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At least 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Tm(CuGe)2 by Materials Project

TmCu2Ge2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Tm is bonded in a 8-coordinate geometry to eight equivalent Cu and eight equivalent Ge atoms. All Tm–Cu bond lengths are 3.28 Å. All Tm–Ge bond lengths are 3.09 Å. Cu is bonded to four equivalent Tm and four equivalent Ge atoms to form a mixture of distorted edge, corner, and face-sharing CuTm4Ge4 tetrahedra. All Cu–Ge bond lengths are 2.43 Å. Ge is bonded in a 9-coordinate geometry to four equivalent Tm, four equivalent Cu, and one Ge atom. The Ge–Ge bond length is 2.44 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Tm(CuGe)2 by Materials Project

TmCu2Ge2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Tm is bonded in a 8-coordinate geometry to eight equivalent Cu and eight equivalent Ge atoms. All Tm–Cu bond lengths are 3.14 Å. All Tm–Ge bond lengths are 3.26 Å. Cu is bonded in a 9-coordinate geometry to four equivalent Tm, one Cu, and four equivalent Ge atoms. The Cu–Cu bond length is 2.33 Å. All Cu–Ge bond lengths are 2.47 Å. Ge is bonded in a 4-coordinate geometry to four equivalent Tm and four equivalent Cu atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Tm(CoGe)2 by Materials Project

TmCo2Ge2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Tm is bonded in a 8-coordinate geometry to eight equivalent Co and eight equivalent Ge atoms. All Tm–Co bond lengths are 3.20 Å. All Tm–Ge bond lengths are 3.06 Å. Co is bonded to four equivalent Tm and four equivalent Ge atoms to form a mixture of distorted face, edge, and corner-sharing CoTm4Ge4 tetrahedra. All Co–Ge bond lengths are 2.33 Å. Ge is bonded in a 9-coordinate geometry to four equivalent Tm, four equivalent Co, and one Ge atom. The Ge–Ge bond length is 2.55 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Tm(ClO4)3 by Materials Project

Tm(O4Cl)3 crystallizes in the hexagonal P6_3/m space group. The structure is three-dimensional. Tm is bonded in a 9-coordinate geometry to nine O atoms. There are six shorter (2.37 Å) and three longer (2.41 Å) Tm–O bond lengths. There are three inequivalent O sites. In the first O site, O is bonded in a single-bond geometry to one Cl atom. The O–Cl bond length is 1.42 Å. In the second O site, O is bonded in a bent 150 degrees geometry to one Tm and one Cl atom. The O–Cl bond length is 1.47 Å. In the third O site, O is bonded in a bent 150 degrees geometry to one Tm and one Cl atom. The O–Cl bond length is 1.47 Å. Cl is bonded in a tetrahedral geometry to four O atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Tm(BRh)4 by Materials Project

TmRh4B4 crystallizes in the tetragonal P4_2/nmc space group. The structure is three-dimensional. Tm is bonded in a 12-coordinate geometry to twelve equivalent Rh and twelve equivalent B atoms. There are four shorter (2.95 Å) and eight longer (3.17 Å) Tm–Rh bond lengths. There are eight shorter (3.02 Å) and four longer (3.16 Å) Tm–B bond lengths. Rh is bonded in a 5-coordinate geometry to three equivalent Tm and five equivalent B atoms. There are two shorter (2.21 Å) and three longer (2.23 Å) Rh–B bond lengths. B is bonded in a 6-coordinate geometry to three equivalent Tm, five equivalent Rh, and one B atom. The B–B bond length is 1.79 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Tm by Materials Project

Tm is Copper structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Tm is bonded to twelve equivalent Tm atoms to form a mixture of face, edge, and corner-sharing TmTm12 cuboctahedra. All Tm–Tm bond lengths are 3.49 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Tm by Materials Project

Tm is Tungsten structured and crystallizes in the cubic Im-3m space group. The structure is three-dimensional. Tm is bonded in a distorted body-centered cubic geometry to eight equivalent Tm atoms. All Tm–Tm bond lengths are 3.41 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Tm by Materials Project

Tm is Magnesium structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Tm is bonded to twelve equivalent Tm atoms to form a mixture of face, edge, and corner-sharing TmTm12 cuboctahedra. There are six shorter (3.44 Å) and six longer (3.56 Å) Tm–Tm bond lengths.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Magnetothermal properties of Tm x Dy 1- x Al 2 ( x = 0.25, 0.50 and 0.75)

Here, we describe magnetic, thermal, and magnetocaloric properties of rare earth intermetallic compounds Tm x Dy 1-x Al 2 with 0.25, 0.5 and 0.75. Using model Hamiltonian we consider contributions of the crystalline electric field anisotropy in both Tm and Dy magnetic sublattices, disorder in exchange interactions among Tm-Tm, Dy-Dy and Tm-Dy magnetic ions, and the Zeeman effect. Employing earlier reported and new experimental measurements, we first determine a single free variable – the intersublattice magnetic exchange parameter – to properly model the temperature and magnetic field dependencies of heat capacity and magnetization, and then use the modeling results to explain the emergence of an anomalous spin reorientation transition and its influence on the magnetocaloric effect in the title compounds. Theoretical results agree with experimental data reasonably well.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Thermodynamics of Tritium Trapping by Point Defects in Intermetallic Al 12 (TM) 2.35 Aluminide Coating Phase

Density functional theory simulations have been carried out to investigate the potential for tritium trapping by metal vacancies in intermetallic Al 12 (TM) 2.35 phase (TM = Fe, Cr, and Ni) as function of temperature and tritium partial pressure. It was found that tritium could be favorably trapped by Fe and Ni vacancies and not favorably trapped by Al and Cr vacancies. However, due to the presence of partially occupied Al sites in bulk Al 12 (TM) 2.35 , leading to the approximate number of ~255 Al atoms in the unit cell, 86 sites were found energetically favorable to the creation of an Al vacancy. While adding a tritium atom in an Al vacancy is not energetically favorable, the tritiated defect still has a negative Gibbs free energy because the energy gain for creating an Al vacancy overcome the energy cost of adding the tritium species. Based on the calculated Gibbs free energy, the first tritiation of a metal vacancy, at conditions relevant to in-reactor operations, should be more favorable for Al, followed Fe, Ni, and Cr vacancies. By comparing the behavior of tritium in Al 12 (TM) 2.35 with previously studied Fe-Al coating phases (i.e., FeNiAl 5 , Fe 4 Al 13 , and Fe 2 Al 5.6 ), we found that there is a correlation between interstitial tritium solubility and the potential for vacancy trapping. The current trend suggests that if the insertion of an interstitial tritium cost more than 0.3 eV, then trapping by metal vacancies should be preferred. By combining the simulations results obtained to date, we noticed different trapping mechanisms of tritium in the Al coating. Tritium is mostly trapped by Fe and Ni vacancies in the outer Fe-Al coating phase Al 12 (TM) 2.35 while tritium should be preferentially trapped by Al and Fe vacancies for the inner Fe-Al coating phases (FeNiAl 5 , Fe 4 Al 13 , Fe 2 Al 5.6 ). Altogether, these studies show that tritium interacts differently with the various Fe-Al aluminide phases, they also suggest that tritium trapping and retention could be more efficient if metal defects are present and if the solubility of interstitial tritium in the different phases is low.

36 MATERIALS SCIENCE↗
NASA NTRS1984

Performance evaluation and geologic utility of LANDSAT-4 TM and MSS data

Radiometric calibration accuracy of TM data, radiometric comparison of A-, B-, and P-format data, and geometric registration accuracy of the TM data at enlarged scales were analyzed. Radiometric analysis of the Wind River Basin, Wyoming scene demonstrates that the TM system can be used to extract image reflectance spectra from ground targets following calibration of the system. It was also demonstrated that: (1) image DN (radiance values) vs. ground reflectance calibration scatterplots yield parameters which can be used to constrain atmospheric models and can determine TM radiometric sensitivity; (2) no significant degradation occurs as a result of radiometric and geometric correction by SCROUNGE processing; and (3) TM data can be enlarged to 1:24000 with no major geometric distortions or misregistration problems to USGS topographic maps.

Paylor, E. D.↗
NASA NTRS1984

Registratiom of TM data to digital elevation models

Several problems arise when attempting to register LANDSAT thematic mapper data to U.S. B Geological Survey digital elevation models (DEMs). The TM data are currently available only in a rotated variant of the Space Oblique Mercator (SOM) map projection. Geometric transforms are thus; required to access TM data in the geodetic coordinates used by the DEMs. Due to positional errors in the TM data, these transforms require some sort of external control. The spatial resolution of TM data exceeds that of the most commonly DEM data. Oversampling DEM data to TM resolution introduces systematic noise. Common terrain processing algorithms (e.g., close computation) compound this problem by acting as high-pass filters.

Source record↗
NASA NTRS1984

Final Comparison of TM and MSS Data for Surface Mine Assessment in Logan County, West Virginia

A variety of classifications during both raw and transformed MSS and TM data sets from 4 September 1982 were performed for the Logan County, West Virginia study area. The object was to compare the utility of TM and MSS data for delineating small, irregular ground features, particularly surface mines, and also to test data reduction/transformation techniques (band selection, canonical analysis, and principal components) in relation to a traditional means of unsupervised classification. Statistical results demonstrate that, on the average, the TM classifications yielded an overall .53 factor of improvement relative to the MSS classifications. When the accuracies for only three minor (in terms of areal extent) land use categories are examined, the factor of improvement for TM over MSS increases to 1.48; i.e., the TM is nearly one and one-half times better than the MSS for delineating small and irregular ground features such as contour strip mines.

Witt, R. G.↗
NASA NTRS1985

Preliminary Comparisons of the Information Content and Utility of TM Versus MSS Data

Some preliminary indications were provided as to the relative merits of actual TM data versus MSS data for land cover mapping related applications. Three analyses were designed which had sensitivity to the differences in spectral, spatial and radiometric parameters between the TM and MSS. In the water body analysis, a primarily spatially related test, the detectability of small uniform targets was examined. The principal components analysis, an examination of the inherent dimensionality of the data, was more spectrally and radiometrically related. The spectral clustering analysis, also heavily spectrally and radiometrically influenced, provided information on the types of targets separable on TM versus MSS data. These analyses were to be conducted with simultaneously collected LANDSAT-4 complete TM (7 band) and MSS (4 band) data. In actuality, 4-band TM data, and archived LANDSAT-2 MSS data of the same area were used.

Markham, B. L.↗
NASA NTRS1985

A First Evaluation of LANDSAT TM Data to Monitor Suspended Sediments in Lakes

The use of LANDSAT to monitor and track changes in the water quality of Lake Chicot, Arizona was assessed using MSS and TM digital data from nine water sites. Results show that: (1) TM Bands 1, 2, 3, and 4 appear to be providing information on concentrations of particulate matter suspended in surface waters. These bands are also highly interrelated for water samples; (2) preliminary evaluation indicates that TM Band 3 showed the best relationship to surface suspended solids; (3) TM Bands 5 and 7 are useful for separating water from nonwater areas; (4) the MSS Bands 2 and 3 can be related to suspended solids in surface water, as has already been shown from previous LANDSAT research; and (5) analysis of TM Band 6 indicates that while synoptic temperature patterns may be discerned, the digital sensitivity to a two degree temperature difference is low.

Schiebe, F. R.↗
NASA NTRS1984

Comparison of classification schemes for MSS and TM data

The launch of the Landsat-4 satellite in July 1982 provided the first full coverage from space of the 0.4-12 micron spectrum of the earth scene. In addition to the green, red, and near IR bands of the MSS, the TM provides a band in the blue, two in the middle IR, and one thermal IR. The paper describes spectral class analysis of coincident MSS and TM data to evaluate the contribution of the additional TM bands. In addition, various classifiers are available which were applied to the TM data. In the spectral class analysis, twice the number of separable classes was found in the TM data compared to the MSS data.

Anuta, P. E.↗
NASA NTRS1985

LANDSAT TM image data quality analysis for energy-related applications

This project represents a no-cost agreement between National Aeronautic Space Administration Goddard Space Flight Center (NASA GSFC) and the Pacific Northwest Laboratory (PNL). PNL is a Department of Energy (DOE) national laboratory operted by Battelle Memorial Institute at its Pacific Northwest Laboratories in Richland, Washington. The objective of this investigation is to evaluate LANDSAT's thematic mapper (TM) data quality and utility characteristics from an energy research and technological perspective. Of main interest is the extent to which repetitive TM data might support DOE efforts relating to siting, developing, and monitoring energy-related facilities, and to basic geoscientific research. The investigation utilizes existing staff and facility capabilities, and ongoing programmatic activities at PNL and other DOE national laboratories to cooperatively assess the potential usefulness of the improved experimental TM data. The investigation involves: (1) both LANDSAT 4 and 5 TM data, (2) qualitative and quantitative use consideration, and 3) NASA P (corrected) and A (uncorrected) CCT analysis for a variety of sites of DOE interest. Initial results were presented at the LANDSAT Investigator's Workshops and at specialized LANDSAT TM sessions at various conferences.

Wukelic, G. E.↗
NASA NTRS1991

Data space volumes and classification optimization of SPOT and Landsat TM data

In order to compare the data space volume of SPOT XS and Landsat TM images, three data sets, i.e., a wetlands/agricultural data set, an agricultural data set, and a forest data set, are examined. The comparisons are made for the same geographic area. The data space volumes for Landsat TM (2, 3, and 4) are found to be 70 to 100 percent larger than the volumes for the SPOT XS images. It is suggested that the additional midinfrared bands contribute to the difference in data space volumes between Landsat TM and SPOT XS. The data space volumes for Landsat TM bands 3, 4, and 5 are more than an order of magnitude greater than the volumes for the three band SPOT XS data sets. The volumes of the six-band Landsat TM images are four orders of magnitude greater than the SPOT XS. The analysis of the data space volumes is used to optimize the computation time and minimize the storage requirements of a maximum-likelihood classification based on a look-up table.

Ahearn, Sean C.↗