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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 235 records · Page 13
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Biomass burning aerosol radiative effects in the Southeast Atlantic depend strongly on meteorological forcing method

Biomass burning aerosols (BBAs) from African fires may strongly impact Earth’s radiation budget in the southeast Atlantic (SEA), but the sign and magnitude of the overall radiative effect (RE) remain uncertain. Aerosol–climate models are needed to separately quantify direct, indirect, and semi-direct REs. Here, we evaluate improved simulations with the UK Met Office's Unified Model and explore REs resulting from various methods used to match observed meteorology (nudging or running forecasts reinitialized at different frequencies). REs are calculated as differences in radiative fluxes between simulations with and without smoke emissions and with and without aerosol absorption. All model setups agree on net warming for the SEA dominated by the direct effect. Simulated smoke, clouds, and the direct effect agree better with observations than previous studies using the same model, though biases in aerosol extinction and liquid water path remain. Changes in cloud droplet number concentration due to BBA self-lofting influence how cleanly we can separate cloud effects into semi-direct and indirect effects. Total RE, which remains unaffected, ranges from +3.0 to +7.9 W m −2 . The 4.9 W m −2 spread arises mainly from simulated semi-direct effects. Forecasts three days long or less probably do not allow time for plausible differences in boundary layer properties due to semi-direct effects to accumulate. Free running simulations with and without smoke accumulate differences in meteorology that are likely spurious “butterfly effects”. We recommend future research quantifying BBA REs over weeks to months to use meteorological forcing techniques that allow aerosol absorption to affect the boundary layer.

Giuffrida, Eric [Carnegie Mellon University, Pitts↗
DOE OSTI2025

Impact of host climate model on contrail cirrus effective radiative forcing estimates

Estimates of aviation effective radiative forcing (ERF) indicate that contrail cirrus is currently its largest contributor, although with a substantial associated uncertainty of ∼ 70 %. Here, we implement the contrail parameterisation developed for the Community Atmosphere Model (CAM) in the UK Met Office Unified Model (UM), allowing us to compare, for the first time, the impact of key features of the host climate model on contrail cirrus ERF. We find that differences in background humidity between the models result in the UM-simulated contrail fractions being 2 to 3 times larger than in CAM. Additionally, the models show contrasting responses in overall global cloud fraction, with contrails increasing the total cloud fraction in the UM and decreasing it in CAM. Differences in the complexity of the cloud microphysics schemes lead to significant differences in simulated changes to cloud ice water content due to aviation. After compensating for the unrealistically low contrail optical depth in the UM, we estimate the 2018 contrail cirrus ERF to be 40.8 mW m−2 in the UM, compared to 60.1 mW m−2 in CAM. These values highlight the substantial uncertainty in contrail cirrus ERF due to differences in microphysics and radiation schemes between the two models. We also find a factor-of-8 uncertainty in contrail cirrus ERF due to existing uncertainty in contrail cirrus optical depth. Future research should focus on better representing microphysical and radiative contrail characteristics in climate models and on improved observational constraints.

Zhang, Weiyu [University of Leeds (United Kingdom)↗
DOE OSTI2024

code for "Improving the QBO forcing by resolved waves with vertical grid refinement in E3SMv2"

This is all code that used in the journal article "Improving the QBO forcing by resolved waves with vertical grid refinement in E3SMv2", including: Running and post processing E3SM: Run E3SM: run_E3SM.2023.scidac.MMF.amip.py Regrid: regrid.E3SM.py post processing, diagnostics, archive: run_post.2023.scidac.MMF.py TEM calculation, including filter TEM, E3SM: calculate.TEM.v2.py calculate.TEM.monthly_mean.v1.py TEM, ERA5: ERA5_calculate_TEM_90.py merge TEM data: merge_TEM_E3SM_ERA5.py TEM, filter, E3SM: filter_TEM_E3SM.py TEM, filter, ERA5: filter_TEM_ERA5.py WK wave analysis code from (https://github.com/brianpm/wavenumber_frequency): wavenumber_frequency_functions.py calculate the wave spectra so easy to plot: wk_calculation.py Make figures some functions for plot: plot.py code for drawing paper plots: figures_for_paper.ipynb

Hannah, WalterM↗
DOE OSTI2024

Using Multi-shaker Force Control Methods in Modal Analysis

Shaker excitation is a popular technique in experimental modal analysis because it gives the practitioner a high level of control and repeatability in the excitation. However, the dynamics of the shaker and test article can fundamentally limit the excitation bandwidth when a voltage-mode amplifier is used to power the shaker. Further, multiple shakers can couple to one-another through the test article and correlate the forces during a multiple-input / multiple-output modal test, potentially impa

Carter, Steven Phillip↗
DOE OSTI2024

Impact of tensor forces on quasifission product yield distributions

Quantum shell effects are crucial for the stability and structure of atomic nuclei and play a key role in the discovery of superheavy elements. Furthermore, during nuclear collisions, the dynamical evolution of these shell effects disrupts the equilibration process necessary for forming a compound nucleus, leading to the breakup of the initial composite as a result of quasifission. As such, quasifission reactions hinder the formation of a superheavy element.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2025

Self‐Healable Poly(ionic liquid) Copolymers Driven by Polar and Dipolar Forces

Abstract Commodity aliphatic and aromatic acrylic‐based copolymers self‐heal due to ubiquitouskey‐and‐lock,ring‐and‐lock, andfluorophilic‐σ‐lockvan der Waals (vdW) interactions. However, the role of these interactions in the presence of covalently copolymerized ionic liquid (IL) is not known. This study is driven by the hypothesis that covalently incorporated cation–anion pairs to form poly(ionic liquid) copolymers (PILCs) can perturb inter‐ or intra‐chain vdW interactions reflected in mechanical and electrical responses. To test this hypothesis, we synthesized a series of PILCs comprising of pentafluorostyrene (PFS) and imidazolium‐based IL monomers with variable‐length aliphatic tails (methyl and butyl). Using a combination of 2D 1 H‐ 1 H and 19 F ‐ 19 F NOESY NMR and FTIR measurements supplemented by molecular dynamic (MD) simulations, these studies demonstrate that preferentially alternating/random PILCs topologies facilitate self‐healing. The introduction of cation–anion moieties modifies thefluorophilic‐σ‐lockinteractions and, along with longer aliphatic tails ─(CH 2 ) 3 CH 3 covalently attached to the imidazolium cation, enhances cation‐anion mobility, thus faster recovery from mechanical damage occurs. These findings underline how precise control over dipolar and ionic interactions through copolymer composition enables self‐healing in PILCs. These insights may open pathways for designing sustainable, mechanically resilient materials for applications in energy storage and energy harvesting.

Chemistry↗
DOE OSTI2026

Constraints on long-range forces in de Sitter space

The representation theory of de Sitter space admits partially massless (PM) particles, but whether such particles can participate in consistent interacting theories remains unclear. We investigate the consistency of theories containing PM fields, particularly when these fields are coupled to gravity. Our strategy exploits the fact that PM fields correspond to partially conserved currents on the spacetime boundary, which generate symmetries. These symmetries place stringent constraints on correlation functions of charged operators, allowing us to test the consistency of a proposed bulk spectrum. When the assumed operator content violates these constraints, the corresponding bulk theory is ruled out. Applying this framework, we show that, in four-dimensional de Sitter space, PM fields of spin 2 or 3 (at depth 0) cannot couple consistently to gravity: such couplings necessitate additional massive fields, which are inevitably non-unitary. In higher dimensions, however, the constraints can be satisfied without violating unitarity if further PM fields are included. The resulting structure leads to additional charge conservation laws, which suggests that consistency may ultimately require an infinite tower of higher-spin PM fields, akin to the situation for ordinary higher-spin symmetries. The methods developed here provide powerful constraints on possible long-range interactions in de Sitter space and delineate the landscape of consistent quantum field theories in cosmological spacetimes.

AdS-CFT Correspondence↗
DOE OSTI2025

Clarity through the neutrino fog: constraining new forces in dark matter detectors

The PandaX-4T and XENONnT experiments present indications of Coherent Elastic Neutrino Nucleus Scattering (CEνNS) from 8 B solar neutrinos at 2.6σ and 2.7σ, respectively. This constitutes the first observation of the neutrino “floor” or “fog”, an irreducible background that future dark matter searches in terrestrial detectors will have to contend with. Here, we first discuss the contributions from neutrino–electron scattering and from the Migdal effect in the region of interest of these experiments, and we argue that they are non-negligible. Second, we make use of the recent PandaX-4T and XENONnT data to derive novel constraints on light scalar and vector mediators coupling to neutrinos and quarks. We demonstrate that these experiments already provide world-leading laboratory constraints on new light mediators in some regions of parameter space.

neutrino interactions↗