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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 1,603 records · Page 89
All sourcesNASA NTRSDOE OSTI
DOE OSTI2017

Spectroscopy of He–Ne afterglow plasma

The afterglow of pulsed low-current discharge in a He–Ne mixture is spectroscopically studied under conditions of competition between the processes of Ne{sub 2}{sup +} and HeNe{sup +} dissociative recombination with electrons, which are the sources of population of excited levels of neon atoms. The behavior of neon spectral lines in the wavelength range of 350–850 nm corresponding to the transitions from the levels of neon atoms of the 2p{sup 5}3p, 2p{sup 5}3d, 2p{sup 5}4p, 2p{sup 5}4d, 2p5{sup 5}s, 2p{sup 5}5d, 2p5{sup 6}s configurations are studied by the multichannel photoncounting method at electron density n{sub e} < 10{sup 11} cm{sup –3} and helium and neon pressures P{sub He} = 38 Torr and P{sub Ne} ≈ 10{sup -5}p{sub He} Distributions of recombination fluxes and population over excited states of the neon atom formed in the afterglow by homo- and heteronuclear ions are found. The data obtained show that vibrationally excited molecular ions make no noticeable contribution to the spectrum of decaying He–Ne plasma.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2025

Multi-Agent Hierarchical Deep Reinforcement Learning for HVAC Control With Flexible DERs

As electricity consumption in commercial and residential buildings continues to rise, reducing energy costs presents an increasing challenge. Heating, ventilating, and air-conditioning (HVAC) systems, which typically account for 40%-50% of a building's energy use, are prime targets for energy savings. Intelligent control of HVAC temperature through the exploitation of HVAC load flexibility brings significant potential to reduce energy consumption and electricity expenses. The nonlinear models of HVAC systems challenge traditional control methods, while the uncertainty introduced by HVAC load flexibility complicates distributed energy resource (DER) management using conventional optimal dispatch techniques. In response to these challenges, we propose a hierarchical multi-agent deep reinforcement learning (DRL) approach. The lower-level agents focus on balancing comfort and energy conservation, while the upper-level DRL agents optimize the use of DERs to reduce peak demand based on the control outcomes of the HVAC by the lower-level agents. Here, in the upper-level agents, we incorporate a multi-agent structure based on ensemble learning, which acts based on historical and current data without relying on precise load forecasting to address the delayed rewarding issue in DRL. This allows for the effective reduction of energy costs. The proposed method is tested using a real-world microgrid comprising 413 buildings in Southern California, and the results demonstrate that our approach can significantly reduce overall electricity bills while ensuring the comfort of consumers and residents.

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2015

Spatial distribution of the plasma parameters in the RF negative ion source prototype for fusion

A numerical model, based on the fluid plasma theory, has been used for description of the spatial distribution of the plasma parameters (electron density and temperature, plasma potential as well as densities of the three types of positive hydrogen ions) in the IPP prototype RF negative hydrogen ion source. The model covers the driver and the expansion plasma region of the source with their actual size and accounts for the presence of the magnetic filter field with its actual value and location as well as for the bias potential applied to the plasma grid. The obtained results show that without a magnetic filter the two 2D geometries considered, respectively, with an axial symmetry and a planar one, represent accurately the complex 3D structure of the source. The 2D model with a planar symmetry (where the E×B and diamagnetic drifts could be involved in the description) has been used for analysis of the influence, via the charged-particle and electron-energy fluxes, of the magnetic filter and of the bias potential on the spatial structure of the plasma parameters in the source. Benchmarking of results from the code to experimental data shows that the model reproduces the general trend in the axial behavior of the plasma parameters in the source.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2015

Preliminary result of P-wave speed tomography beneath North Sumatera region

The structure of P-wave speed beneath the North Sumatra region was determined using P-wave arrival times compiled by MCGA from time periods of January 2009 to December 2012 combining with PASSCAL data for February to May 1995. In total, there are 2,246 local earthquake events with 10,666 P-wave phases from 63 stations seismic around the study area. Ray tracing to estimate travel time from source to receiver in this study by applying pseudo-bending method while the damped LSQR method was used for the tomographic inversion. Based on assessment of ray coverage, earthquakes and stations distribution, horizontal grid nodes was set up of 30×30 km2 for inside the study area and 80×80 km2 for outside the study area. The tomographic inversion results show low Vp anomaly beneath Toba caldera complex region and around the Sumatra Fault Zones (SFZ). These features are consistent with previous study. The low Vp anomaly beneath Toba caldera complex are observed around Mt. Pusuk Bukit at depths of 5 km down to 100 km. The interpretation is these anomalies may be associated with ascending hot materials from subduction processes at depths of 80 km down to 100 km. The obtained Vp structure from local tomography will give valuable information to enhance understanding of tectonic and volcanic in this study area.

58 GEOSCIENCES↗
DOE OSTI2017

Titanium Alloys Thin Sheet Welding with the Use of Concentrated Solar Energy

The present study deals with the welding of titanium alloys thin sheets 1.3 mm thick, with the use of concentrated solar energy. The experimental part of the work took place at a medium size solar furnace at the installation of the Centre National de la Recherche Scientifique, at Odeillo, in Southern France, where similar and dissimilar defect-free welds of titanium Grades 4 and 6 were achieved, in the butt joint configuration. After the determination of the appropriate welding conditions, the optimum welded structures were examined and characterized microstructurally, by means of light optical microscopy, scanning electron microscopy, and microhardness testing. In addition, test pieces extracted from the weldments were tested under uniaxial tensile loading aiming to the estimation of the strength and the ductility of the joint. The analysis of the experimental results and the recorded data led to the basic concluding remarks which demonstrate increased hardness distribution inside the fusion area and severe loss of ductility, but adequate yield and tensile strength of the welds.

36 MATERIALS SCIENCE↗
DOE OSTI2023

In-depth analysis on parallel processing patterns for high-performance Dataframes

The Data Science domain has expanded monumentally in both research and industry communities during the past decade, predominantly owing to the Big Data revolution. Artificial Intelligence (AI) and Machine Learning (ML) are bringing more complexities to data engineering applications, which are now integrated into data processing pipelines to process terabytes of data. Typically, a significant amount of time is spent on data preprocessing in these pipelines, and hence improving its efficiency directly impacts the overall pipeline performance. The community has recently embraced the concept of Dataframes as the de-facto data structure for data representation and manipulation. However, the most widely used serial Dataframes today (R, pandas) experience performance limitations while working on even moderately large data sets. We believe that there is plenty of room for improvement by taking a look at this problem from a high-performance computing point of view. In a prior publication, we presented a set of parallel processing patterns for distributed dataframe operators and the reference runtime implementation, Cylon. In this paper, we are expanding on the initial concept by introducing a cost model for evaluating the said patterns. Furthermore, we evaluate the performance of Cylon on the ORNL Summit supercomputer.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2016

Anion ordering, magnetic structure and properties of the vacancy ordered perovskite Ba{sub 3}Fe{sub 3}O{sub 7}F

This article describes a detailed investigation of the crystallographic and magnetic structure of perovskite type Ba{sub 3}Fe{sub 3}O{sub 7}F by a combined analysis of X-ray and neutron powder diffraction data. Complete ordering of vacancies within the perovskite lattice could be confirmed. In addition, the structure of the anion sublattice was studied by means of the valence bond method, which suggested partial ordering of the fluoride ions on two of the six crystallographically different anion sites. Moreover, the compound was found to show G-type antiferromagnetic ordering of Fe moments, in agreement with magnetometric measurements as well as previously recorded {sup 57}Fe Mössbauer spectroscopy data. - Graphical abstract: The vacancy and anion ordered structure of Ba{sub 3}Fe{sub 3}O{sub 7}F is described together with its magnetic properties. - Highlights: • Ba{sub 3}Fe{sub 3}O{sub 7}F possesses a unique vacancy order not found for other perovskite type compounds. • The valence bond method was used to locate oxide and fluoride ions. • Fluoride ions are distributed only on two of the six anion sites in Ba{sub 3}Fe{sub 3}O{sub 7}F. • The compound shows G-type antiferromagnetic ordering of magnetic moments. • The magnetic structure could be refined in one of the maximal magnetic subgroups of the nuclear structure.

36 MATERIALS SCIENCE↗
DOE OSTI2016

Installing heterobimetallic cobalt–aluminum single sites on a metal organic framework support

Here, a heterobimetallic cobalt-aluminum complex was immobilized onto the metal organic framework NU-1000 using a simple solution-based deposition procedure. Characterization data are consistent with a maximum loading of a single Co-Al complex per Zr 6 node of NU-1000. Furthermore, the data support that the Co-Al bimetallic complex is evenly distributed throughout the NU-1000 particle, binds covalently to the Zr6 nodes, and occupies the NU-1000 apertures with the shortest internode distances (~8.5 Å). Heating the anchored Co-Al complex on NU-1000 at 300 °C for 1 h in air completely removes the organic ligand of the complex without affecting the structural integrity of the MOF support. We propose that a Co-Al oxide cluster is formed in place of the anchored complex in NU-1000 during heating. Collectively, the results suggest that well-defined heterobimetallic complexes can be effective precursors for installing two different metals simultaneously onto a MOF support. The CoAl-functionalized NU-1000 samples catalyze the oxidation of benzyl alcohol to benzaldehyde with tert -butyl hydroperoxide as a stoichiometric oxidant. Density functional theory calculations were performed to elucidate the detailed structures of the Co-Al active sites on the Zr 6 -nodes, and a Co-mediated catalytic mechanism is proposed.

36 MATERIALS SCIENCE↗
DOE OSTI2026

Cooperative Lanthanide Solvation in an Ionic Liquid for Critical Materials Separations

Effectively separating critical materials, including intra-lanthanide separations, is crucial for meeting growing application demands. Liquid–liquid extraction (LLE) is the industry standard for lanthanide separations, where the selectivity can depend on small changes in metal coordination. In this work, we investigate representative lanthanide Eu coordination with a neutral malonamide extractant in an imidazolium bistriflimide ionic liquid (IL) solvent. Through systematic titrations of the water and extractant and under extraction conditions, we observe surprising cooperative Eu solvation with the IL anion and extractant. Time-resolved fluorescence spectroscopy measurements show strong extractant coordination in water-saturated IL. Lifetime measurements show no water coordination, and extended X-ray fine structure spectroscopy data provide a coordination number of 10. Molecular dynamics simulations confirm this coordination number and reveal IL anion coordination in the final Eu complex, even though it is ordinarily a significantly weaker ligand compared to water. The lack of water in the final extracted complex and IL anion coordination potentially explain the increased extraction in LLE systems using ILs, as evidenced by higher distribution ratios for cation exchange extraction, despite the energetic cost of cation transfer to the aqueous phase. These results highlight the opportunities for tuning metal coordination to drive extraction in unique solvent systems.

Carr, Amanda J.↗
DOE OSTI2024

Achieving precise multiparameter measurements with distributed optical fiber sensor using wavelength diversity and deep neural networks

The development of advanced distributed optical fiber sensing systems that are capable of performing accurate and spatially resolved multiparameter measurements is of great interest to a wide range of scientific and industrial applications. Here, in this paper, we propose and experimentally demonstrate a wavelength diversity based advanced distributed optical fiber sensor system to accomplish multiparameter sensing while greatly enhancing measurement accuracy. A suite of deep neural network (DNN) algorithms are developed and verified for data denoising, rapid Brillouin frequency shift estimation, and vibration data event classification. As a proof-of-concept, we demonstrate the effectiveness of the proposed advanced wavelength diversity distributed fiber sensor system assisted by DNN for simultaneous, independent measurements of static strain, temperature, and acoustic vibrations over a 25 km long sensing fiber at 3 m spatial resolution. These results suggest the potential for an intelligent multiparameter monitoring system with enhanced performance in advanced structural health monitoring applications.

47 OTHER INSTRUMENTATION↗
DOE OSTI2016

Real-time microstructure imaging by Laue microdiffraction: A sample application in laser 3D printed Ni-based superalloys

Synchrotron-based Laue microdiffraction has been widely applied to characterize the local crystal structure, orientation, and defects of inhomogeneous polycrystalline solids by raster scanning them under a micro/nano focused polychromatic X-ray probe. In a typical experiment, a large number of Laue diffraction patterns are collected, requiring novel data reduction and analysis approaches, especially for researchers who do not have access to fast parallel computing capabilities. In this article, a novel approach is developed by plotting the distributions of the average recorded intensity and the average filtered intensity of the Laue patterns. Visualization of the characteristic microstructural features is realized in real time during data collection. As an example, this method is applied to image key features such as microcracks, carbides, heat affected zone, and dendrites in a laser assisted 3D printed Ni-based superalloy, at a speed much faster than data collection. Such analytical approach remains valid for a wide range of crystalline solids, and therefore extends the application range of the Laue microdiffraction technique to problems where real-time decision-making during experiment is crucial (for instance time-resolved non-reversible experiments).

36 MATERIALS SCIENCE↗
DOE OSTI2016

Planck intermediate results: XLI. A map of lensing-induced B -modes

The secondary cosmic microwave background (CMB) B-modes stem from the post-decoupling distortion of the polarization E-modes due to the gravitational lensing effect of large-scale structures. These lensing-induced B-modes constitute both a valuable probe of the dark matter distribution and an important contaminant for the extraction of the primary CMB B-modes from inflation. Planck provides accurate nearly all-sky measurements of both the polarization E-modes and the integrated mass distribution via the reconstruction of the CMB lensing potential. By combining these two data products, we have produced in this paper an all-sky template map of the lensing-induced B-modes using a real-space algorithm that minimizes the impact of sky masks. The cross-correlation of this template with an observed (primordial and secondary) B-mode map can be used to measure the lensing B-mode power spectrum at multipoles up to 2000. In particular, when cross-correlating with the B-mode contribution directly derived from the Planck polarization maps, we obtain lensing-induced B-mode power spectrum measurement at a significance level of 12σ, which agrees with the theoretical expectation derived from the Planck best-fit Λ cold dark matter model. This unique nearly all-sky secondary B-mode template, which includes the lensing-induced information from intermediate to small (10 ≲ ℓ ≲ 1000) angular scales, is delivered as part of the Planck 2015 public data release. Finally, it will be particularly useful for experiments searching for primordial B-modes, such as BICEP2/Keck Array or LiteBIRD, since it will enable an estimate to be made of the lensing-induced contribution to the measured total CMB B-modes.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2014

Triplet correlation functions in liquid water

Triplet correlations have been shown to play a crucial role in the transformation of simple liquids to anomalous tetrahedral fluids [M. Singh, D. Dhabal, A. H. Nguyen, V. Molinero, and C. Chakravarty, Phys. Rev. Lett. 112, 147801 (2014)]. Here we examine triplet correlation functions for water, arguably the most important tetrahedral liquid, under ambient conditions, using configurational ensembles derived from molecular dynamics (MD) simulations and reverse Monte Carlo (RMC) datasets fitted to experimental scattering data. Four different RMC data sets with widely varying hydrogen-bond topologies fitted to neutron and x-ray scattering data are considered [K. T. Wikfeldt, M. Leetmaa, M. P. Ljungberg, A. Nilsson, and L. G. M. Pettersson, J. Phys. Chem. B 113, 6246 (2009)]. Molecular dynamics simulations are performed for two rigid-body effective pair potentials (SPC/E and TIP4P/2005) and the monatomic water (mW) model. Triplet correlation functions are compared with other structural measures for tetrahedrality, such as the O–O–O angular distribution function and the local tetrahedral order distributions. In contrast to the pair correlation functions, which are identical for all the RMC ensembles, the O–O–O triplet correlation function can discriminate between ensembles with different degrees of tetrahedral network formation with the maximally symmetric, tetrahedral SYM dataset displaying distinct signatures of tetrahedrality similar to those obtained from atomistic simulations of the SPC/E model. Triplet correlations from the RMC datasets conform closely to the Kirkwood superposition approximation, while those from MD simulations show deviations within the first two neighbour shells. The possibilities for experimental estimation of triplet correlations of water and other tetrahedral liquids are discussed.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2016

The evaluation of the earthquake hazard using the exponential distribution method for different seismic source regions in and around Ağrı

The aim of this study; were determined of the earthquake hazard using the exponential distribution method for different seismic sources of the Ağrı and vicinity. A homogeneous earthquake catalog has been examined for 1900-2015 (the instrumental period) with 456 earthquake data for Ağrı and vicinity. Catalog; Bogazici University Kandilli Observatory and Earthquake Research Institute (Burke), National Earthquake Monitoring Center (NEMC), TUBITAK, TURKNET the International Seismological Center (ISC), Seismological Research Institute (IRIS) has been created using different catalogs like. Ağrı and vicinity are divided into 7 different seismic source regions with epicenter distribution of formed earthquakes in the instrumental period, focal mechanism solutions, and existing tectonic structures. In the study, the average magnitude value are calculated according to the specified magnitude ranges for 7 different seismic source region. According to the estimated calculations for 7 different seismic source regions, the biggest difference corresponding with the classes of determined magnitudes between observed and expected cumulative probabilities are determined. The recurrence period and earthquake occurrence number per year are estimated of occurring earthquakes in the Ağrı and vicinity. As a result, 7 different seismic source regions are determined occurrence probabilities of an earthquake 3.2 magnitude, Region 1 was greater than 6.7 magnitude, Region 2 was greater than than 4.7 magnitude, Region 3 was greater than 5.2 magnitude, Region 4 was greater than 6.2 magnitude, Region 5 was greater than 5.7 magnitude, Region 6 was greater than 7.2 magnitude, Region 7 was greater than 6.2 magnitude. The highest observed magnitude 7 different seismic source regions of Ağrı and vicinity are estimated 7 magnitude in Region 6. Region 6 are determined according to determining magnitudes, occurrence years of earthquakes in the future years, respectively, 7.2 magnitude was in 158 years, 6.7 magnitude was in 70 years, 6.2 magnitude was in 31 years, 5.7 magnitude was in 13 years, 5.2 magnitude was in 6 years.

58 GEOSCIENCES↗
DOE OSTI2021

The Coordination Chemistry and Stoichiometry of Extracted Diglycolamide Complexes of Lanthanides in Extraction Chromatography Materials

Industrial rare earth element (REE) separations predominantly utilize solvent extraction processes tailored toward conventional resources such as bastnäsite, monazite, and ion adsorption clays. Advances in diglycolamide (DGA) chemistry have shown effective extraction characteristics for REE separations. However, limitations associated with traditional DGA solvent extraction techniques, such as third-phase formation and gelling, have hindered commercial viability. By supporting DGA extractants on porous resins such as polystyrene divinyl benzene (PS-DVB), the desirable combination of solvent extraction selectivity and ease of operation of sorbent columns can be achieved. To design a low-cost model for such solid-supported DGAs, extraction characteristics as influenced by the underlying coordination chemistry must be explored to achieve efficient functional systems. Within this study, we report novel DGA resin materials, each incorporating one of the DGAs N,N,N’,N’-tetra-(1-octyl)-3-oxapentane-1,5-diamide (TODGA), N,N'-dimethyl-N,N'-dioctyl-3-oxapentane-1,5-diamide (DMDODGA), and 2,2'-oxybis(1-(3-(((2-ethylhexyl)thio)methyl)-4-methylpyrrolidin-1-yl)ethan-1-one) (DEHPDGA). The affinity of DGAs across the lanthanide (Ln) series was evaluated for both hydrochloric acid and nitric acid media with varying Ln feed concentrations to study distribution ratios and loading characteristics. Focusing on dysprosium, extended X-Ray Absorption Fine Structure (EXAFS) and density functional theory (DFT) calculations were also utilized to explore coordination chemistry and their effects on ligand performance. The general trend for both acid media resulted in DMDODGA having the highest extraction strength of all three DGAs at varying acid concentrations. Coordination-chemistry analysis supported by loading data, DFT calculations, and EXAFS results under forced loading conditions posited less than the expected 3:1 ligand-to-metal coordination.

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

Herschel OBSERVATIONS OF DUST AROUND THE HIGH-MASS X-RAY BINARY GX 301-2

We aim at characterizing the structure of the gas and dust around the high-mass X-ray binary GX 301-2, a highly obscured X-ray binary hosting a hypergiant (HG) star and a neutron star, in order to better constrain its evolution. We used Herschel PACS to observe GX 301-2 in the far infrared and completed the spectral energy distribution of the source using published data or catalogs from the optical to the radio range (0.4 to 4 × 10{sup 4} μm). GX 301-2 is detected for the first time at 70 and 100 μm. We fitted different models of circumstellar (CS) environments to the data. All tested models are statistically acceptable, and consistent with an HG star at ∼3 kpc. We found that the addition of a free-free emission component from the strong stellar wind is required and could dominate the far-infrared flux. Through comparisons with similar systems and discussion on the estimated model parameters, we favor a disk-like CS environment of ∼8 AU that would enshroud the binary system. The temperature goes down to ∼200 K at the edge of the disk, allowing for dust formation. This disk is probably a rimmed viscous disk with an inner rim at the temperature of the dust sublimation temperature (∼1500 K). The similarities between the HG GX 301-2, B[e] supergiants, and the highly obscured X-ray binaries (particularly IGR J16318-4848) are strengthened. GX 301-2 might represent a transition stage in the evolution of massive stars in binary systems, connecting supergiant B[e] systems to luminous blue variables.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2015

DEBRIS DISTRIBUTION IN HD 95086—A YOUNG ANALOG OF HR 8799

HD 95086 is a young early-type star that hosts (1) a 5 M{sub J} planet at the projected distance of 56 AU revealed by direct imaging, and (2) a prominent debris disk. Here we report the detection of 69 μm crystalline olivine feature from the disk using the Spitzer/MIPS-SED data covering 55-95 μm. Due to the low resolution of the MIPS-SED mode, this feature is not spectrally resolved, but is consistent with the emission from crystalline forsterite contributing ∼5% of the total dust mass. We also present detailed analysis of the disk spectral energy distribution and re-analysis of resolved images obtained by Herschel. Our results suggest that the debris structure around HD 95086 consists of a warm (∼175 K) belt, a cold (∼55 K) disk, and an extended disk halo (up to ∼800 AU), and is very similar to that of HR 8799. We compare the properties of the three debris components, and suggest that HD 95086 is a young analog of HR 8799. We further investigate and constrain single-planet, two-planet, three-planet, and four-planet architectures that can account for the observed debris structure and are compatible with dynamical stability constraints. We find that equal-mass four-planet configurations of geometrically spaced orbits, with each planet of mass ∼ 5 M{sub J} , could maintain the gap between the warm and cold debris belts, and also be just marginally stable for timescales comparable to the age of the system.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2019

MAUS: the MICE analysis user software

The Muon Ionization Cooling Experiment (MICE) collaboration has developed the MICE Analysis User Software (MAUS) to simulate and analyze experimental data. It serves as the primary codebase for the experiment, providing for offline batch simulation and reconstruction as well as online data quality checks. The software provides both traditional particle-physics functionalities such as track reconstruction and particle identification, and accelerator physics functions, such as calculating transfer matrices and emittances. The code design is object orientated, but has a top-level structure based on the Map-Reduce model. This allows for parallelization to support live data reconstruction during data-taking operations. MAUS allows users to develop in either Python or C++ and provides APIs for both. Various software engineering practices from industry are also used to ensure correct and maintainable code, including style, unit and integration tests, continuous integration and load testing, code reviews, and distributed version control. The software framework and the simulation and reconstruction capabilities are described.

47 OTHER INSTRUMENTATION↗