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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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NASA NTRS2005

A1367: A Cluster in Formation

A1367 is a puzzling cluster with a large elongation, suggesting a major merger but with an anti-correlation between the luminosity and temperature of the two components of the cluster (NE and SW). The less luminous subconcentration appears hotter and the more luminous portion of the cluster appears cooler in contradiction to the well-established positive correlation of temperature and luminosity for clusters and groups. A1367 lies at the intersection of two large scale filaments in our local Universe - one in the direction of the Coma cluster and a second in the direction of the Virgo cluster. The elongation of the main X-ray structure lies along the Virgo-A1367 filament. With the XMM-Newton observation we have developed a model involving multiple mergers from two directions to explain the observed features of A1367.

Mushotzky, Richard↗
NASA NTRS2005

Satellite and Ground System Solutions at Your Fingertips

In the summer of 1998, the blockbuster action movie Armageddon captivated audiences with a thrilling doomsday plot about a meteor the size of Texas that was racing towards the Earth. Though the premise of the movie was purely fictional, the unfortunate reality is that near-Earth asteroids such as the one portrayed in the film do exist. On December 23, 2004, NASA announced that an asteroid it anticipated to pass near the Earth on April 13, 2029, had been assigned the highest score to date on the universally used Torino Impact Hazard Scale. At first, the flyby distance for the asteroid, dubbed MN4, was uncertain and an Earth impact could not be ruled out. The odds of impact were initially believed to be 1 in 300, high enough to merit special monitoring by astronomers around the world, but were then escalated to 1 in 37 on December 27. NASA officials noted, however, that these odds should not be of public concern, since they were likely to change on a day-to-day basis as new data were received. The officials were correct in their assertion, as any chances of an impact with Earth in 2029 were completely ruled out later that same day. Integral Systems, Inc., a leading provider of satellite ground systems and the first company to offer an integrated suite of commercial-off-the-shelf software products for satellite command and control, is helping NASA keep a careful watch for any close-encountering asteroids with its tracking technology. The company supported the first NASA Discovery mission, the Near Earth Asteroid Rendezvous (NEAR) program, back in 1996, and has expanded its business by building more ground systems for a greater variety of satellites than any other company in the world. (NASA has since launched seven more Discovery missions, with the eighth lifting off earlier this year.) The experience gained from the company s participation in developing satellite command and control ground systems for the NEAR program has bolstered its flagship product line, the EPOCH Integrated Product Suite (IPS), first featured in Spinoff 1997, and led to the creation of its latest product, the Skylight Direct Broadcast Ground Terminal.

Source record↗
NASA NTRS2016

OH PLIF Visualization of a Premixed Ethylene-fueled Dual-Mode Scramjet Combustor

Hydroxyl radical (OH) planar induced laser fluorescence (PLIF) measurements have been performed in a small-scale scramjet combustor at the University of Virginia Aerospace Research Laboratory at nominal simulated Mach 5 enthalpy. OH lines were carefully chosen to have fluorescent signal that is independent of pressure and temperature but linear with mole fraction. The OH PLIF signal was imaged in planes orthogonal to and parallel to the freestream flow at different equivalence ratios. Flameout limits were tested and identified. Instantaneous planar images were recorded and analyzed to compare the results with width increased dual-pump enhanced coherent anti-Stokes Raman spectroscopy (WIDECARS) measurements in the same facility and large eddy simulation/Reynolds average Navier-Stokes (LES/RANS) numerical simulation. The flame angle was found to be approximately 10 degrees for several different conditions, which is in agreement with numerical predictions and measurements using WIDECARS. Finally, a comparison between NO PLIF non-combustion cases and OH PLIF combustion cases is provided: the comparison reveals that the dominant effect of flame propagation is freestream turbulence rather than heat release and concentration gradients.

Cantu, Luca M. L.↗
NASA NTRS2015

Nitric Oxide PLIF Visualization of Simulated Fuel-Air Mixing in a Dual-Mode Scramjet

Nitric oxide (NO) planar induced laser fluorescence (PLIF) measurements have been performed in a small scale scramjet combustor at the University of Virginia Aerospace Research Laboratory at nominal simulated Mach 5 flight. A mixture of NO and N2 was injected at the upstream end of the inlet isolator as a surrogate for ethylene fuel, and the mixing of this fuel simulant was studied with and without a shock train. The shock train was produced by an air throttle, which simulated the blockage effects of combustion downstream of the cavity flame holder. NO PLIF signal was imaged in a plane orthogonal to the freestream at the leading edge of the cavity. Instantaneous planar images were recorded and analyzed to identify the most uniform cases, which were achieved by varying the location of the fuel injection and shock train. This method was used to screen different possible fueling configurations to provide optimized test conditions for follow-on combustion measurements using ethylene fuel. A theoretical study of the selected NO rotational transitions was performed to obtain a LIF signal that is linear with NO mole fraction and approximately independent of pressure and temperature.

Cantu, Luca M. L.↗
NASA NTRSDate not supplied

NASA GeneLab: Open Science for Life in Space

The NASA GeneLab project capitalizes on multi-omic technologies to maximize the return on spaceflight experiments. To do this, GeneLab maintains a publicly accessible database (GLDS) that houses spaceflight and spaceflight relevant multi-omics data and collaborates with NASA principal investigators and projects to generate additional omics data. GeneLab houses more than 350 transcriptomic, proteomic, metabolomic and epigenomic datasets from plant, animal and microbial experiments, with a growing number of these having been produced by the GeneLab Sequencing Lab. The GLDS contains rich metadata about each experiment and has integrated radiation dosimetry data from experiments flown on the Space Shuttle, International Space Station, and Free Flying spacecrafts. With the increasing amount and complexity of omics data being generated, GeneLab utilizes community-defined, common models for metadata and terminology so that omics data and results are discoverable and reliably reproducible. GeneLab uses the ISA-Tab specification and semantic model for organizing and representing omics metadata. In addition to metadata standards, data files must be open-source file or common exchange formats to ensure accessibility and usability by all users. To ease data ingestion and transfer, the web-based submission tool allows PIs a user-friendly user interface to curate, organize, and publish their space relevant omics data. In the more recent years, data curation and submission portal has incorporated the FAIR principles making data findable, accessible, interoperable, and reusable. To increase reusability of data, GeneLab has implemented an effort to present processed data in the GLDS in addition to the raw omics data. The processed data will enable interpretation of the data by a larger group of students, scientists and the general public. Standard pipelines for the transformation of raw data into visualizations were developed by four GeneLab Analysis Working Groups (animals, plants, microbes, multi-omics) comprised of over 200 scientists from NASA, industry, and academia. To explore the data, the GLDS provides users various tools for data analysis, collaborative workspace for file storage and sharing, and a visualization portal. The analysis platform built using the Galaxy toolshed provides access to a broad variety of users including those with limited bioinformatics experience and students to learn how to analyze spaceflight omics data. The visualization portal takes GeneLab one step closer to data democratization by removing all bioinformatics requisites to interpret transcriptomics data hosted in the repository. To train the next generation of scientists, NASA offers training programs such as GeneLab 4 High School (GL4HS) and GeneLab 4 Universities. NLM Curation at a Scale Workshop 2022 | NASA GeneLab (GL4U) to teach students bioinformatics and computational biology methods to analyze omics data. Discoveries made using GeneLab have begun and will continue to deepen our understanding of biology, advance the field of genomics, and help to discover cures for diseases, create better diagnostic tools, and ultimately allow astronauts to better withstand the rigors of long-duration spaceflight.

GeneLab↗
NASA NTRS2004

An Expanded RXTE Survey of Long-Term X-ray Variability in Seyfert 1 Galaxies

The first seven years of RXTE monitoring of Seyfert 1 active galactic nuclei have been systematically analyzed to yield five homogenous samples of 2-12 keV light curves, probing hard X-ray variability on successively longer durations from approx. 1 day to approx. 3.5 years. 2-10 keV variability on time scales of approx. 1 day, as probed by ASCA, are included. All sources exhibit stronger X-ray variability towards longer time scales, with variability amplitudes saturating at the longest time scales, but the increase is greater for relatively higher luminosity sources. The well-documented anticorrelation between variability amplitude and luminosity is confirmed on all time scales. However, anticorrelations between variability amplitude and black hole mass estimate are evident on only the shortest time scales probed. The data are consistent with the models of power spectral density (PSD) movement described in Markowitz et al. (2003) and McHardy et al. (2004), whereby Seyfert 1 galaxies variability can be described by a single, universal PSD shape whose cutoff frequency scales with black hole mass. The best-fitting scaling relations between variability time scale, black hole mass and X-ray luminosity support an average accretion rate of 2% of the Eddington limit for the sample. Nearly all sources exhibit stronger variability in the relatively soft 2-4 keV band compared to the 7-12 keV band on all time scales. Color-flux diagrams support also Seyfert 1s' softening as they brighten. There are indications that relatively less luminous or less massive sources exhibit a greater degree of spectral variability for a given increase in overall flux.

Markowitz, A.↗
NASA NTRS1995

Cosmological implications of ROSAT observations of groups and clusters of galaxies

We have combined ROSAT Position Sensitive Proportional Counter (PSPC) and optical observations of a sample of groups and clusters of galaxies to determine the fundamental parameters of these systems (e.g., the dark matter distribution, gas mass fraction, baryon mass fraction, mass-to-light ratio, and the ratio of total-to-luminous mass). Imaging X-ray spectroscopy of groups and clusters show that the gas is essentially isothermal beyond the central region, indicating that the total mass density (mostly dark matter) scales as rho(sub dark) varies as 1/r squared. The density profile of the hot X-ray emitting gas is fairly flat in groups with rho(sub gas) varies as 1/r and becomes progressively steeper in hotter richer systems, with rho(sub gas) varies as 1/r squared in the richest clusters. These results show, that in general, the hot X-ray-emitting gas is the most extended mass component in groups and clusters, the galaxies are the most centrally concentrated component, and the dark matter is intermediate between the two. The flatter density rofile of the hot gas compared to the dark matter produces a gas mass fraction that increases with radius within each object. There is also a clear trend of increasing gas mass fraction (from 2% to 30%) between elliptical galaxies and rich clusters due to the greater detectable extent of the X-ray emission in richer systems. For the few systems in which the X-ray emission can be traced to the virial radius (where the overdensity delta is approximately equal 200), the gas mass fraction (essentially the baryon mass fraction) approaches a roughly constant value of 30%, suggesting that this is the true primordial value. Based on standard big bang nucleosynthesis, the large baryon mass fraction implies that Omega = 0.1 - 0.2. The antibiased gas distribution suggests that feedback from galaxy formation and hydrodynamics play important roles in the formation of structure on the scale of galaxies to rich clusters. All the groups and clusters in our sample have mass-to-light ratios of M/L(sub V) approximately 100 - 150 solar mass/solar luminosity, which strongly contrasts with the traditional view that the mass-to-light ratio of rich clusters is significantly greater than individual galaxies or groups with M/L(sub V) approximately 250 - 300 solar mass/solar luminosity. We also show that M/L(sub V is essentially constant within the virial radius of clusters (where delta is greater than or approximately 200), which is consistent with the peaks formalism of biased galaxy formation. While the mass-to-light ratios of groups and clusters are comparable (indicating a constant mass fraction of optically luminous material), the ratio of the total mass-to-luminous mass (gas plus stars) monotonically decreases between galaxies and clusters. The decrease in M(sub total)/M(sub lum) arises from two factors: (1) the composition of baryonic matter varies from a predominance of optically luminous material (stars) on the scale of galaxies (approximately 10 kpc) to a predominance of X-ray luminous material (hot gas) on the scale of rich clusters (approximately 1 Mpc), and (2) the hot gas has a more extended spatial distribution than the gravitating matter. The observed decrease M(sub total)/M(sub lum) between galaxies and clusters indicates that the universe actually becomes `brighter' on mass scales between 10(exp 12) and 10(exp 15) solar mass, in the sense that a greater fraction of the gravitating mass is observable.

David, Laurence P.↗
NASA NTRS1985

Large-scale computations in fluid mechanics; Proceedings of the Fifteenth Summer Seminar on Applied Mathematics, University of California, La Jolla, CA, June 27-July 8, 1983. Parts 1 & 2

Papers are presented on such topics as the use of semi-Lagrangian advective schemes in meteorological modeling; computation with high-resolution upwind schemes for hyperbolic equations; dynamics of flame propagation in a turbulent field; a modified finite element method for solving the incompressible Navier-Stokes equations; computational fusion magnetohydrodynamics; and a nonoscillatory shock capturing scheme using flux-limited dissipation. Consideration is also given to the use of spectral techniques in numerical weather prediction; numerical methods for the incorporation of mountains in atmospheric models; techniques for the numerical simulation of large-scale eddies in geophysical fluid dynamics; high-resolution TVD schemes using flux limiters; upwind-difference methods for aerodynamic problems governed by the Euler equations; and an MHD model of the earth's magnetosphere.

Engquist, B. E.↗
NASA NTRS1985

Kolmogorov and scalar spectral regimes in numerical turbulence

Velocity and passive-scalar spectra for turbulent fields generated by a forced three-dimensional simulation and Taylormicroscale Reynolds numbers up to 83 are shown to have distinct spectral regimes, including a Kolmogorov inertial subrange. Both one- and three-dimensional spectra are shown for comparison with experiment and theory, respectively. When normalized by the Kolmogorov dissipation scales velocity spectra collapse to a single curve and a high-wavenumber bulge is seen. The bulge leads to an artificially high Kolmogorov constant, but is consistent with recent measurements of the velocity spectrum in the dissipation regime and the velocity-derivative skewness. Scalar spectra, when normalized by the Oboukov-Corrsin scales, collapse to curves which depend only on Prandtl number and show a universal inertial-convective subrange, independent of Prandtl number. When normalized by the Batchelor scales, the scalar spectra show a universal dissipation regime which is independent of Prandtl numbers from 0.1 to 1.0. The time development of velocity spectra is illustrated by energy-transfer spectra in which distinct pulses propagate to high wavenumbers.

Kerr, R. M.↗
NASA NTRS1990

Universal energy relations and metal/ceramic interfaces

Known general relationships between pertinent variables are applied to investigate metal-ceramic interfaces. The adhesive energy is determined. The electronic exchange-correlation energy is found to be the dominant attractive term in the total energy. Results for the adhesive energy are obtained for junctions of all combinations of the low index surfaces of Al,Na, Mg, and Zn. This leads to a variety of curves, all with a single minimum of separation and equilibrium binding energy. Scaling results for 10 contacts fall closely onto a single curve, a universal energy relation for adhesion. The scaled chemisorption curves fall accurately on the same universal form that was found for adhesion. For the case of cohesion, all-first principle results are scaled and again all scaled curves for a variety of metals fall accurately on the universal form for adhesion and chemisorption. An intimate relationship between the energetics of solids and molecules is inferred.

Smith, John R.↗
NASA NTRS1990

Minimal spectrum of long-wave perturbations - Is linear growth correct only in the nonlinear regime?

Very high resolution two-dimensional simulations are used to test the generation and growth of the so-called 'minimal' k exp 4 power spectrum which develops from initial conditions which have power only on small scales, such as might result from some process in the early universe. It is confirmed that the amplitude of minimal long-wave power grows proportionally to a exp 4, not a-squared, where a is the scale factor of the expanding universe. It reverts to a-squared only after the short-wave modes are effectively saturated, and by that time an effective long-wave power law closer to k-cubed is found. Small-scale perturbations may result in much more long-wave power than has been generally assumed.

Shandarin, Sergei F.↗
NASA NTRS1995

Korea's developmental program for superconductivity

Superconductivity research in Korea was firstly carried out in the late 70's by a research group in Seoul National University (SNU), who fabricated a small scale superconducting magnetic energy storage system under the financial support from Korea Electric Power Company (KEPCO). But a few researchers were involved in superconductivity research until the oxide high Tc superconductor was discovered by Bednorz and Mueller. After the discovery of YBaCuO superconductor operating above the boiling point of liquid nitrogen (77 K)(exp 2), Korean Ministry of Science and Technology (MOST) sponsored a special fund for the high Tc superconductivity research to universities and national research institutes by recognizing its importance. Scientists engaged in this project organized 'High Temperature Superconductivity Research Association (HITSRA)' for effective conducting of research. Its major functions are to coordinate research activities on high Tc superconductivity and organize the workshop for active exchange of information. During last seven years the major superconductivity research has been carried out through the coordination of HITSRA. The major parts of the Korea's superconductivity research program were related to high temperature superconductor and only a few groups were carrying out research on conventional superconductor technology, and Korea Atomic Energy Research Institute (KAERI) and Korea Electrotechnology Research Institute (KERI) have led this research. In this talk, the current status and future plans of superconductivity research in Korea will be reviewed based on the results presented in interim meeting of HITSRA, April 1-2, 1994. Taejeon, as well as the research activity of KAERI.

Hong, Gye-Won↗
NASA NTRS1989

Void statistics, scaling, and the origins of large-scale structure

The probability that a volume of the universe of given size and shape spaced at random will be void of galaxies is used here to study various models of the origin of cosmological structures. Numerical simulations are conducted on hot-particle and cold-particle-modulated inflationary models with and without biasing, on isothermal or initially Poisson models, and on models where structure is seeded by loops of cosmic string. For the Pisces-Perseus redshift compilation of Giovanelli and Haynes (1985), it is found that hierarchical scaling is obeyed for subsamples constructed with different limiting magnitudes and subsamples taken at random. This result confirms that the hierarchical ansatz holds valid to high order and supports the idea that structure in the observed universe evolves by a regular process from an almost Gaussian primordial state. Neutrino models without biasing show the effect of a strong feature in the initial power spectrum. Cosmic string models do not agree well with the galaxy data.

Fry, J. N.↗
NASA NTRS1975

Solar stills for agricultural purposes

Basic concepts of using desalinated water for agricultural purposes are outlined. A mathematical model describing heat and mass transfer in a system combining a solar still with a greenhouse, its solution, and test results of a small-scale unit built at the Middle East Technical University, Ankara, Turkey, are discussed. The unit was employed to demonstrate the technical feasibility of the system. Further development and modifications are necessary for larger-scale operations. The basis of an optimization study which is underway at the Brace Research Institute of McGill University in Montreal, Canada, aimed at finding the best combination of design and operation parameters is also presented.

Selcuk, M. K.↗
NASA NTRS2017

Structure in the 3D Galaxy Distribution. III. Fourier Transforming the Universe: Phase and Power Spectra

We demonstrate the effectiveness of a relatively straightforward analysis of the complex 3D Fourier transform of galaxy coordinates derived from redshift surveys. Numerical demonstrations of this approach are carried out on a volume-limited sample of the Sloan Digital Sky Survey redshift survey. The direct unbinned transform yields a complex 3D data cube quite similar to that from the Fast Fourier Transform of finely binned galaxy positions. In both cases, deconvolution of the sampling window function yields estimates of the true transform. Simple power spectrum estimates from these transforms are roughly consistent with those using more elaborate methods. The complex Fourier transform characterizes spatial distributional properties beyond the power spectrum in a manner different from (and we argue is more easily interpreted than) the conventional multipoint hierarchy. We identify some threads of modern large-scale inference methodology that will presumably yield detections in new wider and deeper surveys.

Galaxies↗
NASA NTRS2017

Structure in the 3D Galaxy Distribution: III. Fourier Transforming the Universe: Phase and Power Spectra

We demonstrate the effectiveness of a relatively straightforward analysis of the complex 3D Fourier transform of galaxy coordinates derived from redshift surveys. Numerical demonstrations of this approach are carried out on a volume-limited sample of the Sloan Digital Sky Survey redshift survey. The direct unbinned transform yields a complex 3D data cube quite similar to that from the Fast Fourier Transform (FFT) of finely binned galaxy positions. In both cases deconvolution of the sampling window function yields estimates of the true transform. Simple power spectrum estimates from these transforms are roughly consistent with those using more elaborate methods. The complex Fourier transform characterizes spatial distributional properties beyond the power spectrum in a manner different from (and we argue is more easily interpreted than) the conventional multi-point hierarchy. We identify some threads of modern large scale inference methodology that will presumably yield detections in new wider and deeper surveys.

Galactic clusters↗
NASA NTRS1989

Mapping the universe

Maps of the galaxy distribution in the nearby universe reveal large coherent structures. The extent of the largest features is limited only by the size of the survey. Voids with a density typically 20 percent of the mean and with diameters of 5000 km/s are present in every survey large enough to contain them. Many galaxies lie in thin sheet-like structures. The largest sheet detected so far is the 'Great Wall' with a minimum extent of 60/h Mpc x 170/h Mpc, where h is the Hubble constant in units of 100 km/s per Mpc. The frequent occurrence of these structures is one of several serious challenges to our current understanding of the origin and evolution of the large-scale distribution of matter in the universe.

Geller, Margaret J.↗
NASA NTRS1986

On the distance measure for gravitational lenses

A discussion is presented of some of the physical elements that are important for geometric optics in curved space-time, with a view toward interpreting data on gravitational lenses. This is important because each gravitational lens provides geometrical information about an arc that crosses a substantial portion of the universe. The propagation of photons along long arcs is highly sensitive to the mean density in the beam, averaged along the arc. Fluctuations about this mean are not important unless their scale is comparable to that of the universe. Tidal distortion is important if only a few lumps are involved. The variation in the geometrical optics is considerably greater if there is a nonzero cosmological constant.

Alcock, C.↗