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C3 - Artigos Publicados em Periódicos

URI permanente para esta coleçãohttps://rihomolog.furg.br/handle/1/486

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1994 - 19994

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Data inicial: 1994Data final: 1999

Resultados da Pesquisa

Agora exibindo 1 - 4 de 4
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    Experimental study of plastic deformation during sintering of cubic boron nitride compacts
    (Elsevier, 1999) Casanova, Carlos Alberto Medeiros; Balzaretti, Naira Maria; Voronin, Georgiy; Jornada, João Alziro Herz da
    In this work polycrystalline cubic boron nitride compacts (PcBN), prepared with and without binder, were sintered at 8 GPa and 1850°C using different processing times. X-ray diffraction and Raman spectroscopy were used to investigate the kinetics of plastic deformation during sintering. For compacts sintered in short processing times, both Raman and X-ray diffraction linewidths increased, indicating a high plastic deformation of the grains. For longer processing times (30–120 s) the linewidth decreased, tending to the value of the pristine cBN grains. This dependence on the processing time was interpreted as a result of the competition between the plastic deformation of the grains, dominant for short processing times, and the defect annealing process, which becomes significant for longer processing times. When aluminum binder was used for sintering, it was observed that the processing time required to recover the original linewidth is longer, and the maximum broadening of the lines occurs at a longer processing time compared to the case without binder. These results indicated that the binder phase significantly affects both plastic deformation and defect annealing processes.
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    Extended closure model for kaimal's isopleths
    (1994) Krusche, Nisia; Goedert, Joao; Moraes, Osvaldo Luiz Leal de
    A closure model for the spectral equation of turbulent kinetic energy, in the case of a steady-state and horizontally homogeneous flow in a stably stratified surface boundary layer is developed by use of systematic dimensional analysis. All resulting arbitrary functions that describe transfer mechanisms are subsequently Taylor-expanded in terms of their (small) arguments. This procedure leads to the closure of the system in terms of arbitrary constants which can subsequently be determined by fitting of observational data. The resulting solution is tested through comparison with experimental curves drawn from the Kansas experiment and with a formerly developed model.
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    Non-supervised sensory-motor agents learning
    (1996) Wazlawick, Raul Sidnei; Costa, Antonio Carlos da Rocha
    This text discusses a proposal for creation and destruction of neurons based on the sensory-motor activity. This model, called sensory-motor schema, is used to define a sensory-motor agent as a collection of activity schemata. The activity schema permits a useful distribution of neurons in a conceptual space,creating concepts based on action and sensation. Such approach is inspired in the theory of the Swiss psychologist and epistemologist Jean Piaget, and intends to make explicit the account of the processes of continuous interaction between sensory-motor agents and their environments when agents are producing cognitive structures.
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    Análise lógico-operatória do ambiente de desenvolvimento cooperativo de programação ENVY/400
    (1999) Behar, Patricia Alejandra; Costa, Antonio Carlos da Rocha
    In the present work we describe the Cooperative Programming Development Environment ENVY/400 and its piagetian logical-operatory analysis. Thus, it’s presented a model that represent the interactive process between the collective subject and the related tool. Based on it, we describe some of the logic and/or infralogic operations of the environment.