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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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6 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1974

Stability properties of functional difference equations

Hale and Cruz (1970) have defined the concept of a stable difference operator, and have found that this class of operators is sometimes 'super sensitive' to perturbations. In the present paper, a subclass of general functional difference equations is derived which retain their stability under appropriate perturbations. Also, the results of Hale and Cruz are extended to include difference equations on the Banach space of p-th power integrable functions, and essentially bounded functions.

Melvin, W. R.↗
NASA NTRS1979

Extreme Mean and Its Applications

Extreme value statistics obtained from normally distributed data are considered. An extreme mean is defined as the mean of p-th probability truncated normal distribution. An unbiased estimate of this extreme mean and its large sample distribution are derived. The distribution of this estimate even for very large samples is found to be nonnormal. Further, as the sample size increases, the variance of the unbiased estimate converges to the Cramer-Rao lower bound. The computer program used to obtain the density and distribution functions of the standardized unbiased estimate, and the confidence intervals of the extreme mean for any data are included for ready application. An example is included to demonstrate the usefulness of extreme mean application.

Swaroop, R.↗
DOE OSTI2020

Materials Data on Th3P4 by Materials Project

Th3P4 crystallizes in the cubic I-43d space group. The structure is three-dimensional. Th4+ is bonded to eight equivalent P3- atoms to form a mixture of distorted edge, corner, and face-sharing ThP8 hexagonal bipyramids. There are four shorter (2.95 Å) and four longer (3.03 Å) Th–P bond lengths. P3- is bonded to six equivalent Th4+ atoms to form a mixture of distorted edge, corner, and face-sharing PTh6 octahedra. The corner-sharing octahedra tilt angles range from 15–51°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on ThP7 by Materials Project

ThP7 crystallizes in the orthorhombic P2_12_12_1 space group. The structure is three-dimensional. Th4+ is bonded in a 10-coordinate geometry to ten P+0.57- atoms. There are a spread of Th–P bond distances ranging from 2.94–3.20 Å. There are seven inequivalent P+0.57- sites. In the first P+0.57- site, P+0.57- is bonded in a 5-coordinate geometry to one Th4+ and two P+0.57- atoms. There are one shorter (2.23 Å) and one longer (2.26 Å) P–P bond lengths. In the second P+0.57- site, P+0.57- is bonded to two equivalent Th4+ and two P+0.57- atoms to form distorted PTh2P2 trigonal pyramids that share corners with seven PThP3 tetrahedra, corners with five PTh2P2 trigonal pyramids, an edgeedge with one PThP3 tetrahedra, and an edgeedge with one PTh2P2 trigonal pyramid. There are one shorter (2.20 Å) and one longer (2.26 Å) P–P bond lengths. In the third P+0.57- site, P+0.57- is bonded to one Th4+ and three P+0.57- atoms to form PThP3 tetrahedra that share corners with five PThP3 tetrahedra and corners with four PTh2P2 trigonal pyramids. The P–P bond length is 2.22 Å. In the fourth P+0.57- site, P+0.57- is bonded in a 3-coordinate geometry to one Th4+ and two P+0.57- atoms. The P–P bond length is 2.23 Å. In the fifth P+0.57- site, P+0.57- is bonded to two equivalent Th4+ and two P+0.57- atoms to form distorted PTh2P2 trigonal pyramids that share corners with seven PThP3 tetrahedra, corners with five PTh2P2 trigonal pyramids, an edgeedge with one PTh2P2 tetrahedra, and an edgeedge with one PTh2P2 trigonal pyramid. The P–P bond length is 2.22 Å. In the sixth P+0.57- site, P+0.57- is bonded to one Th4+ and three P+0.57- atoms to form PThP3 tetrahedra that share corners with four PThP3 tetrahedra, corners with three PTh2P2 trigonal pyramids, and an edgeedge with one PTh2P2 trigonal pyramid. The P–P bond length is 2.24 Å. In the seventh P+0.57- site, P+0.57- is bonded to two equivalent Th4+ and two P+0.57- atoms to form PTh2P2 tetrahedra that share corners with seven PThP3 tetrahedra, corners with seven PTh2P2 trigonal pyramids, and an edgeedge with one PTh2P2 trigonal pyramid.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on ThP by Materials Project

PTh is Halite, Rock Salt structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Th is bonded to six equivalent P atoms to form a mixture of corner and edge-sharing ThP6 octahedra. The corner-sharing octahedral tilt angles are 0°. All Th–P bond lengths are 2.93 Å. P is bonded to six equivalent Th atoms to form a mixture of corner and edge-sharing PTh6 octahedra. The corner-sharing octahedral tilt angles are 0°.

36 MATERIALS SCIENCE↗