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An closed oil circulating system with plane electrode was built to study the effect of space charge on oil flow electrification under DC voltage. The results reveal that with the increase of applied voltage, the streaming current was always enhanced. However, the polarity of streaming current depends on the sample configuration. If the negative high voltage electrode was exposed to oil layer, streaming current was negative. Otherwise streaming current had a tendency to be positive as applied voltage increased. In experimental model without exposed electrode, the polarity of streaming current was always positive. And the amplitude of streaming current was related to the number of insulating papers placed under electrode. More craft papers placed under negative high voltage electrode led to the increase of streaming current. Based on the bipolar transport model, a new simulation method is proposed to study the effect of charge injection and transportation on flow electrification under DC voltage. The simulation results agree well with the experimental result. [ABSTRACT FROM AUTHOR]

The instability of amorphous indium–gallium–zinc oxide (a-IGZO) thin-film transistors (TFTs) under ultraviolet (UV) light was thoroughly investigated in this paper. Unlike in a darkened state, an off-state leakage current can be found in the dual-sweep I–V transfer curve of a-IGZO TFTs under UV light illumination. Furthermore, despite the same UV light condition, the forward sweep and reverse sweep show different I–V curves, representing two different physical mechanisms. First, the subthreshold swing degradation and threshold voltage shift to the negative direction in the forward sweep are due to the total channel barrier lowering and can be confirmed by changing the light exposure region. Second, in the reverse sweep, the suggested back-channel leakage current can be controlled by dual-gate TFTs. UV light exposure of the metal–insulator–semiconductor–metal structure verifies that the off-state leakage current passes through the back channel in a reverse sweep. Finally, the physical mechanism links between forward and reverse sweeps have comprehensive interpretation in this paper. [ABSTRACT FROM AUTHOR]

In this paper, a new configuration of dielectric-barrier discharge (DBD) reactor with three electrodes was manufactured and used to produce ozone. Designed flatly, this reactor is capable of establishing three different discharge modes from type of the volume and surface discharges, without modifying its internal structure. The aim of presenting this paper is to experimentally analyze the three discharge modes and their combination using a second channel to produce ozone. The two reactor channels are identical in terms of dimensions, material, and manufacturing process. Two frequency-adjustable pulse generators of the same electrical characteristics and two high-voltage transformers were used in the course of the experiments. The applied sinusoidal voltage is from 0 to 12 kVp-p. The frequency range was determined and fixed for all three discharge modes for the highest ozone concentration at a fluctuation rate of 1 L/min. Effects of increasing the applied voltage on the obtained concentration from the three different discharge modes were experimentally analyzed. Using the provided inlets–outlets, the effect of flowing gas through the length and width of the discharge area on ozone concentration was investigated, and appropriate flow directions were determined for the flowing gas under either of the three discharge modes. Experimentally results have been done for this three discharge modes as well as hybrid modes. The maximum ozone production rate achieved up to 14.52 g/h in the series combination of two different volume discharge. At 96% oxygen purity, ozone production yield, in two modes volume discharge VaDBD and surface discharge SDBD, have been improved up to 529.87 g/kWh. However, the total input power of the entire system is 120.2 W. [ABSTRACT FROM AUTHOR]

The past measurements of the plasma density and potential profiles near the exit of the keeper electrode in a hollow cathode device suggested that turbulent ion acoustic fluctuations and ionization instability in the cathode plume significantly increased the energy of the ions that flow from this region. The lifetime of keeper electrode is limited by sputtering or ion bombardment of the Molybdenum surface exposed to the discharge plasma. Increases in the cathode gas flow reduce the amplitude of the fluctuations and the number and energy of the energetic ions, which decreases the erosion rate of the keeper electrodes. However, as the cathode gas flow is raised for a given discharge current, the performance of a 5-kW Annular-Geometry Ion Engine (AGI-Engine) declines. There is a strong relationship between the performance and the lifetime of the ion thruster. To validate whether the 20-A hollow cathode satisfied China’s communication satellite platform’s application requirement for North-South station keeping, this paper analyzed the effect of the cathode gas flow on the performance and the lifetime of the AGI-Engine. Different from the previous methods, this paper first tracked the movement of energetic ions generated in the plume of the hollow cathode, predicted erosion rates, found where they hit the keeper electrode, and then determined the amount of material that they sputtered. A review of past experimental results was presented first. Next, based on the existing experimental data, theoretical analysis and numerical calculations were performed to determine the optimum gas flow range and the performance curve of the 20-A hollow cathode. The results showed that the primary erosion mechanism of the keeper electrode was caused by impact from Charge Exchange Xenon (CEX) ions, which caused the cathode orifice to be widened and attenuated over time. However, heavy double xenon ($\text{X}_{\text{e}}^{++}$) ions, which struck the keeper electrode more severely than CEX ions, were the most crucial factor that limited the lifetime of the 20-A hollow cathode due to their high energy and large mass. [ABSTRACT FROM AUTHOR]

The groundings of the power distribution, signaling, and power systems of a railway system are individually performed to realize fail safe, and the groundings are often installed in close proximity. Thus, when a grounding electrode is invaded by a lightning current, its ground potential rises together with the potential of the adjacent grounding electrodes; hence, there is a possibility of a large overvoltage being applied to the connected devices. In this paper, we have investigated the potential spread between two rod-shaped electrodes widely used in the grounding of the power, signal, and distribution systems of a railway system using the finite-difference time-domain method. The results of this paper are organized in such a way that the extent of the potential spread to the neighboring grounding electrodes can be understood from information such as the grounding resistivity at the installation location of the ground electrode and the wavefront duration of the lightning current, and these findings will be useful for grounding design. We also investigate the effect of the insulator between two neighboring electrodes to prevent the potential spread. [ABSTRACT FROM AUTHOR]

The interest in the use of atmospheric-pressure plasma jets (APPJs) is constantly growing. APPJs offer various ranges for applications, such as wound healing, cancer treatment, and dental care. The complex plasma chemistry plays an important role in each of these fields but is often poorly understood. In this paper, the production of atomic oxygen in a radio frequency helium–oxygen plasma is investigated by means of a numerical simulation. A 1-D discharge of an atmospheric-pressure plasma jet is created with the plasma module of COMSOL Multiphysics, using a set of 25 reactions. Many 1-D simulations usually cannot estimate the power deposition in a correct way because of suspected arising losses, such as radiation and inefficiencies of the external circuit. In order to match the experimental power deposition of 13 W, high voltages (855 V) are required in the model. Such high voltages cause changes in the plasma characteristics like a switch in the glow mode. The impact of the voltage on the plasma is investigated by the comparison of a low-voltage (325 V) simulation, which matches the experimental oxygen production, and a high-voltage (855 V) simulation, which matches the experimental power deposition. Outcomes of this paper further support the idea that the power deposition measured in experiments is higher than the actual power deposition coupled to the plasma. [ABSTRACT FROM AUTHOR]

Paschen’s law gives the inception voltage for an electrical discharge as a function of the product of gas pressure and the gap distance between the two infinite planar electrodes. It is known that the deviations from Paschen’s law occur when the temperature is increased. Historically, two theoretical corrections, the Peek and Dumbar corrections, are proposed to predict the deviation from Paschen’s law by increasing the temperature. To carry out an experimental investigation on the deviation from Paschen’s law by increasing the temperature, a customized system was designed, which can operate at temperatures up to 400 °C and at pressure up to 1 MPa, calculated at room temperature, with an interelectrode distance between $100~\mu \text{m}$ and 6.6 mm and an error on the interelectrode distance measurement of $20~\mu \text{m}$. In this paper, first, the results from the experimental investigation on the deviation from Paschen’s law at temperature up to 400 °C are presented. The results are then compared with theoretical corrections, and finally, a theory to explain the results is proposed and discussed. [ABSTRACT FROM AUTHOR]

This paper embodies the results of experimental studies of a dielectric barrier discharge low-temperature nonequilibrium plasma reactor that runs in air and nitrogen at atmospheric-pressure conceived for surface treatment applications. A homemade reactor, of typical plane-to-plane geometry with the dielectric covering the upper electrode which is stressed by a high voltage (40 kV, 3–20 kHz) is used. Electrical signals (current and voltage), optical emission spectroscopy records, and total light emission measured by photomultiplier have been analyzed and used to distinguish different plasma regimes which are studied for the treatment of a lignocellulosic material (sugarcane bagasse). In the filamentary discharge regime, the gas temperature of few tens of degree Celsius above the ambient one was determined, the electronic temperature of some electronvolts and electron density in the range of 1012–1013 cm−3 were estimated. Plasma treated pellets of sugarcane bagasse were analyzed by diffuse reflectance infrared Fourier transform spectrometry and the relative results obtained under filamentary discharge regime have shown significant degradation of the lignin macromolecule. It has been shown important modifications on the lignocellulosic material, namely, the plasma attacks drastically the lignin bonds. Strong modification of lignin was observed near wavenumber of 3400 cm−1, due to stretching vibrations of OH, and for the band 1114 cm−1 which is related to C=C and C=O stretching. Severe decrease of the band intensity 1596 cm−1, which due to C=C stretching and C=O, is also a result of the treatments done in this paper. [ABSTRACT FROM AUTHOR]

In modern electronic devices, a variety of novel materials have been introduced such as transition metal oxides, chalcogenides, ferroelectric, and magnetic materials. The electrical response of such materials, used also as active layers, is strongly affected by atomic defects, which affect device performances, variability, and reliability. Extracting the defect properties (i.e., density, energy, and atomic nature) is, thus, crucial to both engineer the performances of electron devices and correctly project their scaling potential and reliability. In this paper, we propose a simple method to extract the atomic properties of defects from the thermal activation energy of the leakage current using a charge trapping relaxation model. [ABSTRACT FROM AUTHOR]

This paper reports the fabrication of MEMS-based guided two-beam piezoelectric energy harvester for low-frequency operation. A highly c-axis-oriented zinc oxide thin film of 2.5- $\mu \text{m}$ thickness covered with 0.5- $\mu \text{m}$ plasma-enhanced chemical vapor deposition SiO2 is sandwiched between the aluminum electrodes to form split electrodes on the two beams. A pyramidal-shaped seismic mass that gives a higher electric potential is realized by bulk micromachining using CMOS compatible 25 wt% tetramethyl ammonium hydroxide wet etching. The thickness of the beams is optimized using deep reactive-ion etching to achieve a low-frequency operation. COMSOL Multiphysics has been used to study the stress distribution to optimize the dimension and placement of the split electrodes. The optimized split electrodes give a reduced resonance frequency by 4.2% when compared with previously used electrode pattern ensuring maximum electric potential generation for guided two-beam structure. The resonance frequency of the device measured experimentally using laser Doppler vibrometer comes to be 466 Hz. The packaged device exhibits a maximum sensitivity of 1.5089 mV/m/s2 in the frequency range from 160 to 1000 Hz. [ABSTRACT FROM AUTHOR]

Studies have been taken into the breakdown voltage jitter of corona-stabilized switch at high repetition rate up to several kHz. It is thought that the gas recovery affect the jitter of breakdown voltage directly at high repetition rate, because the gas switch will breakdown at a low voltage if the gas cannot fully recover. The breakdown voltage jitter is called voltage jitter in the following paper. However, based on the experimental results, the voltage jitter still exists at low repetition rate, even at single-shot mode. This is not explained by the previous studies. In this paper, voltage jitter below 100 Hz of a corona-stabilized switch is investigated experimentally. A corona-stabilized switch is introduced, using a cylindrical electrode as the cathode and a plane electrode as the anode. The gas used between the electrodes is SF6. A negative pulse with a maximum width of 30~\mu \texts is used to charge this switch. The tested factors include gas pressure, gap space, repetition rate, and switch geometry. Experimental results show that voltage jitter is mainly affected by the gas pressure and switch geometry. It is seen that voltage jitter decreases as gas pressure increases and a suitable cathode geometry presents a low voltage jitter. Critical volume is a region close to the highly stressed electrode, where the presence of an electron will lead to an electron avalanche which attains a critical size and hence leads to a stabilizing corona. Critical volume is introduced to explain the experimental results. It is found that less voltage jitter can be achieved with a smaller and more concentrated critical volume, as well as efficient corona stabilization. The results indicate that voltage jitter may be reduced by optimize the critical volume at low repetition rate. [ABSTRACT FROM PUBLISHER]

Metallic joints are created in multivariable gas metal arc welding process by maintaining a balance between the quantum of heat generated and the feeding rate of electrode metal to the weld gap. The wire feeding control is often independently handled. The wire feeder unit should be simple, low cost, and capable of producing accurate speed. Arc welding controllers are often kept in clumsy conditions and the wire feeder unit is located close to the welder, could be much away from the controller. To reduce interconnections, separate sensing element for speed feedback should be avoided. Due to their negligible electrical and mechanical time constant, the pancake-type permanent magnet dc motor is suitable for wire feeding, where sensing of back electromotive force (EMF) for feedback is easy. When high frequency pulsewidth modulation (PWM) controller is used, the sensing of back EMF gets complicated. This paper explores the constraints on the choice of PWM frequency along with its maximum pulsewidth for different types of dc motors. It further elaborates comparatively on the choice of suitable control function for generating accurate speed control of wire feeding using back EMF as feedback. Finally, this paper also details the experimental results using the proposed control function. [ABSTRACT FROM AUTHOR]

This paper studies on the RF MEMS switch based on flexible liquid crystal polymer (LCP) substrate and the influence of the LCP substrate bending characteristics on mechanical properties of the switch. Due to the excellent properties of flexible LCP materials, RF MEMS devices based on LCP substrates will be very suitable for microwave systems with high space requirements and wearable devices. Obviously, the deformation of flexible substrate will affect the performance of RF MEMS switch. Therefore, this paper proposes a modeling of the substrate bending to analyze it. The experimental results of the fabricated switches show that the pull-in voltage of the switch is $\sim 22$ V, the insertion loss is better than −0.6 dB, the isolation is better than −15 dB, and the return loss is better than −18 dB up to 20 GHz. According to the experiments, we can find that when the curvature of the substrate is increased from zero to 22.2 (1/m), then the measured pull-in voltage is increased from 22.1 to 23.9 V and when the curvature of the substrate is increased from 22.2 to 44.2 (1/m), then the measured pull-in voltage is decreased from 23.9 to 18.9 V. In conclusion, with the increase of substrate curvature, the switch pull-in voltage will increase at first and then decrease. The experimental results are in good agreement with the modeling. [ABSTRACT FROM AUTHOR]

Papers, books, and standards consider the problem of mutual interactions of ground systems (GSs) by experimental data, parametric curves, mathematical approaches, and computer programs. This paper aims to analyze the physical phenomenon and basics, exemplifying the interference between GSs, such as their comparability, common intersection, mutual transfer resistance, and coupling factors. These characteristics assist to suppose the systems behavior in interaction and to suggest practical criteria for verifying the adequacy of GSs also versus the external interferences among them or/and with buried extraneous conductive part. The presence of a “global grounding system” (GGS) in the influence zone of a GS is a relevant case of interference. For definition, the GGS is not interfering, but can be locally interfered with unexpected increases of touch and step voltages. The global performance of an interfered GS can be defined by the overlap of two opposite and simultaneous behaviors: the passive and active behaviors, useful to characterize a GGS. In fact, a GGS essentially presents a passive behavior. [ABSTRACT FROM AUTHOR]

This paper presents an analysis of high-voltage direct current sea electrodes using different numerical techniques. The large volume of sea water that must be included in the analysis is represented using infinite (inclined layer model) and finite models (finite volume and hemispheroidal models). The comparison between the results obtained using these models is based on the potential rise of the electrode, the sea potential rise in the vicinity of the electrode, and the computational burden for utilizing each model. The analysis shows that the results obtained using finite models can predict the performance of the electrode more accurately and realistically. [ABSTRACT FROM PUBLISHER]

This paper suggests an advanced approach in the verification of the adequacy of a grounding system (GS) located in a common zone of influence with other GSs, taking into account the mutual interferences between the GSs. In fact, the presence of other GSs can transfer inadmissible touch and step voltages on the testing GS, particularly sensitive for critical power systems as data centers and hospitals. The safety of a local GS or of a global GS (GGS) does not admit uncontrolled interferences. Simulation programs assume a relevant importance, because they allow analyzing the interferences of GSs, particularly in operational difficulties for the tests. GSs have to maintain within the installation lifetime their characteristics of integrity and continuity and their safety performances; hence, they require a management program. This paper highlights the relevance of intrinsically safe GSs that guarantee safe touch/step voltages lower than permissible permanent voltages such as GGSs. GSs in city centers and urban and industrial areas evolve in time. Each installation of a new GS can influence the performance of the GSs existent in the area. Inspections and measurements are also necessary, following variations that can influence essential requirements. [ABSTRACT FROM AUTHOR]

The introduction of metal nanocrystals (NCs) has been confirmed to improve electrical uniformity of oxide-based resistive random access memory (RRAM) devices significantly; however, the current reports do not systematically elucidate the relationship between the size/distribution of NCs and the electrical uniformity of RRAM devices. In this paper, we focused on the impact of metal NCs size and areal density on the resistive switching (RS) performances of oxide RRAM by atomic layer deposition (ALD) based on the experimental results and theoretical calculation. The dependence of ALD cycles of 50–130 during Pt or CoPtx NCs growth on the RS parameters of Al2O3 or HfO2 memory units has been evaluated systematically. The RRAM embedded Pt or CoPtx NCs shows the trends: with increasing ALD cycles, the forming voltage, set/reset voltage, the resistance in off and on state, and ${R}_{ \mathrm{\scriptscriptstyle OFF}}/{R}_{ \mathrm{\scriptscriptstyle ON}}$ ratio entirely first decrease, then flatten, and increase later with a minimum value at about 100 cycles. Although all metal NCs with various sizes enhance the electric field strength compared to at the planar region, only metal NCs with proper NCs size and areal density (9 nm/6– $10\times 10^{\textsf {11}}$ /cm2 in this paper) can effectively produce stronger localized electric field at the tip of metal NCs, leading to optimal RS behavior. [ABSTRACT FROM AUTHOR]

When developing silicon carbide (SiC) devices, the reliability of the internal body diode is an important issue. Stacking faults (SFs) are expanded from basal plane defects by using a body diode. Although it is well known that ON-voltage degradation occurs due to SFs, their effects on dynamic reliability have not been studied well. Furthermore, including the effects of SFs, there are not many reports about the dynamic reliability of SiC-MOSFETs. In this paper, a double-pulse switching test using 3.3-kV SiC-MOSFETs was carried out to clarify the failure mechanism of the switching operation of SiC-MOSFETs and effects of SFs on the safe operation area (SOA). Before the switching test, current stress was applied to the body diode of the devices under test (DUTs) to expand the SFs. The circuit configuration was half-bridge type, and a double-pulse gate signal was applied to the lower arm DUT. The switching voltage was 1.8 kV, and the switching current increased at about 8-A steps to failure. As a result, reverse recovery SOA (RRSOA) reliability decreased depending on the amount of SFs in the SiC-MOSFET. Because RRSOA failure was caused by avalanche due to the hole concentration during reverse recovery and the SFs raised local current density, reverse bias SOA (RBSOA) hardly decreased even if SFs containing SiC-MOSFETs were used. This is because RBSOA failure was caused by degradation of the gate isolation layer due to overheating and the temperature coefficient of the SFs electric resistance indicated negative. [ABSTRACT FROM AUTHOR]

In this paper, we demonstrate the linear conductance-change characteristics of a conductive-bridging RAM (CBRAM) to be employed as an artificial synapse device in neuromorphic systems. The CBRAM with a bilayer electrolyte structure (${\mathrm {Cu/Cu}}_{{2}-{x}}\text{S}$ / $\mathrm {WO}_{{3}-{x}}$ /W) exhibits analog switching behavior during the depression process due to the well-controlled dissolution of the conductive filament. To analyze the origin of this motion, we investigate the effective voltage applied to $\mathrm {Cu}_{{2}-{x}}\text{S}$ and $\mathrm {WO}_{{3}-{x}}$. Our findings reveal that $\mathrm {Cu}_{{2}-{x}}\text{S}$ , acting as a voltage divider, helps in suppressing the large voltage drop in $\mathrm {WO}_{{3}-{x}}$ , where the formation/dissolution of filament occurs. Furthermore, due to the diode-like characteristics of $\mathrm {Cu}_{{2}-{x}}\text{S}$ and the division of voltage drop between $\mathrm {WO}_{{3}-{x}}$ and $\mathrm {Cu}_{{2}-{x}}\text{S}$ , an optimum programming energy is applied to $\mathrm {WO}_{{3}-{x}}$ during the depression process. This leads to linear conductance-change characteristics under identical pulses. However, abrupt conductance-change characteristics are observed during the potentiation process. Thus, we use only the device characteristics of the depression part for the neuromorphic system. An excellent classification accuracy is achieved due to the linear conductance-change characteristics and optimized pulse conditions. [ABSTRACT FROM AUTHOR]

An innovative approach has been recently proposed for the voltage breakdown prediction in high-voltage systems, insulated by large vacuum gaps. This approach is based on complementary geometric formulations for electrostatics coupled to the analytical solution of the equations of motion for charged particles. In this paper, a goal-oriented local mesh refinement technique is introduced, which allows to increase the rate of convergence of the solution, enabling an effective voltage breakdown prediction also in large-scale systems with complex geometries. [ABSTRACT FROM AUTHOR]

Converter transformers in HVDC system use oil-pressboard as the main insulation. The insulation structures of valve side need to withstand combined AC-DC voltage. Oil-pressboard insulation shows distinctive PD characteristics under combined AC-DC voltage which are the bases of insulation assessment and fault diagnosis. In this paper, PD characteristics are investigated with the established experimental platform of ballplate electrode under 1:1 combined AC-DC voltage. The behavior of experimental results is explained trough discharge mechanism. To reflect the characteristics of the whole PD development process without the influence of test conditions on PD magnitude, Φ-ΔT-N pattern is used to establish the 3D spectrum Hn (ΔT,Φ) based on time interval, phase and repetition rate of PD pulses. Barycenter C (xc, yc) is calculated as a comprehensive feature parameter. In order to exclude the effect of oscillation components on real-time assessment, variational mode decomposition (VMD) is used to extract the primary development trend of the feature parameter. The difference value R (X, Y) between the value of each point in the trend and the reference target decreases in the whole PD development process. And R can assess the PD development degree continuously based on the historical trend without the normalization problem of PD magnitude. [ABSTRACT FROM AUTHOR]

A comprehensive study is conducted on the electron transport in conductive polymer matrix composites (CPMCs), employing the nonequilibrium Green’s function formalism. This paper provides a microscopic insight into the electron tunneling through the potential barriers existing between conducting sites. It is shown that Wentzel–Kramers–Brillouin approximation as well as other models with simple barrier shapes, which are widely used in literature, can lead to inaccurate results in comparison with the quantum mechanical approach using a hyperbolic barrier. In this paper, unlike most previous ones, percolation-related effects are disregarded for further focus on electron transport through the polymer potential barriers. It is assumed that a tunneling-conductive channel exists between the electrodes. This can be created either by applying electric field alignment or using a filler volume fraction higher than the percolation threshold. A two electrode resistive device is studied and the results indicate that a conductor–insulator transition occurs at a barrier thickness of $\sim 1.7$ nm and the barrier thickness should be larger than several angstroms. Next, a novel tunneling field-effect structure based on CPMCs is introduced and its characteristics are comprehensively investigated. This device features a remarkably simple structure, an extremely high channel to gate coupling, a large transconductance, and a high current level. Besides, it has the advantage of being based on polymers. This ensures favorable physical properties, ease of fabrication, and low-cost processing techniques. [ABSTRACT FROM AUTHOR]

This paper addresses the numerical investigation of an electrohydrodynamic (EHD) plume induced by a sharp blade electrode in a dielectric liquid. Different injection laws, namely, autonomous and nonautonomous ones, are considered, and the importance of the blade shape is emphasized, especially for nonautonomous injection laws. Different flow regimes arise according to the value of the Reynolds number based on the ionic mobility and the distance $d$ between the blade and the vertical plate. It is found that the critical Reynolds number for which the transition between steady and unsteady regimes occurs depends on the injection law, on the blade shape, on the $M$ parameter, and on the injection strength $C$. For much higher Reynolds number, the flow turns to be chaotic and behaves as a jet flow with the development of a Kelvin–Helmoltz instability. The use of different sharp blades indicates that a higher electric field at the tip of the blade plays a significant effect on the development of the EHD plume. The plumes have been characterized by their charge density distribution which shows, in the early stages of the simulation, that its dynamics is significantly dependent on the blade shape as well as on the nonautonomous injection law. [ABSTRACT FROM AUTHOR]

Temperature field simulation for self-healing power capacitor makes sense to the capacitor optimization and improvement of capacitor’s rated voltage and capacity. On the basis of reasonable simplifications and assumptions for capacitor structure, a 3-D temperature field numerical simulation model for a self-healing power capacitor is formulated in Fluent 15.0. The ambient temperature is set to 55 °C, and the applied voltage is ac 400 V. The temperature distributions of the shell and core of the self-healing capacitor are obtained. The results reveal that the temperature of the core is 2 °C–3 °C higher than that of the shell. The highest temperature of the shell locates on the large side surface, and the temperature of the large side surface is higher than that of the small side surface. To validate the above simulation, a self-healing capacitor is manufactured and thermal resistance sensors are used to measure the temperature in the thermal stability test. The simulation is validated by the experiment. Finally, the influences of the ambient temperature and applied voltage on the temperature rise are investigated. This paper can be taken a reference to the self-healing capacitor operation, maintenance, and even the optimization of its internal structure and material. [ABSTRACT FROM PUBLISHER]

This paper proposes a coupled analysis method to deal with ion generation and ion drift in the air. Electric discharge is utilized in various products, and it is very important to clarify not only how much ion is generated but also where ion drifts in the air. The proposed method, which modeled interactions between electric field and ion behavior, including ion generation, ion drift, and charging of a dielectric body, has succeeded in calculating charge removal of a metallic target, which was tens of millimeters away from a pin electrode as a source of generated ion. The calculated results show that the amount of generated ion is drastically changed because electric field is affected by electric charge of ion in the air and charging of a dielectric body. This paper also reports a comparison of measured and calculated results of charge removal time of a metallic target, which were found to be in good agreement. [ABSTRACT FROM AUTHOR]

In this paper, a lithium ion cobalt polymer battery cell is modeled using 3-D finite elements (3DFE) for the study of its performance under a wide range of operating scenarios. The electrochemistry is modeled and coupled to an electromagnetic model to forecast the cell voltage overpotential as a result of charging and discharging under six current densities. To study this phenomenon, light ( $C$ /10), medium ( $C$ /2), and high ( $1C$ ) charging and discharging currents are imposed at the battery terminals and compared with experimental results. The electric field inside the electrodes and electrolyte is analyzed at each case highlighting regions where loss occurs. A magnetic field analysis depicts the total electrochemical generation of current densities inside the cell while identifying how the development of gradient currents occur, a mechanism which can shorten the life span of the battery. This paper distinguishes where 3DFE analysis battery models can be useful in studying how lithium ion batteries will behave given a particular loading or a charging profile before placing them in service. [ABSTRACT FROM AUTHOR]

To prevent the high voltage direct current ground electrode from eroding, it is usually wrapped by a coke bed, which may affect the electrical performance of the electrode, such as current distribution and step voltage. In this paper, the effect is analyzed by a numerical method, which couples moment method with circuit theory by regarding the coke bed as several resistors connecting the ground electrode with soil. The method is simple and efficient. The calculated results are in good agreement with the measured ones. The current distribution, ground resistance. and step voltage of several typical electrodes with and without coke beds are calculated. The effect of the coke bed on the above parameters is summed up. [ABSTRACT FROM AUTHOR]

The design and development of a new nonintrusive-type true-rms ac voltage measurement probe are presented in this paper. The measurement circuit of the capacitively coupled nonintrusive voltage sensor is designed to provide an output that is directly proportional to the rms value of unknown ac voltage $\text{V}_{\mathrm {X}}$ , which contains the power frequency (50 or 60 Hz) component along with the typical harmonic frequency components due to nonlinear loads. This is accomplished by a specially designed autobalancing signal conditioning circuit. The existing noncontact probes are designed for a set frequency and will not provide accurate rms value of a signal that has multiple frequency components. The output is independent of the coupling capacitance between the probe electrode and the insulated wire/cable under measurement. Thus, the sensor has low sensitivity to the variation due to the probe-to-wire capacitance, good linearity (0.95%), and accuracy (0.88%) over a range of voltages (0–1000 V) tested. Various parameters that affect the performance of the probe are analyzed, quantified, and discussed in this paper. A prototype of the probe along with the proposed autobalancing circuit has been designed and developed. The prototype has been tested in detail to evaluate the accuracy, linearity, and repeatability. The results obtained established the practicality of the proposed scheme. [ABSTRACT FROM AUTHOR]

This paper investigates the dependence of the supercapacitor Peukert constant on its terminal voltage, aging condition, and operating temperature. Recent studies show that the charge delivered by a supercapacitor during a constant current discharge process increases when the discharge current decreases if the discharge current is above a certain threshold, i.e., Peukert's law applies. By conducting extensive experiments using three supercapacitor samples with different rated capacitances from different manufacturers, this paper reveals that the Peukert constant increases when the initial voltage of the constant current discharge process is lower, the supercapacitor is more heavily aged, or the operating temperature is lower. The physical mechanisms accounting for the Peukert constant dependence are illustrated by analyzing an $RC$ ladder circuit model. When the supercapacitor terminal voltage is higher, the aging condition is lighter, or the operating temperature is higher, more charge is stored in the supercapacitor. Consequently, when the same discharge current is applied, the discharge time is longer and the branch capacitors are more deeply discharged. Therefore, the relaxation effects of the slow branches are reduced and the supercapacitor behaves more like a single capacitor rather than a distributed capacitor network, which ultimately leads to a lower Peukert constant. [ABSTRACT FROM AUTHOR]

In this paper, a microfluidic device is introduced based on direct current (dc) dielectrophoresis for the separation of circulating tumor cells from normal blood cells. Differential sidewall electrodes are designed inside the channel and two middle-channel outlets are located after the end of the electrodes, which are assigned to collect the normal blood cells. A maximum dc potential of 3 V is applied to the electrodes, resulting in a differential dielectrophoretic forces acting on the cells. This paper involves isolating MCF-7 breast cancer cells from white blood cells (WBCs) and red blood cells (RBCs), eliminating the demand for primary RBC lysis. Numerical simulation results revealed that the differential electrodes not only suppressed successfully the need for high applied voltages by dc dielectrophoresis but also diminished the joule heating effects. Besides that, the arrangement of the differential electrodes was observed to play a critical role in the separation performance. In particular, designing the outlets, as well as adjusting the electrode potentials, has effectively assisted the device to be tunable for different cancer cells even with different radii. More strikingly, the ability of the device to deflect the waste cells (WBCs and RBCs) to out of the microchannel prior to the cancer cells was proven to positively affect the separation efficiency and purity. The proposed device was capable of separating different cells leveraging various diameters with capture purity and efficiency of higher than 83% and 100%, respectively. [ABSTRACT FROM AUTHOR]

Surface charge accumulation on polymer insulating material has been recognized as an important factor for electric field distortion that results in reduction of surface flashover voltage. This paper reports on the charge accumulation behavior between a pair of finger-shaped electrodes on epoxy/Al2O3 nanocomposites under dc voltage superimposed by repetitive pulses. The charge distribution was measured by means of an electrostatic voltmeter, from which the average charge density could be calculated. Effects of dc voltage, nanofiller content, and pulse voltage on charge accumulation behavior were investigated. Obtained results showed that with the increase in the filler content from 0 wt% to 5 wt%, the average charge density increased initially then appeared to decrease. The superposition of repetitive pulses on dc voltage led to a remarkable growth in charge accumulation as compared with that when only dc voltage was applied. It is suggested that the charges are originated from local gaseous ionization and/or electrode injection, which is determined by the combined voltage. The charge density is dependent upon the surface trap, which is affected by nanofiller content. The superposition of repetitive pulse is considered as a possible reason to encourage local gaseous ionization that results in enhanced accumulation of surface charge. [ABSTRACT FROM AUTHOR]

The multigap gas switch has been widely used in liner transformer drivers (LTDs), but there is still room for improvement on its self-breakdown and triggering characteristics. In this paper, based on the circuit model of the six-gap gas switch, the gap voltage distribution during the charging and triggering process is analyzed, and the optimization on self-breakdown and triggering characteristics by mounting resistors and capacitors in parallel with switch gaps are theoretically and experimentally investigated. The results indicate that compared with the original switch, when the self-breakdown voltage is about ±90 kV, the standard deviation is reduced from 7.5 to less than 3 kV; for a charging voltage of ±80 kV and by operating at 60% working coefficient, when the negative trigger voltage is 75 kV, the jitter of the switch is reduced from 6.1 to 1.4 ns. [ABSTRACT FROM AUTHOR]

In this paper, a super-junction p-type lateral diffused metal–oxide–semiconductor transistor (SJ-pLDMOS) utilizing electron to enhance the current capability is proposed. The proposed SJ-pLDMOS has an n-channel in the drain region and is controlled by an auto-generated voltage signal (${V}_{\mathrm {\textsf {Gn}}}$). The voltage signal ${V}_{\mathrm {\textsf {Gn}}}$ is generated during the ON- and OFF-state of the hole current which flows across an integrated resistor (${R}\text{p}$) implemented in the p-base region. Thus, the proposed SJ-pLDMOS utilizes both hole and electron currents to significantly enhance the current capability. Simulation results show that the current capability of the proposed SJ-pLDMOS without any conductivity modulation effect is comparable with that of a super-junction nLDMOS (SJ-nLDMOS). The total power loss of the proposed super-junction pLDMOS (SJ-pLDMOS) is reduced by about 26.7% and 18% compared with that of the SJ-nLDMOS and Triple Resurf nLDMOS (TR nLDMOS) at a rated load current density of $25~\mu \text{A}/\mu \text{m}$ , respectively. [ABSTRACT FROM AUTHOR]

Due to its low-loss and high dielectric strength, polypropylene is widely used as electrical insulation material in pulse capacitors. In order to study its breakdown characteristics for nanosecond voltage pulses, an experimental setup was designed to generate voltage pulses with a 10%–90% rise time of 38 ns and a full width at half maximum of about 90 ns. Tests of the three polypropylene films with thicknesses of 12, 15, and $18~\mu \text{m}$ were performed. In addition, hundreds of nanoseconds pulse and dc voltage were also applied for comparison. The experimental results reveal that most of the breakdown occurs during the front edge of the pulse for tens of nanoseconds pulse, and the breakdown strengths of the three kinds of polypropylene films are almost identical for different applied voltages, which show a weak correlation between the thickness of the dielectric and the breakdown field. The expected breakdown strength of tens of nanoseconds pulse defined in this paper is not significantly higher than the mean value of the hundreds of nanoseconds pulse and the dc condition, suggesting that the breakdown of a thin polypropylene film is mainly determined by the electrical field but not the voltage-time cumulative effect. All these observations strengthen the conclusion that the breakdown of a thin polypropylene film is an intrinsic phenomenon. [ABSTRACT FROM AUTHOR]

Since there exist discharge problems in gas insulated metal-enclosed switchgear due to internal metal particle movement, the study in this paper thus, conducted an experiment and simulation research on the movement characteristics of particles, where the charge on particle and the collision recovery coefficient (CRC) was obtained. When the electrode is brass, the charge on the particle is close to the theory one and the CRC of aluminum, stainless steel and particle are 0.52, 0.75 and 0.79 respectively. Accordingly, the study, in order to take the particle charge and its collision process into consideration, established a particle movement model, and conducted a test has thereof. The results show that there exists excellent consistency between charge and its collision. According to the research, the relationship between particle size, material and collision characteristics was revealed. The result shows that under DC voltage the metal particle collision frequency decreases with the increase of particle size when the material of the particles is the same. The time difference between particles' moving to high voltage electrode and ground electrode becomes greater with the increase of the size of the particle. When the particle material is different, the collision characteristics are influenced by its density and collision recovery coefficient of restitution. Particle motion velocity loss becomes less before and after the collision when its collision recovery coefficient of restitution is larger. So the collision frequency is higher. The research results in this paper can offer some reference value to particles suppression measures in gas insulated metal-enclosed transmission line. [ABSTRACT FROM PUBLISHER]

The International Electrotechnical Commission Standard 61936-1 “Power installations exceeding 1 kV a.c.” defines the “global grounding system” (GGS) as an equivalent grounding system that ensures “no dangerous touch voltages.” This paper deals with an analysis of the parameters that characterize the behavior of grounding systems (GSs) operating in the same zone of influence (ZOI) and proposes to recognize four levels of “globality.” With this aim, the geometric criterion and the safety criterion are introduced to identify the ZOI. The safety criterion allows for identifying a GGS and characterizing the global ZOI of a GGS. This paper highlights the relevance of recognizing what is intrinsically safe for a GS that guarantees safe touch/step voltages lower than permissible permanent voltages. An integration of many coexisting GSs for constitution and extension, naturally, can reach the level of an intrinsically safe GS and, hence, of a GGS. [ABSTRACT FROM AUTHOR]

Grounding is essential to build effective lightning protection design for electric power equipment. The main role of grounding is to disperse abnormal current such as that from lightning into the soil via a grounding electrode. When the lightning current flows into the grounding electrode, the electrical potential of the electrode rises, and overvoltage arises between the equipment connected to the grounding electrode and nearby equipment. The overvoltage causes equipment to breakdown or malfunction. An effective grounding electrode controls the overvoltage at the equipment in a lightning strike and can ensure the normal operation of electrical equipment. The most common grounding electrodes are the vertical grounding rod and the horizontal buried electrode. A property of these grounding electrodes, known as effective length, has been investigated by many researchers. Many formulas to express effective length have already been proposed, all of which are determined heuristically on the basis of formulas that approximate the property from experimental or analytical test results; they are not formulas derived based on the physical phenomenon of grounding. In this paper, we first report on the results of the derivation of a formula for effective length based on the propagation velocity within the soil and the depth of penetration of the lightning surge into the soil. The aforementioned formula still has unknown constants. To decide those parameters, the finite-difference time-domain method is utilized. [ABSTRACT FROM PUBLISHER]

Repetitive high-voltage square pulses are of great importance for producing long-pulse electron beams and high-power microwaves. One of possible technologies for the generation of such pulses is a Marx generator using pulse forming network (PFN) stages, often combined with a pulse sharpening technique to reduce the rise time to a few nanoseconds (peaking stage). This paper presents an innovative design, named the “zigzag design,” for the optimization of the compactness and of the rise time of 400-kV–85-ns PFN-Marx. Thanks to this design, the 16 stages of this generator, which delivers an open circuit output voltage of 720 kV, fit in a 650-mm length. For a slightly overmatched load ($Z_{\mathrm {load}} = 100 ~\Omega$), the output voltage reaches 400 kV with a rise time as less as 5 ns. The inductance reduction associated with the innovative zigzag design, which allows this sharp rise time with no need for a peaking stage, is described. The 85-ns plateau duration of the pulse is given by the PFN construction of each stage, which is based on six ceramic capacitors (2.1 nF–45 kV) connected within a strip line. The 16 PFN stages are housed in a 360-mm diameter gas pressurized vessel. Burst mode operation for a duration of 10 s at a pulse repetition frequency of 100 Hz is reported, for a resistive load and for the electron beam diode of a X-band relativistic backward-wave oscillator (BWO). To reach further compactness, the BWO system is integrated on side of the generator vessel and a U-shaped gas pressurized line connects both systems through a compact conical vacuum insulator. [ABSTRACT FROM AUTHOR]

The basic structure and work mechanism of laser-triggered vacuum switch (LTVS) are introduced briefly in this paper, and the processes of primary plasma production and expansion are analyzed as well. A series of experiments has been carried out with different gap voltages, laser wavelengths, laser energies, polarity configuration modes, switch structures, focal lengths, and laser waveforms. The switch structure is modified to improve the heavy-current capability of the switch, and the gap distance is increased to improve the voltage capacity. The special design of the trigger structure can reduce the dependence on the laser energy of the switch and the time delay. A new laser waveform of LTVS multiple wave crests could further decrease the laser energy, and it is the research basis of laser trigger miniaturization and its application in the LTVS. [ABSTRACT FROM PUBLISHER]

This paper presents an experimental investigation of the turn-ON of nanoscale T-RAM cells under the transient conditions given by the depletion of the $p$ -base from holes. Data reveal that hole depletion increases the dynamic turn-ON voltage of the device for a stretch of time depending on the gate and anode bias during the hold phase and on the gate voltage used for device sensing. The results are explained considering that the gate and anode biases during hold affect the rate of hole generation bringing the device back to its equilibrium condition, while the gate voltage applied to sense the state of the gated-thyristor determines the $p$ -base potential and, therefore, the amount of holes in the $p$ -base required to turn the device on. [ABSTRACT FROM AUTHOR]

In this paper, a method is developed to optimize the geometry and to improve the sensitivity of four-terminal planar Hall devices under the voltage biasing. Using the conformal mapping, we can construct geometrically different Hall devices with the same sensitivity. The Hall voltage sensitivities thus obtained are close to the theoretical limit. Our analysis is verified by a recent experiment on graphene Hall devices, as well as previous theoretical works. [ABSTRACT FROM AUTHOR]

In this paper, we propose a novel, low-cost, and universal tactile sensing technology for imaging pressure distribution using a tomographic approach with conductors. In particular, we focus on the fact that pressure is related to the contact resistance between two conductive objects. The sensor comprises driving and probing conductors, which are electromechanically coupled. The system solves an inverse problem for estimating electrical boundary conditions using the voltage sets from electrodes on the border of the probing conductor. The sensing system successfully estimates the pressure distribution, contact location (error rate: 5.68 $\pm$ 2.78%), and local pressure (error in the range 0.0269 $ -$ 0.0509 N/mm $^2$ for a maximum pressure of 0.50 N/mm $^2$). Finally, tactile imaging by sheet- and finger-type sensors are demonstrated as practical applications of the developed sensor. [ABSTRACT FROM AUTHOR]

To meet the great need for distributed and sustainable power sources, mechanical energy in the environment is widely used for electricity generation. Based on the coupling effect of triboelectrification and electrostatic induction, triboelectric nanogenerator (TENG) as an innovative energy technology has advantages of collecting fluctuating amplitude and low-frequency mechanical energy. In this paper, a leaf-shaped TENG has been demonstrated to harvest multiple ambient mechanical energy. By the characterization with different mechanical energy sources, the leaf-shaped TENG has been proven as an effective tool to scavenge wind, vibration, and falling raindrop energy. Furthermore, based on numerous leaf-shaped TENGs, a leaf-shaped TENG tree has been developed, which can be used for continuous collection of environmental mechanical energy at large-scale. This paper has first exhibited a conformal structure for simultaneously harvesting various mechanical energy, which has bright potentials in environmental monitoring, Internet of things, and wireless sensor networks. [ABSTRACT FROM AUTHOR]

Knowledge of the performance of microbial electrolysis cells under a wide range of operating conditions is crucial to achieve high production efficiencies. Characterizing this performance in an experiment, however, is challenging due to either the long measurement times of steady-state procedures or the transient errors of dynamic procedures. Moreover, wide parallelization of the measurements is not feasible due to the high measurement equipment cost per channel. Hence, to speedup this characterization and to facilitate low-cost, yet widely parallel measurements, this paper presents a novel rapid polarization curve measurement procedure with a dynamic measurement resolution that runs on a custom six-channel potentiostat with a current-driven topology. As case study, the procedure is used to rapidly assess the impact of altering pH values on a microbial electrolysis cell that produces H2. A $\times 2$ – $\times 12$ speedup could be obtained in comparison with the state-of-the-art, depending on the characterization resolution (16–128 levels). On top of this speedup, measurements can be parallelized up to $6\times $ on the presented, affordable—42$-per-channel—potentiostat. [ABSTRACT FROM AUTHOR]

The dc current injected into the earth from the grounding electrodes of an HVdc system could flow into the ac electric power grids and gas pipelines through their grounding points. The dc current distribution either in ac power grids or in pipelines would be affected by each other. In this paper, a numerical approach to simulate the dc current distribution in ac power grids and gas pipelines considering the interaction is put forward. The approach is validated by field test. The dc current distribution in ac power grids and gas pipelines is discussed based on the calculation result in a real case. It is found that the effect of ac power grids on the current distribution in gas pipelines is greater than the effect of gas pipelines on the current distribution in ac power grids. [ABSTRACT FROM AUTHOR]

Electroencephalogram (EEG) electrodes are critical devices for brain-computer interface and neurofeedback. A pre-gelled (PreG) electrode was developed in this paper for EEG signal acquisition with a short installation time and good comfort. A hydrogel probe was placed in advance on the Ag/AgCl electrode before wearing the EEG headband instead of a time-consuming gel injection after wearing the headband. The impedance characteristics were compared between the PreG electrode and the wet electrode. The PreG electrode and the wet electrode performed the Brain-Computer Interface (BCI) application experiment to evaluate their performance. The average impedance of the PreG electrode can be decreased to 43 $\text{k}\Omega $ or even lower, which is higher than the wet electrode with an impedance of 8 $\text{k}\Omega $. However, there is no significant difference in classification accuracy and information transmission rate (ITR) between the PreG electrode and the wet electrode in a 40 target BCI system based on Steady State Visually Evoked Potential (SSVEP). This study validated the efficiency of the proposed PreG electrode in the SSVEP-based BCI. The proposed PreG electrode will be an excellent substitute for wet electrodes in an actual application with convenience and good comfort. [ABSTRACT FROM AUTHOR]

This paper proposes a self-sensing measurement technique to perform the precise estimation of the displacements along two axes in a two-degrees-of-freedom (2-DOF) piezoelectric actuator. For that, a new electrical circuit scheme that permits charge amplification is first proposed to match the different electrodes combination of the 2-DOF actuator. Then, a new bivariable observer that precisely estimates the displacements is calculated and implemented experimentally in a cascade with the electrical circuit to complete the self-sensing. The experimental tests and results verification with external sensors revealed that the measured displacements given by the developed self-sensing measurement technique derive better than a micron of precision which well fits to micromanipulation applications. Discussion about the features and the performances improvement perspectives of the suggested approach are presented at the end of the paper. [ABSTRACT FROM AUTHOR]

An amorphous indium–tin–zinc-oxide thin-film transistor (a-ITZO TFT)-based voltage-mode active pixel sensor (V-APS) is discussed, for the first time, in this paper. The a-ITZO TFT shows superior electrical characteristics, including a high field-effect mobility ( \mu \mathrm {\mathbf {EFF}} > 30 cm2/ \text V\cdot \text s ), a steep subthreshold slope (SS < 200 mV/decade), and a low OFF-current ( I\mathrm{\scriptscriptstyle OFF} < 10^{-14} A), that are suitable for applications such as X-ray imagers. The proposed V-APS is based on the top-illuminated organic photodiode (OPD) or amorphous silicon p+-i-n+ photodiode (a-Si p+-i-n+ PD). Simulation results indicate that, in contrast with common source V-APS, source follower (SF) V-APS is more desirable for X-ray imagers due to its better linearity property. The OPD or the a-Si p+-i-n+ PD does not affect the voltage gain of SF V-APS. But the PDs have different influences on charge-to-voltage conversion gain. The impact of PD capacitances and dark saturation currents on detectable quantities of electrons is also investigated. The influence of the TFT threshold voltage shift on circuit performance, sensitivity, and noise analysis of SF V-APS is discussed. [ABSTRACT FROM PUBLISHER]

In this paper, we propose a novel conductance parallel-wire array probe (CPAP) to measure the interface characteristics of segregated horizontal oil–water two-phase flows. A measurement system of CPAP is designed to make it work in a cyclic excitation mode and detect the interfacial heights at different locations of a pipe cross section. A finite-element analysis and a static calibration experiment are conducted to access the relationship between the interfacial height and the dimension conductance detected by the CPAP. Through carrying out a dynamic experiment of horizontal oil–water flows, the 3-D oil–water interfaces are reconstructed using the CPAP responses to study the interfacial evolution and its effect on the droplet detachment. Finally, the average fluctuations of the oil–water interfaces are extracted based on the reconstructed 3-D oil–water interface. [ABSTRACT FROM AUTHOR]