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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 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Physical properties, internal structure, and the three‐dimensional petrography of CI chondrites

physical properties and the nature of their breccation, we investigated nine samples of the Ivuna and Orgueil CI chondrites ranging in size from 1 mm to 4 cm in approximate diameter. The combined mass of unique material investigated in this work is 113 g. For our investigations, we use ideal gas pycnometry, 3-D laser scanning, x-ray computed microtomography (μCT), and accompanying digital data extraction techniques. We found that the bulk density of the samples ranged from 1.61 to 2.10 g cm −3 . Larger samples tend to have a lower bulk density. Grain density (ranging from 2.44 to 2.55 g cm −3 ) is significantly less variable than the bulk density in our samples and the quantity of porosity (ranging from 14.6% to 33.8%) is the dominant factor in determining the bulk density of CI chondrite material. Our μCT results show that the visible porosity across all sizes of our CI chondrite samples is in the form of cracks, but these cracks can account for less than two-thirds of the porosity in the CI chondrites. Other porosity is not visible, even at μCT resolutions of 2.7 μm voxel edge −1 and we conclude that it is sub-micron in nature. It is not clear if the cracks seen in our samples are indigenous to the chondrites or are a result of terrestrial processes. We also find that the CI chondrites are excellent examples of the fractal-like nature of brecciation, where clasts can be observed at all scales we imaged. The breccias are composed of sub-equant-shaped and sub-rounded-textured clasts like melt-free impact breccias on other solar system bodies. From our μCT volume and digital data extraction, we determine that the Ivuna CI chondrite breccia is organized: the mostly sub-equant clasts within our ~2 cm chunk of Ivuna have a mean diameter of 1.33 mm and their aligned longest axes define a lineation structure. We speculate that the lineation was imparted after fragmentation of the clasts by slight shear on the parent asteroid which could be the result of seismic-related granular flow or mild non-axial impact-related compaction. These data will help to place returned asteroidal material from asteroids 162173 Ryugu and 101955 Bennu and the CI chondrites into a mutual geological context.

CI chondrite↗
DOE OSTI2025

BULKI-Store v0.3.2

BULKI-Store is a distributed object storage system optimized for high-performance computing environments. Built with a Rust core and Python bindings, it efficiently manages scientific and machine learning datasets across HPC clusters. The system employs a client-server architecture with MPI integration, enabling seamless scaling on supercomputers like Perlmutter. BULKI-Store's object-oriented approach provides intuitive data organization with rich metadata support, contrasting with traditional file-based solutions. Key optimizations include selective checkpoint loading, unified checkpoint files, and object chunking for large data transfers. For machine learning workloads, BULKI-Store offers advantages through fine-grained access patterns, dynamic data sharing between training instances, and reduced memory pressure. Memory management features include strategic Python GC calls, minimized data copies, and batch processing capabilities. The system leverages Rayon's thread pool for asynchronous data prefetching and supports multiple CPU architectures (ARM64, x86, AMD, RISC-V). By combining performance optimizations with developer-friendly APIs, BULKI-Store addresses the complex data management challenges of modern HPC applications while maintaining compatibility across heterogeneous computing environments.

Zhang, Wei [Lawrence Berkeley National Laboratory ↗
DOE OSTI2026

V-HAMSTeR v1.0.0

V-HAMSTeR is a bioinformatics software tool designed to predict the hosts of viruses directly from genomic sequences. It can be used by researchers to predict animal, prokaryotic, plant, protist or fungal viral hosts including viruses that may be fragmented or discovered in environmental metagenomic datasets. Features & Uses: The software employs a novel dual-stream deep learning architecture that dynamically fuses implicit sequence embeddings from a genomic foundation model with 13 explicit, handcrafted biological features (e.g., coding density and strand switch rates). To ensure maximum reliability, V=HAMSTeR deploys a 5-fold deep ensemble calibrated via Joint Temperature Scaling, providing users with statistically rigorous confidence probabilities. It also features an automated sequence chunking and mean-pooling module to seamlessly process variable-length contigs. Advantages Over Similar Technologies: Existing tools (e.g., IPEV, RNAVirHost) typically rely on either basic k-mers or isolated neural networks. V-HAMSTeR's hybrid architecture captures both broad genomic context and specific biological motifs that standalone foundation models often miss. Furthermore, unlike competitor tools that struggle with incomplete data or exhibit extreme overconfidence, V-HAMSTeR is explicitly benchmarked and mathematically calibrated for fragmented assemblies (1kb–10kb). This makes it uniquely robust, accurate, and trustworthy for the messy reality of real-world environmental viromics.

Grigson, Susie [Lawrence Berkeley National Laborat↗
DOE OSTI2024

Globus service enhancements for exascale applications and facilities

Many extreme-scale applications require the movement of large quantities of data to, from, and among leadership computing facilities, as well as other scientific facilities and the home institutions of facility users. These applications, particularly when leadership computing facilities are involved, can touch upon edge cases (e.g., terabyte files) that had not been a focus of previous Globus optimization work, which had emphasized rather the movement of many smaller (megabyte to gigabyte) files. We report here on how automated client-driven chunking can be used to accelerate both the movement of large files and the integrity checking operations that have proven to be essential for large data transfers. In conclusion, we present detailed performance studies that provide insights into the benefits of these modifications in a range of file transfer scenarios.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2026

Communications Reliability for Vehicle Grid Integration

Electric Vehicles (EVs) adoption rate has been steadily increasing in the US leading to a growing number of charging stations including faster DC (Direct Current) chargers and slower Level 1 and Level 2 AC (Alternating Current) chargers. This increase in demand for electricity is further exacerbated by recent developments in Artificial Intelligence (AI) technology, advanced manufacturing, and digitization. These factors will require electric utilities to upgrade their infrastructure to keep up with the increasing electrical demand (especially during peak hours). An easy way to counteract the need for these upgrades is to shift a major chunk of active charge sessions (durations where there is energy transfer from charger to EV's propulsion battery) to off-peak hours thereby flattening the load curve and making the infrastructure more resilient. This concept is known as Smart Charge Management (SCM). EV owners also benefit from SCM since it lowers their charging costs and consequently their transportation costs by prioritizing charging during off-peak hours. SCM takes advantage of EV's capability to act as a controllable load or DER (Distributed Energy Resource). This report summarizes the reliability analysis performed on the communication required for two of these SCM use-cases. This analysis only focuses on SCM strategies for unidirectional charging (energy transfer from EVSE to EV or V1G) and not bidirectional charging.

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2026

Knowledge Graph for End-to-End Traceability of an Integrated Human-Earth System Model

Integrated human-Earth system models inform energy-water-land system dynamics and policies, yet their results are difficult to trace through input-data, model structure, scenario configurations, and solved outputs. Because this information is siloed across disconnected artifacts, process-based IAMs have historically lacked a unified, queryable representation. Such lack of traceability prevents researchers from systematically isolating the multi-sector drivers of complex outcomes (such as tracing water-scarcity results back to distant energy-system dynamics) or conducting holistic uncertainty attribution across hundreds of interacting parameters. To address this concern, our work documents the software engineering process of a knowledge graph that unifies these four layers for the Global Change Analysis Model (GCAM-USA_Reference scenario, GCAM v9.1). The graph was built as a relational property graph in DuckDB from the run’s own artifacts: the input-preparation dependency map (gcamdata chunk map), the model’s XML input files, the run configuration, and the results database (BaseX), successfully mapping the model’s declared structure. The resulting graph comprises 204,321 nodes and 1,687,814 edges across 16 node types and 15 edge types, with approximately 16.3 million time-series values stored separately to maintain structural efficiency. To ensure representation fidelity, every edge carries an epistemic-status annotation recording the warrant for the relationship (structural, provenance, dependency, or model-derived), and a machine-readable provenance ledger classifying the origin of every schema element. Evaluation against a fixed five-benchmark suite with locked baselines reports zero structural orphans, zero dangling edge endpoints, and 100% of output-producing technologies traceable to raw input files. Two interactive interfaces present the graph, including a serverless browser application built on DuckDB-Wasm. By establishing the first end-to-end provenance framework for an IAM, this work enables researchers and scientists to systematically audit complex policy scenarios, debug model structures, and trace policy-relevant outputs to their data origins in real time.

Artifical Intelligence↗
NASA NTRS1973

Heating of food in modified atmospheres

Food heating tests were conducted with two model foods; a Carnation turkey salad sandwich spread and frankfurter chunks in a sauce of water and agar. For the first series of tests comparing heating in five different atmospheres, the atmospheres were: (1) air at atmospheric pressure, (2) air at 5 psia, (3) helium at 5 psia, (4) oxygen-nitrogen mixture at 5 psia, and (5) oxygen-helium mixture at 5 psia. No significant differences in heating rates were caused by varying the atmosphere. Initial food temperatures were varied in the next series of tests. Heating times were found to increase with decreasing initial temperatures. There were also differences in heating times between the two foods used.

Sweat, V. E.↗
NASA NTRS1974

Preliminary report of mineralogical and petrographic study of the Luna 16 lunar surface material sample

Unsorted powder and grains larger than 0.5 mm from the L-16-19-118 lunar sample consisted of eight basaltic fragments, four fragments of breccias (of which one was quite light), one white grain (maskelynite), one chondrule, and slagged dark partially glassy chunks. The mineralogical composition of all rounded particles led to the assumption that they are all of lunar origin; but their presence in the regolith indicates formation of chondrulic meteorites. The existence of several grains of pyroxene coated with a thin glassy film merits attention.

Christophe-Michel-levi, M.↗
NASA NTRS1976

Radar observations at 3.5 and 12.6 cm wavelength of asteroid 433 Eros

A study of the asteroid 433 Eros using 3.5 and 12.6 cm radar waves indicates that the surface is very much rougher than any planetary or lunar surface observed by this method. A surface completely covered with sharp edges, pits, subsurface holes, or embedded chunks with scale sizes on the order of our wavelengths seems to be indicated. A model based on a rough rotating triaxial ellipsoid having radii in the rotation equator of 18.6 and 7.9 km agrees well with our data, although a strong wobble in the apparent center frequency of the spectra as rotation progresses indicates that one side may be more reflective than the other, or more likely, that the projected axis of rotation does not equally divide the projected area.

Jurgens, R. F.↗
NASA NTRS1981

Producing silicon continuously

Fluid-bed vaporization followed by chemical vapor deposition generates large, semiconductor-grade silicon particles. Method is economical, high-volume alternative to conventional batch-processing methods. Harvested chunks, extracted in cyclone separator, are about 0.5 to 1.3 centimeters in diameter. Process is not limited to polymer feedstock; it utilizes any halosilane intermediate used in silicon production.

Ingle, W. M.↗
NASA NTRS1980

The narrow rings of Jupiter, Saturn and Uranus

The origin of the newly discovered narrow ring systems around Jupiter, Saturn and Uranus is considered. It is pointed out that both the Uranian and Jovian ring systems have mean orbital radii of 1.8 planetary radii and lie within the Roche zones of their respective planets, and it is suggested that the Jovian ring is the product of the disintegration of a satellite that entered the Roche zone, and that large numbers of small particles are now in horseshoe orbits about the Lagrangian equilibrium points of the remnant chunks. Analysis of the path of a ring particle in a horseshoe orbit is shown to result in ring structures in agreement with those observed for the circular rings of Jupiter and the highly eccentric ring of Uranus. The stability of these ring systems is then considered, and it is suggested that the F ring of Saturn, which lies outside the Roche zone, represents primordial matter not yet accreted by small satellites just inside the Mimas first-order resonances.

Dermott, S. F.↗
NASA NTRS1981

Low cost solar aray project: Experimental process system development unit for producing semiconductor-grade silicon using the silane-to-silicon process

This phase consists of the engineering design, fabrication, assembly, operation, economic analysis, and process support R&D for an Experimental Process System Development Unit (EPSDU). The mechanical bid package was issued and the bid responses are under evaluation. Similarly, the electrical bid package was issued, however, responses are not yet due. The majority of all equipment is on order or has been received at the EPSDU site. The pyrolysis/consolidation process design package was issued. Preparation of process and instrumentation diagram for the free-space reactor was started. In the area of melting/consolidation, Kayex successfully melted chunk silicon and have produced silicon shot. The free-space reactor powder was successfully transported pneumatically from a storage bin to the auger feeder twenty-five feet up and was melted. The fluid-bed PDU has successfully operated at silane feed concentrations up to 21%. The writing of the operating manual has started. Overall, the design phase is nearing completion.

Source record↗
NASA NTRS1983

Short Shot Tower for Silicon

Drop length necessary to convert molten silicon to shot reduced by proposed new process. Conversion of silicon from powder or chunks to shot often simplifies processing. Shot is more easily handled in most processing equipment. Drops of liquid silicon fall through protective cloud of argon, then through rapidly cooling bath of methanol, where they quickly turn into solid shot.

Bates, H. E.↗
NASA NTRS1982

Mars - The regolith-atmosphere-cap system and climate change

A model is derived for the prediction of the Martian regolith-atmosphere-cap CO2 regime's behavior, as well as for the description of the roly of the regime in climate change, through descriptions of the time-temperature histories of 90 regolith 'chunks' on a latitude-depth grid. The influence of differences in regolith adsorption laws for basalt and clay, and the influence of variations in regolith depth with (1) latitude, (2) regolith thermal diffusivity, and (3) total exchangeable CO2 inventory on predicted variations in atmospheric pressure and cap mass, are examined. It is found that the atmosphere acts as a low capacity conduit between two reservoirs through which 10-100 times the current atmospheric mass of CO2 flows. The exchange between the reservoirs is driven by obliquity variations, with the polar cap the dominant CO2 sink at low obliquity and the regolith dominating at high obliquity.

Fanale, F. P.↗
NASA NTRS1984

Cold-Crucible Premelter for Silicon

System allows replenishment of silicon melt in crystal puller. Cold crucible consists of water-cooled, silver plated boat in 500kHz field. Induced secondary currents cause preheated chunks of silicon to melt. Magnetic repulsion between current in silicon and in boat prevents silicon from touching boat. Used for crystal growth of other materials sufficiently conductive and difficult to keep free of contamination by container walls at temmperature of operation.

Lane, R. L.↗
NASA NTRS1982

Advanced Czohcralski ingot growth

A summary of advanced Cz ingot-growth activities is presented. Five ingots (totalling 150 kg) were grown from one crucible by use of chunk silicon replenishment between ingot pulls. The cost of the ingot growth was reduced from $80/kg (conventional Cz growth) to $20/kg. Further improvements can be made by achieving a better understanding of crystalline silicon growth and the influence on growth of contaminants from the atmosphere and/or the crucible. This should lead to a higher percentage of monocrystalline growth and possible increased growth rates.

Lane, R. L.↗
NASA NTRS1984

Cometary nucleus and active regions

On the basis of the icy conglomerate model of cometary nuclei, various observations demonstrate the spotted nature of many or most nuclei, i.e., regions of unusual activity, either high or low. Rotation periods, spin axes and even precession of the axes are determined. The observational evidence for variations in activity over the surfaces of cometary nuclei are listed and discussed. On June 11 the comet IRAS-ARAKI-ALCOCK approached the Earth to a distance of 0.031 AU, the nearest since C/Lexell, 1770 I, providing a unique opportunity for near-nucleus observations. Preliminary analysis of these images establishes the spin axis of the nucleus, with an oblioquity to the orbit plane of approximately 50 deg, and a lag angle of sublimation approximately 35 deg from the solar meridian on the nucleus. Asymmetries of the inner coma suggests a crazy-quilt distribution of ices with differing volatility over the surface of the nucleus. The observations of Comet P/Homes 1892 III, exhibiting two 8-10 magnitude bursts, are carefully analyzed. The grazing encounter produced, besides the first great burst, an active area on the nucleus, which was rotating retrograde with a period of 16.3hr and inclination nearly 180 deg. After the first burst the total magnitude fell less than two magnitudes from November 7 to November 30 (barely naked eye) while the nuclear region remained diffuse or complex, rarely if ever showing a stellar appearance. The fading was much more rapid after the second burst. The grazing encounter distributed a volume of large chunks in the neighborhood of the nucleus, maintaining activity for weeks.

Whipple, F. L.↗