Search NASA⌕ Search

SEARCH · Search NASA

Results for “matrix”

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 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
NASA NTRS1984

The mineral chemistry and origin of inclusion matrix and meteorite matrix in the Allende CV3 chondrite

The mineralogy and mineral chemistry of the inclusion and meteorite matrices in the Allende CV3 chondrite are described, and the physical and chemical parameters of the conventional equilibrium condensation model of the origin of chondrite meteorites are evaluated. An alternative model of the origin of the mafic constituent of Allende inclusions is presented, on the basis of a new model of chondrule petrogenesis and the physical evolution of the primitive solar nebula. The model shows that the mineral chemistry of the olivine matrix in Allende CV3 seems to preserve a good record of nebular and planetary processes, including: (1) vapor-to-solid condensation under relatively oxidizing nonequilibrium conditions; (2) Fe/Mg equilibration in the meteorite parent body; and (3) recrystallization and incipient melting in the solar nebula.

Kornacki, A. S.↗
NASA NTRS1991

Effect of fiber-matrix debonding on notched strength of titanium metal matrix composites

Two specimen configuration of a (0/90)2s SCS-6/Ti-15-3 laminate were tested and analyzed: a center hole (CH) specimen and a double edge notch (DEN) specimen. The two specimen configurations failed at similar stress levels. Two analytical techniques, a 3-D finite-element analysis and a macro-micromechanical analysis were used to predict the overall stress-deformation behavior and the notch-tip fiber-matrix interface stresses in both configurations.

Bigelow, C. A.↗
NASA NTRS1991

The role of matrix material and CCl4 (electron acceptor) on the ionization mechanisms of matrix-isolated naphthalene

The formation mechanisms and optical properties of polycyclic aromatic hydrocarbons (PAH) isolated in argon and neon matrices were studied in a systematic manner in an attempt to provide spectroscopic data on PAH ions under conditions relevant to astrophysical applications. The results obtained indicate the strong influence of the matrix material on the competing radiative (fluorescence and phosphorescence) and nonradiative (internal conversion and intersystem crossing) relaxation processes of the trapped molecule.

Salama, F.↗
DOE OSTI2014

Space-time S-matrix and flux tube S-matrix II. Extracting and matching data

We elaborate on a non-perturbative formulation of scattering amplitudes/null polygonal Wilson loops in planar N=4 Super-Yang-Mills theory. The construction is based on a decomposition of the Wilson loop into elementary building blocks named pentagon transitions. Our discussion expands on a previous letter of the authors where these transitions were introduced and analyzed for the so-called gluonic excitations. In this paper we revisit these transitions and extend the analysis to the sector of scalar excitations. We restrict ourselves to the single particle transitions and bootstrap their finite coupling expressions using a set of axioms. Besides these considerations, the main focus of the paper is on the extraction of perturbative data from scattering amplitudes at weak coupling and its comparison against the proposed pentagon transitions. We present several tests for both the hexagon and heptagon (MHV and NMHV) amplitudes up to two- and three-loop orders. In attached notebooks we provide explicit higher-loop predictions obtained from our method.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2014

Space-time S-matrix and flux-tube S-matrix III. The two-particle contributions

We consider light-like Wilson loops with hexagonal geometry in the planar limit of N=4 Super-Yang-Mills theory. Within the Operator-Product-Expansion framework these loops receive contributions from all states that can propagate on top of the colour flux tube sourced by any two opposite edges of the loops. Of particular interest are the two-particle contributions. They comprise virtual effects like the propagation of a pair of scalars, fermions, and gluons, on top of the flux tube. Each one of them is thoroughly discussed in this paper. Our main result is the prediction of all the twist-2 corrections to the expansion of the dual 6-gluons MHV amplitude in the near-collinear limit at finite coupling. At weak coupling, our result was recently used by Dixon, Drummond, Duhr and Pennington to predict the full amplitude at four loops. At strong coupling, it allows us to make contact with the classical string description and to recover the (previously elusive) AdS 3 mode from the continuum of two-fermion states. More generally, the two-particle contributions serve as an exemplar for all the multi-particle corrections.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2014

Space-time S-matrix and flux-tube S-matrix IV. Gluons and fusion

We analyze the pentagon transitions involving arbitrarily many flux-tube gluonic excitations and bound states thereof in planar N=4 Super-Yang-Mills theory. We derive all-loop expressions for all these transitions by factorization and fusion of the elementary transitions for the lightest gluonic excitations conjectured in a previous paper. We apply the proposals so obtained to the computation of MHV and NMHV scattering amplitudes at any loop order and find perfect agreement with available perturbative data up to four loops.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗