Papers by Keyword: Skin Effect

Abstract: Numerical analysis of distribution of resistive heat source in two-phase conducting medium (copper electrode – biological tissue) was carried out. Axisymmetric two-dimensional elliptic problem, with boundary conditions of the first and second kind was solved in the environment of MATLAB mathematical package, using the method of finite differences. Analysis results show that heat source concentration and other parameters are determined by skin effect. This fact should be taken into account in development of new effective methods of surgical treatment and respective instruments. This mathematical model can be applied in a wide frequency range for conducting materials with different conductivities.

Abstract: In the present paper, the comparison results of two main kinds of the power lines are presented, namely, overhead lines and cable lines. The analysis was done in the low-voltage mains network in the frequencies identified by the CENELEC organization for a narrowband transmission using low-cost PLC modems. The currently data transmission with the use of the PLC technique finds increasing use in the area of the communication for the Smart Grid, especially because of Smart Metering and Smart Lighting systems development. Independently form the implementation of the PLC transmission technique, a process of replacement of overhead lines with cable ones is carried out. Undoubtedly this process must have an influence on the transmission prosperities over the mains network. This paper is aimed to show differences in the secondary transmission parameter of the two main constructional types of low-voltage lines, which have the same electro-power parameter. The influence of these differences on the transmission quality is also discussed. The study has been limited to aluminium and copper wires and was made in the low-voltage mains network.

Abstract: According to the 66kV transformer blackout phenomenon, the oil chromatogram data analysis, found that the transformer existed temperature (676 °C) and low energy discharge defect. Through measuring the harmonic content to and analyzing the load condition, test results show that the grid was injected harmonic currents by the substation non-linear loads, its 5 times,7 times, 11 times, 13 times harmonic were higher than the state standards, this shows that the harmonic is the cause of the chromatographic data of transformer oil abnormal

Abstract: We designed and implemented a power converter to provide a dc power bus for the MCOR 12 correction supply. The characteristics of the dc power bus are variable frequency at both heavy and medium or light loads. These characteristics match the working requirement of the correction supply. The dc power bus has a relaxation oscillator that generates a symmetric triangular waveform, to which MOSFET switching is locked. The frequency of this waveform is related to a voltage to be modulated with feedback circuitry. As a result, the circuit and complex transformer are driven with a half-bridge. We designed the complex resonant transformer and describe in this paper a simulation model that is highly important, thus to exploit its frequency-dependent transfer characteristics. We obtained a power bus with small ripple to provide the correction power. The high-performance characteristics of the resonant dc power bus are illustrated in this paper.

Abstract: This paper presents a research on skin effect’s influence on the current density distribution of Cu/barrier layer and Cu/cap layer interfaces of copper interconnects’ via vicinities. A two-level Cu-interconnect structure in different positional relationships with the ground plane is discussed. Through the three-dimensional (3D) finite element simulation of the interconnect structure, the variations of current density on three important surface areas are obtained when skin effect is significant, showing that the current density in the three surface areas near the via has been strongly influenced by current crowding and skin effect. So in many cases the influence of skin effect on via top and via bottom failures of Cu interconnects under high frequencies can not be ignored.

Abstract: Electrode wear has a great adverse effect on the accuracy of Micro Electrical Discharge Machining (Micro-EDM) and impedes the improvement of Micro-EDM. In this study the distribution of electric field and current density was analyzed exhaustively in order to explore the generating mechanisms of rod electrode wear by finite element analysis and experiment. Experimental results indicated that corner wear occurred first, followed by side wear resulted from skin effect and debris in Micro-EDM, which was significant in enhancing the accuracy of machining.

Abstract: According to the principle of induction heating, the skin depth of shrink-fit chuck is determined and the mathematical model of induction heating is constructed. Then a finite element model of induction heating for shrink-fit chuck based on FEM software is set up and the electromagnetic field, temperature field and structure field are obtained. In the end, the paper discusses the influence of the position, current frequency and current density of the coil on the deflection of the clamping bore. Research work provides a theory reference for the design of shrink-fit tool holder and shrink-fit machine.

Abstract: Many factors may affect array induction log, including skin effect. In this paper, according to relative formula deduced, a correction method of skin effect based on multi-frequency measurement signals is proposed using only the real component. This paper gives apparent conductivities that are from first order derivative correction and second order derivative correction by Chebyshev polynomial fitting method. Compared with measured data calculation, it showed that the correction results from the method above were in good agreement with the data from Express software.

Abstract: The main materials of polymer electrolyte membrane fuel cell (PEMFC) are carbon (C) and Stainless Steel (Fe). The dynamic current of PEMFC will cause nonuniform distribution of current density in these materials. Simple models which materials are carbon (C) and Stainless Steel (Fe) are used in testing. A testing device using electromagnetic method was set up to detect the induced electromotive force in models. Theoretical calculations using electromagnetism and mathematics are set up to calculate the current density distribution of models. It is shown from the comparison between calculated values of the formula and measured values that the dynamic current of PEMFC will cause skin effect.

Abstract: Repeated impact tests on a 1Cr18Ni9Ti sample and a 1Cr18Ni9Ti sample with Ni-2 laser cladding coating are done and grade test data were collected intermittently. The results show that under the repeated impact loading which is far below the yield strength of material, there will be plastic deformation on both 1Cr18Ni9Ti sample and 1Cr18Ni9Ti sample with Ni-2 laser cladding coating, and the deformation of the former is more than the latter. For the 1Cr18Ni9Ti sample: from the perspective of impact frequency, the deformation rate of the gridding in every layer is largest in initial thousands of times, with the increasing number of impact, deformation rate decrease gradually, until zero; View from the layer in coordinates, more closer to the surface gridding layer, the deformation rate is larger, The average deformation rate of the gridding decreases continuously with the increasing layers deep. For the 1Cr18Ni9Ti sample with Ni-2 laser cladding coating: coating surface deformation is largest, change of gradient reduces gradually along the layer deep, that means repeated impact deformation has ‘skin effect’, the value is inversely proportional to the depth from the surface. The matrix deformation is similar with the coating, the value is inversely proportional to the distance from the faying surface.