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Search Results: 1 - 10 of 32471 matches for " Roberto Alexandre; "
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Thermal Modeling of a Novel Heated Tip Injector for Otto Cycle Engines Powered by Ethanol  [PDF]
Alexandre Rezende, Jose Roberto Simoes-Moreira
Energy and Power Engineering (EPE) , 2012, DOI: 10.4236/epe.2012.42012
Abstract: This work presents a thermal modeling of a new cold-start system technology designed for Otto cycle combustion based on the electromagnetic heating principle. Firstly, the paper presents a state-of-the-art review and presents the context of automobile industry where heated injectors are necessary. The novel method of electromagnetic heating principle to solve the cold-start problem is still in the development phase and it enables engine starting at low temperatures in vehicles powered by ethanol or flex-fuel vehicles (FFV). This new system technology should be available as an alternative to replace the existing system. Currently, the cold-start system uses an auxiliary gasoline tank, which brings some inconvenience for the user. Secondly, the aim was also to create a physical model that takes into consideration all the parameters involved on the heating process such as power heating and average heat transfer coefficient. The study is based on the lumped system theory to model the ethanol heating process. From the analysis, two ordinary differential equations arise, which allowed an analytical solution. Particularly, an ethanol heating curve inside the injector was obtained, an important parameter in the process. Comparison with experimental data from other authors is also provided. Finally, a sensitivity analysis of controlling parameters such as heating power and heat transfer coefficient variation. The paper is concluded with suggestions for further studies.
A educa o em tempos de neoliberalismo
Carlos Roberto Alexandre
Trabalho, Educa??o e Saúde , 2005, DOI: 10.1590/s1981-77462005000100014
Approximate group context tree
Alexandre Belloni,Roberto I. Oliveira
Statistics , 2011,
Abstract: We study a variable length Markov chain model associated with a group of stationary processes that share the same context tree but each process has potentially different conditional probabilities. We propose a new model selection and estimation method which is computationally efficient. We develop oracle and adaptivity inequalities, as well as model selection properties, that hold under continuity of the transition probabilities and polynomial $\beta$-mixing. In particular, model misspecification is allowed. These results are applied to interesting families of processes. For Markov processes, we obtain uniform rate of convergence for the estimation error of transition probabilities as well as perfect model selection results. For chains of infinite order with complete connections, we obtain explicit uniform rates of convergence on the estimation of conditional probabilities, which have an explicit dependence on the processes' continuity rates. Similar guarantees are also derived for renewal processes. Our results are shown to be applicable to discrete stochastic dynamic programming problems and to dynamic discrete choice models. We also apply our estimator to a linguistic study, based on recent work by Galves et al (2012), of the rythmic differences between Brazilian and European Portuguese.
Opera??es com derivativos financeiros das corpora??es de economias emergentes
Farhi, Maryse;Borghi, Roberto Alexandre Zanchetta;
Estudos Avan?ados , 2009, DOI: 10.1590/S0103-40142009000200013
Abstract: as a consequence of the deepening of the international financial crisis during the second semester of 2008, several productive companies from emerging economies have registered enormous losses in the foreign exchange derivatives markets. this fact points to the speculative dynamics of corporations in the financial deregulation environment. this paper aims to articulate this logic of enterprises' behavior with the crisis and to discuss some macroeconomic effects resulting from the financial losses caused by speculative bets in the derivative markets.
Are voters fiscal conservatives? Evidence from Brazilian municipal elections
Arvate, Paulo Roberto;Mendes, Marcos;Rocha, Alexandre;
Estudos Econ?micos (S?o Paulo) , 2010, DOI: 10.1590/S0101-41612010000100003
Abstract: some papers in literature show that voters are fiscal conservatives, while others find evidence of a preference for fiscal profligacy. we use a traditional probit model to analyze the preference of brazilian municipal voters in the 2000 election. the main result suggests that voters prefer greater expenditure. we present evidence that this result is a consequence of a fiscal federalism model where there is a soft budget constraint for municipalities (institutional context). moreover, we obtained evidence that voters with different levels of schooling impose a different result on expenditure. the effect of expenditure is more marked in municipalities with a low level of literacy.
Alterations in cochlear function during induced acute hyperinsulinemia in an animal model
Angeli, Roberto Dihl;Lavinsky, Luiz;Dolganov, Alexandre;
Brazilian Journal of Otorhinolaryngology , 2009, DOI: 10.1590/S1808-86942009000500024
Abstract: hyperinsulinism secondary to peripheral insulin resistance has been described as the most frequent etiologic factor in cochlear and vestibular syndromes. aim: this experimental study recorded and analyzed evoked auditory potential changes using transtympanic electrocochleography (ecochg) during induced acute hyperinsulinism in an animal model. materials and methods: six adult male sheep were randomly divided into 2 groups. the animals were submitted to ecochg under general anesthesia, and a peripheral blood sample was collected to measure glycemia and insulinemia. animals in the intervention group (n=3) received regular human insulin iv (0.1 u/kg). the control group (n=3) received saline solution. glycemia and insulinemia were measured simultaneously with the recording of evoked potentials at 10-minute intervals during 90 minutes. results: the intervention group experienced a progressive suppression in action potential amplitude when compared to the control group (p=0.001). conclusion: data strongly suggest that acute induced hyperinsulinism suppresses cochlear function. results may be attributed to loss of na+k+atpase activity in the stria vascularis, leading to loss of endocochlear potential and subsequent depolarization of cochlear hair cells as well as of neural cells in the auditory portion of cranial nerve viii.
Estudos de Orville Derby sobre os depósitos manganesíferos do Brasil: Edi??o comemorativa dos 150 anos de nascimento do cientista
Pires, Fernando Roberto Mendes;Cabral, Alexandre Rafael;
Rem: Revista Escola de Minas , 2001, DOI: 10.1590/S0370-44672001000300007
Abstract: in commemoration of the 150th anniversary of derby's birthday a brief review of his work has been presented. from 173 scientific works, derby published 7 papers on the manganese deposits in the period 1898-1908. in two of these papers, derby defined the manganese protore "queluzite", consisting of spessartite garnet, amphibole and rhodochrosite and tephroite, later recognized by hussak. in this work we tried to compare the derby's descriptions with our thermodynamic studies applied to the equilibrium conditions, controlled by the chemicals potentials of sio2 and co2 in the protore.
Licenciamento Ambiental e amplia o da cidadania: o Caso da Hidrelétrica de Tijuco Alto [Environmental Licensing and citizenship increasing: the Tijuco Alto Hydroelectric case]
Alexandre do Nascimento Souza,Pedro Roberto Jacobi
Organiza??es & Sociedade , 2011,
Abstract: O artigo apresenta uma reflex o sobre as práticas sociais em torno de um conflito ambiental. Busca-se identificar e analisar o contexto das conflituosas rela es entre o movimento social e popula es atingidas de um lado; e IBAMA (Estado), e CBA/CNEC (Empreendedor) do outro, durante o longo processo de licenciamento ambiental do aproveitamento de Tijuco Alto no Estado de S o Paulo. O texto se apóia em pesquisas empírica e documental e tem na no o da mudan a estrutural da esfera pública de Habermas sua base conceitual da reflex o. A hipótese do estudo é que a democratiza o traz à cena novos atores sociais portadores de novas demandas, e que a amplia o dos espa os de participa o social n o foi acompanhada pelo processo de licenciamento ambiental. Um descompasso que se observa entre a experiência desses atores sociais nos espa os de participa o política com caráter deliberativo, em muitos deles, com a experiência vivenciada nos processos de licenciamento ambiental. --- Environmental Licensing and citizenship increasing: the Tijuco Alto Hydroelectric case --- Abstract --- This article presents a reflection on social practices around an environmental conflict. It searches to identify and to describe the context of conflicting relations between social movement representing affected people on one side, and state-owned IBAMA (which stands for Brazilian Environment Institute) and CBA/NEC (private stakeholders) on the other, along the enduring environmental licensing process of the use of Tijuco Alto – SP hydroelectric potential. The writing is based on empirical and documental researches and has as theoretical concept the notion of Habermas’ public sector structural changes. Our hypothesis is that democratization brings to light new social actors with new demands and that the licensing processes did not keep up with the increase of the social participation turns. A gap is seen between the experience of these social actors in the political participation turns, of deliberative nature and their actual experiences in environmental licensing processes.
Alexandre Nabil Ghobril,Roberto Giro Moori
Gest?o & Regionalidade , 2009,
Abstract: Este trabalho tem por objetivo conhecer a dinamica do alinhamento estratégico entre indústrias de bens de capital – mecanicos – e de alimentos, segundo a abordagem de Miles & Snow. Considerou-se aindústria de alimentos como cliente e direcionador estratégico para a de bens de capital (fornecedor). A pesquisa, de cunho qualitativo, fundamentou-se em entrevistas em profundidade com gestores de seis empresas fabricantes de máquinas e equipamentos, e seis empresas da indústria de alimentos. Além disso, realizou-se um Focus Group com seis gestores, sendo três de cada setor. Após a transcri o,os dados coletados e tratados pela análise de conteúdo revelaram os seguintes aspectos: (a) a rela o do contexto ambiental com a estrutura, processos organizacionais internos e sistemas de manufatura; (b) evidências de alinhamento estratégico segundo a dinamica do modelo do ciclo adaptativo proposto por Miles & Snow, que pressup e que as organiza es se desenvolvem de acordo com padr esde comportamento estratégico para coalinhar a organiza o ao ambiente.
Estudos de Orville Derby sobre os depósitos manganesíferos do Brasil: Edi o comemorativa dos 150 anos de nascimento do cientista
Pires Fernando Roberto Mendes,Cabral Alexandre Rafael
Rem: Revista Escola de Minas , 2001,
Abstract: Em comemora o ao 150o aniversário de nascimento de Derby, breve comentário de seus trabalhos é apresentado. De 173 trabalhos científicos, Derby publicou 7 artigos sobre depósitos de manganês no período 1898-1908. Em dois desses artigos, Derby definiu o protominério de manganês "queluzito", consistindo de granada espessartita, anfibolio, e rodocrosita e tefroita, posteriormente identificados por Hussak. Nesse trabalho tentamos comparar as descri es de Derby do protominério com nossos estudos termodinamicos aplicados às condi es de equilíbrio controladas pelos potenciais químicos de SiO2 e CO2 no protominério.
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