Variation Of Electric Field Research Articles

Dependence of the surface tension and contact angle on the temperature, as described by the diffuse-interface model.

Four results associated with the diffuse-interface model (DIM) for contact lines are reported in this paper. First, a boundary condition is derived, which states that the fluid near a solid wall must have a certain density ρ_{0} depending on the solid's properties. Unlike previous derivations, the one presented here is based on the same physics as the DIM itself and does not require additional assumptions. Second, asymptotic estimates are used to check a conjecture lying at the foundation of the DIM, as well as all other models of contact lines, that liquid-vapor interfaces are nearly isothermal. It turns out that, for water, they are not, although, for a more viscous fluid, they can be. The nonisothermality occurs locally, near the interface, but can still affect the contact-line dynamics. Third, the DIM coupled with a realistic equation of state for water is used to compute the dependence of the surface tension σ on the temperature T, which agrees well with the empirical σ(T). Fourth, the same framework is used to compute the static contact angle of a water-vapor interface. It is shown that, with increasing temperature, the contact angle becomes either 180^{∘} (perfect hydrophobicity) or 0^{∘} (perfect hydrophilicity), depending on whether ρ_{0} matches the density of saturated vapor or liquid, respectively. Such behavior presumably occurs in all fluids, not just water, and for all sufficiently strong variations of parameters, not just that of the temperature, as corroborated by existing observations of drops under variable electric field.

Microwave imaging of breast cancer with factorization method: SPIONs as contrast agent.

We demonstrate an imaging technique that can locate cancerous tumors inside the breast due to electric field variations caused by SPION tracers under different magnetic field intensities. Furthermore, we assess the feasibility of SPION-enhanced microwave imaging for breast cancer with simulations performed on a multi-static imaging configuration. The imaging procedure is realized as the factorization method of qualitative inverse scattering theory, which is essentially a shape retrieval algorithm for inaccessible objects. The formulation is heuristically modified to accommodate the scattering parameters instead of the electric field to comply with the requirements of experimental microwave imaging systems. With full-wave electromagnetic simulations performed on an anthropomorphically realistic breast phantom, which is excited with a cylindrical imaging prototype of 18 dipole antenna arranged as a single row, the technique is able to locate cancerous tumors for a experimentally achievable doses. The technique generates nonanatomic microwave images, which map the cancerous tumors depending on the concentration of SPION tracers, to aid the diagnosis of the breast cancer.

Flare Energy Release at the Magnetic Field Polarity Inversion Line during the M1.2 Solar Flare of 2015 March 15. II. Investigation of Photospheric Electric Current and Magnetic Field Variations Using HMI 135 s Vector Magnetograms

Abstract This work is a continuation of Paper I and is devoted to the analysis of nonthermal electron dynamics and plasma heating in the confined M1.2 class solar flare SOL2015-03-15T22:43, revealing energy release in the highly sheared interacting magnetic loops in the low corona, above the polarity inversion line (PIL). The aim of the present work is to perform the first extensive quantitative analysis of the photospheric magnetic field and photospheric vertical electric current (PVEC) dynamics in the confined flare region near the PIL using new vector magnetograms obtained with the Helioseismic and Magnetic Imager on board the Solar Dynamics Observatory with a high temporal resolution of 135 s. Data analysis reveals sharp changes of the magnetic structure and PVEC associated with flare onset near the PIL. It is found that the strongest plasma heating and electron acceleration are associated with the largest increase in the magnetic reconnection rate, total PVEC, and effective PVEC density in the flare ribbons. Observations and nonlinear force-free field extrapolations show that the magnetic field structure around the PIL is consistent with a tether-cutting magnetic reconnection (TCMR) geometry. We give a qualitative interpretation of the observed dynamics of the flare ribbons, magnetic field, PVEC, and electron acceleration within the TCMR scenario.

Modeling the inactivation of Escherichia coli O157:H7 and Salmonella Typhimurium in juices by pulsed electric fields: The role of the energy density

This study groups together pulse electric field variables such as electric field intensity, pulse repetition rate, treatment time, and electrical conductivity of food in a single integrated energy density parameter and correlate it with the inactivation rate of Escherichia coli O157:H7 and Salmonella Typhimurium. A continuous bench scale PEF system (OSU–4H) was used to treat juice samples with the combinations of 5 electric field strengths and 5 pulse repetition rates. Nonlinear survival curves were modeled by numerically solving a differential equation by the Runge-Kutta method. The developed model successfully described the survival kinetics of the involved pathogens. The model was validated with different juices and PEF treatments and demonstrated that it was able to satisfactorily predict the experimental data as well as data from literature. These predictions suggest that the model is suitable for precisely estimating the inactivation rate of foodborne pathogens of concern in juices by PEF processing.

Local and global effects on the diurnal variation of the atmospheric electric field in South America by comparison with the Carnegie curve

The study of the global atmospheric electric circuit is important to understand the climate system and this can be done by monitoring the atmospheric electric field worldwide. In this way, continuous measurements of atmospheric electric field are being recorded by the Atmospheric electric FIeld Network in South America (AFINSA). The main objective of this network is to obtain the daily curve of atmospheric electric field variations under fair weather conditions for each station, through monthly, seasonal and annual averages. These curves are called ‘standard curves’. In this paper, we compare and analyze the monthly, seasonal and annual standard curves for each sensor location. The results indicate significant similarities and differences between the annual standard curve and the Carnegie curve. The similarities, with correlation r ≥ 0.9 for most stations, are associated with a global representation of the global electrical circuit and the differences due to local effects, such as ‘Austausch’ effect and pollution. • A new network to monitor the atmospheric electric field on the ground. • Global and local contribution are found in the electric field standard curves. • Annual standard curves have a high correlation with the ‘universal’ Carnegie curve.

Design, Modeling and Simulation of a Capacitive Size-Discriminating Particulate Matter Sensor for Personal Air Quality Monitoring

We applied the well-established thermophoretic effect to air quality monitoring. We developed a novel method for particulate matter distribution analysis in an in-flow capacitive detection device. The proposed Multiphysics model combines fluid dynamics of particulate matter influenced by thermophoresis with electric field variations in the active volume space of a charged coplanar interdigitated electrodes. The model allows to anticipate the effect of thermophoresis in separating particles of PM10 and PM2.5 size ranges into different streams from a single particle-entrained flow and provides an estimated value of sensitivity for capacitive PM detection. The model is described through the Finite Element Method from the main equations to the simulation run using COMSOL Multiphysics and validated by comparing the results with literature. We obtained high sensor sensitivity of up to 0.48 zF/particle as far as $18~\mu \text{m}$ from coplanar electrode surface using the Computational Fluid Dynamics and Heat Transfer, Electrostatics and Particle tracing modules. We compare results of the simulations for different particle positions, electrode width and inter-electrode spacing, then we use the results to identify optimal design parameters for a novel architecture of a PM detection system with high sensitivity down to PM2.5 single particles and embedded particle size discrimination by using $10~\mu \text{m}$ electrode width and $1\mu \text{m}$ inter-electrode spacing.

Structural, Optical, and Multiferroic Properties of Yttrium (Y3+)-Substituted BiFeO3 Nanostructures

Nanoparticles of Bi1-xYxFeO3 (x = 0.0, 0.1, 0.15, 0.2) were synthesized by sol-gel pursued auto-combustion route. X-ray diffraction (XRD) pattern was recorded for analysis of the phase formation of pristine BiFeO3 (BFO) and Y3+-substituted samples. A systematic decrease in crystallite size with increasing concentration of Y3+ was observed by XRD and W-H plot. FESEM micrograph demonstrated clearly that the average grain size is decreased with increasing Y3+ ion concentration. Compositional analysis was carried out by EDS. Optical properties of the developed nanoparticles were examined by diffuse reflectance spectroscopy; it is observed that optical band gap decreases with increase in Y3+ ion concentration. Vibrating sample magnetometer (VSM) analysis revealed weak ferromagnetic behavior for pristine BFO. The ferromagnetic behavior has been enhanced with increasing concentration of Y3+ ions in BFO. Temperature dependence of dielectric constant shows an anomaly near the antiferromagnetic transition temperature in the developed materials that revealed the existence of magnetoelectric coupling in all the samples. Improved ferroelectric property has been observed by virtue of enhancement in the polarization of all substituted samples. Variation of electric field–guided strain with applied electric field has shown asymmetric behavior for samples x ≤ 0.15 and symmetric loop has been observed for x = 0.2 with the highest peak to peak strain value which makes it active material for electronic and magnetic devices.

Simulation of nanodielectrics: nanoparticle and interphase effects on electric field distributions

Nanodielectrics have been regarded as a class of material system that can provide significantly improved chemical, mechanical and dielectric properties over conventional microcomposites. This is due to the presence of a high volume fraction of the interphase between nanoparticles and polymers. However, precise effects of nanodielectrics are not well understood, leading to difficulties in interpreting the dielectric behaviours of nanodielectrics. In the current work, effects of nanoparticle distributions, interparticle distances, nanoparticle sizes, interphase permittivities and interphase thicknesses on the possible electric field variations within a nanodielectric model have been simulated using Finite Element Method Magnetics (FEMM) 4.2. The results demonstrate that different nanoparticle and interphase configurations lead to different effects on the electric field intensity within the nanodielectric model. Mechanisms leading to changes in dielectric properties based on the observed electric field variations are discussed.

On electrohydrodynamic flow of Jeffrey fluid through a heating vibrating cylindrical tube with moving endoscope

This paper deals with the study of the effect of a variable normal electric field on Jeffry flow through a heating vibrating cylindrical tube with moving endoscope. Under the assumption of long wavelength and the use of appropriate non-dimensional quantities, the analytical solutions for axial and radial velocities, stream function, fluid pressure, electrical potential function and temperature distribution are obtained. The results show that the volume of the trapped bolus increases by the increase of amplitude ratio, endoscope radius, Jeffry parameter and electrical Rayleigh number, whereas it has an opposite effect on the increase in the endoscope velocity and temperature parameter. Furthermore, it is observed that the effects of the amplitude ratio and Jeffry parameter on the axial velocity in the presence of electric field are greater and clearer than those in the absence of electric field.

Spatial Variability of Electric Field Implied by Common Dielectric Effective Medium Models

Remote sensing measurements of Earth materials are always made at scales much larger than individual grains and cavities, yielding only upscaled effective properties. An “effective medium” is an idealized uniform material that has the same measured properties as the real mixture. A uniform electric field applied to the ideal effective medium remains uniform within the sample; however, the same electric field applied to the composite results in fine-scale spatial variations of field strength within the sample, which depend on the properties of the constituents, their volume fractions, and their microgeometries. We derived analytic expressions for the electric field strength heterogeneity implicit in commonly used dielectric effective medium models. Only two-phase, statistically isotropic, low-loss materials, e.g., ice, snow, minerals, and freshwater in the microwave UHF band are considered. The method applies to singly or biconnected phases. The results confirm the uniform field in the isolated phase of material lying on the Hashin–Shtrikman (HS) bounds; the continuous phase field variance increases with a decreasing volume fraction, approaching a well-defined limit as the fraction becomes vanishingly small. Expressions are found for field variance in higher-order composites of coated spheres, providing realizations of composites lying between the HS bounds, and illustrating field nonuniqueness when microstructure is unknown. The mean and variance of the field strength in popular effective medium models are also examined. Not only do the effective properties predicted by these models differ so do the electric field strength spatial variability, especially when the volume fraction of inclusions increases.

Design of a large aperture, tunable, Pancharatnam phase beam steering device.

Replacing mechanical optical beam steering devices with non-mechanical electro-optic devices has been a long-standing desire for applications such as space-based communication, LiDAR and autonomous vehicles. While promising progress has been achieved to non-mechanically deflect light with high efficiency over a wide angular range, significant limitations remain towards achieving large aperture beam steering with a tunable steering direction. In this paper, we propose a unique liquid crystal based Pancharatnam Phase Device for beam steering which can provide both tunability and a fast response times in a format scalable to large apertures. This architecture employs a linear array of phase control elements to locally control the orientation of the liquid crystal director into a cycloidal pattern to deflect transmitted light. The PCEs are comprised of a fringe field switching electrode structure that can provide a variable in-plane electric field. Detailed modeling of the proposed design is presented which demonstrates that such a device can achieve a high degree of uniformity as it rotates the LC molecules over the 180 ° angular range required to create a Pancharatnam phase device.

Individual Targeting Increases Control Over Inter-Individual Variability in Simulated Transcranial Electric Fields

Transcranial electric stimulation (tES) induces electric fields that propagate in the brain and depend on individual anatomies. The interaction between the electric fields and individual anatomies may contribute to the heterogenous results that are commonly observed across tES studies in humans. Targeted tES is able to account for some of these individual factors by adapting the electric field to the stimulation target. Here, the effect of individually targeted tES on simulated intracranial electric fields was evaluated in head models of twenty-one participants using the finite-element method (FEM). For all participants, two individually targeted tES montages were compared to a fixed stimulation montage that was not individually optimized. For a simulated parietal stimulation target with three different orientations, individual current densities showed varying intensities near the lower limit at which physiological efficacy of electric fields can be assumed. However, targeting algorithms were able to control different electric field properties, by either maximizing the target current densities or by increasing the specificity of electric fields with respect to target location and orientation. Electric fields were constrained by individual anatomical properties, but still showed considerable variation for the given parietal stimulation target across participants. Thus, we present findings of inter-individual variability within the same cortical region to complement recent studies that showed large variation across cortical regions in a single FEM head model. Our results support the usage of individual targeting for enhancing the efficacy of tES and for elucidating the underlying mechanisms of tES. At the same time, residual variability in electric fields is suggested to be utilized for the explanation of individual differences in the tES outcome.

Response of piezoelectric materials to the external temperature, electric field and humidity

Piezoelectric materials are smart the materials that possess piezoelectric property. A piezoelectric material can convert electric input to mechanical output and vice versa. There are varieties of piezoelectric materials available and their behaviour to the input is dependent on the external environmental factors. In this paper properties of various piezoelectric materials are discussed and reproduced using MATLAB® software. Variation of piezoelectric strain coefficient and dielectric constant with variation in temperature, electric field and humidity are shown in figures. Ready to use tables are also made for different piezoelectric materials for piezoelectric strain coefficient and dielectric constant at different temperature and electric field (using curve fit method in MATLAB®).

О ВЕРОЯТНЫХ МЕХАНИЗМАХ ВЗАИМОДЕЙСТВИЯ ПЕРЕМЕННЫХ ЭЛЕКТРИЧЕСКИХ ПОЛЕЙ С ЖИДКОСТЯМИ РАЗЛИЧНОЙ ПОЛЯРНОСТИ

An attempt was made to systematize and generalize the results of our own experiments, as well as available information on the impact of variable low-frequency electric fields on liquids of different polarities. The influence of the electrophysical impact was revealed on the examples of polar substances (containing hydrogen bonds) – water, ethanol, octane-non-polar alkane. The probable mechanism and forecast of practical use of those effects on a number of substances of different polarities were proposed. The article is debatable.

Negative Capacitance Effect on MOS Structure: Influence of Electric Field Variation

We explicate the negative capacitance (NC) effect in MOS structures through TCAD simulation, and find the influence of electric field variation in ferroelectric layer. Furthermore, pre-researched time-dependent NC effect is explained in more detail. For this purpose, the electric field and potential difference in the ferroelectric layer are analyzed based on the measured data of metal-ferroelectric-metal (MFM) capacitors, and then the parameters for the occurrence of the NC effect in the NCFET were analyzed. This establishes the conditions necessary for the successful operation of the NCFET.

Electric Field Mill, an Effective Methodology to Measure the Localized Lower Atmospheric Electric Field

Atmospheric electric field is an utmost parameter to study the dynamics of earth’s atmosphere. Response of electric field may give the idea of localized atmospheric agitations. Electric field mill monitoring system monitors the atmospheric electric field variations which help to investigate and characterize the atmospheric variability in dissimilar weather conditions including thunderstorm, rainfall, lightning and alarming condition of seismic activities. Different patterns of atmospheric electric field pertains the various climatic conditions. The objective of EFM is to provide the nearly continuous survey of atmospheric electric field which may arise due to the coupling of atmospheric perturbations in lower earth atmosphere hence causing the changes in the complexities of the localized atmospheric electric field

A New Framework to Incorporate High‐Latitude Input for Mesoscale Electrodynamics

AbstractGlobal circulation models (GCMs) for the ionosphere‐thermosphere system traditionally use empirical models to specify upper boundary conditions to represent solar wind and magnetospheric drivers. However, the magnetosphere, ionosphere, and thermosphere systems are coupled on different spatial and temporal scales. During increased levels of geomagnetic activity, these empirical models can't resolve dynamic electric field variability ( 500 km, 15 min) because of their statistical nature and/or low spatial and temporal resolutions. This results in an underestimation of energy input to the ionosphere, causing disagreements between model results and observations. This paper introduces a new framework to incorporate dynamic electric fields into GCMs: High‐latitude Input for Mesoscale Electrodynamics (HIME). As a demonstration HIME uses the Poker Flat Incoherent Scatter Radar (PFISR) electric field estimates during an experiment on 2 March 2017. The electric potentials were calculated using the PFISR estimates and merged with a global empirical model of electric potential. A set of high‐latitude electric potential drivers were used to drive the University of Michigan Global Ionosphere Thermosphere Model (GITM) to understand the effects of driving at different scales. Data versus model comparisons for ion temperature, electron temperature, and electron density are provided along the PFISR beams. The ion convection velocities and neutral winds at the PFISR location are compared with the PFISR and Scanning Doppler Imager data. The effects of different multiscale drivers are investigated. The results showed that energy deposited by HIME‐driven simulations was locally larger by approximately an order of magnitude compared to the empirical model‐driven results.

Observing the formation of zero-mean circular Gaussian statistics in two-dimensional random media

Abstract Zero-mean circular Gaussian statistics is a well-known model for coherent electromagnetic wave scattered by random media. Applying Kullback-Leibler Divergence to measure the deviation of the simulation scattering field probability distribution from this model, the formation of zero-mean circular Gaussian statistics is investigated quantitatively in two-dimensional random media based on finite element method. Increasing the scattering and randomness in the media, the transmission electric field gradually approaches zero-mean circular Gaussian statistics, however, the deviation from a perfect statistics distribution has a limit which is only determined by the number of random electric field variables used for estimates the probability distribution; besides, field amplitude forming stable statistics faster than field phase.

EMBEDDED PARTICULATE BIOMATERIALS AS DIELECTRIC FILLERS IN ELECTROACTIVE NATURAL RUBBER COMPOSITES

ABSTRACT Both eggshell and eggshell membrane are potential alternative dielectric biomaterials because of their inorganic and organic matter contents, respectively. Adding eggshell or eggshell membrane into natural rubber compounds made using the sulfur curing system has many advantages such as flexibility, ease of formation, ability to operate under large strains and shape conformability, lightweight, and low cost of production. The results indicated that the natural rubber composite had a rubberlike characteristic and good elasticity. Both the eggshell and eggshell membrane acted as a dispersed-phase or dielectric filler that can absorb and store additional stress effects, resulting in fast curing and increasing crosslink density. Under a variable electrical field, eggshell and eggshell membrane particles induced dipolar moments and led to interparticle interactions that increased the storage modulus response substantially by nearly two orders of magnitude at 1.5 kV/mm. The obtained natural rubber composites can contribute toward more effective polarization and hence stronger electrostatic interactions between the embedded particles, resulting in a fast deflection response due to the dielectrophoresis force generation at low electrical field strengths of 300 and 350 V/mm for eggshell and eggshell membrane, respectively. The additional advantage of eggshell waste utilization is welcome as a means of reducing global climate warming and adding value to eggshell waste.

OPPORTUNITIES FOR THE APPLICATION OF A FREQUENCY MODULATED ELECTRIC FIELD SIGNAL FOR TREATING BURNS AND THE RAS

The paper presents the results of an experimental study on the effect of a variable frequency-modulated electric field on the course of a wound process in a burn wound. The evaluation of the effectiveness of the antimicrobial action of wound healing agents against the background of an alternating frequency-modulated electric field has been carried out. The bacteriostatic effect of some wound healing agents used in combination with electrical physical and antiseptic action has been proven.