Performance analysis of RF dielectric models for density-independent estimation of moisture content in sorghum

Dielectric properties of papaya seeds from 75 kHz to 5 MHz

“…The C p and G values were measured at 75, 80, 85, 90, 95, 100, 200, 300, 400 and 500 kHz, and 1, 2, 3, 4 and 5 MHz. The ε' and ε" values were calculated according to the methodology described by Moura et al (2013). Automatic data collection was performed using a computer with an HP-IB interface card and LabVIEW (National Instruments) control software.…”

“…throughout the paper) at low temperatures. Moura et al (2013) emphasized the importance of the on-line moisture content sensors installed in the storage environment that would function as a method of quality control of the product in storage, without the need to destroy the samples, as is the case with the oven drying method. The on-line moisture content meters of granular agricultural materials are classified as indirect measurement methods because they are based on physical properties that can be correlated with the volumetric concentration of water in the seed sample.…”

“…This focus is partly due to the decrease or elimination of problems related to ionic conductivity, which allows the study of a wider range of moisture contents. However, researchers have also demonstrated that it is possible to indirectly measure the seed moisture content (generally up to 23%), regardless of the bulk density variations of the sample, using radiofrequencies (Funk et al, 2007;Moura et al, 2013). This is due to the fact that, with the appropriate choice of the size and shape of electrodes, it is possible to measure the moisture content using a considerable volume of seeds, resulting in a more representative measurement.…”

“…The investigation of the variation of ε' and ε" as a function of the moisture content (M), along with bulk density (ρ) and the electric field oscillation frequency (F) makes it possible to determine the ranges or values of these variables, which will compose the dielectric model M = f [ε' (F) , ε" (F) ] that is independent of the variation of ρ. In fact, studies on the dielectric properties of seeds, such as rice (Prasad and Singh, 2007), maize (Cseresnyés et al, 2013;Sacilik and Colak, 2010), sorghum (Moura et al, 2013) and wheat (Berbert and Stenning, 1996); oilseeds, such as peanuts (Boldor et al, 2004), flax seed (Sacilik et al, 2006) and soybean (Trabelsi and Nelson, 2006); legumes, such as beans (Berbert et al, 2002); coffee (Berbert et al, 2001); and wheat flour mixed with oat meal (Łuczycka et al, 2013) have been performed over the last decades, using both microwave frequencies and radiofrequencies.…”

Hyper-Heuristic Capacitance Array Method for Multi-Metal Wear Debris Detection

“…Capacitive sensors can detect the change of dielectric constants between plates. Designed sensor arrays are used to measure the voltage between sensitive electrodes, and an appropriate image reconstruction algorithm is used to construct the medium distribution in the target field [15,16,17]. The dielectric constants of metallic materials differ by more than seven orders of magnitude from those of bubbles, water, oil, and other non-metallic materials [18].…”