scholarly journals The Analysis of Dielectric Constant, Loss Factor and Q-Factor of Selected Fruits at Microwave Frequency Range

2020 ◽  
pp. 57-66
Author(s):  
J. T. Ikyumbur ◽  
A. A. McAsule ◽  
N. S. Akiiga ◽  
Z. E. Andrawus ◽  
S. T. Kungur
Keyword(s):  
Dielectric Constant ◽  
Dielectric Loss ◽  
Loss Factor ◽  
Microwave Frequency ◽  
Dielectric Loss Factor ◽  
Q Factor ◽  
Frequency Range ◽  
Temperature Changes ◽  
Problem Solving Environment ◽  
Lower Frequencies

The dielectric constant, dielectric loss factor and Q-Factor of orange, red and green apples were studied at Microwave frequency range. An algorithm was written using the Debye equations and the interactive problem-solving environment of Maple-18 was used to generate results for the dielectric constant, loss factor and quality factor. The variation in the dielectric constant, loss factor and Q-factor as both frequency and temperature changes respectively within   and  range were shown graphically. The dielectric constant of all the fruits were higher at lower frequencies, it then decreases continuously as frequency increases. On the other hand, the loss factor of this fruits were small at lower frequencies but increased to its peak before decreasing continuously for all temperatures. Interestingly, the fruits’ Q-Factor were higher at lower frequencies and temperatures but decreases rapidly as the frequency increases. The contribution of the space charge, orientation, ionic and electronic polarizations to the dielectric constant, dielectric loss factor and Q-Factor of these fruits at lower frequency and higher frequency were discussed. The effect of the excess sugar and water content on the dielectric constant, loss factor and Q-Factor attributed to the appearance of vibrational peaks was also discussed. This work hereby provides a guidance in developing new microwave processes.

Study on the Dielectric Properties of Biomass Material of Tobacco Stems

2013 ◽  
Vol 634-638 ◽  
pp. 2570-2578 ◽  
Author(s):  
Wen Hua Zi ◽  
Xiao Long Zhang ◽  
Lan Wang ◽  
Jin Hui Peng ◽  
Lin Chen
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Dielectric Loss ◽  
Moisture Content ◽  
Loss Factor ◽  
Microwave Frequency ◽  
Dielectric Loss Factor ◽  
Dipolar Relaxation ◽  
Genetic Characteristics ◽  
Position Location

An Agilent E4980A precision the LCR meter was used to estimate the effect of frequency, moisture content, position, location and variety on dielectric properties for biomass material of tobacco stems at microwave frequency of 2MHz. The dielectric properties of tobacco stems were significantly affected by frequency and moisture content. Both dielectric constant and dielectric loss factor rapidly declined first and then slowed with increasing frequency at lower moisture content. Increasing the moisture content, dielectric constant increased with the increasing frequency by orders of magnitude, while dielectric loss factor increased first and then decreased with dielectric relaxation emerging, where the dipolar relaxation frequency and the max of the dielectric loss factor also increased. Dielectric properties of the biomass material of tobacco stem were also affected by position, location and variety to some degree. The dielectric properties variation of K326 and Yun 87 was similar to each other which reflected their same genetic characteristics. At the frequency of 2MHz, dielectric constant and dielectric loss factor were mainly at 50-100 and 0.005-0.020, respectively.

Microwave Nondestructive Sensing of Moisture Content and Water Activity of Almonds

2021 ◽  
Vol 64 (4) ◽  
pp. 1373-1379
Author(s):  
Samir Trabelsi
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Dielectric Loss ◽  
Moisture Content ◽  
Bulk Density ◽  
Water Activity ◽  
Free Space ◽  
Loss Factor ◽  
Dielectric Loss Factor ◽  
List Type

HighlightsMoisture and water activity were determined nondestructively and in real time from measurement of dielectric properties.Moisture and water activity calibration equations were established in terms of the dielectric properties.Situations in which bulk density was known or unknown were considered.SEC ranged from 0.41% to 0.68% for moisture and from 0.02 to 0.04 for water activity.Abstract. A method for rapid and nondestructive determination of moisture content and water activity of granular and particulate materials was developed. The method relies on measurement of the dielectric constant and dielectric loss factor at a single microwave frequency. For the purpose of illustration, the method was applied to predicting the moisture content and water activity of almond kernels. A free-space transmission technique was used for accurate measurement of the dielectric properties. Samples of Bute Padre almond kernels with moisture content ranging from 4.8% to 16.5%, wet basis (w.b.), and water activity ranging from 0.50 to 0.93 were loaded into a Styrofoam sample holder and placed between two horn-lens antennas connected to a vector network analyzer. The dielectric properties were calculated from measurement of the attenuation and phase shift at 8 GHz and 25°C. The dielectric properties increased linearly with moisture content, while they showed an exponential increase with water activity. Situations in which the bulk density was known and unknown were considered. Linear and exponential growth regressions provided equations correlating the dielectric properties with moisture content and water activity with coefficients of determination (r2) higher than 0.96. Analytical expressions of moisture content and water activity in terms of the dielectric properties measured at 8 GHz and 25°C are provided. The standard error of calibration (SEC) was calculated for each calibration equation. Results show that moisture content can be predicted with SECs ranging from 0.41% to 0.68% (w.b.) and water activity with SECs ranging from 0.02 to 0.04 for almond kernel samples with water activity ranging from 0.5 to 0.9 and moisture contents ranging from 4.8% to 16.5% (w.b.). Keywords: Bulk density, Dielectric constant, Dielectric loss factor, Free-space measurements, Loss tangent, Microwave frequencies, Moisture content, Water activity.

Dielectric Properties of Eucalyptus urophylla Under an Ultra-Wide Frequency Range

2020 ◽  
Vol 12 (8) ◽  
pp. 1236-1241
Author(s):  
He Xia ◽  
Wang Yong ◽  
Li Yunyan ◽  
Wei Yanqiang ◽  
Quan Peng ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
Dielectric Loss ◽  
Dielectric Permittivity ◽  
Loss Factor ◽  
Wide Frequency Range ◽  
Dielectric Loss Factor ◽  
Regression Equations ◽  
Eucalyptus Urophylla ◽  
Frequency Range ◽  
Tangential Directions

Dielectric properties of Eucalyptus urophylla wood were measured by using a network analyzer over an ultrawide frequency range between 0.2 GHz and 20 GHz. The effects of moisture content (MC), temperature and frequency on the dielectric permittivity and the dielectric loss factor of Eucalyptus urophylla were investigated along different grain directions. The results showed that the dielectric permittivity along with the dielectric loss factor increased significantly with the elevation in MC. At the frequency of 2380 MHz with the MC increasing from 0% to 100%, the dielectric permittivity along different grain directions (including longitudinal, radial and tangential directions) increased by 180%, 110% and 112%, respectively, while the loss factor along these three directions increased by 1642%, 3703% and 5058%, respectively. In addition, the increase in dielectric properties of Eucalyptus urophylla wood was determined with the temperature elevating. When the temperature elevated from 20 °C to 140 °C, the dielectric permittivity at 2380 MHz along the longitudinal, radial and tangential directions, increased by 19%, 14% and 15%, respectively, while the loss factor increased by 133% at most. As the radio frequency increased, the dielectric permittivity of wood decreased. Regression equations satisfactorily described the dielectric properties of wood along different grain directions with different moisture contents.

scholarly journals Dielectric properties of zinc sulfide concentrate during the roasting at microwave frequencies

2017 ◽  
Author(s):  
Guangjun He ◽  
Shiwei Li ◽  
Kun Yang ◽  
Jian Liu ◽  
Peng Liu ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Dielectric Loss ◽  
Zinc Sulfide ◽  
Apparent Density ◽  
Loss Tangent ◽  
Loss Factor ◽  
Microwave Energy ◽  
Dielectric Loss Factor ◽  
Sulfide Concentrate

Microwave technology has a potential application in the extraction of zinc from sulphide ores, knowledge of the dielectric properties of these ores plays a major role in the microwave design and simulation for any process. The dielectric properties of zinc sulfide concentrate for two different apparent densities—1.54 and 1.63 g/cm3—have been measured by using the resonance cavity perturbation technique at 915 and 2450 MHz during the roasting process for the temperature ranging from room temperature to 850 °C. The variations of dielectric constant, the dielectric loss factor, the dielectric loss tangent and the penetration depth with the temperature, frequency and apparent density have been investigated numerically. The results indicate that the dielectric constant increases as the temperature increases and temperature has a pivotal effect on the dielectric constant, while the dielectric loss factor has a complicated change and all of the temperature, frequency and apparent density have a significant impact to dielectric loss factor. Zinc sulfide concentrate is high loss material from 450 to 800 °C on the basis of theoretical analyses of dielectric loss tangent and penetration depth, its ability of absorbing microwave energy would be enhanced by increasing the apparent density as well. The experimental results also have proved that zinc sulfide concentrate is easy to be heated by microwave energy from 450 to 800 °C. In addition, the experimental date of dielectric constant and loss factor can be fitted perfectly by Boltzmann model and Gauss model, respectively.

scholarly journals Dielectric and Conductivity Properties of Some Wood Composites

2016 ◽  
Vol 8 ◽  
pp. 51-60
Author(s):  
K.Ch. Varada Rajulu ◽  
B.N. Mohanty
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Dielectric Loss ◽  
Low Temperature ◽  
Temperature Region ◽  
Loss Factor ◽  
Wood Composites ◽  
Frequency Range ◽  
Increasing Temperature ◽  
Coaxial Probe

This study presents the dielectric and conductivity properties as function of temperature and frequency of wood based composites. These properties were measured by an open-ended coaxial probe at frequency range between 100 kHz to 100MHz, temperature from 30OC to 200OC which is fully computer interfaced. It has been observed that dielectric constant (ε') and dielectric loss factor (ε") increase with increasing temperature and decrease with increasing frequency. At low temperature region, the conductivity depends significantly on the frequency. However, with the increase in temperature dielectric relaxation takes place and the dependency of the conductivity on frequency get reduced. The patterns of variation were established for the studied specimens and discrepancies were discussed. The study of dielectric properties will help in improving the drying, heating and gluing processes of wood and wood based products.

EFFECT OF DIELECTRIC PROPERTY OF HYDROUS DISPERSOID ON ELECTRORHEOLOGY

1996 ◽  
Vol 10 (23n24) ◽  
pp. 2849-2855 ◽  
Author(s):  
Akiko KAWAI ◽  
Kunio UCHIDA ◽  
Kunio KAMIYA ◽  
Akihiro GOTOH ◽  
Satoshi YODA ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Dielectric Property ◽  
Dielectric Loss ◽  
Water Content ◽  
Loss Factor ◽  
Free Water ◽  
Relaxation Frequency ◽  
Dielectric Loss Factor ◽  
Silicon Oil

The effect of the dielectric property was investigated of titania and microcrystalline cellulose particles dispersed in a silicon oil on Electrorheology(ER). A commom understanding of the mechanism of ER is the electrical interaction by the interfacial polarization of dispersed particles. Block et al. reported the relaxation frequency of ER fluids, i. e. the rate of polarization, was very important to have an appreciable ER effect. We found that the free water on the cellulose and the titania particles dispersed in the silicon oil, which is respectively dehydrated below the temperature of ca. 110 and 300 degree centigrade, was necessary for an appreciable ER effect. The relation was measured between the water content and the dielectric properties such as dielectric constant ε ’ and dielectric loss factor ε ", as the water adsorbed on the particles was estimated to alter the dielectric properties of the ER fluid. Both the dielectric constant and the relaxation frequency, which is defined by the applied frequency for a peak of the dielectric loss factor, increased with the increase of the water content The relation was discussed between the ER effect and the dielectric properties.

scholarly journals Detection of biodegradation degree of sludge using dielectric measurement

2018 ◽  
Vol 6 (1-2) ◽  
pp. 108-112
Author(s):  
Sándor Beszédes ◽  
Katalin Papp-Sziládi ◽  
Gábor Keszthelyi-Szabó ◽  
Cecília Hodúr
Keyword(s):  
Dielectric Constant ◽  
Organic Matter ◽  
Dielectric Properties ◽  
Dielectric Loss ◽  
Loss Factor ◽  
Dielectric Loss Factor ◽  
Dielectric Measurement ◽  
Energetic Efficiency ◽  
Dielectric Parameters ◽  
Polymeric Structure

Pre-treatments applied before biological sludge utilization technologies aim to modify the sludge structure for enhanced disintegration degree and biodegradability. Among the thermal pre-treatments methods, microwave irradiation is suitable to degrade the polymeric structure of sludge, and to increase the solubility of organic matters. Energetic efficiency of microwave heating is mainly determined by the dielectric properties, such as dielectric constant and dielectric loss factor. Dielectric properties are influenced by the frequency, temperature; composition and consistency of irradiated material, state and bond of water etc. Therefore, physicochemical changes of sludge structure; e.g. hydrolysis of macromolecules, degradation of cell wall of microorganisms, aggregation of particles; contribute to the change of dielectric parameters, as well. In our work we investigated the correlation between the dielectric parameters and structural change and biodegradability indicators. In the case of municipal wastewater, the change of organic matter removal efficiency during wastewater purification technology at a wastewater treatment plant can be detected by the change of dielectric constant. Results related to sludge processing show, that change of organic matter solubility and aerobic biodegradability correlate the change of dielectric loss factor and dielectric constant. With the degradation of polymeric structure of sludge matrix and decomposition of macromolecules caused by thermal effects or chemical pre-treatments led to increased mobility of ions and enhanced polarization of molecules. These effects led to increased dielectric constant and loss factor, what make possible to pre-indicate the efficiency of sludge pre-treatment processes by an in line and real time measurement method.

HIGH-FREQUENCY DIELECTRIC BEHAVIOR OF INDIUM AND CHROMIUM SUBSTITUTED Mg–Mn FERRITES

2010 ◽  
Vol 24 (15) ◽  
pp. 1657-1667 ◽  
Author(s):  
A. LAKSHMAN ◽  
P. S. V. SUBBA RAO ◽  
K. H. RAO
Keyword(s):  
Dielectric Constant ◽  
Dielectric Loss ◽  
High Frequency ◽  
Loss Factor ◽  
Space Charge Polarization ◽  
Dielectric Behavior ◽  
Dielectric Loss Factor ◽  
Dc Resistivity ◽  
Low Dielectric ◽  
Tan Δ

Dielectric properties such as DC resistivity (ρ), dielectric constant (ε) and dielectric loss factor ( tan δ) have been measured for Mg 0.9 Mn 0.1 In x Fe 2-x O 4 and Mg 0.9 Mn 0.1 Cr y Fe 2-y O 4 at room temperature. The composition dependence of ρ, ε and tan δ and the frequency dependence of ε and tan δ are presented in this paper. The resistivity increases while the dielectric constant decreases with increasing concentrations of indium and chromium ions. The dielectric loss factor at 100 kHz increases with composition for the samples 0.1 ≤ x ≤ 0.9 and 0.1 ≤ y ≤ 0.7. The dielectric constant for a given sample decreases with increasing frequency showing the normal dielectric behavior. The values of dielectric loss factor have been found to increase with frequency for the samples corresponding to x or y = 0.1 to 0.5; while other samples showed abnormal dielectric behavior. The observed variations in ρ are explained by Verwey's hopping mechanism while the variations in ε and tan δ with composition and frequency are explained by space charge polarization using Koop's theory. Higher values of DC resistivity and low dielectric losses suggest that the prepared materials have great potential for microwave and high-frequency applications.

scholarly journals Dielectric Spectroscopy of Grape Juice at Microwave Frequencies

2015 ◽  
Vol 29 (2) ◽  
pp. 239-246 ◽  
Author(s):  
Ravika Vijay ◽  
Ritu Jain ◽  
Krishna S. Sharma
Keyword(s):  
Dielectric Constant ◽  
Dielectric Loss ◽  
High Frequency ◽  
Loss Factor ◽  
Low Frequency ◽  
Grape Juice ◽  
Angular Frequency ◽  
Dielectric Loss Factor ◽  
High Frequency Region ◽  
Different Temperatures

Abstract The complex permittivity of fresh juice of two cultivars of grapes, Sultania (green grapes) and Black Monukka (black grapes) was measured in terms of the dielectric constant and dielectric loss factor over the frequency range from 1 to 50 GHz and at temperatures ranging from 30 to 60°C, by using the PNA network analyzer model E8364C and open ended coaxial probe 85070E. The Cole-Cole plots and dielectric constant vs. (angular frequency) dielectric loss factor and dielectric constant vs. dielectric loss factor/(angular frequency) regression lines at different temperatures were used in Debye approximation to predict relaxation frequency of molecules for the two cultivars of grapes in the low frequency and high frequency limits, respectively. It was observed that the acidic character of green grapes is responsible for the large amplitude vibrational peaks in dielectric loss factor - frequency curves, in the high frequency region at higher temperatures. On the other hand, excess of sugar in black grapes suppresses the activity of water molecules, thereby suppressing the vibrational peaks at higher frequencies. Different relaxation frequencies found for the two cultivars of grapes suggest that they have different molecular structure.

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