Electric Potential Distribution Research Articles

Diffusion calculations on reconstructed bentonite microstructures with anion exclusion effects.

Due to their prevalence in the lithosphere and their high capability of sorbing pollutants, smectite clays play a foreground role in environmental pollution studies, waste management, and soil science. In complementarity with existing approaches at the molecular or macroscopic scales, real microstructures have been employed to investigate ionic transport by diffusion through montmorillonite and water-saturated Wyoming bentonite at intermediate scales ranging between the nanometer and the micrometer. The coupled solute transport and electrostatic phenomena investigated at the nanopore scale are upscaled using the homogenization of porous media approach. Homogenization computations rely on a hierarchical description of bentonite that acknowledges the existence of pores networks at different scales. At the scale of montmorillonite layers, digitized TEM images have been employed to simulate the diffusion of ionic solutes by considering electrostatic interactions in the vicinity of the negatively charged clay platelets' surface. Finite element microstructures are created after extraction of the contours of the layers using dedicated image processing algorithms. Local electric potential distribution, anion exclusion, and cation inclusion are displayed by ion distribution maps. The effective diffusion tensor and the transport equation obtained through volume averaging are then used to simulate diffusion at the scale of a Wyoming bentonite sample composed of clay gels of variable density, solid grains, and micropores. Qualitative comparisons were made with existing diffusion data, and a particular attention is given to the anisotropy of the diffusion tensors at both the mesoscopic and macroscopic scales.

Analysis of Electroosmotically Modulated Peristaltic Transport of Third Grade Fluid in a Microtube Considering Slip-Dependent Zeta Potential

Abstract The present study investigates electro-osmotically modulated peristaltic transport of third-grade fluid through a microtube taking into consideration the intricate coupling of zeta potential and hydrodynamic slippage. The analytical results encompass the mathematical expressions for dimensionless electrical potential distribution as well as series solutions for stream function and axial pressure gradient up to first order utilizing the perturbation technique for small Deborah number coupled with the Cauchy product for infinite series. Critical values and ranges of wavelength have been obtained where the axial pressure gradient vanishes. Moreover, pivotal values and ranges of wavelength have also been noted for the invariance of pressure gradient with respect to Deborah number as well as Debye–Hückel parameter. Trapping phenomenon has also been investigated by contours of streamlines wherein the zones of recirculation or trapped boluses are formed predominantly near the microtube walls. Additionally, the relative enhancement in hydrodynamic slippage amplifies the trapped bolus size, whereas a diminishing behavior on bolus size is observed by the electro-osmotic parameter.

Silane-modified MXene/PVA hydrogel for enhanced streaming vibration potential in high-performance flexible triboelectric nanogenerators

To meet the growing demand for flexible, self-powered, and portable electronic devices—vital for advancing soft robots, electronic skins, and energy-harvesting technologies—we've refined our approach to creating polyvinyl alcohol (PVA) modulating polyethylene glycol (PEG) to facilitate cation movement along polymer chains, significantly boosting the hydrogel's performance in triboelectric nanogenerators (PPh TENG), which is further enhanced by adding with layered Ti3C2 nanosheets, serving as ionic conductors. These nanosheets introduce an efficient electrostatic mechanism known as the streaming vibration potential (SVP), significantly augmenting the device's functionality. Moreover, we used 3-chloropropyltrimethoxysilane (CPTMS) and 1 H, 1 H, 2 H, 2 H-perfluorooctyltriethoxysilane (FOTS) to modify the surface of MXene nanosheets to fabricate Cl-MXene and F-MXene hydrogel TENGs, as named by Cl-MPPh and F-MPPh TENGs, respectively. The SVP effect is enhanced by these modified MXene nanosheets in the hydrogel, which is more substantial than unmodified MXene nanosheets. This is attributed to the higher charge density in the electric double layer formed between the MXene nanosheets and water. The Cl-MPPh and F-MPPh TENGs demonstrate open-circuit voltages of 190 V and 212 V, respectively. Our theoretical calculations show a marked increase in the distribution of electric potential. This increase occurs on both sides of the MXene nanosheets as water molecules move through them. The F-MPPh TENG exhibits exceptional sensitivity to mechanical stimuli, which holds promising potential for integration into motion sensors designed to monitor human body movements, including the bending of elbows and wrists.

Periodic electroosmotic flow of nanofluids with slip-dependent high zeta potential

The time periodic electroosmotic flow of nanofluids is investigated analytically in a hydrophobic microchannel. In this study, we consider the interdependence relationship between the wall electrical potential and slip. According to the non-linear slip-dependent zeta potential, we obtain an analytical solution of electrical potential for arbitrary value of wall electrical potential. Subsequently, we give the analytical integration expression of time periodic electroosmotic velocity of nanofluids. Based on the obtained electrical potential distribution, the oscillating flow velocity and rate are calculated numerically. The flow characteristics are determined by the oscillating frequency of electrical field, the volume fraction of nanoparticles and wall electrical potential. The noteworthy results are that, the oscillating electrical field can result in the oscillation of nanofluids. However, such oscillation is strongly dependent on the electrical field frequency and the flow characteristics are significantly different for various frequencies. Moreover, when the nanoparticles are introduced into the time periodic electroosmotic flow, the oscillation can be restrained. This may be helpful to understand the electrohydrodynamic instability of nanofluids.

Capacitive Sensor for Monitoring the Condition of Suspended High-Voltage Insulation

The purpose of the work is to develop the design of a sensor for monitoring the condition of high-voltage power lines suspended insulation. To achieve this goal, a diagnostic criterion was selected, the operating principle and design of the insulation monitoring sensor were determined. As a diagnostic criterion is considered a changing of voltage on the insulator plate due to a change in the distribution of electrical potential on the insulators, caused of damage in the insulators string. For the diagnostic system implementation was adopted a sensor based on a capacitive divider. The calculations confirm the pos-sibility of registration a damaged element in a insulators string by getting of voltage change at the sen-sors output. The calculation results were verified by modeling in the Multisim software. The parameters of the sensor were calculated, correctness of it is confirmed by the results of laboratory measurements of the new insulators plate capacitances, as well as insulators destroyed as a result of operation. The most important results of the research are the selection of the optimal diagnostic criterion and research-ing of the proposed design sensor effectiveness for assessing the suspended insulation condition. The significance of the results obtained lies in the fact that the developed design of a sensor allows one to obtain prompt information about the presence of damage in the insulation. The use of the proposed sensor design will make possible creation a continuous diagnostic system and identify damage at an early stage, which will ensure timely maintenance.

DC-driven subatmospheric glow discharges in the infrared-stimulated

This paper presents a conceptual framework for experimental research combined with numerical analysis on direct current (DC) glow discharges in microscale planar gas discharge-semiconductor systems (GDSS). In the experimental section, several structural and elemental analyses, including SEM, EDAX, AFM, and near-infrared absorption spectra measurements were carried out for compound semiconductor zinc selenide (ZnSe) cathode sample. Argon (Ar) was charged into the plasma reactor cell of GDSS at pressures of 100 Torr subatmospheric and 760 Torr atmospheric, respectively, by a vacuum pump- gas filling station. Glow discharge light emissions from plasma, excited under three different intensity levels (dark, weak, strong) of infrared beam illumination on ZnSe cathode electrode, were measured by using a phomultiplier tube that is sensitive to UV–Visible wavelengths. In the numerical analysis section, simulation studies were carried out on the two-dimensional gas discharge-semiconductor microplasma system (GDSµPS) cell models using the finite-element method (FEM) solver COMSOL Multiphysics DC plasma program. Calculations and predictions were based on mixture-averaged diffusion drift theory and Maxwellian electron energy distribution function. GDSµPS cell was modeled in a square chamber with planar anode/cathode electrode pair coupled at a 50 μm discharge gap. Single side of ZnSe cathode was finely micro-digitated to increase the effective surface area for enhanced electron emission to the gas discharge cell. The electrical equivalent circuit (EEC) of the proposed model was driven by 1.0 kV DC voltage source. Binary Ar/H2 gas medium in a mixture of 3:2 molar ratio was introduced to the gas discharge chamber at constant 200 Torr subatmospheric pressure. Simulations were run for normal glow discharges to exhibit the electrical fast transient glow discharge behaviours from electron field emission state to self-sustained normal glow discharge state by numerically solving the electron density (ED), electron current density (ECD) and electric potential distribution (EPD) parameters.It is figured out that binary Ar/H2 gas discharge model can undertake a major role in shaping and controlling the spatiotemporal response to transient electro-optical behavior of microplasma-based artificial electromagnetic materials configured for high-efficiency infrared-to-visible wavelength conversion applications.

Anomalous Adsorption of PFAS at the Thin‐Water‐Film Air‐Water Interface in Water‐Unsaturated Porous Media

AbstractPer‐ and poly‐fluoroalkyl substances (PFAS) are interfacially‐active contaminants that adsorb at air‐water interfaces (AWIs). Water‐unsaturated soils have abundant AWIs, which generally consist of two types: one is associated with the pendular rings of water between soil grains (i.e., bulk AWI) and the other arises from the thin water films covering the soil grains. To date, the two types of AWIs have been treated the same when modeling PFAS retention in vadose zones. However, the presence of electrical double layers of soil grain surfaces and the subsequently modified chemical potential of PFAS at the AWI may significantly change the PFAS adsorption at the thin‐water‐film AWI relative to that at the bulk AWI. Given that thin water films contribute to over 90% of AWIs in the vadose zone under many field‐relevant wetting conditions, it is critical to quantify the potential anomalous adsorption of PFAS at the thin‐water‐film AWI. We develop a thermodynamic‐based mathematical model to quantify this anomalous adsorption. The model couples the chemical equilibrium of PFAS with the Poisson‐Boltzmann equation that governs the distribution of electrical potential in a thin water film. Our model analyses suggest that PFAS adsorption at thin‐water‐film AWI can deviate significantly (up to 82%) from that at bulk AWIs. The deviation increases for lower porewater ionic strength, thinner water film, and higher soil grain surface charge. These results highlight the importance of accounting for the anomalous adsorption of PFAS at the thin‐water‐film AWI when modeling PFAS fate and transport in the vadose zone.

Effects of joule heating and viscous dissipation on electromagneto-hydrodynamic flow in a microchannel with electroosmotic effect: Enhancement of MEMS cooling

This paper inspects the effect of Joule heating and viscous dissipation due to electric double layer (EDL) and electroosmotic effect on steady fully developed electromagnetohydrodynamic flow in a microchannel. Dimensionless formulations of the Poisson-Boltzmann, momentum, and energy equations are derived for the electric potential, velocity profile, and temperature distribution in the microchannel. Exact solutions for the temperature distributions and velocity profile were obtained using the method of undetermined coefficients. The Debye-Hückel linearization is used to get exact solution for the electric potential. The results showed that Brinkmann number [Formula: see text], Joule heating parameter [Formula: see text], Debye-Hückel parameter [Formula: see text], Hartmann number [Formula: see text], and electric field [Formula: see text] have a substantial impact on flow formation and heat transfer. The complex interaction between joule heating, viscous dissipation, and the EOF effect were accurately captured. The range values for the governing parameter for [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], and [Formula: see text] are [Formula: see text], and[Formula: see text] respectively.

Modelling EEG Dynamics with Brain Sources

An electroencephalogram (EEG), recorded on the surface of the scalp, serves to characterize the distribution of electric potential during brain activity. This method finds extensive application in investigating brain functioning and diagnosing various diseases. Event-related potential (ERP) is employed to delineate visual, motor, and other activities through cross-trial averages. Despite its utility, interpreting the spatiotemporal dynamics in EEG data poses challenges, as they are inherently subject-specific and highly variable, particularly at the level of individual trials. Conventionally associated with oscillating brain sources, these dynamics raise questions regarding how these oscillations give rise to the observed dynamical regimes on the brain surface. In this study, we propose a model for spatiotemporal dynamics in EEG data using the Poisson equation, with the right-hand side corresponding to the oscillating brain sources. Through our analysis, we identify primary dynamical regimes based on factors such as the number of sources, their frequencies, and phases. Our numerical simulations, conducted in both 2D and 3D, revealed the presence of standing waves, rotating patterns, and symmetric regimes, mirroring observations in EEG data recorded during picture naming experiments. Notably, moving waves, indicative of spatial displacement in the potential distribution, manifested in the vicinity of brain sources, as was evident in both the simulations and experimental data. In summary, our findings support the conclusion that the brain source model aptly describes the spatiotemporal dynamics observed in EEG data.

WITHDRAWN: Design of partial discharge measurement model for internal cavities in high voltage power cables

The phenomenon of partial discharge (PD) in power cables can result in insulation degradation and eventual failure if left undetected and unaddressed. As a result, the measurement of PD is key to evaluating the performance of insulation diagnostics in the power cables. This paper presents a PD measurement model for internal cavities in XLPE insulating material for medium voltage power cables. The proposed PD measurement model is designed using the COMSOL Multiphysics software as a finite element analysis (FEA) tool added to MATLAB environment, specifically tailored for power cables. The proposed PD measurement model uses the multiphysics capabilities of COMSOL to simulate the electrical discharges behavior within power cables. The model considers factors such as cable geometry, material properties, cavity size, applied voltage and numerical conditions to accurately capture the PD characteristics. Distributions of both electric potential and electric field were studied before and after occurrence of PD across the internal cavity. According to the results, it has been noticed that the discharge magnitude mainly depends on the cavity diameter; as increasing cavity diameter leads to increasing the magnitude of the measured PD. Moreover, the leakage current magnitude is recorded during the PD event period. The proposed model also enables the evaluation of different cable designs, insulation materials, and operating conditions to optimize cable performance and mitigate PD risks.

Investigation on Ion extraction processes in M-Type electrode configuration and the influence of top electrode

In the realm of ion extraction from photoplasma, the design of electrode configuration exerts a significant influence over-extraction efficiency by tailoring the vacuum gap and electric potential distribution. Over time, various electrode configurations have been explored, including parallel-plate, wire-type, M-type, and Π-type designs. Notably, the M-type configuration has shorter ion extraction times. In the present study, a comprehensive investigation of the ion extraction process with the M-Type setup is performed using a 2D2v-electrostatic Particle-in-Cell simulation. The study focuses on the spatiotemporal evolution of photoplasma, the formation of the plasma sheath, and the spatial distribution of electric potential. Subsequently, a series of computational experiments have been conducted by systematically altering the size of the top electrode in the M-type configuration, effectively transforming it into wire-type and Π-type. The objective of these experiments is to explore the impact of the top electrode on ion extraction. The obtained simulation results report a significant finding: the formation of a virtual anode between the cathodes. This distinct phenomenon substantially contributes to an exceptional level of efficiency, exceeding 90%, among different simulated configurations. Furthermore, it also reports an approximate 95% collection efficiency with minimum collection time with an M-type configuration over the Π-type electrode configuration.

Bionic vine-stems structure for enhancing electrochromic cyclic stability and mechanical stability of multiband spectral regulation fiber

Wearable electrochromic (EC) devices can adjust visible-infrared spectra demonstrate promising potential for applications in display, decoration, personal thermal management, and adaptive thermal camouflage. However, existing flat layer-layer EC devices are hindered by poor air permeability, limited flexibility, and integration difficulties with fabrics, particularly in the realm of intelligent wearables. The creation of highly efficient fiber-shaped infrared (IR) modulation devices with exceptional structural and performance stability represents a significant challenge. We draw inspiration from the arboreous vine-stems structure observed in Chinese wistaria, which effectively minimizes the risk of damage to their vine and stems during harsh weather conditions. We have successfully designed a wearable high efficient multiband spectral regulation fiber (MSRF) with a bioinspired vine-stems structure using carbon fiber and polyaniline (PANI) as the active layer. The planar working electrode (Au) with PANI deposited on its surface was spirally wound around the counter electrode (carbon fiber) and separated by a gel electrolyte (PC/LiClO4), with polyolefin serving as the encapsulation layer. The distribution of electrical potential and lithium ions in the MSRF were analyzed using finite element analysis, demonstrating exceptional electrochromic stability without the length limit of the fiber. Moreover, the MSRF exhibited exceptional IR emissivity (△ε = 0.528) within the 8–14 μm range, fast response time (2.44 s) at low applied potentials (−0.8 V and 0.8 V), robust long-term cycling stability (at least 5000 cycles), and remarkable mechanical stability (at least 5000 bending cycles). The compatibility of the fiber with fabric and potential for patterning using MSRF with high length was also explored, providing new insights into the development of wearable adaptive thermal camouflage and spectral regulation fiber devices.

Unraveling the electrical energy loss in silver nanowire electrodes for flexible and Large-Area organic solar cells

Although the transparency and sheet resistance of silver nanowire (AgNW) electrodes are comparable to those of rigid indium-tin-oxide electrodes, flexible organic solar cells (FOSCs) are still less efficient than their rigid counterparts. Herein, by recording the microscopic photocurrent images of AgNW-based FOSCs in operation, it has been revealed that the limited lateral charge collection range of AgNW leads to inevitable electrical energy loss. The regulation of carrier mobility and energy level of adjacent ZnO electron transport layer increases the effective collection range of AgNWs by 1.8 times and uniform the electrical potential distribution in FOSCs. The D18:Y6:PC71BM-based FOSCs achieve a power conversion efficiency of approaching 18%. Moreover, the performance drop of large-area FOSCs is significantly reduced due to the improved charge collection on large area scale. This work provides an intuitive insight into the electrical energy loss mechanism of AgNW electrodes and demonstrates an electric field regulation strategy in FOSCs.

Numerical solution of differential games with electric potential distributions in some domain

Numerical solution of differential games with electric potential distributions in some domain

Rayleigh analysis and numerical simulations of metal-mesh/ transparent conducting oxide composite transparent electrode

Transparent conducting oxides (TCOs), especially indium tin oxides (ITOs), have played an important role in realizing optoelectronics devices. Composite electrodes fabricated by introducing different types of metal-meshes into TCO have exhibited improved electric properties as well as good transparency. This technology can also reduce the demand for ITO and provide the candidates of flexible electrodes for wearable devices. Analysis of the electric properties of this type of electrode, such as the variance of the sheet resistance of the composite electrodes with the embedded mesh structure parameters, can provide a theoretical basis for designing and fabricating this electrode. But detailed studies are still lacking. This work focuses on the electrical property analysis of the typical square hole and grid shaped metal mesh-TCO composite electrodes based on Rayleigh model and finite-element simulation, respectively. The electric potential distribution and current density distribution are obtained from the finite element calculations, revealing that the dramatic deformation of the metallic channels in the composite results in the failure of a conventional Rayleigh model for the moderate and high opening rates. Accordingly, we adopt a lattice correction to the Rayleigh model to reduce the channel deformation by increasing the symmetry of the exterior boundary of the lattice cell. A comparison of the results from the simulations with those from the second-order approximation of the lattice-adapted Rayleigh model shows that the new analytic form of the effective conductivity is applicable to a much larger opening-rate range for both the monolayer and the sandwich structures of metal-mesh TCO composite electrodes. The variances of the sheet resistance and the effective conductivity with different material and structure parameters of the composite electrodes are calculated and discussed based on the lattice-adapted Rayleigh approximation. The results are well consistent with experimental results. A comparison of our model with other theoretical models is also made, showing that this lattice-adapted Rayleigh approximation can be used as a simple and efficient theoretical tool to analyze and design the concerned transparent composite electrodes.

Graphene & its applications as field effect transistors

Graphene, owing to its excellent physical, mechanical, and electrical properties, as well as its outstanding optoelectronic properties, has garnered significant attention. Consequently, it has opened numerous opportunities for various types of future devices and systems. Graphene, a one-atom-thick layer of carbon atoms forming a honeycomb 2D crystal lattice, stands out as one of the most promising candidates in the field of nano- and microelectronics. This review provides an introduction to graphene, detailing its properties and its applications, particularly focusing on its utilization in the realm of Field Effect Transistors (FETs). Specifically, an analytical device model of heterostructure-based FETs is presented, which essentially comprises an array of nano ribbons clad. The model for Graphene Nano Ribbon (GNR) FETs includes Poisson's equation and can be employed to calculate the current-voltage characteristics and spatial distribution of electric potential along the channel.

Thermomagnetoelectric convective effect in normal and superfluid systems

Thermomagnetoelectric effect for the dielectric hydrodynamic system is considered. It is established that in a liquid, which is placed in a magnetic field, the temperature gradient can cause a convective mass flow, which leads to the appearance of an electric field in the surrounding space. The distribution of electric potential for various geometric implementations is calculated. A comparison of the obtained effect for normal and superfluid 4He is performed.

Simulation Study of Critical Aspects of MIAB Welding for Analysis of Potential Factors Governing the Performance of Weld Formation

Magnetically Impelled Arc Butt (MIAB) welding, is a solid-state welding technique. The magnetic system of this technique is pivotal for the generation of the Lorentz force, which impels an arc to rotate along the periphery of the weld tubes and thus facilitates the heating of faying surfaces. The magnetic arrangement and the arc dynamics significantly impact the effectiveness of the welding process, eventually dictating the efficiency. This study case investigates the impact of the magnetic arrangement on the arc rotation and possible factors that cause irregularities in the (MIAB) welding through COMSOL simulation. The COMSOL simulation has served as a powerful tool to comprehensively analyse various arc dynamics and magnetic systems and extrapolate the observations to analyse the arc dynamics and magnetic systems involved in MIAB welding. By employing simulation studies, the research aims to unravel critical insights for an efficient design of the MIAB welding system. This work includes a study of the effect of magnetic forces on arc dynamics using various models and attempts to develop an analogy to the MIAB welding process. This is further utilized to explain the process variations in the form of arc displacement, electric potential distribution, and the possibility of self-demagnetization of AlNiCo magnets. Thus, it provides a foundation for advancing the technological aspects of MIAB welding to overcome the limitations and irregularities. This research is instrumental in enhancing the understanding of magnetic interactions involved in the MIAB process, which can further pave the way for improved welding machine designs and consequently, enable research on these lines that can help in establishing an optimized parametric window.

The Hemispheric Difference in Electric Potential and Electron Precipitation Observed by DMSP in the Auroral Zone

AbstractIn this case study, we focus on how hemispheric differences in the electric potential distribution in the auroral zones are related to hemispheric differences in the energetic particle precipitation that indicate the presence of field‐aligned potential drops. Utilizing data during the spring and fall equinox in 2013 and 2014 from the Defense Meteorological Satellite Program (DMSP) F16 and F17 satellites, we systematically examine simultaneous measurements of plasma drift velocity and particle precipitation in magnetically conjugate regions across the auroral zone in both hemispheres. This allows us to establish the degree to which the interhemispheric differences in ionospheric electric potential may be accounted for by field‐aligned potential drops. Thirty‐seven eligible cases examined show accelerated electron energy spectra at conjugate locations in the northern and/or southern hemispheres. Of these 37 cases, 23 show conjugate differences in electric potential that agree qualitatively with the observed electron acceleration and average energy of precipitating electrons in each hemisphere. This result suggests that the hemispheric differences in ionospheric electric potential in the auroral zone may be most frequently accounted for by field‐aligned potential drops along the magnetic flux tubes connecting conjugate points to the equatorial plane. The spatial and temporal variability of the potential distribution, electron precipitation, and magnetic field configuration could account for deviations from the normally observed situation in the remaining cases. More magnetically conjugate observations at various altitudes in both hemispheres are needed to investigate this hemispheric coupling in more detail.

ON THE METHOD OF SIMULATING A CRACK FILLER BETWEEN TWO PIEZOELECTRIC MATERIALS

A calculation model that takes into account the dielectric permeability of the crack medium is suggested for a crack at the interface of two piezoelectric materials. This model was analyzed by using the finite element method. The graphs of electric flux, displacement jumps, and electric potential distributions along the crack faces are obtained.