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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 1,063 records · Page 59
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Deciphering yield modification of hadron-triggered semi-inclusive recoil jets in heavy-ion collisions

Jet quenching is recognized as critical evidence for the existence of the quark-gluon plasma (QGP) and serves as an essential probe to study its transport properties. Measurements of hadron-triggered semi-inclusive recoil jets have gained popularity due to its capability to probe jets over an extended phase space at low transverse momenta (p T ) and large radii. Recent ALICE measurements showed that the I AA , yield ratio of recoil jets between heavy-ion and p+p collisions, rises with jet p T and exceeds unity at high p T , contradicting conventional expectations that jet quenching should result in I AA values less than one. In this contribution, we re-examine the surface bias and study the effects of energy losses for both trigger hadrons and recoil jets on I AA , employing the Linear Boltzmann Transport (LBT) model to simulate jet-medium interactions. Our findings suggest that a large portion of hadrons used for the triggers undergoes substantial energy loss, despite surface bias. In particular, the energy loss of the trigger hadrons elevates the I AA baseline, corresponding to the case of no energy loss for recoil jets, to be greatly larger than unity. This enhancement of the baseline implies that the measured I AA values being larger than unity could still signal jet quenching.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2022

Caution on Using Tetrahydrofuran for Processing Crystalline Silica Samples From Engineered Stone for XRD Analysis

Abstract We conducted laboratory experiments to investigate a suspected effect of tetrahydrofuran (THF) on quantifying crystalline silica in samples collected from working with engineered stone when THF is used to process samples prior to the X-ray diffraction (XRD) analysis. Two groups of samples from grinding either engineered stone or granite were simultaneously taken from a laboratory testing system, with one group of samples using THF for processing and another group using muffle furnace for ashing. For each stone type, we also tested four levels of respirable dust loading on the samples by varying the grinding time from 1 to 8 min. Statistical analysis of the experimental results on crystalline silica contents of the two groups of samples showed that the difference between the two methods was not significant (P ≥ 0.05) for the granite at all four levels of respirable dust loading and for the engineered stone at the two levels of respirable dust loading greater than 0.5 mg. However, the crystalline silica content from using THF processing was significantly lower (P = 0.001) than that from using muffle furnace ashing for engineered stone when the respirable dust loading levels were less than 0.5 mg. For the engineered stone dust samples with grinding times of 1 and 2 min, the average respirable dust loading was about 0.19 and 0.34 mg, respectively; while the crystalline silica content from using THF processing was 30.9 and 21.5% lower than that from using muffle furnace ashing, respectively. Since most full-shift samples from field assessments in this industry are expected to have respirable dust loading less than 0.5 mg, muffle furnace or radio frequency plasma ashing should be specified as the preferred sample processing method instead of the THF processing method for quantification of crystalline silica when engineered stone is expected to present to avoid artificially reduced silica content values, which are likely caused by the reactions between THF and the resins in engineered stone.

Public, Environmental & Occupational Health↗
DOE OSTI2021

Technoeconomic Design of a Geothermal-Enabled Cold Climate Zero Energy Community

Development of a zero energy community is more costly in northern cold climates than in moderate regions. Building energy loads are higher, thanks to the colder weather, and site solar photovoltaics (PV) are less productive due to lower solar incidence and misalignment with the buildings’ energy needs (summer production, winter demands). Geothermal energy production can support a zero energy community through application of energy efficiency (demand design), geothermal production (supply design), and asset dispatch as an integrated techno-economic package. This article presents the process used to explore geothermal system integration, our findings, and technical challenges for community-scale adoption of geothermal as an electric and thermal resource. We show that under a wide range of conditions, community-scale geothermal electric power and direct-use thermal energy is economically competitive with “business-as-usual” design and construction practices for zero energy communities. Furthermore, geothermal-produced energy will be self-consumed to a much greater extent than PV, resulting in significant reductions in site energy import and export. We conclude that under appropriate conditions, community-scale geothermal can be the most economically favorable energy resource for northern-climate zero energy community developments. Ongoing geothermal research and development to improve performance and reduce costs will further enhance the value proposition for community-scale geothermal technologies. We expect that including geothermal power and thermal energy in zero energy community design can improve its cost-effectiveness and therefore enhance the benefits of zero energy in more northern climates.

15 GEOTHERMAL ENERGY↗
DOE OSTI2023

False Indications of Dose-Response Nonlinearity in Large Epidemiologic Cancer Radiation Cohort Studies; A Simulation Exercise

This study explores the likely prevalence of false indications of dose-response nonlinearity in large epidemiologic cancer radiation cohort studies (A-bomb survivors, INWORKS, Techa River). Reasons: Increasing numbers of tests of nonlinearity are being made in studies. Hypothesized nonlinear dose-response models have been justified to policy makers by analyses that rely in part on isolated findings that could be statistical fluctuations. After removing dose nonlinearity (linearization) by adjusting person-years of observation at each dose category, indications of nonlinearity, necessarily false, were counted in 5,000 randomized replications of six datasets. The average frequency of any false positive for five indicators of nonlinearity tested against a linear null was roughly 25% in Monte Carlo simulations per study, consistent with binomial calculations, increasing to ~50% within 6 studies assessed. Comparable frequencies were found using Akaike's information criterion (AIC) for model selection or multi-model averaging. False above-zero threshold doses were found more than 50% of the time, averaging to 0.05 Gy, consistent with findings in the 6 studies. Such bias, uncorrected, could distort meta-analyses of multiple studies, because meta-analyses can incorporate high P value findings. AIC-based correction for the extra threshold parameter lowered these false occurrences to 8 to 19%. Given the simulation rates, the possibility of false positives might be noted when isolated findings of nonlinearity are discussed in a regulatory context. When reporting a threshold dose with a P value > 0.05, it would be informative to note the expected high false prevalence rate due to bias.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2021

CO 2 and Renewable Electricity into Chemicals: Formic Acid Production from Coal Flue Gas

Formic acid (FA) is an industrial chemical. It is used as a preservative for silage, as a digestive aid for animals, as a fluid for fracking, as a pharmaceutical intermediate and in leather tanning. The global formic acid market is valued at 777.4 million USD in 2020 and is expected to reach 851.8 million USD by the end of 2026. A new major formic acid application is the use of formic acid as a key feedstock for the bioprocessing industry. It has the potential to grow tremendously if we can lower the cost of formic acid production compared with the current fossil-fuel one. Recently, Dioxide Materials has developed a technology that can directly convert CO 2 to pure formic acid with a three-compartment CO 2 electrolyzer. However, the electrolyzer performance needs further improvement for the technology to be commercially viable. The major objective of this project is to develop the electrolyzer technology to enable formic acid as a feedstock for the bioprocessing industry to be economically manufactured from flue gas from a coal fired pilot plant. In particular, the project is to understand how to run the electrolyzer for the conversion of CO 2 into formic acid using flue gas from a coal fired power plant as a source of CO 2 . The work will include characterizing how the performance of the electrolyzer changes with low CO 2 concentration and impurities, developing new cell designs that can still operate with feedstocks with low CO 2 concentrations, testing simulated flue gas in the electrolyzer system and developing filters to remove any impurities that arise.

01 COAL, LIGNITE, AND PEAT↗
DOE OSTI2023

Main Bearing Replacement and Damage - A Field Data Study on 15 Gigawatts of Wind Energy Capacity

This study seeks to establish a comprehensive baseline of knowledge for the replacement and damage of main bearings in wind turbines. The purpose of this report is to provide a high-level summary of the data set, methodology, and results of this work. Full technical details and an extended analysis will be made available in a future publication. We collected data on main bearing replacements and reported damage from industrial partners based in Europe and the United States. In total, we obtained data for 167 wind power plants, with a combined capacity of 15.3 gigawatts (GW). Most of the data set was comprised of land-based, three-point mount, spherical roller bearings. Within this data set were 689 instances of main bearing replacement. Analysis was undertaken in two parts: first, a statistical analysis of the main bearing time-to-replacement data using survival analysis techniques; second, quantitative and qualitative analyses of the obtained damage information. Our results showed that 10% of a fixed main bearing population would be expected to have been replaced by 10.5 years. This is close to half of the 20-year design value. Fitted parametric distributions then indicated that by year 20, between 22% and 25% of main bearings are expected to have been replaced. Analysis of the damage reports revealed spalling to be the main type of damage listed. The additional presence of surface damage in the collected data indicates that at least part of the spalling cases are likely due to surface-initiated rolling contact fatigue. At this stage is not clear what proportion of spalling cases result from "wear induced", surface-initiated and subsurface-initiated rolling contact fatigue. While this work provides important insights into the current state of main bearing replacements and damage, many questions remain. An ongoing and expanding data collection and analysis effort focused on wind turbine main bearings is therefore recommended.

17 WIND ENERGY↗
NASA NTRS1972

The transverse Poisson's ratio of composites.

An expression is developed that makes possible the prediction of Poisson's ratio for unidirectional composites with reference to any pair of orthogonal axes that are normal to the direction of the reinforcing fibers. This prediction appears to be a reasonable one in that it follows the trends of the finite element analysis and the bounding estimates, and has the correct limiting value for zero fiber content. It can only be expected to apply to composites containing stiff, circular, isotropic fibers bonded to a soft matrix material.

Foye, R. L.↗
NASA NTRS1980

Comparison of ISEE-1 and -3 interplanetary magnetic field observations

Three hourly correlation coefficients and the lag at maximum correlation are computed using one minute averages of ISEE-1 and -3 magnetometer data during the period in which ISEE-3 moved from the earth to its halo orbit around the libration point. The maximum correlation coefficients are highly variable ranging from close to zero to almost unity. The lags, while on the average approximating the expected corotation delay, have very large departures from this value. These results suggest that the normals to the planes separating fields of differing orientation often make large angles to the ecliptic plane and/or that the interplanetary magnetic field has a significant amount of bending on a scale length the order of 200 earth radii. Furthermore, there often appears to be a significant amount of propagating structure in the IMF. Thus, ISEE-3 magnetic field measurements should be used with caution if precise timing of arrival at the earth or precise directions of the field upon arrival are important.

Russell, C. T.↗
NASA NTRS1981

Dust emission from comets at large heliocentric distances. I - The case of comet Bowell /1980b/

Alternative processes of dust emission from comets at large heliocentric distances are considered, in order to explain the dust coma observed in comet Bowell (1980b) at a heliocentric distance as large as 7.17 AU. It is shown that the electrostatic blow-off of dust from a charged, H2O-dominated nucleus having a layer of loose, fine dust may be the formation process of the dust coma, with the coma size expected from the process being comparable to the observed value and the dust grain size being equal to or less than 0.4 microns in size. The upper limit for the total mass in the coma is 3.9 x 10 to the 8th g, and the spatial extension less than 10,000 km. The observed activity may alternatively be due to dust entrainment by the sublimating gas from a CO2-dominated nucleus.

Houpis, H. L. F.↗
NASA NTRS1983

A new technique for measuring gas conversion factors for hydrocarbon mass flowmeters

A technique for measuring calibration conversion factors for hydrocarbon mass flowmeters was developed. It was applied to a widely used type of commercial thermal mass flowmeter for hydrocarbon gases. The values of conversion factors for two common hydrocarbons measured using this technique are in good agreement with the empirical values cited by the manufacturer. Similar agreements can be expected for all other hydrocarbons. The technique is based on Nernst theorem for matching the partial pressure of oxygen in the combustion product gases with that in normal air. It is simple, quick and relatively safe--particularly for toxic/poisonous hydrocarbons.

Singh, J. J.↗
NASA NTRS1983

Dielectronic recombination rates, ionization equilibrium, and radiative emission rates for Mn ions in low-density high-temperature plasmas

The analysis of optically-thin far-ultraviolet and X-ray emission lines of multiply-charged ions is one of the basic methods for determining the temperatures and densities of laboratory and astrophysical plasmas. In addition, the energy balance in these plasmas can be significantly influenced by the emission of radiation from relatively low concentrations of multiple-charged atomic ions. Because the populations of the excited levels are expected to depart substantially from their local thermodynamic equilibrium values a detailed treatment of the elementary collisional and radiative processes must be employed in order to predict the emission line intensities. In this investigation the authors present the results of calculations based on a corona equilibrium model in which a detailed evaluation is made of the dielectronic recombination rate coefficients. The ionization and autoionization following inner-shell electron excitation from each ground state are balanced by direct radiative and dielectronic recombination. The spectral line intensities emitted by the low-lying excited states, which are assumed to undergo spontaneous radiative decay in times that are short compared with the collision time, are evaluated in terms of the corona ionization equilibrium distributions of the ground states and their electron-impact excitation states.

Jacobs, V. L.↗
NASA NTRS1984

Comparative study of the loss cone-driven instabilities in the low solar corona

A comparative study of the loss cone-driven instabilities in the low solar corona is undertaken. The instabilities considered are the electron cyclotron maser, the whistler, and the electrostatic upper hybrid. It is shown that the first-harmonic extraordinary mode of the electron cyclotron maser instability is the fastest growing mode for strong magnetized plasma (the ratio of plasma frequency to cyclotron frequency being less than 0.35). For values of the ratio between 0.35 and 1.0, the first-harmonic ordinary mode of the electron cyclotron maser instability dominates the emission. For ratio values greater than 1.0, no direct electromagnetic radiation is expected since other instabilities, which do not escape directly, saturate the electron cyclotron maser (the whistler or the electrostatic upper hybrid waves). It is also shown that the second-harmonic electron cyclotron maser emission never grows to an appreciable level. Thus, it is suggested that the electron cyclotron maser instability can be the explanation for the escape of the first harmonic from a flaring loop.

Sharma, R. R.↗
NASA NTRS1984

Bolometers operated at 0.1 K and 0.2 K cooled by adiabatic demagnetization

The construction of bolometers operating at temperatures of 0.1 K and 0.2 K and cooled by adiabatic demagnetization is reported. The electrical noise-equivalent power (NEP) of the bolometers was found to be 1.8 and 6.6 x 10 to the -16th W/sq rt Hz, respectively. These values are within a factor of two of the expected performance based upon bolometer theory. The thermistor material used was gallium-doped single-crystal germanium, for which a resistivity temperature dependence is found.

Lesyna, L.↗
NASA NTRS1986

Planetary Fabry-Perot spectroscopy

Uranus and Jupiter HD/H2 spectra determine bulk D/H ratios which are significantly different from theoretical expectations, with the Uranus D/H about half the Jovian value. Feasibility of Mars photochemistry study with a PEPSIOS spectrometer was demonstrated with visible band O2, H2O, and CO2 spectra; and near infrared (1.57 micron) spectra of CO and CO2; and NASA/IRTF observations have been proposed in support of the Mars Observer mission objectives. Analysis of monochromatic images clearly resolve the azimuthal and radial structure in the Jovian nebula (ion partitioning, temperature structure, ion/neutral interactions), adding a unique and important post-Voyager perspective and providing a baseline for forthcoming Galileo experiments. Simultaneous ground based and IUE observations of Jovian nebula are under analysis. Doppler resolved image sequences (data cubes) of Io sodium neutrals clearly isolate the high velocity charge exchange jet, a sensitive ground-based probe of the tenuous neutral atmosphere of Io.

Trauger, J. T.↗
NASA NTRS1989

Effects of lateral viscosity variations on long-wavelength geoid anomalies and topography

The effects of lateral variations in the earth mantle viscosity, due to temperature- or stress-dependent rheology, on the long-wavelength geoid anomalies are examined. Results from simple perturbation theory combined with findings from numerical models for convective flow led to a conclusion that the geoid due to the very longest wavelength convective patterns (l = 2,3) on earth is probably not seriously contaminated by lateral variations due either to temperature or stress dependence. Considerable contamination of the higher-degree geoid (l value of no less than 4) is to be expected due to lateral viscosity variations in phase with the fundamental convection scale length.

Richards, Mark A.↗
NASA NTRS1991

Planetary accretion rates - Analytical derivation

New analytical formulae that are valid even in cases where Keplerian shear determines the approach velocity in planetary accretion rates are presently shown to accurately reproduce Monte Carlo study results. The formulae yield accretion rates over a great variety of planet formation-conducive conditions. Since the absolute values of impact rates yielded by the formulae were expected to have factor-of-2-to-3 uncertainties, the good agreement with Monte Carlo experiments obtained suggests the reasonableness of many of the estimates adopted, or the mutual cancelling-out of various uncertainties.

Greenberg, Richard↗
NASA NTRS1992

Preliminary results of a balloon flight of the solar disk sextant

Preliminary results of a balloon flight on October 11, 1991, of the solar disk sextant (SDS) experiment are reported. The SDS is an instrument which measures the solar diameter at different orientations with respect to the solar polar axis. Fitting straight lines through two fixed-angle data sets with time as the independent variable yields slopes of (7.1 +/ - 1.5) x 10 exp -3 and (6.7 +/- 1.6) x 10 exp -3/mas s, consistent with the value of 6.47 x 10 exp -3/mas s expected from the earth's approach to the sun due to the orbital motion toward perihelion. Upon the instrument's rotation on its axis a sinusoidal component of the diameter measurement was observed in each rotation cycle, with a variable amplitude of about 150 mas. The present result is epsilon of (5.6 +/- 6.3) x 10 exp -6, about 30 deg offset from the polar-equator position. The absolute diameter obtained by means of the FFT definition is found to be 1919.269 +/- 0.240 arcsec or 1919.131 +/- 0.240 arcsec, depending on the orientation mode of the measurement.

Maier, E.↗
NASA NTRS1984

Phase 2 development of Great Lakes algorithms for Nimbus-7 coastal zone color scanner

A series of experiments have been conducted in the Great Lakes designed to evaluate the application of the NIMBUS-7 Coastal Zone Color Scanner (CZCS). Atmospheric and water optical models were used to relate surface and subsurface measurements to satellite measured radiances. Absorption and scattering measurements were reduced to obtain a preliminary optical model for the Great Lakes. Algorithms were developed for geometric correction, correction for Rayleigh and aerosol path radiance, and prediction of chlorophyll-a pigment and suspended mineral concentrations. The atmospheric algorithm developed compared favorably with existing algorithms and was the only algorithm found to adequately predict the radiance variations in the 670 nm band. The atmospheric correction algorithm developed was designed to extract needed algorithm parameters from the CZCS radiance values. The Gordon/NOAA ocean algorithms could not be demonstrated to work for Great Lakes waters. Predicted values of chlorophyll-a concentration compared favorably with expected and measured data for several areas of the Great Lakes.

Tanis, Fred J.↗