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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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At least 1,567 records · Page 87
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Characterization of a hard X-ray self-seeding diamond crystal orientation

We present a method to accurately control the photon energies for hard X-ray Self-seeding schemes with a single crystal monochromator in transmissive geometry. The energy calibration is performed by measuring which pairs of the machine pitch and yaw angles for different crystallographic planes reflect the X-ray at the same wavelength. The free parameters of an analytical formula for the self-seeding energies are determined by fitting the observed intersections and the normalized derivative with respect to the pitch and yaw angles in the observed intersections. The method requires a hard X-ray spectrometer, but it does not rely on its absolute energy calibration. Instead, identifying the self-seeded energies above the SASE background or the monochromatic notches within the SASE bandwidth is sufficient for the calibration.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2013

Extension Model: Diamond Phenolic EOS

The procedure for performing an equation of state extension is purely based on the simple assertion that one can break the standard equation of state (EOS) into a three component free energy. The three components are made of a cold curve, ion thermal, and electron thermal part. Assuming that the standard products EOS does not contain an electron thermal component, we only need to extract the cold curve and ion component. The following is a description on how I extracted the two components and extended the tables over the full SESAME density and temperature grids while preserving the limited range table.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Diamond Pixel Luminosity Telescopes

In this document, Halyo summaries her key contributions to CMS at the LHC and provide an explanation of their importance and her role in each project. At the end Halyo describes her recent research interest that includes GPU/MIC Acceleration of the High Level Trigger (HLT) to Extend the Physics Research at the LHC. A description of her work the recent promising results that she accomplished and the deliverable are also elaborated. These contribution were only possible thanks to DOE support of junior faculty research and their clear goal to promote research and innovations.

43 PARTICLE ACCELERATORS↗
DOE OSTI2018

X-Ray Thomson Scattering from Shock-Compressed Diamond Spheres on the OMEGA Laser

X-ray Thomson scattering (XRTS) is an experimental technique that can directly probe the complicated physics of warm and hot dense matter. The Compton-shifted profile of inelastically-scattered x-rays reflects the electron velocity distribution and can measure temperature and density. The ratio of elastically versus inelastically scattered x-rays is related to the number of tightly bound versus free electrons, and thus reflects the ionization state of the sample. Recent experiments highlight uncertainties in the ionization models often used to describe warm dense matter. More experimental validation of these models is needed to understand the onset of ionization in dense plasmas.

42 ENGINEERING↗
DOE OSTI2019

DiaMonD: An Integrated Multifaceted Approach to Mathematics at the Interfaces of Data, Models, and Decisions

For many problems in computational science and engineering, the so-called forward problem—solution of the underlying mathematical model to yield output quantities of interest, given input parameters—is difficult enough for frontier complex models, which are often characterized by coupled multiphysics and possibly stochastic behavior over a wide range of length and time scales. However, we face the need to move beyond the forward problem, to address what is often the ultimate goal of CS&E: decision making. This requires us to tackle a spectrum of mathematical problems that subsume, and are thus even more difficult than, the forward problem. First, given experimental data, we wish to estimate unknown parameters characterizing a model of a natural or engineered system by solving an inverse problem. Second, we seek the optimal configuration of the system (or experiments) by solving an optimal design problem. Third, the optimal operation of the system must be determined by solving an optimal control problem. And fourth, we must quantify uncertainties as they propagate through all of the preceding problems, from data to model inference to prediction and finally to optimal design and control. Optimal mathematical methods and algorithms for such end-to-end, data-to-decisions modeling and simulation of complex problems—requiring integrated solution of forward, inverse, optimization, and UQ problems for large, multiphysics, multiscale models—entails challenges of the highest order, while also presenting great opportunities for applied mathematics research. Unfortunately, research on forward, inverse, optimization, and UQ problems has all-too-often progressed in isolation. This has led to mathematical methods that perform well when considering the forward simulation in isolation, but are prohibitive or suboptimal or unstable when combined with other methods within the framework of inversion, optimization, or UQ. The reverse is also true: general-purpose methods developed within the inversion, optimization, and UQ fields often become prohibitive when applied to complex CS&E problems since they do not exploit their structure.

58 GEOSCIENCES↗
DOE OSTI2019

DiaMonD: An Integrated Multifaceted Approach to Mathematics at the Interfaces of Data, Models, and Decisions

The major goal of the project was to invent, analyze, implement, and apply new algorithms to speed up the computational simulation of complex systems in settings in which multiple simulations are needed. The main efforts we undertook are as follows: 1. Develop novel reduced order methods to reduce the costs of simulations, especially in settings (e.g., UQ, inference, optimization and control) for which numerous simulation are needed and also for nonlocal problems (e.g., fractional derivative, anomalous diffusion, nonlocal mechanics) for which lack of sparsity results in more expensive full-order simulation than encountered in partial differential equations settings; rigorous analyses as well as computational tests were carried out, 2. Develop multifidelity methods based on the usage of a variety of models having different fidelities and different costs to accelerate simulations again in settings where numerous simulations are needed or are especially expensive; rigorous analyses as well as computational tests were carried out, 3. Develop ensemble methods to reduced the costs of simulations again in settings where numerous simulations are needed or are especially expensive; rigorous analyses as well as computational tests were carried out, and 4. Analyze a model for Richardson pair dispersion in turbulent flows and develop discretization methods for the efficient and accurate approximations of the solution of the model; rigorous analyses as well as computational tests were carried out.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2021

Fabricating Diamond-like Amorphous Carbon

Using a magnetically confined hot hollow cathode PE-CVD, hydrocarbon gas is decomposed under a diluent gas to deposit hydrogenated amorphous carbon onto a sample holder. During the fabrication of the hydrogenated amorphous carbon, the electric potential, electron temperature, and electron density of the plasma are measured with a Langmuir probe. Raman spectroscopy is used to determine the structural and electronic characterization of the final hydrogenated amorphous carbon solid.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗