Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “FeIr”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

7 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1986

Experimental study of the influence of wind on Benjamin-Feir sideband instability

A laboratory investigation of the influence of wind on the evolution of mechanically generated regular (m.g.r.) waves is reported. Surface elevation measurements were made at four fetches for steep (0.1 less than ak(bar) less than 0.2, 2 Hz) m.g.r. waves, moderate (15 less than u(asterisk) less than 25 cm/s, 3-6 Hz) wind waves, and combinations of the m.g.r. and wind waves. The m.g.r. wave spectra exhibit Benjamin-Feir sidebands that grow exponentially with fetch and whose growth rate increases as the initial wave steepness increases. As fetch increases for the wind cases, total energy increases and the frequency of the spectral maximum downshifts, but no spectral lines representing Benjamin-Feir sidebands were detected even though the wave steepness and fetch were similar to the m.g.r. waves whose spectra displayed sidebands. As wind speed increased over the m.g.r. waves, sideband magnitude, sideband growth rate, and low-frequency perturbation components associated with the instability mechanism were reduced.

Bliven, L. F.↗
DOE OSTI2020

Materials Data on FeIr by Materials Project

FeIr crystallizes in the trigonal R-3m space group. The structure is three-dimensional. there are three inequivalent Fe sites. In the first Fe site, Fe is bonded to six equivalent Fe and six equivalent Ir atoms to form distorted FeFe6Ir6 cuboctahedra that share corners with twelve FeFe6Ir6 cuboctahedra, edges with twelve FeFe6Ir6 cuboctahedra, edges with twelve equivalent IrFe6Ir6 cuboctahedra, faces with six equivalent FeFe6Ir6 cuboctahedra, and faces with twelve equivalent IrFe6Ir6 cuboctahedra. All Fe–Fe bond lengths are 2.64 Å. All Fe–Ir bond lengths are 2.59 Å. In the second Fe site, Fe is bonded to six equivalent Fe and six Ir atoms to form distorted FeFe6Ir6 cuboctahedra that share corners with five equivalent IrFe6Ir10 cuboctahedra, corners with twelve FeFe6Ir6 cuboctahedra, edges with ten IrFe6Ir6 cuboctahedra, edges with twelve FeFe6Ir6 cuboctahedra, faces with six equivalent FeFe6Ir6 cuboctahedra, and faces with fifteen IrFe6Ir6 cuboctahedra. All Fe–Fe bond lengths are 2.64 Å. All Fe–Ir bond lengths are 2.59 Å. In the third Fe site, Fe is bonded to six equivalent Fe and six Ir atoms to form distorted FeFe6Ir6 cuboctahedra that share corners with five equivalent IrFe6Ir10 cuboctahedra, corners with twelve FeFe6Ir6 cuboctahedra, edges with ten IrFe6Ir6 cuboctahedra, edges with twelve FeFe6Ir6 cuboctahedra, faces with six equivalent FeFe6Ir6 cuboctahedra, and faces with fifteen IrFe6Ir6 cuboctahedra. All Fe–Fe bond lengths are 2.64 Å. All Fe–Ir bond lengths are 2.59 Å. There are two inequivalent Ir sites. In the first Ir site, Ir is bonded to six Fe and six equivalent Ir atoms to form distorted IrFe6Ir6 cuboctahedra that share corners with twelve IrFe6Ir6 cuboctahedra, edges with twelve FeFe6Ir6 cuboctahedra, edges with twelve IrFe6Ir6 cuboctahedra, faces with six equivalent IrFe6Ir6 cuboctahedra, and faces with twelve FeFe6Ir6 cuboctahedra. All Ir–Ir bond lengths are 2.64 Å. In the second Ir site, Ir is bonded to six Fe and ten equivalent Ir atoms to form distorted IrFe6Ir10 cuboctahedra that share corners with ten FeFe6Ir6 cuboctahedra, corners with twelve IrFe6Ir6 cuboctahedra, edges with eight FeFe6Ir6 cuboctahedra, edges with sixteen IrFe6Ir6 cuboctahedra, faces with sixteen equivalent IrFe6Ir10 cuboctahedra, and faces with eighteen FeFe6Ir6 cuboctahedra. There are a spread of Ir–Ir bond distances ranging from 2.64–5.28 Å.

36 MATERIALS SCIENCE↗
NASA NTRS1991

The Eckhaus and the Benjamin-Feir instability near a weakly inverted bifurcation

We investigate how the criteria for two prototype instabilities in one dimensional pattern forming systems, namely for the Eckhaus instability and for the Benjamin-Feir instability, change as one goes from a continuous bifurcation, to a spatially periodic or spatially and/or time periodic state, to the corresponding weakly inverted, i.e., hysteretic, cases. We also give the generalization to two dimensional patterns in systems with anisotropy as they arise from hydrodynamic instabilities in nematic liquid crystals.

Brand, Helmut R.↗
NASA NTRS1974

Evaluation of routing and scheduling considerations for possible future commercial hypersonic transport aircraft

Travel markets which would be served by high speed commercial transport aircraft and the ability of the airlines to schedule and route the aircraft in a way that would achieve good daily utilization and productivity are examined. The following areas are considered: (1) identification of the major long-haul city pairs that would most likely demand nonstop service; (2) selection of flight tracks observing alternative sonic boom restrictions; (3) estimation of flight times for all city pairs for the various sonic boom constraints; (4) impact of airport curfews on possible departure and arrival schedules; (5) projection of passenger traffic volumes on the selected city pairs; and (6) potential daily utilization and aircraft productivity.

Feir, J. B.↗
DOE OSTI2024

Gas permeable fluoropolymers and ionomers

Novel copolymers that are fluoropolymers including a first repeat unit that is fluorinated and cyclic and a second repeat unit from a trifluorovinyl methylene ether monomer having sulfur or sulfone functionality in the pendant group are disclosed. The copolymers have relatively high gas permeability as a result of a cyclic repeat unit in the copolymer backbone and ionomers from oxidation of the sulfur containing functionality are particularity useful in the cathode structure of a proton exchange membrane fuel cell.

Lousenberg, Robert Daniel↗