scholarly journals What Determines the Parameters of a Propagating Streamer: A Comparison of Outputs of the Streamer Parameter Model and of Hydrodynamic Simulations

Atmosphere ◽  
2021 ◽  
Vol 12 (12) ◽  
pp. 1664
Author(s):  
Nikolai G. Lehtinen ◽  
Robert Marskar
Keyword(s):  
Experimental Data ◽  
Electric Field ◽  
Electric Discharge ◽  
Propagation Velocity ◽  
The Novel ◽  
Hydrodynamic Simulation ◽  
Hydrodynamic Simulations ◽  
Important Stage ◽  
Streamer Discharges

Electric streamer discharges (streamers) in the air are a very important stage of lightning, taking place before formation of the leader discharge, and with which an electric discharge starts from conducting objects which enhance the background electric field, such as airplanes. Despite years of research, it is still not well understood what mechanism determines the values of a streamer’s parameters, such as its radius and propagation velocity. The novel Streamer Parameter Model (SPM) was made to explain this mechanism, and to provide a way to efficiently calculate streamer parameters. Previously, we demonstrated that SPM results compared well with a limited set of experimental data. In this article, we compare SPM predictions to the published hydrodynamic simulation (HDS) results.

scholarly journals What Determines the Parameters of a Propagating Streamer: A Comparison of Outputs of the Streamer Parameter Model and of Hydrodynamic Simulations

2021 ◽  
Author(s):  
Nikolai G. Lehtinen ◽  
Robert Marskar
Keyword(s):  
Experimental Data ◽  
Electric Discharge ◽  
Propagation Velocity ◽  
Hydrodynamic Simulation ◽  
Hydrodynamic Simulations ◽  
Important Stage ◽  
Streamer Discharges

Electric streamer discharges (streamers) in air are a very important stage of lightning, taking place before formation of the leader discharge, and with which an electric discharge starts from conducting objects which enhance the background elecric field, such as airplanes. Despite years of research, it is still not well understood what mechanism determines the values of streamer parameters, such as its radius and propagation velocity. The Streamer Parameter Model (SPM) is aimed to understand this mechanism, as well as to provide a way to efficiently calculate streamer parameters. Previously, we demonstrated that SPM results compared well with a limited set of experimental data. In this Brief Report, we compare SPM predictions to the published hydrodynamic simulation (HDS) results.

Hydrodynamic Simulation of Drift Mobility in N-Hg0.8Cd0.2Te

2011 ◽  
Vol 312-315 ◽  
pp. 122-126
Author(s):  
Mebarka Daoudi ◽  
Abderrahmane Belghachi ◽  
Luca Varani ◽  
Christophe Palermo
Keyword(s):  
Experimental Data ◽  
Electric Field ◽  
Dominant Role ◽  
Impurity Scattering ◽  
Drift Mobility ◽  
Scattering Mechanism ◽  
Hydrodynamic Simulation ◽  
Monte Carlo Calculations ◽  
Ionized Impurity Scattering ◽  
Good Agreement

In this paper, the transport properties of Hg0.8Cd0.2Te have been investigated at 77 K using the hydrodynamic model. We remarked that ionized impurity scattering mechanism plays a dominant role in this material at low electric field. The drift velocity, mean energy and drift mobility are determined as functions of the electric field strength. Comparison is made with Monte Carlo calculations and experimental results. The obtained velocity-field curve is in good agreement with reported experimental data.

Calculation and Measurement of the Stiffness and Damping Coefficients for a Low Impedance Hydrodynamic Bearing

1997 ◽  
Vol 119 (1) ◽  
pp. 57-63 ◽  
Author(s):  
M. J. Goodwin ◽  
P. J. Ogrodnik ◽  
M. P. Roach ◽  
Y. Fang
Keyword(s):  
Experimental Data ◽  
Dynamic Stiffness ◽  
Perturbation Technique ◽  
The Novel ◽  
Oil Film ◽  
Hydrodynamic Bearing ◽  
Damping Coefficients ◽  
Stiffness And Damping ◽  
Film Stiffness ◽  
Novel Design

This paper describes a combined theoretical and experimental investigation of the eight oil film stiffness and damping coefficients for a novel low impedance hydrodynamic bearing. The novel design incorporates a recess in the bearing surface which is connected to a standard commercial gas bag accumulator; this arrangement reduces the oil film dynamic stiffness and leads to improved machine response and stability. A finite difference method was used to solve Reynolds equation and yield the pressure distribution in the bearing oil film. Integration of the pressure profile then enabled the fluid film forces to be evaluated. A perturbation technique was used to determine the dynamic pressure components, and hence to determine the eight oil film stiffness and damping coefficients. Experimental data was obtained from a laboratory test rig in which a test bearing, floating on a rotating shaft, was excited by a multi-frequency force signal. Measurements of the resulting relative movement between bearing and journal enabled the oil film coefficients to be measured. The results of the work show good agreement between theoretical and experimental data, and indicate that the oil film impedance of the novel design is considerably lower than that of a conventional bearing.

TEMPERATURE-DEPENDENCE OF PROTON CONDUCTIVITY IN HYDROGEN-BONDED MOLECULAR SYSTEMS

2007 ◽  
Vol 21 (19) ◽  
pp. 1239-1252 ◽  
Author(s):  
XIAO-FENG PANG ◽  
BO DENG ◽  
HUAI-WU ZHANG ◽  
YUAN-PING FENG
Keyword(s):  
Experimental Data ◽  
Electric Field ◽  
Temperature Dependence ◽  
Electric Conductivity ◽  
Proton Conductivity ◽  
Model System ◽  
Time Dependent ◽  
Molecular Systems ◽  
Damping Effect ◽  
Hydrogen Bonded

The temperature-dependence of proton electric conductivity in hydrogen-bonded molecular systems with damping effect was studied. The time-dependent velocity of proton and its mobility are determined from the Hamiltonian of a model system. The calculated mobility of (3.57–3.76) × 10-6 m 2/ Vs for uniform ice is in agreement with the experimental value of (1 - 10) × 10-2 m 2/ Vs . When the temperature and damping effects of the medium are considered, the mobility is found to depend on the temperature for various electric field values in the system, i.e. the mobility increases initially and reaches a maximum at about 191 K, but decreases subsequently to a minimum at approximately 241 K, and increases again in the range of 150–270 K. This behavior agrees with experimental data of ice.

Effect of an electric field on the normal propagation velocity of a flame

1976 ◽  
Vol 12 (3) ◽  
pp. 362-366 ◽  
Author(s):  
B. G. D'yachkov ◽  
I. Ya. Polonskii ◽  
A. S. Klimov
Keyword(s):  
Electric Field ◽  
Propagation Velocity ◽  
Normal Propagation

BALLISTIC ELECTRON ACCELERATION NEGATIVE-DIFFERENTIAL-CONDUCTIVITY DEVICES

2007 ◽  
Vol 17 (01) ◽  
pp. 173-176 ◽  
Author(s):  
BARBAROS ASLAN ◽  
LESTER F. EASTMAN ◽  
WILLIAM J. SCHAFF ◽  
XIAODONG CHEN ◽  
MICHAEL G. SPENCER ◽  
...  
Keyword(s):  
Experimental Data ◽  
Electric Field ◽  
Electron Acceleration ◽  
Negative Differential Conductivity ◽  
Differential Conductivity ◽  
Experimental Development ◽  
Ballistic Electron

We present the experimental development and characterization of GaN ballistic diodes for THz operation. Fabricated devices have been described and gathered experimental data is discussed. The major problem addressed is the domination of the parasitic resistances which significantly reduce the accelerating electric field across the ballistic region (intrinsic layer).

scholarly journals Study of the influence of initial-state fluctuations on hydrodynamic simulations

2020 ◽  
Vol 245 ◽  
pp. 06005
Author(s):  
Marcin Słodkowski ◽  
Patryk Gawryszewski ◽  
Dominik Setniewski
Keyword(s):  
Initial Conditions ◽  
Graphics Processing Unit ◽  
Heavy Ion ◽  
Processing Unit ◽  
Initial State ◽  
Final State ◽  
Hydrodynamic Simulation ◽  
Hydrodynamic Simulations ◽  
Cartesian Coordinate ◽  
Ion Collision

In this work, we are focusing on assessing the contribution of the initial-state fluctuations of heavy ion collision in the hydrodynamic simulations. We are trying to answer the question of whether the hydrodynamic simulation retains the same level of fluctuation in the final-state as for the initial stage. In another scenario, the hydrodynamic simulations of the fluctuation drowns in the final distribution of expanding matter. For this purpose, we prepared sufficient relativistic hydrodynamic program to study A+A interaction which allows analysing initial-state fluctuations in the bulk nuclear matter. For such an assumption, it is better to use high spatial resolution. Therefore, we applied the (3+1) dimensional Cartesian coordinate system. We implemented our program using parallel computing on graphics cards processors - Graphics Processing Unit (GPU). Simulations were carried out with various levels of fluctuation in initial conditions using the average method of events coming from UrQMD models. Energy density distributions were analysed and the contribution of fluctuations in initial conditions was assessed in the hydrodynamic simulation.

scholarly journals Моделирование плазмы короткодугового ксенонового разряда сверхвысокого давления

2019 ◽  
Vol 89 (10) ◽  
pp. 1556
Author(s):  
Н.А. Тимофеев ◽  
В.С. Сухомлинов ◽  
G. Zissis ◽  
И.Ю. Мухараева ◽  
Д.В. Михайлов ◽  
...  
Keyword(s):  
Experimental Data ◽  
Field Strength ◽  
Electric Field ◽  
Electric Field Strength ◽  
Arc Discharge ◽  
Plasma Temperature ◽  
Cathode Region ◽  
Ultrahigh Pressure ◽  
Thoriated Tungsten ◽  
Ionization Balance

AbstractWe have studied a high- (ultrahigh-) pressure short-arc discharge in xenon with thoriated tungsten cathodes. A system of equations formulated based on earlier experimental data indicating possible emission of cathode material (thorium) into the discharge gap has made it possible to determine the electric field strength, plasma temperature, and concentration of thorium atoms as well as thorium and xenon ions in the plasma. The problem has been solved for a model discharge between planar electrodes. The results indicate the key role of thorium atoms in the cathode region. Thorium atoms determine the ionization balance and other electrokinetic properties of plasma. Emission of thorium atoms reduces the plasma temperature at the cathode, which turns out to be noticeably lower than the plasma temperature near the anode; this is a new result that agrees with experimental data. Other electrokinetic characteristics of the plasma (in particular, charged particle concentration and electric field strength) are also in good agreement with the experiment.

scholarly journals Anisotropic Diffusion and the Townsend?Huxley Experiment

1973 ◽  
Vol 26 (4) ◽  
pp. 469 ◽  
Author(s):  
JJ Lowke
Keyword(s):  
Experimental Data ◽  
Electric Field ◽  
Electron Mobility ◽  
Diffusion Coefficients ◽  
Applied Electric Field ◽  
Anisotropic Diffusion ◽  
Diffusion Tubes ◽  
New Formula ◽  
The Relationship ◽  
Diffusion Tube

The relationship between current ratios and electron diffusion coefficients for the Townsend-Huxley experiment is reanalysed with the assumption that diffusion can be represented by two coefficients DT and DL for diffusion transverse and parallel respectively to the applied electric field. When the new formula is used to interpret previous experimental data obtained with a diffusion tube of length 2 cm, the derived values of DT/fl become independent of pressure (fl being the electron mobility). For longer diffusion tubes (~ 6 cm), current ratios are insensitive to DL and the results differ insignificantly from those obtained using the formula previously derived on the assumption that diffusion is isotropic.

Approaches for the synthesis, chemical modification and biological properties of N-acylphenothiazines

2021 ◽  
Vol 10 (4) ◽  
pp. 377-392 ◽  
Author(s):  
Iryna Myrko ◽  
Taras Chaban ◽  
Yulia Matiichuk ◽  
Mohammad Arshad ◽  
Vasyl Matiychuk
Keyword(s):  
Experimental Data ◽  
Chemical Modification ◽  
Medicinal Chemistry ◽  
Biological Properties ◽  
Chemotherapeutic Agents ◽  
Present Review ◽  
The Novel ◽  
Pharmacological Activities ◽  
The Past ◽  
Biological Potential

In this review we systematized the theoretical and experimental data concerning the versatile approaches for the synthesis of N-acylphenothiazines. The aim of the study was to compile the literature reported worldwide in the past 20 years. This article also reviewed the analysis of pharmacological activities of these heterocycles as one of the promising chemotherapeutic objects for the modern bioorganic and medicinal chemistry. It has been hypothesized that the enormous biological potential of these moieties is due to the radical nature in the acyl moiety. Therefore, the present review will be a good contribution to the literature and will provide the platform for the medicinal chemistry researchers to carry out more studies aiming the N-acylphenothiazine moieties as the novel chemotherapeutic agents.

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