Dielectric Properties of Various Ranks of Coal and Numerical Modeling Under Electromagnetic Irradiation

1990 ◽  
Vol 189 ◽  
Author(s):  
I. Chatterjee ◽  
M. Misra
Keyword(s):  
Dielectric Properties ◽  
Method Of Moments ◽  
Electromagnetic Waves ◽  
Numerical Technique ◽  
Free Water ◽  
Microwave Drying ◽  
Network Analyzer ◽  
Frequency Range ◽  
Absorbed Energy ◽  
Finite Difference Technique

ABSTRACTThe dielectric properties of different ranks of Argonne Premium coal samples have been measured using an automated network analyzer system in the frequency range 0.3MHz to 3GHz. These measurements indicate that the inherent moisture present in the various ranks ofcoal has dielectric properties which are different from that of free water. The dielectric properties were also observed to increase with the moisture content as well as with the amount of oxygen present in the coal sample. A mixture model was successfully used topredict these dielectric properties.The measured dielectric properties have been incorporated into numerical calculations ofthe distribution of absorbed energy in coal irradiated with electromagnetic waves. The numerical technique used is the Method of Moments. Subsequently, the temperature distribution obtained in the coal is evaluated using a Finite Difference technique to solve the heat conduction equation. These calculations should prove very useful in the microwave drying of coal where it is difficult to monitor the temperature using probes.

Preparation of polypyrrole/polyester-cotton composites and a study of their dielectric properties and conductivity

2020 ◽  
pp. 004051752096569
Author(s):  
Yuanjun Liu ◽  
Yi Wang
Keyword(s):  
Dielectric Properties ◽  
Electromagnetic Waves ◽  
Surface Resistance ◽  
In Situ Polymerization ◽  
Sodium Dodecyl ◽  
Sodium Dodecyl Benzene Sulfonate ◽  
Benzene Sulfonate ◽  
Frequency Range ◽  
Doping Agent ◽  
Dodecyl Benzene Sulfonate

Polypyrrole/polyester-cotton composites were prepared using pyrrole as the monomer, adopting an in situ polymerization on the plain polyester-cotton fabric. The influence of the pyrrole concentration, type and concentration of doping agents on the dielectric properties and conductivity of polypyrrole/polyester-cotton composites were investigated using the method of control variables. The results show that within the frequency range 0.01–1.0 GHz, and for concentrations of pyrrole monomers of 0.3, 0.6, 0.9, 1.2 and 1.5 mol/L, the polypyrrole/polyester-cotton composite had the strongest polarization ability, dissipation ability and absorbing-attenuation ability to electromagnetic waves, and the surface resistance was the smallest and conductivity was the best when the pyrrole concentration was 0.9 mol/L. Within the same frequency range, five doping agents were tested, namely sodium dodecyl benzene sulfonate, p-toluenesulfonic acid, ferric chloride, sodium lignosulfonate and camphor sulfonic acid. The composite with sodium dodecyl benzene sulfonate as the doping agent had the strongest polarization ability, dissipation ability and absorbing-attenuation ability to electromagnetic waves, the lowest surface resistance and the strongest conductivity. Finally, within the same frequency range and using doping agent concentrations of 0.1 and 0.2 mol/L, the composite with doping agent concentration of 0.1 mol/L had the strongest polarization ability, dissipation ability and absorbing-attenuation ability.

Broad Band Microwave Dielectric Measurement of Liquids with an Open-Ended Coaxial Probe

2013 ◽  
Vol 333-335 ◽  
pp. 191-198
Author(s):  
Jia Ming Shi ◽  
Quirino Balzano ◽  
Christopher C. Davis
Keyword(s):  
Dielectric Properties ◽  
Broad Band ◽  
Dielectric Measurement ◽  
Network Analyzer ◽  
Frequency Range ◽  
Probe Technique ◽  
Microwave Dielectric ◽  
Coaxial Probe

The principles of the open-ended coaxial probe technique for the measurement of permittivity are described. Measurements of dielectric properties are carried out over a frequency range from 300MHz to 50GHz, with a system comprising an Agilent E8364B network analyzer and a connected 2.2mm diameter open-ended coaxial probe. Water, methanol and salines of 0.1M, 0.2M, 0.6M are used as calibration liquids or liquids to be measured. Measured permittivities are presented and compared with those calculated from the Cole-Cole equation. It is shown that, in order to get good results, the calibration liquid should be similar to the liquid being measured in dielectric properties.

The working standard of the unit of power of electromagnetic waves in the frequency range from 37,5 to 220 GHz

2020 ◽  
pp. 53-58
Author(s):  
A. V. Koudelny ◽  
I. M. Malay ◽  
V. A. Perepelkin ◽  
I. P. Chirkov
Keyword(s):  
Microwave Power ◽  
Electromagnetic Waves ◽  
Primary Standard ◽  
The State ◽  
Frequency Range ◽  
Working Standard ◽  
Extended Frequency Range ◽  
Effective Efficiency ◽  
Extended Frequency ◽  
Good Agreement

The possibility of using bolometric converters of microwave power from the State primary standard of the unit of power of electromagnetic waves in waveguide and coaxial paths GET 167-2017, which has a frequency range from 37,5 to 78,33 GHz, in an extended frequency range up to 220 GHz, is shown. Studies of semiconductor bolometric converters of microwave power in an extended frequency range have confirmed good agreement and smooth frequency characteristics of the effective efficiency factor of the converters. Based on the research results, the State working standard of the unit of power of electromagnetic waves of 0,1–10 mW in the frequency range from 37,5 to 220 GHz 3.1.ZZT.0288.2018 was approved. The technical characteristics of the working standard of the unit of power of electromagnetic oscillations in an extended frequency range from 37,5 to 220 GHz are given.

scholarly journals Simulation and Experimental Study of the Near Field Probe in the Form of a Folded Dipole for Measuring Glucose Concentration

2021 ◽  
Vol 11 (12) ◽  
pp. 5415
Author(s):  
Aleksandr Gorst ◽  
Kseniya Zavyalova ◽  
Aleksandr Mironchev ◽  
Andrey Zapasnoy ◽  
Andrey Klokov
Keyword(s):  
Experimental Measurement ◽  
Glucose Concentration ◽  
Field Experiments ◽  
Near Field ◽  
Vector Network Analyzer ◽  
Human Hand ◽  
Physical Parameters ◽  
Network Analyzer ◽  
Frequency Range ◽  
Average Deviation

The article investigates the near-field probe of a special design to account for changes in glucose concentration. The probe is designed in such a way that it emits radiation in both directions from its plane. In this paper, it was proposed to modernize this design and consider the unidirectional emission of the probe in order to maximize the signal and reduce energy loss. We have done extensive research for both bidirectional and unidirectional probe designs. Numerical simulations and field experiments were carried out to determine different concentrations of glucose (0, 4, 5.3, 7.5 mmol/L). Numerical modeling of a unidirectional probe showed that the interaction of radiation generated by such a probe with a multilayer structure simulating a human hand showed a better result and high sensitivity compared to a bidirectional probe. Further, based on the simulation results, a phantom (physical model) of a human hand was recreated from layers with dielectric properties as close as possible to the properties of materials during simulation. The probe was constructed from a copper tube and matched both the geometric and physical parameters of the model. The experimental measurement was carried out using a vector network analyzer in the frequency range 2–10 GHz. The experimental measurement was carried out using a vector network analyzer in the frequency range 2–10 GHz for the unidirectional and bidirectional probes. Further, the results of the experiment were compared with the results of numerical simulation. According to the results of multiple experiments, it was found that the average deviation between the concentrations was 2 dB for a unidirectional probe and 0.4 dB for a bidirectional probe. Thus, the sensitivity of the unidirectional probe was 1.5 dB/(mmol/L) for the bidirectional one 0.3 dB/(mmol/L). Thus, the improved design of the near-field probe can be used to record glucose concentrations.

Optimization of the microwave drying process for potato chips based on the measurement of dielectric properties

2019 ◽  
Vol 37 (11) ◽  
pp. 1329-1339 ◽  
Author(s):  
GuiYi Luo ◽  
ChunFang Song ◽  
Pu Hongjie ◽  
Zhenfeng Li ◽  
Wanxiu Xu ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
Potato Chips ◽  
Microwave Drying ◽  
Drying Process

Mechanical and Microwave Dielectric Properties of Csf/Si3N4 Composites

2007 ◽  
Vol 546-549 ◽  
pp. 1661-1664
Author(s):  
Xiao Yan Wang ◽  
Fa Luo ◽  
Dong Mei Zhu ◽  
Wan Cheng Zhou ◽  
Hong Huan Wu
Keyword(s):  
Carbon Fibers ◽  
Microwave Dielectric Properties ◽  
Xrd Analysis ◽  
Network Analyzer ◽  
Hot Press ◽  
Frequency Range ◽  
The Real ◽  
Microwave Dielectric ◽  
Hot Press Sintering ◽  
Sintering Method

Csf/Si3N4 composites were prepared by hot-press sintering method using α-Si3N4 power, short chopping carbon-fiber and sintering additives. XRD analysis showed that the α-Si3N4 was almost completely transferred into β-Si3N4. The SEM micrographs of fractured surfaces showed that special network developed by rod-like β- Si3N4 grains. The flexure strength of 590±10MPa, and fracture toughness of 7.94±0.1MPa·m1/2 were achieved for the samples incorporated with 0.5wt% the carbon fibers .The microwave dielectric property of Csf/Si3N4 composites was measured at a frequency range of 8.2~18GHz by E8362B PNA series network analyzer. The real part (ε ′ ) of the permittivity of the Csf/Si3N4 composites increases from 10 to 58 with the rise of the content of carbon fibers in the composites, as well as the imaginary part increases from 0.03 to 98 at frequency of 9.375GHz. A strong frequency dependence of the real part was observed both in X and Ku bands.

INFLUENCE OF La2O3 ADDITIONS ON CHEMICAL DURABILITY AND DIELECTRIC PROPERTIES OF BOROALUMINOSILICATE GLASSES

2012 ◽  
Vol 19 (06) ◽  
pp. 1250062 ◽  
Author(s):  
X. H. ZHANG ◽  
Y. L. YUE ◽  
H. T. WU
Keyword(s):  
Dielectric Properties ◽  
Chemical Durability ◽  
Tangent Loss ◽  
Frequency Range ◽  
Scanning Calorimetry ◽  
Glass Transition Temperatures ◽  
Weight Losses ◽  
Quenching Method ◽  
Scanning Electron

Boroaluminosilicate glasses containing La2O3 were prepared by the normal quenching method. The glass transition temperatures (Tg) were measured by differential scanning calorimetry (DSC). The structural role of RO was investigated by nuclear magnetic resonance (NMR). Chemical durability was evaluated by weight losses of glass samples after immersion in HC1 solution. High resolution scanning electron microscopy (HR-SEM) was used to examine the surface micrographs of corroded glass samples. The dielectric constant and tangent loss were measured in the frequency range 10–106 Hz. The results revealed that chemical durability and dielectric properties increased with increasing La2O3 content.

scholarly journals Snow dielectric properties: from DC to microwave X-band

1994 ◽  
Vol 19 ◽  
pp. 92-96 ◽  
Author(s):  
TH. Achammer ◽  
A. Denoth
Keyword(s):  
Grain Size ◽  
Dielectric Properties ◽  
Water Content ◽  
Liquid Water ◽  
Liquid Water Content ◽  
Frequency Range ◽  
Snow Density ◽  
Cold Room ◽  
X Band ◽  
Grain Size And Shape

Broadband measurements of dielectric properties of natural snow samples near or at 0°C are reported. Measurement quantities are: dielectric permittivity, loss factor and complex propagation factor for electromagnetic waves. X-band measurements were made in a cold room in the laboratory; measurements at low and intermediate frequencies were carried out both in the field (Stubai Alps, 3300 m; Hafelekar near Innsbruck, 2100 m) and in the cold room. Results show that in the different frequency ranges the relative effect on snow dielectric properties of the parameters: density, grain-size and shape, liquid water content, shape and distribution of liquid inclusions and content of impurities, varies significantly. In the low-frequency range the influence of grain-size and shape and snow density dominates; in the medium-frequency range liquid water content and density are the dominant parameters. In the microwave X-band the influence of the amount, shape and distribution of liquid inclusions and snow density is more important than that of the remaining parameters.

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