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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 217 records · Page 12
All sourcesNASA NTRSDOE OSTI
NASA NTRS1988

Energetic electrons in impulsive and extended solar flares as deduced from flux correlations between hard X-rays and microwaves

The peak flux relationship between hard X-rays and microwaves from solar flares is studied using about 400 events simultaneously recorded with the hard X-ray burst spectrometer on the SMM satellite and the Nobeyama 17 GHz radiometer. The data indicate that the hard X-ray and microwave peak fluxes correlate best for X-ray energies of less than about 80 keV for impulsive flares and greater than about 360 keV for extended flares. By postulating that electrons responsible for microwave emission at 17 GHz are those emitting hard X-rays at these photon energies, it is concluded that: (1) in impulsive flares, microwaves at about 20 GHz are emitted mainly by electrons of less than about 200 keV from a layer through which the electrons stream down into the thick-target hard X-ray source; and (2) in extended flares, microwaves are emitted mainly by MeV electrons trapped in a coronal loop or loops.

Kosugi, Takeo↗
DOE OSTI2024

CAD-based Energy & Cost Models Prove Affordable Net Zero Energy Performance for WonderWindows + 24" On-center Framing

Windows are thermally the “weakest link” in the building envelope. Increasing the thermal resistance of windows can make buildings more energy efficient and reduce the cost of electricity needed for conditioning the building. The proper design and placement of framing can also help to reduce the thermal bridging that occurs near the window frame area. This study investigates the energy performance of multi-pane acrylic windows fitting 24" on-center framing. Initial parametric analysis is done for a single zone accessory dwelling unit (ADU). Then, an energy model was developed for three types of wood-framed buildings: townhomes, stacked flats and hotels. A whole building energy simulation is performed for each of these building types in hot-humid Houston, mixed-humid New York, and cold-humid Minneapolis climates. The results show up to a 39% reduction in heating, ventilation, and air-conditioning (HVAC) related electricity consumption for the cold climate compared to the Base case which has window and wall properties based on ASHRAE standard 90.1 2019. In the hot climate, a modest increase in electricity consumption was seen due to an increase in cooling electricity demand. The ADU achieved Net Zero Energy performance in all 3 Climate Zones despite having the highest exterior surface area-to-floor area ratio: the ADU also had the highest PV kW to floor area ratio compared to the other multi-story building types. The townhomes, hotel and stacked flats respectively met 73, 52 and 57 % of electrical use in Houston, 71, 48 and 56 % in New York, and 63, 40 and 53 % in Minneapolis from energy produced by rooftop solar. If 400 W solar panels are used instead of 320 W panel used for energy simulation, it is estimated that in the townhomes, hotel and stacked flats rooftop solar can meet 91, 65 and 71 % of electrical use in Houston; 89, 60 and 70% in New York, and 79, 50 and 66 % in Minneapolis. A preliminary evaluation of cost shows that such superior performance can potentially be achieved at less first cost with this 24"on-center solution than conventional construction. All the building types at the three locations used for simulation had net energy use intensity under 20 kBtu/sf/year with 320 W solar panel and under 17 kBtu/sf/year with 400 W solar panel. Further tailoring of building envelope R-values and window solar heat gain to particular Climate Zone locations for each building type shows promise in reducing the HVAC electricity use that comprises almost half of building energy use.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2025

Enhanced Phase Stability of Sm 2 (Fe, Al) 17 C x

Aluminum doping can improve the phase stability of metastable compound Sm 2 Fe 17 C x with a high carbon content (x > 1.5). We investigated the preferential site substitution of Al, chemical bonding, and structural stability in Sm 2 (Fe,Al) 17 C 3 using first-principle calculations. Our results reveal a strong correlation between the preferential substitution of Fe by Al and the atomic site chemical environment, which affects the overall phase stability. Specifically, Al preferentially occupies the 9d site in Sm 2 (Fe,Al) 17 C 3 . At the same time, Al prefers the site 6c in its parent phase Sm 2 (Fe,Al) 17 . Partial replacement of Fe with Al leads to a more negative formation energy, indicating enhanced thermodynamic stability. Crystal Orbital Hamilton Population (COHP) and Crystal Orbital Bond Index (COBI) analysis suggest that insertion of carbon weakens the bonding strength of Sm-Fe (18f) and Sm-Fe (18h), resulting in metastability of Sm 2 Fe 17 C x . Doping Al strengthens Al-Fe, Al-Sm, Sm-Fe (18f, 18h) and Fe–C bonding in Sm 2 (Fe,Al) 17 C 3 , as revealed by calculated COHP and COBI. These effects contribute to improved phase stability in the Al-doped 2:17 interstitial compound.

chemical bonding↗
DOE OSTI2021

AmeriFlux FLUXNET-1F US-Tw1 Twitchell Wetland West Pond

This is the AmeriFlux Management Project (AMP) created FLUXNET-1F version of the carbon flux data for the site US-Tw1 Twitchell Wetland West Pond. This is the FLUXNET version of the carbon flux data for the site US-Tw1 Twitchell Wetland West Pond produced by applying the standard ONEFlux (1F) software. Site Description - The Twitchell Wetland site is a 7.4-acre restored wetland on Twitchell Island, that is managed by the California Department of Water Resources (DWR) and the U.S. Geological Survey (USGS). In the fall of 1997, the site was permanently flooded to a depth of approximately 25 cm. The wetland was almost completely covered by cattails and tules by the third growing season. A flux tower equipped to analyze energy, H2O, CO2, and CH4 fluxes was installed on May 17, 2012.

Valach, Alex↗
DOE OSTI2022

AmeriFlux FLUXNET-1F US-Tw5 East Pond Wetland

This is the AmeriFlux Management Project (AMP) created FLUXNET-1F version of the carbon flux data for the site US-Tw5 East Pond Wetland. This is the FLUXNET version of the carbon flux data for the site US-Tw5 East Pond Wetland produced by applying the standard ONEFlux (1F) software. Site Description - The Twitchell Wetland site is a 6.5 acre restored wetland on Twitchell Island, that is managed by the California Department of Water Resources (DWR) and the U.S. Geological Survey (USGS). In the fall of 1997, the site was permanently flooded to a depth of approximately 55 cm. The wetland remained fairly unvegetated in patches increasing in size towards the east. The site underwent a major disturbance in 2013 when the vegetation was removed to seed a nearby restored wetland. A flux tower equipped to analyze energy, H2O, CO2, and CH4 fluxes was installed on April 17, 2018.

Valach, Alex↗
DOE OSTI2021

Statistical Hauser-Feshbach model calculation for (α, n) reaction cross section and discrete level population

We calculate the α-particle induced reactions on 17,18 O, 19 F, and 23 Na, in the energy range 0 ≤ E α ≤ 10 MeV, with a particular attention to the branching ratios of populated discrete levels in the (α,n) channels. Since there are too many open channels to employ the R-matrix theory, we apply the statistical Hauser-Feshbach model to calculate these reaction cross sections and branching ratios. The branching ratio is defined as b n = $\frac{σ_n}{Σ_iσ_i + σ_c}$ , where σ n is the n-th level production cross section after the neutron emission, and σ c is the production of the continuum state. In the cases of our target nuclei and the energy range of interest, the residual nuclei of the neutron emission channel are always in their discrete states, so that σ c can be negligible.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
NASA NTRS1974

Application of the integrated utilities concept to community-size developments

It is shown that the modular integrated utility systems (MIUS) concept (combining the utility services of electrical power, heating and cooling, water supply and waste water treatment, and solid waste management into a single local plant) can be applied to community-size developments with major benefits of energy (fossil fuels) savings, reduction in solid waste haul-off quantity, and reduction in fresh water demand. Compared to a conventional utilities system, MIUS energy and water savings are found to reach 38 and 17%, respectively. Effluent and solid waste load reduction attain 17 and 80%, respectively. These benefits are obtainable through use of commercially available hardware and at costs competitive with conventional utilities.

Redding, T. E.↗
NASA NTRS1980

A survey of He-3 enriched events between 1974 and 1978

In five years of observations between 1974 and 1978, at least 17 He-3 enriched events have been identified in the energy range 2 to 13 MeV/nucleon, with He-3/He-4 ratios ranging from less than 0.1 to greater than 4. The scarcity of H-2 in He-3 events found by other workers is confirmed in this data. Flattening of He-3 spectra relative to He-4 is identified in several of the events. Many but not all of the sampled events are found to have small H-1/He-4 ratios. A sum of the sampled events shows not only Fe enrichments but abundances enhanced relative to oxygen of all heavier elements. No substantial depletion of carbon is identified. A dependence of the enhancements in He-3 events on atomic number like that found in other Fe-enriched solar cosmic ray events suggests a common mechanism producing the enhancements.

Mcguire, R. E.↗
NASA NTRS1992

Energy transformations associated with the synoptic and planetary scales during the evolution of a blocking anticyclone and an upstream explosively-developing cyclone

The eddy kinetic energy (KE), release of eddy potential energy, generation of eddy kinetic energy, and exchange between eddy and zonal kinetic energy are investigated for a blocking anticyclone over the North Atlantic Ocean and an extratropical cyclone that developed during January 17-21, 1979. The results indicate that KE was maintained by baroclinic conversion of potential to kinetic. As released potential energy was being used to generate KE, a portion of the KE was barotropically converted to zonal KE. These transformations were dominated by the synoptic-scale component. While changes in the mass field depended not only on the synoptic scale but also on the interactions between the synoptic and planetary scales, the corresponding changes in the eddy motion fields responded largely to synoptic-scale processes.

Smith, Phillip J.↗
NASA NTRS1996

Friction and Wear Properties of As-Deposited and Carbon Ion-Implanted Diamond Films

Recent work on the friction and wear properties of as-deposited and carbon ion-implanted diamond films was reviewed. Diamond films were produced by the microwave plasma chemical vapor deposition (CVD) technique. Diamond films with various grain sizes and surface roughnesses were implanted with carbon ions at 60 keV ion energy, resulting in a dose of 1.2 x 10(exp 17) carbon ions per cm(exp 2). Various analytical techniques, including Raman spectroscopy, proton recoil analysis, Rutherford backscattering, transmission and scanning electron microscopy, X-ray photoelectron spectroscopy, and X-ray diffraction, were utilized to characterize the diamond films. Sliding friction experiments were conducted with a polished natural diamond pin in contact with diamond films in the three environments: humid air (40% relative humidity), dry nitrogen (less than 1 percent relative humidity), and ultrahigh vacuum (10(exp -7) Pa). The CVD diamond films indeed have friction and wear properties similar to those of natural diamond in the three environments. The as-deposited, fine-grain diamond films can be effectively used as self-lubricating, wear-resistant coatings that have low coefficients of friction (0.02 to 0.04) and low wear rates (10(exp -7) to lO(exp -8) mm(exp 3) N(exp -1) m(exp -1)) in both humid air and dry nitrogen. However, they have high coefficients of friction (1.5 to 1.7) and a high wear rate (10(exp -4) mm(exp 7) N(exp -1) m(exp -1)) in ultrahigh vacuum. The carbon ion implantation produced a thin surficial layer (less than 0.1 micron thick) of amorphous, non-diamond carbon on the diamond films. In humid air and dry nitrogen, the ion-implanted, fine and coarse-grain diamond films have a low coefficient of friction (around 0.1) and a low wear rate (10(exp -7) mm(exp 3) N(exp -1) m(exp-1)). Even in ultrahigh vacuum, the presence of the non-diamond carbon layer reduced the coefficient of friction of fine-grain diamond films to 0.1 or lower and the wear rate to 10(exp -6) mm(exp 3) N(exp -1) m(exp -1). Thus, the carbon ion-implanted, fine-grain diamond films can be effectively used as wear-resistant, self-lubricating coatings not only in air and dry nitrogen, but also in ultrahigh vacuum.

Miyoshi, Kazuhisa↗
NASA NTRS1999

A Highly Doppler Blueshifted Fe-K Emission Line in the High-Redshift QSO PKS 2149-306

We report the results from an ASCA observation of the high-luminosity, radioloud quasar PKS 2149-306 (redshift 2.345), covering the approximately 1.7 - 30 keV band in the quasar-frame. We find the source to have a luminosity of approximately 6 x 10(exp 47) ergs/s in the 2 - 10 keV band (quasar frame). We detect an emission line centered at approximately 17 keV in the quasar frame. Line emission at this energy has not been observed in any other active galaxy or quasar to date. We present evidence rejecting the possibility that this line is the result of instrumental artifacts, or a serendipitous source. The most likely explanation is blueshifted Fe-K emission (the equivalent width, is EW approximately 300 +/- 200 eV, quasar frame). Bulk velocities of the order of 0.75c are implied by the data. We show that Fe-K line photons originating in an accretion disk and Compton-scattering off a leptonic jet aligned along the disk axis can account for the emission line. Curiously. if the emission-line feature recently discovered in another quasar (PKS 0637-752, z = 0.654) at 1.6 keV in the quasar frame, is due to blueshifted OVII emission, the Doppler blueshifting factor in both quasars is similar (approximately 2.7 - 2.8).

Yaqoob, Tahir↗
DOE OSTI2026

Operational Parameter Database for Molten Salt Thermal Energy Storage Tank Modeling

The second generation of concentrated solar power (CSP) plants is characterized by the use of a central receiver (either cavity or external), two molten nitrate salt tanks (60 wt.% NaNO 3 and 40 wt.% KNO 3 ), and a steam Rankine power-generation cycle connected through a primary heat exchanger. Molten salt thermal energy storage (TES) tanks have been widely deployed in commercial CSP plants worldwide and have been essential for increasing plant dispatchability and capacity factor, while also reducing the levelized cost of electricity (LCOE). These systems enable energy storage at the gigawatt-hour scale, typically providing 6 to 17 hours of storage duration. Despite being a commercial technology, the multiple failures observed after only a few months or years of operation in plants around the world demonstrate the technology's relative infancy and highlight the need for further research to improve its reliability. The National Laboratory of the Rockies (NLR), in collaboration with industry partners and academic and research institutions, has been leading multiple projects funded by the U.S. Department of Energy (DOE). These projects focus on addressing molten salt tank failures by improving tank design and welding fabrication practices, evaluating new alloys and weld fillers, and providing guidelines for tank commissioning and safe operation. In particular, this report presents modeling results on the effect of key tank operation parameters during 60 minutes of operation, including the mass flow rate and temperature of the salt inflow, tank salt inventory temperature, and inventory level for a representative molten salt tank design. These results form a database of tank operation behaviors that captures the effects of each specific parameter during charging, charging/discharging, and discharging processes.

14 SOLAR ENERGY↗
DOE OSTI2021

MuSIC@Indiana: An effective tool for accurate measurement of fusion with low-intensity radioactive beams

The design, construction, and characterization of the Multi-Sampling Ionization Chamber, MuSIC@Indiana, are described. This detector provides efficient and accurate measurement of the fusion cross-section at near-barrier energies. The response of the detector to low-intensity beams of 17,18 O, 19 F, 23 Na, 24,26 Mg, 27 Al, and 28 Si at E lab 50–60MeV was examined. MuSIC@Indiana was commissioned by measuring the 18 O+ 12 C fusion excitation function for 11 < E cm < 20 MeV using CH 4 gas. Here, a simple, effective analysis cleanly distinguishes proton capture and two-body scattering events from fusion on carbon. With MuSIC@Indiana, measurement of 15 points on the excitation function for a single incident beam energy is achieved. The resulting excitation function is shown to be in good agreement with literature data.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2024

10th Jubilee Singlet Fission Workshop

Singlet fission and its potential utility in solar photoconversion is a rapidly expanding field of scientific research. The workshop funded by this award was for facilitating collaboration and for open sharing of recent experimental or theoretical results on topics relevant to singlet fission. It took place at Estes Park Colorado at the Dao House resort on June 17 -20, 2023.

14 SOLAR ENERGY↗
DOE OSTI2021

On wavelength-dependent exciton lifetime distributions in reconstituted CP29 antenna of the photosystem II and its site-directed mutants

To provide more insight on the excitonic structure and exciton lifetimes of the wild type (WT) CP29 complex of Photosystem II (PSII) we measured high-resolution (low temperature) absorption, emission, and hole burned spectra for the A2 and B3 mutants, which lack chlorophylls a612 and b614 (Chls), respectively. Experimental and modeling results obtained for the WT CP29 and A2/B3 mutants provide new insight on the mutation-induced changes at the molecular level and shed more light on energy transfer dynamics. Simulations of the A2 and B3 optical spectra, using the second-order non-Markovian theory, and comparison with improved fits of WT CP29 optical spectra, provide more insight on their excitonic structure, mutation induced changes, and frequency-dependent distributions of exciton lifetimes (T 1 ). A new Hamiltonian obtained for WT CP29 reveals that deletion of Chls a612 or b614 induces changes in the site-energies of all remaining Chls. Hamiltonians obtained for A2 and B3 mutants are discussed in the context of the energy landscape of chlorophylls, excitonic structure and the transfer kinetics. Our data suggest that the lowest exciton states in A2 and B3 mutants are contributed by a611(57%), a610(17%), a615(15%) and a615(58%), a611(20%), a612(15%) Chls, respectively, although other compositions of lowest energy states are also discussed. Lastly, we argue that the calculated exciton decay times are consistent with both the hole-burning and recent transient absorption measurements. Wavelength-dependent T 1 distributions offer more insight into the interpretation of kinetic traces commonly described by discrete exponentials in global analysis/global fitting of transient absorption experiments.

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

Search for a massless dark photon in c → u γ ′ decays

Using 7.9 f b − 1 of e + e − collision data collected at s = 3.773 GeV with the BESIII detector at the BEPCII collider, we search for the massless dark photon with the flavor-changing neutral current processes D 0 → ω γ ′ and D 0 → γ γ ′ for the first time. No significant signals are observed, and the upper limits at the 90% confidence level on the massless dark photon branching fraction are set to be 1.1 × 10 − 5 and 2.0 × 10 − 6 for D 0 → ω γ ′ and D 0 → γ γ ′ , respectively. These results provide the most stringent constraint on the new physics energy scale associated with c u γ ′ coupling in the world, with the new physics energy scale related parameter | C | 2 + | C 5 | 2 < 8.2 × 10 − 17 GeV − 2 at the 90% confidence level. Published by the American Physical Society 2025

Ablikim, M.↗
DOE OSTI2023

DESI Survey Validation Spectra Reveal an Increasing Fraction of Recently Quenched Galaxies at z ∼ 1

Abstract We utilize ∼17,000 bright luminous red galaxies (LRGs) from the novel Dark Energy Spectroscopic Instrument Survey Validation spectroscopic sample, leveraging its deep (∼2.5 hr galaxy −1 exposure time) spectra to characterize the contribution of recently quenched galaxies to the massive galaxy population at 0.4 < z < 1.3. We use Prospector to infer nonparametric star formation histories and identify a significant population of recently quenched galaxies that have joined the quiescent population within the past ∼1 Gyr. The highest-redshift subset (277 at z > 1) of our sample of recently quenched galaxies represents the largest spectroscopic sample of post-starburst galaxies at that epoch. At 0.4 < z < 0.8, we measure the number density of quiescent LRGs, finding that recently quenched galaxies constitute a growing fraction of the massive galaxy population with increasing look-back time. Finally, we quantify the importance of this population among massive ( log ( M ⋆ / M ⊙ ) > 11.2) LRGs by measuring the fraction of stellar mass each galaxy formed in the gigayear before observation, f 1 Gyr . Although galaxies with f 1 Gyr > 0.1 are rare at z ∼ 0.4 (≲0.5% of the population), by z ∼ 0.8, they constitute ∼3% of massive galaxies. Relaxing this threshold, we find that galaxies with f 1 Gyr > 5% constitute ∼10% of the massive galaxy population at z ∼ 0.8. We also identify a small but significant sample of galaxies at z = 1.1–1.3 that formed with f 1 Gyr > 50%, implying that they may be analogs to high-redshift quiescent galaxies that formed on similar timescales. Future analysis of this unprecedented sample promises to illuminate the physical mechanisms that drive the quenching of massive galaxies after cosmic noon.

79 ASTRONOMY AND ASTROPHYSICS↗