排序方式: 共有13条查询结果,搜索用时 46 毫秒
11.
Laminar steady state buoyancy induced flows in a two-dimensional, air filled partial open enclosure with a discrete flush
mounted iso-flux heat source on one of its walls is investigated numerically. The transport equations for energy and vorticity
are solved with the aid of the ADI finite difference scheme on uniform mesh. Because of the specific application of the present
study in the air cooling of electronic equipments, results are obtained only for a Prandtl number of 0.71 with an aspect ratio
of 1.0 for a range of Rayleigh numbers, Ra (≤105), heat flux parameter, Q and opening parameter, A
0 using constant properties and Boussinesq approximation by imposing approximate conditions at the opening. Results of flow
and temperature patterns, velocity and temperature profiles shows that the outgoing flow is governed by strong characteristics
of the cavity condition whereas the incoming flow influenced by outside conditions. It is observed that Rayleigh number considerably
affects the flow and thermal fields within the open enclosure when compared with intensity of heat flux and size of the opening.
Received on 22 January 2001 / Published online: 29 November 2001 相似文献
12.
S. Saravana Kumar M. Abdul Khadar K. G. M. Nair S. Dhara P. Magudapathy 《Journal of Raman spectroscopy : JRS》2008,39(12):1900-1906
ZnS nanocrytsals of size ∼2.5 nm were prepared by chemical precipitation technique. Pressed pellets of nanostructured ZnS were implanted with He+ ions at doses of 5 × 1014, 1 × 1015 and 5 × 1015 ions/cm2. Raman spectra of both unimplanted and He+ ion implanted samples were recorded with ultraviolet (UV) excitation. LO, 2LO, 2TO, (LO + TA) and (2TO − TA) modes of ZnS were observed in the resonance Raman spectra of the unimplanted nanostructured ZnS samples. In addition, a surface mode was observed at 294 cm−1. With the implantation of He+ ions, the 2TO mode disappeared and 2LO mode became prominent and this observation was attributed to the decrease in band gap of ZnS nanocrytsals due to ion implantation. The exciton–LO phonon coupling strength was determined from the intensity ratio of 2LO to LO modes and it was observed that the exciton–LO phonon coupling strength increases with increase in implantation dose. In the present work, we report for the first time the observation of 2TO mode in the resonance Raman spectrum of nanostructured ZnS and also the modification of exciton–LO phonon coupling strength of semiconductor nanoparticles by ion implantation. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
13.
N. A. Mohemmed Shanid M. Abdul Khadar V. G. Sathe 《Journal of Raman spectroscopy : JRS》2011,42(9):1769-1773
Nanostructured copper oxide films were prepared by the oxidation of copper films by thermal evaporation of metallic copper. Analysis of HRTEM images showed that the films of Cu2O and CuO phases had. The band gap of the nanostructured sample of Cu2O was suitable for resonance scattering by intraband Fröhlich interaction in this sample. Micro‐Raman studies revealed an intense resonance Raman peak corresponding to a forbidden mode of Cu2O. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献