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31.
Ashish Nadar Atindra Mohan Banerjee M.R. Pai R.V. Pai Sher Singh Meena R. Tewari A.K. Tripathi 《International Journal of Hydrogen Energy》2018,43(1):37-52
Supported iron oxides have been established as an important class of catalyst for high temperature sulfuric acid decomposition. With an objective to elucidate the role of support in modifying the overall catalytic properties of dispersed iron oxide catalysts, a series of supported iron oxide based catalysts, Fe2O3 (15 wt%)/MO2 (M = Zr, Ce, Ti and Si), synthesized by adsorption-equilibrium method, is investigated for sulfuric acid decomposition reaction. The structure of dispersed iron oxide phases largely depended on the nature of the support oxide as revealed by the XRD and Mössbauer studies. α-Fe2O3 is found to be present as a major phase on ZrO2 and CeO2 support while ε-Fe2O3 was the major phase on silica supported iron oxide. On the other hand, presence of mixed oxide Fe2TiO5 was revealed over TiO2 support. Strong dispersed metal oxide-support interactions inhibited the total reduction of the dispersed phase on SiO2 and TiO2 as compared to complete reduction of dispersed iron oxide on CeO2 and ZrO2 supports during temperature programmed reduction upto 1000 °C. The order of catalytic activity at a temperature of ~750 °C is observed as Fe2O3/SiO2 > Fe2TiO5/TiO2 > Fe2O3/ZrO2 > Fe2O3/CeO2, while at higher temperatures of ~900 °C the SO2 yield is found to be comparable for all catalysts. A relationship between the rate of sulfate decomposition and catalytic activity is established through detailed TG-DTA investigations of sulfated catalyst and support. Considerable influence of the support oxide on the composition, structure, redox properties, morphology and catalytic activities of the active iron oxide dispersed phase has been observed. Thus, the support oxides operate as a critical component in the complex supported metal oxide catalysts and these findings might influence the design and development of future high temperature sulfuric acid decomposition catalysts. 相似文献
32.
Sushma A. Rawool Mrinal R. Pai A.M. Banerjee R.D. Bapat Chandrani Nayak A.K. Tripathi 《International Journal of Hydrogen Energy》2018,43(3):1271-1284
We have demonstrated earlier that maximum H2 generated @ 1.167 l/h/m2 over Cu0.02Ti0.98O2-δ photocatalyst with apparent quantum efficiency, AQE of 7.5% and solar fuel efficiency, SFE of 3.9% under sunlight. With an aim to scale-up the solar photocatalytic hydrogen process to pilot plant, optimization studies at lab scale as well as in upscaled photoreactors were performed over Cu0.02Ti0.98O2-δ, photocatalyst under UV/visible and sunlight. Cu0.02Ti0.98O2-δ was synthesized by facile sol-gel route and characterized by relevant techniques. Several operational parameters were investigated in order to finalize the conditions which are most favourable for photocatalytic hydrogen yield. Factors such as photocatalyst loadings, v/v concentration of sacrificial reagent, replacement of methanol by industrial waste glycerol, role of different configuration of light source with reactor, effect of stirring during the photocatalytic reaction, effect of fluctuations of solar flux at hourly basis, illumination area on hydrogen yield were studied. Contribution of each factor in determining the hydrogen yield was quantified. Relative standard deviation in hydrogen yield as a function of each factor was estimated. Our findings suggest that in addition to catalyst loadings and sacrificial reagent, improved dispersion of photocatalyst obtained by stirring the reaction mixture in horizontal geometry resulted in enhanced H2 yield. Hydrogen yield obtained at lab scale can be appropriately extrapolated with respect to illumination area instead of weight of photocatalyst. A relative standard deviation (RSD) of ± 3.82% and ± 4.53% in H2 yield was calculated for sunny and cloudy days in time zone of 10.30–16.30 h IST. Deviation of H2 yield was more on cloudy days and beyond 16:30 h. These studies have provided a daily window of 11:00–15:00 h to be utilized throughout the year for a commercial scaled up process, prohibiting the illumination during less productive hours of the day for shaping the improved economics of solar hydrogen generation. Our results obtained at lab scale would be useful to perform sunlight driven scaled –up photocatalytic process using low cost visible light efficient photocatalyst, Cu0.02Ti0.98O2-δ. 相似文献
33.
Deepmala Gupta Arvind Kumar Dwivedi Madhu Tripathi 《Lakes & Reservoirs: Research and Management》2019,24(4):391-393
Knowledge of the length–weight relationships (LWRs) of fish is an important tool to understand fish body form, growth pattern, stock management and their conservation. The present study focused on investigating the length–weight relationships for five catfish species, Pachypterus atherinoides (Bloch, 1794), belonging to family Horabagridae; Batasio batasio (Hamilton, 1822) family Bagridae; Bagarius yarrelli (Sykes, 1839), family Gogangra viridescens (Hamilton, 1822); and Sisor rhabdophorus (Hamilton, 1822) belonging to family Sisoridae. Specimens were collected from the middle stretch of the Ganga River in India from November 2016 to May 2018. A total of 174 specimens of five fish species were collected, and their total lengths were measured to the nearest centimetre and the body weight to the nearest gram. The value of the parameter slope (b) of LWRs of the five species ranged from 2.86 (B. yarrelli) to 3.16 (G. viridescens), with a mean value of 2.99. The results of the present study documented the new maximum total length (TL) for P. atherinoides and S. rhabdophorus. The present study also provides the first reference regarding LWRs for S. rhabdophorus. 相似文献
34.
Wireless Networks - The effectiveness of wireless sensor network (WSN) in Internet of Thing (IoT) based large scale application depends on the deployment method along with the routing protocol. The... 相似文献
35.
Volkan Kumtepeli Yulong Zhao Maik Naumann Anshuman Tripathi Youyi Wang Andreas Jossen Holger Hesse 《国际能源研究杂志》2019,43(9):4127-4147
The rapid increase of renewable energy sources made coordinated control of the distributed and intermittent generation units a more demanded task. Matching demand and supply is particularly challenging in islanded microgrids. In this study, we have demonstrated a mixed‐integer quadratic programming (MIQP) method to achieve efficient use of sources within an islanded microgrid. A unique objective function involving fuel consumption of diesel generator, degradation in a lithium‐ion battery energy storage system, carbon emissions, load shifting, and curtailment of the renewable sources is constructed, and an optimal operating point is pursued using the MIQP approach. A systematic and extensive methodology for building the objective function is given in a sequential and explicit manner with an emphasis on a novel model‐based battery aging formulation. Performance of the designed system and a sensitivity analysis of resulting battery dispatch, diesel generator usage, and storage aging against a range of optimization parameters are presented by considering real‐world specifications of the Semakau Island, an island in the vicinity of Singapore. 相似文献
36.
Patel Sapna Kumar Dushyant Chaurasiya Nitesh Kumar Tripathi Shweta 《Semiconductors》2019,53(13):1797-1803
Semiconductors - In the present paper, analytical modeling of surface potential and drain current for hetero-dielectric double gate tunnel FET (HDG-TFET) has been done. The two dimensional (2D)... 相似文献
37.
Semiconductors - The quest for downscaling of devices has led to novel configurations with better performance parameters of which Junction Less (JL) MOSFET is an important configuration regarding... 相似文献
38.
Gobinda Gyawali ;Hyung-Suk Kim ;Khagendra Tripathi ;Tae-Ho Kim ;Soo Wohn Lee 《材料科学技术学报》2014,30(8):796-802
Ni—SiC—h/BN composite materials were prepared by electrodeposition technique with the dispersion of SiC(10 g/L) and h/BN nanosheets(10 g/L) in a nickel sulfamate electrolytic bath.Different ratio of sodium dodecyl sulfate(SDS) and cetyltrymethyl ammonium bromide(CTAB) surfactants were used to evaluate the effect of surfactants on the properties of the electrodeposited composite coatings.The coating samples were characterized by scanning electron microscopy,X-ray diffraction,Vickers microhardness test,scratch and tribology tests.The results revealed that the co-deposition of nanoparticles was significantly influenced by surfactants during electrodeposition process.Pyramidal or polyhedral nickel crystallites were observed at higher ratio of SDS/CTAB while smaller oval grains with refined surface morphologies were obtained at lower ratio of SDS/CTAB surfactants.In addition,wt%of particles co-deposition was increased,and Vickers microhardness,wear and coefficient of friction of the electrodeposited composite coatings were improved at increased CTAB and decreased SDS contents in the electrolyte during electrodeposition process. 相似文献
39.
A general procedure based on the method of lines is presented for the full-wave analysis of propagation structures having layered substrates with step inhomogeneities in each layer. Examples of such structures include microslab lines and microstrip near a substrate edge. It is shown that with this extended method of lines technique the frequency-dependent characteristics, including the modal impedance, current distribution, and other properties of these structures, can be calculated. To illustrate the technique, typical structures such as microstrips on a finite-width dielectric slab and microstrips near a substrate edge are considered, and the effect of the proximity of the edge on the propagation characteristics of the microstrip is computed. For the case of a microstrip near a substrate edge, the numerical results obtained are compared with measured values of propagation constants, showing that the proximity effect is predicted to within 1% 相似文献
40.
Using channel state dependent packet scheduling to improve TCPthroughput over wireless LANs 总被引:1,自引:0,他引:1
Pravin Bhagwat Partha Bhattacharya Arvind Krishna Satish K. Tripathi 《Wireless Networks》1997,3(1):91-102
In recent years, a variety of mobile computers equipped with wireless communication devices have become popular. These computers
use applications and protocols, originally developed for wired desktop hosts, to communicate over wireless channels. Unlike
wired networks, packets transmitted on wireless channels are often subject to burst errors which cause back to back packet
losses. In this paper we study the effect of burst packet errors and error recovery mechanisms employed in wireless MAC protocols
on the performance of transport protocols such as TCP. Most wireless LAN link layer protocols recover from packet losses by
retransmitting lost segments. When the wireless channel is in a burst error state, most retransmission attempts fail, thereby
causing poor utilization of the wireless channel. Furthermore, in the event of multiple sessions sharing a wireless link,
FIFO packet scheduling can cause the HOL blocking effect, resulting in unfair sharing of the bandwidth. This observation leads
to a new class of packet dispatching methods which explicitly take wireless channel characteristics into consideration in
making packet dispatching decisions. We compare a variety of channel state dependent packet (CSDP) scheduling methods with
a view towards enhancing the performance of transport layer sessions. Our results indicate that by employing a CSDP scheduler
at the wireless LAN device driver level, significant improvement in channel utilization can be achieved in typical wireless
LAN configurations.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献