Average Electric Field Research Articles

Analysis of a hollow piezoelectric semiconductor composite cylinder under a thermal loading

Piezoelectric semiconductors (PSs) are the most promising building blocks for multifunctional electronic devices due to the polarization field resulting from piezoelectricity and pyroelectricity. In this article, we investigate the electromechanical coupling behaviors of a hollow PS composite (HPSC) cylinder under a uniform temperate change. The HPSC cylinder is consist of an outer thin PS layer and an inner elastic layer. Taking the interactions of thermoelasticity, piezoelectricity, and pyroelectricity into account, we develop one-dimensional equations for the HPSC cylinder with axisymmetric deformation, and present analytical solutions of the physical fields in the HPSC cylinder with perfect and imperfect interfaces for different boundary conditions. For the static equilibrium equation of the PS layer, the approximate relationship between the electric field and the average electric field is employed. The effects of geometrical parameters and imperfect interface, as well as the tuning effect of thermal loadings, on the multifield coupling responses and piezotronic effects of the HPSC cylinder are discussed in detail. The numerical results show that the physical fields are sensitive to the thermal loading, and the geometrical parameters, boundary conditions, and the interface bonding condition play an important role in the design of PS devices.

First principles study of field effect device through van der Waals and lateral heterostructures of graphene, phosphorene and graphane

Chemical modification and vertical stacking of two-dimensional materials are promising techniques for new nanoelectronic devices. We present Density Functional Tight Binding (DFTB) calculations of a field-effect device, based on lateral and vertical heterostructures of 2D materials. The device consists of a phosphorene channel protected by graphene sheets, which work as contacts and are divided into the source and drain by local hydrogenation of graphene, which gives insulating graphane. In this device composed of only 3 layers, single sheets of graphene-graphane can work as both leads and oxide gate, while also acting as protective layers for a phosphorene channel. We show how for perfect vdW heterostructures of graphane/phosphorene/graphane and graphene/phosphorene/graphene the Schottky barrier is deeply influenced by normal electric fields, and we characterize electronic transport of such a device. Finally, we characterize phosphorene channel doping and defects, which, at very high densities in the transport direction, enables transport inside the phosphorene bandgap.

Edge modes and their conductance in narrow nanoribbons of 2D materials in a topological phase

Employing novel 2D materials with topologically protected current-carrying edge states is promising to boost the on-current in electronic devices. Using nanoribbons is essential to reduce the contribution of the 2D bulk states to the current. Making the nanoribbon widths narrower allows one to put more current-carrying edge states under the gate of a fixed width thus increasing the current. However, the edge states from opposite edges may start to interact in narrow nanoribbons. Based on an effective k∙p model, we analyze the topologically protected edge states and their conductance for several 2D materials as a function of the normal electric field. We compare the 2D materials MoS2, MoSe2, WS2, and WSe2 in the topological 1T′ phase and find the largest electric field-induced conductance modulation in MoS2 nanoribbons.

Neurocapillary-Modulation

ObjectivesWe consider two consequences of brain capillary ultrastructure in neuromodulation. First, blood-brain barrier (BBB) polarization as a consequence of current crossing between interstitial space and the blood. Second, interstitial current flow distortion around capillaries impacting neuronal stimulation. Materials and MethodsWe developed computational models of BBB ultrastructure morphologies to first assess electric field amplification at the BBB (principle 1) and neuron polarization amplification by the presence of capillaries (principle 2). We adapt neuron cable theory to develop an analytical solution for maximum BBB polarization sensitivity. ResultsElectrical current crosses between the brain parenchyma (interstitial space) and capillaries, producing BBB electric fields (EBBB) that are >400x of the average parenchyma electric field (ĒBRAIN), which in turn modulates transport across the BBB. Specifically, for a BBB space constant (λBBB) and wall thickness (dth-BBB), the analytical solution for maximal BBB electric field (EABBB) is given as: (ĒBRAIN × λBBB)/dth-BBB. Electrical current in the brain parenchyma is distorted around brain capillaries, amplifying neuronal polarization. Specifically, capillary ultrastructure produces ∼50% modulation of the ĒBRAIN over the ∼40 μm inter-capillary distance. The divergence of EBRAIN (Activating function) is thus ∼100 kV/m2 per unit ĒBRAIN. ConclusionsBBB stimulation by principle 1 suggests novel therapeutic strategies such as boosting metabolic capacity or interstitial fluid clearance. Whereas the spatial profile of EBRAIN is traditionally assumed to depend only on macroscopic anatomy, principle 2 suggests a central role for local capillary ultrastructure—which impact forms of neuromodulation including deep brain stimulation (DBS), spinal cord stimulation (SCS), transcranial magnetic stimulation (TMS), electroconvulsive therapy (ECT), and transcranial electrical stimulation (tES)/transcranial direct current stimulation (tDCS).

Electric Field Strength From Prefrontal Transcranial Direct Current Stimulation Determines Degree of Working Memory Response: A Potential Application of Reverse-Calculation Modeling?

BackgroundTranscranial direct current stimulation (tDCS) for working memory is an enticing treatment, but there is mixed evidence to date. ObjectivesWe tested the effects of electric field strength from uniform 2 mA dosing on working memory change from prestimulation to poststimulation. Second, we statistically evaluated a reverse-calculation method of individualizing tDCS dose and its effect on normalizing electric field at the cortex. Materials and MethodsWe performed electric field modeling on a data set of 28 healthy older adults (15 women, mean age = 73.7, SD = 7.3) who received ten sessions of active 2 mA tDCS (N = 14) or sham tDCS (N = 14) applied over bilateral dorsolateral prefrontal cortices (DLPFC) in a triple-blind design. We evaluated the relationship between electric field strength and working memory change on an N-back task in conditions of above-median, high electric field from active 2 mA (N = 7), below-median, low electric field from active 2 mA (N = 7), and sham (N = 14) at regions of interest (ROI) at the left and right DLPFC. We then determined the individualized reverse-calculation dose to produce the group average electric field and measured the electric field variance between uniform 2 mA doses vs individualized reverse-calculation doses at the same ROIs. ResultsWorking memory improvements from pre- to post-tDCS were significant for the above-median electric field from active 2 mA condition at the left DLPFC (mixed ANOVA, p = 0.013). Furthermore, reverse-calculation modeling significantly reduced electric field variance at both ROIs (Levene's test; p < 0.001). ConclusionsHigher electric fields at the left DLPFC from uniform 2 mA doses appear to drive working memory improvements from tDCS. Individualized doses from reverse-calculation modeling significantly reduce electric field variance at the cortex. Taken together, using reverse-calculation modeling to produce the same, high electric fields at the cortex across participants may produce more effective future tDCS treatments for working memory.

A 2.2kV Organic Semiconductor- Based Lateral Power Device

The application of organic field-effect transistors (OFETs) in the power device realm has not been explored yet. To achieve a high breakdown voltage, a novel lateral drift region OFET(LDR-OFET) is proposed in this letter. By employing the diketopyrrolopyrrole-based polymer(DPPT-TT) and Poly (methyl methacrylate) (PMMA) to form semiconductor and insulator layers respectively, the fabricated LDR-OFET, despite the simple process and low cost, exhibits an excellent off-state breakdown capability while maintaining a considerable on-state performance. With a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$20~\mu \text{m}$ </tex-math></inline-formula> length of the drift region, the LDR-OFET realizes 2200V breakdown voltage on a spin-coated 50nm thick semiconductor layer. The average electric field of the proposed device reaches 1.18MV/cm before an avalanche-like breakdown occurs. The physical nature of the breakdown mechanism is explored using the 1-D PIN equivalent structure and avalanche breakdown theory. The correctness and effectiveness of the proposed LDR-OFET and breakdown analysis are well demonstrated and validated by experimental results. The LDR-OFETs are expected to fill the blank of organic power devices and be the core component of future organic power integrated circuits.

Simulation Analysis of Electrical-Thermal-Fluid Coupling Property for Supporting Insulation in SF6 Filled HVDC Apparatus

Supporting insulation in SF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> -insulated high voltage direct current (HVDC) apparatus is a complicated issue as it involves the coupling behavior of electric field distribution, heat transfer process, and fluid property of SF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> gas. So far, comprehensive work investigating the insulation performance in this multiphysics coupled field has been absent. In this article, the distribution characteristics of state parameters in SF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> -insulated ±800-kV dc wall bushing have been simulated and analyzed under various coupled fields. The simulation result shows that, when the fluid behavior of SF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> gas is taken into consideration, the temperature and electric field distribution are substantially different from those in previous studies. Particularly, the postinsulator right above the HV conductor suffers from the concentration of high normal electric field, high tangential field, and a relative high temperature near the metal shell side, which greatly threatens the long-term insulation performance of the insulator and increases the risk of flashover. Furthermore, this article has investigated the effect of different supporting structures and material properties on the insulation performance of the bushing, based on which suggestions for insulator layout and material modulation are proposed. This article can serve as a reference for subsequent design and fault analysis on SF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> -insulated HV apparatus.

EMHD hybrid squeezing nanofluid flow with variable features and irreversibility analysis

This study discusses the entropy generation analysis of electro-magneto hydrodynamics (EMHD) hybrid nanofluid copper oxide-aluminum oxide/ethylene glycol (CuO–Al2O3/C2H6O2) flow amidst two rotating disks in a porous media having variable thermophysical features. The addition of the surface catalyzed to the homogeneous-heterogeneous reactions shorten the reaction time that may be taken as a novel aspect of the undertaken EMHD hybrid nanofluid squeezing flow. The inimitability of the assumed model is supplemented by considering the simultaneous effects of the variable thermal conductivity and viscosity. To simplify the governing flow model, suitable conversions are used to accurately translate the obtained partial differential equations to ordinary differential equations. The flow and energy transfer characteristics are computed and sketched graphically by using the Keller box scheme. The outcomes reveal that the drag force in radial and tangential directions depict the opposing trend for variable viscosity parameter. Furthermore, the normal magnetic and transverse electric fields play an essential role in the alignment of the nanoparticles throughout the flow field. The validation of the envisaged model is also a part of this study.

Enhanced energy storage performance in (1-x)Bi0.85Sm0.15FeO3-xCa0.5Sr0.5Ti0.9Zr0.1O3 relaxor ceramics

Producing dielectric ceramics with favorable energy storage density, efficiency, and thermal stability has become an urgent task for developing energy storage devices. In this work, the innovative Pb-free (1-x)Bi0.85Sm0.15FeO3-xCa0.5Sr0.5Ti0.9Zr0.1O3 [(1-x)BSF-xCSTZ, x = 0.0, 0.1, 0.2, 0.3 and 0.4] ceramics were fabricated via traditional solid phase sintering approach. Their structures, electrical characteristics, and energy storage properties were researched comprehensively. The results verified that all the samples form solid solutions with pseudo-cubic perovskites structure. The density of ceramic samples is improved accompanied by gradually refined grain size upon increasing the CSTZ doping content. Interestingly, an excellent recoverable density of ∼3.3 J/cm3 with high efficiency of ∼78% is received at x = 0.3 under the average breakdown electric field of 350 kV/cm. The energy storage performances remained stable in a broad temperature range of 20 – 110 ℃, a large frequency range of 1 Hz – 1 kHz, and beyond 105 repeated charging-discharging cycles. The enhanced energy storage performances of BSF ceramics by introducing CSTZ result from the improved relaxor behavior and the increased electric breakdown strength. Our strategy for relaxor modulation with a sealed sintering method to achieve high energy storage performance can be valuable in BiFeO3-based ceramic capacitors.

The joint influence of normal vibrations and electric field on the stability of a two-layer fluid system

The article focuses on the joint influence of normal vibrations and normal electric field on the stability of a system consisting of two flat horizontal fluid layers. Two cases are considered. In the first one, the system is formed by two layers of dielectric fluids (both layers have the same thickness) and, in the second, the system includes a dielectric fluid layer and an ideal electrically conductive fluid layer. The results obtained for these two cases are qualitatively similar. We study two approximations: the low-viscosity approximation and high-frequency vibrations. For the low-viscosity approximation, the so-called electric instability mode and the resonant mode are analyzed. In this case, the short-wavelength and long-wavelength instability modes are considered. In the low viscosity approximation, there occurs a viscous boundary layer, which is analyzed using a fast coordinate. The problem is studied by applying a multiscale method. It is demonstrated that vibrations increase the critical value of the electric field strength for short-wave instability in the presence of an electric mode. In the case of the long-wave instability, vibrations increase the curvature of the neutral curve near the zero value of the wave number. As for the influence of the electric field on resonant modes, it can lead to the splitting of the first resonance into two or three modes, depending on the values of the Weber number. When splitting is absent, the electric field reduces the critical amplitude of the first resonant mode. Otherwise, the effect of the electric field is more complex. In the high-frequency limit, the expressions describing the critical value of the electric field strength are similar to those for the electric mode considered in the low-viscosity approximation for finite vibration frequencies, and no resonant perturbations occur in this case.

Measuring 5G Electric Fields Strength With Software Defined Radios

The effect of electromagnetic radiation on public health is a recurring topic in the societal and political discourse, peaking with the introduction of every new generation of cellular technology. With the introduction of 5G, promising high peak download speeds as well as high-power beams, there is a need to revisit traditional measurement approaches. ICNIRP, a.k.a the International Committee on Non-Ionising Radiation Protection, offers a useful guideline to evaluate the electromagnetic field exposure of living tissues and provides some limits to keep exposure well below the threshold where it is considered harmful. However, modern packet radio technologies such as 5G or Wi-Fi are different from old broadcasting technologies. They deliver high power in very short bursts, spread over a wide band, thus increasing the difficulty of measuring electric fields with traditional instruments, such as spectrum analyzers. In addition, 5G promises a high spatial focusing performance, which means that the field can vary significantly even in a small area. Hence, measurements with a higher spatial density than we can achieve with expensive and bulky spectrum analyzers are urgently needed. Software-defined radios (SDRs), as a size-and cost-efficient alternative, can be used to capture signals in the time domain and thus increase measurement accuracy. However, software-defined radios are not designed to be used as RF power meters. They require accurate calibration and data analysis to ensure the measured power is correct. The aim of this work is to provide a general framework to calibrate SDRs, enabling them to measure RF power and extract the corresponding electric field value. Subsequently, the influence of the SDR parameters on the accuracy of the electric field measurement is investigated. To assess the performance of the proposed calibration framework in a real-life scenario, we rely on our private 5G network with a calibrated SDR to measure the RF power from a 5G network. Our measurements show that the average electric field exposure of 5G networks is well below 1 V/m.

Novel free surface electrospinning for preparing nanofibers and its mechanism study

In order to meet the increasing demand for nanofibers and overcome the disadvantages of traditional electrospinning technology, it is necessary to research an electrospinning device that can produce nanofibers efficiently. In this paper, a free surface electrospinning device was improved, and a spherical section free surface electrospinning device was developed to prepare high-quality polyacrylo-nitrile nanofibers in batches. Meanwhile, MAXWELL 3-D software was used to simulate the electric field distribution of the spherical section free surface electro-spinning with solution reservoirs of different spherical radii. The influence of the spherical radius on the spinning effect was analyzed to study the spinning mechanism. The results showed that when the applied voltage was 40 kV, the electric field distribution of the spherical section free surface electrospinning with a larger spherical radius was more uniform, the nanofiber diameter was larger, the nanofiber diameter distribution was more uniform, and the yield of nanofibers was higher. When the spherical radius was 75 mm, the quality of nanofibers was better, and the yield could reach the maximum value of 14.35 g per hour, due to its higher average electric field intensity and uniform electric field distribution.

Indoor Electromagnetic Radiation Intensity Relationship to Total Energy of Household Appliances

The rapid technological developments in the modern era have led to increased electrical equipment in our daily lives, work, and homes. From this standpoint, the main objective of this study is to evaluate the potential relationship between the intensity of electromagnetic radiation and the total energy of household appliances in the living environment within the building by measuring and analyzing the strength of the electric field and the entire electromagnetic radiation flux density of electrical devices operating at frequencies (5 Hz to 1 kHz). The living room was chosen as a center for measurement at 15 homes in three different environmental regions (urban, suburbs, and open areas). The three measurement methods are (Mode 1: people in a sitting position with electrical appliances on. Mode 2: People in a standing position with electrical appliances on. Mode 3: People are in the upright position while turning off the electrical devices) in the living room. These measurement methods and their results reinforce the importance of this research. The results showed that the average electric field strength measured in Mode 2 is much greater than the two methods, and we also found less electromagnetic radiation in Mode 3 than in the two modes. All results remain within the recommended overall exposure developed by the International Committee for the Prevention of Non-Ionizing Radiation and the International Electrotechnical Commission.

Active heat transfer enhancement by interface-localized liquid dielectrophoresis using interdigitated electrodes

We introduced an active heat transfer control between graphene and water using interdigitated electrodes (IDEs). Oppositely charged co-planer electrodes embedded on a graphene surface created a non-uniform electric field. Resulted interface localized liquid dielectrophoresis (LDEP) perpendicular to surface enhanced the water/graphene coupling and decreased interfacial thermal resistance (ITR) substantially. We correlated the theoretical calculations of average electric field strength near surface with Kapitza values measured at corresponding electrode configurations. We obtained a unified linear variation of Kapitza as a function of average electric strength independent of electrode size and charge. By increasing the electric field strength, we measured up to 96% decrease of Kapitza near electrodes. Since the IDEs generated electric field was only interface localized, it required lower electrode charges than any parallel-plate capacitor systems. We showed that ITR remains effective in heat transfer behavior for systems as big as 100nm such that interface localized electric field can at least increase the heat removal 50% by eliminating the ITR from both graphene/water interfaces of a channel system. By converting hydrophobic few-layer graphene to super-hydrophilic condition with ultra-low Kapitza, current results are important for graphene-based materials considered for the solution of the thermal management problem of current and next generation micro/nano-electronics.

Comparative Study of Hall Effect Mobility in Inversion Layer of 4H-SiC MOSFETs With Nitrided and Phosphorus-Doped Gate Oxides

In this study, the inversion layer mobility characteristics in Si-face 4H silicon carbide (SiC) metal-oxide-semiconductor field-effect transistors (MOSFETs) with nitrided and phosphorus-doped gate oxides were compared using Hall effect measurements. The inversion layer mobility was evaluated by applying a body bias and changing the temperature. The carrier scattering properties were determined for elevated temperatures (i.e., 473 K), at which point the impact of Coulomb scattering decreases and that of phonon scattering increases. The phonon-limited mobility of these MOSFETs was almost the same when plotted as a function of the effective normal electric field in the inversion layer, possibly representing the nature of the thermally grown SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> /SiC interface. On the basis of this finding, the effect of phonon scattering was separated from the inversion layer mobility. The MOSFETs exhibited a remarkable difference in Coulomb scattering: the MOSFETs with phosphorus-doped gate oxide exhibited a more rapid increase in Coulomb-limited mobility with increasing surface carrier density than did the MOSFETs with nitride gate oxide. This resulted from the effective suppression of Coulomb scattering in the inversion layer, which is one of the reasons why phosphorus-doped gate oxide achieves higher inversion layer mobility than nitrided gate oxide. These results show that the inversion layer mobility of SiC MOSFETs can be modeled using a conventional framework of phonon, Coulomb, and surface roughness scattering. Therefore, the suppression of Coulomb scattering is key to further improving the inversion layer mobility of SiC MOSFETs.

Features of the electron avalanche formation process in a strongly inhomogeneous electric field under high overvoltages

The simulation of the electron avalanche formation process in subnanosecond discharges of high pressure was carried out by means of the Monte-Carlo approach. The discharge gap under consideration was of the configuration “the finger-shaped cathode – the hemispherical anode”. The presence of a conic-shaped microprotrusion on a cathode surface was assumed. Such the electrode configuration provided the strongly inhomogeneous distribution of an electric field. A gas simulated was nitrogen at a pressure of 6 atm. An average electric field strength across the discharge gap was varied from 200 kV/cm up to 400 kV/cm. Microprotrusion height was varied from 0 um up to 30 um. The critical size and formation time of an electron avalanche were determined under various conditions simulated. The threshold electric field strength for electrons to transit into the continuous accelerating regime was calculated for various heights of the microprotrusion. The applicability of the non-self-consistent Monte-Carlo technique for the investigation of the runaway electron kinetics and the correct simulation of the runaway electron beam transport across the discharge gap was shown.

Effects of High Magnetic Field on Partial Discharge and Flashover Behavior of Epoxy Resin

High-field magnets use epoxy resin as the insulation for superconducting coil terminals. Surface flashover on the interface between the gas and solid insulation will cause insulation failure. In this paper, effects of high magnetic field on surface partial discharge and surface flashover of the epoxy resin are investigated. Experimental results show that high magnetic field causes the decrease of relative permittivity and further changes the electric field distribution along the surface of epoxy resin. Surface partial discharge behavior is directed by both the decrease of surface electric field at the interface and the decrease of breakdown voltage of air gap in high magnetic field. Lorentz force begins to play a role during the extension of electron avalanche by changing the migration of charge carriers and weakening the equivalent effect of the normal electric field near the triple junction. Opposite trends are observed with the increase of magnetic flux density when the direction of Lorentz force is parallel or perpendicular to the surface of epoxy resin.

Thermocapillary instability in the presence of uniform normal electric field: effect of odd viscosity

Thermocapillary instability in the presence of uniform normal electric field: effect of odd viscosity

Electrohydrodynamic instabilities in freely suspended viscous films under normal electric fields

We study electrohydrodynamic instabilities in a freely suspended liquid film subject to a normal electric field. The behavior of the system is characterized as a function of the relevant dimensionless groups during the linear and nonlinear regimes of growth. We demonstrate how the coupling of flow and surface charge transport in different modes of instability can give rise to manifold nonlinear phenomena such as tip streaming or pinching of the film into droplets.

Power Density Measurement within Kaduna North Area of Kaduna State, Nigeria

The measurement of possible presence of radiofrequency (RF) radiations from telecommunication base stations was carried out within Kaduna North Area of Kaduna State, to estimate the maximum level of power density from RF radiations to which the member of the populace within specific radius from the base transceiver station (BTS) are exposed to in relation to the existing guidelines to human exposure. Power density S (µWm-2) measurements were made at interval of 20 m to check the exposure level at public locations from 10 RF antenna sites starting from the foot of each BS to distance (radius) of 100 m using Aaronia Spectran HF-4060 Analyser and the electric field strength E (Vm-1) were calculated. The highest and lowest value obtained from measured mean power densities were 108.27 µWm-2 and 94.74 µWm-2 from a distance of 100 m and 40 m respectively. Also, the highest and lowest average electric field strength were 202.03 (Vm-1) and 188.99 (Vm-1) at 100 m and 40 m respectively. The result obtained, indicates that the measured values were far less than the permissible exposure limits for both workers and the general public as set by the International Commission on Non-ionizing Radiation Protection (ICNIRP). These results shows that the exposure levels in these areas are low and as such will not pose significant health risks to the people living in the study area.