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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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Experimental assignment of many-electron excitations in the photoionization of NiO
The absorption of a photon and the emission of an electron is not a simple, two-particle process. The complicated many-electron features observed during core photoionization can therefore reveal many of the hidden secrets about the ground and excited-state electronic structures of a material. Careful analysis of the photon-energy dependence of the Ni KLL Auger deexcitation spectra at and above the Ni 1s photoionization threshold has identified the satellite structure that appears in both the photoelectron emission and the x-ray absorption spectra of NiO as Ni metal 3d e g → Ni metal 3d e g and O ligand 2p e g → Ni metal 3d e g charge-transfer excitations, respectively. These assignments clarify the conflicting theoretical predictions of the last five decades in addition to other anomalous effects in the spectroscopy of this unique material.
Experimental realization of crossover in shape and director field of nematic tactoids
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Intrinsic Mechanism for Anisotropic Magnetoresistance and Experimental Confirmation in Co{sub x}Fe{sub 1-x} Single-Crystal Fims.
Using first-principles transport calculations, we predict that the anisotropic magnetoresistance (AMR) of single-crystal CoxFe1-x alloys is strongly dependent on the current orientation and alloy concentration. An intrinsic mechanism for AMR is found to arise from the band crossing due to magnetization-dependent symmetry protection. These special k points can be shifted towards or away from the Fermi energy by varying the alloy composition and hence the exchange splitting, thus allowing AMR tunability. The prediction is confirmed by delicate transport measurements, which further reveal a reciprocal relationship of the longitudinal and transverse resistivities along different crystal axes.
Novel experimental setup for megahertz X-ray diffraction in a diamond anvil cell at the High Energy
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The Influence of Spectral Albedo on Bifacial Solar Cells: A Theoretical and Experimental Study
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Analysis and Experimental Quantification of 1.2-kV 4H-SiC Split-Gate Octagonal MOSFET
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Experimental Results from the 1.2 MA 2.2 m Diameter Linear Transformer Driver at Sandia National Labs.
Abstract not provided.
Experimental Evaluation of Load Rejection Over-Voltage from Grid-Tied Solar Inverters
This paper investigates the impact of load rejection over-voltage (LRO) from commercially available grid-tied photovoltaic (PV) solar inverters. LRO can occur when a local feeder or breaker opens and the power output from a distributed energy resource exceeds the load power. Simplified models of current controlled inverters can over-predict over-voltage magnitudes, thus it is useful to quantify testing. The load rejection event was replicated using a hardware testbed at the National Renewable Energy Laboratory (NREL), and a set of commercially available PV inverters was tested to quantify the impact of LRO for a range of generation-to-load ratios. The magnitude and duration of the over-voltage events are reported in this paper along with a discussion of characteristic inverter output behavior. The results for the inverters under test showed that maximum over-voltage magnitudes were less than 200 percent of nominal voltage, and much lower in many test cases. These research results are important because utilities that interconnect inverter-based DER need to understand their characteristics under abnormal grid conditions.
Grid-forming Inverter Experimental Testing of Fault Current Contributions.
Abstract not provided.
Inverse Liner Z-Pinch: An Experimental Pulsed Power Platform for Studying Radiative Shocks
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Experimental warming in a dryland community reduced plant photosynthesis and soil CO 2 efflux although the relationship between the fluxes remained unchanged
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