Electric Field Strength Research Articles

Разработка и исследование имитационной модели мультикамерного разрядника для грозозащитного троса

Optical fiber overhead ground wire (OPGW) is an effective solution for laying mainline digital communications along high-voltage power lines. It allows you to use the existing infrastructure of the power grid and ensure the transfer of a large amount of data. The flow of lightning currents and short-circuit currents can cause a violation of the thermal resistance of the fiber and a deterioration of its performance. When the OPGW is insulated through an insulator shunted by a spark gap, during operation it is possible to change the distance in the discharge gap due to the displacement of the electrodes in the plane. Also, when the short circuit location is close, multiple overlaps will occur and as a result, short circuit current will flow through the OPGW. Thus, the article considers the possibility to use a device with a multielectrode system developed on the principle of a multichamber spark gap as a replacement of the spark gap to increase the reliability of the unit with an isolated OPGW suspension. Modeling of the device has been carried out in the ANSYS Maxwell software package, the mathematical apparatus of which is based on the use of Maxwell's differential equations and the finite element method, which allows performing numerical modeling with sufficiently high accuracy. A simulation model of a multichamber spark gap has been developed in the ANSYS Maxwell software package and calculations of electrical characteristics have been performed. For the electrode system of a multi-chamber arrester, an uneven distribution of the applied voltage across the spark discharge gaps of the chambers is determined. It is shown that when a voltage is applied to a spark gap, the highest electric field strength occurs between the first and second electrodes, and then a cascade of discharge gaps occurs, which provides the required low discharge voltages of the spark gap as a whole. The developed simplified simulation model of a multi-chamber arrester has shown all the necessary conditions for cascade imaging of the voltage distribution and the electric-field strength of various electrode options. Based on the research conducted electrodes geometry is identified for smart prototype development and ongoing multi-chamber arrester research.

Safety Assessment of Electromagnetic Environmental Exposure for GPS Antenna of Electric Vehicle

The present GPS (global positioning system) is widely used in electric vehicle navigation; it is usually installed in the middle-to-rear position on the car’s roof, near the rear windshield. Since the GPS antenna operating frequency is 1.575 GHz, the health risk of the passengers in the car in this high-frequency electromagnetic exposure is a matter of concern. In this paper, we construct models for a GPS antenna, an electric vehicle, and a human body. Through the multiphysics field coupling calculation in COMSOL Multiphysics, a finite element simulation software, in both frequency domain and transient analysis, we obtain the electric field strength distribution, specific absorption rate, and temperature distribution of the human body at three positions inside the electric vehicle after being exposed to the GPS antenna radiation for 30 minutes. The peak human-induced electric field is 18.4 V/m, and the peak specific absorption rate is 0.193 W/kg. The 30 minute average maximum human-induced electric field is 1.6906 V/m, which is 3.1% of the ICNIRP limit, the 30 minute average whole-body SAR is 0.0036 W/kg, which is 4.5% of the ICNIRP limit, and the 30 minute average human core temperature rise is 0.06°C, which is 6% of the ICNIRP limit. In addition, we simulate the impact of three different vehicle shell materials on the level of electromagnetic exposure to the human body, which can provide reference for electromagnetic shielding design in automobiles. The results indicate that the induced electric field strength, specific absorption rate (SAR), and temperature rise in various parts of the human body did not exceed the standard limits in the latest version of ICNIRP. This suggests that the electromagnetic exposure from the GPS antenna in a typical automotive environment does not pose a threat to human health.

Modeling the performance and bandwidth of single-atom adiabatic quantum memories

Quantum memories are essential for quantum repeaters, which will form the backbone of the future quantum internet. Such memory can capture a signal state for a controllable amount of time, after which this state can be retrieved. In this work, we theoretically investigated how atomic material and engineering parameters affect the performance and bandwidth of a quantum memory. We have applied a theoretical model for quantum memory operation based on the Lindblad master equation and adiabatic quantum state manipulation. The materials’ properties and their uncertainty are evaluated to determine the performance of Raman-type quantum memories by showcasing two defects in two-dimensional hexagonal boron nitride. We have derived a scheme to calculate the signal bandwidth based on the material parameters as well as the maximum efficiency that can be realized. The bandwidth depends on four factors: the signal photon frequency, the dipole transition moments in the electronic structure, the cavity volume, and the strength of the external control electric field. As our scheme is general and independent of materials, it can be applied to many other quantum materials with a suitable three-level structure. We, therefore, provided a promising route for designing and selecting materials for quantum memories. Our work is, therefore, an important step toward the realization of a large-scale quantum network.

Electro-optic characteristics of chiral nematic layers deformed by in-plane electric field

ABSTRACT Deformations of twisted and super-twisted layers composed of chiral and nonchiral nematic liquid crystals induced by in-plane electric field were studied numerically. The right-hand twisted structures with twist angles equal to 90°, 120°, 150°, 180°, 210°, 240° and 270° placed between crossed polarisers were considered. The optical transmission due to electro-optic effect which occurred in such systems was studied as a function of applied electric field strength. Steep and linear electro-optic characteristics were found in the case of nonchiral nematic confined in cells twisted by 90°. Such characteristics were favoured by large twist elastic constant, large dielectric anisotropy and weak azimuthal anchoring. In the case of super-twisted layers, useful characteristics were found for twist angles 210°, 240° and 270°, small twist elastic constant, strong azimuthal anchoring and large dielectric anisotropy.

Study on the Terahertz Spectroscopy Properties of Graphene Quantum Dots Based on Microfluidic Chip

Graphene quantum dots are quasi-zero-dimensional nanomaterials with unique physical and chemical properties. This study utilized a terahertz (THz) time-domain spectroscopy system to analyze the absorption characteristics of THz-waves by graphene quantum dots at different concentrations. Additionally, we applied electric fields and magnetic field to explore the THz-wave absorption properties of graphene quantum dots in greater detail. The results indicate that the THz absorbance of graphene quantum dots is positively correlated with sample concentration and applied electric field strength. However, it is negatively correlated with the intensity of the applied magnetic field. This work combines THz technology and microfluidic devices to propose a viable methodology for conducting in-depth study on graphene quantum dots.

A RT-FDTD method of analyzing wireless propagation characteristics in underground mine

Efficient communication is crucial in reducing injuries and fatalities in coal mine accidents, necessitating the study of simulation methods for mine communication. When transceiver antennas are positioned close to the same side of the tunnel, the simulation results from the Ray Tracing (RT) method exhibit significant errors. Additionally, the Finite-Difference Time-Domain (FDTD) method demands substantial computational resources. In response to these challenges, we propose a RT-FDTD method, guided by the law of conservation of energy. This approach involves dividing the mine tunnel into a cuboidal region, using the RT method to calculate the electric field strength on the cuboid’s surface, and then employing this as the excitation source for the FDTD method. Subsequently, the FDTD method is used to calculate the electric field strength within the cuboid. Experimental results demonstrate that the RT-FDTD method effectively mitigates the limitations of the RT and FDTD methods, enhancing both the efficiency and accuracy of simulations in underground mine.

Analytical determination of a quasi-stationary electromagnetic field created by magnetic moments and eddy currents in conducting half-space

Aim. Study of the distribution of a three-dimensional alternating quasi-stationary electromagnetic field at the surface of conducting half-space with strong skin-effect, the source of which is an arbitrarily oriented magnetic moment. Methodology. The expressions for non-uniform electromagnetic field with strong skin effect are used for the analysis, which is based on the found exact analytical solution of the general three-dimensional problem and the use of expansion into asymptotic series with respect to a small parameter that is proportional to the ratio of the field penetration depth to the distance between the sources of the external field and the surface of body. Specific expressions at the surface are completely determined by the known field of external sources. In this work, the external magnetic moment field is used. Results. For strong skin effect, expressions for the electric and magnetic field strength are obtained separately for the components of the magnetic moment oriented perpendicularly and parallel to the flat surface between the dielectric and conducting areas. The features of the electromagnetic field distribution are analyzed depending on the value of introduced small parameter. The results are presented for the module and phase shift of the field strength with respect to the phase of the external field source. Originality. The expressions found for the electromagnetic field appear to be more general than the use of closed contours with alternating current, since they extend types of external field sources and allow the use of the superposition method instead of integration over the entire contour. Practical value. The found specific analytical expressions of the electromagnetic field at the surface for the external field of magnetic moments significantly simplify the solution of the problems, since they do not require additional solution of the field equations. References 20, figures 8.

Coupling Process between Droplet and Iron Investigated by Reactive Molecular Dynamics Simulations.

The droplet-to-iron electrochemical reaction is common in nature and industrial production, and it causes damage to the economy, safety, and the environment. The electrochemical reaction of droplet-to-iron is a coupling process of wetting and corrosion. Presently, investigations into electrochemical reactions mainly focus on the corrosions caused by a solution, and wetting is rarely considered. However, for the droplet-to-iron electrochemical reaction, the mechanism of charge transfer in the process is still unclear. In this paper, a reactive molecular dynamics simulation model for the droplet-to-iron electrochemical reaction is developed for the first time. The electrochemical reaction of droplet-to-iron is studied, and the interaction between droplet wetting and corrosion on iron is investigated. The effects of temperature, electric field strength, and salt concentration on the electrochemical reaction are explored. Results show that droplet wetting on the iron surface and the formation of a single-molecular-layer ordered structure are prerequisites for corrosion. The hydroxyl radicals that penetrate the ordered structure acquire electrons from iron atoms on the substrate surface under the action of Coulomb forces and form iron-containing oxides with these iron atoms. The corrosion products and craters lead to a reduced droplet height, which promotes droplet wetting on iron and further intensifies the droplet-to-iron electrochemical reaction.

Unveiling the formic acid dehydrogenation dynamics steered by Strength-Controllable internal electric field from barium titanate

Formic acid is a desirable liquid hydrogen storage compound for solving transport and storage problems of hydrogen for onboard fuel cells. Optimizing adsorption/desorption energy of intermediates can directly modulate the performance of Pd catalysts in formic acid dehydrogenation (FAD). Herein, we introduce internal electric field with controllable strength to regulate the adsorption/desorption of intermediates on Pd. Non-ferroelectric cubic-phase barium titanate (CBT) is heat-treated at high temperature to obtain ferroelectric tetragonal-phase barium titanate (TBT(C)), which exhibits internal electric field. The strength of the internal electric field is successfully adjusted by heat treatment at different temperatures. The size of Pd nanoparticles is restricted between 2.2 and 2.7 nm, and the electronic effect of Pd is effectively eliminated by coating TBT(C) with mesoporous carbon shell (TBT(C)@SC). Experimental results prove that the internal electric field promotes the desorption of hydrogen on Pd. Pd/TBT(C)@SC-800 obtained by heat treatment at 800 °C, with the optimal internal electric field strength, exhibits high activity and hydrogen selectivity for FAD. This work provides a new strategy for designing FAD catalysts.

Production of continuous nanofiber bundles by multi parallel electrodes in needleless electrospinning

This study explores the collection of nanofiber bundles on a conveyor belt for continuous production, contrasting with previous studies that focused on the production of limited-length nanofibers directly on electrodes. The research focuses on examining how the plate width and the gap distance within a conveyor system influence the alignment and morphology of the nanofibers. To fully understand these effects, the designs of multi parallel electrodes were analyzed using COMSOL Multiphysics. This analysis focused on determining the electric field strength, the electrical potential, and the vectors of the electric field within these systems. Additionally, the study delved into the alignment and morphology of the polyacrylonitrile nanofibers, employing a field emission scanning electron microscope for detailed observation. The findings revealed that both the width of the plates and the gap distance critically impacted the alignment and nanofiber morphology. The optimal alignment and uniformity of nanofibers were achieved at specific plate widths and gap distances, demonstrating the intricate relationship between these parameters and nanofiber characteristics.

Comparative analysis of installations for heat treatment of non-food pulp raw materials by the influence of electrophysical factors

Relevance. The objectives of the work are to develop radio-hermetic installations and substantiate the effective design of the working chamber, which provides a comprehensive effect of electrophysical factors on non-food pulp raw materials to preserve feed value at reduced operating costs. Scientific tasks: 1) to develop installations with different designs of resonators; 2) to conduct a comparative analysis of the working chambers according to the main parameters; 3) to evaluate the technical and economic indicators of an effective installation in relation to the basic version.Methods. The effect of electrophysical factors on raw materials is realized in resonators with magnetrons and frequency generators of pulse-modeled high-frequency oscillations of 110 kHz, where a bactericidal flux lamp serves as a high-potential electrode.Results. Several continuous-flow radiohermetic installations with ultrahigh-frequency (microwave) power supply to non-standard resonators have been developed, inside which a complex effect of a high-intensity electric field, a bactericidal flow of UV rays and ozone is realized to reduce bacterial contamination of the product and neutralize odor during heat treatment of raw materials, the dimensions of which are consistent with the depth of penetration of the wave. Features of conical and biconic resonators − provide radio leakage in continuous operation by cutting off the tip at the level of the critical section, depending on the angle of inclination of the cone generator, and allow you to keep the standing wave inside the resonator. The combination of magnetron and cylindrical resonators increases the efficiency of the interaction of the electron flux with the microwave field, and an increase in the inductive volume, which is a “reservoir” of energy, increases the intrinsic quality of the resonator. A quasi-toroidal resonator, presented as a conical resonator in a toroidal resonator, having small overall dimensions and metal consumption, provides a traveling wave in the annular space, and a standing wave in the conical space. The high electric field strength in the capacitor part of the resonator and the corona discharge in the torus contribute to the disinfection of raw materials.

Effects of Static Electric Fields on the Excitations of Silver Nanowire Dimers.

We theoretically studied the introduction of static electric fields to Ag10 nanowire dimer systems, including the effects of this field on optical absorption characteristics and the orbitals responsible for these excitations. Linear-response time-dependent density functional theory computations were performed on three distinct dimer systems: end-to-end, parallel, and 90° angle dimer systems separated by a closest interparticle distance of 7.0 Å. The calculations were performed in the presence of a 0.1 V/Å electric field strength applied in the z and y directions. The orientation of the dimer system and the direction of the applied static electric field each play a significant role in the resulting absorption spectra and the electronic structure of the nanowires. As a result, a dimer system can exhibit a blue shift for the longitudinal excitation and a red shift for the transverse excitation in the presence of one direction of the static electric field but not for the other direction. Notably, the electron density shifts from one nanowire to the other in the presence of the static electric field. Changes in optical characteristics and electronic structure suggest that the usage of a static electric field with a particular spatial configuration of nanowires provides a way to tune the optical properties of the system.

Non‐coalescence of nonidentical droplets in oil under a DC electric field

AbstractExcessive electric field strength causes the droplets to contact but not coalesce, severely deteriorating the oil–water separation efficiency. The investigation of the non‐coalescence of nonidentical droplets in oil under a DC electric field is conducted using high‐speed photography. The effects of droplet volume ratio and interfacial tension ratio on the characteristics and critical parameters for droplet non‐coalescence are systematically explored. The results show the critical electrocapillary number for the non‐coalescence of nonidentical droplets and critical contact cone angle decreases as the volume sum increases or the interfacial tension ratio decreases, which is related to the competition between the resultant electric field force and the interfacial tension force. These results contribute to optimizing the operating parameters of the electric coalescer and improving the oil–water separation efficiency.

Electric field-induced clustering in nanocomposite films of highly polarizable inclusions

A nanocomposite film containing highly polarizable inclusions in a fluid background is explored when an external electric field is applied perpendicular to the planar film. For small electric fields, the induced dipole moments of the inclusions are all polarized in field direction, resulting in a mutual repulsion between the inclusions. Here we show that this becomes qualitatively different for high fields: the total system self-organizes into a state which contains both polarizations, parallel and antiparallel to the external field such that a fraction of the inclusions is counter-polarized to the electric field direction. We attribute this unexpected counter-polarization to the presence of neighboring dipoles which are highly polarized and locally revert the direction of the total electric field. Since dipoles with opposite moments are attractive, the system shows a wealth of novel equilibrium structures for varied inclusion density and electric field strength. These include fluids and solids with homogeneous polarizations as well as equilibrium clusters and demixed states with two different polarization signatures. Based on computer simulations of an linearized polarization model, our results can guide the control of nanocomposites for various applications, including sensing external fields, directing light within plasmonic materials, and controlling the functionality of biological membranes.

Iota‐carrageenan (𝑖C) hydrogel oscillations under constant electric field and stability diagrams

AbstractSoft actuators belong to a type of actuators made of soft materials which are capable of converting applied energy to mechanical motion. They have been utilized in several fields due to their flexibility, low weight, inexpensiveness and simple fabrication. In this work, iota‐carrageenan (𝑖C) was chosen as the starting material for a hydrogel‐based actuator. The 𝑖C hydrogels were fabricated via a simple solvent‐casting technique at various concentrations: 2.4% (v/v), 2.8% (v/v) and 3.2% (v/v). All 𝑖C hydrogels were characterized for their chemical, thermal, rheological and morphological properties as well as the actuation performances under applied electric field. The 𝑖C hydrogels showed monotonic increases in the static bending distance and dielectrophoretic force with increasing electric field strength. Above the critical electrical field strengths, the ribbon‐like 𝑖C hydrogels oscillated back and forth due to the competition between the dielectrophoresis force, the resisting elastic force, the weight and the inertia force. Stability diagrams were constructed for the first time separating static bending from oscillation behavior under constant applied electric fields. © 2024 Society of Chemical Industry.

Precise surface machining of fused silica using high stability atmospheric pressure microwave plasma jet with a new internal electrode

Plasma is a promising approach for machining of fused glass substrates. Developing high-performance microwave torch is the core element to ensure the processing accuracy of this technology. In this study, a spline curve-based microwave torch internal electrode structure was proposed, which increased the internal electric field strength by 54 %. The discharge dynamics simulation based on this electrode shows that the plasma is excited at the inner electrode tip and the bottom of the resonant cavity, then it expands to form a linear discharge region and eventually fill the discharge tube. It was revealed by CCD images that with the increase of carrier gas flow rate, turbulent flow state appears in the tail of the jet. OES data shows that microwave Ar plasma can effectively dissociate CF4, and due to the oxidation effect of oxygen, CFx and C2 content decrease significantly with the addition of oxygen. The machining experiment on fused silica shows that the material removal stability of this torch reaches 3.69 %, and the removal rate increases nYarly with dwell time due to thermal effect. Finally, the machining performance of the atmospheric pressure microwave plasma jet was verified by figuring of a planar fused silica surface reducing the form error from 108.1 nm RMS to 16.5 nm RMS.

A Review of β-Ga2O3 Power Diodes.

As the most stable phase of gallium oxide, β-Ga2O3 can enable high-quality, large-size, low-cost, and controllably doped wafers by the melt method. It also features a bandgap of 4.7-4.9 eV, a critical electric field strength of 8 MV/cm, and a Baliga's figure of merit (BFOM) of up to 3444, which is 10 and 4 times higher than that of SiC and GaN, respectively, showing great potential for application in power devices. However, the lack of effective p-type Ga2O3 limits the development of bipolar devices. Most research has focused on unipolar devices, with breakthroughs in recent years. This review mainly summarizes the research progress fora different structures of β-Ga2O3 power diodes and gives a brief introduction to their thermal management and circuit applications.

Unraveling the influence of nitration on pore formation time in electroporation of cell membranes: a molecular dynamics simulation approach

Electroporation, the transient permeabilization of cell membranes induced by electric fields, is an essential technique in biomedicine, facilitating gene delivery, drug transport, and cancer therapy. Despite its wide application, the influence of nitration, a biological modification involving the addition of nitro groups to phospholipids, on electroporation dynamics remains understudied. Here, we employ molecular dynamics simulations to investigate the impact of nitration on pore formation during electroporation. By systematically varying nitration levels and electric field strengths, we explore the nuanced interplay between nitration and electroporation kinetics. Our simulations reveal that increasing nitration levels significantly accelerate pore formation, with notable reductions in pore formation times observed at higher nitration percentages and stronger electric fields. This phenomenon underscores the modulatory role of nitration in altering the dynamics of electroporation. Additionally, our study sheds light on the intricate mechanisms underlying this process, providing essential insights for optimizing electroporation protocols in gene therapy, drug delivery, plasma cancer treatment and related biomedical applications. These findings illuminate the synergistic relationship between nitration and electroporation, paving the way for future advancements in this vital field.

Application of pulsed electric field technology to skin engineering.

Tissue engineering encompasses a range of techniques that direct the growth of cells into a living tissue construct for regenerative medicine applications, disease models, drug discovery, and safety testing. These techniques have been implemented to alleviate the clinical burdens of impaired healing of skin, bone, and other tissues. Construct development requires the integration of tissue-specific cells and/or an extracellular matrix-mimicking biomaterial for structural support. Production of such constructs is generally expensive and environmentally costly, thus eco-sustainable approaches should be explored. Pulsed electric field (PEF) technology is a nonthermal physical processing method commonly used in food production and biomedical applications. In this review, the key principles of PEF and the application of PEF technology for skin engineering will be discussed, with an emphasis on how PEF can be applied to skin cells to modify their behaviour, and to biomaterials to assist in their isolation or sterilisation, or to modify their physical properties. The findings indicate that the success of PEF in tissue engineering will be reliant on systematic evaluation of key parameters, such as electric field strength, and their impact on different skin cell and biomaterial types. Linking tangible input parameters to biological responses critical to healing will assist with the development of PEF as a sustainable tool for skin repair and other tissue engineering applications.

Difference between endocardial and epicardial application of pulsed fields for targeting Epicardial Ganglia: An in-silico modelling study

BackgroundPulsed Field Ablation (PFA) has recently been proposed as a non-thermal energy to treat atrial fibrillation by selective ablation of ganglionated plexi (GP) embedded in epicardial fat. While some of PFA-technologies use an endocardial approach, others use epicardial access with promising pre-clinical results. However, as each technology uses a different and sometimes proprietary pulse application protocol, the comparation between endocardial vs. epicardial approach is almost impossible in experimental terms. For this reason, our study, based on a computational model, allows a direct comparison of electric field distribution and thermal-side effects of both approaches under equal conditions in terms of electrode design, pulse protocol and anatomical characteristics of the tissues involved. Methods2D computational models with axial symmetry were built for endocardial and epicardial approaches. Atrial (1.5−2.5 mm) and fat (1−5 mm) thicknesses were varied to simulate a representative sample of what happens during PFA ablation for different applied voltage values (1000, 1500 and 2000 V) and number of pulses (30 and 50). ResultsThe epicardial approach was superior for capturing greater volumes of fat when the applied voltage was increased: 231 mm3/kV with the epicardial approach vs. 182 mm3/kV with the endocardial approach. In relation to collateral damage to the myocardium, the epicardial approach considerably spares the myocardium, unlike what happens with the endocardial approach. Although the epicardial approach caused much more thermal damage in the fat, there is not a significant difference between the approaches in terms of size of thermal damage in the myocardium. ConclusionsOur results suggest that epicardial PFA ablation of GPs is more effective than an endocardial approach. The proximity and directionality of the electric field deposited using an epicardial approach are key to ensuring that higher electric field strengths and increased temperatures are obtained within the epicardial fat, thus contributing to selective ablation of the GPs with minimal myocardial damage.