Unsteady State
Mostrando 25-36 de 44 artigos, teses e dissertações.
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25. Transient solidification of hypomonotectic and monotectic A1-Bi alloys / Solidificação transitoria de ligas hipomonotetica e monotetica do sistema A1-Bi
Ligas de alumínio dispersas com bismuto apresentam aplicações promissoras em componentes automotivos resistentes ao desgaste. Essas dispersões de elementos de baixa temperatura de fusão diminuem a dureza e escoam facilmente em condições de deslizamento, resultando em um comportamento tribológico favorável. Muitos estudos têm sido realizados a fim d
Publicado em: 2008
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26. Treatability of petrochemical industries wastewaters - case study. / Tratabilidade de águas residuárias de indústrias petroquímicas - estudo de caso.
O tratamento de águas residuárias industriais, submetido constantemente a cargas de choque, é pouco estudado no Brasil, sendo limitado o grau de conhecimento que se tem no mundo sobre os mecanismos de remoção de disruptores endócrinos nos sistemas de tratamento físico-químicos e biológicos. O presente trabalho traz um estudo de caso, envolvendo uma
Publicado em: 2008
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27. A unified discrete-time approach to the state space representation of aeroelastic systems.
In complex flow situations, it is common to use numerical tools to evaluate the aerodynamic unsteady behavior. The present work presents an alternate formulation for the state space representation of aeroelastic systems based on digital control theory that is shown to be effective and accurate for the coupling of numerical solutions with such systems. The ap
Publicado em: 2007
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28. Unsteady aerodynamic forces for aeroelastic analysis of two-dimensional lifting surfaces
The present work is part of an effort for developing a methodology for the aeroelastic analysis of two-dimensional lifting surfaces using an unsteady, Euler-based, CFD tool for the calculation of the aerodynamic operator. The CFD tool solves the flow problem with the finite-volume method applied to an unstructured grid context. The proposed methodology is ba
Journal of the Brazilian Society of Mechanical Sciences and Engineering. Publicado em: 2006-12
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29. The influence of melt convection on dendritic spacing of downward unsteady-state directionally solidified Sn-Pb alloys
Microstructures are the strategic link between materials processing and materials behavior. A dendritic structure is the most frequently observed pattern of solidified alloys. The microstructural scales of dendrites, such as primary and secondary arm spacings, control the segregation profiles and the formation of secondary phases within interdendritic region
Materials Research. Publicado em: 2006-03
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30. DEPOSIÇÃO DE PARAFINA EM ESCOAMENTO LAMINAR NA PRESENÇA DE CRISTAIS EM SUSPENSÃO / WAX DEPOSITION IN LAMINAR FLOW WITH SUSPENDED CRYSTALS
Offshore crude oil production is steadily growing. Oil transport in these cold environments (deep water) causes the precipitation of the heavy organic crude oil components like waxes. Wax deposition at the inner wall of pipelines is a serious problem in crude oil transportation causing the partial or total plugging of pipelines, increase in pumping energy an
Publicado em: 2006
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31. Modelagem da transferência de calor combinada por condução e radiação em isolantes térmicos de edificações
New insulation materials are being used in building industry to reduce electric energy consumption due to presence of HVAC (Heating, Ventilation and Air Conditioning) systems or to improve the thermal comfort of non-conditioned environments. An insulation material used in ceilings is the glass wool. The glass wool is considered as a semitransparent material,
Publicado em: 2005
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32. Influencia das variaveis de solidificação transitoria no surgimento e evolução dos espaçamentos dendriticos terciarios
Solidification thennal variables, i.e., transient metal/mold heat transfer coefficient, tip cooling rate, local solidification time and tertiary dendrite ann spacings have been measured in Sn-Pb and AI-Cu alloys directionally solidified under unsteady-state heat flow conditions. The tertiary anns seem to initiate from the secondary branches on1y when a certa
Publicado em: 2004
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33. Caracterização da microestrutura dendritica na solidificação vertical descendente de ligas AL-CU / Characterization of dendritic array during downward transient directionally solidified AL-CU alloys
The dendritic spacings are important microstructural parameters, involved in solidification processes. They can affect not only microsegregation profiles but also the formation of secondary phases within interdendritic regions, which influences mechanical properties of cast structures. A small number of studies have been carried out in order to analyze the e
Publicado em: 2004
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34. Theoretical - Experimental Analysis of Cellular and Primary Dendritic Spacings during Unidirectional Solidification of Sn-Pb Alloys
Structural parameters as grain size, dendritic and cellular spacings, segregated products, porosity and other phases are strongly influenced by the thermal behavior of the metal/mold system during solidification, imposing a close correlation between this and the resulting microstructure. Several unidirectional solidification studies with the objective of cha
Materials Research. Publicado em: 2002-09
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35. Influencia de parametros termicos de solidificação na transição colunar/equiaxial
The macroestructure of cast ingots can be characterized by either a completely columnar structure or an equiaxed structure, depending on alloy composition and solidification conditions. A more complex structure, typical of solidification in molds of high heat diffusivity, like chill and cooled molds, both structural forms. This mixed mode of solidification o
Publicado em: 2002
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36. Recent extensions of the residence time distribution concept: unsteady state conditions and hydrodynamic model developments
Two recent extensions of the residence time distribution concept are developed. The first one concerns the use of this method under transient conditions, a concept theoretically treated but rarely confirm by relevant experiments. In the present work, two experimental set-ups have been used to verify some limits of the concept. The second extension is devoted
Brazilian Journal of Chemical Engineering. Publicado em: 2000-12