scholarly journals Electroconvective instability in a fluid layer

1970 ◽  
Vol 314 (1517) ◽  
pp. 269-283 ◽  
Keyword(s):  
Electrical Conductivity ◽  
Electric Field ◽  
Field Intensity ◽  
Electric Field Intensity ◽  
Hartmann Number ◽  
Fluid Layer ◽  
Uniform Electric Field ◽  
Steady Flows ◽  
Wide Range ◽  
Unstable Configuration

Steady flows of a fluid of slight electrical conductivity under the influence of an applied electric field intensity are often unstable. A study is described to illustrate with experiments and an analytical model the fundamental aspects of a wide range of instabilities that are characterized by the incipience of steady cellular convection as the electric Hartmann number H a e = ∈ E /√(μσ) is of the order of unity (∈ is the permittivity, E the imposed electric field intensity, μ the viscosity, and σ the electrical conductivity). A non-uniform electric field is used to induce an unstable configuration of surface charge and electric field intensity at a planar interface. The resulting instability leads to cellular convection in the plane of the interface. Predictions of the electric Hartmann number and wavelength for incipience of instability compare favourably to measurements. The dependence of the measured cellular convection velocity, resulting from the instability, on electric Hartmann number and electric Reynolds number are also in satisfactory agreement with the predictions from the simple model.

Electrostatic Dispensing of Dry Dielectric Materials

2001 ◽  
Vol 700 ◽  
Author(s):  
Malinda M. Tupper ◽  
Marjorie E. Chopinaud ◽  
Takamichi Ogawa ◽  
Michael J. Cima
Keyword(s):  
Electric Field ◽  
Field Intensity ◽  
Electric Field Intensity ◽  
Dielectric Materials ◽  
Nonuniform Electric Field ◽  
Sodium Fluorescein ◽  
Silica Spheres ◽  
Electrode Geometry ◽  
Wide Range ◽  
Silica Beads

AbstractDispensing micron-scale dielectric materials can be achieved through the use of dielectrophoresis. Electrodes are designed to create a nonuniform electric field. This method is expected to be applicable for transfer of a wide range of dielectric powders as well as small, shaped components. Small, 150 μm diameter silica spheres, as well as sodium fluorescein powder have been dispensed by this method. Selecting the appropriate electrode geometry and electric field intensity controls the amount collected. As little as 1.0 μg of sodium fluorescein powder, and as much as 16 mg of silica beads have been collected, and repeatability within 10 % of the total amount dispensed has been achieved.

scholarly journals Conductivity change with needle electrode during high frequency irreversible electroporation: a finite element study

2019 ◽  
Vol 25 (4) ◽  
pp. 237-242
Author(s):  
Amir Khorasani ◽  
Seyed Mohammad Firoozabadi ◽  
Zeinab Shankayi
Keyword(s):  
Electrical Conductivity ◽  
Electric Field ◽  
Field Intensity ◽  
High Frequency ◽  
Pulse Width ◽  
Electric Field Intensity ◽  
Electric Field Distribution ◽  
Irreversible Electroporation ◽  
Tissue Conductivity ◽  
Conductivity Change

Abstract Irreversible electroporation (IRE) is a process in which the cell membrane is damaged and leads to cell death. IRE has been used as a minimally invasive ablation tool. This process is affected by some factors. The most important factor is the electric field distribution inside the tissue. The electric field distribution depends on the electric pulse parameters and tissue properties, such as the electrical conductivity of tissue. The present study focuses on evaluating the tissue conductivity change due to high-frequency and low-voltage (HFLV) as well as low-frequency and high-voltage (LFHV) pulses during irreversible electroporation. We were used finite element analysis software, COMSOL Multiphysics 5.0, to calculate the conductivity change of the liver tissue. The HFLV pulses in this study involved 4000 bipolar and monopolar pulses with a frequency of 5 kHz, pulse width of 100 µs, and electric field intensity from 100 to 300 V/cm. On the other hand, the LFHV pulses, which we were used, included 8 bipolar and monopolar pulses with a frequency of 1 Hz, the pulse width of 2 ms and electric field intensity of 2500 V/cm. The results demonstrate that the conductivity change for LFHV pulses due to the greater electric field intensity was higher than for HFLV pulses. The most significant conclusion is the HFLV pulses can change tissue conductivity only in the vicinity of the tip of electrodes. While LFHV pulses change the electrical conductivity significantly in the tissue of between electrodes.

scholarly journals Toward Colloidal Motors

2017 ◽  
Vol 61 (1) ◽  
pp. 15
Author(s):  
Miklós Zrínyi ◽  
Masami Nakano
Keyword(s):  
Electric Field ◽  
Direct Observation ◽  
Field Intensity ◽  
Electric Motor ◽  
Rotational Speed ◽  
Electric Field Intensity ◽  
Wide Range ◽  
Dc Electric Field

We have presented the first direct observation of electric field induced rotation of epoxy based polymer rotors. Polymer disks and gears were prepared in few micrometer dimensions as rotors. Electrorotation of these sub-millimeter sized tools was studied under uniform DC electric field. The rotational speed of micron-sized polymer rotors can be conveniently tuned in wide range (between 300 – 3000 rpm) by the DC electric field intensity, opening new perspectives for their use in micro electric motor applications.

An Investigation of Behaviours of Bubble in Electric Field

2011 ◽  
Vol 347-353 ◽  
pp. 3184-3188
Author(s):  
Zhi Guang Dong ◽  
Zhi Hui Dong
Keyword(s):  
Aspect Ratio ◽  
Electric Field ◽  
Field Intensity ◽  
Bubble Growth ◽  
Electric Field Intensity ◽  
Uniform Electric Field ◽  
Electric Stress

The effects of an ununiform electric field on bubble behaviours such as bubble growth ,deformation and detachment are investigated experimentally.Experimental results show that the bubble elongated along the direction of the electric field.The bubble’s aspect ratio is increased with the increasing of electric field intensity and the ellipse sphere shape is more evident than without electric field,while its departure volume is decreased with that.The case is the bubble comes under the electric stress.The electric stress compressed the bubble in the equatorial direction and extened the bubble along the axial direction.The bubble behaviours influenced in the ununiform electric field is more evident than the uniform electric field.

scholarly journals A numerical study on the effect of conductivity change in cell kill distribution in irreversible electroporation

2020 ◽  
Vol 26 (2) ◽  
pp. 69-76
Author(s):  
Amir Khorasani
Keyword(s):  
Electrical Conductivity ◽  
Electric Field ◽  
Electric Conductivity ◽  
Field Intensity ◽  
Electric Field Intensity ◽  
Irreversible Electroporation ◽  
Conductivity Change ◽  
Death Probability ◽  
Cell Kill ◽  
The Impact

AbstractIntroduction: irreversible electroporation (IRE) is a tissue ablation technique and physical process used to kill the undesirable cells. In the IRE process by mathematical modelling we can calculate the cell kill probability and distribution inside the tissue. The purpose of the study is to determine the influence of electric conductivity change in the IRE process into the cell kill probability and distribution.Methods: cell death probability and electric conductivity were calculated with COMSOL Multiphysics software package. 8 pulses with a frequency of 1 Hz, pulse width of 100 µs and electric field intensity from 1000 to 3000 V/Cm with steps of 500 V/Cm used as electric pulses.Results: significantly, the electrical conductivity of tissue will increase during the time of pulse delivery. According to our results, electrical conductivity increased with an electric field intensity of pulses. By considering the effect of conductivity change on cell kill probability, the cell kill probability and distribution will change.Conclusion: we believe that considering the impact of electric conductivity change on the cell kill probability will improve the accuracy of treatment outcome in the clinic for treatment with IRE.

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.

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