Coupled rotor-body equations of motion hover flight

A set of linearized equations of motion to predict the linearized dynamic response of a single rotor helicopter in a hover trim condition to cyclic pitch control inputs is described. The equations of motion assume four fuselage degrees of freedom: lateral and longitudinal translation, roll angle, pitch angle: four rotor degrees of freedom: flapping (lateral and longitudinal tilt of the tip path plane), lagging (lateral and longitudinal displacement of the rotor plane center of mass); and dynamic inflow (harmonic components). These ten degrees of freedom correspond to a system with eighteen dynamic states. In addition to examination of the full system dynamics, the computer code supplied with this report permits the examination of various reduced order models. The code is presented in a specific form such that the dynamic response of a helicopter in flight can be investigated. With minor modifications to the code the dynamics of a rotor mounted on a flexible support can also be studied

Molecular collisions. 15 - Classical limit of the generalized phase shift treatment of rotational excitation - Atom-rigid rotor

Generalized phase shift approach to problem of rotationally inelastic molecular collision

Molecular collisions. 16: Comparison of GPS with classical trajectory calculations of rotational inelasticity for the Ar-N2 system

Comparison of generalized phase shift treatment with classical trajectory calculations of rotational inelasticity cross sections of Ar-N2 scatterin

Design and numerical evaluation of full-authority flight control systems for conventional and thruster-augmented helicopters employed in NOE operations

The development and methodology is presented for development of full-authority implicit model-following and explicit model-following optimal controllers for use on helicopters operating in the Nap-of-the Earth (NOE) environment. Pole placement, input-output frequency response, and step input response were used to evaluate handling qualities performance. The pilot was equipped with velocity-command inputs. A mathematical/computational trajectory optimization method was employed to evaluate the ability of each controller to fly NOE maneuvers. The method determines the optimal swashplate and thruster input histories from the helicopter's dynamics and the prescribed geometry and desired flying qualities of the maneuver. Three maneuvers were investigated for both the implicit and explicit controllers with and without auxiliary propulsion installed: pop-up/dash/descent, bob-up at 40 knots, and glideslope. The explicit controller proved to be superior to the implicit controller in performance and ease of design

Optical excitations in organic molecules, clusters and defects studied by first-principles Green's function methods

Spectroscopic and optical properties of nanosystems and point defects are discussed within the framework of Green's function methods. We use an approach based on evaluating the self-energy in the so-called GW approximation and solving the Bethe-Salpeter equation in the space of single-particle transitions. Plasmon-pole models or numerical energy integration, which have been used in most of the previous GW calculations, are not used. Fourier transforms of the dielectric function are also avoided. This approach is applied to benzene, naphthalene, passivated silicon clusters (containing more than one hundred atoms), and the F center in LiCl. In the latter, excitonic effects and the $1s \to 2p$ defect line are identified in the energy-resolved dielectric function. We also compare optical spectra obtained by solving the Bethe-Salpeter equation and by using time-dependent density functional theory in the local, adiabatic approximation. From this comparison, we conclude that both methods give similar predictions for optical excitations in benzene and naphthalene, but they differ in the spectra of small silicon clusters. As cluster size increases, both methods predict very low cross section for photoabsorption in the optical and near ultra-violet ranges. For the larger clusters, the computed cross section shows a slow increase as function of photon frequency. Ionization potentials and electron affinities of molecules and clusters are also calculated.Comment: 9 figures, 5 tables, to appear in Phys. Rev. B, 200

Molecular collisions. 14 - First-order approximation of the generalized phase shift treatment of rotational excitation - Atom-rigid rotor

Applying generalized phase shift approach to rotational excitation problem to atom-rigid rotor case in first order approximatio

Book Reviews

BOOK REVIEWS The Swiss Way of Welfare: Lessons for the Western World. Ralph Segalman. New York: Praeger, 1986, 205 pp., $39.95. - Reviewed by Isidor Walliman Vieillesses: Situations, Itineraires et Modes de Vie des Personnes Agees Aujourd\u27Hui. Christian Lalive d\u27Epiany (Ed.). Saint Saphorin, Switzerland: Edition Georgi, 1983. - Reviewed by Elizabeth D. Huttman with the assistance of Anna Marie Rampmaier and W and N. Weber. Wohlfahrtsstaat Schweiz (The Swiss Welfare State). Antonin Wagner. Bern: Paul Haupt, 1985, 248 pp., S.E 32. - Reviewed by Shimon S. Gottschalk The Mean Season: The Attack on the Welfare State. Fred Block, Richard A. Cloward, Barbara Ehrenreich, Frances Fox Piven. New York: Pantheon Books, 1987, 205 pp.,$8.95. - Reviewed by Robert Sheak Shared Responsibility: Families and Social Policy. Robert M. Moroney. Hawthorne, N.Y.: Aldine Publishing Co., 1986, $31.95 cloth,$14.94 paper. - Reviewed by Christina R. Curtiss