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Gupta, A

Publications and source records attributed to Gupta, A.

8 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

An international benchmark for wind plant wakes from the American WAKE ExperimeNt (AWAKEN)

This article introduces the first benchmark study within the International Energy Agency Wind Task 57 framework, focusing on wind plant wakes. Leveraging data from the American WAKE ExperimeNt (AWAKEN), the benchmark aims to assess the accuracy of simulation tools in modeling wind plant wakes and their impact on the downstream flow under diverse inflow conditions. The AWAKEN field campaign, conducted in Oklahoma from 2022 to 2024, provides unprecedented observations of wind plant-atmosphere interactions, thus offering a large dataset to validate numerical models of different complexity. The benchmark will include three phases—code calibration, blind comparison, and iteration—allowing participants to refine their numerical models based on the feedback from the benchmark team. This article describes the benchmark case study selected from observations providing details on atmospheric conditions, wake evidence, and wind turbine operation. The benchmark’s structure and timeline, along with the expected publication of results, are discussed as well. This collaborative effort aims to enhance the accuracy of wind plant wake simulations, thus contributing to the improvement of wind energy production estimates.

17 WIND ENERGY↗
DOE OSTI2016

Beam Energy Dependence of the Third Harmonic of Azimuthal Correlations in Au+Au Collisions at RHIC

In this paper, we present results from a harmonic decomposition of two-particle azimuthal correlations measured with the STAR detector in Au + Au collisions for energies ranging from √sNN = 7.7 to 200 GeV. The third harmonic v$2\atop{3}${ 2 } = , where Φ1 - Φ2 is the angular difference in azimuth, is studied as a function of the pseudorapidity difference between particle pairs Δη = η1-η2 . Nonzero v$2\atop{3}${ 2 } is directly related to the previously observed large- Δη narrow- ΔΦ ridge correlations and has been shown in models to be sensitive to the existence of a low viscosity quark gluon plasma phase. For sufficiently central collisions, v$2\atop{3}${ 2 } persist down to an energy of 7.7 GeV, suggesting that quark gluon plasma may be created even in these low energy collisions. In peripheral collisions at these low energies, however, v$2\atop{3}${ 2 } is consistent with zero. Finally, when scaled by the pseudorapidity density of charged-particle multiplicity per participating nucleon pair, v$2\atop{3}${ 2 } for central collisions shows a minimum near √sNN = 20 GeV .

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2015

Observation of Transverse Spin-Dependent Azimuthal Correlations of Charged Pion Pairs in p ↑+p at $\sqrt{s}$ =200 GeV

We report the observation of transverse polarization-dependent azimuthal correlations in charged pion pair production with the STAR experiment in p↑+p collisions at RHIC. These correlations directly probe quark transversity distributions. We measure signals in excess of 5 standard deviations at high transverse momenta, at high pseudorapidities η > 0.5, and for pair masses around the mass of the ρ meson. This is the first direct transversity measurement in p+p collisions. Comparing the results to data from lepton-nucleon scattering will test the universality of these spin-dependent quantities.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2013

Is disaggregation the holy grail of energy efficiency? The case of electricity

This paper aims to address two timely energy problems. First, significant low-cost energy reductions can be made in the residential and commercial sectors, but these savings have not been achievable to date. Second, billions of dollars are being spent to install smart meters, yet the energy saving and financial benefits of this infrastructure - without careful consideration of the human element - will not reach its full potential. We believe that we can address these problems by strategically marrying them, using disaggregation. Disaggregation refers to a set of statistical approaches for extracting end-use and/or appliance level data from an aggregate, or whole-building, energy signal. In this paper, we explain how appliance level data affords numerous benefits, and why using the algorithms in conjunction with smart meters is the most cost-effective and scalable solution for getting this data. We review disaggregation algorithms and their requirements, and evaluate the extent to which smart meters can meet those requirements. Research, technology, and policy recommendations are also outlined. (C) 2012 Elsevier Ltd. All rights reserved.

Armel, KC↗
DOE OSTI2012

Textured growth of Co film on CoO (fcc) layer; Structural studies using EDXRD beamline at Indus-2

Co film of 13 nm thickness has been deposited on native oxide (CoO) layer using electron beam evaporation technique. CoO (fcc) of 2.3 nm thickness has been prepared by oxidizing surface of 50 nm thick Co (fcc) by thermal annealing. The structure of the sample has been investigated in detail using in-plane and out-of-plane energy dispersive grazing incidence x-ray diffraction (GIXRD) at EDXRD beamline, Indus-2, RRCAT, Indore. It is found that the growth of the Co film takes place with preferential orientation of c-axis perpendicular to the film plane, which results in structure induced magnetic anisotropy with easy axis normal to the film plane.

36 MATERIALS SCIENCE↗
DOE OSTI2012

Effect of exogenous electron shuttles on growth and fermentative metabolism in Clostridium sp. BC1

In this study, the influence exogenous electron shuttles on the growth and glucose fermentative metabolism of Clostridium sp. BC1 was investigated. Bicarbonate addition to mineral salts (MS) medium accelerated growth and glucose fermentation which shifted acidogenesis (acetic- and butyric-acids) towards solventogenesis (ethanol and butanol). Addition of ferrihydrite, anthraquinone disulfonate, and nicotinamide adenine dinucleotide in bicarbonate to growing culture showed no significant influence on fermentative metabolism. In contrast, methyl viologen (MV) enhanced ethanol- and butanol-production by 28- and 12-fold, respectively with concomitant decrease in hydrogen, acetic- and butyric-acids compared to MS medium. The results show that MV addition affects hydrogenase activity with a significant reduction in hydrogen production and a shift in the direction of electron flow towards enhanced production of ethanol and butanol.

08 HYDROGEN↗
DOE OSTI2011

Interdiffusion in W/Si Multilayers with Boron Carbide Interlayers

W/Si multilayers with B{sub 4}C as a diffusion barrier were deposited using ion beam sputtering technique. It was found that incorporation of B{sub 4}C at both interfaces of Si enhances the reflectivity of the multilayer. Though the interface of W/Si or W/B{sub 4}C has been studied in literature, what happens at Si/B{sub 4}C interfaces is largely unknown. This is primarily due to absence of contrast between Si/B{sub 4}C for x-rays. For neutrons there is significant contrast between Si and B{sub 4}C, therefore we used neutron reflectivity to study thermal stability of Si/B{sub 4}C multilayers. It was found that up to an annealing temperature of 573 K, the multilayer remains intact however at higher temperature interdiffusion starts.

36 MATERIALS SCIENCE↗