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31.
Kalpana Awasthi T. P. Yadav P. R. Mishra S. Awasthi O. N. Srivastava 《Bulletin of Materials Science》2008,31(3):313-318
The macroscopic coaxial carbon cylinders (dia. ∼0.5 cm with varying lengths, ∼ 7–10 cm) consisting of aligned carbon nanotube
(CNT) stacks have been prepared by controlled spray pyrolysis method. The coaxial carbon cylinders of CNT stacks have been
formed directly inside the quartz tube. Another study is done on multi-walled CNTs (MWNTs)-polymer (e.g. polyethylene oxide
(PEO), polyacrylamide (PAM)) composite films. We have investigated the structural, electrical and mechanical properties of
MWNTs-PEO composites. Composites with different wt% (between 0 and 50 wt% of MWNTs) have been prepared and characterized by
the scanning electron microscopic technique. Enhanced electrical conductivity and mechanical strength were observed for the
MWNTs-PEO composites. We have also studied the electrical property of MWNTs-PAM composite films. 相似文献
32.
Ammonolysis of fatty acids to the corresponding fatty acid amides is efficiently catalysed by Candida antartica lipase (Novozym 435). In the present paper lipase-catalysed synthesis of erucamide by ammonolysis of erucic acid and urea in organic solvent medium was studied and optimal conditions for fatty amides synthesis were established. In this process erucic acid gave 88.74 % pure erucamide after 48 hour and 250 rpm at 60 degrees C with 1:4 molar ratio of erucic acid and urea, the organic solvent media is 50 ml tert-butyl alcohol (2-methyl-2-propanol). This process for synthesis is economical as we used urea in place of ammonia or other amidation reactant at atmospheric pressure. The amount of catalyst used is 3 %. 相似文献
33.
Nitesh Dutt Ankush Hedau Ashwani Kumar Mukesh Kumar Awasthi Sachin Hedau Chandan Swaroop Meena 《亚洲传热研究》2024,53(3):1501-1531
The thermohydraulic performance (THP) of a solar air heater (SAH) duct with staggered D-shaped ribs as roughness geometry is examined in this work using three-dimensional numerical investigation. The investigation is carried out at roughness parameters of radius of rib to transverse pitch (r/Ptv) ratios of 0.1–0.35 and longitudinal pitch to radius of rib (Plg/r) ratios of 4–10 under varied operating circumstances of Reynolds number (Re) from 10,200 to 20,200. The maximum Nusselt number (Nu) is obtained to be 81.3 at Re of 20,200, r/Ptv as 0.1, and Plg/r as 4. In contrast, the maximum friction factor (f) is obtained to be 0.0169 at Re of 10,200, r/Ptv as 0.35, and Plg/r as 4. In the range of parameters examined, the maximum enhancement in Nusselt number (Nu/Nus) is observed to be 1.35 at an optimal parameter of r/Ptv as 0.1, Plg/r as 4, and Re as 10,200. Correspondingly, the enhancement in the friction factor (f/fs) at this optimum parameter is 1.87. The maximum value of the THP parameter is found to be 1.1 at the same optimum range of parameters. In further analysis, correlations were developed for Nusselt number (Nu) and friction factor (f) in terms of r/Ptv, Plg/r, and Re with a deviation of ±2% and ±1.5%, respectively. 相似文献
34.
M. KumarR. Awasthi A.S.K. SinhaR.N. Singh 《International Journal of Hydrogen Energy》2011,36(15):8831-8838
Ternary mixed oxides of Fe, Co, and Mo with composition FexCo1-xMoO4 (x = 0.25, 0.50 & 0.75) have been prepared by a co-precipitation method and investigated as electrocatalysts for the oxygen evolution reaction (OER) in alkaline solutions. The study indicates that partial replacement of Co by Fe in the CoMoO4 matrix increases the specific surface area as well as the apparent electrocatalytic activity of the oxide; the magnitude of increase being the greatest with x = 0.25. The order for the OER with respect to OH− concentration has been observed to be ∼2 on Fe0.75Co0.25MoO4 and ∼1 on Fe0.25Co0.75MoO4 and Fe0.5Co0.5MoO4. The Tafel slopes at low overpotentials were close to 40 mV with each oxide catalyst. 相似文献
35.
M. Sterlin Leo Hudson Himanshu Raghubanshi Seema Awasthi T. Sadhasivam Ashish Bhatnager Satoru Simizu S.G. Sankar O.N. Srivastava 《International Journal of Hydrogen Energy》2014
Graphene oxide (GO) has been prepared by employing modified Staudenmaier's method through thermal exfoliation of graphite oxide. High pressure hydrogen sorption isotherms up to 50 bar of GO, reduced by thermal reduction (TR-GO), chemical reduction (CR-GO) and graphene sheets decorated with Fe nanoclusters (Fe-GS) have been investigated. Thermal reduction of GO at 623 K under high vacuum yields TR-GO. Chemical reduction of GO using hydrazine forms CR-GO. Fe-GS was synthesized through arc-discharge between the ends of two graphite rods with one rod carrying Fe nanoparticles. The surface areas of these graphene samples were determined from the nitrogen adsorption isotherm employing Brunauer, Emmett and Teller (BET) method. Kelvin's equation was used to determine the pore size distribution of all graphene based samples. Hydrogen pressure-composition isotherms (PCI) were determined at 300 K and at 77 K, between 0.1 and 50 bar. Further, in this paper, we present a comparative adsorption isotherm analysis of hydrogen and helium on TR-GO. This reveals that the volume of hydrogen and helium adsorbed by TR-GO is nearly equal. The similar uptake volume determined for both hydrogen and helium indicates the possibility of monolayer adsorption of hydrogen and also nearly similar binding energy between TR-GO and H2/He. 相似文献
36.
37.
Awasthi Abhishek Kumar Binit Nguyen Huy Hai Lee Seung Soo Chung Jae Dong 《Journal of Mechanical Science and Technology》2020,34(8):3395-3402
Journal of Mechanical Science and Technology - A numerical analysis was conducted to examine the effect of capsule shape on phase change material (PCM) melting speed. The surface parameters of the... 相似文献
38.
Wireless Personal Communications - The issue of spectrum scarcity can be alleviated by the cognitive radio technology with efficient spectrum sensing and allocation of free spectrum bands.... 相似文献
39.
The stability of the liquid/vapor interface between two concentric revolving cylinders is examined. The transfer of heat/mass is allowed at the interface. Both the cylinders rotate with different angular velocities. The fluids inside the annular region are taken as incompressible and viscous. The theory of viscous potential flow analysis is used to add the viscous effects. The normal mode technique is used to calculate the growth of perturbations. If we rotate the inner cylinder, it is seen that asymmetric disturbances have a destabilizing character at the interface but the rotation of the outer cylinder has a stabilizing effect. We found that an asymmetric disturbance destabilizes the interface if the inner cylinder rotates. It is found that the arrangement gets destabilized on rotating of the inner cylinder but rotation of the outer cylinder induces stability, and the most stable case is found when the inner cylinder is stationary and the outer cylinder is rotating. 相似文献
40.
Prabhakar Maheswari Purushothaman Raja Awasthi Durga Prasad 《Multimedia Tools and Applications》2020,79(39-40):28773-28784
Multimedia Tools and Applications - Assessment of disease severity is one of the major challenges which helps in the prediction of yield quantitatively and to decide the control factors that... 相似文献