Dielectric Moisture Sensor for Cereal Grains and Soybeans
2001
Lawrence, K.C. | Funk, D.B. | Windham, W.R.
A shielded parallel-plate moisture sensor was designed, calibrated, and verified to sense the wet-basis moisture content of wheat (hard red winter, hard red spring, soft red winter, hard white, soft white, and durum), yellow-dent field corn, long- and medium-grain rough rice, and soybeans. The sensor uses complex reflection coefficient measurements and sample weight to predict the moisture content of static samples at room temperature (~22 ° C) with a sample volume of 850 cm 3 . Multivariate analysis techniques were used to eliminate outliers. The sensor was calibrated with samples of differing lots, grown throughout the U. S. in 1997. The standard error of calibration and the coefficient of determination ranged from 0.37% mc and 0.986 for yellow-dent field corn to 0.09% mc and 0.999 for durum wheat, respectively. The sensor was independently verified with 1998 crop-year samples with bias and standard deviation values reported for all commodities except rice (1997 and 1998 crop years combined for calibration). Generally, the sensor had a similar bias and lower standard deviation compared to commercial moisture meter readings for similar populations and moisture ranges.
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