A fluid-thermal coupled analysis based on FEM is conducted. The inner structure of the coils is built with consideration of both the structural details and the simplicity;thus, the detailed heat conduction process is ...
To clarify the dependence of arc duration on atmosphere, experiments were conducted under conditions of air, N2, Ar, He and CO2 with the pressure of 0.1MPa in a 14V/28V/42V circuit re spectively.A quantitative relatio...
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To clarify the dependence of arc duration on atmosphere, experiments were conducted under conditions of air, N2, Ar, He and CO2 with the pressure of 0.1MPa in a 14V/28V/42V circuit re spectively.A quantitative relationship between arc duration and gas parameters such as ionization po tential, thermal conductivity was obtained from the experimental ***, the inherent mechanism of influence of atmosphere on arc duration was discussed.
A short circuit in a power system can cause very high currents to flow to the fault location. The magnitude of the short circuit current depends on the impedance of system under short circuit conditions. However, to s...
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A short circuit in a power system can cause very high currents to flow to the fault location. The magnitude of the short circuit current depends on the impedance of system under short circuit conditions. However, to study the effect of windfarm integrated into Power Holding Company of Nigeria (PHCN) which is power bureau of the country, a short circuit calculation was performed studies conducted. The analysis was carried out in two stages, one was using Thevenin equivalent to roughly check unbalance short current from PHCN external source from Kaduna substation at 132/33kV, although this was actually not part of the current studies. The second part was to performed short circuit analysis at network where the windfarm will be connected through 33/11kV level (PCC), which is for this current studies by using computer software tool (DigSILENT powerfactory). This was done to verify the withstands of capacity for the main substation equipment and the new OHLs in comparison with the 3-phase and 1-phase to ground short circuit calculated values of grid studies for the windfarm project. In the network calculation, consideration was made for both maximum and minimum short circuit conditions and it is performed according the IEC 60909 (2001) standards. However, the aim of the analysis was the assessment of the electrical parameters of the WindFarm during and after a three phase short circuit event at the 33 kV Kastina substation because this is the point where the windfarm have to be connected and also the location of the wind generators.
Metalized polypropylene film capacitors (MPPFCs) can work under high electric fields due to the self-healing characteristic. Leakage phenomenon caused by the insulation resistance (IR) in MPPFCs is one of the importan...
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Metalized polypropylene film capacitors (MPPFCs) can work under high electric fields due to the self-healing characteristic. Leakage phenomenon caused by the insulation resistance (IR) in MPPFCs is one of the important factors resulting in the reduction of the energy efficiency. The IR is directly related to the DC electric conduction mechanism in polypropylene film. This paper mainly concentrates on the IR by investigating the electrical conduction mechanism of metalized films under high electric fields. Firstly the conduction mechanism of metallized films is discussed. Secondly IR is obtained under different electric fields based on an established measurement platform The Poole-Frenkel(PF) model presented in this paper includes the field-enhanced carrier density caused by the barrier height attenuation in directions both opposite and forward to the electric field, and the field-enhanced carrier mobility. The equation for electric conductivity based on this model gives not only the usual Ohm's law at low fields but also at extremely high electric fields. And the IR calculations match well with the experimental results.
Stable and fast switching between displacement and pressure will directly affect precision and velocity of automated equipment. Switching control between displacement and pressure, which is based on the velocity dampi...
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Summary form only given. Atmospheric-pressure room-temperature plasma jets are commonly used in plasma medicine, nanotechnology, as well as surface and materials processing. Most of the applications require room-tempe...
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Summary form only given. Atmospheric-pressure room-temperature plasma jets are commonly used in plasma medicine, nanotechnology, as well as surface and materials processing. Most of the applications require room-temperature operation while completely avoiding the glow-to-arc transitions. To meet these requirements, the atmospheric plasma jets are usually sustained in noble gases. However, this is very challenging for the open-air operation. Moreover, the cross-sections of the plasma plumes are typically very small, which make large-area surface processing particularly difficult. One promising way to overcome this shortcoming is by using the plasma jet arrays. However, since the individual plasma plumes generated by the arrayed plasma jets are in most cases independent and do not merge in open air, it is very difficult to achieve uniform plasmas and surface treatment effects. In this paper, we demonstrate a homogenous cold air plasma glow with a large cross-section generated by a direct current power supply. There is no risk of glow-to-arc transitions, and the plasma glow appears uniform regardless of the gap between the nozzle and the surface being processed. Detailed studies show that both the position of the quartz tube and the gas flow rate affect the plasma characteristics. Further investigation indicates that the residual charges trapped on the inner surface of the quartz tube may be responsible for the generation of the air plasma plume with a large cross-section. Moreover, the spatially resolved optical emission spectroscopy reveals that the air plasma plume is uniform as it propagates out of the nozzle. The air plasma plume with remarkable improvement of the plasma uniformity is used to improve the bio-compatibility of a glass coverslip over a reasonably large area. This improvement is demonstrated by a much more uniform and effective attachment and proliferation of human embryonic kidney 293 (HEK 293) cells on the plasma-treated surface.
The interior permanent magnet (IPM) machine with fractional-slot concentrated-windings (FSCW) has become a popular research topic owing to their novel structures and attracting potentials. This paper is focused on ind...
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The interior permanent magnet (IPM) machine with fractional-slot concentrated-windings (FSCW) has become a popular research topic owing to their novel structures and attracting potentials. This paper is focused on inductances and saliency ratios in IPM FSCW machines with different pole and slot combinations. Analytical expressions of inductances and saliency ratios are derived using harmonic analysis method (HAM) and their features and trends are concluded. The concept of dq-axis equivalent windings containing harmonic components is proposed to help better understand these features and trends. It explains the phenomenon that configurations with fewer stator slots and fewer winding layers have lower saliency ratio. Theoretical conclusions are verified by finite-element (FE) method.
We proposed a novel visible polarizer based on multilayer silicon and silicon oxide alternative subwavelength grating and its optical characteristic is numerically investigated by finite difference time domain method....
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We proposed a novel visible polarizer based on multilayer silicon and silicon oxide alternative subwavelength grating and its optical characteristic is numerically investigated by finite difference time domain method. The reflectance of TE mode and transmission of TM mode are above 90% with extinction ratio up to 10 3 . Moreover, the proposed polarizer also has wide angular field and large fabrication tolerance.
A fast π bistable twist nematic (π-BTN) liquid crystal display controlled by nucleation process is developed. The nucleation induced by the patterned spacer inside the cell. The response time is fast and it depends ...
A fast π bistable twist nematic (π-BTN) liquid crystal display controlled by nucleation process is developed. The nucleation induced by the patterned spacer inside the cell. The response time is fast and it depends on the density of patterned spacer.
In order to assess transformer's status and forecast its potential fault, this paper applied Bayesian network classifier into transformer fault diagnosis, combined with dissolved gas analysis and other electrical ...
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In order to assess transformer's status and forecast its potential fault, this paper applied Bayesian network classifier into transformer fault diagnosis, combined with dissolved gas analysis and other electrical test results, and thereby created a transformer fault synthetic diagnosis method. Build up transformer's fault diagnosis model based on Naive Bayesian Classifier and Tree Augmented Naive Bayesian Classifier respectively, and verify their validity by instance.
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