Moisture content and bulk density prediction using dielectric properties for switchgrass and corn stover
Dielectric measurements between 0.1 to 10 MHz were obtained using an HP 4192A impedance analyzer for switchgrass and corn stover. For each material, the measurements were obtained at four moisture content levels and three bulk densities. Dielectric properties of these materials could be calculated based on admittance readings and each variable was significant for dielectric constant and loss factor measurements. Dielectric variables were used to predict moisture content and bulk density for both materials. For switchgrass, moisture content was predicted with R2 = 0.94 and RMSE = 0.052%, while for density was predicted with R2 = 0.85 and RMSE = 0.0323 g/cm3. For corn stover, moisture content was predicted with R2 = 0.90 and RMSE = 0.0315%, whereas, for bulk density, the regression model had a R2 =0.87 and RMSE = 0.0068 g/cm3. The results indicated that dielectric measurements have good potential for predicting moisture content and bulk density although further investigation is required for a wider range of frequencies, moisture content, and bulk density levels.