A look at the commonly used LANDSAT vegetation indices

The origins, development, and logic of the indices are discussed. The relationships of the indices to ground-based measurements of vegetation are highlighted. An effort was made to preserve the order in which the various indices appeared in the literature in order to historically trace their underlying concepts

Area estimation of environmental phenomena from NOAA-n satellite data

A technique for documenting changes in size of NOAA-n pixels in order to calibrate the data for use in performing area calculations is described. Based on Earth-satellite geometry, a function for calculating the effective pixel size, measured in terms of ground area, on any given pixel was derived. The equation is an application of the law of sines plus an arclength formula. Effective pixel dimensions for NOAA 6 and 7 satellites for all pixels between nadir and the extreme view angles are presented. The NOAA 6 data were used to estimate the areas of several lakes, with an accuracy within 5%. Sources of error are discussed

Resonant relativistic corrections and the A_y problem

We study relativistic corrections to nuclear interactions caused by boosting the two-nucleon interaction to a frame in which their total momentum does not vanish. These corrections induce a change in the computed value of the neutron-deuteron analyzing power A_y that is estimated using the plane-wave impulse approximation. This allows a transparent analytical calculation that demonstrates the significance of relativistic corrections. Faddeev calculations are however needed to conclude on the A_y puzzle.Comment: 8 pages, 2 figures, minor addition, to appear in Phys. Rev.

Neutral mass spectrometer measurements in the shuttle bay environment

A neutral mass spectrometer, flown as part of the Induced Environment Contamination Monitor (IECM), is briefly described. Results from STS-2, -3, -4, and Spacelab 1 are qualitatively summarized. The gases observed were, for the most part, those with molecular weights below 45 amu with sources attributable to instrument background, shuttle-induced environment, and the ambient atmosphere. The most abundant gases were H2O, N2, and He. Heavier gases consisted primarily of fluorocarbons

Multiple anode arc lamp system

A high-intensity xenon arc lamp having a plurality of separate anodes axially disposed in a symmetrical pattern which spaced a discharge gap from a common cathode is presented

Indicator providing continuous indication of the presence of a specific pollutant in air

A continuous HCl in-air indicator was developed which consists of a tube-like element with an inlet end through which a continuous stream of air containing HCl enters. The air flows downstream from the inlet end and exits the element's outlet end. Positioned between the element's inlet and outlet ends are first and second spaced apart photoelectric units, which are preferably positioned adjacent the inlet and outlet ends, respectively. Ammonia gas is injected into the air, flowing through the element, at a position between the two photoelectric units. The ammonia gas reacts with the HCl in the air to form ammonium chloride particles. The difference between the outputs of the two photoelectric units is an indication of the amount of HCl in the air stream

SRC seal testing

Small venthole drilled in semisealed silicon-controlled rectifier (SCR) cavity eliminates entrapped helium. Although these devices show slightly greater leak than those before lead installation, it is now possible to distinguish device with good hermetic seal from defective one

Static-pressure contours in the blade passage at the tip of several high Mach number rotors

Static pressure contours of turbine rotor blade tips at high Mach number

Legibility of electroluminescent instrument panels investigated

Legibility studies of several EL /electroluminescent/ displays correlate reading time and accuracy with number size, stroke/width ratio, indicia size, pointer width, contrast, ambient illumination, and color background and and contrast. Human factor criteria established on non-EL displays may not apply to EL displays