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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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At least 757 records · Page 42
All sourcesNASA NTRSDOE OSTI
NASA NTRS1993

A diminished aortic-cardiac reflex during hypotension in aerobically fit young men

We compared the aortic-cardiac baroreflex sensitivity in eight average fit (AF: VO2max = 44.7 +/- 1.3 ml.kg-1 x min-1) and seven high fit (HF: VO2max = 64.1 +/- 1.7 ml.min-1 x kg-1) healthy young men during hypotension elicited by steady state sodium nitroprusside (SN) infusion. During SN mean arterial pressure (MAP) was similarly decreased in AF (-12.6 +/- 1.0 mm Hg) and HF (-12.1 +/- 1.1 mm Hg). However, the increases in heart rate (HR) were less (P < 0.023) in HF (15 +/- 3 bpm) than AF (25 +/- 1 bpm). When sustained neck suction (NS, -22 +/- 1 torr in AF and -20 +/- 1 torr in HF, P > 0.05) was applied to counteract the decreased carotid sinus transmural pressure during SN, thereby isolating the aortic baroreceptors, the increased HR remained less (P < 0.021) in HF (8 +/- 2 bpm) than AF (16 +/- 2 bpm). During both SN infusion and SN+NS, the calculated gains (i.e., delta HR/delta MAP) were significantly greater in AF (2.1 +/- 0.3 and 1.3 +/- 0.2 bpm.mm Hg-1) than HF (1.2 +/- 0.2 and 0.6 +/- 0.2 bpm.mm Hg-1). However, the estimated carotid-cardiac baroreflex sensitivity (i.e., the gain difference between the stage SN and SN + NS) was not different between AF (0.7 +/- 0.2 bpm.mm Hg-1) and HF (0.6 +/- 0.1 bpm.mm Hg-1). These data indicated that the aortic-cardiac baroreflex sensitivity during hypotension was significantly diminished with endurance exercise training.

NASA Discipline Number 14-10↗
NASA NTRS2013

Empirical Study of the Multiaxial, Thermomechanical Behavior of NiTiHf Shape Memory Alloys

An empirical study was conducted to characterize the multiaxial, thermomechanical responses of new high temperature NiTiHf alloys. The experimentation included loading thin walled tube Ni(sub 50.3)Ti(sub 29.7)Hf(sub 20) alloy samples along both proportional and nonproportional axial-torsion paths at different temperatures while measuring surface strains using stereo digital image correlation. A Ni(sub 50.3)Ti(sub 33.7)Hf(sub 16) alloy was also studied in tension and compression to document the effect of slightly depleting the Hf content on the constitutive responses of NiTiHf alloys. Samples of both alloys were made from nearly texture free polycrystalline material processed by hot extrusion. Analysis of the data shows that very small changes in composition significantly alter NiTiHf alloy properties, as the austenite finish (Af) temperature of the 16-at Hf alloy was found to be approximately 60 C less than the 20-at Hf alloy (approximately 120 C vs. 180 C). In addition, the 16-at Hf alloy exhibited smaller compressive transformation strains (2 vs. 2.5 percent). Multi-axial characterization of the 20-at % Hf alloy showed that while the random polycrystal transformation strains in tension (4 percent) and compression (2.5 percent) are modest in comparison with binary NiTi (6 percent, 4 percent), the torsion performance is superior (7 vs. 4 shear strain width to the pseudoelastic plateau).

tensile deformation↗
NASA NTRS2016

Human Factors Checklist: Think Human Factors - Focus on the People

A quick-look Human Factors (HF) Checklist condenses industry and NASA Agency standards consisting of thousands of requirements into 14 main categories. With support from contractor HF and Safety Practitioners, NASA developed a means to share key HF messages with Design, Engineering, Safety, Project Management, and others. It is often difficult to complete timely assessments due to the large volume of HF information. The HF Checklist evolved over time into a simple way to consider the most important concepts. A wide audience can apply the checklist early in design or through planning phases, even before hardware or processes are finalized or implemented. The checklist is a good place to start to supplement formal HF evaluation. The HF Checklist was based on many Space Shuttle processing experiences and lessons learned. It is now being applied to ground processing of new space vehicles and adjusted for new facilities and systems.

Human Factors; Human Systems Integration↗
DOE OSTI2020

Materials Data on Hf3(Cu2Ge)2 by Materials Project

Hf3(Cu2Ge)2 crystallizes in the hexagonal P-62m space group. The structure is three-dimensional. Hf is bonded in a 5-coordinate geometry to seven Cu and four equivalent Ge atoms. There are a spread of Hf–Cu bond distances ranging from 2.63–3.04 Å. All Hf–Ge bond lengths are 2.78 Å. There are two inequivalent Cu sites. In the first Cu site, Cu is bonded in a distorted trigonal planar geometry to three equivalent Hf and six equivalent Cu atoms. All Cu–Cu bond lengths are 2.52 Å. In the second Cu site, Cu is bonded to six equivalent Hf, four Cu, and two equivalent Ge atoms to form a mixture of distorted corner, edge, and face-sharing CuHf6Cu4Ge2 cuboctahedra. Both Cu–Cu bond lengths are 2.66 Å. Both Cu–Ge bond lengths are 2.48 Å. Ge is bonded in a 9-coordinate geometry to six equivalent Hf and three equivalent Cu atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Hf2Al by Materials Project

Hf2Al is Khatyrkite structured and crystallizes in the tetragonal I4/mcm space group. The structure is three-dimensional. Hf is bonded in a 4-coordinate geometry to one Hf and four equivalent Al atoms. The Hf–Hf bond length is 2.93 Å. All Hf–Al bond lengths are 2.91 Å. Al is bonded in a 10-coordinate geometry to eight equivalent Hf and two equivalent Al atoms. Both Al–Al bond lengths are 2.61 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on HfPRu by Materials Project

HfRuP crystallizes in the hexagonal P-62m space group. The structure is three-dimensional. Hf is bonded in a 11-coordinate geometry to six equivalent Ru and five P atoms. There are two shorter (2.88 Å) and four longer (3.01 Å) Hf–Ru bond lengths. There are one shorter (2.68 Å) and four longer (2.71 Å) Hf–P bond lengths. Ru is bonded to six equivalent Hf, two equivalent Ru, and four P atoms to form a mixture of distorted corner, edge, and face-sharing RuHf6P4Ru2 cuboctahedra. Both Ru–Ru bond lengths are 2.75 Å. All Ru–P bond lengths are 2.47 Å. There are two inequivalent P sites. In the first P site, P is bonded in a 9-coordinate geometry to six equivalent Hf and three equivalent Ru atoms. In the second P site, P is bonded in a 9-coordinate geometry to three equivalent Hf and six equivalent Ru atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Hf3(Cu2Si)2 by Materials Project

Hf3(Cu2Si)2 crystallizes in the hexagonal P-62m space group. The structure is three-dimensional. Hf is bonded in a 5-coordinate geometry to seven Cu and four equivalent Si atoms. There are a spread of Hf–Cu bond distances ranging from 2.61–3.02 Å. All Hf–Si bond lengths are 2.75 Å. There are two inequivalent Cu sites. In the first Cu site, Cu is bonded to six equivalent Hf, four Cu, and two equivalent Si atoms to form a mixture of distorted corner, edge, and face-sharing CuHf6Cu4Si2 cuboctahedra. There are two shorter (2.53 Å) and two longer (2.71 Å) Cu–Cu bond lengths. Both Cu–Si bond lengths are 2.42 Å. In the second Cu site, Cu is bonded in a distorted trigonal planar geometry to three equivalent Hf and six equivalent Cu atoms. Si is bonded in a 9-coordinate geometry to six equivalent Hf and three equivalent Cu atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on HfGaPd by Materials Project

HfPdGa crystallizes in the hexagonal P-62c space group. The structure is three-dimensional. Hf is bonded in a 11-coordinate geometry to five Pd and six equivalent Ga atoms. There are a spread of Hf–Pd bond distances ranging from 2.78–2.87 Å. There are a spread of Hf–Ga bond distances ranging from 2.97–3.14 Å. There are two inequivalent Pd sites. In the first Pd site, Pd is bonded in a 9-coordinate geometry to six equivalent Hf and three equivalent Ga atoms. All Pd–Ga bond lengths are 2.67 Å. In the second Pd site, Pd is bonded in a 9-coordinate geometry to three equivalent Hf and six equivalent Ga atoms. All Pd–Ga bond lengths are 2.60 Å. Ga is bonded in a 10-coordinate geometry to six equivalent Hf and four Pd atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on HfCuSi2 by Materials Project

HfCuSi2 crystallizes in the tetragonal P4/nmm space group. The structure is three-dimensional. Hf is bonded to four equivalent Cu and eight Si atoms to form distorted HfCu4Si8 cuboctahedra that share corners with four equivalent HfCu4Si8 cuboctahedra, edges with eight equivalent HfCu4Si8 cuboctahedra, edges with eight equivalent CuHf4Cu4Si4 cuboctahedra, faces with four equivalent HfCu4Si8 cuboctahedra, and faces with four equivalent CuHf4Cu4Si4 cuboctahedra. All Hf–Cu bond lengths are 3.02 Å. There are four shorter (2.73 Å) and four longer (2.79 Å) Hf–Si bond lengths. Cu is bonded to four equivalent Hf, four equivalent Cu, and four equivalent Si atoms to form CuHf4Cu4Si4 cuboctahedra that share corners with four equivalent CuHf4Cu4Si4 cuboctahedra, edges with eight equivalent HfCu4Si8 cuboctahedra, faces with four equivalent HfCu4Si8 cuboctahedra, and faces with eight equivalent CuHf4Cu4Si4 cuboctahedra. All Cu–Cu bond lengths are 2.61 Å. All Cu–Si bond lengths are 2.42 Å. There are two inequivalent Si sites. In the first Si site, Si is bonded in a 8-coordinate geometry to four equivalent Hf and four equivalent Si atoms. All Si–Si bond lengths are 2.61 Å. In the second Si site, Si is bonded in a 4-coordinate geometry to four equivalent Hf and four equivalent Cu atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on HfFeGe by Materials Project

HfFeGe crystallizes in the hexagonal P-62m space group. The structure is three-dimensional. Hf is bonded in a 11-coordinate geometry to six equivalent Fe and five Ge atoms. There are two shorter (2.91 Å) and four longer (3.01 Å) Hf–Fe bond lengths. There are four shorter (2.71 Å) and one longer (2.72 Å) Hf–Ge bond lengths. Fe is bonded in a 12-coordinate geometry to six equivalent Hf, two equivalent Fe, and four Ge atoms. Both Fe–Fe bond lengths are 2.71 Å. There are two shorter (2.43 Å) and two longer (2.54 Å) Fe–Ge bond lengths. There are two inequivalent Ge sites. In the first Ge site, Ge is bonded in a distorted q6 geometry to three equivalent Hf and six equivalent Fe atoms. In the second Ge site, Ge is bonded in a 9-coordinate geometry to six equivalent Hf and three equivalent Fe atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on HfCoSn by Materials Project

HfCoSn crystallizes in the hexagonal P-62c space group. The structure is three-dimensional. Hf is bonded in a 11-coordinate geometry to five Co and six equivalent Sn atoms. There are a spread of Hf–Co bond distances ranging from 2.71–2.95 Å. There are a spread of Hf–Sn bond distances ranging from 2.98–3.10 Å. There are two inequivalent Co sites. In the first Co site, Co is bonded in a 9-coordinate geometry to three equivalent Hf and six equivalent Sn atoms. All Co–Sn bond lengths are 2.61 Å. In the second Co site, Co is bonded in a 9-coordinate geometry to six equivalent Hf and three equivalent Sn atoms. All Co–Sn bond lengths are 2.65 Å. Sn is bonded in a 10-coordinate geometry to six equivalent Hf and four Co atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on HfSnRh by Materials Project

HfRhSn crystallizes in the hexagonal P-62c space group. The structure is three-dimensional. Hf is bonded in a 11-coordinate geometry to five Rh and six equivalent Sn atoms. There are a spread of Hf–Rh bond distances ranging from 2.83–2.99 Å. There are a spread of Hf–Sn bond distances ranging from 3.05–3.23 Å. There are two inequivalent Rh sites. In the first Rh site, Rh is bonded in a 9-coordinate geometry to six equivalent Hf and three equivalent Sn atoms. All Rh–Sn bond lengths are 2.74 Å. In the second Rh site, Rh is bonded in a 9-coordinate geometry to three equivalent Hf and six equivalent Sn atoms. All Rh–Sn bond lengths are 2.70 Å. Sn is bonded in a 10-coordinate geometry to six equivalent Hf and four Rh atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on HfCuHg2 by Materials Project

HfCuHg2 crystallizes in the cubic F-43m space group. The structure is three-dimensional. Hf is bonded in a distorted body-centered cubic geometry to four equivalent Cu and ten Hg atoms. All Hf–Cu bond lengths are 2.91 Å. There are four shorter (2.91 Å) and six longer (3.36 Å) Hf–Hg bond lengths. Cu is bonded in a body-centered cubic geometry to four equivalent Hf and four equivalent Hg atoms. All Cu–Hg bond lengths are 2.91 Å. There are two inequivalent Hg sites. In the first Hg site, Hg is bonded to four equivalent Hf and four equivalent Hg atoms to form distorted edge-sharing HgHf4Hg4 tetrahedra. All Hg–Hg bond lengths are 2.91 Å. In the second Hg site, Hg is bonded in a 4-coordinate geometry to six equivalent Hf, four equivalent Cu, and four equivalent Hg atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on HfZn2 by Materials Project

HfZn2 is Cubic Laves structured and crystallizes in the cubic Fd-3m space group. The structure is three-dimensional. Hf is bonded in a 12-coordinate geometry to four equivalent Hf and twelve equivalent Zn atoms. All Hf–Hf bond lengths are 3.19 Å. All Hf–Zn bond lengths are 3.05 Å. Zn is bonded to six equivalent Hf and six equivalent Zn atoms to form a mixture of edge, face, and corner-sharing ZnHf6Zn6 cuboctahedra. All Zn–Zn bond lengths are 2.60 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on HfGaPt by Materials Project

HfPtGa crystallizes in the hexagonal P-62c space group. The structure is three-dimensional. Hf is bonded in a 11-coordinate geometry to five Pt and six equivalent Ga atoms. There are a spread of Hf–Pt bond distances ranging from 2.80–2.87 Å. There are a spread of Hf–Ga bond distances ranging from 2.98–3.16 Å. There are two inequivalent Pt sites. In the first Pt site, Pt is bonded in a 9-coordinate geometry to six equivalent Hf and three equivalent Ga atoms. All Pt–Ga bond lengths are 2.67 Å. In the second Pt site, Pt is bonded in a 9-coordinate geometry to three equivalent Hf and six equivalent Ga atoms. All Pt–Ga bond lengths are 2.61 Å. Ga is bonded in a 10-coordinate geometry to six equivalent Hf and four Pt atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on HfAlPt by Materials Project

HfPtAl crystallizes in the hexagonal P-62c space group. The structure is three-dimensional. Hf is bonded in a 5-coordinate geometry to five Pt and six equivalent Al atoms. There are a spread of Hf–Pt bond distances ranging from 2.79–2.88 Å. There are a spread of Hf–Al bond distances ranging from 3.01–3.18 Å. There are two inequivalent Pt sites. In the first Pt site, Pt is bonded in a 9-coordinate geometry to three equivalent Hf and six equivalent Al atoms. All Pt–Al bond lengths are 2.58 Å. In the second Pt site, Pt is bonded in a 9-coordinate geometry to six equivalent Hf and three equivalent Al atoms. All Pt–Al bond lengths are 2.67 Å. Al is bonded in a 4-coordinate geometry to six equivalent Hf and four Pt atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Hf6Ni16Ge7 by Materials Project

Hf6Ni16Ge7 crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Hf is bonded in a 12-coordinate geometry to eight Ni and four equivalent Ge atoms. There are four shorter (2.78 Å) and four longer (2.82 Å) Hf–Ni bond lengths. All Hf–Ge bond lengths are 2.95 Å. There are two inequivalent Ni sites. In the first Ni site, Ni is bonded in a 7-coordinate geometry to three equivalent Hf, six Ni, and four Ge atoms. There are three shorter (2.61 Å) and three longer (2.75 Å) Ni–Ni bond lengths. There are one shorter (2.38 Å) and three longer (2.56 Å) Ni–Ge bond lengths. In the second Ni site, Ni is bonded in a 12-coordinate geometry to three equivalent Hf, three equivalent Ni, and three equivalent Ge atoms. All Ni–Ge bond lengths are 2.37 Å. There are two inequivalent Ge sites. In the first Ge site, Ge is bonded in a body-centered cubic geometry to eight equivalent Ni atoms. In the second Ge site, Ge is bonded to four equivalent Hf and eight Ni atoms to form a mixture of corner and face-sharing GeHf4Ni8 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Hf6Si7Ni16 by Materials Project

Ni16Hf6Si7 crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Hf is bonded in a 12-coordinate geometry to eight Ni and four equivalent Si atoms. There are four shorter (2.74 Å) and four longer (2.77 Å) Hf–Ni bond lengths. All Hf–Si bond lengths are 2.90 Å. There are two inequivalent Ni sites. In the first Ni site, Ni is bonded in a 12-coordinate geometry to three equivalent Hf, six Ni, and three equivalent Si atoms. There are three shorter (2.57 Å) and three longer (2.64 Å) Ni–Ni bond lengths. All Ni–Si bond lengths are 2.33 Å. In the second Ni site, Ni is bonded in a 4-coordinate geometry to three equivalent Hf, six Ni, and four Si atoms. All Ni–Ni bond lengths are 2.69 Å. There are one shorter (2.33 Å) and three longer (2.52 Å) Ni–Si bond lengths. There are two inequivalent Si sites. In the first Si site, Si is bonded to four equivalent Hf and eight Ni atoms to form a mixture of face and corner-sharing SiHf4Ni8 cuboctahedra. In the second Si site, Si is bonded in a body-centered cubic geometry to eight equivalent Ni atoms.

36 MATERIALS SCIENCE↗