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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 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Hg3(SeI)2 by Materials Project

Hg3Se2I2 crystallizes in the orthorhombic Imma space group. The structure is three-dimensional. there are three inequivalent Hg2+ sites. In the first Hg2+ site, Hg2+ is bonded in a 4-coordinate geometry to two equivalent Se2- and two equivalent I1- atoms. Both Hg–Se bond lengths are 2.60 Å. Both Hg–I bond lengths are 3.19 Å. In the second Hg2+ site, Hg2+ is bonded in a 6-coordinate geometry to two equivalent Se2- and four I1- atoms. Both Hg–Se bond lengths are 2.57 Å. There are a spread of Hg–I bond distances ranging from 3.19–3.83 Å. In the third Hg2+ site, Hg2+ is bonded in a 5-coordinate geometry to two equivalent Se2- and three I1- atoms. Both Hg–Se bond lengths are 2.59 Å. There are a spread of Hg–I bond distances ranging from 3.12–3.82 Å. Se2- is bonded in a 3-coordinate geometry to three Hg2+ atoms. There are three inequivalent I1- sites. In the first I1- site, I1- is bonded in a 3-coordinate geometry to four Hg2+ atoms. In the second I1- site, I1- is bonded in a distorted L-shaped geometry to four equivalent Hg2+ atoms. In the third I1- site, I1- is bonded in a 4-coordinate geometry to six Hg2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Hg3(SeI)2 by Materials Project

Hg3Se2I2 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are four inequivalent Hg2+ sites. In the first Hg2+ site, Hg2+ is bonded in a 4-coordinate geometry to two Se2- and four I1- atoms. There are one shorter (2.58 Å) and one longer (2.60 Å) Hg–Se bond lengths. There are a spread of Hg–I bond distances ranging from 3.17–3.93 Å. In the second Hg2+ site, Hg2+ is bonded in a 6-coordinate geometry to two equivalent Se2- and four I1- atoms. Both Hg–Se bond lengths are 2.57 Å. There are a spread of Hg–I bond distances ranging from 3.22–3.88 Å. In the third Hg2+ site, Hg2+ is bonded to two Se2- and four I1- atoms to form a mixture of distorted corner and edge-sharing HgSe2I4 octahedra. The corner-sharing octahedra tilt angles range from 0–4°. Both Hg–Se bond lengths are 2.57 Å. There are a spread of Hg–I bond distances ranging from 3.40–3.69 Å. In the fourth Hg2+ site, Hg2+ is bonded in a 4-coordinate geometry to two equivalent Se2- and two I1- atoms. Both Hg–Se bond lengths are 2.60 Å. There are one shorter (3.07 Å) and one longer (3.23 Å) Hg–I bond lengths. There are two inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 3-coordinate geometry to three Hg2+ atoms. In the second Se2- site, Se2- is bonded in a 3-coordinate geometry to three Hg2+ atoms. There are five inequivalent I1- sites. In the first I1- site, I1- is bonded in a 4-coordinate geometry to four Hg2+ atoms. In the second I1- site, I1- is bonded in a distorted trigonal non-coplanar geometry to three Hg2+ atoms. In the third I1- site, I1- is bonded in a 6-coordinate geometry to six Hg2+ atoms. In the fourth I1- site, I1- is bonded in a 8-coordinate geometry to eight Hg2+ atoms. In the fifth I1- site, I1- is bonded in a 4-coordinate geometry to ten Hg2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Selective NMR observation of the SEI–metal interface by dynamic nuclear polarisation from lithium metal

While lithium metal represents the ultimate high-energy-density battery anode material, its use is limited by dendrite formation and associated safety risks, motivating studies of the solid–electrolyte interphase layer that forms on the lithium, which is key in controlling lithium metal deposition. Dynamic nuclear polarisation enhanced NMR can provide important structural information; however, typical exogenous dynamic nuclear polarisation experiments, in which organic radicals are added to the sample, require cryogenic sample cooling and are not selective for the interface between the metal and the solid–electrolyte interphase. Here we instead exploit the conduction electrons of lithium metal to achieve an order of magnitude hyperpolarisation at room temperature. We enhance the 7 Li, 1 H and 19 F NMR spectra of solid–electrolyte interphase species selectively, revealing their chemical nature and spatial distribution. These experiments pave the way for more ambitious room temperature in situ dynamic nuclear polarisation studies of batteries and the selective enhancement of metal–solid interfaces in a wider range of systems.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1989

Application of reusable software components at the SEI

Robert Holibaugh of the Software Engineering Institute described a project which is studying the application of reusable software components. The primary goals are to gain practical experience with state-of-the-art reusable components, methods, and tools and to capture the lessons learned in the application of reuse technology. In addition the project will assess the impact of reuse on the software development process and products and will identify and validate the information that facilities software reuse during system development. The project includes two tasks - a reuse experiment and a redevelopment effort. The reuse experiment will define a life cycle and a methodology for reuse-based development, and define and implement a data collection mechanism for measuring the development. The redevelopment effort will construct a reuse test bed and will redevelop and realistically test subsystems from an embedded mission-critical real-time application. The reuse experiment will produce several products including a tested real-time application, reuse-based components and tools evaluation, a reuse-based development method, a framework for data collection, a framework for measuring productivity, and lessons learned data. Successful development with reusable components will require a rich set of components and an integrating methodology. The Tomahawk Land Attack Missile system is the application for the redevelopment effort.

Holibaugh, Robert↗
NASA NTRS1990

Software engineering activities at SEI (Software Engineering Institute)

Prototyping was shown to ease system specification and implementation, especially in the area of user interfaces. Other prototyping approaches do not allow for the evolution of the prototype into a production system or support maintenance after the system is fielded. A set of goals is presented for a modern user interface environment and Serpent, a prototype implementation that achieves these goals, is described.

Chittister, Clyde↗
NASA NTRS1991

SEI rover solar-electrochemical power system options

A trade study of power system technology for proposed lunar vehicles and servicers is presented. A variety of solar-based power systems were selected and analyzed for each. The analysis determined the power system mass, volume, and deployed area. A comparison was made between periodic refueling/recharging systems and onboard power systems to determine the most practical system. The trade study concluded that the power system significantly impacts the physical characteristics of the vehicle. The refueling/recharging systems were lighter and more compact, but dependent on availability of established lunar base infrastructure. Onboard power systems pay a mass penalty for being fully developed systems.

Withrow, Colleen A.↗
NASA NTRS1991

Laser photovoltaic power system synergy for SEI applications

Solar arrays can provide reliable space power, but do not operate when there is no solar energy. Photovoltaic arrays can also convert laser energy with high efficiency. One proposal to reduce the required mass of energy storage required is to illuminate the photovoltaic arrays by a ground laser system. It is proposed to locate large lasers on cloud-free sites at one or more ground locations, and use large lenses or mirrors with adaptive optical correction to reduce the beam spread due to diffraction or atmospheric turbulence. During the eclipse periods or lunar night, the lasers illuminate the solar arrays to a level sufficient to provide operating power.

Landis, Geoffrey A.↗
NASA NTRS1991

SEI needs for space nuclear power

The use of nuclear electric propulsion (NEP) and nuclear thermal propulsion (NTP) for transportation to the moon and Mars is examined, and the use on Mars and moon bases of thermal conversion subsystems based on either a Brayton or a Stirling cycle is examined. It is shown that both cycles are attractive alternatives for those applications where continuous field operation is desired. Nuclear power systems have a clear advantage with regard to the moon and a lesser one with regard to Mars.

Brandhorst, H. W.↗
NASA NTRS1991

SP-100 materials technology for SEI applications

General Electric and selected National laboratories are developing the SP-100 concept under the sponsorship of DOE,NASA and SDIO. Near term Space Exploration Initiative goals include the establishment of a lunar base, interplanetary manned missions, and the eventual establishment of a base on Mars. All of these projected missions have substantial power requirements. The SP-100 nuclear reactor has been identified as a promising power source to meet these requirements. This paper describes the material selections for SP-100, the factors driving the selection, and the progress to date in solving fabrication problems and producing the necessary properties data base.

Ring, P. J.↗