This article presents the dynamic simulation of dielectric particles under an electric field. A multipole model including multipolar interactions between particles is used here to calculate an electric field on the particles and then the force from the electric field. The simulation has been performed on the systems of an ER fluid having different volume fractions. The simulation results by the multipole model have been compared to those by the dipole model, which is often used in the existing works. The comparison shows that, for the system of very low volume fraction, the particles bridge the electrodes faster by the multipole model than by the dipole model. For the systems of higher volume fraction, the aggregation of the particles depends greatly on their initial positions. The results also show that, in a real ER fluid, the ordering of the particle chains may not be parallel well to the field direction as that predicted by the dipole model.

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The purpose of this paper was to investigate the preventive effects and long term effects of extremely low frequency pulsed electromagnetic fields (PEMFs), generated by circular coils and pulsed electromagnetic fields stimulators, on osteoporosis in bilaterally ovariectomized rats. In preventive experiment, thirty three-month old female Sprague-Dawley rats were randomly divided into three different groups: sham (SHAM), ovariectomy (OVX), PEMFs stimulation (PEMFs). All rats were subjected to bilaterally ovariectomy except those in SHAM group. The PEMFs group was exposed to pulsed electromagnetic fields with frequency 15 Hz, peak magnetic induction density 2.2mT and exposure time 2 hours per day. The bone mineral density (BMD) of vertebra and left femur were measured by dual energy X-ray absorptiometry at eighth week, twelfth week and sixteenth week after surgery. In long term effects experiment, forty four rats were randomly divided into sham (14 rats, SHAM), ovariectomy group (10 rats, OVX), 15Hz PEMFs group(10 rats, 15Hz) and 30Hz PEMFs group(10 rats, 30Hz) at twenty-sixth week after surgery. Rats in PEMFs groups were stimulated sixteen weeks. In preventive experiment, the Corrected BMD of vertebra and femur was significantly higher than that of OVX group after 16 weeks (P<0.001, P<0.001 respectively). In long term effects experiment, the vertebral BMD of 15Hz PEMFs group and 30Hz PEMFs group was significantly higher than that of OVX groups (P<0.01, P<0.05 respectively). The experimental results demonstrated that extremely low intensity, low frequency, single pulsed electromagnetic fields significantly slowed down the loss of corrected vertebral and femoral BMD in bilaterally ovariectomized rats and suggest that PEMFs may be beneficial in the treatment of osteoporosis.

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Time-resolved probe and optical emission measurements were performed in the pulse modulated microwave oxygen plasma that was produced using a ring-slot antenna for surface wave mode. Microwave power (2.45 GHz, ˜1 kW max.) was modulated with a square wave pulse of 100 μs period and 20˜90 % duty ratio. Spatiotemporal evolution of an electron energy distribution function was obtained and the optical emission actinometry was used as a means for estimating relative concentrations of radicals in the plasma. These characteristics were compared with those of the continuously driven (CW) plasma.

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At present line and apparatus composite insulators are widely accepted for use on AC overhead lines and in high voltage substations. The present paper concentrates on measurements of different pollution parameters of naturally exposed apparatus composite insulators tested at five different sites covering coastal, tropical and semi-desert environments. In general all tested silicone rubber apparatus insulators (for the period from 1 to 8 years) performed well. However, the difference in pollution layer is evident even for the sites formally belonging to the same class, e.g. coastal sites. The standard parameters, ESDD/NSDD are not enough to understand and proper evaluate the pollution performance of composite insulators. It is suggested to use the Wettability Class (WC) and Hydrophobicity Transfer (HT) tests in addition to the standard parameters.

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Non-equilibrium plasmas under atmospheric pressure are of great interest in polymer surface processing because of their convenience, effectiveness and low cost. In the present work polyethylene terephthalate (PET) film surface is modified using the non-equilibrium plasma generated by the atmospheric pressure glow discharge (APGD) and dielectric barrier discharge (DBD) in ambient air. The differences in discharge characteristics between APGD and DBD are shown by measurement of their electrical discharge parameters and observation of light-emission phenomena. The effects of APGD and DBD on PET surface modification are studied by comparing their surface properties, which are characterized by contact angle measurement, X-ray photoelectron spectroscopy (XPS) and scanning electronic microscopy (SEM). It is found that the APGD is quite homogeneous and stable in the whole gas gap, which differs from the filamentary micro-discharge of the DBD. It is concluded that the APGD and DBD treatments modify the PET surface in both morphology and composition, but APGD is more effective in PET surface modification than DBD as it can modify the surface more uniformly and make the contact angle decline to a lower level.

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Discharge characteristics in single-phase equipment are a well-known and well-established art, however, those in three-phase equipment are far less understood. Because the electric field in the insulating material of three-phase equipment is not linear, but rotates with power frequency, it can be expected that the discharge characteristics in three-phase equipment will be different from those in single-phase equipment. In this paper, the effects of rotating electric field on partial discharge pattern in a three-phase construction are reported. The simplified model of a three-phase GIS with air inside is used. The electric field in the construction was analyzed, and the discharge characteristics were observed. The electric field vector locus in a three-phase construction is elliptical, although the shape differs locally. The elliptical nature of rotating electric field is expressed as an electric field ratio. The experimental results showed that the phase widths where partial discharge current pulses appeared were different depending on the electric field ratio even for the same applied voltage. The phase width where partial discharge current pulses appeared was also influenced by the applied electric field. These results are analysed from the relationship between the value and the locus of the applied electric field and the critical electric field of air.

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An electrohydrodynamic (EHD) pump is one of the non-mechanical pumps and expected to be utilized in various micro-pumps. The EHD pump driven by an electrostriction force is expected to reduce power consumption rate and degradation in insulation property of the working fluid. We have investigated electrode structures of the EHD pump, where the electrostriction force works as a main force, by using electromagnetic and fluid dynamics simulations. The numerical results showed that ring and plate electrodes could drive the fluid efficiently with the electrostriction force. We have measured characteristics of the EHD pumps using a cyclic flow path and compared these experimental results with the simulation data. We also analized three-rod structure by the numerical simulation to be applied as miniaturized EHD pumps.

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It has been reported that the experimental investigations on the synchronization probabilities of the two surface streamers in atmospheric air by the authors. This synchronization phenomenon is interpreted by following processes. When an impulse voltage is applied to the parallel connected electrodes, a prior streamer occurs and the propagating streamer emits light. This light passes through the air and reaches the other electrode area. In this area, the initial electrons are supplied by the light and the initial electrons trigger the second streamer. The wavelength region of the light effective for the synchronization was confirmed experimentally. The region was shorter than 250 nm but the detailed wavelength cannot be specified by the experiments. Accordingly, as the first step to specify the effective wavelength, VUV emission spectra from DC positive corona discharges in air are observed together with nitrogen and oxygen gases. Several strong line spectra emitted from the discharges in air are recognized. They are identified that the emission lines of 174 nm, 149 nm and 118 nm are radiated from atomic nitrogen. On the other hand, the emission lines of 120 nm and 130 nm are originated from atomic oxygen. The preliminary experimental results show that these lights are absorbed immediately in air, so on-site photoabsorption measurements were carried out in air. The absorption coefficients of the air are estimated in this study. Even if the wavelength of the light is in the region of VUV, the light can pass through in the air. The facts suggest that the VUV light can pass through long distance in air and the light is effective for the propagation and the synchronization of streamer discharges through the photoelectron emission.

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Low work function is a vital life-determining characteristic of fluorescent lamp electrodes. The work function of a fluorescent lamp electrode increases due to the loss of Ba atom from the electrode. Hence the rate of Ba atom loss controls the lifetime of the lamp. However the loss mechanism and the optimum discharge condition has not been well understood yet. In the study, the loss of Ba atom from a fluorescent lamp electrode using a laser-induced fluorescence (LIF) technique is investigated. The lamp was operated at both AC 60 Hz and DC discharge modes with different discharge currents. In addition, the electrode of fluorescent lamp was connected through an external DC current source to control the electrode temperature. The effects of both the discharge current and the electrode temperature on the emission of Ba atom were investigated. For the lamp operation at 60 Hz, the physical behavior of the emission of Ba atom from the anode and the cathode were found to be different. The most of the loss of Ba atom was observed in an anode half-cycle, while this loss was lower in a cathode half-cycle. In the case of DC discharge, with increase in the discharge current, the loss of Ba atom was increased at the anode while it was decreased at the cathode. At the cathode the decrease in temperature was due to the electron emission from the cathode, which is called as “electron cooling” and it played an important role for the suppression of the Ba atom loss. Additionally, the sputtering of Ba atom due to ion bombardment was also considered to be an important factor for the loss of Ba atom from the cathode at a low discharge current.

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Application of MgO to electrodes of the liquid crystal display back-lighting source was investigated. The breakdown voltages in the case of MgO electrodes were measured under various Ne pressures with a V-Q Lissajous method. In order to measure the breakdown voltages in Ne, the samples tested were MgO single crystal plates of polished surface and non-polished surface, and MgO sintered ceramic plates. The breakdown voltage in the case of MgO single crystal plates of non-polished surface was lower than that in the case of MgO single crystal plates of polished surface. The breakdown voltage in the case of MgO sintered ceramic plates was slightly lower than that in the case of MgO single crystal plates of non-polished surface.

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This paper presents experimental results of NO removal from a simulated exhausted-gas using a barrier type reactor with screw electrodes subjected to polarity-reversed voltage pulses. The polarity-reversed pulse was produced by direct grounding of a charged coaxial cable because a traveling wave voltage was negatively reflected at the grounding end with a change in its polarity and then it propagated to the plasma reactor at the opposite end. Influence of cable length on NO removal was studied for two kinds of cable connection, single-connected cable and parallel-connected cables. NO removal ratio for a 50m-long cable was lower than that for much shorter cables in both single and parallel connections when the applied voltage became high. Energy efficiency for NO removal also increased with decreasing the cable length. This was because excess discharges during the voltage oscillation caused by the large stored energy in the long cable resulted in reproduction of NO molecules. Energy efficiency was further improved by changing the discharge mode from dielectric barrier discharge (DBD) to surface discharge (SD). Energy efficiency was up to 110g/kWh with 55% NO removal ratio and 34g/kWh with 100% NO removal ratio by using a single 10m-long cable in SD mode.

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This paper describes an improvement of NO removal efficiency using dielectric barrier discharge (DBD) ozone injection system, with focusing comparison with a conventional plasma remediation system and effect of electrode configuration employed in the DBD reactor. Ozone was generated in the DBD reactor, and was fed to an oxidizing chamber to convert NO into NO₂. The experiments were carried out with applying sinusoidal voltage of 10 kHz. Nitrogen, oxygen, and NO gas with concentration of several hundreds ppm was used as simulated gas of a diesel engine exhaust gas. For ozone injection system, we obtained the 18-g/kWh energy yield close to well-known 20 g/kWh. However, for the conventional plasma remediation system, we obtained the 10-g/kWh energy yield lower than well-optimized DBD reactor. Under well-optimized conditions, there was little difference in energy yield between the ozone injection system and the conventional plasma remediation system. On the other hand, the ozone injection system was also effective under unoptimized conditions. The electric fields of the needle-type electrodes were strongly distorted in spatial distribution, as a result, it caused the low-voltage operation and the dielectric loss compared with the plane electrode. The pyramid projection height was not dominant factor for the DBD reactor performance.

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