an almost periodic behavior. The results show the potential of the PHANTOMM technique to investigate spatial instabilities in confined flows.
The transition of a flow of a liquid film from counter-current to co-current to a gas flow is kno... more The transition of a flow of a liquid film from counter-current to co-current to a gas flow is known as the flooding phenomenon. In this paper is shown a quite criterions mathematical formulation in the form to identify with success the flooding point. One applies thus the conservation equations for a bi-dimensional and isothermical flow. Using the theorem of the PI of Vashy-Buckingham one makes a dimensional analysis in order to obtain parameters that make it possible to establish an asymptotic analysis for the a-dimensional equations and reduce a set of PDEs to a unique PDE for the thickness of the liquid film. This PDE will be decomposed in an equation for the permanent problem and another referring to the transient. It will be developed only the non–linear permanent equation applying the spectral method of collocation of Chebychev for its discretization. One intends in this paper to stress the physical interpretation of the equations for the thickness of the liquid film obtained ...
Nous avons realise une etude experimentale sur l'ecoulement d'un film liquide ruisselant ... more Nous avons realise une etude experimentale sur l'ecoulement d'un film liquide ruisselant sur une des parois verticale d'une conduite rectangulaire en presence d'un gaz circulant a contre courant. Cette etude a ete conduite de facon a mettre en evidence l'evolution de la structure de l'interface gaz-liquide. Nous avons observe cette evolution de la structure de l'interface en fonction de la vitesse du gaz a l'aide d'une camera rapide et nous avons mesure l'epaisseur du film liquide, a l'aide de deux types de sondes. Les proprietes statistiques et la dimension de l'attracteur etrange de cette variable ont ete determinees. Nous avons egalement mesure le gradient de pression dans l'ecoulement de gaz tout le long de la section d'essais et finalement nous avons compare nos mesures globales (points de flooding) a des correlations empiriques et a des modeles theoriques
We prepared a simultaneous-equations model solved by vector-error-correction. The findings indica... more We prepared a simultaneous-equations model solved by vector-error-correction. The findings indicated the relevance of household consumption and private fixed investment in leading the growth of the Brazilian economy. The trade balance proved also to be a valuable asset for economic growth. The transfers to social security showed weak exogeneity in the short run; however, with significant and positive impacts on the economic growth. The transfers to states and municipalities proved to be quite exogenous, in both the short and long run, with negative impacts on the economic growth. The taxes classified into three distinct groups are income taxes and social contributions on net income (TISC), social contributions on payroll (SCP), and taxes on goods and services (TGS). The results showed that TISC was distortionary taxes, in both the short and long run, SCP was distortionary taxes in the short run, and TGS was nondistortionary in the long run.
The efficient market model has been questioned. In econometric, efficient markets are those that ... more The efficient market model has been questioned. In econometric, efficient markets are those that have no linear correlation. A lack of linear correlation is not sufficient, since the return series can also produce non-linear dependence. Thus, this study presents the method of the coefficients of correlation and bi-correlation of Portmanteau in analyses of financial markets series. The market efficiency was evaluated through the windows percentage that has significant coefficients, correlations or bi-correlations. The results reinforce the criticism of the efficient market model and demonstrated the existence of significant nonlinearities in all indices studied and the presence of evolutionary trajectories.
A visualization study and Quantitative velocity measurements have been performed in Taylor-Couett... more A visualization study and Quantitative velocity measurements have been performed in Taylor-Couette flow with a medium-gap (η= 0.356), over a large range of Taylor numbers (2.1x10 4 < Ta < 1.1x10 11 ), with the outer cylinder fixed and the inner cylinder rotating about its axis. Quantitative velocity measurements were carried out using the PHANTOMM flow tagging technique. For visualization study, two techniques were used: the PHANTOMM technique that allowed flow structure visualization from small to moderate Taylor numbers, and the Particle Streak Imaging, PSI (the flow was seeded with neutrally buoyant polystyrene micro spheres) that permitted to flow structure visualization from moderate to high Taylor numbers. The results illustrate the expected three-dimensional features of flow and presence of Taylor cells at low Taylor numbers. Our study examined the interplay between small and large scales present in the flow as well as showed the gradual transition to turbulence with in...
Estruturamos um modelo de painel para simular a Curva Ambiental de Kuznets, observando as diferen... more Estruturamos um modelo de painel para simular a Curva Ambiental de Kuznets, observando as diferencas entre os paises na emissao de CO2, em funcao do desenvolvimento social e economico. A relacao entre o PIB per capita e a emissao de CO2 per capita se comporta, segundo a previsao da Curva Ambiental de Kuznets na forma de N. Os resultados demonstraram que o PIB per capita constitui a variavel explanatoria com menor impacto sobre a emissao de CO2 per capita, e que o impacto ambiental cresce, essencialmente, em funcao do desenvolvimento das economias (desenvolvimento economico, desenvolvimento social e qualidade de vida).
Este trabalho objetiva estabelecer um panorama da educação superior do Brasil e do Canadá, com am... more Este trabalho objetiva estabelecer um panorama da educação superior do Brasil e do Canadá, com amparo nos pressupostos da TQM e dos modelos de qualidade para a educação. A pesquisa é classificada metodologicamente como básica, qualitativa e descritiva. E, ainda do ponto de vista da forma, como quantitativa, a partir da análise dos índices de desempenho das IES, com base nos dados estatísticos fornecidos por órgãos oficiais. Diante do contexto educacional que se instalou no Brasil a partir dos anos noventa e com amparo nos pressupostos dos modelos de qualidade específicos para educação e da TQM aplicada à educação superior, analisou-se a relação estabelecida entre os fatores que compõem o processo de educação superior. Conclui-se, a partir da análise descritiva das condições socioeconômica e populacional dos dois países, que os índices apresentados pelo sistema de educação superior brasileiro, de forma geral, não difere dos índices considerados ideais pela OCDE, porém, há que se cons...
The two-dimensional plane shear layers for high Reynolds numbers are simulated using the transien... more The two-dimensional plane shear layers for high Reynolds numbers are simulated using the transient explicit Spectral element Collocation method. The fast and slow air streams are submitted to the different densities. A temporally growing mixing layer, developing from a hyperbolic tangent velocity profile to which is superposed an infinitesimal white-noise perturbation over the initial condition, is studied. In the same way, a spatially growing mixing layer is also study. In this case, the flow in the inlet of the domain is perturbed by a time dependent white noise of small amplitude. For all cases studied, the structure of the vorticity , transversal velocity and the internal energy are visualized for high Reynolds number. One shows that broadband kinetic energy and temperature spectra develop after the first pairing. The results showed that similar conclusions are obtained for the temporal and spatial mixing layer. Particularly, the spreading rate of the layer in very good agreemen...
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