17,783 research outputs found
On optical imaging through aircraft turbulent boundary layers
Optical resolution quality as affected by aircraft turbulent boundary layers is analyzed. Wind-tunnel data was analyzed to obtained the variation of boundary layer turbulence scale length and mass density rms fluctuations with Mach number. The data gave good agreement with a mass density fluctuation turbulence spectrum that is either isotropic of orthogonally anisotropic. The data did not match an isotropic turbulence velocity spectrum which causes an anisotropic non-orthogonal mass density fluctuation spectrum. The results indicate that the average mass density rms fluctuation is about 10% of the maximum mass density across the boundary layer and that the transverse turbulence scale size is about 10% of the boundary layer thickness. The results indicate that the effect of the turbulent boundary layer is large angle scattering which decreases contrast but not resolution. Using extinction as a criteria the range of acceptable aircraft operating conditions are given
THE CHANGING POLITICAL ENVIRONMENT FOR TOBACCO -- IMPLICATIONS FOR SOUTHERN TOBACCO FARMERS, RURAL ECONOMIES, TAXPAYERS, AND CONSUMERS: DISCUSSION
This paper is a discussion of the Brown, Snell, and Tiller article. The economic accuracy, conciseness, and organization is noteworthy with the major strength being the analysis of the tobacco system with the absence of a Federal program. The base paper discusses economic consequences of the U.S. tobacco program, within-industry structural differences, and recent/potential future changes such as the buy-out, industry uncertainty, and the possibility of program elimination.price-support program, tobacco industry, tobacco program, Agricultural and Food Policy,
General Tobacco Policy Survey Questions from the Tobacco Baling Survey
Crop Production/Industries,
Experimental L-band SST satellite communications/surveillance terminal study. Volume 1 - Study summary
Study of design for experimental L band supersonic transport communications/surveillance termina
A Photoelastic Study of Strain Waves Caused by Cavitation
Ultra-high-speed photoelastic techniques have been applied to a study of the transient stresses and strains in a photoelastic plastic when subject to cavitation. A photocell, used to detect the transient strains, indicated that the time duration of the strains was about 2
microseconds. Using an ultra-high-speed motion picture camera, ultrasonic cavitation bubbles have been photographed collapsing on the surface of a photoelastic specimen, and the resulting strain wave in
the solid has been photographed.
The dynamic properties of a photoelastic material have been
obtained in order to permit quantitative interpretation of the transients. This has indicated that the stresses due to cavitation may be as high as 2.8 x 10^5 psi.
The photoelastic plastic, CR-39, was found to exhibit strain
birefringence, and its strain-optic constant was found to be independent of the rate of loading
An Intermediate Theory of Longitudinal Stress Waves in Bars
The expressions for kinetic and strain energy for longitudinal stress waves in a bar are considered, first in a one-dimensional model in which cross sections are assumed to remain plane, and stresses in the radial and
circumferential direction are assumed to be zero. From this, an equation of motion is derived which is used to determine the speed of longitudinal sinusoidal stress waves as a function of wave length. Secondly, a simplified
three-dimensional model is considered where the axial motion is a parabolic function of the radius, from which the speed of sinusoidal stress waves is derived. The derived expressions are compared with previously
published solutions
- …