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The present article describes 2D transient electric field calculation by finite element method. Special attention is given to the nonlinear dependence of insulation material resistivity on eclectic field strength under HVDC condition. Importance of taking it into account is shown by comparison calculation results.
A cylindrical metallic photonic crystal waveguide -design and analysis is reported. Air-core microstructured fiber has been demonstrated as a low loss dielectric waveguide for THz guiding is used to design this waveguide. It can be used as a slow wave structure (SWS), which is considered as a key element in backward wave oscillator (BWO) and other types of electron beam sub-millimeter wave sources...
We study theoretically the spin polarized electron field emission from carbon nanotube (CN) within an axial magnetic field. It is found that the spin polarization of emission current can reach 0.05~0.08 with 0.1~1 μA emission current in the magnetic field 6 T and the electric field 9~12 V/nm at room temperature. The spin polarizations of the energy distributions oscillate and the peaks reach to 0...
A comparative study of the effect of electrical fields on bifurcation phenomena appearing in biaxially stretched slabs of Mooney-Rivlin and Ogden materials is described. The main conclusion of the analysis is that the stretch ratio at which the bifurcation appears crucially depends on both, the configuration of the system sample-electrodes, and the model used.
Epoxy based compounds containing micrometric and nanometric silica were prepared. These were utilized in a comparative study to establish their dielectric behaviour. In this study, the weight %-content of the silica filler was varied as a parameter. Some filler distributions were characterized using TEM. In general, the micrographs illustrate a satisfactory dispersion, showing a nanostructured morphology...
Measurement of partial discharge (PD) has been used to assess the condition of insulating material used in electric power equipment. Analysis of the electromagnetic (EM) waves emitted from PD is useful from the viewpoint of noncontact diagnosis because PD emits wideband EM waves. The EM waves emitted from PD in insulating materials were numerically visualized using the constrained interpolation profile...
Perovskite materials are crucial in a variety of important technological applications. Using quantum-mechanical simulations and accurate molecular dynamics models, we have computationally investigated ferroelectric materials for applications in computer memory, piezoelectrics and photovoltaics. By tuning the applied electric pulses' shaping and delay separation, we find the lower limit for tetragonal...
Future developments of end corona protection (ECP) systems require calculation of the electrical field strength along the insulating surface and the temperature profile with satisfactory accuracy. This report presents an approach for the exact calculation of relevant physical parameters for a typical ECP configuration based on the finite element method, this approach accounting for the large electrical...
Nano-clay and micro-silica mixed composites were made for use as insulating materials for environmentally-friendly switchgear. The thermal properties and V-t characteristics of these composites were evaluated under a homogeneous electric field. They were shown to have sufficient thermal and insulation breakdown properties as insulating materials for switchgear. In particular, their average insulation...
A series of experiments were performed to remove toluene from a gaseous influent at normal temperature and atmospheric pressure by non-thermal plasma generated dielectric barrier discharge coupled with nano-Ba0.8Sr0.2Zr0.1Ti0.9O3 catalyst. We were innovative to prepare nano-Ba0.8Sr0.2Zr0.1Ti0.9O3 catalyst by ourselves and use it in the plasma reactor. The best removal efficiency of toluene arrives...
Using the tunneling effect under high electric field, field emission cold cathode could obtain an emission current which is large enough. In this paper, we reported the large field-emission from CNTs and ZnO tetrapods composited field emitters. Screen-printing method is used in our experiment and more than 15 mA field-emission current is obtained with 0.5 mm gap.
The bending effect of piezoelectric quartz is investigated by the theories of elasticity and electromagnetism. First the bending stress is deduced using mechanics of material. According to piezoelectric equation the volume and surface bound charge densities by bending are calculated. Using Finite Element Method, the distribution of the electric field in quartz bar is simulated. Based on the theoretical...
In one of the new “root-E” models for TDDB, there is a second term in the exponent representing the probability that there is enough energy to create damage that contributes to breakdown failure. This provides an exponential “1/E” character to the extrapolation to use conditions that predicts lifetimes many orders of magnitude longer than the simple root-E extrapolation. It also predicts a threshold...
This paper presents a generalized continuum design sensitivity formula that is applicable to all cases of the shape optimization of high-frequency devices. Using the proposed approach, it is easy to deal with any shape design problems concerning conducting surfaces as well as dielectric contours. The derived sensitivity formula has been successfully applied to shape optimization of a waveguide T-junction...
This paper presents an efficient approach to determining the corrosion currents distributed on the hull of a naval ship, which offer useful information for underwater electric fields prediction and diagnosis of hull corrosion state. To achieve this, a material sensitivity formula, which gives the first-order gradient information of an objective function with respect to the electric current, is analytically...
In this paper, wave propagation in two-layered anisotropic media when uniaxially anisotropic medium has its optic axis oriented vertically and tilted around z-axis has been investigated. The Fresnel coefficients are derived for horizontally and vertically polarized incident waves with arbitrary incident angles. The contribution of the cross polarized components of the reflected and transmitted waves...
Dielectric elastomers have demonstrated most potential as muscle-like actuators because they can undergo large deformation, have a high energy density and a relatively fast response. The basic structure of a dielectric elastomer (DE) is simple - an elastomer film sandwiched between two electrodes. The electrodes that sandwich the elastomer play a key role in the electromechanical performance. The...
Electrical leak location methods are effective and widely used in landfill leakage detection. They make use of the high resistivity of the geomembrane liner. When a leak occurs in the liner, it provides a path for the current causing a potential anomaly in the vicinal medium. Then, the leak can be located by measuring the potential distribution patterns. The earth noise, natural electric field, electrode...
A two-dimensional zeroth order resonator (2D ZOR) artificially composed of an array of metal rods is designed. A metal rod material which supports 2D backward waves is fabricated and tested at a 2GHz band. Near field measurement results show negative refractive index characteristics which agree well with simulated results. A ZOR operation with an infinite wavelength is experimentally confirmed by...
Tissues formed by cells seeded in hydrogels are used for biotechnology, cell-based assays, and tissue engineering. We have previously presented a cell-micropatterning technique that localizes live cells within hydrogels using dielectrophoretic (DEP) forces, and have demonstrated the ability to modulate tissue function through the control of microscale cell architecture. In this study, we developed...
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