Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “data”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,081 records · Page 60
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

DeePKS: A Comprehensive Data-Driven Approach toward Chemically Accurate Density Functional Theory

We propose a general machine learning-based framework for building an accurate and widely applicable energy functional within the framework of generalized Kohn–Sham density functional theory. To this end, we develop a way of training self-consistent models that are capable of taking large datasets from different systems and different kinds of labels. Here, we demonstrate that the functional that results from this training procedure gives chemically accurate predictions on energy, force, dipole, and electron density for a large class of molecules. It can be continuously improved when more and more data are available.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Global quantification of the dispersion effect with POLDER satellite data

Increased aerosols can modify the shape of the cloud Particle Size Distribution (PSD), thereby influencing the radiative properties of clouds, known as the Dispersion Effect (DE). However, a global, observation-based quantification of its impact on Aerosol-Cloud Interactions (ACI) is lacking, leading to DE being typically ignored in satellite-based estimates of ACI forcing. Here we propose a physics-based method that combines polarimetric satellite data on cloud PSD to achieve global observational quantification of DE’s impact on ACI in liquid-phase stratiform clouds. Globally, DE offsets ACI changes induced by droplet number concentration variation and liquid water path adjustment by 7% and −1.4%, respectively. Furthermore, a parameterization based on the global dataset of PSD shape parameters is developed to improve DE estimation in large-scale models. Both the quantification and parameterization enhance our understanding of DE and facilitate the inclusion of this non-negligible impact of DE on ACI in estimating aerosol climate forcing.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2023

Improving nuclear data evaluations with predictive reaction theory and indirect measurements

Nuclear reaction data required for astrophysics and applications is incomplete, as not all nuclear reactions can be measured or reliably predicted. Neutron-induced reactions involving unstable targets are particularly challenging, but often critical for simulations. In response to this need, indirect approaches, such as the surrogate reaction method, have been developed. Nuclear theory is key to extract reliable cross sections from such indirect measurements. We describe ongoing efforts to expand the theoretical capabilities that enable surrogate reaction measurements. We focus on microscopic predictions for charged-particle inelastic scattering, uncertainty-quantified optical nucleon-nucleus models, and neural-network enhanced parameter inference.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2013

Atomic data of tungsten for current and future uses in fusion and plasma science

Atomic physics has played an important role throughout the history of experimental plasma physics. For example, accurate knowledge of atomic properties has been crucial for understanding the plasma energy balance and for diagnostic development. With the shift in magnetic fusion research toward high-temperature burning plasmas like those expected to be produced in the ITER tokamak, the atomic physics of tungsten has become important. Tungsten will be a constituent of ITER plasmas because of its use as a plasma-facing material able to withstand high heat loads with lower tritium retention than other possible materials. Already, ITER diagnostics are being developed based on using tungsten radiation. In particular, the ITER Core Imaging X-ray Spectrometer (CIXS), which is designed to measure the core ion temperature and bulk plasma motion, is being based on the x-ray emission of neonlike tungsten ions (W{sup 64+}). In addition, tungsten emission will at ITER be measured by extreme ultraviolet (EUV) and optical spectrometers to determine its concentration in the plasma and to assess power loss and tungsten sputtering rates. On present-day tokamaks tungsten measurements are therefore being performed in preparation of ITER. Tungsten has very complex spectra and most are still unknown. The WOLFRAM project at Livermore aims to produce data for tungsten in various spectral bands: Lshell x-ray emission for CIXS development, soft x-ray and EUV M- and N-shell tungsten emission for understanding the edge radiation from ITER plasmas as well as from contemporary tokamaks, and O-shell emission for developing spectral diagnostics of the ITER divertor.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2014

Reading data stored in the state of metastable defects in silicon using band-band photoluminescence: Proof of concept and physical limits to the data storage density

The state of bistable defects in crystalline silicon such as iron-boron pairs or the boron-oxygen defect can be changed at room temperature. In this letter, we experimentally demonstrate that the chemical state of a group of defects can be changed to represent a bit of information. The state can then be read without direct contact via the intensity of the emitted band-band photoluminescence signal of the group of defects, via their impact on the carrier lifetime. The theoretical limit of the information density is then computed. The information density is shown to be low for two-dimensional storage but significant for three-dimensional data storage. Finally, we compute the maximum storage capacity as a function of the lower limit of the photoluminescence detector sensitivity.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Experimental limits on primordial black hole dark matter from the first 2 yr of Kepler data

We present our analysis on new limits of the dark matter (DM) halo consisting of primordial black holes (PBHs) or massive compact halo objects. We present a search of the first two yr of publicly available Kepler mission data for potential signatures of gravitational microlensing caused by these objects as well as an extensive analysis of the astrophysical sources of background error. These include variable stars, flare events, and comets or asteroids that are moving through the Kepler field. We discuss the potential of detecting comets using the Kepler light curves, presenting measurements of two known comets and one unidentified object, most likely an asteroid or comet. After removing the background events with statistical cuts, we find no microlensing candidates. We therefore present our Monte Carlo efficiency calculation in order to constrain the PBH DM with masses in the range of 2 × 10{sup –9} M {sub ☉} to 10{sup –7} M {sub ☉}. We find that PBHs in this mass range cannot make up the entirety of the DM, thus closing a full order of magnitude in the allowed mass range for PBH DM.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2019

Electron and photon performance measurements with the ATLAS detector using the 2015–2017 LHC proton-proton collision data

This paper describes the reconstruction of electrons and photons with the ATLAS detector, as employed for measurements and searches exploiting the complete LHC Run 2 dataset. An improved energy clustering algorithm is introduced, and its implications for the measurement and identification of electrons and photons are discussed in detail. Corrections and calibrations that affect performance, including energy calibration, identification and isolation efficiencies, and the measurement of the charge of reconstructed electron candidates are determined using up to 81 fb -1 of proton-proton collision data collected at $\sqrt{s}=$ 13 TeV between 2015 and 2017.

47 OTHER INSTRUMENTATION↗
DOE OSTI2025

Inferring demographic and selective histories from population genomic data using a 2-step approach in species with coding-sparse genomes: an application to human data

Abstract The demographic history of a population, and the distribution of fitness effects (DFE) of newly arising mutations in functional genomic regions, are fundamental factors dictating both genetic variation and evolutionary trajectories. Although both demographic and DFE inference has been performed extensively in humans, these approaches have generally either been limited to simple demographic models involving a single population, or, where a complex population history has been inferred, without accounting for the potentially confounding effects of selection at linked sites. Taking advantage of the coding-sparse nature of the genome, we propose a 2-step approach in which coalescent simulations are first used to infer a complex multi-population demographic model, utilizing large non-functional regions that are likely free from the effects of background selection. We then use forward-in-time simulations to perform DFE inference in functional regions, conditional on the complex demography inferred and utilizing expected background selection effects in the estimation procedure. Throughout, recombination and mutation rate maps were used to account for the underlying empirical rate heterogeneity across the human genome. Importantly, within this framework it is possible to utilize and fit multiple aspects of the data, and this inference scheme represents a generalized approach for such large-scale inference in species with coding-sparse genomes.

Soni, Vivak (ORCID:0000000294969562)↗
DOE OSTI2015

Constraints on models of the Higgs boson with exotic spin and parity using decays to bottom-antibottom quarks in the full CDF data set

In this study, a search for particles with the same mass and couplings as those of the standard model Higgs boson but different spin and parity quantum numbers is presented. We test two specific alternative Higgs boson hypotheses: a pseudoscalar Higgs boson with spin-parity J P = 0 – and a gravitonlike Higgs boson with J P = 2 + , assuming for both a mass of 125 GeV/c 2 . We search for these exotic states produced in association with a vector boson and decaying into a bottom-antibottom quark pair. The vector boson is reconstructed through its decay into an electron or muon pair, or an electron or muon and a neutrino, or it is inferred from an imbalance in total transverse momentum. We use expected kinematic differences between events containing exotic Higgs bosons and those containing standard model Higgs bosons. The data were collected by the CDF experiment at the Tevatron proton-antiproton collider, operating at a center-of-mass energy of √s = 1.96 TeV, and correspond to an integrated luminosity of 9.45 fb –1 . We exclude deviations from the predictions of the standard model with a Higgs boson of mass 125 GeV/c 2 at the level of 5 standard deviations, assuming signal strengths for exotic boson production equal to the prediction for the standard model Higgs boson, and set upper limits of approximately 30% relative to the standard model rate on the possible rate of production of each exotic state.

Aaltonen, Timo Antero↗
DOE OSTI2016

Detection of regional infrasound signals using array data: Testing, tuning, and physical interpretation

This work quantifies the physical characteristics of infrasound signal and noise, assesses their temporal variations, and determines the degree to which these effects can be predicted by time-varying atmospheric models to estimate array and network performance. An automated detector that accounts for both correlated and uncorrelated noise is applied to infrasound data from three seismo-acoustic arrays in South Korea (BRDAR, CHNAR, and KSGAR), cooperatively operated by Korea Institute of Geoscience and Mineral Resources (KIGAM) and Southern Methodist University (SMU). Arrays located on an island and near the coast have higher noise power, consistent with both higher wind speeds and seasonably variable ocean wave contributions. On the basis of the adaptive F-detector quantification of time variable environmental effects, the time-dependent scaling variable is shown to be dependent on both weather conditions and local site effects. Significant seasonal variations in infrasound detections including daily time of occurrence, detection numbers, and phase velocity/azimuth estimates are documented. These time-dependent effects are strongly correlated with atmospheric winds and temperatures and are predicted by available atmospheric specifications. As a result, this suggests that commonly available atmospheric specifications can be used to predict both station and network detection performance, and an appropriate forward model improves location capabilities as a function of time.

47 OTHER INSTRUMENTATION↗
DOE OSTI2012

Electron performance measurements with the ATLAS detector using the 2010 LHC proton-proton collision data

Here, detailed measurements of the electron performance of the ATLAS detector at the LHC are reported, using decays of the Z, W and J/ψ particles. Data collected in 2010 at √s = 7 TeV are used, corresponding to an integrated luminosity of almost 40 pb -1 . The inter-alignment of the inner detector and the electromagnetic calorimeter, the determination of the electron energy scale and resolution, and the performance in terms of response uniformity and linearity are discussed. The electron identification, reconstruction and trigger efficiencies, as well as the charge misidentification probability, are also presented.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗