Tip vortex computer code SRATIP. User's guide

This User's Guide applies to the three dimensional viscous flow forward marching analysis, PEPSIG, as used for the calculation of the helicopter tip vortex flow field. The guide presents a discussion of the program flow and subroutines, as well as a list of sample input and output

A three-dimensional viscous flow analysis for the helicopter tip vortex generation problem

The tip vortex flow field occurring in the vicinity of the tip region of a a helicopter rotor blade is a very complicated three-dimensional, viscous flow phenomenon. The details of the flow in the tip region can have a major effect in determining the generated rotor noise and can significantly affect the performance and dynamic loading of the rotor blade. The three-dimensional viscous subsonic tip vortex generation processes is investigated by a numerical procedure which allows spatial forward-marching integration, utilizing flow approximations from the velocity-decomposition approach of Briley and McDonald. The approach has been applied to compute the laminar and turbulent tip vortex flows for a constant thickness slab airfoil with a square tip, a constant thickness slab airfoil with a half round tip and a NACA 0012 airfoil with a half round tip. The basic mechanism of the tip vortex generation process as well as the prediction of vortex appearance, strength and secondary flow shown by the calculations are in qualitative agreement with experimental results

Different steady states for spin currents in noncollinear multilayers

We find there are at least two different steady states for transport across noncollinear magnetic multilayers. In the conventional one there is a discontinuity in the spin current across the interfaces which has been identified as the source of current induced magnetic reversal; in the one advocated herein the spin torque arises from the spin accumulation transverse to the magnetization of a magnetic layer. These two states have quite different attributes which should be discerned by current experiments.Comment: 8 pages, no figure. Accepted for publication in Journal of Physics: Condensed Matte

Command system study for the operation and control of unmanned scientific satellites. task ii closed-loop /feedback/ verification techniques second quarterly progress report, 30 sep. - 31 dec. 1964

Closed loop, feedback verification techniques for command system of unmanned scientific satellit

QUASAT: An orbiting very long baseline interferometer program using large space antenna systems

QUASAT, which stands for QUASAR SATELLITE, is the name given to a new mission being studied by NASA. The QUASAT mission concept involves a free flying Earth orbiting large radio telescope, which will observe astronomical radio sources simultaneously with ground radio telescopes. The primary goal of QUASAT is to provide a system capable of collecting radio frequency data which will lead to a better understanding of extremely high energy events taking place in a variety of celestial objects including quasars, galactic nuclei, interstellar masers, radio stars and pulsars. QUASAT's unique scientific contribution will be the increased resolution in the emission brightness profile maps of the celestial objects

A study of solid-propellant vaporization and diffusion processes Final technical report

Vaporization rate and diffusion coefficient determined for organic additives to polyurethane solid propellants - dioctyl adipate and ferrocen

Consumer Research Needs from the Food and Drug Administration on Front-of-Package Nutritional Labeling

Americans have increasingly busy lifestyles and desire quick and nutritious food choices. To provide consumers with at-a-glance nutrition information, many food manufacturers have introduced front-of-package (FOP) nutritional labeling systems. The purpose of this review is to reach out to the marketing and public policy discipline by identifying research needs on FOP systems not only to aid decision making for federal agencies, but also to help advance research on this important topic. We describe the many FOP systems, the FDA\u27s regulatory background and approach to FOP systems, recent experimental research and gaps in knowledge, and research needs on FOP nutrition labeling

Subharmonic gap structure in short ballistic graphene junctions

We present a theoretical analysis of the current-voltage characteristics of a ballistic superconductor-normal-superconductor (SNS) junction, in which a strip of graphene is coupled to two superconducting electrodes. We focus in the short-junction regime, where the length of the strip is much smaller than superconducting coherence length. We show that the differential conductance exhibits a very rich subharmonic gap structure which can be modulated by means of a gate voltage. On approaching the Dirac point the conductance normalized by the normal-state conductance is identical to that of a short diffusive SNS junction.Comment: revtex4, 4 pages, 4 figure