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1.
Single-phase voltage source power converters (VSCs) under consideration are AC-DC current-controlled boost-type power converters with bidirectional power-handling capability. Equivalence between two series-connected two-level power converters and a single three-level power converter is considered here. Further considered is the series operation of three-level power converters. Simulation results and experimental verification for both are provided. Economical configurations of three-level power converters leading to multilevel waveforms are presented thereafter 相似文献
2.
The temperature dependence of the viscosity of the undercooled melts exhibits an important role in the study of nucleation,
crystal growth and the glass-forming ability of materials. Several attempts have been made to study the viscous behaviour
of the glass-forming melts and these investigations are mainly based on free volume theory as well as on the configurational
entropy model. In the present investigation, an attempt has been made to correlate the thermodynamic parameters with the viscosity
of the glass-forming melts and to study the temperature dependence of the viscosity of undercooled liquids on the basis of
the free volume theory as well as on the basis of the configurational entropy model of Adam and Gibbs. The entire study is
confined on the expression for thermodynamic parameters reported by the authors recently. The expression obtained has been
successfully applied to study the temperature dependence of the viscosity of the metallic, molecular and oxide glass-forming
liquids. 相似文献
3.
Anshu Dubey Klaus Weide Dongwook Lee John Bachan Christopher Daley Samuel Olofin Noel Taylor Paul M. Rich Lynn B. Reid 《Software》2015,45(2):233-244
When developing a complex, multi‐authored code, daily testing on multiple platforms and under a variety of conditions is essential. It is therefore necessary to have a regression test suite that is easily administered and configured, as well as a way to easily view and interpret the test suite results. We describe the methodology for verification of FLASH, a highly capable multiphysics scientific application code with a wide user base. The methodology uses a combination of unit and regression tests and an in‐house testing software that is optimized for operation under limited resources. Although our practical implementations do not always comply with theoretical regression‐testing research, our methodology provides a comprehensive verification of a large scientific code under resource constraints.Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
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S. T. Dubey L. Kravetz J. P. Salanitro 《Journal of the American Oil Chemists' Society》1995,72(1):23-30
The effluents and activated sludges used in benchscale biotreater units have been analyzed for nonionic alcohol ethoxylates
and their residues. Separate bench-scale units were fed linear alcohol ethoxylates (AE), highly branched and branched nonylphenol
ethoxylates. Effluents and sludges were first pretreated by a foam sublation technique to provide a gross separation of surfactants
from the environmental matrix. This step was followed by normal-phase high-performance liquid chromatography (HPLC) with either
fluorescence detection (FD) or evaporative light-scattering detection (ESLD). The AEs were derivatized with phenylisocyanate
and analyzed by normal-phase HPLC coupled with FD. At extremely low surfactant levels, pretreatment of large sample volumes
resulted in interferences on derivatization. Hence, a normal-phase HPLC method with ELSD was developed. Although some interferences
do appear using ELSD, this method appears to be a more viable alternative to derivatization/FD for very low levels of AE.
HPLC with FD and ELSD detection methods are more quantitative and provide information on the polyoxyethylene chain than is
possible with traditional methods like cobalt-thiocyanate active substance.
Presented at the 82nd AOCS Annual Meeting & Expo, May 1991, Chicago, Illinois. 相似文献
7.
M. Sterlin Leo Hudson P.K. Dubey D. Pukazhselvan Sunil Kumar Pandey Rajesh Kumar Singh Himanshu Raghubanshi Rohit. R. Shahi O.N. Srivastava 《International Journal of Hydrogen Energy》2009,34(17):7358
This paper deals with how the Hydrogen Energy may play a crucial role in taking care of the environmental scenario/climate change. The R&D efforts, at the Hydrogen Energy Center, Banaras Hindu University have been described and discussed to elucidate that hydrogen is the best option for taking care of the environmental/climate changes. All three important ingredients for hydrogen economy, i.e., production, storage and application of hydrogen have been dealt with. As regards hydrogen production, solar routes consisting of photoelectrochemical electrolysis of water have been described and discussed. Nanostructured TiO2 films used as photoanodes have been synthesized through hydrolysis of Ti[OCH(CH3)2]4. Modular designs of TiO2 photoelectrode-based PEC cells have been fabricated to get high hydrogen production rate (10.35 lh−1 m−2). However, hydrogen storage is a key issue in the success and realization of hydrogen technology and economy. Metal hydrides are the promising candidates due to their safety advantage with high volume efficient storage capacity for on-board applications. As regards storage, we have discussed the storage of hydrogen in intermetallics as well as lightweight complex hydride systems. For intermetallic systems, we have dealt with material tailoring of LaNi5 through Fe substitution. The La(Nil − xFex)5 (x = 0.16) has been found to yield a high storage capacity of 2.40 wt%. We have also discussed how CNT admixing helps to improve the hydrogen desorption rate of NaAlH4. CNT (8 mol%) admixed NaAlH4 is found to be optimum for faster desorption (3.3 wt% H2 within 2 h). From an applications point of view, we have focused on the use of hydrogen (stored in intermetallic La–Ni–Fe system) as fuel for Internal Combustion (IC) engine-based vehicular transport, particularly two and three-wheelers. It is shown that hydrogen used as a fuel is the most effective alternative fuel for circumventing climate change. 相似文献
8.
Best estimate accident analysis with uncertainty evaluation is being encouraged in the present licensing scenarios of nuclear power plants. This paper deals with uncertainty and sensitivity analysis for station blackout in PSB VVER integral test facility under the framework of coordinated research project of IAEA. Nodalization was developed using best estimate system code RELAP5/MOD3.2 and its steady state and transient level qualifications are achieved. Sampling based approaches are used to carry out uncertainty and sensitivity/importance analysis. The objective of the analysis is to get confidence for uncertainty methodology by comparing with the experimental results and extend its applicability to NPPs. Uncertainty analysis is carried out by selecting nine important input parameters with specified ranges and its uniform distributions. A design matrix of 45 × 9 is generated for variations of input parameters with the Latin Hypercube Sampling and 45 code runs were taken. Linear regression was also carried out to quantify the effect of each individual input parameter on output parameters in terms of standard rank regression coefficients. Uncertainty band in output parameters is defined between 95th and 5th percentile value. It is observed that most of the experimental values and code calculated reference values are lying within the uncertainty band. For most of the parameters, width of uncertainty band increases with transient progression time. 相似文献
9.
The flow of ambient air induced solely by buoyancy, through a vertical rod bundle has been modelled as a phenomenon in a porous medium. The rods are at uniform heat flux condition and the circular shell adiabatic. The induced flow rate was found to be controlled by a parameter ψ dependent on the heat flux, rod diameter, length, fluid properties and the bundle permeability. Measurements performed on two 7-rod bundles corroborate the theoretical predictions. Longitudinally averaged heat transfer rates from the central and peripheral rods have also been measured and average information generated for the bundle. 相似文献
10.
Alka R. Chauhan S.K. Dubey 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2008,266(8):1537-1541
Silicon oxynitride (SixOyNz) layers were synthesized by implanting 16O2+ and 14N2+ 30 keV ions in 1:1 ratio with fluences ranging from 5 × 1016 to 1 × 1018 ions cm−2 into single crystal silicon at room temperature. Rapid thermal annealing (RTA) of the samples was carried out at different temperatures in nitrogen ambient for 5 min. The FTIR studies show that the structures of ion-beam synthesized oxynitride layers are strongly dependent on total ion-fluence and annealing temperature. It is found that the structures formed at lower ion fluences (∼1 × 1017 ions cm−2) are homogenous oxygen-rich silicon oxynitride. However, at higher fluence levels (∼1 × 1018 ions cm−2) formation of homogenous nitrogen rich silicon oxynitride is observed due to ion-beam induced surface sputtering effects. The Micro-Raman studies on 1173 K annealed samples show formation of partially amorphous oxygen and nitrogen rich silicon oxynitride structures with crystalline silicon beneath it for lower and higher ion fluences, respectively. The Ellipsometry studies on 1173 K annealed samples show an increase in the thickness of silicon oxynitride layer with increasing ion fluence. The refractive index of the ion-beam synthesized layers is found to be in the range 1.54-1.96. 相似文献