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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 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
NASA NTRS1986

Programable Pipelined-Image Processor

Computer serves as pipelined processor for imagery or other two-dimensional digital data. Processor does feature extraction, smoothing, edge detection, texture measurement, and stereoscoptic area correlation. Also plans routes for obstacle avoidance by robots and solves two-dimensional partial differential equations. Image processor consists of modular units: each includes set of computing elements of types particularly useful in pipelined-image processing. Flexible interconnection scheme used to route data to subsequent stages of pipeline.

Gennery, D. B.↗
DOE OSTI2013

Enhancing the Chemical Mixture Methodology in Emergency Preparedness and Consequence Assessment

Emergency preparedness personnel at US Department of Energy (DOE) facilities use the chemical mixture methodology (CMM) to estimate the potential health impacts to workers and the public from the unintended airborne release of chemical mixtures. The CMM uses a Hazard Index (HI) to compare a chemical’s concentration at a receptor location to an appropriate concentration limit for that chemical. This limit is typically based on Protection Action Criteria (PAC) values developed and published by the DOE. As a first cut, the CMM sums the HIs for all the chemicals in a mixture to conservatively estimate their combined health impact. A cumulative HI ≥ 1.0 represents a concentration at or exceeding the concentration limit and indicates the potential for adverse health effects. Next, health code numbers (HCNs) are used to identify the target organ sets that may be impacted by exposure to each chemical in a mixture. The sum of the HIs for the maximally impacted target organ set is used to provide a refined, though still conservative estimate, of the potential for adverse health effects from exposure to the chemical mixture. This paper explores approaches to further enhance the effectiveness of the CMM by using HCN weighting factors to reduce over-conservatism. A series of 24 case studies have been defined to evaluate both the existing CMM and three new approaches for improving the CMM. The first approach uses a set of HCN weighting factors that are applied based on the priority ranking of the HCNs for each chemical. The second approach uses weighting factors based on the priority rankings of the HCNs established for a given type of concentration limit. The third approach uses information on the exposure route used to derive PAC values and the second approach’s HCN ranking to derive and apply its HCN weighting factors. Initial testing indicates that applying weighting factors reduces the over-conservatism in the CMM for certain types of chemical mixtures, though care must be taken to avoid introducing non-conservative results. In the near future, additional testing and analysis will be conducted that will lead to the adoption of one of the tested approaches into the CMM. The long-term goal is to develop and implement a more comprehensive approach that will take into account the specific health effects that were observed during the studies used to derive the chemical-specific concentration limits used in the CMM.

acute health effects↗
DOE OSTI2018

Common traffic routes for imported spermine and endosomal glypican-1-derived heparan sulfate in fibroblasts

Import of the polyamine spermine from the extracellular environment depends on the presence of cell surface heparan sulfate proteoglycans, such as glypican-1. This proteoglycan is internalized by endocytosis, releases its heparan sulfate chains in endosomes by a nitric oxide-, copper- and amyloid precursor protein-dependent mechanism, then penetrates the membrane and is transported to the nucleus and then to autophagosomes. This process is spontaneous or induced by ascorbate depending on the growth-state of the cell. Here, we have explored possible connections between the heparan sulfate traffic route and spermine uptake and delivery in wild-type and Tg2576 mouse fibroblasts. Cells were examined by deconvolution immunofluorescence microscopy. The antibodies used were specific for spermine, glypican-1-derived heparan sulfate, Rab7, nucleolin and a marker for autophagosomes. Endogenous immunostainable spermine was primarily associated with autophagosomes. When spermine synthesis was inhibited, imported spermine appeared in Rab7-positive endosomes. When ascorbate was added, heparan sulfate and spermine were transported to the nucleus where they colocalized with nucleolin. Spermine also appeared in autophagosomes. In a pulse-chase experiment, heparan sulfate and spermine were first arrested in late endosomes by actinomycin D treatment. During the chase, when arrest was abolished, heparan sulfate and spermine were both transported to the nucleus and targeted nucleolin. In amyloid precursor protein{sup -/-}-fibroblasts, ascorbate failed to induce release of heparan sulfate and spermine remained in the endosomes. We propose that cell surface glypican-1 carries spermine to the endosomes and that the released heparan sulfate carries spermine across the membrane into the cytosol and then to the nucleus.

60 APPLIED LIFE SCIENCES↗
NASA NTRS1996

Global Interconnectivity Between Mobile Satellite and Terrestrial Users: Call Signalling Issues and Challenges

This paper will discuss some of the challenges in connecting mobile satellite users and mobile terrestrial users in a cost efficient manner and with a grade of service comparable to that of satellite to fixed user calls. Issues arising from the translation between the mobility management protocols resident at the satellite Earth station and those resident at cellular switches - either GSM (Group Special Mobile) or IS-41 (used by U.S. digital cellular systems) type - will be discussed. The impact of GSM call routing procedures on the call setup of a satellite to roaming GSM user will be described. Challenges facing provision of seamless call handoff between satellite and cellular systems will be given. A summary of the issues explored in the paper are listed and future work outlined.

mobile satellite usersGroup Special MobileGSMdigit↗
NASA NTRS2017

Recommended Changes to Interval Management to Achieve Operational Implementation

A 19-day flight test of an Interval Management (IM) avionics prototype was conducted in Washington State using three aircraft to precisely achieve and maintain a spacing interval behind the preceding aircraft. NASA contracted with Boeing, Honeywell, and United Airlines to build this prototype, and then worked closely with them, the FAA, and other industry partners to test this prototype in flight. Four different IM operation types were investigated during this test in the en route, arrival, and final approach phases of flight. Many of the IM operations met or exceeded the design goals established prior to the test. However, there were issues discovered throughout the flight test, including the rate and magnitude of IM commanded speed changes and the difference between expected and actual aircraft deceleration rates.

Baxley, Brian↗
NASA NTRSDate not supplied

Low-Temperature Formation of Carbonaceous Grains from PAHs

Astronomical observations have detected interstellar carbon in the form of polycyclic aromatic hydrocarbons(PAHs) as well as carbonaceous dust, confirming its presence in both gaseous and solid phases. The goal of this study is to experimentally investigate low-temperature chemical pathways between these two phases in order to better understand the evolution of cosmic carbon. Cosmic dust analogs are produced in the supersonic expansion of an argon jet seeded with aromatic molecules: benzene, naphthalene, anthracene, phenanthrene, and pyrene. These are prototype aromatic molecules of compact and non compact structure, and are used to evaluate the effect of precursor structure on the molecular complexity of the resulting grains. The seeded jet is exposed to an electrical discharge and the carbonaceous grains are collected and probed ex situ via laser desorption mass spectrometry. Mass spectra reveal a rich molecular diversity within the grains, including fragments of the parent molecule but also growth into larger complex organic molecules (COMs). In all experiments, the largest number of products is found in the m/z range 200-250, and C16H10 (attributed to pyrene and/or its isomers) is found to be a dominant product, pointing at the formation of this stable PAH as a preferential route in the growth to larger PAHs. Comparison to mass spectra from the Murchison meteorite reveals a similar dominance of compounds related toC16H10 at m/z = 202. Evidence of the methyl addition-cyclization mechanism in the anthracene experiment is reported. PAH structure is found to impact the dust production yield, as seen by the greater yield for the anthracene compared to the phenanthrene experiment. PAH growth at low temperatures via barrierless routes involving the addition of alkyl- and phenyl-type radicals is suggested as a viable pathway to COMs. These results suggest that PAH growth and dust formation from PAHs are feasible at low temperatures in photon-dominated regions and circumstellar envelopes.

L Gavilan↗
DOE OSTI2017

Sol-gel precursors and products thereof

The present invention provides a generalizable single-source sol-gel precursor capable of introducing a wide range of functionalities to metal oxides such as silica. The sol-gel precursor facilitates a one-molecule, one-step approach to the synthesis of metal-silica hybrids with combinations of biological, catalytic, magnetic, and optical functionalities. The single-source precursor also provides a flexible route for simultaneously incorporating functional species of many different types. The ligands employed for functionalizing the metal oxides are derived from a library of amino acids, hydroxy acids, or peptides and a silicon alkoxide, allowing many biological functionalities to be built into silica hybrids. The ligands can coordinate with a wide range of metals via a carboxylic acid, thereby allowing direct incorporation of inorganic functionalities from across the periodic table. Using the single-source precursor a wide range of functionalized nanostructures such as monolith structures, mesostructures, multiple metal gradient mesostructures and Stober-type nanoparticles can be synthesized. ##STR00001##

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Charging Needs for Battery Electric Semi Trucks

Battery-electric vehicles provide a pathway to decarbonize heavy-duty trucking, but the market for electric trucks is nascent, and specific charging requirements remain uncertain. This paper summarizes methods and findings from Charging Needs for Electric Semi-Trailer Trucks [1] wherein we leverage large-scale vehicle telematics data (>205 million miles of driving) to estimate the charging behaviors and infrastructure requirements for U.S. battery-electric semi-trailer trucks within three operating segments: local, regional, and long-haul. We model two types of charging - mid-shift (fast en-route charging) and off-shift (slow depot charging) - and show that off-shift charging at speeds compatible with current light-duty charging infrastructure (i.e., =350 kW) can supply 35% to 77% of total energy demand for local and regional trucks with =300-mile range. Megawatt-level speeds are required for mid-shift charging, which make up 44% to 57% of energy demand for long-haul trucks with =500-mile range. However, the role of off-shift charging increases as the range for battery-electric trucks increases and when off-shift charging is widely available.

ADVANCED PROPULSION SYSTEMS↗
DOE OSTI2015

Creating orbiting vorticity vectors in magnetic particle suspensions through field symmetry transitions–a route to multi-axis mixing

It has recently been reported that two types of triaxial electric or magnetic fields can drive vorticity in dielectric or magnetic particle suspensions, respectively. The first type-symmetry -- breaking rational fields -- consists of three mutually orthogonal fields, two alternating and one dc, and the second type -- rational triads -- consists of three mutually orthogonal alternating fields. In each case it can be shown through experiment and theory that the fluid vorticity vector is parallel to one of the three field components. For any given set of field frequencies this axis is invariant, but the sign and magnitude of the vorticity (at constant field strength) can be controlled by the phase angles of the alternating components and, at least for some symmetry-breaking rational fields, the direction of the dc field. In short, the locus of possible vorticity vectors is a 1-d set that is symmetric about zero and is along a field direction. In this paper we show that continuous, 3-d control of the vorticity vector is possible by progressively transitioning the field symmetry by applying a dc bias along one of the principal axes. Such biased rational triads are a combination of symmetry-breaking rational fields and rational triads. A surprising aspect of these transitions is that the locus of possible vorticity vectors for any given field bias is extremely complex, encompassing all three spatial dimensions. As a result, the evolution of a vorticity vector as the dc bias is increased is complex, with large components occurring along unexpected directions. More remarkable are the elaborate vorticity vector orbits that occur when one or more of the field frequencies are detuned. As a result, these orbits provide the basis for highly effective mixing strategies wherein the vorticity axis periodically explores a range of orientations and magnitudes.

36 MATERIALS SCIENCE↗
DOE OSTI2019

String Method for Protein–Protein Binding Free-Energy Calculations

A powerful computational strategy to determine the equilibrium association constant of two macromolecules with explicit-solvent molecular dynamics (MD) simulations is the "geometric route", which considers the reversible physical separation of the bound complex in solution. Nonetheless, multiple challenges remain to render this type of methodology reliable and computationally efficient in practice. In particular, in one, formulation of the geometric route relies on the potential of mean force (PMF) for physically separating the two binding partners restrained along a straight axis, which must be selected prior to the calculation. However, practical applications indicate that the calculation of the separation PMF along the predefined rectilinear pathway may be suboptimal and slowly convergent. Recognizing that a rectilinear straight separation pathway is generally not representative of how the protein complex physically separates in solution, we put forth a novel theoretical framework for binding free-energy calculations, leaning on the optimal curvilinear minimum free-energy path (MFEP) determined from the string method. The proposed formalism is validated by comparing the results obtained using both rectilinear and curvilinear pathways for a prototypical host-guest complex formed by cucurbit[7]uril (CB[7]) binding benzene, and for the barnase-barstar protein complex. On the basis of multi-microsecond MD calculations, we find that the calculations following the traditional rectilinear pathway and the string-based curvilinear pathway agree quantitatively, but convergence is faster with the latter.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1991

Evidence of chaotic pattern in solar flux through a reproducible sequence of period-doubling-type bifurcations

A preliminary study of the limits to solar flux intensity prediction, and of whether the general lack of predictability in the solar flux arises from the nonlinear chaotic nature of the Sun's physical activity is presented. Statistical analysis of a chaotic signal can extract only its most gross features, and detailed physical models fail, since even the simplest equations of motion for a nonlinear system can exhibit chaotic behavior. A recent theory by Feigenbaum suggests that nonlinear systems that can be led into chaotic behavior through a sequence of period-doubling bifurcations will exhibit a universal behavior. As the control parameter is increased, the bifurcation points occur in such a way that a proper ratio of these will approach the universal Feigenbaum number. Experimental evidence supporting the applicability of the Feigenbaum scenario to solar flux data is sparse. However, given the hypothesis that the Sun's convection zones are similar to a Rayleigh-Bernard mechanism, we can learn a great deal from the remarkable agreement observed between the prediction by theory (period doubling - a universal route to chaos) and the amplitude decrease of the signal's regular subharmonics. It is shown that period-doubling-type bifurcation is a possible route to a chaotic pattern of solar flux that is distinguishable from the logarithm of its power spectral density. This conclusion is the first positive step toward a reformulation of solar flux by a nonlinear chaotic approach. The ultimate goal of this research is to be able to predict an estimate of the upper and lower bounds for solar flux within its predictable zones. Naturally, it is an important task to identify the time horizons beyond which predictability becomes incompatible with computability.

Ashrafi, S.↗
NASA NTRS1991

Evidence of chaotic pattern in solar flux through a reproducible sequence of period-doubling-type bifurcations

Presented here is a preliminary study of the limits to solar flux intensity prediction, and of whether the general lack of predictability in the solar flux arises from the nonlinear chaotic nature of the Sun's physical activity. Statistical analysis of a chaotic signal can extract only its most gross features, and detailed physical models fail, since even the simplest equations of motion for a nonlinear system can exhibit chaotic behavior. A recent theory by Feigenbaum suggests that nonlinear systems that can be led into chaotic behavior through a sequence of period-doubling bifurcations will exhibit a universal behavior. As the control parameter is increased, the bifurcation points occur in such a way that a proper ratio of these will approach the universal Feigenbaum number. Experimental evidence supporting the applicability of the Feigenbaum scenario to solar flux data is sparse. However, given the hypothesis that the Sun's convection zones are similar to a Rayleigh-Bernard mechanism, we can learn a great deal from the remarkable agreement observed between the prediction by theory (period doubling - a universal route to chaos) and the amplitude decrease of the signal's regular subharmonics. The authors show that period-doubling-type bifurcation is a possible route to a chaotic pattern of solar flux that is distinguishable from the logarithm of its power spectral density. This conclusion is the first positive step toward a reformulation of solar flux by a nonlinear chaotic approach. The ultimate goal of this research is to be able to predict an estimate of the upper and lower bounds for solar flux within its predictable zones. Naturally, it is an important task to identify the time horizons beyond which predictability becomes incompatible with computability.

Ashrafi, S.↗
DOE OSTI2021

High-Pressure Synthesis of Bulk Cobalt Cementite, Co 3 C

Transition metal carbides find use in a wide range of advanced high-resilience applications including high-strength steels, heat shields, and deep-earth drills. However, carbides of the mid-to-late transition metals remain difficult to isolate and characterize on account of their metastability, which precludes the preparation of high-quality bulk single crystal samples using traditional solid-state methods. Herein, we report a combined computational and experimental survey of the cobalt-carbon binary system under high pressures and demonstrate that pressure offers a route toward the bulk synthesis of the metastable cementite-type cobalt carbide, Co 3 C, which under ambient conditions can only be prepared in low-dimensional thin film or nanoparticle forms. First-principles calculations reveal two competitive low-energy stoichiometric phases under ambient pressures - Pnnm-Co 2 C (Fe 2 C-type) and Pnma-Co 3 C (Fe 3 Ctype) - consistent with the known low-dimensional phases that have been studied for their promising magnetic properties. However, the calculated formation enthalpy of Pnma-Co 3 C decreases steadily with the applied pressure, while that of Pnnm-Co 2 C increases. Here, we pursue these results using high-pressure laser-heated synthesis methods coupled with in situ X-ray diffraction and observe the formation of Pnma-Co 3 C above 4.8 GPa. We determine the experimental bulk modulus of Co 3 C to be K o = 237 GPa (K p = 4.0). First-principles calculations of the phonon modes in Co 3 C reveal dynamical instabilities at ambient pressure that are absent under compression. These results offer a promising new route for the synthesis of rare-earth-free magnets.

36 MATERIALS SCIENCE↗
NASA NTRS1988

Experiences with serial and parallel algorithms for channel routing using simulated annealing

Two algorithms for channel routing using simulated annealing are presented. Simulated annealing is an optimization methodology which allows the solution process to back up out of local minima that may be encountered by inappropriate selections. By properly controlling the annealing process, it is very likely that the optimal solution to an NP-complete problem such as channel routing may be found. The algorithm presented proposes very relaxed restrictions on the types of allowable transformations, including overlapping nets. By freeing that restriction and controlling overlap situations with an appropriate cost function, the algorithm becomes very flexible and can be applied to many extensions of channel routing. The selection of the transformation utilizes a number of heuristics, still retaining the pseudorandom nature of simulated annealing. The algorithm was implemented as a serial program for a workstation, and a parallel program designed for a hypercube computer. The details of the serial implementation are presented, including many of the heuristics used and some of the resulting solutions.

Brouwer, Randall Jay↗
DOE OSTI2016

Hydrothermal Chemistry and Growth of Fergusonite-type RENbO 4 (RE = La–Lu, Y) Single Crystals and New Niobate Hydroxides

A convenient hydrothermal route to high quality single crystals of rare earth orthoniobates RENbO 4 (RE = Y, La–Lu) is discussed. The title compounds can be grown as single crystals in sizes exceeding 2 mm for most of the rare earths using 30 M KOH at temperatures of 700 °C and pressures of 2 kbar. Single crystal X-ray diffraction shows that they all form in the fergusonite structure type, and the structures were solved in space group C 2/ c . Examples based on the largest and smallest rare earth ions in the present study include LaNbO 4 : a = 7.3576(15) Å, b = 11.538(2) Å, c = 5.2128(10) Å, β = 130.900(3)°, Z = 4, R 1 = 0.0162, wR 2 = 0.0405, and LuNbO 4 : a = 6.9805(6) Å, b = 10.8271(8) Å, c = 5.0406(4) Å, β = 131.676(3)°, Z = 4, R 1 = 0.0178, wR 2 = 0.0489. While domain structures are clearly present in the bulk crystals, the domains are much larger than normally reported from high temperature growth methods, and individual single domain crystals on the order of 0.1–1 mm in size can be selected. Rocking curves of these crystals have narrow fwhm and are Gaussian shaped. Several new phases were also isolated as part of the development of the crystal growth chemistry and were characterized by single crystal X-ray diffraction including such examples as K 3 YNb 2 O 7 (OH) 2 : P 6 3 / mmc , a = 5.9770(12) Å, c = 14.901(2) Å, Z = 2, R 1 = 0.0303, wR 2 = 0.0765 and CsNb 2 O 5 (OH): Fd $\bar{3}$ m , a = 10.5869(14) Å, Z = 8, R 1 = 0.0336, wR 2 = 0.0741

36 MATERIALS SCIENCE↗
NASA NTRS1952

Preliminary Survey of Icing Conditions Measured During Routine Transcontinental Airline Operation

Icing data collected on routine operations by four DC-4-type aircraft equipped with NACA pressure-type icing-rate meters are presented as preliminary information obtained from a statistical icing data program sponsored by the NACA with the cooperation of many airline companies and the United States Air Force. The program is continuing on a much greater scale to provide large quantities of data from many air routes in the United States and overseas. Areas not covered by established air routes are also being included in the survey. The four aircraft which collected the data presented in this report were operated by United Air Lines over a transcontinental route from January through May, 1951. An analysis of the pressure-type icing-rate meter was satisfactory for collecting statistical data during routine operations. Data obtained on routine flight icing encounters from.these four instrumented aircraft, although insufficient for a conclusive statistical analysis, provide a greater quantity and considerably more realistic information than that obtained from random research flights. A summary of statistical data will be published when the information obtained daring the 1951-52 icing season and that to be obtained during the 1952-53 season can be analyzed and assembled. The 1951-52 data already analyzed indicate that the quantity, quality, and range of icing information being provided by this expanded program should afford a sound basis for ice-protection-system design by defining the important meteorological parameters of the icing cloud.

Perkins, Porter J.↗
DOE OSTI2017

Crystal chemical characterization of mullite-type aluminum borate compounds

Al-rich aluminum borates were prepared by different synthesis routes using various Al/B ratios, characterized by diffraction methods, spectroscopy and prompt gamma activation analysis. The {sup 11}B NMR data show a small amount of BO{sub 4} species in all samples. The chemical analysis indicates a trend in the Al/B ratio instead of a fixed composition. Both methods indicate a solid solution Al{sub 5−x}B{sub 1+x}O{sub 9} where Al is substituted by B in the range of 1–3%. The structure of B-rich Al{sub 4}B{sub 2}O{sub 9} (C2/m, a=1488 pm, b=553 pm, c=1502 pm, ß=90.6°), was re-investigated by electron diffraction methods, showing that structural details vary within a crystallite. In most of the domains the atoms are orderly distributed, showing no signal for the postulated channel oxygen atom O5. The absence of O5 is supported by density functional theory calculations. Other domains show a probable disordered configuration of O5 and O10, indicated by diffuse scattering along the b direction. - Graphical abstract: Projections of three-dimensional electron diffraction space of Al{sub 4}B{sub 2}O{sub 9} along the main directions. - Highlights: • The crystal structure of Al{sub 4}B{sub 2}O{sub 9} was re-evaluated. • Structural details vary among different crystals and inside Al{sub 4}B{sub 2}O{sub 9} crystallites. • Diffuse scattering indicate a probable disordered configuration of O5 and O10. • A solid solution series for Al{sub 5−x}B{sub x}O{sub 9} is indicated by PGAA and NMR spectroscopy. • The presence of BO{sub 4} groups is confirmed by {sup 11}B MAS NMR spectroscopy for Al{sub 5−x}B{sub 1+x}O{sub 9}.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1992

Annoyance caused by aircraft en route noise

A laboratory experiment was conducted to quantify the annoyance response of people on the ground to enroute noise generated by aircraft at cruise conditions. The en route noises were ground level recordings of eight advanced turboprop aircraft flyovers and six conventional turbofan flyovers. The eight advanced turboprop enroute noises represented the NASA Propfan Test Assessment aircraft operating at different combinations of altitude, aircraft Mach number, and propeller tip speed. The conventional turbofan en route noises represented six different commercial airliners. The overall durations of the en route noises varied from approximately 40 to 160 sec. In the experiment, 32 subjects judged the annoyance of the en route noises as well as recordings of the takeoff and landing noises of each of 5 conventional turboprop and 5 conventional turbofan aircraft. Each of the noises was presented at three sound pressure levels to the subjects in an anechoic listening room. Analysis of the judgments found small differences in annoyance between three combinations of aircraft type and operation. Current tone and corrections did not significantly improve en route annoyance prediction. The optimum duration-correction magnitude for en route noise was approximately 1 dB per doubling of effective duration.

Mccurdy, David A.↗