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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 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

Cubic Gallium Nitride on Micropatterned Si (001) for Longer Wavelength LEDs

GaInN/GaN heterostructures of cubic phase have the potential to overcome the limitations of wurtzite structures commonly used for light emitting and laser diodes. Wurtzite GaInN suffers from large internal polarization fields, which force design compromises ( 0001 ) towards ultra-narrow quantum wells and reduce recombination volume and efficiency. Cubic GaInN microstripes grown at Rensselaer Polytechnic Institute by metal organic vapor phase epitaxy on micropatterned Si , with {111} v-grooves oriented along Si ( 001 ) , offer a system free of internal polarization fields, wider quantum wells, and smaller <00$\bar1$> bandgap energy. We prepared 6 and 9 nm Ga x In 1-x N/GaN single quantum well structures with peak wavelength ranges from 520 to 570 nm with photons predominately polarized perpendicular to the grooves. We estimate a cubic InN composition range of 0 < x < 0.5 and an upper limit of the internal quantum efficiency of 50%. Stripe geometry and polarization may be suitable for mode confinement and reduced threshold stimulated emission.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Scale-up of Next Generation Nano-Enhanced Composite Materials for Longer Lasting Consumer Goods

The objective for this project was to create an industrial-scale manufacturing operation for Vertically Aligned Carbon Nanotube Forests (VACNTs), which make up N12 Technologies’ (N12) NanoStitch® product, a prepreg additive that makes advanced composites tougher, lighter, and more durable. This was achieved using University of Dayton Research Institute’s (UDRI) 60-inch Nano Adaptive Hybrid Fabric (NAHF-X) reactor system. N12 had a unique and effective nanomaterial-based product that they were manufacturing on small-scale 1-inch wide substrate machines in Boston, MA. UDRI had a large-scale 60-inch wide nanomaterial growth reactor available for scaling up 2nd party products in Dayton, OH. Thanks to the successful cooperation between both parties, this project resulted in the world’s first industrial-scale continuous VACNT film pilot plant in Dayton, OH with an increase in VACNT supply production rate of >10X. This scale up enabled market validation via testing programs and pilot manufacturing operations with a number of customers.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Uranium Oxide Elutriation at Higher Flow Rates and Longer Times

This work supports the recovery of high-assay low-enriched uranium (i.e., U enriched in 235 U to >5% and <20%) from used nuclear fuel. One step includes elutriating triuranium octoxide (U 3 O 8 ) from a fluidized bed of alumina (Al 2 O 3 ) that fills the main reaction chamber. The experiments outlined in this report assessed the effects of the time and flow rate on the elutriation of U 3 O 8 powder from the reaction vessel. Testing at Oak Ridge National Laboratory (ORNL) was performed in a one-fourth scale experimental apparatus based on a pilot-scale system, which is the Material Recovery Pilot Plant (MRPP) at Idaho National Laboratory (INL). The experimental system comprises a supply of pressurized nitrogen (N 2 ), a gas heater, the reaction vessel, a knock-out pot, and a water trap where elutriated particles are collected for sampling. An Al 2 O 3 fluidized bed is contained within the reaction vessel. A bed of Al 2 O 3 with a nominal size of 180 µm and U 3 O 8 with a nominal size of 7 µm was fluidized at 2 different flow rates so the U 3 O 8 physically separated from the bed. The apparatus was simple and had no valves or sharp bends downstream from the reactor. The flow exited the reactor through a side port at the top. The flow passed through a knock-out vessel before the flow was passed through a bubbler to capture the U 3 O 8 . Seven tests were completed with U 3 O 8 using an elutriating gas of N 2 heated to 200°C. Tests were performed with bed loadings that comprise 25.0 g of U 3 O 8 , or 3.6 wt% of the bed mass. Except for one test performed at 12 SLPM, the gas flow rate through the bed for the other experiments was set at 10 SLPM as measured by the mass flow meter. Linear velocities through the bed were calculated as 28 and 34 cm/s, or 0.9 and 1.1 ft·s -1 . The duration of the tests ranged from 20 to 180 min, and one test had a flow cycled between 0 and 5 SLPM every 5 min for 40 min. The testing successfully demonstrated elutriation of U 3 O 8 from the fluidized bed as up to a 100% of the U 3 O 8 was transferred out of the bed. The removal of U 3 O 8 had a logarithmic dependence on flow rate. The design changes made the apparatus easier to clean, and the mass balances were better than those used in previous studies. Some elutriated Al 2 O 3 collected in the tubing that connected the reactor to the knock-out pot, but the amount of Al 2 O 3 was minimal for 10 SLPM. The flow at 12 SLPM showed considerable transport of Al 2 O 3 bed material into the reaction-vessel headspace and the transfer line to the knock-out pot.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2022

SALT3-NIR: Taking the Open-source Type Ia Supernova Model to Longer Wavelengths for Next-generation Cosmological Measurements

Abstract A large fraction of Type Ia supernova (SN Ia) observations over the next decade will be in the near-infrared (NIR), at wavelengths beyond the reach of the current standard light-curve model for SN Ia cosmology, SALT3 (∼2800–8700 Å central filter wavelength). To harness this new SN Ia sample and reduce future light-curve standardization systematic uncertainties, we train SALT3 at NIR wavelengths (SALT3-NIR) up to 2 μ m with the open-source model-training software SALTshaker , which can easily accommodate future observations. Using simulated data, we show that the training process constrains the NIR model to ∼2%–3% across the phase range (−20 to 50 days). We find that Hubble residual (HR) scatter is smaller using the NIR alone or optical+NIR compared to optical alone, by up to ∼30% depending on filter choice (95% confidence). There is significant correlation between NIR light-curve stretch measurements and luminosity, with stretch and color corrections often improving HR scatter by up to ∼20%. For SN Ia observations expected from the Roman Space Telescope, SALT3-NIR increases the amount of usable data in the SALT framework by ∼20% at redshift z ≲ 0.4 and by ∼50% at z ≲ 0.15. The SALT3-NIR model is part of the open-source SNCosmo and SNANA SN Ia cosmology packages.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2013

Making the Case For Safe Storage of Used Nuclear Fuel For Extended Periods of Time: Combining Near-Term Experiments and Analyses with Longer-Term Confirmatory Demonstrations

The need for extended storage of used nuclear fuel is increasing globally as disposition schedules for used fuel are pushed further into the future. This is creating a situation where dry storage of used fuel may need to be extended beyond normal regulatory licensing periods. While it is generally accepted that used fuel in dry storage will remain in a safe condition, there is little data that demonstrate used fuel performance in dry storage environments for long periods of time. This is especially true for high burnup used fuel.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
NASA NTRS1967

Plasma jet electrode has longer operating life

Water-cooled, silver-infiltrated tungsten electrode has twice the operating lifetime of the pure tungsten electrode used in plasma jet generators. This electrode reduces the erosion rate, ensures excellent heat transfer, and reduces thermal stresses.

Gracey, C. M.↗
NASA NTRS1972

Longer term consequences of the Short Take-Off and Landing (STOL) aircraft system

An assessment of the STOL aircraft and the various means of employing it are discussed in the light of a research study to evaluate the efficacy of such analyses. It was determined that current approaches to assessment are generally inadequate for investigating the full social consequences of implementing a new technology. It is stated that a meaningful methodology of technology assessment must reflect mechanisms underlying the relationship of technology to social change. Interrelated methods which are discussed are: (1) gaming and simulation as heurisitic approaches in analysis and inquiry, (2) long range planning and questions of the future, (3) planning theory as a background for critical analysis of policy planning, and (4) social theory, with particular emphasis on social change and systems theories.

Laporte, T. R.↗
NASA NTRS1980

Longer shelf life for ceramic slurries

Viscosity of ceramic-coating slurries containing organic acrylate viscosity-control agent is stabilized for over 2 months by addition of ammonium hydroxide without significant changes.

Izu, Y. D.↗
NASA NTRS1983

The solar O III spectrum. II - Longer wavelengths, line widths, and the He II Lyman alpha radiation field

The solar O III spectrum above 900 A is analyzed, including several visible and infrared lines which are important in nebular studies. The dependence of the line intensities on the rate of photoexcitation by He Ly-alpha is determined, and the observability of these lines in the solar spectrum is studied. The impact approximation is employed to calculate the expected line widths of the stronger solar O III lines. The photoexciting field at 304 A calculated from the observed intensities of the O III lines below 900 A (Bhatia et al., 1982) is compared with the field predicted by a recent model (Avrett et al., 1976). It is shown that additional radiation trapping must be present beyond that given by this model.

Kastner, S. O.↗
NASA NTRS1987

'But Captain, I've been doing this a lot longer than you have' - The effects of 'role-reversal' on crew interaction

Legislation providing for airline deregulation has, among other things, created some ambiguity with respect to cockpit role structures. With the demise of some airlines, the absorption of others, the merging of seniority lists, and a new shortage of pilots, individuals with experience equivalent to or greater than that of the pilot in command may be placed in roles of lesser status. A formerly senior captain may be flying in the right seat as a first officer with an individual very much 'junior' in terms of both age and experience. Moreover, the mandatory retirement of airline pilots at age 60 does not apply to flight engineers, and some are 'down-grading' to fly in that capacity. The effects of this 'role-reversal' phenomenon on the crew coordination process have not been explored. The purpose of this study was to begin investigating this phenomenon using data obtained from a previous 'short-haul' full mission study conducted by Foushee, Lauber, Baetge, and Acomb (1986).

Lozito, Sandra C.↗
NASA NTRS1992

Capacitive Proximity Sensor Has Longer Range

Capacitive proximity sensor on robot arm detects nearby object via capacitive effect of object on frequency of oscillator. Sensing element part of oscillator circuit operating at about 20 kHz. Total capacitance between sensing element and ground constitutes tuning capacitance of oscillator. Sensor circuit includes shield driven by replica of alternating voltage applied to sensing element. Driven shield concentrates sensing electrostatic field in exterior region to enhance sensitivity to object. Sensitivity and dynamic range has corresponding 12-to-1 improvement.

Vranish, John M.↗
NASA NTRS1994

An overview of millimeter-wave spectroscopic measurements of chlorine monoxide at Thule, Greenland, February-March, 1992: Vertical profiles, diurnal variation, and longer-term trends

Measurements of chlorine monoxide in the stratosphere over Thule, Greenland (73.6 N, 68.4 W) were made quasi-continuously during the period February 8 to March 24, 1992, using a high-sensitivity ground based mm-wave spectrometer. These observations give diurnal, short term, and long term changes in the mixing ratio and vertical distribution of ClO. At an equivalent time after the Antarctic winter solstice, very large concentrations (up to approximately 1.5 ppbv) occur in lower stratospheric ClO, resulting in massive ozone destruction. We saw no evidence for large (approximately 1 top 1.5 ppbv) amounts of ClO in the 16-25 km range over Thule in February or March, in agreement with UARS (satellite) observations by the MLS mm-wave spectrometer for this period, and in marked contrast to UARS/MLS and ER-2 aircraft measurements over northern Europe and eastern Canada, respectively, during January, 1992. We have evidence for smaller enhancements (approximately 0.2 to 0.5 ppbv) in the 18-30 km range during late February-early March, which could result from transport of residual low NO2 air following earlier polar stratospheric cloud (PSC) processing (the last of which occurred at least one month earlier, however) or the result of chemical processing by Pinatubo aerosols. Direct influence of Pinatubo aerosols on Arctic ozone during the spring of 1992 has been difficult to assess, and this enhancement of low-altitude ClO might be a significant indicator of aerosol effects.

De Zafra, R. L.↗