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At least 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
NASA NTRS1987

RB-ARD: A proof of concept rule-based abort

The Abort Region Determinator (ARD) is a console program in the space shuttle mission control center. During shuttle ascent, the Flight Dynamics Officer (FDO) uses the ARD to determine the possible abort modes and make abort calls for the crew. The goal of the Rule-based Abort region Determinator (RB/ARD) project was to test the concept of providing an onboard ARD for the shuttle or an automated ARD for the mission control center (MCC). A proof of concept rule-based system was developed on a LMI Lambda computer using PICON, a knowdedge-based system shell. Knowdedge derived from documented flight rules and ARD operation procedures was coded in PICON rules. These rules, in conjunction with modules of conventional code, enable the RB-ARD to carry out key parts of the ARD task. Current capabilities of the RB-ARD include: continuous updating of the available abort mode, recognition of a limited number of main engine faults and recommendation of safing actions. Safing actions recommended by the RB-ARD concern the Space Shuttle Main Engine (SSME) limit shutdown system and powerdown of the SSME Ac buses.

Smith, Richard↗
NASA NTRS1993

Rb-Sr and Sm-Nd isotopic variations in dissected crustal xenoliths

The effect of magma-xenolith interaction on the Rb-Sr and Sm-Nd isotopic systematics was investigated by studying the Rb-Sr and Sm-Nd variations in dissected crustal xenoliths sampled from different localities across Scotland. The Nd isotopic compositions were found to be virtually uniform across each xenolith, but significant variations were found in Rb, Sr, and REE concentrations, as well as in Rb/Sr and Sm/Nd ratios and Sr isotopic composition. Most of these variations appear to be inherited from the protolith, but, in one case, they have been modified by melt infiltration from the host magma. The results lend confidence to the interpretation of the isotopic and chemical compositions of xenoliths transported in basaltic magmas as reflecting their source regions, but they also highlight the potential problems of interpreting Sm-Nd model ages from metamorphic rocks.

Lee, Der-Chuen↗
NASA NTRS1993

Chronology of lunar granite 12033,576: Resetting of Rb-Sr and K-Ca isochrons

Lunar granite 12033,576 is a subsample of the 'large' (approximately 1 g) felsite 12033,507 which was identified from a collection of 4-10 mm particles from the 12033 soil sampled from the north rim of Head Crater in the eastern part of Oceanus Procellarum. Discordant ages of approximately 3.6, approximately 0.8, approximately 3.9, and approximately 2.2 Ga for this lunar granite were obtained, respectively, by the K-Ca, Ar-39/Ar-40, and U-Pb zircon methods in previous studies and by the Rb-Sr method is this study. Assuming the granite crystallized approximately 3.9 Ga ago (zircon age) and was shocked by meteoritic impacts at 0.8 Ga ago (Ar-39-Ar-40 age), the intermediate apparent ages by the Rb-Sr and K-Ca methods can be interpreted as reset by diffusion of the parent and daughter nuclides. The Rb-Sr age is less resistant to resetting than the K-Ca age, but more resistant that the Ar-39/Ar-40 age.

Shih, C.-Y.↗
NASA NTRS2011

Rb-Sr And Sm-Nd Ages, and Petrogenesis of Depleted Shergottite Northwest Africa 5990

Northwest Africa (NWA) 5990 is a very fresh Martian meteorite recently found on Hamada du Draa, Morocco and was classified as an olivine-bearing diabasic igneous rock related to depleted shergottites [1]. The study of [1] also showed that NWA 5990 resembles QUE 94201 in chemical, textural and isotopic aspects, except QUE 94201 contains no olivine. The depleted shergottites are characterized by REE patterns that are highly depleted in LREE, older Sm-Nd ages of 327-575 Ma and highly LREE-depleted sources with Nd= +35~+48 [2-7]. Age-dating these samples by Sm-Nd and Rb-Sr methods is very challenging because they have been strongly shocked and contain very low abundances of light rare earth elements (Sm and Nd), Rb and Sr. In addition, terrestrial contaminants which are commonly present in desert meteorites will compromise the equilibrium of isotopic systems. Since NWA 5990 is a very fresh meteorite, it probably has not been subject to significant desert weathering and thus is a good sample for isotopic studies. In this report, we present Rb-Sr and Sm-Nd isotopic results for NWA 5990, discuss the correlation of the determined ages with those of other depleted shergottites, especially QUE 94201, and discuss the petrogenesis of depleted shergottites.

Shih, C. Y.↗
NASA NTRS2011

K-Ca and Rb-Sr Dating of Lunar Granite 14321 Revisited

K-Ca and Rb-Sr age determinations were made for a bulk feldspar-rich portion of an Apollo rock fragment of the pristine lunar granite clast (14321,1062), an acid-leached split of the sample, and the leachate. K-Ca and Rb-Sr data were also obtained for a whole rock sample of Apollo ferroan anorthosite (FAN, 15415). The recent detection [1] of widespread intermediate composition plagioclase indicates that the generation of a diversity of evolved lunar magmas maybe more common and therefore more important to our understanding of crust formation than previously believed. Our new data strengthen the K-Ca and Rb-Sr internal isochrons of the well-studied Apollo sample 14321 [2], which along with a renewed effort to study evolved lunar magmas will provide an improved understanding of the petrogenetic history of evolved rocks on the Moon.

Simon, Justin I.↗
NASA NTRS2013

NWA 7034 Martian Breccia: Disturbed Rb-Sr Systematics, Preliminary Is Approximately 4.4 Ga Sm-Nd Age

Agee et al. [1] reported a Rb-Sr age of 2.089 [plus or minus] 0.081 Ga for the unique Martian meteoritic breccia NWA 7034 making it the oldest Martian basalt, dating to the early Am-azonian epoch [2] of Martian geologic history. We have attempt-ed to confirm this exciting result. Our new Rb-Sr analyses show the Rb-Sr isotopic system to be disturbed, but preliminary Sm-Nd data suggest an even older age of approximately 4.4 Ga for at least some brec-cia components.

Nyquist, L. E.↗
DOE OSTI2024

Simulating single qubit RB

Single qubit RB is used to measure the error of gates via average gate fidelity. A single qubit RB program was made to calculate this. To filter out potential hardware issues, RB was executed through creating a simulator. Upon simulating both noisy and noise-less gates, we determined that there is a mix of hardware and program issues.

Anguiano, Efren↗
DOE OSTI2020

Materials Data on Rb(InAu2)2 by Materials Project

Rb(Au2In)2 crystallizes in the tetragonal I4/mcm space group. The structure is three-dimensional. Rb1+ is bonded in a 8-coordinate geometry to eight equivalent Au1- atoms. All Rb–Au bond lengths are 3.51 Å. Au1- is bonded in a 10-coordinate geometry to two equivalent Rb1+, four equivalent Au1-, and four equivalent In+1.50+ atoms. There are a spread of Au–Au bond distances ranging from 2.79–3.11 Å. There are a spread of Au–In bond distances ranging from 2.83–3.01 Å. In+1.50+ is bonded in a 8-coordinate geometry to eight equivalent Au1- atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Rb(WO3)6 by Materials Project

Rb(WO3)6 crystallizes in the orthorhombic Pnnm space group. The structure is three-dimensional. Rb1+ is bonded to twelve O2- atoms to form RbO12 cuboctahedra that share edges with twelve WO6 octahedra. All Rb–O bond lengths are 3.36 Å. There are two inequivalent W+5.83+ sites. In the first W+5.83+ site, W+5.83+ is bonded to six O2- atoms to form WO6 octahedra that share corners with six WO6 octahedra and edges with two equivalent RbO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 0–30°. There are a spread of W–O bond distances ranging from 1.92–1.97 Å. In the second W+5.83+ site, W+5.83+ is bonded to six O2- atoms to form WO6 octahedra that share corners with six WO6 octahedra and edges with two equivalent RbO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 0–30°. There are a spread of W–O bond distances ranging from 1.92–1.97 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a linear geometry to two equivalent W+5.83+ atoms. In the second O2- site, O2- is bonded in a bent 150 degrees geometry to one Rb1+ and two W+5.83+ atoms. In the third O2- site, O2- is bonded in a bent 150 degrees geometry to one Rb1+ and two W+5.83+ atoms. In the fourth O2- site, O2- is bonded in a bent 150 degrees geometry to one Rb1+ and two equivalent W+5.83+ atoms. In the fifth O2- site, O2- is bonded in a linear geometry to two equivalent W+5.83+ atoms. In the sixth O2- site, O2- is bonded in a linear geometry to two equivalent W+5.83+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Rb(CoS)2 by Materials Project

Rb(CoS)2 is alpha bismuth trifluoride-derived structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Rb1+ is bonded in a body-centered cubic geometry to eight equivalent S2- atoms. All Rb–S bond lengths are 3.41 Å. Co+1.50+ is bonded to four equivalent S2- atoms to form a mixture of edge and corner-sharing CoS4 tetrahedra. All Co–S bond lengths are 2.22 Å. S2- is bonded in a 8-coordinate geometry to four equivalent Rb1+ and four equivalent Co+1.50+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Rb(WO3)3 by Materials Project

Rb(WO3)3 crystallizes in the hexagonal P6_3/mcm space group. The structure is three-dimensional. Rb1+ is bonded to twelve equivalent O2- atoms to form RbO12 cuboctahedra that share edges with twelve equivalent WO6 octahedra and faces with two equivalent RbO12 cuboctahedra. All Rb–O bond lengths are 3.36 Å. W+5.67+ is bonded to six O2- atoms to form WO6 octahedra that share corners with six equivalent WO6 octahedra and edges with four equivalent RbO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 0–31°. There are a spread of W–O bond distances ranging from 1.94–1.96 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 150 degrees geometry to two equivalent Rb1+ and two equivalent W+5.67+ atoms. In the second O2- site, O2- is bonded in a linear geometry to two equivalent W+5.67+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Rb(CoSe)2 by Materials Project

Rb(CoSe)2 is alpha bismuth trifluoride-derived structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Rb1+ is bonded in a body-centered cubic geometry to eight equivalent Se2- atoms. All Rb–Se bond lengths are 3.52 Å. Co+1.50+ is bonded to four equivalent Se2- atoms to form a mixture of edge and corner-sharing CoSe4 tetrahedra. All Co–Se bond lengths are 2.36 Å. Se2- is bonded in a 8-coordinate geometry to four equivalent Rb1+ and four equivalent Co+1.50+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Rb(WCl3)3 by Materials Project

Rb(WCl3)3 crystallizes in the trigonal P-3 space group. The structure is three-dimensional. Rb1+ is bonded in a 6-coordinate geometry to six equivalent Cl1- atoms. All Rb–Cl bond lengths are 3.50 Å. W+2.67+ is bonded to five Cl1- atoms to form corner-sharing WCl5 square pyramids. There are a spread of W–Cl bond distances ranging from 2.41–2.50 Å. There are three inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a 3-coordinate geometry to two equivalent Rb1+ and one W+2.67+ atom. In the second Cl1- site, Cl1- is bonded in a 2-coordinate geometry to two equivalent W+2.67+ atoms. In the third Cl1- site, Cl1- is bonded in a 2-coordinate geometry to two equivalent W+2.67+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Rb(WO3)6 by Materials Project

Rb(WO3)6 crystallizes in the orthorhombic Pnnm space group. The structure is three-dimensional. Rb1+ is bonded to twelve O2- atoms to form RbO12 cuboctahedra that share edges with twelve WO6 octahedra. All Rb–O bond lengths are 3.36 Å. There are two inequivalent W+5.83+ sites. In the first W+5.83+ site, W+5.83+ is bonded to six O2- atoms to form WO6 octahedra that share corners with six WO6 octahedra and edges with two equivalent RbO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 0–30°. There are a spread of W–O bond distances ranging from 1.92–1.97 Å. In the second W+5.83+ site, W+5.83+ is bonded to six O2- atoms to form WO6 octahedra that share corners with six WO6 octahedra and edges with two equivalent RbO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 0–30°. There are a spread of W–O bond distances ranging from 1.92–1.97 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a linear geometry to two equivalent W+5.83+ atoms. In the second O2- site, O2- is bonded in a bent 150 degrees geometry to one Rb1+ and two W+5.83+ atoms. In the third O2- site, O2- is bonded in a bent 150 degrees geometry to one Rb1+ and two W+5.83+ atoms. In the fourth O2- site, O2- is bonded in a bent 150 degrees geometry to one Rb1+ and two equivalent W+5.83+ atoms. In the fifth O2- site, O2- is bonded in a linear geometry to two equivalent W+5.83+ atoms. In the sixth O2- site, O2- is bonded in a linear geometry to two equivalent W+5.83+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Rb(ThSe3)2 by Materials Project

Rb(ThSe3)2 crystallizes in the orthorhombic Immm space group. The structure is three-dimensional. Rb1+ is bonded to eight equivalent Se+1.50- atoms to form distorted face-sharing RbSe8 hexagonal bipyramids. All Rb–Se bond lengths are 3.59 Å. Th4+ is bonded in a 8-coordinate geometry to eight Se+1.50- atoms. There are a spread of Th–Se bond distances ranging from 2.99–3.02 Å. There are two inequivalent Se+1.50- sites. In the first Se+1.50- site, Se+1.50- is bonded in a 4-coordinate geometry to two equivalent Rb1+, two equivalent Th4+, and two equivalent Se+1.50- atoms. There are one shorter (2.75 Å) and one longer (2.84 Å) Se–Se bond lengths. In the second Se+1.50- site, Se+1.50- is bonded to four equivalent Th4+ atoms to form a mixture of distorted edge and corner-sharing SeTh4 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Rb(SbSe2)2 by Materials Project

Rb(SbSe2)2 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. Rb1+ is bonded in a 9-coordinate geometry to nine Se+1.75- atoms. There are a spread of Rb–Se bond distances ranging from 3.53–4.08 Å. There are two inequivalent Sb3+ sites. In the first Sb3+ site, Sb3+ is bonded to five Se+1.75- atoms to form distorted edge-sharing SbSe5 square pyramids. There are a spread of Sb–Se bond distances ranging from 2.59–3.35 Å. In the second Sb3+ site, Sb3+ is bonded in a see-saw-like geometry to four Se+1.75- atoms. There are a spread of Sb–Se bond distances ranging from 2.62–3.18 Å. There are four inequivalent Se+1.75- sites. In the first Se+1.75- site, Se+1.75- is bonded to one Rb1+ and three Sb3+ atoms to form distorted edge-sharing SeRbSb3 trigonal pyramids. In the second Se+1.75- site, Se+1.75- is bonded in a 5-coordinate geometry to three equivalent Rb1+ and two Sb3+ atoms. In the third Se+1.75- site, Se+1.75- is bonded in a 1-coordinate geometry to three equivalent Rb1+ and one Sb3+ atom. In the fourth Se+1.75- site, Se+1.75- is bonded in a 5-coordinate geometry to two equivalent Rb1+ and three Sb3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Rb(Cr5Te8)3 by Materials Project

Rb(Cr5Te8)3 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. Rb1+ is bonded in a distorted q6 geometry to ten Te2- atoms. There are a spread of Rb–Te bond distances ranging from 3.83–4.06 Å. There are eight inequivalent Cr+3.13+ sites. In the first Cr+3.13+ site, Cr+3.13+ is bonded to six Te2- atoms to form a mixture of edge, face, and corner-sharing CrTe6 octahedra. The corner-sharing octahedra tilt angles range from 50–51°. There are a spread of Cr–Te bond distances ranging from 2.68–2.86 Å. In the second Cr+3.13+ site, Cr+3.13+ is bonded to six Te2- atoms to form a mixture of edge, face, and corner-sharing CrTe6 octahedra. The corner-sharing octahedra tilt angles range from 50–51°. There are a spread of Cr–Te bond distances ranging from 2.68–2.86 Å. In the third Cr+3.13+ site, Cr+3.13+ is bonded to six Te2- atoms to form a mixture of edge, face, and corner-sharing CrTe6 octahedra. The corner-sharing octahedra tilt angles range from 50–51°. There are a spread of Cr–Te bond distances ranging from 2.68–2.86 Å. In the fourth Cr+3.13+ site, Cr+3.13+ is bonded to six Te2- atoms to form a mixture of edge, face, and corner-sharing CrTe6 octahedra. The corner-sharing octahedra tilt angles range from 49–51°. There are a spread of Cr–Te bond distances ranging from 2.70–2.83 Å. In the fifth Cr+3.13+ site, Cr+3.13+ is bonded to six Te2- atoms to form a mixture of edge, face, and corner-sharing CrTe6 octahedra. The corner-sharing octahedra tilt angles range from 49–51°. There are a spread of Cr–Te bond distances ranging from 2.68–2.81 Å. In the sixth Cr+3.13+ site, Cr+3.13+ is bonded to six Te2- atoms to form a mixture of edge, face, and corner-sharing CrTe6 octahedra. The corner-sharing octahedra tilt angles range from 49–51°. There are a spread of Cr–Te bond distances ranging from 2.69–2.82 Å. In the seventh Cr+3.13+ site, Cr+3.13+ is bonded to six Te2- atoms to form a mixture of edge and corner-sharing CrTe6 octahedra. The corner-sharing octahedral tilt angles are 49°. There are a spread of Cr–Te bond distances ranging from 2.73–2.75 Å. In the eighth Cr+3.13+ site, Cr+3.13+ is bonded to six Te2- atoms to form a mixture of edge and corner-sharing CrTe6 octahedra. The corner-sharing octahedral tilt angles are 49°. There are two shorter (2.73 Å) and four longer (2.74 Å) Cr–Te bond lengths. There are twelve inequivalent Te2- sites. In the first Te2- site, Te2- is bonded in a rectangular see-saw-like geometry to four Cr+3.13+ atoms. In the second Te2- site, Te2- is bonded in a 4-coordinate geometry to one Rb1+ and four Cr+3.13+ atoms. In the third Te2- site, Te2- is bonded in a rectangular see-saw-like geometry to four Cr+3.13+ atoms. In the fourth Te2- site, Te2- is bonded in a 5-coordinate geometry to five Cr+3.13+ atoms. In the fifth Te2- site, Te2- is bonded in a 5-coordinate geometry to five Cr+3.13+ atoms. In the sixth Te2- site, Te2- is bonded in a 5-coordinate geometry to five Cr+3.13+ atoms. In the seventh Te2- site, Te2- is bonded in a 4-coordinate geometry to one Rb1+ and three Cr+3.13+ atoms. In the eighth Te2- site, Te2- is bonded in a 4-coordinate geometry to one Rb1+ and three Cr+3.13+ atoms. In the ninth Te2- site, Te2- is bonded in a 3-coordinate geometry to three Cr+3.13+ atoms. In the tenth Te2- site, Te2- is bonded in a distorted rectangular see-saw-like geometry to one Rb1+ and three Cr+3.13+ atoms. In the eleventh Te2- site, Te2- is bonded in a 3-coordinate geometry to three Cr+3.13+ atoms. In the twelfth Te2- site, Te2- is bonded in a distorted rectangular see-saw-like geometry to one Rb1+ and three Cr+3.13+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Rb(SiPt)4 by Materials Project

Rb(PtSi)4 crystallizes in the tetragonal I4 space group. The structure is three-dimensional. Rb1+ is bonded in a 8-coordinate geometry to eight equivalent Pt+0.25- atoms. There are four shorter (3.31 Å) and four longer (3.44 Å) Rb–Pt bond lengths. Pt+0.25- is bonded in a 5-coordinate geometry to two equivalent Rb1+ and five equivalent Si atoms. There are a spread of Pt–Si bond distances ranging from 2.42–2.57 Å. Si is bonded in a 5-coordinate geometry to five equivalent Pt+0.25- atoms.

36 MATERIALS SCIENCE↗