scholarly journals Radio frequency heating for corn seeds: Model development and uniformity optimization

2020 ◽  
Vol 189 ◽  
pp. 01016
Author(s):  
Shuo Wei ◽  
Fenghe Wang ◽  
Ben Fan ◽  
Deyong Yang
Keyword(s):  
Electric Field ◽  
Radio Frequency ◽  
Field Intensity ◽  
Electric Field Intensity ◽  
Model Development ◽  
Rf Heating ◽  
Radio Frequency Heating ◽  
Treatment Protocols ◽  
Sample Shape ◽  
Heating Uniformity

Radio frequency (RF) heating has been considered as a promising method for food pasteurization and disinfestations, materials and heating uniformity are the main considerations in developing and scaling-up RF treatment protocols. In this study, an experimentally validated model of corn seeds was developed to investigate its RF heating characteristics and effects of sample shape on heating uniformity. Results showed that hot spots distributed in the corners and edges but cold ones in the centre of the rectangular sample, which led to the concentration of electric field at the sample edges, thus increased their electric field intensity and loss power. Comparing the temperature distributions of corn samples in six shapes, the best heating uniformity was observed in the special round sample (round corners, edges and surfaces), its uniformity index was 0.04, as its special round surface made the direction of the electromagnetic field in the sample incline to the centre, and homogenized the electric field intensity and loss power density. The results provide an evidence for temperature prediction and uniformity improvement of corn seeds during RF heating.

scholarly journals Evaluation of heating uniformity in radio frequency heating systems using carrot and radish

2016 ◽  
Vol 30 (4) ◽  
pp. 465-473 ◽  
Author(s):  
Ling Kong ◽  
Min Zhang ◽  
Yuchuan Wang ◽  
Benu Adhikari ◽  
Zaixing Yang
Keyword(s):  
Temperature Distribution ◽  
Radio Frequency ◽  
Temperature Rise ◽  
Industrial Applications ◽  
Food Samples ◽  
Central Position ◽  
Rf Heating ◽  
Radio Frequency Heating ◽  
Heating Uniformity ◽  
Frequency Heating

Abstract Lack of heating uniformity is a major problem impeding the broader adaptation of radio frequency heaters in industrial applications. The overall aim of this study was to evaluate the uniformity of heating or temperature distribution within food samples (three different carrot and one radish rectangles) placed vertically and horizontally within a radio frequency heating cavity. The intensity of the electric field in radio frequency was found to be symmetrical. The temperatures at the vertically top positions were lower than the vertically bottom positions at the equidistance from the vertical center with the highest was at the vertically central position. The rate of temperature rise at all the positions were higher in taller (higher mass) than the shorter (lower mass) rectangles of carrots. The temperatures at the corners and edges were lower than at the cross sectionally central positions at all the heights tested in both carrots and radishes. The rate of temperature rise at all the vertical positions was higher in radish rectangles than in the carrot rectangles of the same dimensions. The similarity of temperature distribution in carrot and radish rectangles suggested that the heating patterns and uniformity in carrots and radishes in RF heating were almost the same.

High-speed isotachophoresis. Analytical aspects of the steady-state longitudinal temperature profiles

1979 ◽  
Vol 44 (3) ◽  
pp. 841-853 ◽  
Author(s):  
Zbyněk Ryšlavý ◽  
Petr Boček ◽  
Miroslav Deml ◽  
Jaroslav Janák
Keyword(s):  
Steady State ◽  
Temperature Distribution ◽  
Electric Field ◽  
Field Intensity ◽  
Electric Field Intensity ◽  
Minor Component ◽  
Physical Models ◽  
Temperature Profiles ◽  
Longitudinal Temperature ◽  
Continuous Character

The problem of the longitudinal temperature distribution was solved and the bearing of the temperature profiles on the qualitative characteristics of the zones and on the interpretation of the record of the separation obtained from a universal detector was considered. Two approximative physical models were applied to the solution: in the first model, the temperature dependences of the mobilities are taken into account, the continuous character of the electric field intensity at the boundary being neglected; in the other model, the continuous character of the electric field intensity is allowed for. From a comparison of the two models it follows that in practice, the variations of the mobilities with the temperature are the principal factor affecting the shape of the temperature profiles, the assumption of a discontinuous jump of the electric field intensity at the boundary being a good approximation to the reality. It was deduced theoretically and verified experimentally that the longitudinal profiles can appreciably affect the longitudinal variation of the effective mobilities in the zone, with an infavourable influence upon the qualitative interpretation of the record. Pronounced effects can appear during the analyses of the minor components, where in the corresponding short zone a temperature distribution occurs due to the influence of the temperatures of the neighbouring zones such that the temperature in the zone of interest in fact does not attain a constant value in axial direction. The minor component does not possess the steady-state mobility throughout the zone, which makes the identification of the zone rather difficult.

POLARON IN A QUANTUM DOT UNDER AN ELECTRIC FIELD

2007 ◽  
Vol 21 (24) ◽  
pp. 1635-1642
Author(s):  
MIAN LIU ◽  
WENDONG MA ◽  
ZIJUN LI
Keyword(s):  
Quantum Dot ◽  
Electric Field ◽  
Field Intensity ◽  
Ground State Energy ◽  
Ground State ◽  
Electric Field Intensity ◽  
State Energy ◽  
Theoretical Study ◽  
The Moment ◽  
Transformation Methods

We conducted a theoretical study on the properties of a polaron with electron-LO phonon strong-coupling in a cylindrical quantum dot under an electric field using linear combination operator and unitary transformation methods. The changing relations between the ground state energy of the polaron in the quantum dot and the electric field intensity, restricted intensity, and cylindrical height were derived. The numerical results show that the polar of the quantum dot is enlarged with increasing restricted intensity and decreasing cylindrical height, and with cylindrical height at 0 ~ 5 nm , the polar of the quantum dot is strongest. The ground state energy decreases with increasing electric field intensity, and at the moment of just adding electric field, quantum polarization is strongest.

scholarly journals Effects of Flash Sintering Parameters on Performance of Ceramic Insulator

Energies ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 1157
Author(s):  
Yong Liu ◽  
Xingwang Huang
Keyword(s):  
Grain Size ◽  
Electric Field ◽  
Field Intensity ◽  
Current Density ◽  
Electric Field Intensity ◽  
Unit Cell ◽  
Uniform Structure ◽  
Ceramic Insulator ◽  
Flash Sintering ◽  
Ceramic Insulators

Ceramic outdoor insulators play an important role in electrical insulation and mechanical support because of good chemical and thermal stability, which have been widely used in power systems. However, the brittleness and surface discharge of ceramic material greatly limit the application of ceramic insulators. From the perspective of sintering technology, flash sintering technology is used to improve the performance of ceramic insulators. In this paper, the simulation model of producing the ceramic insulator by the flash sintering technology was set up. Material Studio was used to study the influence of electric field intensity and temperature on the alumina unit cell. COMSOL was used to study the influence of electric field intensity and current density on sintering speed, density and grain size. Obtained results showed that under high temperature and high voltage, the volume of the unit cell becomes smaller and the atoms are arranged more closely. The increase of current density can result in higher ceramic density and larger grain size. With the electric field intensity increasing, incubation time shows a decreasing tendency and energy consumption is reduced. Ceramic insulators with a higher uniform structure and a smaller grain size can show better dielectric performance and higher flashover voltage.

scholarly journals Frequency-Tunable Terahertz Plasmonic Structure Based on the Solid Immersed Method for Sensing

Sensors ◽  
2021 ◽  
Vol 21 (4) ◽  
pp. 1419
Author(s):  
Toshio Sugaya ◽  
Yukio Kawano
Keyword(s):  
Electric Field ◽  
Field Intensity ◽  
Electric Field Intensity ◽  
Wavelength Region ◽  
Diffraction Limit ◽  
Field Analysis ◽  
Plasmonic Structure ◽  
Sensing Applications ◽  
Frequency Tunable ◽  
Bull's Eye

Terahertz waves are located in the frequency band between radio waves and light, and they are being considered for various applications as a light source. Generally, the use of light requires focusing; however, when a terahertz wave is irradiated onto a small detector or a small measurement sample, its wavelength, which is much longer than that of visible light, causes problems. The diffraction limit may make it impossible to focus the terahertz light down to the desired range by using common lenses. The Bull’s Eye structure, which is a plasmonic structure, is a promising tool for focusing the terahertz light beyond the diffraction limit and into the sub-wavelength region. By utilizing the surface plasmon propagation, the electric field intensity and transmission coefficient can be enhanced. In this study, we improved the electric field intensity and light focusing in a small region by adapting the solid immersion method (SIM) from our previous study, which had a frequency-tunable nonconcentric Bull’s Eye structure. Through electromagnetic field analysis, the electric field intensity was confirmed to be approximately 20 times higher than that of the case without the SIM, and the transmission measurements confirmed that the transmission through an aperture had a gap of 1/20 that of the wavelength. This fabricated device can be used in imaging and sensing applications because of the close contact between the transmission aperture and the measurement sample.

scholarly journals Frequency-Dependent FDTD Algorithm Using Newmark’s Method

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Bing Wei ◽  
Le Cao ◽  
Fei Wang ◽  
Qian Yang
Keyword(s):  
Differential Equation ◽  
Electric Field ◽  
Field Intensity ◽  
Time Domain ◽  
Difference Method ◽  
Electric Field Intensity ◽  
Polarization Vector ◽  
Solution Stability ◽  
Central Difference ◽  
Central Difference Method

According to the characteristics of the polarizability in frequency domain of three common models of dispersive media, the relation between the polarization vector and electric field intensity is converted into a time domain differential equation of second order with the polarization vector by using the conversion from frequency to time domain. Newmarkβγdifference method is employed to solve this equation. The electric field intensity to polarizability recursion is derived, and the electric flux to electric field intensity recursion is obtained by constitutive relation. Then FDTD iterative computation in time domain of electric and magnetic field components in dispersive medium is completed. By analyzing the solution stability of the above differential equation using central difference method, it is proved that this method has more advantages in the selection of time step. Theoretical analyses and numerical results demonstrate that this method is a general algorithm and it has advantages of higher accuracy and stability over the algorithms based on central difference method.

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