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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 1,063 records · Page 59
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

SoK: A Framework for and Analysis of Software Bill of Materials Tools

Modern software development has gradually become more complex, leveraging available open-source software and third party components. This practice has raised questions about the provenance, licensing, versioning and compliance of reused code and its dependencies. Furthermore, it is par ticularly important to review such code fragments and third party components for known-vulnerabilities before they are included in a software product. A Software Bill of Materials (SBoM) is a mechanism to achieve such an analysis, provid ing transparency and visibility into a software product to both the software developer and its respective consumer. An SBoM lists information and details about all the elements constituting a piece of software and can, therefore, be used to evaluate associated security risk. While the concept of SBoMs is growing in popularity, it is still fairly new to many organizations, causing them to potentially struggle with pro ducing and processing SBoMs and limiting their widespread adoption. In this work, we delve into the area of SBoMs and present the state-of-the-art SBoM tools, creating a framework for analysis and categorizing them based on a diverse set of features and functionalities. We are the first to provide a detailed analysis of 83 open-source SBoM tools along with a perspective on how a potential SBoM user can select a tool based on their specific requirements. Our work aims to help promote understanding of this domain, thereby encouraging and furthering its overall adoption. We additionally seek to pave a path for future work in this area by providing recommendations to tool developers and users, researchers, and standardizing organizations.

99 GENERAL AND MISCELLANEOUS↗
DOE OSTI2022

Vanadium metal-organic framework for selective adsorption

A permanently porous vanadium(II)-containing metal-organic framework (MOF) with vanadium(II) centers and methods for synthesis of such MOF frameworks are provided. Methods for using such compounds to selectively react with N2 over CH4 are provided. In the synthetic methods, a vanadium source, such as VY2(tmeda)2, where Y is a halogen and tmeda is N,N,N′,N′-tetramethylethane-1,2-diamine and a H2(ligand) are reacted in the presence of acid in a solvent at between 110° C. and 130° C. to form an intermediate product. The intermediate product is collected and washed with a washing agent, such as DMF and acetonitrile, and the vanadium(II) based MOF is activated by heating the washed intermediate product to at least 160° C. under dynamic vacuum.

Long, Jeffrey R.↗
DOE OSTI2019

Integrated Methodology for the Impact Assessment of an Uranium Mill Contaminated Site - 19031

This work describes the development of mathematical models for radionuclides distribution and transport in the environment. The applicability of the models involves an integrated approach to assess the quantitative dispersion of the radionuclides in different environmental compartments when released from uranium tailings or from other low-activity mining wastes storages. For every compartment the important pathways of contamination and the radionuclides of major concern are identified and selected, based on their chemical, physical, radiological and toxic properties. Each compartment represents an environmental media: air, soil, water, vegetation and biota. Depending on the characteristics of the sources different types of possible releases are evaluated using phenomenological models. Models of environmental release, dispersion, transport and fate within each environmental compartment, as well as models of transfer between them, are applied to a specific site. The model outputs are the radionuclides activities for each one of the environmental compartments, where relevant exposure end-points are previously identified. The methodology was applied to a specific Uranium Mill Site, referred here as the 'Mill'. The site comprises approximately 3.2 km and includes two inactive mills, former ore stockpiles areas, a partially reclaimed tailings pond disposal area and a current tailings pond disposal area. The Mill site began operations in the late 1950's extracting uranium ore by alkaline leaching. Later on, a new facility using acid leaching for extracting uranium begun to operate in 1980. The mill operated first continuously and after intermittently until its closure, in March 2006. The data required for the model input was acquired from different sources: direct measurements from this particular site and available from multiple site investigation reports (in particular, environmental data for groundwater, soil, surface water, sediments and biota); other, were selected from published data. For the unknown data, assumptions were made. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2020

Simplified Approach for Scoping Assessment of Non-LWR Source Terms

This report describes a structure to aid in evaluation of release mitigation strategies across a range of reactor technologies. The assessment performed for example reactor concepts utilizes previous studies of postulated accident sequences for each reactor concept. This simplified approach classifies release mitigation strategies based on a range of barriers, physical attenuation processes, and system performance. It is not, however, intended to develop quantitative estimates of radiological release magnitudes and compositions to the environment. Rather, this approach is intended to identify the characteristics of a reactor design concepts release mitigation strategies that are most important to different classes of accident scenarios. It uses a scoping methodology to provide an approximate, order-of-magnitude, estimate of the radiological release to the environment and associated off-site consequences. This scoping method is applied to different reactor concepts, considering the performance of barriers to fission product release for these concepts under sample accident scenarios. The accident scenarios and sensitivity evaluations are selected in this report to evaluate the role of different fission product barriers in ameliorating the source term to the environment and associated off-site consequences. This report applies this structure to characterize how release mitigation measures are integrated to define overall release mitigation strategies for High Temperature Gas Reactors (HTGRs), Sodium Fast Reactors (SFRs), and liquid fueled Molten Salt Reactors (MSRs). To support this evaluation framework, factors defining a chain of release attenuation stages, and thus an overall mitigation strategy, must be established through mechanistic source term calculations. This has typically required the application of an integral plant analysis code such as MELCOR. At present, there is insufficient evidence to support a priori evaluation of the effectiveness of a release mitigation strategy for advanced reactor concepts across the spectrum of events that could challenge the radiological containment function. While it is clear that these designs have significant margin to radiological release to the environment for the scenarios comprising the design basis, detailed studies have not yet been performed to assess the risk profile for these plants. Such studies would require extensive evaluation across a reasonably complete spectrum of accident scenarios that could lead to radiological release to the environment.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2021

System and method for grain refinement and general control of grain morphology in laser additive manufacturing

The present disclosure relates to a system for forming a material layer that may make use of an optical light source for generating an optical beam, and a beam shaping subsystem configured to shape the optical beam to generate a complex beam intensity profile. The complex shaped beam may be used to selectively melt at least portions of a bed of powder particles residing on a substrate during formation of the material layer, as the optical light source is moved. A computer may be used to control the optical light source. The complex beam intensity profile enables control over the microstructure of grains formed during melting of the powder particles as the material layer is formed.

Roehling, Tien↗
DOE OSTI2019

Elimination of CO 2 /N 2 Langmuir Sorption and Promotion of “N 2 -Phobicity” within High- T g Glassy Membranes

In this work, we demonstrate that the CO 2 /N 2 gas separation performance of alkoxysilyl-substituted vinyl-added polynorbornenes (VAPNBs) may be significantly enhanced via incorporation of the monomer 5-tris(2-methoxyethoxy)-silyl-2-norbornene. As the molar ratio of this monomer is increased, substantial increases in CO 2 /N 2 selectivity are realized with minimal decrease in CO 2 permeability. This trend ignores the traditional permeability/selectivity “tradeoff” relationship and yields an optimal membrane whose performance reaches the 2008 upper bound for CO 2 /N 2 separations. Though the inclusion of 5-tris(2-methoxyethoxy)-silyl-2-norbornene units was initially hypothesized to maximize CO 2 solubility, detailed gas sorption studies reveal that these highly glassy materials essentially lack any Langmuir sorption component and indicate that their improved CO 2 /N 2 selectivity is due to decreased N 2 solubility within the matrix. Computational modeling suggests that the source of this apparent “N 2 -phobicity” is likely explained through comparative analyses of polymer–polymer and polymer–gas interactions. Lastly, mixed-gas permeation tests are performed to provide a more realistic look at real-world gas separation performance.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2014

Estimating the Impact of Vadose Zone Sources on Groundwater to Support Performance Assessment of Soil Vapor Extraction

Soil vapor extraction (SVE) is a prevalent remediation approach for volatile contaminants in the vadose zone. To support selection of an appropriate endpoint for the SVE remedy, an evaluation is needed to determine whether vadose zone contamination has been diminished sufficiently to protect groundwater. When vapor-phase transport is an important component of the overall contaminant fate and transport from a vadose zone source, the contaminant concentration expected in groundwater is controlled by a limited set of parameters, including specific site dimensions, vadose zone properties, and source characteristics. An approach was developed for estimating the contaminant concentration in groundwater resulting from a contaminant source in the vadose zone based on pre-modeling contaminant transport for a matrix of parameter value combinations covering a range of potential site conditions. An interpolation and scaling process are then applied to estimate groundwater impact for site-specific conditions.

58 GEOSCIENCES↗
DOE OSTI2016

Improved instrumentation for intensity-, wavelength-, temperature-, and magnetic field-resolved photoconductivity spectroscopy

We report instrumentation for photovoltage and photocurrent spectroscopy over a larger continuous range of wavelengths, temperatures, and applied magnetic fields than other instruments described in the literature: 350 nm≤λ≤1700 nm, 1.8 K≤T≤300 K, and B≤9 T. This instrument uses a modulated monochromated incoherent light source with total power<30 μW in combination with an LED in order to probe selected regions of non-linear responses while maintaining low temperatures and avoiding thermal artifacts. The instrument may also be used to measure a related property, the photomagnetoresistance. We demonstrate the importance of normalizing measured responses for variations in light power and describe a rigorous process for performing these normalizations. We discuss several circuits suited to measuring different types of samples and provide analysis for converting measured values into physically relevant properties. Uniform approaches to measurement of these photoproperties are essential for reliable quantitative comparisons between emerging new materials with energy applications. - Highlights: • A novel instrument for measuring photoconductivity and photocurrents of materials and devices. • Continuous parameter space: 350 nm≤λ≤1700, 1.8 K≤T≤300 K, and B≤9 T. • Methodology for treating non-linear responses and variable lamp intensity. • Mathematical detail for extracting properties of materials from measured values is provided.

36 MATERIALS SCIENCE↗
DOE OSTI2013

BL LAC CANDIDATES FOR TeV OBSERVATIONS

BL Lac objects are the most numerous class of extragalactic TeV-detected sources. One of the biggest difficulties in investigating their TeV emission is due to their limited number, since only 47 BL Lac objects are known to be TeV emitters. In this paper, we propose new criteria to select TeV BL Lac candidates based on infrared and X-ray observations. We apply our selection criteria to the BL Lac objects listed in the ROMA-BZCAT catalog, thereby identifying 41 potential TeV emitters. We then perform a search over a more extended sample combining the ROSAT bright source catalog and the WISE all-sky survey, revealing 54 additional candidates for TeV observations. Our investigation also led to a tentative classification of 16 unidentified X-ray sources as BL Lac candidates. This analysis provides new interesting BL Lac targets for future observations with ground-based Cherenkov telescopes.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2022

Lithium extraction composite for recovery of lithium from brines, and process of using said composition

A lithium extraction composite comprising: (i) a porous support and (ii) particles of a lithium-selective sorbent material coated on at least one surface of the support, wherein the support has a planar membrane, fiber (or rod), or tubular shape. A method for extracting and recovering a lithium salt from an aqueous solution by use of the above-described composition is also described, the method comprising (a) flowing the aqueous source solution through a first zone or over a first surface of the lithium extraction composite to result in selective lithium intercalation in the lithium-selective sorbent material in the first zone or first surface; and (b) simultaneously recovering lithium salt extracted in step (a) from said lithium-selective sorbent material by flowing an aqueous stripping solution through a second zone or over a second surface of the lithium extraction composite in which lithium ions from the first zone or first surface diffuse.

Bhave, Ramesh R.↗
DOE OSTI2019

Azimuthally Dependent Seismic-Wave Coherence at the Source Physics Experiment Large-N Array

Abstract We report on azimuthally dependent seismic scattering at the Source Physics Experiment (SPE) using the large-N array. The large-N array recorded the seismic wavefield produced by the SPE-5 buried chemical explosion, which occurred in April 2016 at the Nevada National Security Site, U.S.A. By selecting a subset of vertical-component geophones from the large-N array, we formed 10 linear arrays, with different nominal source–receiver azimuths as well as six 2D arrays. For each linear array, we analyze wavefield coherency as a function of frequency and interstation distance. For both the P arrival and post-P arrivals, the coherency is higher in the northeast propagation direction, which is consistent with the strike of the steeply dipping Boundary fault adjacent to the northwest side of the large-N array. Conventional array analysis using a suite of 2D arrays indicates that the presence of the fault may help explain the azimuthal dependence of the seismic-wave coherency for all wave types. This fault, which separates granite from alluvium, may be acting as a vertically oriented refractor and/or waveguide.

58 GEOSCIENCES↗
DOE OSTI2012

3 MV hypervelocity dust accelerator at the Colorado Center for Lunar Dust and Atmospheric Studies

A hypervelocity dust accelerator for studying micrometeorite impacts has been constructed at the Colorado Center for Lunar Dust and Atmospheric Studies (CCLDAS) at the University of Colorado. Based on the Max-Planck-Instituet fuer Kernphysik (MPI-K) accelerator, this accelerator is capable of emitting single particles of a specific mass and velocity selected by the user. The accelerator consists of a 3 MV Pelletron generator with a dust source, four image charge pickup detectors, and two interchangeable target chambers: a large high-vacuum test bed and an ultra-high vacuum impact study chamber. The large test bed is a 1.2 m diameter, 1.5 m long cylindrical vacuum chamber capable of pressures as low as 10{sup -7} torr while the ultra-high vacuum chamber is a 0.75 m diameter, 1.1 m long chamber capable of pressures as low as 10{sup -10} torr. Using iron dust of up to 2 microns in diameter, final velocities have been measured up to 52 km/s. The spread of the dust particles and the effect of electrostatic focusing have been measured using a long exposure CCD and a quartz target. Furthermore, a new technique of particle selection is being developed using real time digital filtering techniques. Signals are digitized and then cross-correlated with a shaped filter, resulting in a suppressed noise floor. Improvements over the MPI-K design, which include a higher operating voltage and digital filtering for detection, increase the available parameter space of dust emitted by the accelerator. The CCLDAS dust facility is a user facility open to the scientific community to assist with instrument calibrations and experiments.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2016

Ion selectivity of graphene nanopores

As population growth continues to outpace development of water infrastructure in many countries, desalination (the removal of salts from seawater) at high energy efficiency will likely become a vital source of fresh water. Due to its atomic thinness combined with its mechanical strength, porous graphene may be particularly well-suited for electrodialysis desalination, in which ions are removed under an electric field via ion-selective pores. Here, we show that single graphene nanopores preferentially permit the passage of K + cations over Cl - anions with selectivity ratios of over 100 and conduct monovalent cations up to 5 times more rapidly than divalent cations. Furthermore, the observed K + /Cl - selectivity persists in pores even as large as about 20 nm in diameter, suggesting that high throughput, highly selective graphene electrodialysis membranes can be fabricated without the need for subnanometer control over pore size.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Extreme-ultraviolet observations of global coronal wave rotation

We present evidence of global coronal wave rotation in EUV data from SOHO/EIT, STEREO/EUVI, and SDO/AIA. The sense of rotation is found to be consistent with the helicity of the source region (clockwise for positive helicity, anticlockwise for negative helicity), with the source regions hosting sigmoidal structures. We also study two coronal wave events observed by SDO/AIA where no clear rotation (or sigmoid) is observed. The selected events show supporting evidence that they all originate with flux rope eruptions. We make comparisons across this set of observations (both with and without clear sigmoidal structures). On examining the magnetic configuration of the source regions, we find that the nonrotation events possess a quadrupolar magnetic configuration. The coronal waves that do show a rotation originate from bipolar source regions.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2019

DeepWelding: a Deep Learning Enhanced Approach to GTAW Using Multi-source Sensing Images

Deep learning has great potential to reshape manufacturing industries. In this paper, we present DeepWelding, a novel framework that applies deep learning techniques to improve gas tungsten arc welding (GTAW) process monitoring and penetration detection using multi-source sensing images. The framework is capable of analyzing multiple types of optical sensing images synchronously and consists of three deep learning enhanced consecutive phases: image preprocessing, image selection, and weld penetration classification. Specifically, we adopted generative adversarial networks (pix2pix) for image denoising and classic convolutional neural networks (AlexNet) for image selection. Both pix2pix and AlexNet delivered satisfactory performance. However, five individual neural networks with heterogeneous architectures demonstrated inconsistent generalization capabilities in the classification phase when holding out multi-source images generated with specific experimental settings. Therefore, two ensemble methods combining multiple neural networks were designed to improve the model performance on unseen data collected from different experimental settings. In conclusion, we also found that the quality of model prediction was heavily influenced by the data stream collection environment. We think these findings are beneficial for the broad intelligent welding community.

42 ENGINEERING↗
DOE OSTI2021

Scalable multiphoton quantum metrology with neither pre- nor post-selected measurements

The quantum statistical fluctuations of electromagnetic fields establish a limit, known as the shot-noise limit, on the sensitivity of optical measurements performed with classical technologies. However, quantum technologies are not constrained by this shot-noise limit. In this regard, the possibility of using every photon produced by quantum sources of light to estimate small physical parameters, beyond the shot-noise limit, constitutes one of the main goals of quantum optics. Here, we experimentally demonstrate a scalable protocol for quantum-enhanced optical phase estimation across a broad range of phases, with neither pre- nor post-selected measurements. This is achieved through the efficient design of a source of spontaneous parametric downconversion in combination with photon-number-resolving detection. The robustness of two-mode squeezed vacuum states against loss allows us to outperform schemes based on N00N states, in which the loss of a single photon is enough to remove all phase information from a quantum state. In contrast to other schemes that rely on N00N states or conditional measurements, the sensitivity of our technique could be improved through the generation and detection of high-order photon pairs. This unique feature of our protocol makes it scalable. Furthermore, our work is important for quantum technologies that rely on multiphoton interference such as quantum imaging, boson sampling, and quantum networks.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Engineering Li/Na selectivity in 12-Crown-4–functionalized polymer membranes

Significance Lithium is a key ingredient in batteries, which are integral components of next-generation automobiles, airplanes, grid energy storage, and electronic devices. Unfortunately, lithium extraction from natural sources is laborious, slow, and costly, motivating the search for more efficient isolation techniques. While polymeric membranes could reduce the cost of lithium recovery, current membrane materials lack sufficient lithium-ion selectivity. To address this challenge, we introduce a class of polymeric membranes that incorporate ion binding sites, which significantly increases the transport selectivity of LiCl over NaCl. These studies provide guidelines and practical considerations for incorporating specific interactants into polymers that mediate selective ion transport.

36 MATERIALS SCIENCE↗
DOE OSTI2016

SPT-GMOS: A GEMINI/GMOS-SOUTH SPECTROSCOPIC SURVEY OF GALAXY CLUSTERS IN THE SPT-SZ SURVEY

We present the results of SPT-GMOS, a spectroscopic survey with the Gemini Multi-Object Spectrograph (GMOS) on Gemini South. The targets of SPT-GMOS are galaxy clusters identified in the SPT-SZ survey, a millimeter-wave survey of 2500 deg{sup 2} of the southern sky using the South Pole Telescope (SPT). Multi-object spectroscopic observations of 62 SPT-selected galaxy clusters were performed between 2011 January and 2015 December, yielding spectra with radial velocity measurements for 2595 sources. We identify 2243 of these sources as galaxies, and 352 as stars. Of the galaxies, we identify 1579 as members of SPT-SZ galaxy clusters. The primary goal of these observations was to obtain spectra of cluster member galaxies to estimate cluster redshifts and velocity dispersions. We describe the full spectroscopic data set and resulting data products, including galaxy redshifts, cluster redshifts, and velocity dispersions, and measurements of several well-known spectral indices for each galaxy: the equivalent width, W , of [O ii] λλ 3727, 3729 and H- δ , and the 4000 Å break strength, D4000. We use the spectral indices to classify galaxies by spectral type (i.e., passive, post-starburst, star-forming), and we match the spectra against photometric catalogs to characterize spectroscopically observed cluster members as a function of brightness (relative to m {sup ⋆}). Finally, we report several new measurements of redshifts for ten bright, strongly lensed background galaxies in the cores of eight galaxy clusters. Combining the SPT-GMOS data set with previous spectroscopic follow-up of SPT-SZ galaxy clusters results in spectroscopic measurements for >100 clusters, or ∼20% of the full SPT-SZ sample.

79 ASTRONOMY AND ASTROPHYSICS↗