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31.
UNSTEADY FREE CONVECTIVE MHD FLOW AND MASS TRANSFER THROUGH POROUS MEDIUM IN A ROTATING SYSTEM WITH FLUCTUATING HEAT SOURCE/SINK AND CHEMICAL REACTION
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Rabi Narayan Barik Gouranga Charan Dash Maheswar Kar 《Journal of Applied Analysis & Computation》2014,4(3):231-244
An investigation of unsteady MHD free convective flow and mass transfer during the motion of a viscous incompressible fluid through a porous medium in the presence of heat source, bounded by an infinite vertical porous surface, in a rotating system is presented. The porous plane surface and the porous medium are assumed to rotate in a solid body rotation. The vertical surface is subject to uniform constant suction perpendicular to it and the temperature at this surface fluctuates in time about a non-zero constant mean. Analytical expressions for the velocity, temperature and concentration fields are obtained using perturbation technique. Normal 0 false false false EN-US X-NONE X-NONE 相似文献
32.
根据有旋特征线理论,设计出了沿程马赫数下降规律可控的轴对称基准流场,分析了基准流场的几何参数(前缘压缩角及中心体半径)的影响规律,发现选取较小的前缘压缩角和中心体半径有利于得到性能优良的基准流场;然后在设计状态Ma=6时研究了三种典型的马赫数下降规律对这种轴对称流场性能的影响。最后考虑了粘性的影响,并进行了粘性修正探索,结果表明,采用附面层位移厚度修正方法后,基准流场的壁面压力分布和无粘情况吻合良好。 相似文献
33.
Gupta Kalyan Kali Sen Begum Bilkis Ara Ghosh Sakti Prosad 《Transition Metal Chemistry》1998,23(3):295-299
Oxidations of glycolaldehyde (GA) to glyoxal by osmium(VIII), iridium(IV) and platinum(IV) have been investigated in aqueous
solution, and the orders with respect to each [reactant] determined. The reaction involving iridium(IV) takes place through
intermediate formation of free radicals in a MeCO2Na-MeCO2H buffer medium, whereas a one-step two-electron transfer process occurs in the oxidations by OsVIII and PtIV in an alkaline medium. Mechanisms consistent with the experimental findings are proposed.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
34.
Pulse radiolysis technique has been employed to study the reactions of oxidizing (√OH, N3√) and reducing radicals (e−aq, CO2√−, acetone ketyl radical) with 2-hydroxy-3-methoxybenzaldehyde (o-vanillin) at different pH. Hydroxyl radicals react mostly by addition reaction forming radical adducts (λmax=420 nm) and the oxidation is only a minor process even in the alkaline region. The reaction with azide radicals produced phenoxyl radicals (λmax=340 nm), which are formed on fast deprotonation of solute radical cation. Using PMZ√+/PMZ and ABTS√−/ABTS2− as the reference couple, different methods are employed to determine the one-electron reduction potential of o-vanillin and the average value is estimated to be 1.076±0.004 V vs. NHE at pH 6. The phenoxyl radicals of o-vanillin were able to oxidize ABTS2− quantitatively. The eaq− is observed to react with o-vanillin with rate constant value of 2×1010 dm3 mol−1 s−1. CO2√− and acetone ketyl radical are also observed to react with o-vanillin by electron transfer mechanism and showed the formation of transient absorption bands with λmax at 350 and 390 nm at pH 4.5 and 9.7, respectively. The pKa of the one-electron reduced species was determined to be 8.1. The results indicate that the aldehydic group is the most preferred site for electron addition. 相似文献
35.
Silver-doped indium oxide thin films have been prepared on glass and quartz substrates at room temperature (300 K) by a reactive dc magnetron sputtering technique using an alloy target of pure indium and silver (80:20 at. %). During sputtering, the oxygen flow rates are varied in the range 0.00–2.86 sccm keeping the magnetron power constant at 40 W. The resistivity of these films is in the range 100–10-3 Ω cm and they show a negative temperature coefficient of resistivity. The films exhibit p-type conductivity at an oxygen flow rate of 1.71 sccm. The work function of these silver–indium oxide films has been measured by a Kelvin probe technique. The refractive index of the films (at 632.8 nm) varies in the range 1.13–1.20. Silver doping in indium oxide narrows the band gap of indium oxide (3.75 eV). PACS 73.30.+y; 81.15.Cd; 78.20.Ci; 73.61.Le 相似文献
36.
S. Barik A.K. SrivastavaP. Misra R.V. NandedkarL.M. Kukreja 《Solid State Communications》2003,127(6):463-467
To extend the applicability of ZnO, with the bulk band gap of about 3.3 eV, into deep UV region, we have grown a multilayer of alumina capped ZnO quantum dots of mean in-plane sizes in the range of ∼1.8-3.6 nm at room temperature using alternate Pulsed Laser Deposition. Size dependent blue shift of the band gap of these dots up to ∼4.5 eV is observed in the optical absorbance spectra. The observed blue shift can be understood using the effective mass approximation in weak and strong confinement regimes. 相似文献
37.
Torsional oscillation of rigid disk in infinite transversely isotropic elastic cylinder 总被引:1,自引:1,他引:0
Sakti Pada Barik Mridula Kanoria P. K. Chaudhuri 《应用数学和力学(英文版)》2006,27(7):911-917
In the present analysis torsional oscillation of a rigid disk in an infinite transversely isotropic elastic cylinder is considered. The effects of anisotropy in the stress intensity factor are shown graphically. 相似文献
38.
Anil Kumar Barik Sachindranath Paul Ray J. Butcher Susanta Kumar Kar 《Polyhedron》2000,19(28):2651-2655
Cobalt(III) complexes, of two potentially pyrazole-derived bidentate ligands (with one ambidentate donor site), 3,5-dimethyl-1-(N-methyl/ethyl)thiocarbamylpyrazole (HL1 for N-methyl, HL2 for N-ethyl) have been synthesized and characterized by elemental analyses, IR, UV–Vis and 1H NMR spectral studies. The structure of Co(L2)3 has been determined by single-crystal X-ray diffraction studies. The complex (triclinic, space group P
) has a distorted octahedral structure with the ambidentate ligands coordinated to the Co(III) ion as uninegative bidentate chelating agents via the pyrazole ring nitrogen (tertiary) and the thiocarbamyl iminyl nitrogen atoms. The distortion from the regular octahedral geometry is ascribed to the stereochemical limitations imposed by the planar bidentate ligands. 相似文献
39.
Satyananda Barik Suresh Valiyaveettil 《Journal of polymer science. Part A, Polymer chemistry》2014,52(15):2217-2227
A facile synthetic strategy for preparing hydroxylated polymethacrylate amphiphilic block copolymers (PCzMMA‐b‐PBMMA, PFlMMA‐b‐PBMMA) incorporated with primary and secondary hydroxyl groups and electroactive moieties along the polymer backbone is reported. Full characterization, structure‐property relationship and self‐assembly of these polymers are discussed. Due to interplay of hydrophobic/hydrophilic interactions, PCzMMA‐b‐PBMMA formed a layered lattice and PFlMMA‐b‐PBMMA showed a vesicular morphology. Electropolymerization of the electroactive units led to the formation of cross‐conjugated polymer network in solution and in thin films. The network structure was characterized with a range of spectroscopic techniques. Such highly processable polymers may be of interest to applications in which a conducting amphiphilic films with strong adhesion to various substrates are required. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2217–2227 相似文献
40.
A very convenient synthesis of bis-α-amino acids from the higher homologs of Garner's aldehyde is reported. The key step is proline catalyzed asymmetric amination of the aldehydes using dibenzylazodicarboxylate. The aldehydes used are either commercially available or can easily be prepared from aspartic or glutamic acid. One of the two chiral centers in the bis-amino acids comes from the aldehyde and the other one is generated through the proline catalyzed reaction, which were high yielding and proceeded with very high diastereoselectivity (93–99%). The reported route offers a general method for the synthesis of the title compounds with desired stereochemical outcome. 相似文献