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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 487 records · Page 27
All sourcesNASA NTRSDOE OSTI
NASA NTRS1990

The Advanced Solar Observatory

A conceptual plan for the development of a comprehensive long duration solar space observatory, The Advanced Solar Observatory (ASO) is described. The ASO is intended to provide solar astronomers with the observational power necessary to address fundamental problems relating to the solar convection zone and activity cycle; the thermal and nonthermal processes that control the transport of energy, mass, and magnetic flux in the solar atmosphere; the generation of the solar wind; and the dynamics of the inner heliosphere. The ASO concept encompasses three proposed Space Station-based instrument ensembles: (1) the High Resolution Telescope Cluster, which includes far ultraviolet, extreme ultraviolet, and X-ray telescopes; (2) the Pinhole/Occulter Facility, which includes Fourier transform and coded aperture hard X-ray and gamma ray telescopes and occulted ultraviolet and visible light coronagraphs; and (3) the High Energy Facility, which contains neutron, gamma ray, and low frequency radio spectrometers. Two other facilities, the Orbiting Solar Laboratory, and a package of Global Dynamics Instrumentation, will, with the Space Station ensembles, form a comprehensive capability for solar physics. The scientific program of the ASO, current instrument concepts for the Space Station based ASO instrument ensembles, and plans for their accommodation on the Space Station are described.

Walker, Arthur B. C., Jr.↗
DOE OSTI2025

Formation of Water Networks on Anionic Perylene

We present infrared photodissociation spectra of hydrated perylene anion clusters with up to four water molecules, as well as electronic structure calculations based on density functional theory. Water molecules form weak hydrogen bonds to the π system of the perylene anion. For clusters with more than one water molecule, water−water hydrogen bonds are formed, which generally appear to be stronger than water−π hydrogen bonds, especially for the trihydrate and tetrahydrate. The resulting water networks exist as water subclusters on the surface of the carbon frame of perylene. Here, we observe temperature-dependent dynamic effects, which highlight large amplitude motions of the water network and the shallowness of the potential energy surfaces governing the structures of these clusters.

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

Control of Permanent Porosity in Type 3 Porous Liquids via Solvent Clustering

Porous liquids (PLs) are an exciting new class of materials for carbon capture due to their high gas adsorption capacity and ease of industrial implementation. They are composed of sorbent particles suspended in a nonadsorbed solvent, forming a liquid with permanent porosity. While PLs have a vast number of potential compositions based on the number of solvents and sorbent materials available, most of the research has been focused on the selection of the sorbent rather than the solvent. Therefore, PL design criteria on the supramolecular structures of the solvent are explored to create a fundamental understanding of how the solvent enables PL formation for rapid discovery of new PL compositions. Atomistic molecular dynamics simulation of eight solvents with a range of molecular sizes, shapes, and intramolecular bonding was performed, identifying that the shape and size of molecular clusters formed in the solvent are the driving predictor of PL formation rather than the size of the individual solvent molecule. The results demonstrate a significant departure from common approaches to PL formation based on the steric exclusion of solvent molecules from the sorbent via the size of the pore aperture. A modeling and experimental validation study further supports these findings. In conclusion, through this computational material design study, a previously unexplored mechanism in PL formation, solvent–solvent clustering, is identified as a critical factor for the accelerated discovery of liquid phase carbon capture materials.

Carbon capture↗
DOE OSTI2026

Neural-network quantum states for the nuclear many-body problem

A long-standing goal of nuclear theory is to explain how the structure and dynamics of atomic nuclei and neutron-star matter emerge from the underlying interactions among protons and neutrons. Achieving this goal requires solving the nuclear quantum many-body problem with high accuracy across a wide range of length scales and density regimes. In this review, we discuss how artificial neural network representations of the nuclear many-body wave function have significantly extended the capabilities of continuum quantum Monte Carlo methods. In particular, neural network quantum states enable calculations of larger systems than were previously accessible and provide a flexible framework for capturing phenomena that challenge conventional approaches, including the emergence of nuclear clusters and superfluid phases in dense matter. We highlight recent applications to finite nuclei, infinite nuclear and neutron matter, and dynamical processes relevant to lepton-nucleus and nucleus-nucleus scattering. We also discuss conceptual and methodological connections with condensed matter physics, emphasizing developments in neural network quantum states that bridge strongly correlated systems across disciplines. Together, these developments demonstrate how neural-network methods open new avenues toward unified and accurate descriptions of nuclear structure, matter, and reactions.

Lovato, Alessandro [Argonne; TIFPA-INFN, Trento; V↗
NASA NTRSDate not supplied

Autonomous Nanosatellite Swarming (ANS) Using Radio Frequency and Optical Navigation

The Autonomous Nanosatellite Swarming (ANS) subsystem is a dynamics, guidance, navigation, and control software unit based on commercial-off-the-shelf avionics, which is distributed and deployed on a cluster of cooperative nanosatellites to enable future exploration missions to near-Earth objects (NEOs). ANS allows multiple nanosatellites to act together as a single large spacecraft through radio-frequency (RF) cross-links, optical navigation, and low-thrust control. In particular, ANS-equipped nanosatellites can utilize images of a NEO taken from multiple viewpoints to achieve stereo-vision capabilities and characterize the target body’s shape, gravity field, and dynamical properties. All this is enabled by the fusion of major advances to the state of the art in the astrodynamics of relative motion, RF and vision-based navigation, as well as low-thrust control.

Simone D'Amico↗
NASA NTRS1983

Redshifts of groups and clusters in the rich superclusters 1451+22 and 1615+43

Redshift measurements and finding charts are presented for galaxy clusters in the field of two rich, distant superclusters. Both systems are shown to have morphological and dynamical properties similar to the nearby superclusters, including small internal velocity dispersions and high density contrasts in redshift space. This data is consistent with two interpretations: either both superclusters are highly flattened systems with major axes close to the plane of the sky, or the observed velocity dispersions do not arise from unperturbed Hubble flow. If the latter explanation is correct, these radial velocity data are a powerful probe of the large scale matter density in the universe.

Ciardullo, R.↗
NASA NTRS1994

Study Of Heating Of The Base Region Of A Rocket

Report describes theoretical study of heating in base region of proposed rocket called "NLS 1.5 stage reference vehicle." Study employed approach based on computational fluid dynamics (CFD). Involved numerical simulations of flow field in base region and in main exhaust plume of cluster of six engines with heat shields.

Ascoli, Edward P.↗
NASA NTRS2004

Gas Density Discontinuities in Merging Clusters

In a number of galaxy clusters, Chandra has discovered a new phenomenon, the sharp gas density edges. Depending on the sign of the temperature jump across the edge, these features may either be bow shocks or cold fronts. While the merger origin of the bow shocks is unambiguous, what causes cold fronts is not entirely clear, as they are observed both in mergers and in relaxed clusters. The purpose of the study of A3376, an interesting cluster with density edges, is to understand the origin of cold fronts and to look for possible shocks. This cluster also has a radio halo, and comparison of an X-ray temperature map and radio image may shed light on the nature of the cluster radio halos, which is our secondary goal. The XMM data for A3376 have been obtained, processed and cleaned. Most of the preliminary analysis, including deriving a temperature map, is complete. We also have Chandra data for this cluster, and intend to compare and combine the two datasets. We are well underway toward determining the dynamical state of A3376 and the nature of its gas density discontinuities.

Mushotzky, Richard↗
NASA NTRS2005

Analysis of Aircraft Clusters to Measure Sector-Independent Airspace Congestion

The Distributed Air/Ground Traffic Management (DAG-TM) concept of operations* permits appropriately equipped aircraft to conduct Free Maneuvering operations. These independent aircraft have the freedom to optimize their trajectories in real time according to user preferences; however, they also take on the responsibility to separate themselves from other aircraft while conforming to any local Traffic Flow Management (TFM) constraints imposed by the air traffic service provider (ATSP). Examples of local-TFM constraints include temporal constraints such as a required time of arrival (RTA), as well as spatial constraints such as regions of convective weather, special use airspace, and congested airspace. Under current operations, congested airspace typically refers to a sector(s) that cannot accept additional aircraft due to controller workload limitations; hence Dynamic Density (a metric that is indicative of controller workload) can be used to quantify airspace congestion. However, for Free Maneuvering operations under DAG-TM, an additional metric is needed to quantify the airspace congestion problem from the perspective of independent aircraft. Such a metric would enable the ATSP to prevent independent aircraft from entering any local areas of congestion in which the flight deck based systems and procedures may not be able to ensure separation. This new metric, called Gaggle Density, offers the ATSP a mode of control to regulate normal operations and to ensure safety and stability during rare-normal or off-normal situations (e.g., system failures). It may be difficult to certify Free Maneuvering systems for unrestricted operations, but it may be easier to certify systems and procedures for specified levels of Gaggle Density that could be monitored by the ATSP, and maintained through relatively minor flow-rate (RTA type) restrictions. Since flight deck based separation assurance is airspace independent, the challenge is to measure congestion independent of sector boundaries. Figure 1 , reproduced from Ref. 1, depicts an example traffic situation. When the situation is analyzed by sector boundaries (left side of figure), a Dynamic Density metric would identify excessive congestion in the central sector. When the same traffic situation is analyzed independent of sector boundaries (right side of figure), a Gaggle Density metric would identify congestion in two dynamically defined areas covering portions of several sectors. The first step towards measuring airspace-independent congestion is to identify aircraft clusters, i.e., groups of closely spaced aircraft. The objective of this work is to develop techniques to detect and classify clusters of aircraft.

Bilimoria, Karl D.↗
DOE OSTI2024

Dynamic Activation of Single-Atom Catalysts by Reaction Intermediates: Conversion of Formic Acid on Rh/Fe 3 O 4 (001)

The stability and activity of supported single-atom catalysts (SACs) represent critical yet opposing factors limiting our ability to explore and exploit their unique properties. Here, this study demonstrates the operation of a switchable catalyst that is activated in the presence of surface intermediates and reverts back to a stable but inactive form when the reaction is completed. We employ atomically defined Rh-Fe 3 O 4 (001) catalysts to demonstrate how structurally stable Rh, bound in surface octahedral Fe sites, gets destabilized to form highly active Rh adatoms and small clusters. Conversion of formic acid, leading initially to surface formate and hydroxyl species, is employed as a model reaction to probe the dynamics of such processes. We find that surface hydroxyl recombination to water through the Mars van Krevelen mechanism reduces Rh coordination, triggering its conversion to active Rh adatoms. Since such lattice oxygen exchange is observed in many acid-base and redox chemistries, the process can be broadly applicable to controlling the activation of the range of SACs.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

High-accuracy method for modeling nucleation and growth of particles

State-of-the-art numerical models describing the kinetics of aerosol particle nucleation and growth from a cooling vapor primarily use a nodal method, in which particles that are smaller than the critical size are omitted from consideration because they are thermodynamically unfavorable. This omission is based on the assumption that most newly formed particles are above the critical size, so that subcritical-size particles are not important to take into account. Due to the nature of the nodal method, it suffers from numerical diffusion, which can cause an artificial broadening of the cluster size distribution leading to a significant overestimation of the number of large-size particles. To address these issues, we propose a more accurate numerical method that explicitly models particles of all sizes, and uses a special numerical scheme that substantially reduces the numerical diffusion and provides high solution accuracy and numerical stability. We extensively compare this novel method to the commonly used nodal solver of the general dynamic equation (GDE) for particle growth and demonstrate that it offers GDE solutions with higher accuracy with low numerical diffusion. Incorporating small subcritical clusters into the solution is crucial for: 1) more precise determination of the entire particle size distribution function and 2) wider applicability of the model to experimental studies with non-monotonic temperature variations leading to particle evaporation. The computational code implementing this numerical method in Python is available upon request.

42 ENGINEERING↗
NASA NTRS2019

Cluster Analysis of Spectroscopic Line Profiles and EUV Emission in RMHD Simulations and Observations of the Solar Atmosphere

Spatially-resolved observations from the IRIS, SDO/AIA, and other space mission and ground-based telescopes, coupled with realistic 3D RMHD simulations, are a powerful tool for analysis of processes in the solar atmosphere. To better understand the dynamical and thermodynamic properties in the simulation data and their connection to observations, it is essential to determine similarities in the behaviors of the synthesized and observed emission. However, the complexity of observational data and physical processes makes comparison of observations and modeling results difficult. In this work, we show the initial results of application of K-Means clustering (unsupervised machine learning) algorithm to two different problems: 1) recognition of the typical spectroscopic line profiles observed by IRIS during solar flares and their typical dynamic behavior; 2) recognition of shocks and heating events in synthetic AIA emission data obtained from StellarBox quiet-Sun simulations. The average silhouette width technique for the KMeans algorithm is utilized in different ways to obtain optimal numbers of clusters. We discuss application of the emission clustering to visualizations of the computational volume, understanding its evolutionary trends and behavior patterns, and inversion (reconstruction) of physical properties of the solar atmosphere from synthesizes emission data.

Sadykov, Viacheslav↗
NASA NTRS1986

Venus - Dead or alive?

In situ nightside electric field observations from the Pioneer Venus Orbiter have been interpreted as evidence of extensive lightning in the lower atmosphere of Venus. The scenario, including proposed evidence of clustering of lightning over surface highland regions, has encouraged the acceptance of currently active volcanic output as part of several investigations of the dynamics and chemistry of the atmosphere and the geology of the planet. However, the correlation between the 100-hertz electric field events attributed to lightning and nightside ionization troughs resulting from the interaction of the solar wind with the ionosphere indicates that the noise results from locally generated plasma instabilities and not from any behavior of the lower atmosphere. Furthemore, analysis of the spatial distribution of the noise shows that it is not clustered over highland topography, but rather occurs at random throughout the latitude and longitude regions sampled by the orbiter during the first 5 years of operation, from 1978 to 1984. Thus the electric field observations do not identify lightning and do not provide a basis for inferring the presence of currently active volcanic output. In the absence of known evidence to the contrary, it appears that Venus is no longer active.

Taylor, Harry A., Jr.↗
NASA NTRS1990

Origin and dynamics of emission line clouds in cooling flow environments

The author suggests that since clouds are born co-moving in a turbulent intra-cluster medium (ICM), the allowed parameter space can now be opened up to a more acceptable range. Large-scale motions can be driven in the central parts of cooling flows by a number of mechanisms including the motion of the central and other galaxies, and the dissipation of advected, focussed rotational and magnetic energy. In addition to the velocity width paradox, two other paradoxes (Heckman et al. 1989) can be solved if the ICM is turbulent. Firstly, the heating source for the emission line regions has always been puzzling - line luminosities are extremely high for a given (optical or radio) galaxy luminosity compared to those in non-cooling flow galaxies, therefore a mechanism peculiar to cooling flows must be at work. However most, if not all, previously suggested heating mechanisms either fail to provide enough ionization or give the wrong line ratios, or both. The kinetic energy in the turbulence provides a natural energy source if it can be efficiently converted to cloud heat. Researchers suggest that this can be done via magneto-hydrodynamic waves through plasma slip. Secondly, while the x ray observations indicate extended mass deposition, the optical line emission is more centrally concentrated. Since many of the turbulence-inducing mechanisms are strongest in the central regions of the ICM, so is the method of heating. In other words material is dropping out everywhere but only being lit up in the center.

Loewenstein, Michael↗
NASA NTRS2015

Presolar Materials in a Giant Cluster IDP of Probable Cometary Origin

Chondritic porous interplanetary dust particles (CP-IDPs) have been linked to comets by their fragile structure, primitive mineralogy, dynamics, and abundant interstellar materials. But differences have emerged between 'cometary' CP-IDPs and comet 81P/Wild 2 Stardust Mission samples. Particles resembling Ca-Al-rich inclusions (CAIs), chondrules, and amoeboid olivine aggregates (AOAs) in Wild 2 samples are rare in CP-IDPs. Unlike IDPs, presolar materials are scarce in Wild 2 samples. These differences may be due to selection effects, such as destruction of fine grained (presolar) components during the 6 km/s aerogel impact collection of Wild 2 samples. Large refractory grains observed in Wild 2 samples are also unlikely to be found in most (less than 30 micrometers) IDPs. Presolar materials provide a measure of primitive-ness of meteorites and IDPs. Organic matter in IDPs and chondrites shows H and N isotopic anomalies attributed to low-T interstellar or protosolar disk chemistry, where the largest anomalies occur in the most primitive samples. Presolar silicates are abundant in meteorites with low levels of aqueous alteration (Acfer 094 approximately 200 ppm) and scarce in altered chondrites (e.g. Semarkona approximately 20 ppm). Presolar silicates in minimally altered CP-IDPs range from approximately 400 ppm to 15,000 ppm, possibly reflecting variable levels of destruction in the solar nebula or statistical variations due to small sample sizes. Here we present preliminary isotopic and mineralogical studies of a very large CP-IDP. The goals of this study are to more accurately determine the abundances of presolar components of CP-IDP material for comparison with comet Wild 2 samples and meteorites. The large mass of this IDP presents a unique opportunity to accurately determine the abundance of pre-solar grains in a likely cometary sample.

Messenger, S.↗
NASA NTRS1994

The stellar population in the core of M15

The inner core of the globular cluster M15 within approximately 2 sec of the geometrical center has been explored with high-resolution images taken through several broad-band UV filter with the Faint Object Camera (FOC) on board the Hubble Space Telescope (HST). Approximately 210 stars in this region down to a 5 sigma detection limit of m(sub 220) = 21.5 were reliably identified and located on a UV - U color magnitude diagram for the first time. A majority of stars (about 70% of the total) observed this way lie above the expected main-sequence turn-off of this cluster and below the sparsely populated horizontal branch. The extension of the main sequence above the turn-off separates this population in two roughly equal components situated to the right and left of this line. Most of the former must be classical blue stragglers while the rest belong to a new, as yet unidentified, population of very blue stars. Possibilities include, but are not restricted to, well-mixed single stars, subdwarfs, and helium white dwarfs. Similar objects are also found just outside the core out to approximately 6 sec from the center, but the brighter, presumably more massive ones, are sharply confined to the core itself. The measured excess of bright blue stars and the relative deficiency of bright red giants in the core are consistent with the blue inward color gradient measured from the ground and imply that dynamical evolution can significantly affect the stellar population in the very dense central regions of a high-concentration globular cluster like M15.

De Marchi, Guido↗
NASA NTRSDate not supplied

Urban Air Mobility Airspace Dynamic Density

Effective flight planning requires information about a variety of potential threats, such as adverse weather or airspace restrictions, and about alternatives available if unforeseen events occur. Expected traffic along the route of flight is also essential to a safe outcome so that, for example, adequate fuel/energy supply can be loaded prior to flight. A dynamic density (DD) metric is introduced for the emerging urban air mobility (UAM) concept to predict airspace congestion that may lead to loss of separation between aircraft or less efficient operations. Using inspiration from dynamic density metric research for traditional air traffic management and a two-way highway analogy, we develop a dynamic density metric for a portion of airspace (aUAM corridor) that aggregates the impact from five factors: aircraft density, density of populous clusters, mean number of aircraft in populous clusters, mean distance between aircraft, and minimum distance between aircraft. This works describes our methodology, rationale, use cases, and visualization techniques to efficiently present the DD metric to an operator for informed decision making. We also present an approach for validating the metric. However, validation remains part of future work.

UAM↗