Displacements Schemes for Obtaining the Frequency Dependence on the Cottonseeds
Moisture

The mathematic model of the high frequency moisture meter for cottonseeds has been constructed, in which the studying material as a complex dielectric installing in an electric field is represented. The displacement scheme which includes capacity between electrodes and also capacities and resistors corresponding to different polarization types has been presented. 4 variants of displacement schemes which describe approximately the dependence of angle tangency of dielectric losses on the electromagnet field frequency using in the measuring device have been considered. It has been shown that the simplest two element R-C scheme connected parallel corresponds to the closest real description of measuring object in frequencies range from 105 up to 108 Hertz.

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A mathematical model of the high frequency moisture meter for cottonseeds based on the displacements schemes

Metrologiya ◽

10.32446/0132-4713.2020-3-53-70 ◽

2020 ◽

pp. 53-70

Author(s):

Tulkun Z. Nasirov ◽

Patxulla R. Ismatullayev ◽

Hamdam Sh. Jabborov

Keyword(s):

High Frequency ◽

Mathematic Model ◽

Field Frequency ◽

Measuring Device ◽

Qualitative And Quantitative ◽

Urgent Task ◽

Moisture Meter ◽

Cotton Seeds ◽

Quantitative Indicators ◽

Main Factor

An overview of high-frequency methods for measuring and controlling humidity of various materials is given. Humidity of cotton seeds is the main factor affecting their qualitative and quantitative indicators in the technological processes of storage, transportation, processing. Therefore, measuring the humidity of cotton seeds directly in the technological process is an urgent task. The mathematic model of the high frequency moisture meter for cotton grains has been constructed, in which the studying material as a complex dielectric installing in an electric field is represented. The displacement scheme which includes capacity between electrodes and also capacities and resistors corresponding to different polarization types has been presented. 4 variants of displacement schemes which describe approximately the dependence of angle tangency of dielectric losses on the electromagnet field frequency using in the measuring device have been considered. It has been shown that the simplest two elements RC-scheme connected parallel corresponds to the closest real description of measuring object in frequencies range from 105 up to 108 Hertz.

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Formation of Regular Domain Structures in Quenched Ferroelectrics Under the Influence of an External High-frequency Electric Field

Nanoscience &Nanotechnology-Asia ◽

10.2174/2210681208666180626124705 ◽

2019 ◽

Vol 9 (3) ◽

pp. 344-352 ◽

Cited By ~ 4

Author(s):

L.I. Stefanovich ◽

O.Y. Mazur ◽

V.V. Sobolev

Keyword(s):

Lithium Niobate ◽

Electric Field ◽

Domain Structure ◽

High Frequency ◽

Evolution Equations ◽

Regular Domain ◽

Field Frequency ◽

Domain Structures ◽

Alternating Electric Field ◽

Lithium Niobate Crystals

Introduction: Within the framework of the phenomenological theory of phase transitions of the second kind of Ginzburg-Landau, the kinetics of ordering of a rapidly quenched highly nonequilibrium domain structure is considered using the lithium tantalate and lithium niobate crystals as an example. Experimental: Using the statistical approach, evolution equations describing the formation of the domain structure under the influence of a high-frequency alternating electric field in the form of a standing wave were obtained. Numerical analysis has shown the possibility of forming thermodynamically stable mono- and polydomain structures. It turned out that the process of relaxation of the system to the state of thermodynamic equilibrium can proceed directly or with the formation of intermediate quasi-stationary polydomain asymmetric phases. Results: It is shown that the formation of Regular Domain Structures (RDS) is of a threshold character and occurs under the influence of an alternating electric field with an amplitude less than the critical value, whose value depends on the field frequency. The conditions for the formation of RDSs with a micrometer spatial scale were determined. Conclusion: As shown by numerical studies, the RDSs obtained retain their stability, i.e. do not disappear even after turning off the external electric field. Qualitative analysis using lithium niobate crystals as an example has shown the possibility of RDSs formation in high-frequency fields with small amplitude under resonance conditions

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Dielectric losses under heat treatment of dispersed media

Proceedings of Irkutsk State Technical University ◽

10.21285/1814-3520-2020-6-1223-1231 ◽

2021 ◽

Vol 24 (6) ◽

pp. 1223-1231

Author(s):

M. Yu. Buzunova

Keyword(s):

Heat Treatment ◽

Dielectric Loss ◽

Electric Field ◽

External Electric Field ◽

Dielectric Losses ◽

Loss Angle ◽

Field Frequency ◽

Dielectric Characteristics ◽

Dielectric Loss Angle ◽

Electric Field Frequency

The purpose of the paper is to study the dependence of dielectric losses of mechanically activated grain crops on example of wheat under heat treatment on temperature and external electric field frequency as well as to examine the effect of particle size of fine grain samples on grain electrophysical characteristics and dielectric losses. Experimental samples of dispersed systems with particle sizes in the range from 50 to 1000 μm are prepared by the method of mechanical activation. The temperature dependence of the dielectric loss angle tangent is measured using the dielectric method over a wide frequency range. The dependence of the dielectric loss angle tangent tgδ of mechanically activated wheat samples with the different degrees of particle dispersion in a wide temperature range from 20°C to 250°C with a heating rate of 0.7 deg/min is studied. It is found out that the external electric field frequency varies in the range from 25 Hz to 106 Hz. Electric capacitance and conductivity are measured using an E7-20 immitance meter and a specially designed measuring cell. Dielectric characteristics are calculated. Experimental data are presented in the form of graphs and diagrams. We have determined the correlation of the tangent of the dielectric loss angle tgδ with the frequency of the external electric field and temperature, which is most characteristic for fine samples. The most finely dispersed samples with a particle size of less than 50 microns are shown to have high electrical activity. Increase in the dielectric permittivity and the tangent of the dielectric loss angle is most noticeable at the frequencies below 100 Hz. The study of dielectric characteristics allows to choose an effective energy-saving drying mode of the crop under study.

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