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Efficacy of the Landau-Lifshitz, Looyenga Mixture Equation for Density-Correcting Dielectric Measurements of Yellow-Dent Corn Subjected to Vibration and Pressure

Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan

Citation:  Paper number  026038,  2002 ASAE Annual Meeting . (doi: 10.13031/2013.10547) @2002
Authors:   Biborka Gillay, David B. Funk
Keywords:   Dielectric, grain, moisture, pressure, vibration, mixture equations

The dielectric characteristics of yellow-dent field corn were measured over the frequency range of 31 Hz to 28.1 MHz. The density of the grain samples were altered by settling and by applying prescribed levels of force to the upper surface of the grain in the dielectric test cell. Two different test cell shapes, coaxial and parallel-plate, were evaluated. The Landau-Lifshitz, Looyenga dielectric mixture equation was applied to the dielectric data to determine whether it is capable of correcting for density differences caused by settling and pressure separately and in combination. Density changes due to pressure were found to cause profoundly different changes in dielectric characteristics than density changes due to settling. The Landau-Lifshitz, Looyenga equation was generally successful in correcting for density differences due to settling, but it was less effective in dealing with density differences due to pressureparticularly with high moisture corn and at low measurement frequencies where conductivity effects are more important.

Tests with a coaxial cell whose center electrode did not extend to the top of the outer coaxial electrode exhibited special problems with density correction. Analysis of this case pointed out the necessity of measuring the actual density of the grain as positioned in the dielectric test cell to achieve precise density corrections.

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