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A complete mathematical model for electromigration in paper-based analytical devices is derived, based on differential equations describing the motion of fluids by pressure sources and EOF, the transport of charged chemical species, and the electric potential distribution. The porous medium created by the cellulose fibers is considered like a network of tortuous capillaries and represented by macroscopic parameters following an effective medium approach. The equations are obtained starting from their open-channel counterparts, applying scaling laws and, where necessary, including additional terms. With this approach, effective parameters are derived, describing diffusion, mobility, and conductivity for porous media. While the foundations of these phenomena can be found in previous reports, here, all the contributions are analyzed systematically and provided in a comprehensive way. Moreover, a novel electrophoretically driven dispersive transport mechanism in porous materials is proposed. Results of the numerical implementation of the mathematical model are compared with experimental data, showing good agreement and supporting the validity of the proposed model. Finally, the model succeeds in simulating a challenging case of free-flow electrophoresis in paper, involving capillary flow and electrophoretic transport developed in a 2D geometry. Fil: Schaumburg, Federico. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; Argentina Fil: Kler, Pablo Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Centro de Investigaciones en Métodos Computacionales. Universidad Nacional del Litoral. Centro de Investigaciones en Métodos Computacionales; Argentina Fil: Berli, Claudio Luis Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; Argentina

Trap plays an important role in the charge transportation of three-layer oil-paper and the investigation of trap parameters at different degradation degree is of great significance for further research of the partial discharge (PD) mechanism. This article considers the turn-to-turn structure of on-board traction transformer. A defect model of three-layer oil-paper insulation was designed for PD test. The PD degradation samples are selected from the inception of PD to the breakdown of PD to study the characteristics of surface potential decay on degradation samples by using isothermal surface potential decay method. Given that, the trap distribution at different degradation stages was calculated and its influence on PD characteristics was investigated. The result shows that AC fluctuation voltages caused by inter-harmonic has a great influence on PD distribution, surface charge distribution and trap distribution. With the increase of degradation, the decay rate of surface potential increases and the decay rate of AC fluctuation voltages is larger than that pure AC. And also, the number of shallow trap with AC fluctuation voltages is larger than that with pure AC. The rate of free charge increases with the number of shallow trap increasing. More free electrons involves in the process of PD, accelerating the aging rate of three-layer oil paper samples. Therefore, it can be concluded that surface charge and trap distribution are helpful to clarify PD mechanism.

This paper presents an investigation of the underlying mechanism behind the interface charge barrier between oil and oil immersed paper. Two types of oils and two types of cellulose papers are selected in the study. The interface charges of the samples are measured by the pulsed electro-acoustic (PEA) method and the zeta potentials of different oil-paper combinations are also measured. The results show that the amount of interface charge changes with the type of oils and papers, and is much larger than the Maxwell-Wagner-Sillars (MWS) polarization charge. The difference in the amount of interface charges cannot be attributed to the difference in the conductivity and permittivity of the materials. It is suggested that the barrier for charge transport across the interface, which is formed due to the electric double layer, should be taken into consideration to explain the interface charge behavior in oil-paper insulation.

In power cables with sector current-carrying strands (SCSs), impregnated with paper insulation, there is a tangential electric field component along the layers. The permissible electric strength along the paper tapes is about ten times less than in the normal direction, which is taken into account when developing three-wire power cables impregnated with paper insulation for voltages of 20 and 35 kV. The use of modern paper—plastic-impregnated insulation having higher performance characteristics than conventional impregnated paper insulation, can promote the creation of more efficient cable designs with individually shielded sector-shape conductors in a common lead sheath for a voltage of 20 kV. Each insulated strand of such cables has a copper shield, and so it is enough to consider the electric field in the cross section of the insulation of one SCS. The electric potential distribution is described by the Laplace differential equation, the solution of which is implemented by the finite element method using the Ansys Maxwell software package. A numerical study of the electric fields has been carried out for power cables with SCSs that have a cross section of 400 mm2 for a voltage of 20 kV. The curvature radius of the cable sectors varied from 5 to 7 mm with an insulation thickness of 7 to 9 mm. Based on the research results, the maximum values of the normal and tangential electric field components depending on the curvature radius of the sector strand and insulation thickness have been obtained. Insulation areas have been allocated in which the maximum absolute values of the tangential electric field strength components have been observed. The allowable values of the sector curvature radius and the thickness of insulation for power cables with paper-impregnated insulation for 20 kV have been determined.

Paper Spray (PS) is an ambient ionisation technique that is conceptually simple, economical, direct and versatile. In its simplest form, the procedure for operation relies on the application of an electric potential to a triangular-shaped paper substrate with the addition of an extraction/spray solvent to generate charge droplets, without requiring any pneumatic assistance. Despite its promise and rapidly growing popularity, there are some practical challenges associated with PS implementation with scope to enhance its performance further. One such challenge relates to only a small fraction of the Taylor cone expansion being sampled at the MS inlet. In this work we propose a new arrangement for PS, which retains the inherent advantages of this popular technique without introducing additional variables, by using an ambient ion focusing lens that is held at the same potential as the paper substrate. A thorough investigation, consisting of visual spray inspection, electric field simulations and analytical evaluation, including analysis of paracetamol from saliva, shows that ambient ion focusing can provide up to a 50% improvement in spray stability, 60% increase in signal intensity and a 30% improvement in detection limits for routine paper spray mass spectrometry analysis.

Oil-paper insulation will inevitably endure impulse voltage with a superimposed dc voltage (superimposed voltage) because of introduced lightning or switching, which can induce charge accumulation and trigger flashover during the operation of a converter transformer. Temperature rise is also a nonnegligible factor that can significantly influence the performances of oil-paper insulation. This paper aims to reveal the effects of ambient temperature and superimposed voltage on surface charge and flashover behaviors in an oil-paper insulation system. Surface potential decay (SPD) experiments were performed under superimposed voltage with various polarity and amplitude combinations and at the temperature ranging from 20 °C to 80 °C. The results show that the initial surface potential and decay rate increase as the amplitude of the impulse voltage increases at 20 °C. The initial surface potential declines, and the process of SPD is accelerated at higher temperatures because of the increased concentration of shallow traps. Subsequently, flashover tests were conducted under superimposed voltage. It is found that flashover occurs after applying superimposed voltages even with a rather low dc voltage. In addition, the dc voltage component is primarily responsible for flashover. Weibull results also indicate that it is prone to trigger flashover at higher temperatures, because thermal excitation helps more carriers to escape from deep traps and participate in the process of flashover. Accordingly, the insulation characteristics of oil-paper system can be significantly influenced by superimposed voltage and temperature, which should draw great concern among the power grid.

In this work, for the first time, chromatographic paper was used for a multiphase extraction assisted by an electric field (MPEF) and directly coupled to paper spray mass spectrometry (PS-MS). Using this approach, five tricyclic antidepressants (TCAs) were determined in oral fluid. Firstly, the MPEF conditions were optimized using liquid chromatography-mass spectrometry (LC-MS/MS). The effects of the chromatographic paper and the types of electrolyte used in the acceptor phase, the organic solvent type and the amount used in the donor phase, the extraction time, and the applied electric potential were all investigated. After optimization, the analytes were extracted from the donor solution (sample and acetonitrile 1:1 (v/v)) over a period of 10 min at 300 V, crossing the free liquid membrane (1-octanol) and reaching the acceptor phase (chromatographic paper wetted with 400 mmol L−1 acetic acid). The method using LC-MS/MS was validated, demonstrating a linear range from 2 to 12 ng mL−1, with detection and quantification limits of 0.13–0.25 and 0.44–0.84 ng mL−1, respectively, an intraday precision of less than 20%, and no matrix effect observed. The optimized MPEF conditions were then applied to determine TCAs by PS-MS and for this analysis cyclobenzaprine was used as an internal standard. The easy, fast and direct approach of coupling MPEF with PS-MS analysis, as well as the pre-concentration and the low standard deviation of replicates (less than 20%), demonstrates that this method can be useful for screening in clinical and toxicological analysis.

An experiment studying the physical principles of electrophoresis in liquids was developed for an undergraduate laboratory. We have improved upon the standard agarose gel electrophoresis experimental regime with a straightforward and cost-effective procedure, in which drops of widely available black food coloring were separated by electric field into their dye components on strips of chromatography paper soaked in a baking soda/water solution. Terminal velocities of seven student-safe dyes were measured as a function of the electric potential applied along the strips. The molecular mobility was introduced and calculated by analyzing data for a single dye. Sources of systematic and random errors were investigated.

Purpose The purpose of this paper is numerical calculation of total electric field in oil-paper insulation. Now, there is no effective method to consider the influence of space charges when calculating the total electric field distribution in the main insulation system of the valve-side winding of an ultra-high-voltage direct current converter transformer. Design/methodology/approach To calculate the total electric field in an oil-paper insulation system, a new simulation method in single-layer oil-paper insulation based on the transient upstream finite element method (TUFEM) is proposed, in which the time variable is considered. The TUFEM is used to calculate the total electric field in an oil-paper insulation system by considering the move law of space charges. The simulation method is verified by comparing the simulation results to the test data. The move law of space charges and distribution characteristics of the electric field under difference voltage values in single-layer oil-paper insulation were presented. Findings The results show that the TUFEM has an excellent accuracy compared with the test data. When carrier mobility is a constant, the time to reach the steady state is inversely correlated with the initial electric field intensity, and the distortion rate of the internal total electric field is positively correlated with the initial electric field intensity. Originality/value This paper provides an exploratory research on the simulation of space charge transport phenomenon in oil-paper and has guiding significance to the design of oil-paper insulation.

The oil-impregnated paper in converter transformer, especially in valve side bushing, is suffered by the complicated electric field such as the composite electric field of AC and DC voltage or polarity reversal voltage. By reason of the power electronics and non-linear equipment, the oil-impregnated paper is also suffered by the harmonic voltage. In addition, the insulating aging is more prominent, which is attributed to the stray loss increasing caused by the DC magnetic bias. Then the degradation of cellulose chain occurs, which easily results in introducing new defects and forming the charge accumulation on the surface of oil-paper insulation. Consequently, the charges will lead to distorting the electric field and accelerating the probability of discharge. Surface fluorination is an effective technology of modifying the chemical components of polymer matrix. This paper is dedicated to investigate the surface charge dynamic behavior and trap distribution characteristics of fluorinated oil-impregnated paper under the harmonic superimposed DC voltages. And then the surface discharge tests were performed. Some conclusions can be drawn that the 3rd harmonic voltage has the most impact on the trap energy level of samples. The fluorination induces the deep trap to improve the charge dissipation.

High voltage condenser bushing is one of the important component that is widely used in the high voltage system. At high voltage levels more than 52kV the distribution of electric field in condenser bushing is irregular between the lead conductor and the grounded metallic flange. This paper studied the effects of changing in both: the number layers of aluminum foils and Oil Impregnated Paper (OIP), increasing the length of aluminum foils layers, and also increasing the thickness of OIP layer on the distribution of electric potential and electric field in condenser bushing by using Finite Element Method (FEM) and built the bushing model in ANSYS software. The harmonic analysis was performed of the bushing model at maximum value of withstand voltage test at 50Hz, from the analysis results are obtained the maximum value of electric field on the inner and outer surface of the bushing, the obtained electric field values were good and acceptable compared to the permissible electrical stress values of the dielectric insulators. This work can also aid in the design of high voltage bushing stress control, a knowledge of the electrical field distribution in bushing geometry. Moreover, the results of analysis are shown as contour plots, graphs plotted, and tables.

The paper is devoted to comparison of experimental data with theoretical predictions concerning the dependence of the current of accelerated ions on the operating voltage of a Hall thruster with an anode layer. The error made in the paper published by the authors in Plasma Phys. Rep. 40, 229 (2014) occurred because of a misprint in the Encyclopedia of Low-Temperature Plasma. In the present paper, this error is corrected. It is shown that the simple model proposed in the above-mentioned paper is in qualitative and quantitative agreement with experimental results.

An oil-paper insulation system is a key component of converter transformers as well as high voltage direct current (HVDC) bushings. It withstands not only DC voltage under normal conditions, but also impulse voltage when operating overvoltage appears. So this paper studies the surface charge behavior of double-layer oil-paper insulation under both DC and pulse voltages. From the research of different pulse voltage amplitudes, pulse numbers and polarities, conclusions can be drawn that, with the increase in pulse voltage amplitudes, DC and pulse voltages in the same polarity cause the absolute value of the initial surface potential to decrease first and then rise; while in different polarities, the charge with the same polarity as the pulse voltage increases. Considering the pulse number effect, it is obvious that the initial value increases with the increase in the pulse number, and then reaches saturation. Also, with the increase in pulse number, the decay rate decreases.

In the paper, existing research and operating experience was summarized. On the basis, the particularity of oil-paper insulation operation condition for converter transformer was combined for studying the influence of temperature on oil-paper insulation field intensity distribution of converter transformers under different AC contents within wide temperature scope (-40°C~105°C). The law of temperature gradients on space charge accumulation was analyzed. The breakdown or flashover characteristics of typical oil-paper compound insulation structure under the action of DC, AC and AC-DC superposition voltage at different temperatures were explored. The design principles of converter transformer oil-paper insulation structures in alpine region was proposed. The principle was adjusted and optimized properly according to the operation temperature scope and withstood AC-DC proportion. The reliability of transformer operation was improved on the one hand, and the insulating medium can be rationally utilized for reducing the manufacturing cost of the transformer on the other hand.

Radiation damage is the most fundamental limitation for achieving high resolution in cryo-EM, and is expected to be reduced at liquid-helium temperature. Surprisingly, cryo-EM reconstructions of apoferritin samples cooled with liquid helium showed no improvement in resolution over liquid-nitro­gen-cooled samples, but showed substantially more beam-induced particle motion., Radiation damage is the most fundamental limitation for achieving high resolution in electron cryo-microscopy (cryo-EM) of biological samples. The effects of radiation damage are reduced by liquid-helium cooling, although the use of liquid helium is more challenging than that of liquid nitrogen. To date, the benefits of liquid-nitrogen and liquid-helium cooling for single-particle cryo-EM have not been compared quantitatively. With recent technical and computational advances in cryo-EM image recording and processing, such a comparison now seems timely. This study aims to evaluate the relative merits of liquid-helium cooling in present-day single-particle analysis, taking advantage of direct electron detectors. Two data sets for recombinant mouse heavy-chain apoferritin cooled with liquid-nitrogen or liquid-helium to 85 or 17 K were collected, processed and compared. No improvement in terms of resolution or Coulomb potential map quality was found for liquid-helium cooling. Interestingly, beam-induced motion was found to be significantly higher with liquid-helium cooling, especially within the most valuable first few frames of an exposure, thus counteracting any potential benefit of better cryoprotection that liquid-helium cooling may offer for single-particle cryo-EM.

The effluents generated by textile industries are extremely toxic and dangerous to the environment. In fact, new treatment technologies for recalcitrant effluents have been tested for high dye removal efficiency. Among these technologies, electrocoagulation has been highly promising, due to its excellent results coupled with a low operating cost. This study evaluated the electrocoagulation/electroflotation process efficiency on the removal of Eriochrome Black textile dye from aqueous solution. All the experiments were carried out using aluminum electrodes due to their availability and low cost. The parameters investigated during the experiment were: electrolysis experiment time, NaCl concentration, aqueous solution pH and electric potential. In this context, the best results considering the operational parameters studied were electric potential of 7 V, values of pH low to neutral (2–7) and NaCl concentration of 2 g L−1. It has also been observed that a time of 55 min of electrolysis is sufficient for a satisfactory result, reaching a color removal efficiency of 98.5%.

The objective of this research is to study the combined influences of applied electric and magnetic fields on the two-phase peristaltic motion of nanofluid through a curved channel. A two-phase model of a nanofluid, Maxwell’s model of thermal conductivity [1], and no-slip velocity and thermal boundary conditions have been used in this study. Hall effects, Joule heating (due to magnetic and electric fields), and viscous heating aspects are under consideration. Governing equations for the present flow configuration have been modeled and simplified by enforcing the lubrication scheme. Debye-Huckel approximation is used to obtain the analytical solution of the electric potential function (Poisson-Boltzmann equation). Resulting expressions are solved numerically through the NDSolve command in Mathematica and plotted in order to understand the effects of different dimensionless parameters on the temperature, stress, heat transmission rate, and fluid’s velocity. Graphical results demonstrated that the thermal transmission rate is augmented by increasing the Hartmann number, Brinkman number, and Debye-Huckel parameter while decreases for zeta potential ratio, Joule dissipation parameter, and electro-osmotic velocity. A decrease in axial velocity is noted near the lower wall for higher values of $${m}^{\ast}$$ .

Nickel–molybdenum (Ni–Mo) alloys are well studied as highly effective electrocatalyst cathodes for water splitting. Understanding deactivation pathways is a key to improving the performance of these catalysts. In this study, in situ characterization by UV/Vis spectroscopy and AFM of the morphology and Mo leaching of an Ni–Mo electrocatalyst was performed with the goal of understanding the stability and related Mo leaching mechanism. Switching the potential towards higher overpotentials results in a nonlinear change in Mo leaching. Multiple processes are proposed to take place, such as a decrease in the extent of Mo oxidation at the cathode induced by more strongly reducing potentials, while simultaneously the increase in the local pH at the cathode due to the hydrogen evolution reaction causes more Mo leaching. The change in capacitance of these materials depends strongly on the change in surface composition and not only on the surface area. In situ UV/Vis spectroscopy showed that Mo leaching is a continuous process over the course of 4 h of operation. Finally, the material was deposited on different substrates and the effect on Ni–Mo stability was studied. The substrate has a significant, albeit complex, influence on the stability and activity of Ni–Mo cathodes. In terms of stability in 1 m KOH, Ni–Mo was found to be best deposited on stainless steel substrates operated at low overpotentials, on which it showed nearly no change in capacitance and exhibited low Mo leaching., Fulfilled potential: Ni–Mo is studied as electrocatalyst for the hydrogen evolution reaction. The effect of four substrate materials on its stability is investigated. Furthermore, the effect of applied voltage and current is studied to explore how intermittent electricity results in electrode destabilization. The least Mo leaching is found at low overpotentials with steel as substrate.

The effect of three electric potentials (EP) (+104, -187 and -279 mV) applied to the denitrifying process was explored. It was observed that the denitrifying sludge was able to support the oxidation of

Currently, energy conversion methods in nanochannels have been developed for both fundamental sciences and technological applications. Graphene oxide membranes with excellent properties possess potential applications in numerous fields. Due to the confinement of nanocapillaries within graphene oxide membranes and the mobility difference of ions, an electricity generation process has been achieved using graphene oxide membranes. In this study, for the first time, the influence of source concentration, applied pressure and membrane thickness was investigated on electricity generation in aqueous environment. The results revealed that these three factors could successfully control the electricity generation with graphene oxide membranes. Electrical potential difference would become larger with increasing the source concentration and membrane thickness. In contrast, the applied pressure was not well-suited to capture energy from sources. This provided new insights into the design and utilization of graphene oxide films for highly efficient energy harvesting.

Nacre-mimetic 2D nanofluidic materials with densely packed sub-nanometer-height lamellar channels find widespread applications in water-, energy-, and environment-related aspects by virtue of their scalable fabrication methods and exceptional transport properties. Recently, light-powered nanofluidic ion transport in synthetic materials gained considerable attention for its remote, noninvasive, and active control of the membrane transport property using the energy of light. Toward practical application, a critical challenge is to overcome the dependence on inhomogeneous or site-specific light illumination. Here, asymmetric photonic-ionic devices based on kirigami-tailored graphene oxide paper are fabricated, and directional nanofluidic ion transport properties therein powered by full-area light illumination are demonstrated. The in-plane asymmetry of the graphene oxide paper is essential to the generation of photoelectric driving force under homogeneous illumination. This light-powered ion transport phenomenon is explained based on a modified carrier diffusion model. In asymmetric nanofluidic structures, enhanced recombination of photoexcited charge carriers at the membrane boundary breaks the electric potential balance in the horizontal direction, and thus drives the ion transport in that direction under symmetric illumination. The kirigami-based strategy provides a facile and scalable way to fabricate paper-like photonic-ionic devices with arbitrary shapes, working as fundamental elements for large-scale light-harvesting nanofluidic circuits.

Relativistic electron diffraction depends on linear and quadratic terms in the electric potential, the latter being neglected in the frequently used relativistically corrected Schrödinger equation. Conventional tabulations for electron scattering and its large-angle extrapolations can be amended in closed form by a universal correction based on the screened Coulomb potential squared., Relativistic electron diffraction depends on linear and quadratic terms in the electric potential, the latter being neglected in the frequently used relativistically corrected Schrödinger equation. The quadratic electric potential term modifies atomic scattering amplitudes in particular for large-angle scattering and backscattering. The respective correction increases with increasing scattering angle, increasing atomic number and increasing kinetic energy. Conventional tabulations for electron scattering and its large-angle extrapolations can be amended in closed form by a universal correction based on the screened Coulomb potential squared.

Analytical solutions of the Schrödinger equation for the one-dimensional quantum well with all possible permutations of the Dirichlet and Neumann boundary conditions (BCs) in perpendicular to the interfaces uniform electric field [Formula: see text] are used for the comparative investigation of their interaction and its influence on the properties of the system. Limiting cases of the weak and strong voltages allow an easy mathematical treatment and its clear physical explanation; in particular, for the small [Formula: see text], the perturbation theory derives for all geometries a linear dependence of the polarization on the field with the BC-dependent proportionality coefficient being positive (negative) for the ground (excited) states. Simple two-level approximation elementary explains the negative polarizations as a result of the field-induced destructive interference of the unperturbed modes and shows that in this case the admixture of only the neighboring states plays a dominant role. Different magnitudes of the polarization for different BCs in this regime are explained physically and confirmed numerically. Hellmann-Feynman theorem reveals a fundamental relation between the polarization and the speed of the energy change with the field. It is proved that zero-voltage position entropies [Formula: see text] are BC independent and for all states but the ground Neumann level (which has [Formula: see text]) are equal to [Formula: see text] while the momentum entropies [Formula: see text] depend on the edge requirements and the level. Varying electric field changes position and momentum entropies in the opposite directions such that the entropic uncertainty relation is satisfied. Other physical quantities such as the BC-dependent zero-energy and zero-polarization fields are also studied both numerically and analytically. Applications to different branches of physics, such as ocean fluid dynamics and atmospheric and metallic waveguide electrodynamics, are discussed.

We introduce a high-performance molecular sensor using self-corrugated chemically modified graphene as a three dimensional (3D) structure that indicates anisotropic charge distribution. This is capable of room-temperature operation, and, in particular, exhibiting high sensitivity and reversible fast response with equilibrium region. The morphology consists of periodic, “cratered” arrays that can be formed by condensation and evaporation of graphene oxide (GO) solution on interdigitated electrodes. Subsequent hydrazine reduction, the corrugated edge area of the graphene layers have a high electric potential compared with flat graphene films. This local accumulation of electrons interacts with a large number of gas molecules. The sensitivity of 3D-graphene sensors significantly increases in the atmosphere of NO2 gas. The intriguing structures have several advantages for straightforward fabrication on patterned substrates, high-performance graphene sensors without post-annealing process.

Thermodynamic properties of the one-dimensional (1D) quantum well (QW) with miscellaneous permutations of the Dirichlet (D) and Neumann (N) boundary conditions (BCs) at its edges in the perpendicular to the surfaces electric field are calculated. For the canonical ensemble, analytical expressions involving theta functions are found for the mean energy and heat capacity for the box with no applied voltage. Pronounced maximum accompanied by the adjacent minimum of the specific heat dependence on the temperature T for the pure Neumann QW and their absence for other BCs are predicted and explained by the structure of the corresponding energy spectrum. Applied field leads to the increase of the heat capacity and formation of the new or modification of the existing extrema what is qualitatively described by the influence of the associated electric potential. A remarkable feature of the Fermi grand canonical ensemble is, at any BC combination in zero fields, a salient maximum of observed on the T axis for one particle and its absence for any other number N of corpuscles. Qualitative and quantitative explanation of this phenomenon employs the analysis of the chemical potential and its temperature dependence for different N. It is proved that critical temperature of the Bose-Einstein (BE) condensation increases with the applied voltage for any number of particles and for any BC permutation except the ND case at small intensities what is explained again by the modification by the field of the interrelated energies. It is shown that even for the temperatures smaller than the total dipole moment may become negative for the quite moderate . For either Fermi or BE system, the influence of the electric field on the heat capacity is shown to be suppressed with N growing. Different asymptotic cases of, e.g., the small and large temperatures and low and high voltages are derived analytically and explained physically. Parallels are drawn to the similar properties of the 1D harmonic oscillator, and similarities and differences between them are discussed.

This paper presents an EHD model for SPH based on a charge-conservative approach. Compared with the leaky dielectric model, the EHD model used in this paper was charge conserved, since no term in the charge conservation equation was neglected. An implicit SPH formula for calculating the electric potential from the electrical properties of the previous time step was constructed, based on the electric potential Poisson equation and the charge conservation equation. The SPH formulas of the electric field and the charge density were also presented. To implement the EHD boundary condition accurately, a scheme, with two kinds of EHD boundary dummy particles, was developed. Both static and hydrodynamic numerical tests were conducted, and the accuracy of the proposed EHD model for SPH was verified by comparison with the results of analysis, the FVM method and the existing ISPH with the leaky dielectric model. This study provides an efficient method for simulating complex EHD problems with SPH.

In high voltage transmission porcelain materials are important one. To mount the transmission line on a transmission tower we need an insulation material. Many literatures deal about the silicon and rubber-based insulators. In this paper the porcelain is modelled as FEM model using the PDE tool and electric potential distribution is analyzed. the PDE tool come in handy to draw the shape of the insulator. In this paper the straight shed and alternate shed insulators are analyzed with the MATLAB PDE tool and results are analyzed. then using some random water droplets in the insulator, the impact is observed.

Alternative models of the electrical resistivity of the soil to the well-known constant piecewise multilayer model are presented in this paper. By their special features, the proposed models lead to reasonably simple semi-analytical expressions for the electric potential. The parameters associated with these models are obtained from apparent resistivity measurements using an optimization procedure. The proposed models allow obtaining a continuous piecewise resistivity profile as a function of depth from the soil surface. From the full definition of the models, the grounding resistance of several electrodes is calculated and compared with that obtained from the classic multilayer model. Finally some application examples including data from field measurements are considered in this paper.

In this paper, the complete explicit solution for physical fields around a micro-hole is solved with the simultaneous consideration of the strain gradient elasticity, the direct flexoelectricity, and the converse flexoelectricity. First, the higher-order Navier-like governing equations are proposed for an isotropic flexoelectric solid by using an extended linear theory of flexoelectric materials considering the coupling between the strain gradient and the polarization, and conversely between the polarization gradient and the strain. Second, the displacement, the electric potential, and the polarization are successfully obtained by solving the corresponding boundary value problems for a micro-hole model. Finally, the influence of the strain gradients and the flexoelectric effect on the mechanical fields and the electric responses are studied around the micro-hole in flexoelectric solids, and the size effects of the direct flexoelectricity and the converse flexoelectricity are also investigated. The results indicate that an electric response can be obviously induced by a mechanical loading due to the direct flexoelectricity. Conversely, a mechanical strain can be produced by an electric field through the converse flexoelectricity. The size dependence of both the direct flexoelectricity and the converse flexoelectricity is also successfully predicted in this paper, in the form that the flexoelectricity significantly increases with the decrease in the sample size.

An ion-flow field is very important for the design of an HVDC transmission line. Due to the space ions resulting from corona discharge, there are few practical methods to measure the space electric fields around HVDC transmission lines. In this paper, a compensation method is presented to measure the space potential in the ion-flow field. The space potential can be obtained by applying an adjustable voltage source to a suspended conductor, increasing the voltage step-by-step and measuring the current flowing through the voltage source or the ground-level ion current density under the suspended conductor. When the current is equal to zero or the ground-level ion current density is equal to that without the suspended conductor, the output voltage of the voltage source is the space potential to be measured. The paper first introduces the principle of the measurement method. Then, the feasibility of the method is testified on unipolar and bipolar reduced-scale models. Finally, the measured results are discussed and are compared with the results by the numerical method.

The papers in this special issue present a selection of high quality research papers on wearable and flexible integrated sensors for screening, diagnostics, and treatment. Emerging flexible and wearable physical sensing devices create huge potential for many vital healthcare and biomedical applications including artificial electronic skins, physiological monitoring and assessment systems, therapeutic and drug delivery platforms, etc. Monitoring of vital physiological parameters in hospital and/or home environments has been of tremendous interests to healthcare practitioners for a long time. Robust and reliable sensors with excellent flexibility and stretchability are essential in the development of pervasive health monitoring systems with the capability of continuously tracking physiological signals of human body without conspicuous discomfort and invasiveness.

Publisher Copyright: Author A lightning strike is considered one of the most risky natural phenomena that can lead to human harmful and the surrounding soil layers. To tackle this issue, this article investigates the influence of direct lightning characteristics in terms of human body safety. Specifically, such investigation is carried out on the effect of resistivities of two-layer soils on human safety when lightning stroke hits the towers of the high voltage transmission lines (HVTLs). The merit of the proposed study is that the soil ionization phenomenon is taken into consideration. Further, the study focuses on the current passing through the human heart, when step and touch (contact) voltages are generated by grounding potential rise, caused by direct lightning strikes transmission tower and the produced potential rise that a person could be exposed. Also, studying the effects of peak current and time of lightning strokes are investigated. Additionally, the paper presents the effect of different reflection factors on human safety.For validation purposes, the ATP program is used in the simulation of the grounding system as well as the human body model. Numerous simulations were accomplished in order to examine the behavior of the current passing through with the human heart. Based on the simulation results, it was concluded that the soil characteristics have superior influences on the contact and step potentials and, accordingly, the survival threshold.

In practical engineering, electricity theft detection is usually performed on highly imbalanced datasets (i.e., the number of fraudulent samples is much smaller than the benign ones), which limits the accuracy of the classifier. To alleviate the data imbalance problem, this paper proposes simple data augmentation tricks (SDAT) to boost performance on electricity theft detection tasks. SDAT includes five simple but powerful operations: adding noises to electricity consumption readings, drifting values of electricity consumption readings, quantizing electricity consumption readings to a level set, adding a fixed value to electricity consumption readings, and adding changeable values to electricity consumption readings. In addition, eight potential tricks are also mentioned. Numerical simulations are conducted on a real-world dataset. The simulation results show that SDAT can significantly boost the performance of different classifiers, especially for small datasets. Besides, specific suggestions on how to select parameters of SDAT are provided for its migration use to other datasets.

This paper discusses the effects of notches in spacers of gas insulated switchgear (GIS) to hold conductor rod to prevent it from sliding down prior to installation. The spacers in question use epoxy resins as its main material with relative permittivity of 3.5. This paper compares the design of spacers without any notches and spacers with 3 notches in its conductor cavity. The results of this paper suggest that spacer with notches has higher electric field intensity compared to spacer without notches. Spacers with notches has maximum electric field intensity of 53.61 KV/cm while the spacers without notches has maximum electric field intensity of 27.84 kV/cm.

The paper focuses on the identification of potential local attack threats in embedded systems used in automotive applications. One of the objectives of the paper is to show that cyber-attacks may result in taking control over a module in an electric vehicle. On the other hand, the article suggests a low-cost protection method that can be used for increasing the level of CAN bus transmission security.

The large-scale access of current-controlled inverters (CCIs) has caused weak grids and a series of instability issues. On the contrary, because of can actively support the weak grid, voltage-controlled VSGs (VC-VSGs) have become a potential choice for high-penetration renewable energy power generation. Multi-paralleled CCI and VC-VSG grid-connected systems (MCVGSs) are account for an increasing proportion of the distributed generation systems. This paper focused on the influence of short-circuit capacity ratio (SCR) and VC-VSG capacity ratio (VSGCR) on the MCVGS small-signal stability. Then, this paper proposes an SCR-based VC-VSG capacity distribution method, which can determine the VC-VSG capacity required to maintain a certain MCVGS stability margin in a weak grid. Finally, simulation results validate the analysis and the proposed method.

This paper examines Peukert's law for lithium-ion capacitors (LICs) during constant power discharge processes. Peukert's law is a relationship originally developed to characterize the charge delivery capability of lead-acid batteries: when a higher discharge current is applied, less charge is released. As a hybrid energy storage technology, a LIC is normally composed of a graphite negative electrode typically used in lithium-ion batteries and an activated carbon positive electrode usually used in supercapacitors. To evaluate the LIC technology for potential aerospace applications, this paper investigates the LIC energy delivery pattern when a constant power load is applied. By performing extensive experiments, this paper verifies that Peukert's law applies to LICs in the power mode: when the applied discharge power decreases, more energy is delivered. Furthermore, this paper studies the LIC Peukert constant dependence on its terminal voltage. Experimental results suggest that this dependence is similar to that of supercapacitors.

This research paper aims to investigate the optimal design of grading rings for high-voltage polymeric insulators in an actual power transmission system, with a focus on improving the electrical representation of the insulator strings. One such subsidiary accessory commonly used with porcelain and polymer insulator strings is the grading ring, which is employed to improve the electric field and voltage distribution surrounding the insulator string. The efficiency of insulator strings can be enhanced by grading rings, as they facilitate a more linear potential division along the strings. The design parameters of grading rings significantly influence their performance on insulator strings. In this study, we examine the optimal design of the grading rings of high-voltage polymer insulators, since no uniform design methodology has been developed for high-voltage polymer insulators, and their optimization is currently the subject of many research studies. The electric field on an outdoor polymeric insulator is examined using finite element method (FEM) software and COMSOL Multi-Physics program. A 2D model is utilized to simulate a 220 kV polymeric insulator. The effectiveness of high-voltage polymeric insulators greatly depends on the dimensions and locations of the grading rings. Therefore, the impacts of the radius of the grading ring and that of its tube and the tube’s vertical position are thoroughly investigated, under dry and humid conditions. To achieve this objective, a search algorithm is employed to adjust the dimensions and locations of the grading ring. The optimization approach in this study is based on determining the maximum electric field across the insulator surface, while ensuring that it remains below the corona initiation level.

Many gamification approaches use a one size fits all approach. Different gamification player types and associated preferences have been proposed, such as the gamification player type Hexad. According to the Hexad, people prefer different gameful activities, such as exploration, social activities, or competition. Similarly in hobbies, different things motivate and interest different people, such as some finding board games interesting, while others like hiking and going on camping trips. We propose that a person’s hobbies and interests provide an insight into what type of person they are, indicating what they might like, and could have a connection to gameful system preferences. In this paper, we explore the relationship between free-time activities and gamification player types, to enable earlier and faster detection of the player types and their preferences. The research was conducted by building a survey to measure the free-time activities of people and also measure the Hexad player type as defined by Marczewski and Tondello et al. Significant relationships were found between free-time activity variables “Active physical exerciser”, “Audience of cultural events”, and the player type Philanthropist. Overall, these results indicate that free-time activities can have correlations with player types and reported hobbies can be used as a proxy when selecting personalized gamification approaches. Post-print / Final draft

The object of this paper is the Saint-Venant torsion of a radially non-homogeneous, hollow and solid circular cylinder made of orthotropic piezoelectric material. The elastic stiffness coefficients, piezoelectric constants and dielectric constants have only radial dependence. This paper gives the solution of the Saint-Venant torsion problem for torsion function, electric potential function, Prandtl’s stress function and electric displacement potential function.

Electro-osmosis is a suitable method for the consolidation of soft soil. However, the significant potential loss caused by the cracking of the soil near the electrode in the later stages of electro-osmosis hinders further improvement of its efficiency. Dynamic loading is applied to overcome this problem. The dynamic loading activation time is considered to strongly influence the performance of the combined electro-osmosis-dynamic loading process. In this paper, the maximum current ratio (MCR) is proposed as an index of the dynamic loading activation time. Laboratory tests were performed with different dynamic loading activation times to confirm the influence of the dynamic loading time on electro-osmosis consolidation. During the combined processes of dynamic loading and electro-osmosis, the current, electric potential, discharged water, and surface settlement were monitored. In the following testing, the water content and undrained shear strength were measured. Compared with the electro-osmosis method alone, electro-osmosis and dynamic loading was found to yield superior performance improvement. The method described in this paper to determine the optimal dynamic loading activation time as a function of the MCR, and electro-osmosis, exhibits potential as an improved approach for the consolidation of soft soil in engineering practice.

An increasing need for fast and reliable models has led to a continuous development of Fourier-based (FB) analytical modeling. This paper presents an overview of the techniques that are currently available in FB modeling for electric machines. By coupling that overview to the most relevant literature related to the subject, an interesting starting point is provided for anyone who wants to use or improve FB models. The following seven aspects of FB models are discussed in detail: 1) the magnetic potential (scalar or vector potential); 2) the coordinate system and the solution of the partial-differential equations for each magnetic potential and for each coordinate system; 3) the way in which time dependence is accounted for; 4) the implementation of the source terms; 5) the possibilities to account for slotted structures; 6) the modeling of eccentricity; and 7) the post-processing computation of physical quantities, such as flux density, electromotive force, torque, losses, and eddy currents in conductive objects. Furthermore, this paper gives the closed form solution of the Laplace, Poisson, and Helmholtz equations in each coordinate system. In addition, this paper tackles other important features of FB models such as computational time reduction and coupling the machine model to an electric circuit.

Detailed physics of the third quadrant electrical characteristics of 1.2-kV rated 4H-SiC accumulation (Acc) and inversion (Inv) channel MOSFETs, based on experimentally measured data and TCAD numerical simulations, are described in this paper for the first time. The power MOSFETs with various channel lengths (0.3, 0.5, 0.8, 1.1 $\mu \text{m}$ ) used in this paper were fabricated in a 6-in commercial foundry. Numerical simulations verified that there are two current paths in the third quadrant: 1) through the base region and 2) through the p-n body diode. This paper demonstrates that the Acc MOSFETs have a smaller third quadrant knee voltage ( ${V}_{{\text {knee}}})$ of −1.2 V compared with −1.9 V for the Inv MOSFETs (at ${V}_{g} = {0}$ V and room temperature). Numerical simulations show that this difference is due to a smaller potential barrier for electron transport from the drain to the source in the base region for accumulation channel devices than inversion channel devices. Acc devices are shown to have a lower voltage drop in the third quadrant.

This paper presents a neutral-point deviation and ripple compensating control method applied to a three-level neutral-point-clamped (NPC) converter. The neutral-point deviation and its harmonic components are analyzed with a focus on the average current flowing through the neutral-point of the dc link. This paper also proposes a control scheme compensating for the neutral-point deviation and dominant harmonic components under generalized unbalanced grid operating conditions. The positive and negative sequence components of the switching functions and ac input currents are employed to accurately explain the behavior of three-level NPC converter. Simulation and experimental results are presented to verify the validity of the proposed method.

This paper presents a novel approach to test surface material charging under electron flux representative of space conditions below 400 keV. The experimental protocol used to test space material electrical properties consists in adapting the electron flux distribution to mimic worst case spectra met in space. Input environments are taken from Kp > 5 specifications at geosynchronous orbit (GEO) and from the analysis of both RBSP and LANL spacecraft data at middle Earth orbit (MEO) and GEO. Experimental results using GEO specifications show that the surface potential strongly depends on the energetic particle flux. Above a given > 100-keV electron flux, the radiation-induced conductivity tends to govern the charging dynamics. A numerical analysis based on the environments selected in this paper shows that charging levels could be larger at MEO than at GEO.

This paper reports on the detection of hydrogen (H2) gas by utilizing a gate-all-around nanowire (NW) junctionless (JL) transistor as a sensor. The effects of temperature and pressure are considered in the transduction process through a change in gate workfunction of palladium (Pd) gate after exposure to $H_{2}$ gas. The analysis is performed through TCAD simulations, and an analytical model is developed in the subthreshold regime of device operation at a relatively low drain bias of 0.5 V. The performance of the NW JL transistor gas sensor is evaluated through the OFF-current-based sensitivity ( $S_{I}$ ) and sensitivity based on threshold voltage shift ( $S_{V}$ ). The analytical model developed for $S_{I}$ and $S_{V}$ shows a very good consistency with simulation data. The anomalous behavior of threshold voltage with temperature in the NW JL transistor under the influence of $H_{2}$ gas is analyzed in detail. This paper predominantly focuses on utilizing the NW JL transistor for low-power gas sensing, specifically at low pressures (10−15–10−10 torr), for temperatures ranging from 250 to 450 K. Insights into physical mechanisms within the device due to the transduction process are highlighted for optimum sensing.

The dielectric screening property of a semiconductor is very crucial for the electrical characteristics of a MOSFET, and which can be described mathematically by Poisson equation via the permittivity. While the theory and experiments have corroborated the permittivity reduction of nanoscale Si, this paper studies the electrical characteristics of MOSFETs considering the reduced channel permittivity by quantum transport simulations. It is found that the channel permittivity reduction may mitigate the short-channel effects, showing subthreshold swing improvement and threshold voltage shift of MOSFETs in nanoscale. Compared to quantization effects, the positive and negative impacts of the channel permittivity reduction on the devices in particularly nanoscale have been investigated. This paper elucidates the necessity of considering semiconductor permittivity reduction for nanoscale device design and simulations.

This paper demonstrates a post-fabrication technique for creating highly compliant structures inside a hermetic, wafer-scale encapsulation process. Single crystal silicon micro-tethers were fabricated alongside compliant structures to temporarily provide additional anchoring and increased device rigidity during the fabrication process. This technique mitigates in-process stiction for compliant devices by tethering the large, free-moving structures during fabrication. After successful fabrication, the micro-tethers can be selectively removed by two methods. The first method utilizes a potential voltage difference across the device. Joule heating can be concentrated in the micro-tether and the device separated after supplying requisite heat energy. The second method utilizes mechanical fracturing where a large external force is applied to separate the device from the tether. Micro-tethers in this paper were attached to differential resonant beam accelerometers, and were designed for detachment by each method: Joule heating and mechanical fracture. Our results show that the $40\mu \text{m}$ thick device can be successfully detached by both methods, indicated by the device sensitivity increase from ~100 Hz/g to ~400 Hz/g. [2018-0091]

Objective: Unipolar pulses have been used in cell electrofusion over the last decades. However, the problem of high mortality with unipolar pulses has not been solved effectively. The cell fusion rate is restricted by cell mortality. By using the advantages of bipolar pulses which cause less cell damage, this paper attempts to use bipolar pulses to increase the cell fusion rate. Methods : the transmembrane voltage and pore density of cells subjected to unipolar/bipolar pulses were simulated in COMSOL software. In an experiment, two 40 μs unipolar and two 20–20 μs bipolar pulses with electric fields of 2, 2.5, and 3 kV/cm were applied to SP2/0 murine myeloma cells. To determine the cell fusion rate and cell mortality, cells were stained with Hoechst 33342 and propidium iodide. Results: the simulation in this paper showed that a high transmembrane voltage and a high pores density were concentrated only at the contact area of cells when bipolar pulses were used. The results of the cell staining experiment verified the simulation analysis. When bipolar pulses were applied, the cell mortality was significantly reduced. In addition, the cell fusion rate with bipolar pulses was almost two times higher than that with unipolar pulses. Conclusion: for cell electrofusion, compared with unipolar pulses, bipolar pulses can not only reduce the cell mortality remarkably but also improve the cell fusion rate obviously. Significance: this paper introduces a novel way to increase the fusion rate of cells.