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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 OSTI2023

Time-dependent density-functional-theory calculations of the nonlocal electron stopping range for inertial confinement fusion applications

Nonlocal electron transport is important for understanding laser-target coupling for laser-direct-drive (LDD) inertial confinement fusion (ICF) simulations. Current models for the nonlocal electron mean free path in radiation-hydrodynamic codes are based on plasma-physics models developed decades ago; improvements are needed to accurately predict the electron conduction in LDD simulations of ICF target implosions. Here we utilized time-dependent density functional theory (TD-DFT) to calculate the electron stopping power (SP) in the so-called conduction-zone plasmas of polystyrene in a wide range of densities and temperatures relevant to LDD. Compared with the modified Lee-More model, the TD-DFT calculations indicated a lower SP and a higher stopping range for nonlocal electrons. We fit these electron SP calculations to obtain a global analytical model for the electron stopping range as a function of plasma conditions and the nonlocal electron kinetic energy. This model was implemented in the one-dimensional radiation-hydrodynamic code LILAC to perform simulations of LDD ICF implosions, which are further compared with simulations by the standard modified Lee-More model. In conclusion, results from these integrated simulations are discussed in terms of the implications of this TD-DFT-based mean-free-path model to ICF simulations.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2021

Phonon-Mediated Long-Range Attractive Interaction in One-Dimensional Cuprates

Establishing a minimal microscopic model for cuprates is a key step towards the elucidation of a high-T c mechanism. By a quantitative comparison with a recent in situ angle-resolved photoemission spectroscopy measurement in doped 1D cuprate chains, our simulation identifies a crucial contribution from long-range electron-phonon coupling beyond standard Hubbard models. Using reasonable ranges of coupling strengths and phonon energies, we obtain a strong attractive interaction between neighboring electrons, whose strength is comparable to experimental observations. Additionally, nonlocal couplings play a significant role in the mediation of neighboring interactions. Considering the structural and chemical similarity between 1D and 2D cuprate materials, this minimal model with long-range electron-phonon coupling will provide important new insights on cuprate high-T c superconductivity and related quantum phases.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2024

Emergence of Long-Range Angular Correlations in Low-Multiplicity Proton-Proton Collisions

This Letter presents the measurement of near-side associated per-trigger yields, denoted ridge yields, from the analysis of angular correlations of charged hadrons in proton-proton collisions at s = 13 TeV . Long-range ridge yields are extracted for pairs of charged particles with a pseudorapidity difference of 1.4 < | Δ η | < 1.8 and a transverse momentum of 1 < p T < 2 GeV / c , as a function of the charged-particle multiplicity measured at midrapidity. This Letter extends the measurements of the ridge yield to the low multiplicity region, where in hadronic collisions it is typically conjectured that a strongly interacting medium is unlikely to be formed. The precision of the new low multiplicity results allows for the first direct quantitative comparison with the results obtained in e + e − collisions at s = 91 GeV and s = 183 – 209 GeV , where initial-state effects such as preequilibrium dynamics and collision geometry are not expected to play a role. In the multiplicity range 8 ≲ ⟨ N ch ⟩ ≲ 24 where the e + e − results have good precision, the measured ridge yields in p p collisions are substantially larger than the limits set in e + e − annihilations. Consequently, the findings presented in this Letter suggest that the processes involved in e + e − annihilations do not contribute significantly to the emergence of long-range correlations in p p collisions. © 2024 CERN, for the ALICE Collaboration 2024 CERN

43 PARTICLE ACCELERATORS↗
DOE OSTI2021

Thermomagnetic properties of Bi 2 Te 3 single crystal in the temperature range from 55 K to 380 K

Magnetothermoelectric transport provides an understanding of coupled electron-hole-phonon current in topological materials and has applications in energy conversion and cooling. In this paper, we study the Nernst coefficient, the magneto-Seebeck coefficient, and the magnetoresistance of single-crystalline Bi 2 Te 3 under external magnetic field in the range of –3T to 3T and in the temperature range of 55 K to 380 K. Moreau's relation is employed to justify both the overall trend of the Nernst coefficient and the temperature at which this coefficient changes sign. We observe a nonlinear relationship between the Nernst coefficient and the applied magnetic field in the temperature range of 55 K to 255 K. An increase in both the Nernst coefficient and the magneto-Seebeck coefficient is observed as the temperature is reduced which can be attributed to the increased mobility of the carriers at lower temperatures. First-principles density functional theory calculations were carried out to physically model the experimental data including electronic and transport properties. Simulation findings agreed with the experiments and provide a theoretical insight to justify the measurements.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Extending synchrotron SAXS instrument ranges through addition of a portable, inexpensive USAXS module with vertical rotation axes

Ultra-SAXS can enhance the capabilities of existing synchrotron SAXS/WAXS beamlines. A compact ultra-SAXS module has been developed, which extends the measurable q -range with 0.0015 ≤ q (nm −1 ) ≤ 0.2, allowing structural dimensions in the range 30 ≤ D (nm) ≤ 4000 to be probed in addition to the range covered by a high-end SAXS/WAXS instrument. By shifting the module components in and out on their respective motor stages, SAXS/WAXS measurements can be easily and rapidly interleaved with USAXS measurements. The use of vertical crystal rotation axes (horizontal diffraction) greatly simplifies the construction, at minimal cost to efficiency. In this paper, the design considerations, realization and synchrotron findings are presented. Measurements of silica spheres, an alumina membrane, and a porous carbon catalyst are provided as application examples.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2024

Long-Range Biometric Identification in Real World Scenarios: A Comprehensive Evaluation Framework Based on Missions

The considerable body of data available for evaluating biometric recognition systems in Research and Development (R&D) environments has contributed to the increasingly common problem of target performance mismatch. Biometric algorithms are frequently tested against data that may not reflect the real world applications they target. From a Testing and Evaluation (T&E) standpoint, this domain mismatch causes difficulty assessing when improvements in State-of-the-Art (SOTA) research actually translate to improved applied outcomes. This problem can be addressed with thoughtful preparation of data and experimental methods to reflect specific use-cases and scenarios.To that end, this paper evaluates research solutions for identifying individuals at ranges and altitudes, which could support various application areas such as counterterrorism, protection of critical infrastructure facilities, military force protection, and border security. We address challenges including image quality issues and reliance on face recognition as the sole biometric modality. By fusing face and body features, we propose developing robust biometric systems for effective long-range identification from both the ground and steep pitch angles. Preliminary results show promising progress in whole-body recognition. This paper presents these early findings and discusses potential future directions for advancing long-range biometric identification systems based on mission-driven metrics.

Aykac, Deniz↗
DOE OSTI2023

Increased range and contrast in fog with circularly polarized imaging

Fogs, low lying clouds, and other highly scattering environments pose a challenge for many commercial and national security sensing systems. Current autonomous systems rely on optical sensors for navigation whose performance is degraded by highly scattering environments. In our previous simulation work, we have shown that polarized light can penetrate through a scattering environment such as fog. We have demonstrated that circularly polarized light maintains its initial polarization state better than linearly polarized light, even through large numbers of scattering events and thus ranges. This has recently been experimentally verified by other researchers. In this work, we present the design, construction, and testing of active polarization imagers at short-wave infrared and visible wavelengths. We explore multiple polarimetric configurations for the imagers, focusing on linear and circular polarization states. The polarized imagers were tested at the Sandia National Laboratories Fog Chamber under realistic fog conditions. Here, we show that active circular polarization imagers can increase range and contrast in fog better than linear polarization imagers. We show that when imaging typical road sign and safety retro-reflective films, circularly polarized imaging has enhanced contrast throughout most fog densities/ranges compared to linearly polarized imaging and can penetrate over 15 to 25 m into the fog beyond the range limit of linearly polarized imaging, with a strong dependence on the interaction of the polarization state with the target materials.

47 OTHER INSTRUMENTATION↗
DOE OSTI2025

Eureka: Enabling Fine-Grained Access and Range Queries on Compressed Scientific Data via Data-Index Co-Compression

Handling large-scale scientific data in high-performance computing (HPC) environments poses significant challenges, including excessive I/O, high storage costs, and slow query performance. Traditional approaches often require full data decompression and scans, making them impractical for real-time or interactive analysis. To address these limitations, we introduce Eureka, a unified data-index co-compression framework that enables fine-grained access and efficient range queries on compressed scientific datasets. Eureka integrates spatial domain decomposition with block-wise error-bounded lossy compression to support selective decompression. It constructs a hierarchical AVL-tree index during compression to capture block-level value ranges, enabling fast pruning during query execution. To reduce metadata overhead, the index itself is also compressed while ensuring recall-preserving results. Experiments on six diverse HPC simulation datasets show that Eureka achieves up to 25x data compression and over 300x index compression, surpassing state-of-the-art compressors such as SZ3 and ZFP in rate-distortion performance. Additionally, Eureka delivers over 30x speedup for low-selectivity range queries, making it a scalable and efficient solution for modern scientific data analysis.

Yan, Ning↗
DOE OSTI2019

AmeriFlux US-xSR NEON Santa Rita Experimental Range (SRER)

This is the AmeriFlux version of the carbon flux data for the site US-xSR NEON Santa Rita Experimental Range (SRER). Site Description - Santa Rita Experimental Range encompasses 21,000 hectares of upland Sonoran Desert, approximately 32 km south of Tucson, Arizona. Santa Rita Experimental Range was founded in 1903. It is the longest continuously active rangeland research facility and among the five oldest biological field stations in the United States. The site is broken into distinct pastures, through which cattle graze throughout the year in various densities and durations.

Network), NEON (National Ecological Observatory↗
DOE OSTI2021

AmeriFlux US-Jo1 Jornada Experimental Range Bajada Site

This is the AmeriFlux version of the carbon flux data for the site US-Jo1 Jornada Experimental Range Bajada Site. Site Description - The Jornada Basin Experimental Range (JER) covers 783 km2 in the La Jornada del Muerto Plain of the northern Chihuahuan Desert and is located 20km of Las Cruces, NM. Extensive livestock grazing at the JER and througout the US Southwest was coincident with large-scale grassland deterioration and transition to shrubland begining in the 1800s. The JER was established n 1912 to investigate these rangeland changes and has since become a central location for understanding dryland ecology. This flux tower monitors CO2 and H2O dynamics in a representative shrubland on the piedmont slope (bajada) of the San Andreas mountains. The dominant shrubs are evergreen Larrea tridentata (Creosote) and winter-deciduous Prosopis glandulosa (Honey Mesquite). Other cover types include Flourensia cernua (tarbush) and patchy occurences of the grasses Muhlenbergia porteri (Bush Muhly) and Dasyochloa pulchella (Fluff Grass). The site is occasionally visited by stray domestic cattle, free-ranging introduced Oryx, and other native herbivores (Jack Rabbits, Desert Pronghorn). Soils at the site are Ustic Calciargids and parent material consists of limestone, other sedimentary rock, and some igneous rock. Virtual Site Visit: https://youtu.be/v1uJCKuicqs​

Tweedie, Craig↗
DOE OSTI2022

AmeriFlux FLUXNET-1F US-Jo2 Jornada Experimental Range Mixed Shrubland

This is the AmeriFlux Management Project (AMP) created FLUXNET-1F version of the carbon flux data for the site US-Jo2 Jornada Experimental Range Mixed Shrubland. This is the FLUXNET version of the carbon flux data for the site US-Jo2 Jornada Experimental Range Mixed Shrubland produced by applying the standard ONEFlux (1F) software. Site Description - The study area is in a mixed shrub-dominated portion of the San Andres Mountain piedmont, along the southeastern boundary of the Jornada Experimental Range (JER) in southern New Mexico, USA. The JER was established in 1912 as a response of scientis and landowner to the shrub enchroachment and loss of grasses due to extended grazing during the late 1800s, fire and climate change. JER has been a NSF LTER site since 1981.The study site is a small watershed (4.67 ha) in an alluvial slope or bajada, with three major areas (north-, south- and west-facing hillslopes) with low to moderate slopes (∼0–6°) with a mean slope of 2.6°, while the channel banks and propagating channel heads have higher slopes (∼15–25°). The site is charactetized by a high bare soil coverage (∼66%), ∼28% of mixed shrubs coverage and a low coverage of grass (∼4%) and weeds (∼2%).

Vivoni, Enrique R.↗
DOE OSTI2023

AmeriFlux FLUXNET-1F US-xAE NEON Klemme Range Research Station (OAES)

This is the AmeriFlux Management Project (AMP) created FLUXNET-1F version of the carbon flux data for the site US-xAE NEON Klemme Range Research Station (OAES). This is the FLUXNET version of the carbon flux data for the site US-xAE NEON Klemme Range Research Station (OAES) produced by applying the standard ONEFlux (1F) software. Site Description - The 1,560-acre Klemme Range Research Station is a grassland site managed for livestock grazing and pasture, located in the middle of the Rolling Red Plains Resource Area. The Rolling Red Plains extends from south of the Red River to north of the Oklahoma/Kansas border consisting of approximately 9.4 million acres, which occupies a significant portion of Western Oklahoma excluding the Oklahoma Panhandle.

Network), NEON (National Ecological Observatory↗
DOE OSTI2023

AmeriFlux FLUXNET-1F US-xCP NEON Central Plains Experimental Range (CPER)

This is the AmeriFlux Management Project (AMP) created FLUXNET-1F version of the carbon flux data for the site US-xCP NEON Central Plains Experimental Range (CPER). This is the FLUXNET version of the carbon flux data for the site US-xCP NEON Central Plains Experimental Range (CPER) produced by applying the standard ONEFlux (1F) software. Site Description - Central Plains Experimental Range (CPER) site in north central Colorado. CPER served as part of the Shortgrass Steppe LTER from 1982-2014 and is now home to a fully instrumented NEON site and a wealth of relevant historical data as well as ongoing collections of complementary data(i.e. airborne remote sensing, soil temperature and moisture, phenology measurements, plant biomass and more)

Network), NEON (National Ecological Observatory↗
DOE OSTI2023

AmeriFlux FLUXNET-1F US-Rpf Poker Flat Research Range: Succession from fire scar to deciduous forest

This is the AmeriFlux Management Project (AMP) created FLUXNET-1F version of the carbon flux data for the site US-Rpf Poker Flat Research Range: Succession from fire scar to deciduous forest. This is the FLUXNET version of the carbon flux data for the site US-Rpf Poker Flat Research Range: Succession from fire scar to deciduous forest produced by applying the standard ONEFlux (1F) software. Site Description - This tower is located near Davis Center, Poker Flat Research Range. Deciduous trees and shrubs are dominated at the burned black spruce forest.

Ueyama, Masahito↗
DOE OSTI2023

AmeriFlux FLUXNET-1F US-xSJ NEON San Joaquin Experimental Range (SJER)

This is the AmeriFlux Management Project (AMP) created FLUXNET-1F version of the carbon flux data for the site US-xSJ NEON San Joaquin Experimental Range (SJER). This is the FLUXNET version of the carbon flux data for the site US-xSJ NEON San Joaquin Experimental Range (SJER) produced by applying the standard ONEFlux (1F) software. Site Description - Located at The San Joaquin Experimental Range, in the western foothills of the Sierra Nevada, this 18.2 kilometer terrestrial field site is a mix of open woodlands, shrubs and grasslands with low density cattle grazing. SJER is an ecosystem research experimental area. It was originally conceived as a cooperative interdisciplinary research center to identify cost-effect methods of commercial livestock production in the annual grass-oak pine woodlands, while maintaining the integrity of the ecosystem. More recently, research objectives have expanded and diversified to include research projects making contributions to our knowledge of the patterns and processes working in this ecosystem.

Network), NEON (National Ecological Observatory↗
DOE OSTI2025

AmeriFlux FLUXNET-1F US-Prr Poker Flat Research Range Black Spruce Forest

This is the AmeriFlux Management Project (AMP) created FLUXNET-1F version of the carbon flux data for the site US-Prr Poker Flat Research Range Black Spruce Forest. This is the FLUXNET version of the carbon flux data for the site US-Prr Poker Flat Research Range Black Spruce Forest produced by applying the standard ONEFlux (1F) software. Site Description - This site is located in a blackspruce forest within the property of the Poker Flat Research Range, University of Alaska, Fairbanks. Time-lapse image of the canopy is measured at the same time to relate flux data to satellite images.

Iwahana, Go [University of Alaska, Faribanks]↗
DOE OSTI2021

Observations On Submicropulse Electron-beam Effects From Short-range Wakefields In Tesla-type Superconducting RF Cavities

aExperiments were performed at The Fermilab Accelerator Science and Technology (FAST) facility to elucidate the effects of short-range wakefields (SRWs) in TESLA-type rf cavities. FAST has a unique configuration of a photocathode rf gun beam injecting two TESLA-type single cavities (CC1 and CC2) in series prior to the cryomodule. To investigate short-range wakefield effects, we have steered the beam to minimize the signals in the higher-order mode (HOM) detectors of CC1 and CC2 for a baseline, and then selected a vertical corrector to steer the beam off axis at an angle into CC1 or CC2. A Hamamatsu synchro-scan streak camera viewing a downstream OTR screen provided an image of y-t effects within the micropulses with ~10-micron spatial resolution and 2-ps temporal resolution. At 500 pC/b, 50 b, and 2 mrad off-axis steering into CC2, we observed an ~ 100-micron head-tail centroid shift in the streak camera image y(t)-profiles. This centroid shift value is consistent wit h a calculated short-range wakefield effect using ASTRA simulations.

43 PARTICLE ACCELERATORS↗
DOE OSTI2020

DIRECT OBSERVATIONS OF SUBMICROPULSE ELECTRON-BEAM EFFECTS FROM SHORT-RANGE WAKEFIELDS IN TESLA-TYPE SUPERCONDUCTING RF CAVITIES

Experiments were performed at The Fermilab Accelerator Science and Technology (FAST) facility to elucidate the effects of short-range wakefields (SRWs) in TESLA-type rf cavities. FAST has a unique configuration of a photocathode rf gun beam injecting two TESLA-type single cavities (CC1 and CC2) in series prior to the cryomodule. To investigate short-range wakefield effects, we have steered the beam to minimize the signals in the higher-order mode (HOM) detectors of CC1 and CC2 for a baseline, and then used a vertical corrector between the two cavities to steer the beam off axis at an angle into CC2. A Hamamatsu synchroscan streak camera viewing a downstream OTR screen provided an image of y-t effects within the micropulses with ~10-micron spatial resolution and 2-ps temporal resolution. At 500 pC/b, 50 b, and 4 mrad off-axis steering into CC2, we observed an ~ 100-micron head-tail centroid shift in the streak camera image y(t)-profiles. This centroid shift value is 5 times l arger than the observed HOM-driven centroid oscillation within the macropulse, and it is consistent with a calculated short-range wakefield effect using ASTRA simulations.

43 PARTICLE ACCELERATORS↗