Papers by Keyword: Electric Field

Abstract: Cross-linked polyethylene is widely used as electrical insulation because of its excellent electrical properties such as low dielectric constant, low dielectric loss and also due to its excellent chemical resistance and mechanical flexibility. Nevertheless, the most important reason for failure of high voltage equipment is due to its insulation failure. The electrical properties of an insulator are affected by the presence of cavities within the insulating material, in particular with regard to the electric field and potential distributions. In this paper, the electric field and potential distributions in high voltage cables containing single and multiple cavities are studied. Three different insulating media, namely PE, XLPE, and PVC was modeled. COMSOL software which utilises the finite element method (FEM) was used to carry out the simulation. An 11kV underground cable was modeled in 3D for better observation and analyses of the generated voltage and field distributions. The results show that the electric field is affected by the presence of cavities in the insulation. Furthermore, the field strength and uniformity are also affected by whether cavities are radially or axially aligned, as well as the type of the insulating solid. The effect of insulator type due the presence of cavities was seen most prevalent in PVC followed by PE and then XLPE.

Abstract: This paper studied influence of three dimension complex ground on electric field under overhead lines. Surface charge method is discussed and planar triangle surface charge elements are used to represent complex ground. Electric field of overhead lines is analyzed by charge simulation method. Finite straight line charges are used to represent conductors. Then electric field of 220kV double circuit overhead lines over a three dimension small hill is calculated and distribution of electric field 1.5m above the ground is analyzed.

Abstract: The average particle size of synthesized nanoparticles (nps) was found to be about 34 nm as analyzed using scanning electron microscopy (SEM). The nonlinear optics measurements were performed by using z-scan method with 532 nm wavelength CW Nd:YAG laser. The influence of electric field on the nonlinear optical responses for nematic liquid crystals (NLCs) doped with nps was considered in different voltages. The measurements were performed with ferronematics for two commonly initial alignments (homogeneous and homeotropic) with small compositional percentage of magnetic nps (i.e. 1% W/W). The experimental results show that the magnitudes of nonlinearity in homeotropic alignment samples are larger than homogeneous ones. Results show that the applied electric field had a great effect on the nonlinear optical properties of NLCs doped with nps in homogeneous alignment samples and do not have any significant affect in homeotropic alignment samples.

Abstract: In the framework of effective mass approximation, the LandauPekar variational procedure is adopted to study the ground-state binding energy of a hydrogenic impurity in a semiconductor nanowire with finite confining potential subjected to both external fields (electric and magnetic) and electronpolar optical phonon interaction taking into account the phonon confinement effect. The results for the binding energy as well as polaronic correction are obtained as a function of the wire radius, impurity position and applied fields. Calculated results reveal that the values of the polaronic shifts of impurity binding energy can be quite different for cases with finite and infinite confining potentials.

Abstract: In this article, we use the molecular dynamic simulation to study the structure and transmission properties of polar fluid which is in the limited nature of nanochannel under the applied electric field. polar fluid is water. Simulation process is carried out under different electric field strength. The diffusion coefficient, density distribution, radial distribution function of water molecular in the same channel with different electric field strength and the same electric field strength of different pore are studied by the method of molecular dynamic simulation, obtained a conclusion that in a certain range of electric field intensity, the density of water distribution diffusion coefficient of the main conclusions of effects by the wall, but over a certain range, the electric field of influence will become obvious.

Abstract: Objective of the present study is to derive appropriate study factors upon introduction of purification technique with mounting of multi-type of electrical membranes in an industrial combined with contaminated underground water. For reaction times of 540mins, removal rates according to the strength of voltages were calculated and optimum operating factors of the electrical membrane were derived according to treatment conditions per concentration of electrode liquid using electrical membranes. The removal rates as a function of voltages were shown to be 88% at 15V for Ni, 65% and 68% at 15V and 20V, respectively, for Cr. In the comlex modulation electromagnetic field, Cr showed the removal rates of 80% and 85% at 15V and 20V, respectively, while Ni showed the removal rates of 94% and 97% at 10V and 15V, respectively. When the concentrations of electrode liquid (Na₂SO₄) were varied upon electrode membrane treatment, the removal concentration for 0.5% was 1.8mg/l in the case of 20V resulting in the removal rate of 91%. In case of 1% of electrode liquid (Na₂SO₄), the final concentrations at 15V and 20V were shown to be below 1mg/l in both cases, and high removal tates above 98.9% could be obtained in the treatement with combined application of the electromagnetic field.

Abstract: We used a simple low-temperature hydrothermal approach to synthesize Ag nanoparticles (NPs) and demonstrated their efficiency as organic molecule detectors in surface enhanced Raman Scattering (SERS). Using finite difference time domain simulation, we described an investigation on the distribution of electric fields amplitude of the neighboring Ag NPs. The enhanced electric field is confined at the interparticle gaps and the enhancement factor can be further increased with reducing the spacing between the NPs. The theoretical simulation demonstrated good consistency with the experimental measurement results, which predicts an electric fields amplitude enhancement of 115 at the center of NPs gap and an electromagnetic SERS enhancement of 10⁸. The evidence of clear correlations between SERS enhancement and morphology distribution offer a route to develop more effective SERS substrates.

Abstract: The drag of liquid flow is of interest in micro/nanoscale. Electroviscosity is one of the important factors which can affect drag. By applying electric filed between liquid and surface, the surface charge density can be changed, leading to a change of electroviscosity. This paper experimentally studied the effect of applying electric field on the surface charge density, and analyzed the change of electroviscosity with applying electric field. The electroviscosity is found abated with applying electric field which will decrease the drag of liquid flow.

Abstract: The processing simulation method of numerical control electrochemical turning (NC-ECT) was presented based on the finite element method (FEM) in this paper. The three-dimensional analysis model of the electric field built in ANSYS software was solved. The current density distribution and the theoretical values of material removed depth per revolution (MRDPR) in different time on the anode were obtained. The experiments were carried out on the NC-ECT lathe, and the measured values of MRDPR were measured, which were compared with the theoretical values. It is indicated that the maximum percentage error between the theoretical values and the measured values is smaller and the simulation method meets the accuracy of the engineering calculations.

Abstract: According to a company's actual process of producing coatings, Finite Element Method is adopted to simulate and analyze the variation rules of various fields and mechanical parameters during the preparing process of solar spectrum selective absorbing coating for medium-high temperature application using magnetron sputtering. The results show that during the process of magnetron sputtering, magnetic fields uniformly distribute around the target and the sputtering etching area can be a wide range of 180°. In the spaces for magnetron sputtering, the magnetic flux is maximum at the contact between the and the core, and the magnetic flux density distributes uniformly between the magnetic steel and the target; the magnetic induction distribute uniformly within the120°direction of the target and forming two planar track typed etched channels; when the cylindrical target rotates at a proper speed, a large area of coating in uniform thickness can be deposited on the matrix. The results provide theoretical guidance for actual production of preparing medium-high temperature selective absorbing coating of uniform thickness and excellent quality.