An experimental investigation has been conducted to determine the iffect riffi lm thickness on the frict ion coefficient of solid powdered lubricants, applied as thin films on the mild steelspecimens. Curves representing the coefficient offriction f or various film thicknesses, as well as the tabulated data are given. The results are discussed and compared to those theoretically conceivable using the relationship rif Bowden and Tabor and that rif Rabinowic<:.. Solidfi lms of graphite, molybdenum disulphide and calcium fluoride with a thickness range rif 0.0002 to 0.0008 in. were used. It has been concluded that, f or the solid lubricants tested, lhe coefficient riffriction is dependent upon the film thickness. The Theory ofAdhesion by Bowden and Tabor and the mathematical relationship by Rabino uncr do not adequately explain the variation in the coefficient offriction as the film thickness vanes.

The trophic characterization of lakes has been intermittently monitored in recent years with data generated from satellite and aircraft spectral scanners. Each of these methods used “ground truth” (lake sampling data) to establish a correlation between scanner‐recorded radiance values and a trophic index for each lake (or portion of a lake). The approaches varied in their processing of the digital imagery, as well as in the development of trophic indices. Currently, several states employ varying spectral imagery techniques to develop lake classifications to satisfy the requirements of Section 314 of Federal Water Pollution Control Act. These variations have created a need for developing a uniform, tested approach for use by states and EPA for the description of lake trophic state from multispectral imagery. The current state and the use of multispectral data and technology to determine lake trophic indices is assessed in this paper.

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