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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 757 records · Page 42
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Galvanic corrosion of AZ31B joined to dual-phase steel with and without Zn layer by ultrasonic and friction stir welding

Galvanic corrosion of AZ31B joined with bare or Zn-coated DP590 steel by ultrasonic spot welding or linear friction stir welding was quantitatively studied by pre-defining anode and cathode in the lap joint samples. Corrosion volume and depth from Mg anode surfaces exposed to 0.1 M sodium chloride solution was analyzed as functions of cathode surface type and welding method. Characterization of as-welded joints was performed to identify any microstructural feature of the bonding zone that could impact galvanic corrosion behavior. COMSOL modeling with modified user subroutine was conducted to simulate the progression of Mg corrosion in the same joint and electrode configurations used for the corrosion experiments. The experimental results indicated that Zn-coated cathode surface can reduce Mg galvanic corrosion significantly as galvanic polarization and cathodic current on Zn-coated surface remained relatively low for Mg in the weld joints. COMSOL modeling described the growth of Mg galvanic corrosion in a reasonable manner but showed limitation by underestimating the corrosion volume as it did not capture self-corrosion.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Characterization of high thermal conductivity fuel surrogates before and after ion irradiation

High thermal conductivity nuclear fuels offer important potential advantages over traditional oxide-based fuels such as higher burnup, reduction in fission gas release, and better overall safety of the system. One proposed approach to high thermal conductivity fuels utilizes high thermal conductivity nonfissile additives with UO 2 fuel to lower the fuel operating temperature and thereby take advantage of the highly favorable radiation resistance of UO 2 at lower operating temperatures. However, differential swelling in the matrix and high conductivity additive phases during high dose irradiation could lead to internal cracking and poor performance. In the current study, ceria (CeO 2 ) and zirconia (ZrO 2 ) surrogate matrices were used to model UO2 behavior. Additives of 10 vol. % Al 2 O 3 or SiC in the form of short fibers or platelets were used for the high conductivity second phase. The nuclear fuel surrogates were sintered to achieve densities greater than 93% of the ideal values. Scanning electron microscopy (SEM) imaging and X-ray diffraction confirmed the uniform distribution of the second phase and that no intermetallic second phase was formed during sintering. The thermal conductivity of the sintered samples was measured from 50 °C to 900 °C and confirmed the desirable increase compared to pure CeO 2 /ZrO 2 pellets. Samples were irradiated with 20 MeV Ni 6+ ions at midrange doses ranging from 1 to 15 displacements per atom (dpa) and temperatures from 300 °C to 700 °C. Post irradiation characterization revealed a good stability of the samples at low to medium doses with matrix lattice parameter swelling of < 0.14 % but showed a significant microstructural deterioration and decrease of the mechanical properties at 15 dpa.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2020

Formation of helices with controllable chirality in gel-fiber composites

While microscale helices with specified chirality are pervasive in biological systems, driving purely synthetic materials to self-organize into such useful structures remains a significant challenge. Through theory and simulations, we model the behavior of initially flat ribbons of gel-fiber composites and show that these materials self-organize into three-dimensional helices with the application of heat. We specifically focus on thermo-responsive gels, which shrink when heated to a point near the lower critical solubility temperature (LCST). Within the composite, regions of the LCST gel that lie far from the fibers can readily shrink in response to the increased temperature; however, near the fibers the network is inhibited from undergoing the heat-induced collapse. This competition between the constrained and the unconstrained regions of the heated sample plays a vital role in the structural evolution of the material. Additionally, we find that this dynamic process can be controlled through the careful placement of the fibers on the outer surface of the gel. We specifically identify fiber arrangements that lead to the formation of helical structures with controlled chirality. Moreover, we isolate scenarios where constraining the movement of one or both the free ends of the sample promotes and stabilizes the formation of helical structures with specified handedness. Such structurally tailored composites are useful for creating mechanically robust actuators, and “appendages” for soft robots that can controllably curl and uncurl with variations in temperature.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Gas Evolution in Water Electrolysis

Gas bubbles generated by the hydrogen evolution reaction and oxygen evolution reaction during water electrolysis influence the energy conversion efficiency of hydrogen production. Here we survey what is known about the interaction of gas bubbles and electrode surfaces and the influence of gas evolution on practicable devices used for water electrolysis. Here, we survey the physical processes occurring during the life cycle of a bubble, summarize techniques used to characterize gas evolution phenomena in-situ and in practical device environments, and discuss ways that electrodes can be tailored to facilitate gas removal at high current densities. Lastly, we summarize efforts to model the behavior of individual gas bubbles and multiphase flows produced at gas evolving electrodes. We conclude our review with a short summary of outstanding questions which could be answered by future efforts to characterize gas evolution in electrochemical device environments or by improved simulations of multiphase flows.

Bubbles↗
DOE OSTI2023

Unexpected Kinetic Solvent Effects Enhance Activity and Selectivity in Biphasic Systems

Biphasic dehydration of fructose to 5-hydroxymethylfurfural (HMF) has shown unprecedented increases in productivity, but a mechanistic understanding is lacking. Herein, we couple fast experimental reaction kinetics, multiscale modeling (phase behavior, classical molecular dynamics(MD), and quantum mechanics/molecular mechanics MD), in situ sampling, and IR and 13 C-NMR spectroscopy to elucidate the complex effects of nonpolar extracting organic solvents on the kinetics of fructose dehydration. We show that these organic solvents can reach significant mutual solubility with water at reaction temperatures, enabling the partition of the sugar and catalyst into the extracting phase. In the organic-rich environment, the dehydration of fructose proceeds faster and more selectively than in water due to increased relative abundance of the reactive furanose isomer, enhanced water–catalyst–substrate interactions driven by nanophase separation, and higher product stability stemming from preferential solvation. Furthermore, we demonstrate that these solvent effects impact other critical biphasic reactions in biomass upgrading and provide qualitative principles for solvent selection.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2026

Observations of Offshore Low‐Level Jets Off the U.S. East Coast Reveal Systematic Biases in ERA5 and HRRR

Low-level jets (LLJs)—wind speed maxima typically occurring a few hundred meters above the surface—are common off the U.S. East Coast and influence many atmospheric processes with societal importance, including cloud formation, aviation safety, and search-and-rescue. However, their vertical structure and frequency remain poorly quantified due to limited offshore observations. This study presents new scanning Doppler LiDAR and infrared spectroradiometer data from the 2024 summer deployment of an offshore barge during the Wind Forecast Improvement Project 3. These coupled wind and temperature profiles provide unprecedented resolution to assess LLJ behavior and model performance. LLJs occurred in over 21% of observed profiles, with a weak diurnal preference for nighttime and early morning hours and maximum winds typically near 300 m. Both ERA5 and High-Resolution Rapid Refresh analysis underestimate jet wind speeds and misrepresent the boundary layer thermal structure. These results highlight persistent model biases and the critical need for high-resolution offshore observations.

17 WIND ENERGY↗
DOE OSTI2022

Platinum nanoparticle compression: Combining in situ TEM and atomistic modeling

The mechanical behavior of nanoparticles governs their performance and stability in many applications. However, the small sizes of technologically relevant nanoparticles, with diameters in the range of 10 nm or less, significantly complicate experimental examination. These small nanoparticles are difficult to manipulate onto commercial test platforms and deform at loads that are below the typical noise floor of the testing instruments. Here, we synthesized small platinum nanoparticles directly onto a mechanical tester and used a modified nanomanipulator to enhance load resolution to the nanonewton scale. We demonstrated the in situ compression of an 11.5-nm platinum nanoparticle with simultaneous high-resolution measurements of load and particle morphology. Molecular dynamics simulations were performed on similarly sized particles to achieve complementary measurements of load and morphology, along with atomic resolution of dislocations. The experimental and simulation results revealed comparable values for the critical resolved shear stress for failure, 1.28 and 1.15 GPa, respectively. Altogether, this investigation demonstrated the promise of, and some initial results from, the combination of atomistic simulations and in situ experiments with an unprecedented combination of high spatial resolution and high load resolution to understand the behavior of metal nanoparticles under compression.

42 ENGINEERING↗
DOE OSTI2024

A Gaussian process guide for signal regression in magnetic fusion

Extracting reliable information from diagnostic data in tokamaks is critical for understanding, analyzing, and controlling the behavior of fusion plasmas and validating models describing that behavior. Recent interest within the fusion community has focused on the use of principled statistical methods, such as Gaussian process regression (GPR), to attempt to develop sharper, more reliable, and more rigorous tools for examining the complex observed behavior in these systems. While GPR is an enormously powerful tool, there is also the danger of drawing fragile, or inconsistent conclusions from naive GPR fits that are not driven by principled treatments. Here we review the fundamental concepts underlying GPR in a way that may be useful for broad-ranging applications in fusion science. We also revisit how GPR is developed for profile fitting in tokamaks. We examine various extensions and targeted modifications applicable to experimental observations in the edge of the DIII-D tokamak. Finally, we discuss best practices for applying GPR to fusion data.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2024

Seeking help for perinatal depression and anxiety: a systematic review of systematic reviews from an interdependent perspective

Abstract Background Seeking help for perinatal mood and anxiety disorders is crucial for women’s mental health and babies’ development, yet many women do not seek help for their condition and remain undiagnosed and untreated. This systematic review of systematic reviews aimed at summarizing and synthesizing findings from all systematic reviews on seeking help for PMAD in the context of interdependence theory, highlighting the interdependent relationship between women and healthcare providers and how it may impact women’s seeking-help process. Methods Four electronic databases were searched, and 18 studies published up to 2023 met inclusion criteria for review. Results The capability, opportunity and motivation model of behavior was used as a framework for organizing and presenting the results. Results demonstrate that seeking help for PMAD is a function of the interdependent relationship between perinatal women’s and healthcare providers’ psychological and physical capabilities, social and physical opportunities, and their reflective and automatic motivation. Conclusions Unmet needs in perinatal mental healthcare is an important public health problem. This systematic review of systematic reviews highlights key factors for policymakers, researchers, and practitioners to consider to optimize healthcare systems and interventions in a way that enhances perinatal women’s treatment whenever necessary.

Bina, Rena (ORCID:0000000340729229)↗
DOE OSTI2026

Imaging systematics induced by galaxy subsample fluctuation: New systematics at second order

Imaging systematics refers to the inhomogeneous distribution of a galaxy sample caused by varying observing conditions and astrophysical foregrounds. Current mitigation methods correct the galaxy density fluctuations $n$ gal /$\bar{n}$ gal caused by imaging systematics assuming that all galaxies in a sample have the same $n$ gal /$\bar{n}$ gal . Under this assumption, the corrected sample cannot perfectly recover the true correlation function. Here, we name this effect subsample systematics. For a galaxy sample, even if its overall sample statistics [redshift distribution 𝑛⁡(𝑧), galaxy bias 𝑏⁡(𝑧)], are accurately measured, 𝑛⁡(𝑧), 𝑏⁡(𝑧) can still vary across the observed footprint. It makes the correlation function amplitude of galaxy clustering higher, while correlation functions for galaxy-galaxy lensing and cosmic shear do not have noticeable change. Such a combination could potentially degenerate with physical signals on small angular scales, such as the amplitude of galaxy clustering, the impact of neutrino mass on the matter power spectrum, etc. subsample systematics cannot be corrected using imaging systematics mitigation approaches that rely on the cross-correlation signal between imaging systematics maps and the observed galaxy density field. In this paper, we derive formulated expressions of subsample systematics, demonstrating its fundamental difference with other imaging systematics. We also provide several toy models to visualize this effect. Finally, we discuss a potential method to estimate and mitigate subsample systematics by forward modeling its behavior using synthetic source injection.

Kong, Hui [The Barcelona Institute of Science and ↗
DOE OSTI2026

Flux trapping in NbTiN strips

We use scanning superconducting quantum interference device (SQUID) microscopy to image vortices in superconducting structures fabricated from NbTiN thin films. We repeatedly cool superconducting strips with different width in an applied magnetic field and image the individual vortices. From these images we determine the threshold field at which the first vortex enters a strip and the number and configuration of vortices beyond this threshold field. We model the behavior of the vortices with and without considering the effect of pinning using numerical methods to minimize the Gibbs free energy of vortices in the strips. Our measurements provide a first benchmark to investigate the flux trapping properties of NbTiN thin films directly relevant to NbTiN-based superconducting digital circuits.

Bai, Ruiheng [Cornell University] (ORCID:000000025↗
DOE OSTI2025

Thermal energy transport in laser-driven high x-ray conversion efficiency metallic silver nanowire foams

Here, we report on record brightness from Ag x-ray emission obtained using a novel laser-produced plasma source. The reported K-shell conversion efficiency of nearly 1% with a radiant energy of ≈ 0.6 kJ/sr from Ag ions is the highest presently recorded and is about twofold greater than more conventional metal-lined cavity targets. He-like Ag ions are the dominant radiators at ≈ 22.7 keV, which contrast the x-ray sources from other pulse power facilities that produce K-shell x-rays from Auger processes in near-neutral ions driven by the nonthermal hot electrons produced in the Z-pinch implosion. The reported x-ray emission was produced from a 4-mm-diameter, 4-mm-long underdense silver nanowire target at 10⁢ mg/⁢cm 3 . The National Ignition Facility laser beams deposited ≈ 1000 kJ of 3ω light into the target with a ≈ 400 TW, 2.5 ns square pulse. Finally, we show via comparisons of data with radiation-hydrodynamics simulations that flux-limited classical thermal energy transport models are inadequate in correctly modeling the behavior of these non-local thermodynamic equilibrium plasmas.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2021

Iridium valence variation and carrier sign tuning in ( Ca , Ba ) x La 2 – x CuIrO 6 double perovskites

Here, we report the structure and properties of ( Ca , Ba ) x La 2 – x CuIrO 6 . The rock-salt double perovskite structure goes through a P 1 ¯ to P 2 1 / n phase transition with increasing Ba content but not with Ca content. In both cases, the Ir ion is oxidized from 4 + to 5 + with increasing substitution. Transport and magnetic properties measurements reveal that all compositions are insulating with hysteretic spin-freezing magnetic behavior. Seebeck coefficient measurements reveal a large thermopower change from + 176 μ V /K in La 2 CuIrO 6 to – 223 μ V /K with increasing Ba content in Ba x La 2 – x CuIrO 6 . This behavior is modeled well by the Heikes formula for correlated hopping conduction. ( Ca , Ba ) x La 2 – x CuIrO 6 provides a model system for investigations of other systems with similar carrier sign tuning, with applications toward semiconductors and thermoelectric materials.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Structural and electronic changes in L⁢i 2 ⁢Ru⁢O 3 induced by lithium intercalation

Despite extensive research on oxide battery cathodes that transcend classical cationic redox activity, the detailed interplay between structural transformations and electronic redox processes remains insufficiently understood. We report a detailed study of the sequential structural and electronic changes in Li 2 RuO 3 upon lithium intercalation, characterized by powder x-ray and neutron diffraction alongside Ru and O K-edge x-ray absorption spectroscopy (XAS), and guided by operando synchrotron x-ray diffraction. During delithiation, Li 2 RuO 3 evolves from a well-defined monoclinic state to a complex trigonal phase via multiple intermediate structures, marked by significant changes in Ru-O bond distances that closely track the transition from a classical cationic redox to an unconventional process centered at oxygen states. Armed with high-quality atomic structural descriptions, computational models of the O K-edge XAS closely reproduce the experimentally observed spectral shifts. Lastly, we relate observations of electrochemical hysteresis with concurrent changes in the pathways of structural and electronic transitions. In conclusion, our results not only clarify the mechanisms underpinning voltage hysteresis in a model for lattice oxygen redox but also underscore the importance of structural fidelity in modeling redox behavior when this type of complex reactivity is present.

Li, Haifeng [Univ. of Illinois, Chicago, IL (Unite↗
DOE OSTI2023

TOWARDS RAPID RESPONSE UPDATES OF POPULATIONS AT RISK

Understanding population at risks has been a focus of the LandScan program through its development of population estimates. With advancements in computer vision, deep learning technologies and access to High Performance Computing (HPC) and high resolution imagery, population estimates are now modeled at the building level. However, when those patterns are disrupted, rapid updates to population distribution estimates are needed to support humanitarian aid and response. Oak Ridge National Laboratory (ORNL) recently adapted an existing deep learning building footprint extraction model in development of a scalable approach to Building Damage Assessments (BDA). This new opportunity opens the possibility of automating BDA to support rapid population distribution estimate updates for geographic areas involved in geopolitical conflicts or natural events for humanitarian aid and response or where to focus recovery efforts. In addition, incorporate social surveys to further model human behavior under conflict or other scenarios that disrupt normal patterns of life.

Urban, Marie↗
DOE OSTI2023

Developing a Disaster-Ready Power Grid Agent Through Geophysically-Informed Fault Event Scenarios

Management of the nation’s power grid over the coming decades will need to factor multiple climate-driven threats to the power system that can be stressful or even detrimental to its operations. During disasters, grid operators suffer from cognitive overload where the electric grid is severely impacted by the weather, yet grid operators have limited awareness of these factors. Meanwhile, the electric grid is facing an explosion of data coming from a variety of sources which can enable the operator to evaluate the risks and develop mitigation strategies against hazardous events. In this work, we processed heterogeneous environmental and power grid data to learn and model grid behavior caused by extreme weather events. In this study, we focused on two weather-driven hazards, hurricanes and wildfires, which were analysed for the electric grid of Texas. We the used this data to train a Reinforcement Learning (RL) agent by analysing and predicting future behaviour of the grid during those hazard events. All these parts are incorporated in one framework to have a geophysically informed power simulators that can be used to train RL agents.

electic grid, reinforcement learning, climate adap↗
DOE OSTI2025

Incorporating Elevation in Traffic-Vehicle CO-Simulation: Issues, Impacts, and Solutions

Traffic-vehicle co-simulation couples microscopic traffic simulation with full-body vehicle dynamics to assess system-level impacts on mobility, energy, and safety with greater realism. Incorporating elevation is critical for accurately modeling vehicle behavior and energy use, especially for gradient-sensitive vehicles such as electric and heavy-duty trucks. However, raw elevation data often contain noise, discontinuities, and inconsistencies. While such issues may be negligible in traditional traffic simulations, they significantly affect traffic-vehicle co-simulations where vehicle dynamics are sensitive to road grade variations. This paper investigates the impact of unprocessed elevation data on vehicle behavior and energy consumption using a 42-mile simulation along Interstate 81. We propose an elevation processing workflow that can mitigate the effects stem from elevation data issues, improving the realism and stability of traffic-vehicle co-simulation. Results show that the method effectively removes noise and abrupt elevation transitions while preserving roadway geometry.

Xu, Guanhao [ORNL] (ORCID:0000000214326357)↗
DOE OSTI2025

Microbead Encapsulation for Protection of Electronic Components

Here, this study investigates the application of microbeads as an innovative encapsulation technique to protect electronic components from harsh mechanical strain. Traditional encapsulation methods using hard epoxy provide substantial mechanical support but create thermal expansion mismatch issues, potentially leading to electronic component failure. We explore the use of finely powdered microbeads to achieve protective structures combining stiffness and energy absorption. The research focuses on key variables, including microbead size, microbead roughness, compaction of microbeads, and circuit board mounting in the encapsulation, all of which influence the encapsulation’s effectiveness. Experimental setups and testing protocols were developed to assess the performance of various microbead materials under different impact conditions. Results demonstrate that microbead encapsulation significantly reduces strain on circuit boards, minimizing the risk of damage during mechanical shocks. However, challenges remain, such as optimizing microbead characteristics and modeling their behavior within large-scale circuit board assemblies. Despite these challenges, the findings suggest that microbead encapsulation offers a promising alternative to conventional methods, enhancing the durability and reliability of electronic components in high-stress environments.

42 ENGINEERING↗