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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 487 records · Page 27
All sourcesNASA NTRSDOE OSTI
NASA NTRS1979

Contour measurement system

A measurement system for measuring the departures from a straight line of discrete track sections of a track along a coal face in a mine employing a vehicle having a pair of spaced wheel assemblies which align with the track is presented. A reference arm pivotally connects between the wheel assemblies, and there is indicating means for measuring the angle of pivot between the arm and each of the wheel assemblies. The length of the device is less than the length of a track section, and thus when one of the wheel assemblies is on one track section and one is on an adjoining track section, the sum of the indicated angles will be indicative of the angle between track sections. Thus, from the length of a track section and angle, the departure of each track section from the line may be calculated.

Currie, J. R.↗
NASA NTRS1988

Linear force device

The object of the invention is to provide a mechanical force actuator which is lightweight and manipulatable and utilizes linear motion for push or pull forces while maintaining a constant overall length. The mechanical force producing mechanism comprises a linear actuator mechanism and a linear motion shaft mounted parallel to one another. The linear motion shaft is connected to a stationary or fixed housing and to a movable housing where the movable housing is mechanically actuated through actuator mechanism by either manual means or motor means. The housings are adapted to releasably receive a variety of jaw or pulling elements adapted for clamping or prying action. The stationary housing is adapted to be pivotally mounted to permit an angular position of the housing to allow the tool to adapt to skewed interfaces. The actuator mechanisms is operated by a gear train to obtain linear motion of the actuator mechanism.

Clancy, John P.↗
DOE OSTI2013

Micro-cone targets for producing high energy and low divergence particle beams

The present invention relates to micro-cone targets for producing high energy and low divergence particle beams. In one embodiment, the micro-cone target includes a substantially cone-shaped body including an outer surface, an inner surface, a generally flat and round, open-ended base, and a tip defining an apex. The cone-shaped body tapers along its length from the generally flat and round, open-ended base to the tip defining the apex. In addition, the outer surface and the inner surface connect the base to the tip, and the tip curves inwardly to define an outer surface that is concave, which is bounded by a rim formed at a juncture where the outer surface meets the tip.

47 OTHER INSTRUMENTATION↗
DOE OSTI2018

Removably attachable snubber assembly

A removably attachable snubber assembly for turbine blades includes a turbine blade airfoil including a trailing edge and a leading edge joined by a pressure side and a suction side to provide an outer surface extending in a radial direction to a tip. At least one snubber attachment platform is integrally formed onto the outer surface of the turbine blade airfoil. The at least one snubber attachment platform includes an interlocking mechanism. A snubber is removably attachable to the at least one snubber attachment platform, the snubber including a first end, a second end, a trailing edge, a leading edge, a snubber length, and a snubber width. The snubber also includes a removable attachment mechanism on at least one of the first end and the second end that connects with the interlocking mechanism on the at least one snubber attachment platform.

42 ENGINEERING↗
DOE OSTI2015

Morphology of blazar-induced gamma ray halos due to a helical intergalactic magnetic field

We study the characteristic size and shape of idealized blazar-induced cascade halos in the 1–100,GeV energy range assuming various non-helical and helical configurations for the intergalactic magnetic field (IGMF). While the magnetic field creates an extended halo, the helicity provides the halo with a twist. Under simplifying assumptions, we assess the parameter regimes for which it is possible to measure the size and shape of the halo from a single source and then to deduce properties of the IGMF. We find that blazar halo measurements with an experiment similar to Fermi-LAT are best suited to probe a helical magnetic field with strength and coherence length today in the ranges 10{sup −17} ∼< B{sub 0} / Gauss ∼< 10{sup −13} and 10 Mpc ∼< λ ∼< 10 Gpc where H ∼ B{sub 0}{sup 2} / λ is the magnetic helicity density. Stronger magnetic fields or smaller coherence scales can still potentially be investigated, but the connection between the halo morphology and the magnetic field properties is more involved. Weaker magnetic fields or longer coherence scales require high photon statistics or superior angular resolution.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2014

Microscopic Theory of the Long-Time Diffusivity and Intermediate-Time Anomalous Transport of a Nanoparticle in Polymer Melts

The transport of a single nanoparticle in unentangled and entangled polymer melts is studied based on a microscopic, force-level, self-consistent generalized Langevin equation approach. Nanoparticle self-motion and length-scale-dependent polymer relaxation enter as two parallel and competing channels of force relaxation. For entangled melts, particle long-time mobility exhibits size-dependent non-Stokes–Einstein behaviors controlled by (i) fast diffusion and length-scale-dependent collective relaxation of the unentangled matrix for particles smaller than the tube diameter and (ii) polymer relaxation via reptation for nanoparticles larger than the tube diameter. The two regimes are connected by a relatively sharp but continuous crossover. Recovery of hydrodynamic behavior requires the nanoparticle to be roughly 10 times larger than the tube diameter. Theoretical predictions for the diffusion constant are in good agreement with recent simulations of unentangled and lightly entangled melts, including the crossover regime where the nanoparticle and tube diameters are roughly equal. The calculations are also in reasonable accord with several experiments in entangled synthetic polymer melts and DNA solutions, although the activated hopping motion not included in the present theory may be important in a narrow intermediate crossover regime for sufficiently entangled polymers. The predictions of the theory for intermediate-time anomalous diffusion are of mixed quality based on comparison to simulations. Furthermore, the significant limitations identified are associated with our minimalist treatment of collective density fluctuation relaxation on intermediate time and length scales, including the possible importance of non-reptation relaxation processes in entangled melts.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2024

Medium-Range Structural Order as the Driver of Activated Dynamics and Complexity Reduction in Glass-Forming Liquids

Here, we analyze in depth the Elastically Collective Nonlinear Langevin Equation theory of activated dynamics in metastable liquids to establish that the predicted inter-relationships between the alpha relaxation time, local cage and collective elastic barriers, dynamic localization length, and shear modulus are causally related within the theory to the medium range order (MRO) static correlation length. The latter grows exponentially with density for metastable hard sphere fluids and as a nonuniversal inverse power law with temperature for supercooled liquids under isobaric conditions. The physical origin of predicted connections between the alpha time and other metrics of cage order and the thermodynamic inverse dimensionless compressibility is fully established. It is discovered that although kinetic constraints from the real space first coordination shell are important for the alpha time, they are of secondary importance compared to the consequences of the more universal MRO correlations in both the modestly and deeply metastable regimes. This understanding sheds new light on the theoretical basis for, and prior successes of, the predictive mapping of chemically complex thermal liquids to effective hard sphere fluids based on matching their dimensionless compressibilities, a scheme we call “complexity reduction”. In essence, the latter is equivalent to the physical requirement that the thermal liquid MRO correlation equals that of its effective hard sphere analog. The mapping alone is shown to provide a remarkable level of quantitative predictive power for the glass transition temperature T g of 21 molecular and polymer liquids. Predictions for the chemically specific absolute magnitude and growth with cooling of the MRO correlation length are obtained and lie in the window of 2–6 nm at T g . Dynamic heterogeneity, elastic facilitation, and beyond pair structure issues are briefly discussed. Future opportunities to theoretically analyze the equilibrated deep glass regime are outlined.

cancer↗
DOE OSTI2014

Accessing (Ba 1-x Sr x )Al 2 Si 2 O 8 :Eu Phosphors for Solid State White Lighting via Microwave-assisted Preparation: Tuning Emission Color by Coordination Environment

The preparation of Eu 2+ -substituted barium aluminum silicates is achieved using a rapid microwave-assisted preparation. The phase evolution of two BaAl 2 Si 2 O 8 :Eu 2+ polymorphs, the higher temperature hexagonal phase (hexacelsian), and the lower temperature monoclinic phase (celsian), is explored by varying the ramp time and soak time. This preparation method significantly reduces the reaction time needed to form these phases compared to conventional solid state routes. The luminescent properties of the two phases are identified under UV excitation with the hexagonal phase emitting in the UV region (λ em = 372 nm) and the monoclinic phase emitting in the blue region (λ em = 438 nm). The differences in optical properties of the two polymorphs are correlated to the coordination number and arrangement of the alkali earth site. The optical properties of the monoclinic phase can be further tuned through the substitution of Sr 2+ , forming the solid solution (Ba 1–x Sr x )Al 2 Si 2 O 8 :Eu 2+ . Changes in the crystal structure due to Sr 2+ substitution produce a surprising blue-shift in the emission spectrum, which is explained by a greater dispersion of bond lengths in the (Ba/Sr)–O polyhedra. The entire monoclinic solid solution exhibits excellent quantum yields of nearly 90 %, owing to the structural rigidity provided by the highly connected tetrahedral network.

Brgoch, Jakoah↗
DOE OSTI2020

Robust late twenty-first century shift in the regional monsoons in RegCM-CORDEX simulations

Abstract We use an unprecedented ensemble of regional climate model (RCM) projections over seven regional CORDEX domains to provide, for the first time, an RCM-based global view of monsoon changes at various levels of increased greenhouse gas (GHG) forcing. All regional simulations are conducted using RegCM4 at a 25 km horizontal grid spacing using lateral and lower boundary forcing from three General Circulation Models (GCMs), which are part of the fifth phase of the Coupled Model Inter-comparison Project (CMIP5). Each simulation covers the period from 1970 through 2100 under two Representative Concentration Pathways (RCP2.6 and RCP8.5). Regional climate simulations exhibit high fidelity in capturing key characteristics of precipitation and atmospheric dynamics across monsoon regions in the historical period. In the future period, regional monsoons exhibit a spatially robust delay in the monsoon onset, an increase in seasonality, and a reduction in the rainy season length at higher levels of radiative forcing. All regions with substantial delays in the monsoon onset exhibit a decrease in pre-monsoon precipitation, indicating a strong connection between pre-monsoon drying and a shift in the monsoon onset. The weakening of latent heat driven atmospheric warming during the pre-monsoon period delays the overturning of atmospheric subsidence in the monsoon regions, which defers their transitioning into deep convective states. Monsoon changes under the RCP2.6 scenario are mostly within the baseline variability.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2018

Unique Determination of 3-Connected Plane Domains by Relative Conformal Moduli of Pairs of Boundary Components

We study the boundary values of conformal mappings of plane finitely connected domains. We present a complete exposition of a theorem giving an exhaustive description of the boundary values of such mappings in terms of conformal moduli (extremal lengths) of pairs of boundary components of a domain of connectedness at most 3. Bibliography: 12 titles.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2021

Synchrotron X-ray microtomography and multifractal analysis for the characterization of pore structure and distribution in softwood pellet biochar

Biochar pores in the micrometer range (1–100 µm) derive from cellular structures of the plant biomass subjected to pyrolysis or can be the result of mechanical processing, such as pelleting. In this study, synchrotron X-ray microtomography was used to investigate the internal pore structure of softwood pellet biochar produced by slow pyrolysis at 550 and 700 °C. The microtomographic data sets consisted of 2025 images of 2560 × 2560 voxels with a voxel side length of 0.87 µm. The three-dimensional reconstructions revealed that pelleting and pyrolysis significantly altered the pore structures of the wood feedstock, creating a network of connected pores between fragments that resembled the wood morphology. While higher pyrolysis temperature increased the specific surface area (as determined by BET nitrogen adsorption), it did not affect the total observed porosity. Multifractal analysis was applied to assess the characteristics of the frequency distribution of pores along each of the three dimensions of reconstructed images of five softwood pellet biochar samples. The resulting singularity and Rényi spectra (generalized dimensions) indicated that the distribution of porosity had monofractal scaling behavior, was homogeneous within the analyzed volumes and consistent between replicate samples. Moreover, the pore distributions were isotropic (direction-independent), which is in strong contrast with the anisotropic pore structure of wood. As pores at the scale analyzed in this study are relevant, for example, for the supply of plant accessible water and habitable space for microorganisms, our findings combined with the ability to reproduce biochar with such pore distribution offer substantial advantages in various biochar applications.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2019

Thermodynamically Controlled Linker Installation in Flexible Zirconium Metal–Organic Frameworks

A series of metal–organic frameworks (MOFs) (PCN-606-OH-TPDC, PCN-606-OMe-TPDC, PCN-606-OH-EDDB, and PCN-606-OMe-EDDB) are synthesized through linker installation onto open sites of 8-connected Zr6 clusters in PCN-606-R (where R =-OH or -OMe) parent frameworks of differing flexibilities. The two postsynthetically installed linear linkers possess slight differences in length and bulk, which result in a noticeable difference in the installation temperatures, reflective of a different thermodynamic barrier to incorporation into PCN-606-R. The X-ray crystallographic data as well as the N2 adsorption properties of these four newly produced MOFs are explored and compared to gain a more comprehensive understanding of the implications that this difference in linker size and bulk have during insertion into flexible MOFs.

membrane, carbon capture, materials and chemistry ↗
DOE OSTI2020

Global analysis of SBP gene family in Brachypodium distachyon reveals its association with spike development

SQUAMOSA-promoter binding like proteins (SBPs/SPLs) are plant specific transcription factors targeted by miR156 and involved in various biological pathways, playing multi-faceted developmental roles. This gene family is not well characterized in Brachypodium. We identified a total of 18 SBP genes in B. distachyon genome. Phylogenetic analysis revealed that SBP gene family in Brachypodium expanded through large scale duplication. A total of 10 BdSBP genes were identified as targets of miR156. Transcript cleavage analysis of selected BdSBPs by miR156 confirmed their antagonistic connection. Alternative splicing was observed playing an important role in BdSBPs and miR156 interaction. Characterization of T-DNA Bdsbp9 mutant showed reduced plant growth and spike length, reflecting its involvement in the spike development. Expression of a majority of BdSBPs elevated during spikelet initiation. Specifically, BdSBP1 and BdSBP3 differentially expressed in response to vernalization. Differential transcript abundance of BdSBP1, BdSBP3, BdSBP8, BdSBP9, BdSBP14, BdSBP18 and BdSBP23 genes was observed during the spike development under high temperature. Co-expression network, protein–protein interaction and biological pathway analysis indicate that BdSBP genes mainly regulate transcription, hormone, RNA and transport pathways. Our work reveals the multi-layered control of SBP genes and demonstrates their association with spike development and temperature sensitivity in Brachypodium.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2020

FeederGAN: Synthetic Feeder Generation via Deep Graph Adversarial Nets

This paper presents a novel, automated, generative adversarial networks (GAN) based synthetic feeder generation mechanism, abbreviated as FeederGAN. FeederGAN digests real feeder models represented by directed graphs via a deep learning framework powered by GAN and graph convolutional networks (GCN). Information of a distribution feeder circuit is extracted from its model input files so that the device connectivity is mapped onto the adjacency matrix and the device characteristics, such as circuit types (i.e., 3-phase, 2-phase, and 1-phase) and component attributes (e.g., length and current ratings), are mapped onto the attribute matrix. Then, Wasserstein distance is used to optimize the GAN and GCN is used to discriminate the generated graphs from the actual ones. A greedy method based on graph theory is developed to reconstruct the feeder using the generated adjacency and attribute matrices. Furthermore, our results show that the GAN generated feeders resemble the actual feeder in both topology and attributes verified by visual inspection and by empirical statistics obtained from actual distribution feeders.

42 ENGINEERING↗
NASA NTRS1993

Polyimide based amorphous silicon solar modules

Requirements for space power are increasingly emphasizing lower costs and higher specific powers. This results from new fiscal constraints, higher power requirements for larger applications, and the evolution toward longer distance missions such as a Lunar or Mars base. The polyimide based a-Si modules described are being developed to meet these needs. The modules consist of tandem a-Si solar cell material deposited directly on a roll of polyimide. A laser scribing/printing process subdivides the deposition into discrete cell strips which are series connected to produce the required voltage without cutting the polymer backing. The result is a large, monolithic, blanket type module approximately 30 cm wide and variable in length depending on demand. Current production modules have a specific power slightly over 500 W/Kg with room for significant improvement. Costs for the full blanket modules range from $30/Watt to $150/Watt depending on quantity and engineering requirements. Work to date focused on the modules themselves and adjusting them for the AMO spectrum. Work is needed yet to insure that the modules are suitable for the space environment.

Jeffrey, Frank R.↗
NASA NTRSDate not supplied

Going With the Flow: Using a Particle Dispersion Model to Reveal Links Between Ocean Ecosystems and Marine Aerosols

Marine biogenic particle contributions to atmospheric aerosol concentrations are not well understood though they are important for determining cloud optical and cloud nucleating properties. Here we examine the relationship between marine aerosol measurements with satellite and model fields of ocean biology and meteorological variables during the North Atlantic Aerosols and Marine Ecosystems Study (NAAMES). NAAMES consisted of four field campaigns between November 2015 and April 2018 that aligned with the four major phases of the annual phytoplankton bloom cycle. The FLEXPART Lagrangian particle dispersion model is used to connect these variables spatiotemporally to ship-based aerosol. We find that correlations between some aerosol measurements with satellite measured and modelled variables increase with increasing trajectory length. This indicates biological and meteorological processes over the air mass history are influential to measured particle properties. For example, results show organic aerosol mass is driven by biogenic volatile organic compound (VOC) emissions from photosynthesis by phytoplankton stocks during advection into the region. In contrast, primary marine aerosol (PMA) concentrations showed better correlations to variables weighted with shorter air mass residence times, which reflects their localized origin as primary emissions. Evidence also suggest variability in PMA concentrations likely play an important role in VOC emission removal. The removal of VOCs lessen their impact on particle number and mass concentrations. The sensitivity of marine aerosols to the main ecosystem-atmosphere drivers and its dependence on air mass history are to be further discussed.

Kevin J Sanchez↗
DOE OSTI2019

Gating grid driver for gas radiation detectors

A gating grid driver for use with radiation detectors, such as time projection chambers and other similar devices that require a gating grid that operates in a bipolar mode with different electrostatic potentials on alternating wires. To open such gating grids, the driver shorts the alternate wires to a common voltage Va. Later, this driver closes the grid by restoring the voltage differences in the adjacent wires. By connecting the driver circuit to the gating grid via low impedance transmission lines, the driver circuit opens the gating grid in 0.35 μs, minimizing the lost drift length associated with this opening time. The circuit consists of 2 pairs of N- and P-MOSFET switches and includes two adjustable capacitors and resistors that can be used to adjust the opening time, and shift the balance of positive and negative charge for individual radiation detector.

Tangwancharoen, Suwat↗
DOE OSTI2017

Long-term Optical Polarization Variability and Multiwavelength Analysis of Blazar Mrk 421

The results of 8 yr R-band photopolarimetric data of blazar Mrk 421 collected from 2008 February to 2016 May are presented, along with extensive multiwavelength observations covering radio to TeV γ-rays around the flares observed in 2008 May, 2010 March, and 2013 April. The most important results are found in 2013, when the source displayed in the R band a very high brightness state of 11.29 ± 0.03 mag (93.60 ± 1.53 mJy) on April 10 and a polarization degree of 11.00% ± 0.44% on May 13. The analysis of the optical data shows that the polarization variability is due to the superposition of two polarized components that might be produced in two distinct emitting regions. An intranight photopolarimetric variability study carried out over seven nights after the 2013 April maximum found flux and polarization variations on the nights of April 14, 15, 16, and 19. In addition, the flux shows a minimum variability timescale of Δt = 2.34 ± 0.12 hr, and the polarization degree presents variations of ∼1%–2% on a timescale of Δ t ∼ minutes. Also, a detailed analysis of the intranight data shows a coherence length of the large-scale magnetic field of l{sub B}≃0.3 pc, which is the same order of magnitude as the distance traveled by the relativistic shocks. This result suggests that there is a connection between the intranight polarimetric variations and spatial changes of the magnetic field. Analysis of the complete R-band data along with the historical optical light curve found for this object shows that Mrk 421 varies with a period of 16.26 ± 1.78 yr.

79 ASTRONOMY AND ASTROPHYSICS↗