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81.
spectra of gamma irradiated mixed crystals showed F band, which shifts towards low energy side with the composition of iodine ions in the mixed crystals. 相似文献
82.
Mixing of coaxial jets within a tube in the presence of blockage has been numerically studied. This configuration is encountered
during the modelling of flow and heat transfer in CVD (chemical vapour deposition) reactors. For the conditions prevailing in the reactor, the Reynolds numbers are low and flow can be taken to be laminar
and incompressible. The unsteady forms of the governing equations have been solved by a finite volume method that can treat
complex three-dimensional geometries. The algorithm is a two-step procedure, wherein the first step predicts the velocity
field using an assumed pressure field. The second step corrects the fields using a Poisson equation to obtain the pressure
corrections. Advection terms have been treated by a hybrid upwind-central difference technique. The computer code developed
is fully three-dimensional, though most computations of the present study have been carried out for two-dimensional geometry.
Results have been obtained in the form of velocity vector plots, wall shear stress variation on the block and the tube wall,
isotherms and temperature profiles. The flow and heat transfer characteristics of jet mixing have been explored in terms of
the Reynolds number, the jet velocity ratio, the axial position of the block, and the blockage ratio. The results obtained
show that a proper combination of the process parameters can lead to an improved performance of the CVD reactor. 相似文献
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Perumal BhavaniDharmalingam Sangeetha 《International Journal of Hydrogen Energy》2011,36(22):14858-14865
Composites were fabricated by blending SPSEBS (Sulfonated Poly Styrene Ethylene Butylene Poly Styrene) with Boron phosphate (BPO4) for proton conducting applications in fuel cells. The effects of boron phosphate and its relative loading were analyzed in terms of IEC and proton conductivity. Water and methanol uptake of these membranes were also studied.The membranes were characterized by IR spectroscopy. Thermal stability was studied by TGA and DSC analyses. Surface morphology was done by Scanning Electron Microscopy (SEM). The XRD studies indicated the existence of a certain level of crystallinity in the SPSEBS, and the composite membranes. Mechanical strength of the membranes was measured by Universal Testing Machine (UTM). This paper presents the result of recent investigations to develop an optimised in-house membrane electrode assembly (MEA) preparation technique combining catalyst ink spraying and assembly hot pressing. Easy steps were chosen in this preparation technique aiming at simplification and cost reduction. 相似文献
86.
Perumal Rajakumar Kathiresan Visalakshi Shanmugam Ganesan Pichai Maruthamuthu Samuel Austin Suthanthiraraj 《Journal of Materials Science》2012,47(4):1811-1818
Novel pyreno-chalcone dendrimers 1, 2, and 3 were synthesized and their ability to act as an additive in the redox couple (I−/I3
−) of dye-sensitized nanocrystalline TiO2 solar cell has been tested. The redox couple doped with pyreno-chalcone dendrimer 3 gave a short circuit photocurrent density (J
sc) of 7.40 mA/cm2, open circuit voltage (V
oc) of 820 mV, and a fill factor of 0.51, corresponding to an overall conversion efficiency (η) of 7.89% under 40 mW/cm2 irradiation. 相似文献
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A. Kalaivanan S. Perumal N. Neelakanda Pillai K.R. Murali 《Materials Science in Semiconductor Processing》2011,14(2):94-96
Zinc oxide (ZnO) films were deposited by sol–gel dip coating using the acrylamide route. The films were doped with different concentrations of gallium in the range 250–1200 ppm. The films exhibited hexagonal structure. The grain size decreased from 100 to 10 nm as the dopant concentration increased. The resistivity of the doped samples decreased from 103 to 3×10−3 Ω cm. The band gap value shifted towards the short-wavelength region as the dopant concentration increased. XPS studies indicated doping of Ga in ZnO 相似文献