Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “U(OF)2”

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.

At least 181 records · Page 10
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on U(CuP)2 by Materials Project

UCu2P2 crystallizes in the trigonal P-3m1 space group. The structure is three-dimensional. U4+ is bonded to six equivalent P3- atoms to form UP6 octahedra that share corners with twelve equivalent CuP4 tetrahedra, edges with six equivalent UP6 octahedra, and edges with six equivalent CuP4 tetrahedra. All U–P bond lengths are 2.77 Å. Cu1+ is bonded to four equivalent P3- atoms to form CuP4 tetrahedra that share corners with six equivalent UP6 octahedra, corners with six equivalent CuP4 tetrahedra, edges with three equivalent UP6 octahedra, and edges with three equivalent CuP4 tetrahedra. The corner-sharing octahedra tilt angles range from 19–54°. There are three shorter (2.35 Å) and one longer (2.40 Å) Cu–P bond lengths. P3- is bonded to three equivalent U4+ and four equivalent Cu1+ atoms to form a mixture of distorted edge and corner-sharing PU3Cu4 pentagonal bipyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on U(OF)2 by Materials Project

UO2F2 crystallizes in the trigonal R-3m space group. The structure is two-dimensional and consists of three UO2F2 sheets oriented in the (0, 0, 1) direction. U6+ is bonded to two equivalent O2- and six equivalent F1- atoms to form distorted edge-sharing UO2F6 hexagonal bipyramids. Both U–O bond lengths are 1.78 Å. All U–F bond lengths are 2.45 Å. O2- is bonded in a single-bond geometry to one U6+ atom. F1- is bonded in a trigonal planar geometry to three equivalent U6+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on U(SiRu)2 by Materials Project

URu2Si2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. U4+ is bonded to eight equivalent Si4- atoms to form USi8 hexagonal bipyramids that share corners with sixteen equivalent RuSi4 tetrahedra, edges with four equivalent USi8 hexagonal bipyramids, edges with eight equivalent RuSi4 tetrahedra, and faces with four equivalent USi8 hexagonal bipyramids. All U–Si bond lengths are 3.16 Å. Ru2+ is bonded to four equivalent Si4- atoms to form RuSi4 tetrahedra that share corners with eight equivalent USi8 hexagonal bipyramids, corners with four equivalent RuSi4 tetrahedra, edges with four equivalent USi8 hexagonal bipyramids, and edges with four equivalent RuSi4 tetrahedra. All Ru–Si bond lengths are 2.39 Å. Si4- is bonded in a 9-coordinate geometry to four equivalent U4+, four equivalent Ru2+, and one Si4- atom. The Si–Si bond length is 2.39 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on U(SiPd)2 by Materials Project

UPd2Si2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. U4+ is bonded to eight equivalent Si4- atoms to form USi8 hexagonal bipyramids that share corners with sixteen equivalent PdSi4 tetrahedra, edges with four equivalent USi8 hexagonal bipyramids, edges with eight equivalent PdSi4 tetrahedra, and faces with four equivalent USi8 hexagonal bipyramids. All U–Si bond lengths are 3.09 Å. Pd2+ is bonded to four equivalent Si4- atoms to form PdSi4 tetrahedra that share corners with eight equivalent USi8 hexagonal bipyramids, corners with four equivalent PdSi4 tetrahedra, edges with four equivalent USi8 hexagonal bipyramids, and edges with four equivalent PdSi4 tetrahedra. All Pd–Si bond lengths are 2.49 Å. Si4- is bonded in a 9-coordinate geometry to four equivalent U4+, four equivalent Pd2+, and one Si4- atom. The Si–Si bond length is 2.30 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on U(SiAu)2 by Materials Project

UAu2Si2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. U6+ is bonded to eight equivalent Si4- atoms to form USi8 hexagonal bipyramids that share corners with sixteen equivalent AuSi4 tetrahedra, edges with four equivalent USi8 hexagonal bipyramids, edges with eight equivalent AuSi4 tetrahedra, and faces with four equivalent USi8 hexagonal bipyramids. All U–Si bond lengths are 3.18 Å. Au1+ is bonded to four equivalent Si4- atoms to form AuSi4 tetrahedra that share corners with eight equivalent USi8 hexagonal bipyramids, corners with four equivalent AuSi4 tetrahedra, edges with four equivalent USi8 hexagonal bipyramids, and edges with four equivalent AuSi4 tetrahedra. All Au–Si bond lengths are 2.58 Å. Si4- is bonded in a 9-coordinate geometry to four equivalent U6+, four equivalent Au1+, and one Si4- atom. The Si–Si bond length is 2.30 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on U(HO2)2 by Materials Project

UO2(OH)2 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. U6+ is bonded to six O2- atoms to form corner-sharing UO6 octahedra. The corner-sharing octahedral tilt angles are 41°. There are a spread of U–O bond distances ranging from 2.00–2.32 Å. H1+ is bonded in a single-bond geometry to two O2- atoms. There is one shorter (1.00 Å) and one longer (1.72 Å) H–O bond length. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to two equivalent U6+ and one H1+ atom. In the second O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one U6+ and one H1+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Lattice $ \mathcal{N} $ = 4 super Yang-Mills at strong coupling

In this paper we present results from numerical simulations of N = 4 super Yang-Mills for two color gauge theory over a wide range of ’t Hooft coupling 0 < λ ≤ 30 using a supersymmetric lattice action. Numerical study of this lattice theory has been stymied until recently by both sign problems and the occurrence of lattice artifact phases at strong coupling. We have recently developed a new action that appears capable of solving both problems. The resulting action possesses just SU(2) rather than U(2) gauge symmetry. By explicit computations of the fermion Pfaffian we present evidence that the theory possesses no sign problem and exists in a single phase out to arbitrarily strong coupling. Furthermore, preliminary work shows that the logarithm of the supersymmetric Wilson loop varies as the square root of the ’t Hooft coupling λ for large λ in agreement with holographic predictions.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2021

Mechanistic verification of empirical UO 2 fuel fracture models

Standard UO 2 fuel pellets used in light-water reactors fracture during irradiation due to the large thermal gradient in the radial direction. Over the decades, numerous researchers have explored fuel cracking from experimental and modeling points of view. To date, there have been both empirical and mechanistic approaches to predict the number of fragments that form in UO 2 . The empirical models only consider maximum power and burnup as inputs. Existing mechanistic approaches for normal operation have not accounted for irradiation effects. Here, this work employs a mechanistic fuel cracking model using the extended finite element method to explore radial crack formation while including a sensitivity analysis that accounts for the randomization of tensile strength within the fuel, the strength randomization criteria (uniform or volume-weighted Weibull), power ramping rates, computational mesh density, maximum power level, and irradiation (burnup) effects. The results indicate that the uncertainty in this mechanistic modeling approach envelopes the predicted values from three different empirical correlations in almost all cases. This means that, for computationally intensive analyses involving UO 2 fragmentation, the empirical correlations can be used. However, since the mechanistic calculations bound those of the empirical correlations, there is confidence in the applicability of the mechanistic approach developed in this work to generate a correlation for fuel types where limited data exists (e.g., doped-UO 2 , U 3 Si 2 ).

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2024

Digitization and subduction of S U ( N ) gauge theories

The simulation of lattice gauge theories on quantum computers necessitates digitizing gauge fields. One approach involves substituting the continuous gauge group with a discrete subgroup, but the implications of this approximation still need to be clarified. To gain insights, we investigate the subduction of S U ( 2 ) and S U ( 3 ) to discrete crystal-like subgroups. Using classical lattice calculations, we show that subduction offers valuable information based on subduced direct sums, helping us identify additional terms to incorporate into the lattice action that can mitigate the effects of digitization. Furthermore, we compute the static potentials of all irreducible representations of Σ ( 360 × 3 ) at a fixed lattice spacing. Our results reveal a percent-level agreement with the Casimir scaling of S U ( 3 ) for irreducible representations that subduce to a single Σ ( 360 × 3 ) irreducible representation. This provides a diagnostic measure of approximation quality, as some irreducible representations closely match the expected results while others exhibit significant deviations. Published by the American Physical Society 2024

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
NASA NTRS1978

The importance of quadrupole sources in prediction of transonic tip speed propeller noise

A theoretical analysis is presented for the harmonic noise of high speed, open rotors. Far field acoustic radiation equations based on the Ffowcs-Williams/Hawkings theory are derived for a static rotor with thin blades and zero lift. Near the plane of rotation, the dominant sources are the volume displacement and the rho U(2) quadrupole, where u is the disturbance velocity component in the direction blade motion. These sources are compared in both the time domain and the frequency domain using two dimensional airfoil theories valid in the subsonic, transonic, and supersonic speed ranges. For nonlifting parabolic arc blades, the two sources are equally important at speeds between the section critical Mach number and a Mach number of one. However, for moderately subsonic or fully supersonic flow over thin blade sections, the quadrupole term is negligible. It is concluded for thin blades that significant quadrupole noise radiation is strictly a transonic phenomenon and that it can be suppressed with blade sweep. Noise calculations are presented for two rotors, one simulating a helicopter main rotor and the other a model propeller. For the latter, agreement with test data was substantially improved by including the quadrupole source term.

Hanson, D. B.↗
DOE OSTI2020

Materials Data on U(GeRh)2 by Materials Project

Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on U(MoO4)2 by Materials Project

Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on U(MoO4)2 by Materials Project

Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on U(C2O5)2 by Materials Project

UO2(CO2)4 crystallizes in the orthorhombic Ccce space group. The structure is zero-dimensional and consists of sixteen formic acid molecules and four pitchblend, uranium(iv) oxide, uranium(iv) dioxide, uranium dioxide molecules.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on U(HO2)2 by Materials Project

UO2(OH)2 crystallizes in the triclinic P1 space group. The structure is two-dimensional and consists of one molecular hydrogen;dihydrate molecule and one UO2 sheet oriented in the (0, 0, 1) direction. In the UO2 sheet, U6+ is bonded in a square co-planar geometry to four O2- atoms. There are a spread of U–O bond distances ranging from 2.05–2.11 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a linear geometry to two equivalent U6+ atoms. In the second O2- site, O2- is bonded in a linear geometry to two equivalent U6+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on U(HO2)2 by Materials Project

UO2(OH)2 crystallizes in the orthorhombic Cmce space group. The structure is zero-dimensional and consists of four pitchblend, uranium(iv) oxide, uranium(iv) dioxide, uranium dioxide molecules and eight water molecules.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on U(HO2)2 by Materials Project

UO2(OH)2 crystallizes in the orthorhombic Cmc2_1 space group. The structure is zero-dimensional and consists of four pitchblend, uranium(iv) oxide, uranium(iv) dioxide, uranium dioxide molecules and eight water molecules.

36 MATERIALS SCIENCE↗