Increase In Electric Potential Research Articles

Study on electric erosion in grease lubrication using optical interference method

Protecting bearings from electrical environments is crucial as modern industry evolves. With increasing exposure to electrical conditions, the risk of bearing failure due to electric erosion becomes a significant concern. To better understand how lubrication interacts with electric discharge in rolling bearings, an optical ball-on-disc tribometer was modified to measure film thickness under elastohydrodynamic lubrication (EHL) with electric discharge. The results of the study revealed that an electrical potential difference between the surfaces separated by the lubrication film leads to a reduction in film thickness, which can be attributed to the generation of Joule heating. As the electrical potential difference increases, the film thickness decreases even further, ultimately resulting in destructive electric discharge. Interestingly, sporadic discharge was observed in the region of minimum film thickness as the entrainment velocities increased prior to the occurrence of destructive discharge. In addition, the study also investigated the use of grease with a conductive additive, a double trifluoro-sulfonate ionic liquid. It was found that incorporating this ionic liquid into the grease can decrease the energy during discharge, thereby mitigating bearing electric erosion.

Nitrogen compounds removal from brackish water by electrodialysis at fixed electric potential and dynamic current density operations

Nitrogen (N) compounds can occur in water resources from natural and anthropogenic activities. It is ideal that these contaminants be removed before water consumption. As water quality has been affected by increased salinity and pH variation, more advanced and robust technologies such as electrodialysis (ED) can be considered for simultaneous desalination and pollutant removal. In this context, the removal of N-species (NO3−, NO2−, NH4+, and CH4N2O) from brackish water by ED was investigated for different feed water quality, considering increased salinity (0 – 10g/L NaCl) and pH variation (3 – 11), under limit current density (LCD) at fixed electric potential condition. The applied electric potential (5 – 25V) under, at, and over the LCD at fixed electric potential and dynamic current density (DCD), as a percentage of LCD (0.4 - 1.2), were analyzed to improve the process. In addition, energy efficiency in the form of specific energy consumption (SEC) and current efficiency (CE) were assessed for ED at fixed electric potential and DCD. The results showed that, at extreme pH of the feed water, the removal of NO2− and NH4+ can be affected, while NO3−was the most stable compound with pH variation. An increase in feed water salinity just slightly impacted the removal of N-compounds, due to the similar characteristics of the ions in the water. The increase in electric potential at fixed electric potential or DCD increased the removal and molar flux of N-compounds. However, operating over the LCD increased the SEC of the ED process while changes in removal were not significant. DCD procedures resulted in higher CE and shorter run time of the experiments. Therefore, ED proved to be a suitable treatment technique to produce fresh water due to the selective removal of the studied ions, especially at 15V (fixed electrical potential) and 0.8 LCD (DCD) related to removal, molar flux, and run time to achieve guidelines.

Effect of electric potential on the structure and yield of graphene oxide using electrochemical exfoliation method

Optimization of the electrochemical exfoliation of graphene oxide synthesis was investigated in this report using varying potentials. Graphite from waste lithium-ion batteries was used as the electrodes for the DC (direct current) electrochemical set-up. Electric potentials of 7.5 V, 12 V, and 15 V were applied for 225 minutes using 0.2M H2SO4 as the electrolyte. The characterization of the produced graphene oxide was done using Raman spectroscopy, high-resolution scanning electron microscopy (HRSEM), and energy dispersive x-ray spectroscopy (EDS) attached to the scanning electron microscope (SEM). The results obtained showed that both the rate of graphene oxide yield and the C/O ratio increased correspondingly with the increase in electric potential. However, the structure of graphene oxide produced at 7.5 V was of superior quality compared to others produced at higher potentials with regards to the crystallite lattice characteristics such as defects, lateral dimensions, thickness, and the number of graphene layers. Consequently, tailor-made graphene oxide properties (and yield) for target applications may be achieved using the electrochemical exfoliation method via the choice of the electric potential.

Gas puff imaging measurements during resonant magnetic perturbations on the HL-2A tokamak

The gas puff imaging diagnostic is used for the investigation of the poloidal flow and turbulent fluctuations at the plasma edge and scrape-off layer (SOL) on the HL-2A tokamak. The impact of resonant magnetic perturbations (RMPs) on the edge poloidal velocity () are investigated and compared during the operation of a stair-like rising RMP coil current (). The application of the RMP is observed to modify the poloidal velocity significantly. When exceeds 4 kA, the turbulence poloidal velocity at the edge changes direction from electron to ion diamagnetic drift. This phenomenon is explained by the electron loss along the perturbed radial magnetic field with RMP, with the experimental evidence provided that the edge electric potential increases significantly. A strong impact of the RMP on the properties of plasma density fluctuations in the SOL is also observed. With RMP, both skewness and kurtosis are smaller in the SOL and large-scale turbulence structures (small and ) are suppressed in both edge and SOL. These results can improve our understanding of the interaction between RMP and edge turbulence and in particular, the edge poloidal flow.

Theoretical analysis on electrohydrodynamic instability of a low viscous electrified jet

In present work, a dispersion equation describing electrohydrodynamic (EHD) instability of a low viscous electrified jet was derived, where the Naiver-Stokes equations combined with the electrodynamic and hydrodynamic boundary conditions are utilized. The effect of operating parameters containing electric potential, initial jet velocity and electrode spacing on stability of the electrified jet was systematically examined and extensively analyzed, as well as liquid properties including liquid viscosity and surface tension. The analysis indicate that the axisymmetric surface waves dominate the breakup instability of the electrified jet at low electric potential or low flowrate. As flowrate or electric potential increases, the influence of the non-axisymmetric surface waves is gradually enhanced. The electrode spacing and initial diameter of the jet also have extremely slight effect on the surface wave growth rate. The viscosity could stabilize the electrified jet and almost has no influence on the maximum wave number. With the surface tension increasing, the stability of the jet is usually enhanced. The analytical results agree well with the experimental observation in the varicose instability. Meanwhile, the discrepancy between the predicted and experimental data in the whipping instability indicates the influence of non-linear perturbations is indispensable.

Exact closed-form solutions for behavior investigation of heterogeneous piezo-magneto-elastic discs under magneto-electro-hygro-thermo-mechanical loads

The purpose of this study is to propose full-analytical closed-form solutions for functionally graded magneto-electro-hygro-thermo-elastic (FG-MEHTE) discs exposed to various combinations of the magneto-electro-hygro-thermo-mechanical loads. The formulations account for the elastic, piezoelectric, dielectric, magnetic, piezomagnetic, pyroelectric, pyromagnetic, and hygrothermal properties of the disc. Different exponential through-thickness variations are adopted for distinct material properties. General hygrothermal boundary conditions are taken into consideration and the distributions of the rises in the moisture concentration and temperature are determined according to Fick and Fourier equations, respectively. Based on the constitutive equations of the axisymmetric hygro-thermo-elasticity problem, the Navier equations are derived. The series solutions that are proposed for the displacement field and the electric and magnetic potentials consist of appropriate superpositions of exponential and Bessel functions whose arguments are ascertained based on the edge conditions. The boundary conditions of the top and bottom faces of the disc are employed to determine the unknown coefficients of the mentioned series solutions. Results reveal that by increasing the volume fraction of the piezoelectric phase, the electric potential increases but the magnetic induction and the magnetic potential decrease in such a way that the resulting distributions of the axial and radial magnetic inductions become respectively, similar to those of the transverse normal and transverse shear stresses. In contrast to the reductions in the displacements and stresses, the magnitude of the transverse shear stress and electric and magnetic potentials grow with the thickness.

Energy harvesting using PZT4 based beam type structural element

Piezoelectric materials are mainly used for the development of sensors and actuators. However, they are also used to develop structures to harvest electricity. This study uses the most utilized piezoelectric material, lead zirconate titanate (PZT4), as a structural element. The structural element is modeled in the form of a rectangular beam. The material properties of PZT4 such as dielectric constant, elastic orthotropic, piezoelectric, and density are used to model the rectangular beam. To analyze the piezoelectric effect, the potential difference at the bottom surface of the beam is kept at zero. Then, the compressive load, or pressure, is applied at the top and bottom surfaces of the beam. As a result of finite element analysis, it is observed that the electric potential increases with the increasing load. A maximum electric potential of 977 V is obtained under 20 kPa of compressive load. The results of this study can be used as a basis for the development of energy harvesting devices based on piezoelectric materials. In the future, FEA can be used to analyze the inverse piezoelectric effect for the development of actuators.

Diurnal Variations in Vegetation Activity affecting Shallow Groundwater Flow identified by Microthermal Measurements

Observations of summer microthermal temperature variations suggest, next to hydrological factors, a significant influence of plant activity on groundwater flow in fractured claystone materials. Variations in groundwater microtemperature were compared to variations in meteorological parameters and electrical potential of plants. With an increase in surface temperature, relative air humidity decreases and an increase in tree electrical potential, measured as the difference between the northern and the southern stem exposure (N–S), can be observed. This increase in electrical potential is concomitant with a change in groundwater temperature of approximately 2 mK. This relationship does not always occur. At high temperatures (+30°C) the decrease amounts to just 1 mK. This fact is related to the change in transpiration of plants, decreased or even suspended at high surface temperatures. A frequency analysis of all data showed a daily frequency of high magnitude in all parameters. Possibly changes in the macro weather situation events were observed in the results of atmospheric pressure, southern electric potential and groundwater temperature. The lag time between changes in electric potential and subsurface microtemperature changes amounts to 17 hours, possibly a result of the electrical potential difference between the northern and the southern exposure of the stem (N–S), and 5 hours, the result of the change in electrical potential difference between the southern and the northern stem exposure side (S–N). A comparison between potential changes and the computed change in gravity resulting from earth tidal effects showed that the correlation between the subsurface temperature variation with up to 2 mK and the change in surface temperature variation does not match directly. Other study shows that the impact of earth tides on subsurface microtemperature variation amounts to ca. 1mK. The effect of groundwater abstraction by mature vegetation is determined at the same range. Atmospheric tides can be correlated with the changes in north and south electric potentials.

On the cone-to-jet transition region and its significance in electrospray propulsion

A novel method for identifying the cone-to-jet transition region is proposed to characterize the electrospray dynamics, and thus the Taylor cone, a fundamental principle of ion extraction from the tip of the Taylor cone in an electric field to produce μN thrust for nanosatellites' application. A numerical model is developed and validated against the droplet's diameter with a proper characterization of the cone-to-jet transition region based on the hydrodynamic pressure gradient at the cone-jet axis. The results show that the cone-to-jet transition region is reduced when the electric potential increases and the flow rate decreases. Moreover, the current density is found to be higher for the lower flow rate and large electric potential. Interestingly, the current density at the jet axis increases significantly at the flow rate of 1 cc/hr. This implies that below a certain droplet diameter, the current density carried by the jet interface is completely migrated into the jet, and the substantial change in the current density occurs within the cone-to-jet transition region. When comparing the current density along the jet axis, the small flow rate and large electric potential carry the maximum current density at the jet interface. The identification of cone-to-jet transition region is central in modeling the ion beam trajectory via initial current density profile required for particle-in-cell calculation for assuring the performance of a field emission electric propulsion thruster.

Electrohydrodynamic instability and disintegration of low viscous liquid jet

The simple-jet mode can be developed from dripping, dripping faucet (transition), and jetting when subjected to a sufficient strong electric field caused by a needle-plated electrode. In the present work, the instability and disintegration of an electrified jet of anhydrous ethanol in the electrohydrodynamic simple-jet mode are visualized by a high-speed camera. A systematic analysis and description on the evolution of the breakup morphology of the charged jet in the simple-jet mode was carried out. In the dripping mode at low Weber number, the unstable simple-jet occurs, while the stable simple-jet mode happens as Weber number higher than critical value. In a dripping faucet and jetting regime, the simple-jet mode can easily take place, and jet undergoes typical breakup modes including varicose, whipping, whipping assisted bifurcation, and ramified instabilities as electric potential increases. The growth rate of the maximum perturbation of the zero-, first-, and second-order surface waves determines the type of the instabilities. The operating window of the simple-jet mode is presented to indicate that the simple-jet mode only operates in the suitable range of Weber number and electric Bond number. The spray characteristics, including envelope angle, droplet size, and the stable length of the electrified jet, have been explored to demonstrate that the uniform drops could be generated in the simple-jet regime. The evolution from the cone-jet to the simple-jet mode is also observed when a special hemispherical nozzle is used. For an almost stable electric potential, the cone-jet can gradually transform into the simple-jet with an increase in the liquid flow rate.

Study of the Neon Dielectric Barrier Discharge on a Capacitively Coupled Radio Frequency at a Low Pressure with Metastable Atom Density: Effect of the Pressure

We study the neon dielectric barrier discharge with metastable atom density on a capacitively coupled radio frequency at a pressure of about 4–12 Torr. The transport parameters of neon are dependent on the electron energy, and their range is about 0.04–50 eV. A one-dimensional fluid model and the drift-diffusion theory are used to describe the neon dielectric barrier discharge. The effect of the gas pressure on the properties of neon dielectric barrier discharge is presented for the cycle-averaged regime. It is shown that the particle densities, electric potential, and metastable atom density increase with the pressure. In addition, the surface charge concentration and the gap voltage increase as well.

Sulfur dioxide absorption by charged droplets in electrohydrodynamic atomization

This work presents and discusses the absorption of sulfur dioxide by charged calcium hydroxide aqueous solution droplets generated in electrohydrodynamic atomization (EHDA). The removal of sulfur dioxide is experimentally tested in a laboratory scale device, and the main factors affecting the absorption of sulfur dioxide, droplets diameter and specific charge, are obtained. The results indicated that the liquid-gas contacting interface area significantly increaes because droplets diameter decreases with an increase in electric potential. The specific charge increases as electric potential increasing, may lead to the uniform distribution of charged droplets in the spraying tower. The analysis of these findings indicated that the absorption rate and enhancement factor are improved in EHDA. The absorption efficiency can be significantly increased mainly because of the increase of contacting area between gas and liquid due to the disintegration of liquid in EHDA, and the uniform distribution of electrified droplets in the tower due to repulsive forces. Meanwhile, the activity of calcium ions can be improved due to electric field and charges on the droplets surface. There are also some interactions between the gas molecules near the droplet and the liquid molecules in electric field, which is difficult to characterize. In addition, the internal circulation induced by electric and flow fields inside the droplets may also enhance soluble gaseous pollutants transport.

Static analysis of porous core functionally graded piezoelectric (PCFGP) sandwich plate resting on the Winkler/Pasternak/Kerr foundation under thermo-electric effect

This paper analyzed static bending and deflection of the porous core functionally graded piezoelectric (PCFGP) sandwich plate resting on the Winkler/Pasternak/ Kerr foundations under thermomechanical and electromechanical loading with different conventional and unconventional boundary conditions. First-order shear deformation theory (FSDT) based displacement field and von Karman geometric nonlinear strain are used for problem formulation. The governing equations of the PCFGP sandwich plate are obtained using Hamilton’s principle. A higher-order finite element method has been employed with a modified iterative Newton-Raphson scheme for solving the governing equations. Convergence and comparison studies demonstrate that the validation of the current model has suitably correct. It has been observed that an increase in the porous exponent in the core part of the sandwich plate reduces the stiffness of the plate with an increase in stress, deflection, and electric potential. The maximum stress, deflection, and electric potential are obtained for porosity dispersion in the Uniform pore distribution (UD) type, while minimum in Un-symmetric pore distribution (USD) type dispersions. Hence, the different embedding porosity in the core part of the sandwich plate plays a significant role in reducing plate structural weight and offering good stability in plate structural bending stiffness.

Organoplatinum Compounds as Anion‐Tuneable Uphill Hydroxide Transporters

AbstractActive transport of ions uphill, creating a concentration gradient across a cell membrane, is essential for life. It remains a significant challenge to develop synthetic systems that allow active uphill transport. Here, a transport process fuelled by organometallic compounds is reported that creates a pH gradient. The hydrolysis reaction of PtII complexes results in the formation of aqua complexes that established rapid transmembrane movement (“flip‐flop”) of neutral Pt−OH species, leading to protonation of the OH group in the inner leaflet, generating OH− ions, and so increasing the pH in the intravesicular solution. The organoplatinum complex effectively transports bound hydroxide ions across the membrane in a neutral complex. The initial net flow of the PtII complex into the vesicles generates a positive electric potential that can further drive uphill transport because the electric potential is opposed to the chemical potential of OH−. The OH− ions equilibrate with this transmembrane electric potential but cannot remove it due to the relatively low permeability of the charged species. As a result, effective hydroxide transport against its concentration gradient can be achieved, and multiple additions can continuously drive the generation of OH− against its concentration gradient up to ΔpH>2. Moreover, the external addition of different anions can control the generation of OH− depending on their anion binding affinity. When anions displayed very high binding affinities towards PtII compounds, such as halides, the external anions could dissipate the pH gradient. In contrast, a further pH increase was observed for weak binding anions, such as sulfate, due to the increase of positive electric potential.

In Situ Monitoring of Transmetallation in Electric Potential-Promoted Oxidative Coupling in a Single-Molecule Junction

In Situ Monitoring of Transmetallation in Electric Potential-Promoted Oxidative Coupling in a Single-Molecule Junction

Relationship between emotional state and masticatory system function in a group of healthy volunteers aged 18-21

ABSTRACT Objective To determine the role of emotional state in the masticatory system function in a group of young adults. Methods Ninety-six generally healthy randomly selected students aged 18–21 were examined. They were subjected to a questionnaire survey determining their emotional state, clinical examination, and instrumental diagnostics (EMG, Cadiax Compact, JVA). Results The stress symptoms group revealed a greater intensity of neck and shoulder muscles pain (p < 0.05) and an increase of electrical potential of the masseter muscles in maximal voluntary clench (p < 0.05). They reported more often headache (p < 0.001), tension/contracture of the head, neck and nape (p < 0.05), and pain while opening the mouth wide (p < 0.05). The values of parameters obtained in the instrumental diagnostics did not reveal differences between the groups. Conclusion Stressful situations increase muscular tension but do not have a direct impact on the temporomandibular joints function.

Exploring the potential application of hybrid permonosulfate/reactive electrochemical ceramic membrane on treating humic acid-dominant wastewater

Discharge of untreated or improperly managed landfill leachate could pose a significant threat on environment due to the high strength of complex inorganic composition and abundant refractory humic acid (HA). This is the first work introducing a promising energy efficient technology using Ti4O7 anode reactive electrochemical membrane (REM) coupled with permonosulfate (PMS) to address HA-enriched wastewater. The removal performance, possible generation of reactive species along with reaction mechanisms in PMS/REM system were proposed and compared with the traditional REM system. Regardless of electrical potential, chlorine concentration, water flux and PMS dosage (with similar ionic strength by adding SO42- for REM alone), the hybrid PMS/REM system prevails the REM system alone in terms of HA degradation and energy efficiency. However, the extent of removal performance is also largely dependent upon specific condition. An increase in PMS dosage and anode electrical potential was beneficial for HA degradation, but addition of chloride imposed adverse effects on HA removal efficiency. Of those parameters, the influence of water flux on HA degradation was trivial. Compared to REM alone, in which HA was mostly removed via electrosorption, PMS/REM system, otherwise, significantly enhanced mineralization of HA. The electron paramagnetic resonance experiments demonstrated the absence of sulfate radical (SO4•-) in the PMS/REM system and implied that the more efficient performance of the hybrid system over the REM system was likely ascribed to the higher yield of hydroxyl radical (•OH). Besides, nonradical oxidation also played an important role in the PMS/REM system with the formation of a transition state of PMS molecule (PMS*), which could facilitate •OH production by inhibiting oxygen evolution site reactions.

Dynamics of electrified jets in electrohydrodynamic atomization

An electrified jet ejected from a meniscus (or Taylor cone) can further disintegrate into fine drops with different modes in electrohydrodynamic atomization (EHDA). This process has been applied into many fields because of controllable production of highly charged and monodispersed drops. However, both stable and unstable electrified jets are encountered in EHDA, usually depending on liquid physical properties and operating parameters. A series of electrified jets are visualized and the transient breakup dynamics are analyzed within an electric field. According to the geometry forms of drops or/and jets emitted from the end of a needle, periodic dripping, pulsating-jet, stable-jet, and unstable jet are clearly classified. The operating parameters versus spraying modes are also discussed, especially for propylene glycol and n-octanol. The initial velocity from the Taylor cone, jet breakup length, jet position, and the size separation effect are deeply studied. The jet velocity is significantly accelerated by electric stresses and good agreement with predicted value. The jet breakup length increases sharply as liquid flow rate increasing and slowly increases as electric potential increasing, except for small liquid flow rate where bullet cone occurs. The jet ejection point varies and gradually deflects off needle axis with an increase in electric potential. The ‘size separation effect’ can help improve the quality of printing by removed highly charged satellite drops.

Mechanical Analysis of the Quadruple Butterfly Coil during Transcranial Magnetic Stimulation and Magnetic Resonance Imaging.

Transcranial Magnetic Stimulation (TMS) is a tool for the treatment of psychiatric and neurological disorders. It involves using a transient magnetic field generated from electromagnetic coils in inducing an electric field (E-field) within the neurons of the brain. The induced E-field results in an increase in the brain membrane's electric potential, leading to polarization or depolarization of the neurons depending on the mode of treatment. There has been much development in TMS technology recently, with most research focusing on improving the performance of TMS coils at greater depths and achieving more localized stimulation. Another development has been the combination of TMS with other medical techniques such as Functional Magnetic Resonance Imaging (fMRI) and Electroencephalography (EEG) to enable accurate mapping of the brain's electrical activity during TMS. However, the TMS coils experience large forces in this new highly energized external magnetic field environment. Accurately determining the magnitude and location of the Lorentz force, torque, and stresses that the TMS coils experience in this environment becomes of utmost importance. In this chapter, the authors used finite element analysis to determine the magnitude and location of the Lorentz forces and stresses experienced by a novel TMS coil, Quadruple Butterfly Coil (QBC), in a TMS-fMRI operation. With the TMS-fMRI operation, the maximum values of the magnetic flux density, Lorentz force density, and von Mises stress were observed in the z-axis of the QBC orientation. They resulted in a 39.65 %, 38.94 %, and 94.59 % increase, respectively, from the typical TMS operation.

An Effect of Electrokinetics Phenomena on Nonlinear Wave Propagation in Bubbly Liquids

A study of nonlinear waves in liquid-gas mixtures with the consideration of internal effects is an important problem of both the fundamental and the applied fluid mechanics. Investigation of nonlinear waves in the gas-liquid mixtures with allowance for internal effects is an important task of both fundamental and applied fluid mechanics. These problems often arise in industrial processes such as oil and gas production, hydrocarbons pipeline transportation, gas-saturated fluids flow in pipelines, etc. In this work, we investigate the effect of the internal electric field on the nonlinear wave propagation in a bubbly liquid. Numerical simulations have been conducted to study the nonlinear waves described by the nonlinear Burgers-Korteweg-de Vries equation. The numerical simulations showed that the electrokinetic processes significantly affect the wave propagation process. The amplitude of the waves gradually decreases when the size of the gas bubble is decreasing and the electrical potential increases. A good agreement of obtained results with our previous predictions is found.