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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 559 records · Page 31
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Hydroxyl radical yields in the heavy ion radiolysis of water

The yields of hydroxyl radicals in the radiolysis of water with protons and carbon ions have been examined using experimental scavenging techniques coupled with Monte Carlo track simulations. Combined with previous results using helium ions, this set of data gives valuable information on the potential for radiation induced damage to biological systems for light ions with very different track structures. Carbon dioxide production from aerated formic acid solutions in concentrations ranging from 10 -3 to 1 M was used as a probe of hydroxyl radical yields from about 8 ns to 8 µs. Numerical interpolation of the results at slightly different ion energies in combination with data from gamma radiolysis allows for a systematic analysis of both track average and track segment yields. As expected, considerable track chemistry is found to occur on the nanosecond to microsecond time scales. Monte Carlo track simulations employing stochastic diffusion-kinetic calculations of product yields are found to reproduce experimental observations satisfactorily. The track simulations are used to extract hydroxyl radical kinetics in pure water at neutral conditions.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2014

Energy yield loss caused by dust deposition on photovoltaic panels

Large-scale solar plants are generally located in semi-arid and desert lands where abundant sunlight is available for solar energy con- version. These plants, however, suffer from two major environmental degradation factors: high ambient temperature and high concen- tration of atmospheric dust. Degradation of solar collectors’ performance caused by soiling results in a considerable loss of energy yield in all solar plants of the world. Dust and other particulate accumulation on solar collectors causes transmission loss. This is true with respect to transmission losses in photovoltaic (PV) and concentrated photovoltaic (CPV) systems, and for reflection losses in concen- trated solar power (CSP) systems. We present here a brief review of the energy yield losses caused by dust deposition on solar collectors, with particular emphasis on flat-panel photovoltaic (PV) systems. The review includes some of the major studies reported on energy-yield losses on solar plants in operation in several regions of the world. In addition, laboratory-soiling studies are also included. We report on degradation in the performance of solar plants based on the type of solar collectors, geographical location, local climate, and exposure period of the collectors absent any manual cleaning. An analysis of the advantages of cleaning processes that include natural, manual, automatic, and passive methods is presented. Our objective is to provide solar plant designers with a database for predicting anticipated soiling losses in different parts of the world, and for assessing effective cleaning methods for restoring a system’s energy yield.

14 SOLAR ENERGY↗
DOE OSTI2018

Molecular Hydrogen Yields from the Alpha Self-Radiolysis of Nitric Acid Solutions Containing Plutonium or Americium

The yield of molecular hydrogen, as a function of nitric acid concentration, from the a-radiolysis of aerated nitric acid and sulfuric acid mixtures containing plutonium or americium has been investigated. Comparison of experimental measurements with predictions of a Monte Carlo radiation track chemistry model shows that, in addition to scavenging of the hydrated electron, its precursor, and the hydrogen atom, the quenching of excited state water is important in controlling the yield of hydrogen. In addition, increases in solution acidity cause a significant change in the track reactions that can be explained as resulting from scavenging of e aq - by H aq + to form H • . While plutonium has been shown to be an effective scavenger of precursors of molecular hydrogen below 0.1 mol dm-3 nitrate, previously reported effects of plutonium on G(H 2 ) a between 1 and 10 mol dm -3 nitric acid were not reproduced. Modelling results suggest that plutonium is unlikely to effectively compete with nitrate ions in scavenging the precursors of molecular hydrogen at higher nitric acid concentrations and this was confirmed by comparing hydrogen yields from plutonium solutions with those from americium. Finally, comparison between the radionuclide, ion accelerator experiments and model predictions leads to the conclusion that the high dose rate of accelerator studies does not significantly affect the measured hydrogen yield. These reactions provide insight into the important processes for liquors common in the reprocessing of spent nuclear fuel and the storage of highly radioactive liquid waste prior to vitrification.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2024

Impact of Drought Stress on Sorghum bicolor Yield, Deconstruction, and Microbial Conversion Determined in a Feedstocks-to-Fuels Pipeline

Sorghum is an attractive feedstock for biobased fuel and chemical production because it is familiar to farmers, naturally drought tolerant, and versatile as a food, feed, and fuel crop. Although sorghum is a promising feedstock, particularly in regions that experience drought stress, little is known about how drought conditions impact the ease of conversion of sorghum to fuels and products. This study combines agronomic field trials with a high-throughput experimental pipeline to explore the field performance and liquid biofuel (bisabolene) yields resulting from three sorghum types (photosensitive forage sorghum, optimized grain sorghum, and drought-resistant grain sorghum) grown under pre- and postflowering water limitations in two different California locations. Multiple drought treatments are compared to the control, as the timing (preflowering versus postflowering) of drought stress elicits different survival strategies and corresponding impacts on yield and composition. Forage-type sorghum maintained the highest biomass yields across all irrigation conditions and locations. Glucose and xylose yields resulting from ionic liquid pretreatment and enzymatic saccharification were not significantly impacted by irrigation treatments but differed by location and genotype. However, Rhodosporidium toruloides grown on the resulting plant hydrolysates unexpectedly produced higher titers of bisabolene for drought-stressed sorghum samples regardless of genotype.

09 BIOMASS FUELS↗
DOE OSTI2022

Auto-generating databases of Yield Strength and Grain Size using ChemDataExtractor

Abstract The emerging field of material-based data science requires information-rich databases to generate useful results which are currently sparse in the stress engineering domain. To this end, this study uses the’materials-aware’ text-mining toolkit, ChemDataExtractor, to auto-generate databases of yield-strength and grain-size values by extracting such information from the literature. The precision of the extracted data is 83.0% for yield strength and 78.8% for grain size. The automatically-extracted data were organised into four databases: a Yield Strength, Grain Size, Engineering-Ready Yield Strength and Combined database. For further validation of the databases, the Combined database was used to plot the Hall-Petch relationship for, the alloy, AZ31, and similar results to the literature were found, demonstrating how one can make use of these automatically-extracted datasets.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Crop yield response to climate change varies with crop spatial distribution pattern

The linkage between crop yield and climate variability has been confirmed in numerous studies using statistical approaches. A crucial assumption in these studies is that crop spatial distribution pattern is constant over time. Here, we explore how changes in county-level corn spatial distribution pattern modulate the response of its yields to climate change at the state level over the Contiguous United States. Our results show that corn yield response to climate change varies with crop spatial distribution pattern, with distinct impacts on the magnitude and even the direction at the state level. Corn yield is predicted to decrease by 20~40% by 2050s when considering crop spatial distribution pattern changes, which is 6~12% less than the estimates with fixed cropping pattern. The beneficial effects are mainly achieved by reducing the negative impacts of daily maximum temperature and strengthening the positive impacts of precipitation. Our results indicate that previous empirical studies could be biased in assessing climate change impacts by ignoring the changes in crop spatial distribution pattern. As a result, this has great implications for understanding the increasing debates on whether climate change will be a net gain or loss for regional agriculture.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2023

Importance of incorporating spatial and temporal variability of biomass yield and quality in bioenergy supply chain

Abstract Biofuels made from biomass and waste residues will largely contribute to United States’ 2050 decarbonization goal in the aviation sector. While cellulosic biofuels have the potential fuel performance equivalent to petroleum-based jet fuel, the biofuel industry needs to overcome the supply chain barrier caused by temporal and spatial variability of biomass yield and quality. This study highlights the importance of incorporating spatial and temporal variability during biomass supply chain planning via optimization modeling that incorporates 10 years of drought index data, a primary factor contributing to yield and quality variability. The results imply that the cost of delivering biomass to biorefinery may be significantly underestimated if the multi-year temporal and spatial variation in biomass yield and quality is not captured. For long term sustainable biorefinery operations, the industry should optimize supply chain strategy by studying the variability of yield and quality of biomass in their supply sheds.

09 BIOMASS FUELS↗
DOE OSTI2024

Estimates of lithium mass yields from produced water sourced from the Devonian-aged Marcellus Shale

Abstract Decarbonatization initiatives have rapidly increased the demand for lithium. This study uses public waste compliance reports and Monte Carlo approaches to estimate total lithium mass yields from produced water (PW) sourced from the Marcellus Shale in Pennsylvania (PA). Statewide, Marcellus Shale PW has substantial extractable lithium, however, concentrations, production volumes and extraction efficiencies vary between the northeast and southwest operating zones. Annual estimates suggest statewide lithium mass yields of approximately 1160 (95% CI 1140–1180) metric tons (mt) per year. Production decline curve analysis on PW volumes reveal cumulative volumetric disparities between the northeast (median = 2.89 X 10 7 L/10-year) and southwest (median = 5.56 × 10 7 L/10-year) regions of the state, influencing lithium yield estimates of individual wells in southwest [2.90 (95% CI 2.80–2.99) mt/10-year] and northeast [1.96 (CI 1.86–2.07) mt/10-year] PA. Moreover, Mg/Li mass ratios vary regionally, where NE PA are low Mg/Li fluids, having a median Mg/Li mass ratio of 5.39 (IQR, 2.66–7.26) and SW PA PW is higher with a median Mg/Li mass ratio of 17.8 (IQR, 14.3–20.7). These estimates indicate substantial lithium yields from Marcellus PW, though regional variability in chemistry and production may impact recovery efficiencies.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2017

Field-based high throughput phenotyping rapidly identifies genomic regions controlling yield components in rice

In order to ensure food security in the face of population growth, decreasing water and land for agriculture, and increasing climate variability, crop yields must increase faster than the current rates. Increased yields will require implementing novel approaches in genetic discovery and breeding. We demonstrate the potential of field-based high throughput phenotyping (HTP) on a large recombinant population of rice to identify genetic variation underlying important traits. We find that detecting quantitative trait loci (QTL) with HTP phenotyping is as accurate and effective as traditional labor- intensive measures of flowering time, height, biomass, grain yield, and harvest index. Furthermore, genetic mapping in this population, derived from a cross of an modern cultivar (IR64) with a landrace (Aswina), identified four alleles with negative effect on grain yield that are fixed in IR64, demonstrating the potential for HTP of large populations as a strategy for the second green revolution.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Resonance ionization of titanium: high useful yield and new autoionizing states

The isotopic composition of titanium in meteoritic phases can be used to decipher processes such as stellar nucleosynthesis and galactic chemical evolution. In order to facilitate analyses of trace amounts of titanium in atom-limited samples, here we established a new three-step resonance ionization scheme. The scheme was developed using titanium–sapphire lasers and we show that it can be easily saturated and that it yields stable isotope measurements. Using the LION (Laser Ionization Of Neutrals) instrument we demonstrate a useful yield of 10.1% ± 1.6% when ionizing from the ground state. We determined the population of two low-lying electronic states within the ground state multiplet and show that accessing all three levels of the ground state manifold would result in an overall useful yield of ~18%. The useful yield agrees well with expectations based on prior analyses of uranium using LION. In addition, we report the energy levels of nine new autoionizing states between 56 217 cm -1 and 57 086 cm -1 .

47 OTHER INSTRUMENTATION↗
DOE OSTI2019

Irradiance and temperature considerations in the design and deployment of high annual energy yield perovskite/CIGS tandems

The annual energy yields for metal halide perovskite/copper indium gallium diselenide (CIGS) tandem photovoltaics have been calculated for 16 different bandgap combinations, using both 2 terminal and 4 terminal device designs, with fixed-tilt mounting as well as 1- and 2-axis tracking. Measured complex index of refraction data were used for the materials comprising the devices, and hourly irradiance data were extracted from Version 3 of the National Solar Radiation Database. Simulations were performed for Toledo OH, Golden CO, Phoenix AZ, and New Orleans LA, and the effect of local temperature variation was also considered. The combination of irradiance and temperature variations throughout the year cause different devices to be optimal at different times of the year. Interestingly, devices constructed to maximize AM1.5 photoconversion efficiency do not necessarily maximize the annual energy yield. A detailed analysis of the monthly energy yields at the different locations reveals the interplay between the changing light and temperature conditions. Over the course of the year these effects average to some degree so that annual energy yields that are close to the maximum possible value can be achieved by several different tandem device designs. The conclusions are valid for devices made with relatively thin perovskite layers, such as those used in champion efficiency devices. When the perovskite layers are thicker, however, the device is less tolerant to variation. Our results show that close matching of bandgap pairs is not essential for the fabrication of high-performance tandems. These findings should allow manufacturing efforts to proceed without the need for precise compositional control during formation of the absorber layers.

14 SOLAR ENERGY↗
DOE OSTI2024

Influence of loblolly pine anatomical fractions and tree age on oil yield and composition during fast pyrolysis

Fast pyrolysis of woody materials is a technology pathway for producing renewable fuels and chemicals. This is a presentation of isolating needles, bark, and stemwood from a single tree as well as isolating stemwood and whole tree samples from the same species of tree with different ages and pyrolyzing each individually as well as in mixtures. This gives insight into the role of tree anatomical fractions on the resulting intermediate oil product as well as into interactions between these components. The highest carbon content oil (45.1 wt% as received) was produced from a one-to-one mixture of stemwood and needles, followed by the pure stemwood (43.4–43.8 wt% as received), while the lowest oil carbon content was from a one-to-one blend of bark and needles (26.7 wt% as received). The pyrolysis oil yield (combining oil and aqueous where separation occurred) varied from 54 wt% as received (needles) to 72.3 wt% as received (stemwood). When comparing trees of different ages, we find the change in the ratio of the anatomical fractions is a dominant factor in the product composition and yields, while the product composition and yields vary slightly with tree age when only the stemwood is pyrolyzed. Here, in this study, we present the bench-scale pyrolysis, yields, and product characterization of loblolly pine feedstocks (13- vs. 23 year-old, residues, air-classified residues, whole tree, needles, bark, and stemwood).

09 BIOMASS FUELS↗
DOE OSTI2012

Measuring the absolute deuterium-tritium neutron yield using the magnetic recoil spectrometer at OMEGA and the NIF

A magnetic recoil spectrometer (MRS) has been installed and extensively used on OMEGA and the National Ignition Facility (NIF) for measurements of the absolute neutron spectrum from inertial confinement fusion implosions. From the neutron spectrum measured with the MRS, many critical implosion parameters are determined including the primary DT neutron yield, the ion temperature, and the down-scattered neutron yield. As the MRS detection efficiency is determined from first principles, the absolute DT neutron yield is obtained without cross-calibration to other techniques. The MRS primary DT neutron measurements at OMEGA and the NIF are shown to be in excellent agreement with previously established yield diagnostics on OMEGA, and with the newly commissioned nuclear activation diagnostics on the NIF.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2012

Search for new physics in B{yields}D*{tau}nu-bar {sub {tau}} decay

B physics offers important tests of the Standard Model at low energies. Recently, BaBar observed significant deviations from the Standard Model expectations in the semileptonic B{yields}D{sup (*)}{tau}{nu}{sub {tau}} decays. Interestingly, the measured leptonic B{yields}{tau}{nu} branching fraction also deviates from CKM unitarity predictions. Motivated by these results we investigate the most general set of lowest dimensional effective operators leading to modifications of b{yields}c(u) (semi)tauonic transitions. Allowing for general flavor violation, we find that among possible operator structures, new contributions from right-right vector and right-left scalar quark currents provide viable explanations of the anomalies. In addition, we identify a number of B{yields}D*{tau}{nu}{sub {tau}} transition observables with the power to discriminate among the various effective operators' contributions. They are the differential decay rate, longitudinal D* polarization fraction, D*-{tau} opening angle asymmetry and the {tau} helicity asymmetry.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2014

Laboratory study of nitrate photolysis in Antarctic snow. I. Observed quantum yield, domain of photolysis, and secondary chemistry

Post-depositional processes alter nitrate concentration and nitrate isotopic composition in the top layers of snow at sites with low snow accumulation rates, such as Dome C, Antarctica. Available nitrate ice core records can provide input for studying past atmospheres and climate if such processes are understood. It has been shown that photolysis of nitrate in the snowpack plays a major role in nitrate loss and that the photolysis products have a significant influence on the local troposphere as well as on other species in the snow. Reported quantum yields for the main reaction spans orders of magnitude – apparently a result of whether nitrate is located at the air-ice interface or in the ice matrix – constituting the largest uncertainty in models of snowpack NO{sub x} emissions. Here, a laboratory study is presented that uses snow from Dome C and minimizes effects of desorption and recombination by flushing the snow during irradiation with UV light. A selection of UV filters allowed examination of the effects of the 200 and 305 nm absorption bands of nitrate. Nitrate concentration and photon flux were measured in the snow. The quantum yield for loss of nitrate was observed to decrease from 0.44 to 0.003 within what corresponds to days of UV exposure in Antarctica. The superposition of photolysis in two photochemical domains of nitrate in snow is proposed: one of photolabile nitrate, and one of buried nitrate. The difference lies in the ability of reaction products to escape the snow crystal, versus undergoing secondary (recombination) chemistry. Modeled NO{sub x} emissions may increase significantly above measured values due to the observed quantum yield in this study. The apparent quantum yield in the 200 nm band was found to be ∼1%, much lower than reported for aqueous chemistry. A companion paper presents an analysis of the change in isotopic composition of snowpack nitrate based on the same samples as in this study.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

High yield neutron generator based on a high-current gasdynamic electron cyclotron resonance ion source

In present paper, an approach for high yield compact D-D neutron generator based on a high current gasdynamic electron cyclotron resonance ion source is suggested. Results on dense pulsed deuteron beam production with current up to 500 mA and current density up to 750 mA/cm{sup 2} are demonstrated. Neutron yield from D{sub 2}O and TiD{sub 2} targets was measured in case of its bombardment by pulsed 300 mA D{sup +} beam with 45 keV energy. Neutron yield density at target surface of 10{sup 9} s{sup −1} cm{sup −2} was detected with a system of two {sup 3}He proportional counters. Estimations based on obtained experimental results show that neutron yield from a high quality TiD{sub 2} target bombarded by D{sup +} beam demonstrated in present work accelerated to 100 keV could reach 6 × 10{sup 10} s{sup −1} cm{sup −2}. It is discussed that compact neutron generator with such characteristics could be perspective for a number of applications like boron neutron capture therapy, security systems based on neutron scanning, and neutronography.

07 ISOTOPE AND RADIATION SOURCES↗
DOE OSTI2018

Optimization of a high-yield, low-areal-density fusion product source at the National Ignition Facility with applications in nucleosynthesis experiments

Polar-direct-drive exploding pushers are used as a high-yield, low-areal-density fusion product source at the National Ignition Facility with applications including diagnostic calibration, nuclear security, backlighting, electron-ion equilibration, and nucleosynthesis-relevant experiments. In this paper, two different paths to improving the performance of this platform are explored: (i) optimizing the laser drive, and (ii) optimizing the target. While the present study is specifically geared towards nucleosynthesis experiments, the results are generally applicable. Example data from T 2 / 3 He-gas-filled implosions with trace deuterium are used to show that yield and ion temperature (Tion) from 1.6 mm-outer-diameter thin-glass-shell capsule implosions are improved at a set laser energy by switching from a ramped to a square laser pulse shape, and that increased laser energy further improves yield and Tion, although by factors lower than predicted by 1 D simulations. Using data from D2-3He-gas-filled implosions, yield at a set Tion is experimentally verified to increase with capsule size. Uniform D-3He-proton spectra from 3 mm-outer-diameter CH shell implosions demonstrate the utility of this platform for studying charged-particle-producing reactions relevant to stellar nucleosynthesis.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2020

Neutron yield enhancement and suppression by magnetization in laser-driven cylindrical implosions

In inertial confinement fusion, an externally applied magnetic field can reduce heat losses in the compressing fuel thereby increasing neutron-averaged ion temperatures and neutron yields. Yet, magnetization is only beneficial if the magnetic pressure remains negligible compared to the fuel pressure. Experiments and three-dimensional magneto-hydrodynamic simulations of cylindrical implosions on the OMEGA laser show ion temperature and neutron yield enhancements of up to 44% and 67%, respectively. As the applied, axial magnetic field is increased to nearly 30T, both experiments and simulations show yield degradation. For magnetized, cylindrical implosions, there exists an optimal magnetic field that maximizes the increase in yield. Limiting the fuel convergence ratio by preheating the fuel can further increase the benefit of magnetization. The findings demonstrate that it is possible to create a plasma with a density of order 1 g/cm 3 and an ion temperature greater than 1 keV with a magnetic pressure comparable to the thermal pressure, a new regime for laser-produced plasmas on OMEGA.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗