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Tube Type (tube + type)
Selected AbstractsSome recent finite volume schemes to compute Euler equations using real gas EOSINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 12 2002T. Gallouët Abstract This paper deals with the resolution by finite volume methods of Euler equations in one space dimension, with real gas state laws (namely, perfect gas EOS, Tammann EOS and Van Der Waals EOS). All tests are of unsteady shock tube type, in order to examine a wide class of solutions, involving Sod shock tube, stationary shock wave, simple contact discontinuity, occurrence of vacuum by double rarefaction wave, propagation of a one-rarefaction wave over ,vacuum', , Most of the methods computed herein are approximate Godunov solvers: VFRoe, VFFC, VFRoe ncv (,, u, p) and PVRS. The energy relaxation method with VFRoe ncv (,, u, p) and Rusanov scheme have been investigated too. Qualitative results are presented or commented for all test cases and numerical rates of convergence on some test cases have been measured for first- and second-order (Runge,Kutta 2 with MUSCL reconstruction) approximations. Note that rates are measured on solutions involving discontinuities, in order to estimate the loss of accuracy due to these discontinuities. Copyright © 2002 John Wiley & Sons, Ltd. [source] Raman scattering from double-walled carbon nanotubesJOURNAL OF RAMAN SPECTROSCOPY, Issue 2 2008H. Kuzmany Abstract Raman scattering from double-walled carbon nanotubes is reported with particular emphasis on the response from the radial breathing mode (RBM) of the inner-shell tubes. The unexpected large number of very narrow lines observed is explained by the growth of one and the same inner tube type in different outer tubes in a highly shielded environment. The response of the RBM and of the G-line is used to analyze the transition from peapods to double-walled carbon nanotubes. During the transformation process the Raman response disappears for a short time, indicating the existence of some Raman dark matter. By preparing the starting peapods from heterofullerenes such as (C59N)2 or 13C-substituted fullerenes, hetero-nanotubes can be grown where nitrogen or the 13C atoms are incorporated into the inner tube wall. Copyright © 2007 John Wiley & Sons, Ltd. [source] Co-current and Countercurrent Configurations for a Membrane Dual Type Methanol ReactorCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 1 2008R. Rahimpour Abstract A dynamic model for a membrane dual-type methanol reactor was developed in the presence of catalyst deactivation. This reactor is a shell and tube type where the first reactor is cooled with cooling water and the second one with feed synthesis gas. In this reactor system, the wall of the tubes in the gas-cooled reactor is covered with a palladium-silver membrane which is only permeable to hydrogen. Hydrogen can penetrate from the feed synthesis gas side into the reaction side due to the hydrogen partial pressure driving force. Hydrogen permeation through the membrane shifts the reaction towards the product side according to the thermodynamic equilibrium. Moreover, the performance of the reactor was investigated when the reaction gas side and feed gas side streams are continuously either co-current or countercurrent. Comparison between co-current and countercurrent mode in terms of temperature, activity, methanol production rate as well as permeation rate of hydrogen through the membrane shows that the reactor in co-current configuration operates with lower conversion and also lower permeation rate of hydrogen but with longer catalyst life than does the reactor in countercurrent configuration. [source] Role of Albumin Coating of Tympanostomy Tubes: Long-Term Clinical EvaluationTHE LARYNGOSCOPE, Issue 12 2007Teemu J. Kinnari MD Abstract Objective: Our previous work has shown that albumin coating of tympanostomy tubes prevented adhesion of proteins or bacteria on the tube surface in vitro and in a 9-month prospective follow-up study. This study was continued until all tubes were extruded. Study Design: A prospective, clinical trial. Methods: The randomized, double-blind clinical trial had 149 patients. The randomization was revealed after the follow-up period of 9 months. The number of tube sequelae in ears with human serum albumin (HSA)-coated titanium tympanostomy tubes was compared with the contralateral ears with uncoated, otherwise identical titanium tubes. The follow-up continued until all tubes were extruded, followed by evaluation of each tympanostomized patient. Results: No significant difference between the two tube types emerged after the 9-month follow-up. Among the patients younger than 2 years, one of the three typical bacteria causing acute otitis media (AOM), Streptococcus pneumoniae, Haemophilus influenzae, or Moraxella catarrhalis, was found in 45% of all bacterial cultures taken during AOM. However, among patients older than 2, one of these bacteria appeared in 17% of all the bacterial cultures and in 8% of cultures taken during the summer. Conclusions: After the first 9 follow-up months, no difference was found in the sequelae related to uncoated and HSA-coated tubes. The typical bacteria causing AOM were found less frequently among patients older than 2 years. A profile of tympanostomy patients in Finland will be given. [source] | ||||||||||