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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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Atomic collision theory, discussing cross section calculations by Gryzinski classical method, variational methods and Fadeev equations for three particles
Atom-atom collisional excitation cross sections obtained from ionization cross sections, noting Thomson classical theory
Classical Cepheid variables and their spectra, infrared astronomy, and interstellar matter
Vibrational effects in ion-dipole collisions with classical tunneling
Energy accommodation coefficients for He3-W and He4-W, comparing results with classical gas-solid interaction theory
Closed universe classical and quantum dynamics by ADM Hamiltonian treatment of Einstein equations for homogeneous cosmological models
Two point hydrodynamic equation for molecular fluctuations divergent growth in classical shear flow via B-B-G-K-Y procedure and double series moment expansion
Classical relaxation of Br2 molecules in argon heat bath
Procedure to replace electron correlation effects with Debye shielded interaction including classical path broadening functions for Stark effects
Classical trajectory study of rotationally inelastic scattering of hydrogen molecules by collisions with lithium ions
Comparison of generalized phase shift treatment with classical trajectory calculations of rotational inelasticity cross sections of Ar-N2 scattering
Classic fourth and lower order Runge-Kutta formulas with stepsize control, applying to heat transfer problems
Classical Poincare-von Zeipel canonical perturbation theory extension to adiabatically perturbed systems with slow dependence on time or dynamic variables
A classical model for laser action is discussed, in which an active medium consisting of anharmonic oscillators interacts with an electromagnetic field in a resonant cavity. Comparison with the case of a medium consisting of harmonic oscillators shows the significance of nonlinearities for producing self-sustained oscillations in the radiation field. A theoretical model is presented for the pressure dependence of the intensity of a gas laser, in which only velocity-changing collisions with foreign gas atoms are included. A collision model for hard sphere, repulsive interactions was derived. Collision theory was applied to a third-order expansion of the polarization in powers of the cavity electric field (weak signal theory).
Derivation of a unified classical path theory of pressure broadening, using only elementary concepts. It is shown that the theory of Smith, Cooper and Vidal (1969) is only correct at all frequencies to first order in the number density of perturbers.
It is shown that in Dirac's version of the quantum theory of gravitation, the Hamiltonian constraints are greatly redundant. If the Hamiltonian constraint condition is satisfied at one point on the underlying, closed three-dimensional manifold, then it is automatically satisfied at every point, provided only that the momentum constraints are everywhere satisfied. This permits one to replace the usual infinity of Hamiltonian constraints by a single condition which may be taken in the form of an integral over the manifold. Analogous theorems are given for the classical Einstein Hamilton-Jacobi equations.
Many properties of gaseous systems such as electromagnetic absorption and emission, sound dispersion and absorption, may be elucidated if the nature of collisions between the particles in the system is understood. A procedure for the calculation of the classical trajectories of two interacting diatomic molecules is described. The dynamics of the collision will be assumed to be that of two rigid rotors moving in a specified potential. The actual outcome of a representative sample of many trajectories at 298K was computed, and the use of these values at any temperature for calculations of various molecular properties will be described. Calculations performed for the O2 microwave spectrum are given to demonstrate the use of the procedure described.
An alternative method for deriving the generalized inverse of an arbitrary rectangular matrix with real or complex coefficients is described. The method applies a classical minimization procedure without iteration processes and is readily applicable in digital computer programming.