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DOE OSTI2020

Materials Data on ThSe(IO7)2 by Materials Project

ThSe(O7I)2 crystallizes in the monoclinic P2_1/c space group. The structure is two-dimensional and consists of one ThSe(O7I)2 sheet oriented in the (1, 0, 0) direction. Th is bonded in a 7-coordinate geometry to seven O atoms. There are a spread of Th–O bond distances ranging from 2.27–2.71 Å. Se is bonded in a tetrahedral geometry to four O atoms. There are a spread of Se–O bond distances ranging from 1.62–1.72 Å. There are fourteen inequivalent O sites. In the first O site, O is bonded in a bent 120 degrees geometry to one Th and one I atom. The O–I bond length is 1.88 Å. In the second O site, O is bonded in a single-bond geometry to one O atom. The O–O bond length is 1.27 Å. In the third O site, O is bonded in a single-bond geometry to one I atom. The O–I bond length is 1.78 Å. In the fourth O site, O is bonded in a single-bond geometry to one I atom. The O–I bond length is 1.77 Å. In the fifth O site, O is bonded in a bent 150 degrees geometry to one Th and one Se atom. In the sixth O site, O is bonded in a bent 150 degrees geometry to one Th and one Se atom. In the seventh O site, O is bonded in a bent 120 degrees geometry to two O atoms. The O–O bond length is 1.31 Å. In the eighth O site, O is bonded in a distorted bent 120 degrees geometry to one Th and one I atom. The O–I bond length is 1.83 Å. In the ninth O site, O is bonded in a single-bond geometry to one Se atom. In the tenth O site, O is bonded in a bent 150 degrees geometry to one Th and one I atom. The O–I bond length is 1.81 Å. In the eleventh O site, O is bonded in a distorted single-bond geometry to one Se and one I atom. The O–I bond length is 2.55 Å. In the twelfth O site, O is bonded in a single-bond geometry to one I atom. The O–I bond length is 1.79 Å. In the thirteenth O site, O is bonded in a water-like geometry to one Th and one O atom. In the fourteenth O site, O is bonded in a bent 150 degrees geometry to one Th and one I atom. The O–I bond length is 1.89 Å. There are two inequivalent I sites. In the first I site, I is bonded in a tetrahedral geometry to four O atoms. In the second I site, I is bonded in a 4-coordinate geometry to four O atoms.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on ThSe by Materials Project

ThSe 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 Se atoms to form a mixture of edge and corner-sharing ThSe6 octahedra. The corner-sharing octahedral tilt angles are 0°. All Th–Se bond lengths are 2.97 Å. Se is bonded to six equivalent Th atoms to form a mixture of edge and corner-sharing SeTh6 octahedra. The corner-sharing octahedral tilt angles are 0°.

36 MATERIALS SCIENCE↗

NASA NTRS1982

A search for spectroscopic binaries among the runaway O type stars

Numerous radial velocity measurements of medium dispersion were made for the 10 brighter stars given in Stone's list of very probable O type runaways. All plates were measured with the KPNO PDS microdensitometer, and a new iterative reductional analysis was used to derive plate velocities, which are estimated to be 1.6 times more accurate internally than those found by using the traditional method. Of thse stars, psi Per, alpha Cam, HD 188209, and 26 Cep are identified as probable velocity variables, while 9 Sge, lambda Cep, and HD 218915 are classed as possible variables. If the source of this variability is Keplerian rather than atmospheric, which cannot be established unequivocally from the observations of this paper, psi Per could be a spectroscopic binary with a black hole companion, and at least 1.2 solar mass. The detection of runaway binary systems from radial velocity measurements is discussed.

Stone, R. C.↗

NASA NTRS1983

Space shuttle orbiter leading-edge flight performance compared to design goals

Thermo-structural performance of the Space Shuttle orbiter Columbia's leading-edge structural subsystem for the first five (5) flights is compared with the design goals. Lessons learned from thse initial flights of the first reusable manned spacecraft are discussed in order to assess design maturity, deficiencies, and modifications required to rectify the design deficiencies. Flight data and post-flight inspections support the conclusion that the leading-edge structural subsystem hardware performance was outstanding for the initial five (5) flights.

Curry, D. M.↗

NASA NTRS1985

Cosmogenic Mn-53 in meteorites

The distributions of the Mn-53 contents in 106 nonantarctic and 112 antarctic chondrites were analyzed. A correlation analysis of these distributions showed that the correlation coefficient is a maximum r sub max = 0.75 plus or minus 0.03) when the histogram for antarctic chondrites is displaced by 40 plus or minus 8 dpm kg-1Fe towards lower Mn-53 contents. The distribution of Mn-53 saturated contents in nonantarctic ordinary chondrites was investigated as a function of their radiation age (T). It is found that the Mn-53 average content is higher by (21 plus or minus 9)% in H-chondrites with radiation age T approximately 12 Myr than in thse with T 12 Myr. This effect can be attributed to the fact that a considerable proportion of H-chondrites with T 12 Myr originates from a comet or from the objects of Chiron like, with the orbits more inclined to the ecliptic plane and/or more extended, which caused their irradiation by cosmic rays of higher intensity.

Alexeev, V. A.↗

NASA NTRS1986

Fatigue crack growth under general-yielding cyclic-loading

In low cycle fatigue, cracks are initiated and propagated under general yielding cyclic loading. For general yielding cyclic loading, Dowling and Begley have shown that fatigue crack growth rate correlates well with the measured delta J. The correlation of da/dN with delta J was also studied by a number of other investigators. However, none of thse studies have correlated da/dN with delta J calculated specifically for the test specimens. Solomon measured fatigue crack growth in specimens in general yielding cyclic loading. The crack tips fields for Solomon's specimens are calculated using the finite element method and the J values of Solomon's tests are evaluated. The measured crack growth rate in Solomon's specimens correlates very well with the calculated delta J.

Minzhong, Z.↗

NASA NTRS1991

Galileo Attitude Determination: Experiences with a Rotating Star Scanner

The Galileo experience with a rotating star scanner is discussed in terms of problems encountered in flight, solutions implemented, and lessons learned. An overview of the Galileo project and the attitude and articulation control subsystem is given and the star scanner hardware and relevant software algorithms are detailed. The star scanner is the sole source of inertial attitude reference for this spacecraft. Problem symptoms observed in flight are discussed in terms of effects on spacecraft performance and safety. Sources of thse problems include contributions from flight software idiosyncrasies and inadequate validation of the ground procedures used to identify target stars for use by the autonomous on-board star identification algorithm. Problem fixes (some already implemented and some only proposed) are discussed. A general conclusion is drawn regarding the inherent difficulty of performing simulation tests to validate algorithms which are highly sensitive to external inputs of statistically 'rare' events.

Merken, L.↗

NASA NTRS1991

Constraints on the origin of the ultraviolet upturn in elliptical galaxies from Hopkins Ultraviolet Telescope observations of NGC 1399

Results are presented of observations of the giant elliptical galaxy NGC 1399 in December 1990, which provide measurements of the spectral energy distribution of the elliptical galaxy and allow detection of absorption features in the sub-2000-A UV. The spectrum shows no emission features other than well-known geocoronal lines. Strong Lyman series absorption is evident at the galaxy redshift. Other absorption features attributable to the hot stellar population are detected, but there is no evidence of C IV 1548, 1551 absorption. Thse data are used to set constraints on the origin of the UV upturn in elliptical galaxies. The lack of detectable C IV absorption and the shape of the continuum spectrum exclude star formation with a standard IMF as the sole contributor to the 1550-A flux. The observed continuum flux decreases from 1050 A to the Lyman limit, indicating that the light is dominated by stars with temperatures less than 25,000 K. For star-formation models, this temperature puts the main-sequence turnoff near B0, implying either that star formation ended about 2 x 10 exp 7 yr ago, or that stars are currently forming with a truncated IMF.

Ferguson, Henry C.↗

NASA NTRS2005

A membrane array using T/R membranes

We have developed the first membrane-compatible Trasmit/Receive (T/R) module (T/R membrane). Using thse modules we developed a membrane-basede active phased array in L-band. We use phase shifters within each T/R module for electronic beam stering. In this paper we will discuss the T/R membrane design and integration with the membrane.

T/R module↗

NASA NTRS2003

Sea ice investigations from Seasat to the present

In this paper, we provide a short review of sea ice investigations starting from Seasat. We focus particularly on the detailed and quantitative measurements of the sea ice motion field, which were some of the earliest results from Seasat and have sugsequently been shown to be of critical value to the derivation of several key climatically important variables. Other key investigations discussed include examination of the seasonal melt cycle, ice extent and concentration, and estimates of thickness from the proxy measurements of ice type and age and more directly from freeboard. We end with a brief discussion on how thse measurements might be improved in the future.

sea ice↗

NASA NTRS2003

The case for applying an early-lifecycle technology evaluation methodology to comparative evaluation of requirements engineering research

The premise of this paper is taht there is a useful analogy between evaluation of proposed problem solutions and evaluation of requirements engineering research itself. Both of these application areas face the challenges of evaluation early in the lifecycle, of the need to consider a wide variety of factors, and of the need to combine inputs from multiple stakeholders in making thse evaluation and subsequent decisions.

technology transfer↗

NASA NTRS1989

Ethynyl terminated imidothioethers and resins therefrom

Ethynyl terminated imidothioethers (ETIs) are prepared by the reaction of a dimercaptan, such as 4,4'-dimercaptodiphenyl ether, and an ethynyl containing maleimide, such as N-(3-ethynylphenyl)maleimide. Blends of thse ETIs and ethynyl terminated polymeric materials, such as ethynyl terminated sulfones and ethynyl terminated arylene ethers, are also prepared. These resin blends exhibit excellent processability, and the cured blends show excellent fracture toughness and solvent resistance, as well as excellent adhesive and composite properties.

Hergenrother, Paul M.↗