Effect Of Electric Field Distribution Research Articles

Effect of improved electric field distribution on jet motion, fiber morphology, and properties of electrospun thermoplastic polyurethane fibrous membrane

AbstractElectric field plays a pivotal role in electrospinning to produce the desired micro and nanofibers, hence, a tricipital‐needle spinneret was developed to improve electric field distribution and productivity in this work. The effects of electric field distribution induced by spinneret configuration on jet motion, fiber morphology, and properties of electrospun TPU fibrous membrane at different applied voltages were investigated by simulation and experiment. The simulation results show that the designed tricipital‐needle spinneret weakens the electric field near the needle tip and strengthens the electric field in the whipping region in comparison to the single‐needle spinneret, exhibiting a relatively uniform electric field distribution. The experimental results demonstrate that the fiber diameter prepared by the tricipital‐needle spinneret at the corresponding voltage is smaller than that of the single‐needle spinneret due to the improved electric field distribution. Moreover, the fibrous membrane prepared by the tricipital‐needle spinneret shows excellent tensile properties (7 MPa tensile stress and 401% breaking elongation), air permeability (85.32 mm s−1) and water vapor permeability (6.7 kg m−2 d−1). Therefore, the electrospinning system with the tricipital‐needle spinneret not only increases the fiber productivity, but also improves the electric field distribution and endows the fibrous membrane with better properties, which can widen the applications of electrospun TPU fibrous membrane and also provides a new approach for the performance design of other electrospun fibers.

Electric field simulation of multi-needle water bath electrospinning and the structural properties of SCN/PAN micro/nanofiber composite yarns

Multi-needle water bath electrospinning is one of the most efficient methods used to prepare micro/nanofiber composite yarns. The nanofiber structure can be targeted and regulated to obtain high-performance composite yarns. To explore the effect of the receiving distance on the structure and properties of micro/nanofiber composite yarns, polyacrylonitrile nanofibers were uniformly coated on silver-coated nylon yarn via a four-needle continuous water bath electrospinning method. The electric field distribution at different receiving distances was simulated by ANSYS finite element analysis software, and the effects of electric field distribution on the structure and properties of the micro/nanofiber composite yarns were studied. The results indicated that the peak electric field intensity appeared at the tip of the needles and decreased with the increase in the receiving distance. The receiving distance was constant, and the field intensity was lower when the direction of the centerline of the needle tip was farther away from the tip; however, the field intensity at the conductive core yarn was higher than that in the surrounding area (small spikes). The average field intensity of the small spikes at 180 mm was only 1/4 of that at 80 mm. When the receiving distance increased within a certain range (100∼140 mm), the nanofibers had a smooth surface and good separation, their diameters decreased continuously and the porosity changed inversely. With a further increase in the receiving distance, the nanofibers gradually bonded, their diameter increased and the porosity showed the opposite trend. The coating rate of the nanofibers showed a decreasing trend, and the mechanical properties of the micro/nano composite yarns were improved. When the receiving distance was 100 mm, the porosity reached 38.94%, and the breaking force, breaking elongation and breaking strength were 13.71 ± 1.36 cN, 22.76 ± 6.62% and 0.15 ± 0.02 cN·dtex−1, respectively. Upon consideration of all the above factors, the receiving distance of 100 mm is appropriate.

Electrical degradation dynamics of glass fiber-reinforced epoxy composites considering different fiber orientation

Glass fiber-reinforced epoxy composites (GFREC) have been widely used in the mechanical components of electrical and electronic devices because of its lightweight, high mechanical strength, excellent electrical insulation properties and corrosion resistance. The research on the electrical degradation dynamics of GFREC is of great significance to avoid the failure of electrical insulation system. Herein the composite samples were prepared using vacuum impregnation technique. The electrical degradation morphology and statistical characteristics (electrical tree length, width, expansion coefficient, breakdown probability and breakdown time) were discussed. The results show that the electrical tree will develop towards the fiber side and grow rapidly along the interface in GFREC. The interfacial orientation will affect the growth characteristics of electrical tree. When the angle between the glass fiber and the needle electrode is 45°, the composite material has relatively superior tree propagation resistance performance, lower breakdown probability and higher breakdown time. The effects of electric field distribution on the tree initiation and electrical degradation are discussed, which reveals the relationship between the electrical degradation and the fiber orientations. The electric field-driven tree growth (FDTG) model is used to explain the growth of trees along interfaces with different orientations from the perspective of dynamic electric field distribution.

RF-Characterization of HZO Thin Film Varactors

A microwave characterization at UHF band of a ferroelectric hafnium zirconium oxide metal-ferroelectric-metal (MFM) capacitors for varactor applications has been performed. By using an impedance reflectivity method, a complex dielectric permittivity was obtained at frequencies up to 500 MHz. Ferroelectric Hf0.5Zr0.5O2 of 10 nm thickness has demonstrated a stable permittivity switching in the whole frequency range. A constant increase of the calculated dielectric loss is observed, which is shown to be an effect of electric field distribution on highly resistive titanium nitride (TiN) thin film electrodes. The C-V characteristics of a “butterfly” shape was also extracted, where the varactors exhibited a reduction of capacitance tunability from 18.6% at 10 MHz to 15.4% at 500 MHz.

Effect of Electric Field Distribution on the Heating Uniformity of a Model Ready-to-Eat Meal in Microwave-Assisted Thermal Sterilization Using the FDTD Method.

Microwave assisted thermal sterilization (MATS) is a novel microwave technology currently used in the commercial production of ready-to-eat meals. It combines surface heating of high-temperature circulation water with internal microwave heating in cavities. The heating pattern inside the food packages in a MATS process depends heavily on the electric field distribution formed by microwaves from the top and bottom windows of the microwave heating cavities. The purpose of this research was to study the effect of the electric field on 922 MHz microwave heating of ready-to-eat meals as they moved through the microwave chamber of a pilot-scale MATS system using the finite-difference time-domain (FDTD) method. A three-dimensional numerical simulation model was developed as a digital twin of the MATS process of food moving through the microwave chamber. The simulation showed that the electric field intensity of the MATS microwave cavity was greatest on the surface and side edge of the cavity and of the food. There was a strong similarity of the experimental heating pattern with that of the electric field distribution simulated by a computer model. The digital twin modeling approach can be used to design options for improving the heating uniformity and throughput of ready-to-eat meals in MATS industrial systems.

Effects of Electric Filed on Electrospray Process: Experimental and Simulation Study

At present, there exists a widely-held view that electric field plays an extremely important role in the electrospray process. Aimed at investigating into the effects of electric field distribution and intensity on the electrospray process and resultant microsphere diameter, a variety of necessary and relevant tests were performed in this study by inviting an auxiliary electrode ring. The three-dimensional electric fields of the electrospray system were simulated, in addition, high-speed photography was adopted to recognize the electrospray modes. The results of a series of electrospray experiments demonstrated that not only electrospray mode but also resultant microsphere diameters are influenced, to a considerable degree, by the electric field. Such simulation results were verified by above-mentioned experiments that from higher electric field intensity comes smaller microsphere diameter, due to the fission caused by the surface charge, and besides, more uniform electric field distribution produces more uniform microsphere diameter.

The Effects of Electric Field Distribution on the Interface Stability in Solid Electrolytes

Ceramic electrolytes could potentially enable Li metal anodes, leading to safer and more energy dense solid-state batteries. However, it has been hypothesized that electric field amplification at electrode edges can destabilize the interface and lead to short circuiting during charging. By comparing models of the electric field distribution at the electrode/electrolyte interface for varying electrode geometries with experimental solid-electrolyte systems, we show that areas of high electric field can localize at sharp corners, which may facilitate Li metal penetration at these locations. Symmetric Li/ Li6.5La3Zr1.5Ta0.5O12 (LLZO) cells were cycled until failure and the spatial distribution of the degradation was analyzed using electron microscopy. We report a decrease in nominal critical current density (CCD) from 1.48 to 1.26 mA cm−2 due to a 15% increase in electric field from edge effects. Moreover, when considering the CCD locally at spots of high electric field amplification, we find current densities of at least 4 mA cm−2 can still be sustained. Non-uniform electric field distributions at the Li/LLZO interface could play a major role in determining cycling capabilities and failure modes of solid-state batteries and may also have important implications for the manufacturing of Li metal battery electrodes.

Experimental studies on the effect of electrostatic boundary conditions and frequency on the performance of a trigrid electrostatic coalescer

In this work, we explore the effect of electric field distribution and incorporating two different frequencies in two different regions of a trigrid coalescer on the electrocoalescer efficiency. Specifically grounding water at the bottom of the coalescer is found to be effective. The effect of frequency on emulsion breakup is essentially due to chaining tendency of water droplets at high frequencies. The reason for this could be reduced electrostatic force between drops at higher frequencies due to higher capacitance of interstitial oil film between two droplets. Moreover, at low frequencies significant bouncing of drops from interface is observed, leading to lower separation rates.

Graphene-Coated Optical Fiber SPR Biosensor for BRCA1 and BRCA2 Breast Cancer Biomarker Detection: a Numerical Design-Based Analysis

This paper provides a simple hybrid design and numerical analysis of the graphene-coated fiber-optic surface plasmon resonance (SPR) biosensor for breast cancer gene-1 early onset (BRCA1) and breast cancer gene-2 early onset (BRCA2) genetic breast cancer detection. Two specific mutations named 916delTT and 6174delT in the BRCA1 and BRCA2 are selected for numerical detection of breast cancer. This sensor is based on the technique of the attenuated total reflection (ATR) method to detect deoxyribonucleic acid (DNA) hybridization along with individual point mutations in BRCA1 and BRCA2 genes. We have numerically shown that momentous changes present in the SPR angle (minimum: 135% more) and surface resonance frequency (SRF) (minimum: 136% more) for probe DNA with various concentrations of target DNA corresponding to a mutation of the BRCA1 and BRCA2 genes. The variation of the SPR angle and SRF for mismatched DNA strands is quite negligible, whereas that for complementary DNA strands is considerable, which is essential for proper detection of genetic biomarkers (916delTT and 6174delT) for early breast cancer. At last, the effect of electric field distribution in inserting graphene layer is analyzed incorporating the finite difference time domain (FDTD) technique by using Lumerical FDTD solution commercial software. To the best of our knowledge, this is the first demonstration of such a highly efficient biosensor for detecting BRCA1 and BRCA2 breast cancer. Therefore, the proposed biosensor opens a new window toward the detection of breast cancers.

FDTD Analysis Fiber Optic SPR Biosensor for DNA Hybridization: A Numerical Demonstration with Graphene

This article illustrates a design and finite difference time domain (FDTD) method based on analysis of fiber optic surface plasmon resonance (SPR) biosensor for biomedical application especially for DNA-DNA hybridization. The fiber cladding at the middle portion is constructed with the proposed hybrid of gold (Au), graphene, and a sensing medium. This sensor can be recognized adsorption of DNA biomolecules onto sensing medium of PBS saline using attenuated total reflection (ATR) technique. The refractive index (RI) is varied owing to the adsorption of different concentration of biomolecules. Result states that the sensitivity with a monolayer of graphene will be improved up to 40% than bare graphene layer. Owing to increased adsorption capability of DNA molecules on graphene, sensitivity increases compared to the conventional gold thin film SPR biosensor. Numerical analysis shows that the variation of the SPR angle for mismatched DNA strands is quite negligible, whereas that for complementary DNA strands is considerable, which is essential for proper detection of DNA hybridization. Finally, the effect of Electric field distribution on inserting graphene layer is analyzed incorporating the FDTD technique by using Lumerical FDTD solution software.

Effect of Electric Field on the Directly Electrospun Nanofiber Yarns: Simulation and Experimental Study

Electric field plays a key role in electrospinning process for nanofiber and nanofiber yarn producing. The electric field distribution of the yarn manufacturing system is simulated by using finite element method analysis. The effects of electric field distribution and intensity were studied to analyze the influence of the electric field on the electrospun nanofiber yarn surface morphology, mechanical, thermal and water absorption properties. The results show that the morphology and diameters of nanofiber and yarn were obviously affected by the electric field with changing the needle distance and applied voltage, which further influence the mechanical performance of the yarn. The needle distance does not much affect the thermal property of the PSA electrospun yarn, whereas the yarn obtains better thermal resistance properties at voltage of 25 kV. The nanoyarn electrospun and assembled under higher applied voltage is proved to have a better wicking property in our research.

Effect of Electric Field Distribution on Pulse Electrochemical Machining of Small Holes with Tubular Electrode

Effect of Electric Field Distribution on Pulse Electrochemical Machining of Small Holes with Tubular Electrode

Effect of electric field on the morphology and mechanical properties of electrospun fibers

Three kinds of spinnerets containing single needle, sharp and blunt cones were used to study the effect of electric field distribution on the morphology and mechanical properties of the as-prepared fibers.

Modelling on Tracking Test Condition of Polymer Nanocomposite using Finite Element Simulation

Electrical tracking is a formation process of a permanent conducting path across the insulating material due to surface erosion under high voltage stress. The existing of leakage current (LC) on the wet contaminated material surface causes the generation of surface discharges that resulted in the material degradation. The effects of electric field distribution and current density on LLDPE-Natural Rubber blends material were investigated using finite element method (FEM) analysis. In this paper, a variety of physical parameters particularly contaminant flow rate, various applied voltages, material properties of permittivity and conductivity were studied when nanofiller is added to LLDPE-Natural rubber blend. The simulation works using FEM software of Quickfield was applied to the tracking test condition of IEC 60587 standard. The results show that the electric field distributions are critical on the edges of contaminant solution path at higher voltage level. The current density and electric field distribution is increase with higher applied voltage. The polymer nanocomposite with 1-5 % of nanofiller exhibits a good resistance to tracking and erosion test.

Effects of electric field distribution and water drop ejection on flashover of icicles in plane-to-plane gaps

Ice morphology was established from field failure observations on electrical insulators, considering partial and full bridging conditions. Small scale laboratory simulations showed an important effect of droplet ejection on the probability of flashover. During the experiments, factors including applied water conductivity, icicle length, combinations of air gap and icicle length and duration of melting period were investigated using typical in-service stress levels. According to the experimental results, applied water conductivity and icicle length affected the residual ice layer resistance. Flashover voltage decreased by 33% as the conductivity increased from 150 μS/cm to 750 μS/cm and reduced by 10% as icicle length declined from 6 to 4 cm for constant 2-cm air gap. Fully bridged icicles required extra energy for ice melting, leading to higher flashover voltage compared to partially bridged icicles of the same morphology. A single 3-cm air gap had 14% higher flashover voltage than a pair of 1.5 cm air gaps.

Measurement of optical signals as a plasma propagation in the atmospheric pressure plasma jet columns

The propagation of plasma jets with argon gas is characterized in terms of two factors, the effect of electric field distribution along the tube and the effect of voltage polarity, from the observed results of optical signals along the entire column of plasma. The optical signal of plasma propagates from the high electric-field region of high-voltage electrode toward the low field region of the open air-space, regardless of the polarity of the voltage. The optical intensity and the propagation velocity are higher for the positive voltage than for the negative voltage. Moreover, the length of plasma plume exited from the end of the glass tube into the open air is shorter for the negative voltage. When the optical intensity is strong enough, a secondary peak signal follows the primary peak. In the plasma column on the inside of the glass tube, the optical intensity and the propagation velocity depend on the strength of the electric field; they are both high at the high-field region of voltage terminal and decay toward the end of the tube. The velocity is as fast as 104 m/s at the high-field region and slows down to 103 m/s at the low-field region of the glass-tube end. However, the plasma accelerates drastically to be (104–105) m/s after exiting the glass tube toward open air, even though the electric field is a quite low and thus the optical signal decays low before fading out. The experimental observations present in this report are explained with the propagation of the plasma diffusion waves.

Effects of electric field distribution on icing and flashover performance of 220 kV composite insulators

The energized icing of composite insulators has been studied by the researchers around the world, but not much about the effects of electric field distribution on their icing and flashover performance. For this purpose, the ice accretion and flashover performance of 220 kV composite insulators with two shed configurations on occasions of different electric field distributions considering the effect of grading rings are analyzed in this paper. The test results indicate that the intensity and homogeneous distribution of electric field have positive effects on the appearance, density and weight of ice; the improvement of electric field distribution after installing grading ring has more effects than the icing characteristics, such as quality, density as well as appearance of ice, on flashover voltages of ice-covered composite insulators; the icing flashover voltages are increased by the improvement of electric field distribution and the increasing ranges of icing flashover voltage were relied on shed configuration. Icing accumulation patterns have less effect on flashover performance of composite insulators with alternatediameter or widely spaced shed configurations.

Effect of Electric Field Distribution Generated in a Microspace on Pool Boiling Heat Transfer

This study describes the effect of an electric field on nucleate boiling and critical heat flux (CHF) in pool boiling. A dielectric liquid of AE-3000 was used as the working fluid. A heating surface was polished to a surface roughness of 0.05 μm. A microsized electrode, in which slits were provided, was designed to generate a nonuniform electric field and produce electrohydrodynamic (EHD) effects with the application of high dc voltages. The obtained results confirmed CHF enhancement as the EHD effects increased CHF to 86.2 W/cm2 with a voltage of −3000 V, which was four times greater than pool boiling in the absence of the electrode. The usual traveling wave on the bubble interface, induced by the Kelvin–Helmholtz instability, was modified by adding the EHD effects. The traveling wave model exhibits the essential features of the phenomenon and shows good agreement with the experimental data.

Effects of Structural Parameters on Nanofiber from a Multihole Electrospinning Setup

To meet a high production requirement and high quality of nanofiber, a new disgned multihole spinneret with equilateral hexagon hole array of is used in this paper. We study the effects of two structural parameters of the multihole system on fiber diameter and fiber mats. 3D electric fields were simulated to understand the effects of electric field distribution on electrospinning performance. This study shows that fine and uniform fibers, as well as concentrated and uniform fiber mat can be obtained by this multihole electrospinning system at a high production rate.

112 核沸騰における電界分布の影響(フェロー賞候補対象講演III)

112 核沸騰における電界分布の影響(フェロー賞候補対象講演III)