a b s t r a c tAccelerated oxidation tests were performed to determine kinetic parameters of the chronic oxidation reaction (i.e. slow, continuous, and persistent) of PCEA graphite in contact with helium coolant containing low moisture concentrations in high temperature gas-cooled reactors. To the authors' knowledge such a study has not been done since the detailed analysis of reaction of H-451 graphite with steam (Velasquez, Hightower, Burnette, 1978). Since that H-451 graphite is now unavailable, it is urgently needed to characterize chronic oxidation behavior of new graphite grades that are being considered for use in gas-cooled reactors. The Langmuir-Hinshelwood mechanism of carbon oxidation by water results in a non-linear reaction rate expression, with at least six different parameters. They were determined in accelerated oxidation experiments that covered a large range of temperatures (800-1100°C), and partial pressures of water (15-850 Pa) and hydrogen (30-150 Pa) and used graphite specimens thin enough (4 mm) in order to avoid diffusion effects. Data analysis employed a statistical method based on multiple likelihood estimation of parameters and simultaneous fitting of non-linear equations. The results show significant material-specific differences between graphite grades PCEA and H-451 which were attributed to microstructural dissimilarity between the two materials. It is concluded that kinetic data cannot be transferred from one graphite grade to another.
New generalized approach, including an improved theory of atmospheric circulation in combination with the hydrodynamic model (with correct account of turbulence in atmosphere of the urban area) and the Arakawa-Schubert method of calculation of cloud convection and theory of complex geophysical field is applied to the simulation of heat and air transfer in atmosphere of industrial region. The modelling ventilation data (mesocirculation) parameters over territory of Odessa, as well as the area of the Fukushima power plant after 2011 accident are presented.
Amorphous and liquid Fe80B20 and Fe75B25 alloys are investigated by means of X‐ray diffraction. The interference functions of the amorphous and liquid state are similar but the quantitative differences cannot be explained by a temperature factor only. Interference functions are calculated for microcrystalline Fe3B‐clusters in dependence on size. The theoretical curves are similar for a diameter of 0.6 nm to that of liquid FeB and for a diameter of 0.8 nm to that of amorphous FeB.
Here we describe and experimentally confirm the localization of charged microparticles outside the area of a radio-frequency Paul trap. We consider the nonlinear effective potential formed by the trap, treating the field independently for different electrodes of the trap. To approach the proposed model to reality, we also consider the nonlinear effects originating from the viscousity of surrounding medium. Proposed approach allows to conduct an analytical description of the effective potential and define quasi-equilibrium points both inside and outside the trap. Predictions of the proposed model are in full compliance with obtained experimental results.
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