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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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Igneous and metamorphic rocks as simulated lunar rocks, determining elastic and attenuation symmetry by quasi-longitudinal pulse velocity and amplitude measurements on spherical specimens
Basis functions for arbitrary time variable network symmetries for large scale integration, using group theory
A correlation method is presented for approximating the temperature distribution in the plane of symmetry downstream of a jet injected normal to a uniform crossflow. Correlations are developed for the scaling parameters required to define the temperature profile at any desired location from the dimensionless universal form which has been experimentally observed. Profiles calculated using the correlation methods are compared with experimental profiles for several momentum and density ratios at various downstream distances.
The dependence of residual phase shifts upon the angle of inclination of the orbit for a model Martian atmosphere is examined. It is found that departures from spherical symmetry in the electron number density profiles result in changes of as much as an order of magnitude in the phase shifts of radio waves passing through the atmosphere and ionosphere of the model. These results confirm the earlier findings of Pirraglia and Gross (1970).
A theoretical study was made to delineate the effects of thermochemical nonequilibrium in the inviscid flow field of a representative space shuttle orbiter configuration. The study was based on experimental pressure data which was used as an input to a stream tube computer program. The pressure data from two configurations are tabulated. Calculations were restricted to the windward plane of symmetry and the calculations covered an altitude range from 200,000 to 250,000 feet at velocities of 16,000 to 24,000 feet per second respectively. Angles of attack of 20 and 40 degrees were included. The calculations show that the nonequilibrium effects are confined largely to the entropy layer expect at the highest altitude, where significant nonequilibrium effects are observed in the entire inviscid flow field.
Previous accurate dipole moment calculation techniques are modified to be applicable to higher excited states of symmetry. The self-consistent fields and configuration interactions are calculated for the X(2)Sigma(+) and B(2)Sigma(+) states of CN. Spin hyperfine constants and spin density at the nucleus are considered in the context of one-electron operator properties. The values of the self-consistent field and configuration interaction for the spin density are compared with experimental values for several diatomic molecules.
It is shown that the first order orbitals for X-alpha or Hartree-Fock atoms perturbed by multipole electric fields have the expected symmetry properties.
Predictions are presented for hypersonic, nonequilibrium viscous flows over nonanalytic blunt bodies at reentry conditions. Emphasis is placed on predictions of the viscous flowfield for the windward plane of symmetry of the space shuttle and other axisymmetric bodies which approximate the space shuttle geometry. The equations which govern the viscous shock-layer flow are presented, and the method by which the equations are solved is discussed. The predictions of the present finite-difference method are compared with predictions of other numerical methods as well as with experimental data.
Most fuselage geometries cover a portion of the wing leading edge near the plane of symmetry, and it seems reasonable to expect that a large fraction of the leading edge suction which would be developed by the covered wing at high angles of attack is not developed on the fuselage. This is one of the reasons that the Oswald span efficiency factor for the wing body combination fails to approach the value predicted by lifting line theory for the isolated wing. Some traditional and recent literature on wing-body interference is discussed and high Reynolds number data on wing-body-nacelle drag are reviewed. An exposed central leading edge geometry has been developed for a sailplane configuration. Low Reynolds number tests have not validated the design concept.
The general orbit-coverage problem in a simplified physical model is investigated by application of numerical approaches derived from basic number theory. A system of basic and general properties is defined by which idealized periodic coverage patterns may be characterized, classified, and delineated. The principal common features of these coverage patterns are their longitudinal quantization, determined by the revolution number R, and their overall symmetry.
The flowfield in the plane of symmetry of a thin lifting delta wing with supersonic leading edges is examined for wings with apex angles that are comparable to the Mach angle, as well as for the limiting case of a straight leading edge. For these two cases, a simplified treatment of the interaction between the plane expansion wave emanating from the trailing edge and the three-dimensional bow shock is presented. In the region unaffected by the wing tips, the shock decays inversely with distance from the wing.
The stress and displacement distribution in a layered medium is found by means of transfer matrices. The surface loading exhibits axial symmetry, and each layer is of infinite extent in the horizontal direction, of constant depth, and is considered to be linearly elastic, homogeneous, and isotropic. The method developed has the built-in advantage of enforcing interface continuity conditions automatically. Its application to layered composites shows the flexibility with which it predicts the local as well as the global response of the medium.
Selection rules for nonlinear three-wave interactions are derived on the basis of the symmetry of the background medium and the waves themselves. The process described bypasses the formal derivation of the coupling coefficient itself. The primary concern is with the effect of the polarization of the waves on the selection rules. Although consideration is limited to three-wave interactions, the method is easily generalized to more waves. Results are derived for these examples: three waves with parallel propagation vectors in an unmagnetized medium, and three waves propagating parallel, and then perpendicular, to a static magnetic field.
The observable phase factor is taken as a basic concept for the description of electromagnetism. Generalization of this concept to SU(2) and SU(2) x U(1) groups is carried out in such a way that the monopoles with quantized charges appear naturally and that the symmetry between the electric and magnetic phenomena is preserved. Some physical implications are discussed.
General covariance and maximum four-dimensional Yang-Mills gauge symmetry lead to these results: (1) gravity is characterized by a dimensionless constant F of the order of 10 to the -19th; (2) the Newtonian force is always attractive; (3) space-time has a torsion; and (4) gravitational spin-force between two protons is about 10 to the 19th times stronger than the corresponding Newtonian force. A possible experimental test is discussed.
Based on the exact crystal structure of decahedral and icosahedral particles, high energy electron diffraction patterns and image profiles have been derived for various high symmetry orientations of the particles with respect to the incident beam. These results form a basis for the identification of small metal particle structures with advanced methods of transmission electron microscopy.
An improved procedure for the three dimensional finite element analysis of an angle ply laminate with a circular hole is discussed. The procecure exploits polar symmetry and is the basis for a new finite element computer code. For the broad class of laminates that contain angle plies, this code requires only one half as much computing capacity as conventional codes.
It is shown that the presence of a phase transition early in the history of the universe, associated with spontaneous symmetry breaking (believed to take place at very high temperatures at which the various fundamental interactions unify), significantly modifies its dynamics and evolution. This is due to the energy 'pumping' during the phase transition from the vacuum to the substance, rather than the gravitating effects of the vacuum. The expansion law of the universe then differs substantially from the relation considered so far for the very early time expansion. In particular it is shown that under certain conditions this expansion law is exponential. It is further argued that under reasonable assumptions for the mass of the associated Higgs boson this expansion stage could last long enough to potentially account for the observed isotropy of the universe.