Article

Effects of "natural" water and "added" water on prediction of moisture content and bulk density of shelled corn from microwave Dielectric properties

U. S. Department of Agriculture, Agricultural Research Service, Richard B. Russell Agricultural Research Center, Athens, GA 30604-5677, USA.
The Journal of microwave power and electromagnetic energy: a publication of the International Microwave Power Institute (Impact Factor: 0.5). 01/2010; 44(2):72-80.
Source: PubMed

ABSTRACT

Dielectric properties of samples of shelled corn of "natural" water content and those prepared by adding water were measured in free space at microwave frequencies and 23 degrees C. Results of measurements of attenuation, phase shift and dielectric constant and loss factor at 9 GHz show no difference between the samples with "natural" water and those in which water was added artificially. Bulk densities and moisture contents predicted from calibration equations expressed in terms of dielectric properties of both natural and added water samples agreed closely, and standard errors were less than 1% for moisture content and relative error for bulk density was less than 5%.

Download full-text

Full-text

Available from: Micah A Lewis, Sep 21, 2015
  • Source
    • "The researches on the rapid on-line moisture detection of corn kernels were focused on capacitance measurement [1] [2] [3] and microwave measurement [4] [5] [6] [7] . "
    [Show abstract] [Hide abstract]
    ABSTRACT: Moisture content of corn directly affects its quality and storage time, and the rapid on-line detection of the moisture content of corn ears not threshed or in vivo in the fields is required. Because of the special shape of corn ear, the rapid, low cost and non-destructive bioelectrical impedance measurement is more suitable for its moisture content detection. Using the four-electrode method with the Agilent E4980A precision LCR meter, the electrical impedance spectroscopies of the sweet corn ears and waxy corn ears at different moisture contents were acquired. The frequency range of the detection was from 20 Hz to 2 MHz and to enhance the contact, the attached-type electrodes were wrapped in cotton soaked with 0.1% NaCl solution. The impedance data over the frequency range from 300 Hz to 5 kHz were used to obtain the parameters of the bio-impedance Cole-Cole model. The results showed a good linear correlation (coefficient of determination R-2=0.960) between the equivalent parallel resistance R-infinity of sweet corn ear and the moisture content value determined by standard chemical method. The research proved that the bioelectrical impedance spectroscopy can be used for detecting the moisture content of corn ear.
    Full-text · Article · Jan 2016 · International Journal of Agricultural and Biological Engineering
  • Source
    • "This includes open coaxial probe, transmission line, free space and resonant cavity or cavity perturbation method [32]. Typically , the choice of dielectric property measuring technique depends on the nature of material (solid, liquid, powder), accuracy, material properties, sample size, contact or non-contact, frequency and temperature [32] [33]. Cavity perturbation technique is able to measure the dielectric properties for the most commonly used industrial frequencies (400–3000 MHz), in the temperature range from room to about 1400 °C [31], the size of the sample is small, and can handle low loss material [14] such as biomass, and therefore it was selected in this study. "
    [Show abstract] [Hide abstract]
    ABSTRACT: The knowledge of the dielectric property is essential to design and develop microwave technology for processing biomass materials. This paper focuses on the measurement of dielectric properties of three different Saudi Arabian date palm biomass (seed, leaf and stem) from room temperature to ∼800 °C and at six different frequencies (397–2986 MHz) using a cavity perturbation method. The result showed that all date palm biomass samples were poor microwave absorbers from room temperature till 500 °C. The dielectric constant and loss factor dropped slightly in the drying region due to removal of moisture and was almost constant in pyrolysis region. However, a significant increase in dielectric constant and loss factor occurred in temperature between 500 and 750 °C, except for leaf biomass. Penetration depth and tangent loss had an opposite behavior with the rise in temperature. In conclusion, the dielectric properties might not only depend on the temperature and frequency but also on the physical and chemical characteristics of the biomass material. For instance, it was interesting to know that date leaf showed a sharp decrease in loss factor from temperature 475 °C, which was opposite to that observed in case of date seed and stem. The data can be very useful in designing, modeling and simulation of microwave processing system for date palm biomass.
    Full-text · Article · Dec 2015 · Fuel