An anisotropic elastic-plastic constitutive model for single and polycrystalline metals. II—Experiments and predictions concerning thin-walled tubular OFHC copper

Predictions based on an anisotropic elastic-plastic constitutive model proposed in the first part of this paper are compared with the experimental stress and strain data on OHFC copper under first torsion to about 13% and partial unloading, and then tension-torsion to about 10% along eight different loading paths. This paper also describes the deformation and stress of the thin-walled tubular specimen under finite deformation, the numerical implementation of the model, and the detailed procedure for determining the material parameters in the model. Finally, the model is extended to a general representation of the multiple directors, and the elastic-viscoplastic extension of the constitutive model is considered.

Raman scattering from an individual tubular graphite cone

　

Oxidative dehydrogenation of propane in a dense tubular membrane reactor

Oxidative dehydrogenation of propane (ODP) to propylene was investigated in a dense tubular membrane reactor made of Ba0.5Sr0.5Co0.8Fe0.2O3-delta (BSCF) at 700degreesC and 750degreesC. The propylene selectivity in the membrane reactor (44.2%) is much higher than that in the fixed-bed reactor (15%) at the similar propane conversion (23-27%). Higher propylene selectivity in the membrane reactor was attributed to the lattice oxygen (O2-) supplied through the membrane.

An amperometric detector with a tubular electrode deposited on the capillary for capillary liquid chromatography

A procedure is described for the preparation of a tubular electrode by chemical deposition of platinum at the end of a fused-silica capillary. The properties of the electrode were tested under liquid chromatographic conditions, demonstrating that both the static and the dynamic behaviour of the detection system satisfy the requirements of capillary chromatographic separations and compare well with a wall-jet amperometric system and with UV photometric detection. The detection system described is easy to prepare and does not require any time-consuming positioning of the electrode system as it is integrated into the separation part of the apparatus. (C) 1998 Elsevier Science B.V.

Partial oxidation of methane to syngas in tubular oxygen-permeable reactor

A dense Ba0.5Sr0.5Co0.8Fe0.2O3-delta membrane tube was prepared by the extruding method. Furthermore, a membrane reactor with this tubular membrane was successfully applied to partial oxidation of methane (POM) reaction, in which the separation of oxygen from air and the partial oxidation of methane are integrated in one process. At 875degreesC, 94% of methane conversion, 98% of CO selectivity, 95% of H-2 selectivity, and as high as 8.8 mL/(min (.) cm(2)) of oxygen flux were obtained. In POM reaction condition. the membrane tube shows a very good stability.