Electric Field Tension Research Articles

Effect of electric field strength and droplet diameter on droplet–interface coalescence mechanism

Under high-strength electric fields, partial coalescence may occur, thus producing fine secondary droplets, which are undesirable for separating water from oil. In this study, experimental and numerical methods are employed to investigate the coalescence behavior under a DC electric field to comprehensively understand the effect of electric field strength (E) and droplet diameter (D) on coalescence. The Level-set method is employed to capture the moving interface, and the numerical data are validated through experimental tests. The results reveal the easy formation of secondary droplets with increasing E and D values. In particular, the electric field strength suppresses the expansion of the liquid bridge and hinders the vertical collapse of the droplets. The distortion of the electric field at the liquid bridge and the polarized charge both increase with E, thus resulting in stronger electric field repulsion. Moreover, the enhancement in D significantly affects the shrinkage of the liquid bridge and prevents the vertical collapse of the droplet. The pressure gradient at the liquid bridge from the outside to inside decreases as a function of D, thereby inhibiting the contraction speed. Furthermore, the number of polarized charges concentrated on the top of the droplet increases, thus resulting in an enhanced electric field tension. The results obtained herein can potentially act as guide for the design and optimization of electric dehydrators.

FDTD Simulations of Shell Scattering in Au@SiO2 Core-Shell Nanorods with SERS Activity for Sensory Purposes.

The article describes the results of Finite-Difference Time-Domain (FDTD) mathematical modeling of electromagnetic field parameters near the surfaces of core-shell gold-based nanorods in the Au@SiO2 system. Three excitation linewidths (λ = 532, 632.8, and 785 nm) were used for theoretical experiments. Electric field parameters for Au nanorods, Au@SiO2 nanorods, and hollow SiO2 shells have been calculated and evaluated. The correlations between electric field calculated parameters with nanorod morphology and shell size parameters have been clarified. The optical properties of nanoobjects have been simulated and discussed. The highest maximum calculated value of the electric field tension was E = 7.34 V/m. The enhancement coefficient was |E/E0|4 = 3.15 × 107 and was obtained on a rod with a SiO2 shell with dimensional parameters of height 70 nm, rod width 20 nm, and shell thickness 20 nm. As a result, a flexible simulation algorithm has been developed for the simulation of electric field parameters in each component of the Au@SiO2 system. The developed simulation algorithm will be applicable in the future for any other calculations of optical parameters in any similar component of the core-shell system.

Search for the optimal means for modelling the electric field of insulators

The article analyses software tools for simulation of electric field of insulators. The necessity of solving this problem is dictated by the fact that inaccuracy of simulation software allows stating that the simulation model cannot be improved correctly due to calculation errors in the program itself. Design features of different types of insulators, first of all, the most widespread and used - porcelain and glass insulators, are considered. The change of electric field in a glass and porcelain insulator operating in an AC network without contamination is described. Numerous calculation methods such as boundary element method, finite element method, integral equation method and others have been analysed. It is revealed, that from the point of view of functionality and expediency of application for solution of field problems relevant to electric power industry the finite difference method and finite element method are the most universal ones. The results of insulator electric field modelling using Ansoft Maxwell, CST EM Studio and Elcut software are given. Among Ansys, FEMLAB, Ansoft Maxwell, CST EM Studio, IES Coulomb and Elcut that were analyzed, the software Ansoft Maxwell and CST EM, where the finite element method is implemented, were chosen to solve the given problem. It was found out, which one of the software complies better with the given requirements as to accuracy (by calculation of error of deviation of mathematical modelling and experimental data) and in terms of the method incorporated in the algorithms of the software. Experimental data are compared with simulation results. The possibility of diagnosing insulators by electric field tension parameters has been revealed.

Study of the effect of cellulose fibers on the electrical strength of transformer oil

The electrical strength of transformer oil is the first parameter in transformer insulation tests. Such tests are carried out in a standard discharger according to the values of breakdown voltage. An abrupt decrease in electrical strength occurs when oil is contaminated with mechanical impurities. The greatest influence on the electric field is exerted by highly conductive cellulose fibers. The field between the electrodes may be severely distorted bya «bridge» of such fibers. At the same time, the influence of such particles is not taken into account in the tests. The problem is to experimentally determine the effect of such impurities on the breakdown strength. Thereby, this research poses and solves the problem of determining the dielectric strength of transformer oil in a standard discharger in the presence of cellulose fibers.To simulate electric field strengths, the ANSYS software package has been used. The basis of the 3D model was a standard measuring cell for determining breakdown voltage, which takes into account the boundary conditions in the form of a cube in which the electrode system is located, and the values of the electric field strength in the center of the electrode system.The electric field tension between the electrodes has been calculated, taking into account the influence of increased conductivity of cellulose fibers. It has been found that the electrical strength of oil gaps of moistened fibers with a length of more than 200 μm is significantly reduced, which is not taken into account when testing transformer oil for breakdown in a standard cell. This leads to inaccuracy in determining the electric strength of transformer oil in existing equipment.The results of the study can be used by operational services to improve the assessment of the quality of transformer oil used in power transformers as insulation. The results also can be used to study the mechanisms of electrophysical processes occurring in liquid dielectrics in the presence of fibers.

The method of conditional boundary

The goal of this work is to propose a new approach to the calculation of electromagnetic field that excited by the eddy current induced in the conductive environment the influence of an external magnetic field source. The quasistationary approximation accepted, that is, the bias currents do not take into account. Method. The main feature of the method is the introduction of so-called conditional boundary. This name is given for mental surfaces, which can be done in the area, free of conductive environment. Boundary form is arbitrary and dictated by considerations of calculations convenience. The agreement that the same boundary conditions, like on the conductor-vacuum boundary are performed. We prove that this task change leads to a change in its decisions only outside of the conductor and the only for part of the electric field. Magnetic induction vector throughout the space, as well as electric field tension vector in the conductive environment do not change. At the same time, a good choice of conditional boundary in some cases allows to simplify the task with calculation point of view. In addition to the conditional boundaries introduction, some formal basic conversion ratios are proposed, describing quasistationary electromagnetic field. These changes had the same goal to simplify calculations. The result. The new formulation of task of quasistationary electromagnetic field calculation is received in the form of differential equations system and boundary conditions, including both known ratio and the newly received. The new formulation is equivalent to traditional (with the above proviso). However, it has some advantages in terms of ease of calculation. The practical significance. In practice of specific calculations the method would be useful, particularly in cases when the form guide is close to some "simple" form.

Optical response of helix‐free FLC: Continuous gray scale, fastest response, and lowest control voltage

AbstractElectro‐optical response of a display cells with novel helix‐free FLC (differently, compensated helix ferroelectric—CHF) is considered. Predominance of the shear viscosity in the soliton mode of FLC director reorientation leads to weakening the temperature dependence of the response time. Increasing the electric field frequency expands this temperature interval, and it is 15°C… 45°C for the frequency about 3 kHz at ±1.5 V in a display cell with FLC viscosity of 0.7 P. Increasing the rotational viscosity up to 1.0 P provides the increase of speed ability due to Maxwell's nature of energy dissipation. The optical response time of 24 µs and light modulation frequency of 7 kHz were achieved at the amplitude of control voltage pulses ±1.5 V.Thus, like NLC based cells, the experimental samples of CHF based display cells at the same (or even lower) value of voltage and electric field tension (1–2 V/µm) show the continuous gray scale and hysteresis‐free modulation characteristic (up to 5 kHz) but can provide 40–50 times (!) higher speed. These break‐through results characterize CHF as the most high‐speed materials for future 3D displays and displays using field sequential color technique, including FLCoS and TFT addressed, as well as displays with new functional properties.

Hierarchic Model of Consciousness: From Molecular Bose Condensation to Synaptic Reorganization

Hierarchic Model of Consciousness, proposed in this work, is based on Hierarchic Theory of Matter and Field, developed by the author, its application to properties of water in microtubules (MT) and distant exchange electromagnetic interaction between MT. The evidence, based on our theory and Virial theorem, are considered, pointing to possibility of mesoscopic (intermediate between macroscopic and microscopic) molecular Bose condensation in any condensed matter. It is shown also, that conditions of nonlocality coincide with conditions of macroscopic Bose condensation, real in condensed matter and virtual in the Vacuum). In accordance to our Hierarchic Model of Consciousness (HMC), each specific kind of neuron ensembles excitation - corresponds to hierarchical system of three-dimensional (3D) standing waves of following interrelated kinds: thermal de Broglie waves (waves B), produced by anharmonic translations and librations of molecules; electromagnetic (IR) waves; acoustic waves (thermal phonons) and vibro-gravitational waves. Corresponding complex hologram may be responsible not only for quantum neurodynamics regulation, but for morphogenetic field also.In our model we consider corresponding quantum collective excitations, resulted from coherent anharmonic translational and librational oscillations of water molecules in the hollow core of the microtubules. This water fraction is most organized and orchestrated fraction of condensed matter in cells. The mechanism suggested, needs the existence the following hierarchical stages of each elementary act of perception and memory, as a consequence of simultaneous excitation and depolarization of big enough number of interacting quantum mechanically and classically neurons, forming cooperative ensemble: 1.The change of the electric field tension in the neuron's body, as a result of membranes depolarization, 2.Opening the potential dependent Ca2+ channels and increasing the concentration of these ions in cytoplasm. Activation of Ca2+ -dependent protein gelsolin, which stimulate fast disassembly of actin filaments.

INVESTIGATION OF SELF-ORGANIZATION PROCESSES IN SEMICONDUCTOR UNDER PHOTO-GUNN EFFECT

In the given paper, the results are presented of the investigation of non-equilibrium stationary carriers system in semiconductor under photo-Gunn effect. It was found that space-homogeneous state of the system is unstable in the case of negative differential conductivity and two waves of space-time perturbations with different phase velocities propagate through the crystal. Phase velocity degeneration conditions have been determined for these waves. Dependence of the complex attenuation decrement on external influences (electric field tension, incident light intensity, semiconductor compensation degree and spectral range) has been investigated in details. State dynamics of inhomogeneous carrier system has been studied using synergetics methods. Obtained results prove that one can controllably switch between the oscillation states of electron subsystem by changing the incident light intensity.