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Results for “density maps”

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 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

The derivation of temperature gradient and electron density maps from EUV spectroheliograms.

We discuss spatial variations in electron density at the base of the corona and in the temperature gradient in the chromospheric-coronal transition layer as determined from analysis of maps constructed from Mg X and O VI spectroheliograms. Both the mapping techniques and results of analyzing EUV spectra from OSO 6 observations are presented. Comparisons of these maps with photospheric magnetograms and spectroheliograms made in chromospheric EUV lines and continua indicate that the electron density and temperature gradient in the transition layer tend to be enhanced in areas where the photospheric magnetic field and chromospheric EUV emission are enhanced. Relationships among the coronal electron density, transition-layer temperature gradient, chromospheric emission, and photospheric magnetic field strength are derived.

Withbroe, G. L.↗
NASA NTRS2005

Image of Fomalhaut Dust Ring at 350 Microns: The Relative Column Density Map Shows Pericenter-Apocenter Asymmetry

We have imaged the circumstellar disk of Fomalhaut at 350 mm wavelength, using SHARC II (Submillimeter High Angular Resolution Camera II) at the Caltech Submillimeter Observatory. The spatial resolution of the raw images (9") has been enhanced by a factor of 3 using the HiRes deconvolution procedure. We find that at this wavelength and signal-to-noise ratio (approx.12), the observed morphology is that of a simple inclined ring (i approx. 70 deg), with little or no other apparent structure--this is the first observation that shows clearly the ring morphology of the disk. We have combined our 350 mm data with Spitzer Space Telescope images at 24, 70, and 160 mm in order to estimate the two-dimensional spatial variation of relative column density ("tau map") using our DISKFIT procedure. The tau map is based on the following physical assumptions: (1) the wavelength variation of opacity is the same throughout the disk, (2) the radial variation of dust temperature is dictated by the energy balance of individual grains in the stellar radiation field, and (3) the vertical scale height of the disk follows a power-law radial variation. The results confirm the ringlike morphology but also show that the geometric center is displaced from the star by about 8 AU and that the ring has an apocentric enhancement of approximately 14% in integrated column density. If we interpret the displacement in terms of elliptical orbital motion due to gravitational perturbation by an unseen planet, then the implied forced eccentricity is ~0.06; dynamical modeling then predicts an apocentric density enhancement consistent with that inferred from the tau map.

Fomalhaut↗
NASA NTRS1978

Plasma density mapping in the solar wind through use of VHF radio to measure electron content

How the electron content between the Solar probe and the earth can be observed with a minimum of equipment and give a quantitative rationale for the use of a signal near 400 MHz to supplement the telecommunications signal is described. The emphasis is on the method of making content observations and on their value. While far from the Sun, the electron content is so low that the S-X dual-frequency system is insufficiently sensitive and a UHF system is optimum. As the probe approaches the Sun, the UHF may be disrupted by scintillation and the variations of the telecommunications signal must be used for the content measurement. By operating the suggested system in different modes as the solar distance changes, operation during the entire mission is possible.

Croft, T. A.↗
NASA NTRS1974

Identification of irrigated crop types from ERTS-1 density contour maps and color infrared aerial photography

The author has identified the following significant results. The crop types of a Great Plains study area were mapped from color infrared aerial photography. Each field was positively identified from field checks in the area. Enlarged (50x) density contour maps were constructed from three ERTS-1 images taken in the summer of 1973. The map interpreted from the aerial photography was compared to the density contour maps and the accuracy of the ERTS-1 density contour map interpretations were determined. Changes in the vegetation during the growing season and harvest periods were detectable on the ERTS-1 imagery. Density contouring aids in the detection of such charges.

Marrs, R. W.↗
NASA NTRS2010

Effect of Anatomical Modeling on Space Radiation Dose Estimates: A Comparison of Doses for NASA Phantoms and 5th, 50th, and 95th Percentile UF Hybrid Phantoms

The estimate of absorbed dose to individual organs of a space crewmember is affected by the geometry of the anatomical model of the astronaut used in the radiation transport calculation. For astronaut dosimetry, NASA currently uses the computerized anatomical male (CAM) and computerized anatomical female (CAF) stylized phantoms to represent astronauts in its operational radiation dose analyses. These phantoms are available in one size and in two body positions. In contrast, the UF Hybrid Adult Male and Female (UFHADM and UFHADF) phantoms have organ shapes based on actual CT data. The surfaces of these phantoms are defined by non-uniform rational B-spline surfaces, and are thus flexible in terms of body morphometry and extremity positioning. In this study, UFHADM and UFHADF are scaled to dimensions corresponding to 5th, 50th, and 95th percentile (PCTL) male and female astronauts. A ray-tracing program is written in Visual Basic 2008, which is then used to create areal density maps for dose points corresponding to various organs within the phantoms. The areal density maps, along with appropriate space radiation spectra, are input into the NASA program couplet HZETRN/BRYNTRN, and organ doses are calculated. The areal density maps selected tissues and organs of the 5th, 50th, and 95th PCTL male and female phantoms are presented and compared. In addition, the organ doses for the 5th, 50th, and 95th PCTL male and female phantoms are presented and compared to organ doses for CAM and CAF.

Bahadori, A.↗
NASA NTRS1973

Land use, forest density, soil mapping, erosion, drainage, salinity limitations

The author has identified the following significant results. The results of analyses show that it is possible to obtain information of practical significance as follows: (1) A quick and accurate estimate of the proper use of the valuable land can be made on the basis of temporal and spectral characteristics of the land features. (2) A rather accurate delineation of the major forest formations in the test areas was achieved on the basis of spatial and spectral characteristics of the studied areas. The forest stands were separated into two density classes; dense forest, and broken forest. On the basis of ERTS-1 data and the existing ground truth information a rather accurate mapping of the major vegetational forms of the mountain ranges can be made. (3) Major soil formations are mapable from ERTS-1 data: recent alluvial soils; soil on quarternary deposits; severely eroded soil and lithosol; and wet soils. (4) An estimation of cost benefits cannot be made accurately at this stage of the investigation. However, a rough estimate of the ratio of the cost for obtaining the same amount information from ERTS-1 data and from conventional operations would be approximately 1:6 to 1:10, in favor of the ERTS-1.

Yassoglou, N. J.↗
NASA NTRS1978

Ages of flow units in the far eastern maria and implications for basin-filling history

The spatial distribution of major units of uniform relative age exposed in the far eastern maria and Mare Humorum was determined using a crater density mapping technique. Correlation of crater densities and radiometric ages of Apollo and Luna landing sites provided estimates of the absolute ages for the units. The combination of such data with relative age data from previous crater morphology studies produced a complete map of the distribution of major age units in the lunar near-side maria. The map shows that there are young (2.5 + or - 0.5 billion years old) mare basalts in the eastern maria, although most young flows occur in the western maria. The vents for the young flows generally are found along the edges of basins. Because old mare units (greater than 3.5 billion years old) are also commonly found around the edges of the basins, it is suggested that the basins were subsiding during filling, probably as a result of isostatic compensation due to the weight of the lava.

Boyce, J. M.↗
NASA NTRS1979

Chlorophyll gradient map from high-altitude ocean-color-scanner data

A chlorophyll density map of an ocean area 25 x 30 km is presented, and the procedure used in generating the map from high-altitude ocean-color-scanner data is discussed. Data were obtained from a ten-channel radiometer on board a U-2 aircraft flying at 19.8 km above the coastal waters of Monterey Bay, California under conditions of clear skies and clear and deep water; the processing algorithms should be useful for satellite data as well. The total radiance measured at high altitude was separated into an atmospheric and sea-surface component and a water component, which is associated with chlorophyll content, for each pixel using the upwelling radiance of a near IR channel to estimate the atmospheric effect. Chlorophyll data were extracted by taking the ratio of the difference of intensities in the 472 and 506 nm channels to the sum of the channels, and are found to agree with shipboard chlorophyll determinations at a depth of 5 m.

Kim, H. H.↗
NASA NTRS2022

Simons Observatory: Constraining inflationary gravitational waves with multitracer B-mode delensing

We introduce and validate a delensing framework for the Simons Observatory (SO), which will be used to improve constraints on inflationary gravitational waves by reducing the lensing noise in measurements of the B modes in CMB polarization. SO will initially observe CMB by using three small aperture telescopes and one large-aperture telescope. While polarization maps from small-aperture telescopes will be used to constrain inflationary gravitational waves, the internal CMB lensing maps used to delens will be reconstructed from data from the large-aperture telescope. Since lensing maps obtained from the SO data will be noise dominated on subdegree scales, the SO lensing framework constructs a template for lensing-induced B modes by combining internal CMB lensing maps with maps of the cosmic infrared background from Planck as well as galaxy density maps from the LSST survey. We construct a likelihood for constraining the tensor-to-scalar ratio r that contains auto and cross spectra between observed B modes and the lensing B-mode template. We test our delensing analysis pipeline on map-based simulations containing survey nonidealities, but that, for this initial exploration, does not include contamination from Galactic and extragalactic foregrounds. We find that the SO survey masking and inhomogeneous and atmospheric noise have very little impact on the delensing performance, and the r constraint becomes σ(r)≈0.0015 which is close to that obtained from the idealized forecasts in the absence of the Galactic foreground and is nearly a factor of 2 tighter than without delensing. We also find that uncertainties in the external large-scale structure tracers used in our multitracer delensing pipeline lead to bias much smaller than the 1σ statistical uncertainties.

Toshiya Namikawa↗
NASA NTRS1974

Three-dimensional tertiary structure of yeast phenylalanine transfer RNA

Results of an analysis and interpretation of a 3-A electron density map of yeast phenylalanine transfer RNA. Some earlier detailed assignments of nucleotide residues to electron density peaks are found to be in error, even though the overall tracing of the backbone conformation of yeast phenylalanine transfer RNA was generally correct. A new, more comprehensive interpretation is made which makes it possible to define the tertiary interactions in the molecule. The new interpretation makes it possible to visualize a number of tertiary interactions which not only explain the structural role of most of the bases which are constant in transfer RNAs, but also makes it possible to understand in a direct and simple fashion the chemical modification data on transfer RNA. In addition, this pattern of tertiary interactions provides a basis for understanding the general three-dimensional folding of all transfer RNA molecules.

Kim, S. H.↗
NASA NTRS1997

The great annihilator 1E 1740.7-2942: Molecular cloud connection and coronal structure

Using (12)CO and (13)CO observations, column density maps of the molecular cloud in the direction of 1E 1740.7-2942 are presented. Hydrogen column densities of the cloud vary between N(sub H) = 3.5 x 10(exp 22)/cu cm and 11 x 10(exp 22)/cu cm, depending on the method employed. From this, it is concluded that, despite the weakness of the iron fluorescent 6.4 keV line, the source may lie inside the cloud, or at least close to its edge. The combined spectra from the Advanced Satellite for Cosmology and Astrophysics (ASCA) and the burst and transient source experiment (BATSE) can be modeled with a two phase accretion disk corona model, where the hot region is detached from the cold disk. Geometrically, the hot phase can be interpreted as a number of active regions above the disk, or as a spherical hot cloud about the central object.

Vilhu, Osmi↗
NASA NTRS1999

A Diagnostic Analysis of the Kennedy Space Center LDAR Network

The performance characteristics of the Kennedy Space Center Lightning Detection and Ranging (LDAR) network are investigated at medium-far range (50-300 km). A 19 month noise-filtered sample of LDAR observations is examined, from which it is determined that the "climatological" VHF source density as observed by LDAR falls off approximately 10 dB every 71 km of ground range from the network centroid. The underlying vertical distribution of LDAR sources is approximately normally distributed with a mean of 9 km and a standard deviation of 2.7 km, implying that loss of below-horizon sources has a negligible effect on column-integrated source densities within 200 km ground range. At medium to far ranges, location errors are primarily radial and have a slightly asymmetric distribution whose first moment increases as r(exp 2). A range calibration derived from these results is used to normalize source density maps on monthly, daily and hourly time scales and yields significant improvements in correlation with NLDN ground strike densities.

Boccippio, Dennis J.↗
NASA NTRS1992

Analysis of interstellar cloud structure based on IRAS images

The goal of this project was to develop new tools for the analysis of the structure of densely sampled maps of interstellar star-forming regions. A particular emphasis was on the recognition and characterization of nested hierarchical structure and fractal irregularity, and their relation to the level of star formation activity. The panoramic IRAS images provided data with the required range in spatial scale, greater than a factor of 100, and in column density, greater than a factor of 50. In order to construct densely sampled column density maps of star-forming clouds, column density images of four nearby cloud complexes were constructed from IRAS data. The regions have various degrees of star formation activity, and most of them have probably not been affected much by the disruptive effects of young massive stars. The largest region, the Scorpius-Ophiuchus cloud complex, covers about 1000 square degrees (it was subdivided into a few smaller regions for analysis). Much of the work during the early part of the project focused on an 80 square degree region in the core of the Taurus complex, a well-studied region of low-mass star formation.

Scalo, John M.↗