In the case of charge distribution measurement on an insulating material using an electrostatic probe, an inverse calculation from the probe output to the charge distribution is inevitable, because the probe output is influenced by the surface charges on the entire surface of the measured object. Signal-processing techniques have been adopted to improve the stability of such inverse calculation. The spatial resolution of measuring system is discussed in terms of the transfer characteristics in spatial frequency domain.

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Since gas-insulated switchgear (GIS) is subjected to very fast transient overvoltages such as lightning surges or disconnector switching surges. Therefore the sparkover voltage and time (V-t) characteristics of SF₆ in a very short time range of less than 1μs are of great interest from the viewpoint of insulation design and coordination for a GIS. This paper describes the V-t characteristics of SF₆ at a gas pressure of 0.5MPa using a steep-front square impulse voltage under a quasi-uniform field gap and presents a quantitative evaluation of the V-t characteristics for a nonstandard lightning impulse voltage. In the case of a square impulse, the V-t characteristics of positive polarity were observed to be almost flat over a long time range from 80ns to 10μs, and rose steeply over a short time range from 80ns down to 20ns. For negative polarity, the V-t characteristics exhibit a gentle rise from 200ns down to 40ns. In the estimation of V-t characteristics, the equal-area criterion parameters were quantitatively estimated using the square impulse. For a nonstandard lightning impulse, we found that the application of equal area criterion with these parameters for the non-oscillating impulse and oscillating impulse of up to 5.3MHz as a model of lightning surge and disconnector switching surge is possible.

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Detection of shallowly buried landmines using ground penetrating radar (GPR) signals is studied. Detector employed here is designed by using hidden Markov models (HMMs) to characterize the sequential information in GPR signals. In order to check the performance of the detector, it is applied to example data calculated by using a two-dimensional FDTD method. Detection performance is presented for receiver operating characteristic (ROC) curves. The results show that good detection performance is obtained even for landmines buried at shallow depths under a rough ground surface where the responses from the landmines and those from the ground surface overlap in time.

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In this paper, a theoretical analysis of an equivalent resistance of an eddy current displacement sensor is described. The AC resistance becomes lager due to the influence of the skin effect and the proximity effect when the operating frequency of the sensor becomes higher. The equivalent electronic circuit of the eddy current displacement sensor is composed of inductance, resistance and parasitic capacitance. The inductance was calculated by using the theory of Dodd. When calculating the resistance, both skin effect and proximity effect were taken account of. The parasitic capacitance was estimated by using the experimental results. The equivalent resistance of the eddy current displacement sensor was calculated by using them all. Through experiments, we confirmed that the calculated equivalent resistance well accorded with actually measured one.

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This paper describes an effective analysis of magnetic shielding based on homogenization. The analyses become time-consuming if the problems include the magnetic substances having fine structure. The homogenization of the structure makes it possible to analyze effectively the magnetic fields. The authors introduce a method to estimate the effective permeability of the homogenized substance. This method can be applied to any periodic structure made of magnetic substance. The magnetic shielding effects by the structures against direct-current (DC) fields generated by electric railways are analyzed by using the present method. As a result, it is found that the overhead way and the protective fence near the railway work as a magnetic shield, whose effects can be improved by appropriate arrangement of those constructions.

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The three dimensional optical technique has been applied to analyze the experimental results relating to the magnetic wave scattering phenomena. Recently, we have developed an ideal equation for analyzing the three dimensional transmittance character of light scattered due to many index-ellipsoids. The index-ellipsoids are arranged directly along the light axis in series. In this case, the size of index-ellipsoid and the gap distance between each index-ellipsoid and neighbor one are considered as a calculation condition. By using an analyzing equation devised by us, we have tried to find out the condition under which the light can be passed trough many transparent mediums with high efficiency. From the numerical calculations, we succeeded to look for the condition the maximum transmittance of light 100% is obtained when a spherical and elliptic index-ellipsoids are alternately arranged each other.

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In the measurement of discharge characteristics of a gas in a controlled condition, such as under pressure, the electrodes are set up in a pressure vessel. This often makes a deficiency of initial electrons between gaps, resulting in increase of statistical time lag and dispersion of discharge voltage. We apply irradiation of UV light ore radial rays with a radioactive isotope as an artificial method of supplying initial electrons. In UV light irradiation, initial electrons are emitted from the electrode surface by photoelectric effect, which is irrelevant to the kind of a gas under study. The radial ray irradiation, on the other hand, generate electrons by ionizing gas molecules (Compton effect), which makes it important to understand the effect of the gas on the generation of initial electrons. In this paper, the ionization current of SF₆, CO₂ and N₂ was measured using ⁶⁰Co as a radioactive source. The charged particle production rate was estimated from this result. Moreover, the number of the charged particle which can become an initial electron is described.

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It is difficult to analyze the effectiveness of shielding sheets theoretically and to derive numerical values which are close to the measurement values. When calculating a numerical values, we have to consider the location of the observation point, because the distance from the source is sufficiently small in comparison with the wave length. In this research, we used a small electric dipole as the source and measured the shielding effectiveness (SE) with a shield box. For the numerical analysis, we modeled the material and shield box as thin homogeneous layers. Then, for calculating the electromagnetic field, we used the Sommerfeld integral that expresses a spherical wave as a composition of cylindrical waves. Using this numerical calculation, we estimated the relative dielectric constant of liquid materials. We evaluted the estimated electric parameters of liquid materials, comparing them with nominal values.

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Recently, the pollution of the soil by heavy metal elution from industrial effluents and so on becomes serious with the development of the industry. Until now, many techniques such as diffusion prevention and elution prevention, extraction and removal, decomposition and decontamination have been proposed in the method of processing of polluted soil. In recent years, especially the method for using the electrokinetic phenomenon is noticed. In this method, the paired electrode is inserted in the soil, and the DC voltage is applied. Then, the electrokinetic phenomenon by the procedure of the superscription, namely electrophoresis, electroendosmose, electrolysis, is utilized.
However, in the conventional research, recovery quantity of the heavy metal ion is low, and the improvement in the recovery efficiency is desired in order to use this technique for the repair of the polluted soil. Following fact is mentioned as the reason why the recovery efficiency of the heavy metal ion lowers. When the heavy metal ion has moved from the anode to the cathode, it combines with hydroxide ion made by the electrolysis of the water at the cathode, and it has precipitated as a hydroxide. The purpose of this study is prevention of the alkalinization by adding the acid at the proper quantity, and improves the recovery efficiency of the heavy metal ion.

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Intermediate transfer belt plays a very important role in electrophotographic devices like color printers and copying machines to transfer the toner from the photoconductive roll to the paper. Polyimide film mixed with carbon powder is often used as the material of the belt. The toner is attached by electrostatic force. However, the transcription mechanism has not been investigated sufficiently. We examined the mechanism by the observation of space charge behavior under dc voltages. A significant space charge was observed in the vicinity of the front surface on which the toner is attached in the practical device. This would enhance the electric field on the surface and consequently upgrade the transcripting performance. The surface resistivity was higher on the front side than the rear side, leading to the formation of large space charge in the vicinity of the front surface. Three dimensional space charge measurement showed that sectional distribution of surface resistivity strongly influences on the formation of the space charge and determines the quality of the printout. The intensity of the space charge became larger with increasing dc voltage, however, dielectric breakdown took place when the voltage was extremely high. It is recommended that the applied voltage across the film should not be higher than the region in which the leakage current rapidly increases. Ion analysis showed the existence of organic acid, suggesting that the space charge was formed as the result of its dissociation.

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The present work is dedicated to the problems of synthesis of stop-band structures based on non-uniform transmission lines (NTL) with parameters distributed periodically or quasi-periodically along the axial coordinate. The parameter variation is achieved by changing the structure geometry or medium properties. The subject mentioned is considered with relation to standalone filter design as well as to a problem of improving a transmission medium in such a way that this medium has properties of a stop-band filter. The problems of optimization of NTL structure are studied with the aim of obtaining maximum stop-band in the given frequency range. Based on the investigation of periodical structures the resonant conditions for different ways of parameter variation are developed. It is shown that due to changeover from the periodical structure to a quasi-periodical one it is possible in a number of cases to widen the initial stop-band obtained for the periodical structure. The genetic algorithm is used to obtain the optimal nonuniformity distribution along the line.

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It is important to grasp the reflectivity of EM wave absorbers in millimeter waves by rapid progress in a recent utilization of the frequency. A Free Space Method with horn antennas is in widespread use for the reflectivity evaluation of EM wave absorbers. In this paper, we investigate a Free Space Method that can evaluate accurately the reflectivity of EM absorbers in millimeter waves. We present the fundamental data and conditions for a Free Space Method to evaluate accurately the reflectivity of EM absorbers in millimeter wave. Moreover, the reflectivity of dielectric materials (e.g., quartz glass, single crystal sapphire) with a uniform constant is measured. As a result, the validity of a Free Space Method in millimeter waves is confirmed by comparing the evaluated characteristics of dielectric materials to a theoretical value.

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It is well known that the degradation of XLPE cable by water tree gives rise to harmonics in the loss current. Many researches by simulation and experiment have been carried out for the purpose of the elucidation of the mechanism of the harmonics in the loss current generation. In the present study, the loss current was calculated from the equivalent circuit model composed of voltage-dependent resistance and condenser. These elements are being connected with the matrix state.
As a result, we were able to obtain the good agreement between the experimental value and the calculated value by appropriately choosing the characteristics of the voltage-dependent resistance. The equivalent circuit model determined in this study can consider not only the electrical characteristic of water tree but also its shape.

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Organic thin films such as Alq₃, TPD and PVCz used for an organic electroluminescence (OEL) devices were prepared by pulsed laser deposition (PLD) technique using one of fundamental (λ=1064 nm) or second harmonic (λ=532 nm) of a Nd: YAG laser and a KrF excimer (λ=248 nm) laser. Both Alq₃ and TPD films deposited by using Nd: YAG laser showed photoluminescence (PL) spectra similar to those of the targets, which have peaks of 525 nm and 420 nm, respectively. However clear PL could not be seen in the films by KrF excimer laser. Structural compositions of the Alq₃ and TPD films depended on the laser wavelength. According to photon energy of a laser light, deposition process using Nd: YAG laser were dominated by the thermal effect, while the process using KrF excimer laser was influenced by a photochemical reaction.
NVCz films were grown by pulsed Nd: YAG (532 nm) laser deposition method using the monomer NVCz target at the laser fluence of 300 mJ/cm². The NVCz films had absorption spectra indicating the polymeric molecular structure similar to the spin-coated PVCz film. This research suggests the possibility of the polymer film formation using PLD process without heating and the initiator.

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We have investigated the contribution of the oxygen ions and electrons on oxygen plasma treatment of Indium Tin Oxide (ITO) electrode for organic solar cell (ITO/CuPc/C₆₀/CuPc/Al). The cell characteristics were markedly improved by the treatments using positive oxygen ions and electrons. In the case of the treatment by positive oxygen ions, short-circuit photocurrent density increased markedly. The enhancement of photocurrent was explained in terms of a lowering of total resistance between CuPc layer and ITO due to an increase in work function and a stacking with high orientation in CuPc molecular configurations during the grow process. In the case of the treatment by electrons, on the other hand, fill factor showed a high value (about 0.5). However, further studies are needed for confirmation of this phenomenon.

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The water treeing phenomenon has been recognized as an ultimate difficulty for long-term service life of cross-linked polyethylene (XLPE) insulated power cables. Elucidation of substantial mechanistic pathway of water treeing is quite important to suppress water treeing. Many factors which affect water treeing have been found, such as electrical stress, existence of water, temperature and mechanical stress, and somewhat complicated synergestic interaction between them has also been pointed out. These factors make water treeing very difficult to be understood.
The author studied the role of water in this phenomenon. To obtain certain analogical evidence for water treeing, a series of experiments was conducted by employing, as substituents of water, several organic solvents which possess relatively high dielectric constant and dissimilar electrochemical behavior, respectively.
Consequently, it was found that a new type of treeing in XLPE matrix could be generated by certain organic solvent without water, and such treeing became easier to incept and propagate when the solvent contained particular electrolyte. Further, it was also indicated that cation was more effective than anion on such solvent treeing. Water tree inception and propagation mechanism was discussed from these experimental results.

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Wrong:the power facter
Right:the power factor

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Wrong:sperical Tokamak
Right:spherical Tokamak

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Wrong:Toyota TechnoIogical Institute
Right:Toyota Technological Institute

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