https://repositorio.ufba.br/handle/ri/34555 2026-05-03T11:26:25Z https://repositorio.ufba.br/handle/ri/14226 Título: Thermal effects on stereolithography tools during injection moulding Autor(es): Ribeiro Jr., Armando Sá; Hopkinson, Neil; Ahrens, Carlos Henrique Abstract: In this work, the changes to stereolithography (SL) resin mechanical properties during the injection moulding process were evaluated. A multi-impression SL mould was built and used to inject a series of small flat mouldings. The fixed half SL tool insert included recesses to accommodate tensile test specimens. Tensile test specimens made from SL resin were positioned in these recesses and plastic parts were injected. After injecting a predetermined number of mouldings, tensile tests were performed using the tensile test specimens. The results from the tensile tests show that the thermal cycling encountered during the injection moulding process did not significantly affect the mechanical properties of the resin. Observations indicate that decrease in the temperatures encountered in the tool may lead to longer tool life. Tipo: Artigo de Periódico 2004-01-01T00:00:00Z https://repositorio.ufba.br/handle/ri/13470 Título: Integrating UML and UPPAAL for designing, specifying and verifying component-based real-time systems Autor(es): Muniz, André Luís Nunes; Andrade, Aline Maria Santos; Lima, George Marconi de Araújo Abstract: A new tool for integrating formal methods, particularly model checking, in the development process of component-based real-time systems specified in UML is proposed. The described tool, TANGRAM (Tool for Analysis of Diagrams), performs automatic translation from UML diagrams into timed automata, which can be verified by the UPPAAL model checker. We focus on the CORBA Component Model. We demonstrate the overall process of our approach, from system design to verification, using a simple but real application, used in train control systems. Also, a more complex case study regarding train control systems is described. Tipo: Artigo de Periódico 2010-01-01T00:00:00Z https://repositorio.ufba.br/handle/ri/13276 Título: A rotating disk apparatus for assessing the biodegradation of polycyclic aromatic hydrocarbons transferring from a non-aqueous phase liquid to solutions of surfactant Brij 35 Autor(es): Bernardez, Letícia Alonso Abstract: A rotating disk apparatus was used to investigate the biodegradation of PAHs from non-aqueous phase liquids to solutions of Brij 35. The mass transfer of PAHs in absence of surfactant solution was not large enough to replenish the degraded PAHs. The addition of surfactant resulted in an overall enhancement of biodegradation rates compared to that observed in pure aqueous solution. This is because surfactant partition significant amount of PAHs into the bulk phase, where uptake occurs but the supply of PAHs to the aqueous phase through micellar solubilization at latter period limited biodegradation rates. It was demonstrated the relationship between biodegradation rate and surfactant dose and the mechanisms controlling the mass transfer of PAH from NAPLs. The satisfactory comparison of the experimental data with the predictions of a model, which parameters were determined from independent solubilization and dissolution experiments and based on the main assumption that the solutes must be present in the true aqueous phase to be degraded, allows us to conclude the absence of direct uptake of PAHs by bacteria. Tipo: Artigo de Periódico 2009-01-01T00:00:00Z https://repositorio.ufba.br/handle/ri/13140 Título: Turbulent natural convection in enclosures using large-eddy simulation with localized heating from horizontal bottom surface and cooling from vertical surfaces Autor(es): Brito, Rogerio Fernandes; Menon, Genésio José; Pirani, Marcelo José Abstract: Turbulent natural convection of air that happens into inner square cavity with localized heating from horizontal bottom surface has been numerically investigated. Localized heating is simulated by a centrally located heat source on the bottom wall, and two values of the dimensionless heat source length ∈ are considered in the present work. Solutions are obtained for several Rayleigh numbers with Prandtl number Pr = 0.70. The horizontal top surface is thermally insulated and the vertical surfaces are assumed to be the cold isothermal surfaces whereas the heat source on the bottom wall is isothermally heated. In this study, the Navier-Stokes equations are used considering a two-dimensional and turbulent flow in unsteady state. The Finite Element Method (FEM) with a Galerkin scheme is utilized for solving the conservation equations. The formulation of conservation equations is carried out for turbulent flow and the implementation of turbulent model is made by Large-Eddy Simulation (LES). The distributions of the stream function and of the temperature are determined as functions of thermal and geometrical parameters. The average Nusselt number Num is shown to increase with an increase in the Rayleigh number Ra as well as in the dimensionless heat source length ∈. The results of this work can be applied to the design of electronic components. Tipo: Artigo de Periódico 2009-01-01T00:00:00Z