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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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Computing Edge States without Hard Truncation
We present a numerical method which accurately computes the discrete spectrum and associated bound states of semi-infinite Hamiltonians which model electronic “edge” states localized at boundaries of one- and two-dimensional crystalline materials. The problem is nontrivial since arbitrarily large finite “hard” (Dirichlet) truncations of the Hamiltonian in the infinite bulk direction tend to produce spurious bound states partially supported at the truncation. Our method, which overcomes this difficulty, is to compute the Green's function of the semi-infinite Hamiltonian by imposing an appropriate boundary condition in the bulk direction; then, the spectral data is recovered via Riesz projection. We demonstrate our method's effectiveness by studies of edge states at a graphene zig-zag edge in the presence of defects modeled both by a discrete tight-binding model and a continuum PDE model under finite difference discretization. Our method may also be used to study states localized at domain wall-type edges in one- and two-dimensional materials where the edge Hamiltonian is infinite in both directions; we demonstrate this for the case of a tight-binding model of distinct honeycomb structures joined along a zig-zag edge. Here, we expect our method to be useful for designing novel devices based on precise wave-guiding by edge states.
Rad-Hard, Miniaturized, Scalable, High-Voltage Switching Module for Power Applications Rad-Hard, Miniaturized
A paper discusses the successful development of a miniaturized radiation hardened high-voltage switching module operating at 2.5 kV suitable for space application. The high-voltage architecture was designed, fabricated, and tested using a commercial process that uses a unique combination of 0.25 micrometer CMOS (complementary metal oxide semiconductor) transistors and high-voltage lateral DMOS (diffusion metal oxide semiconductor) device with high breakdown voltage (greater than 650 V). The high-voltage requirements are achieved by stacking a number of DMOS devices within one module, while two modules can be placed in series to achieve higher voltages. Besides the high-voltage requirements, a second generation prototype is currently being developed to provide improved switching capabilities (rise time and fall time for full range of target voltages and currents), the ability to scale the output voltage to a desired value with good accuracy (few percent) up to 10 kV, to cover a wide range of high-voltage applications. In addition, to ensure miniaturization, long life, and high reliability, the assemblies will require intensive high-voltage electrostatic modeling (optimized E-field distribution throughout the module) to complete the proposed packaging approach and test the applicability of using advanced materials in a space-like environment (temperature and pressure) to help prevent potential arcing and corona due to high field regions. Finally, a single-event effect evaluation would have to be performed and single-event mitigation methods implemented at the design and system level or developed to ensure complete radiation hardness of the module.
Hard and super-hard metal alloys and methods for making the same
The present invention relates to Cu33Al17 alloys and Cu33Al17-based bulk alloys and coatings that exhibit significantly increased hardness characteristics compared to traditional copper-aluminum alloys.
Note: Alignment/focus dependent core-line sensitivity for quantitative chemical analysis in hard x-ray photoelectron spectroscopy using a hemispherical electron analyzer
X-ray photoelectron spectroscopy is an established technique for quantitative chemical analysis requiring accurate peak intensity analysis. We present evidence of focus/alignment dependence of relative peak intensities for peaks over a broad kinetic energy range with a hemispherical electron analyzer operated in a position imaging mode. A decrease of over 50% in the Ag 2p{sub 3/2} to Ag 3d ratio is observed in a Ag specimen. No focus/alignment dependence is observed when using an angular imaging mode, necessitating the use of angular mode for quantitative chemical analysis.
Fluence thresholds for grazing incidence hard x-ray mirrors
X-ray Free Electron Lasers (XFELs) have the potential to contribute to many fields of science and to enable many new avenues of research, in large part due to their orders of magnitude higher peak brilliance than existing and future synchrotrons. To best exploit this peak brilliance, these XFEL beams need to be focused to appropriate spot sizes. However, the survivability of X-ray optical components in these intense, femtosecond radiation conditions is not guaranteed. As mirror optics are routinely used at XFEL facilities, a physical understanding of the interaction between intense X-ray pulses and grazing incidence X-ray optics is desirable. We conducted single shot damage threshold fluence measurements on grazing incidence X-ray optics, with coatings of ruthenium and boron carbide, at the SPring-8 Angstrom compact free electron laser facility using 7 and 12 keV photon energies. The damage threshold dose limits were found to be orders of magnitude higher than would naively be expected. The incorporation of energy transport and dissipation via keV level energetic photoelectrons accounts for the observed damage threshold.
A novel synthesis of polymeric CO via useful hard x-ray photochemistry
Abstract not provided
Hard-Magnet L1[subscript 0]-CoPt Nanoparticles Advance Fuel Cell Catalysis
Abstract not provided
hardness relationships of new nickel-rich nickel-titanium-hafnium alloys developed for tribological
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Measurement of the dependence of transverse energy production at large pseudorapidity on the hard-scattering kinematics of proton–proton collisions at s = 2.76 TeV with ATLAS
N/A
Study of the hard double-parton scattering contribution to inclusive four-lepton production in pp collisions at s = 8 TeV with the ATLAS detector
Not Available
The Bionanoprobe: Synchrotron-Based Hard X-ray Fluorescence Microscopy for 2D/3D Trace Element Mapping
Trace elements, particularly metals, play an important role in a large variety of cellular processes in a biological system. In the context of biological organisms and tissues, the term trace element means that over the entire organisms an element is present at only trace levels, 100ppm or lower. Trace element distribution and content can be analyzed using several techniques, for example, visible light optical fluorescence imaging, energy-dispersive X-ray spectroscopy on an election microscope, synchrotron-based X-ray fluorescence (XRF) imagine,