The work reported here, the behavior of intermittent spark discharges in high-intensity acoustical standing wave field was experimentally investigated. A point-point gap or positive-point-plane gap was located at the particle velocity antinode of an acoustical standing wave field, that was produced in a cylindrical acoustic tube. It can be obtained that the luminous part of intermittent spark discharges spread by the effect of high-intensity sound waves; spread to a section of rugby ball-like-shape with a point-point gap and spread to an open fan-like-shape with a positive point-plane gap. The relationship between spread width of luminous part of the discharges and the sound intensity was quantitatively measured and investigated.
As results, the spread width of luminous part of intermittent spark discharges varied in proportion to the amplitude of displacement of sound. It was considered that an air vibration that is particle velocity of sound forces spark discharges to swing and spread to open-shape. An amplitude of swinging spark discharges was in proportion to the particle displacement of sound rather than the speed of particle velocity of sound. The spread width of sparking was approximately 1.3 times as wide as the particle displacement of sound with a point-point gap and 1.7 times with a positive point-plane gap.

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This paper describes an inverse analysis of magnetization distribution in cylindrical permanent magnets used in laser printers and copy machines. The magnetization distribution is reconstructed from the magnetic field measured on a circle outside the cylindrical magnet. The singular system matrix, which maps the inner magnetization to the magnetic field on the outer circle for measurement, is regularized by the Tikhonov method. Test samples of magnetization distribution are computed by the forward analysis of magnetization processes on the basis of the vector Preisach model. The numerical results show good coincidence between the original and reconstructed magnetization. Moreover the regularization parameter is shown to be reasonably determined by the L-curve method.

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Experimental studies are presented on the propagation of an intense pulsed proton beam through a wall-initiated, overlapping, z-discharged plasma channel in the presence of return paths. From the measurements by an image converter camera and a small-sized magnetic probe, we have found the compression of the main channel (or deformation) due to the enhancement of the azimutal magnetic field. Good efficiency of the propagation has been observed. These results seem to give useful suggestions to design a reactor in a future by multiple channels.

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This paper describes the rectangular pulse discharge characteristics of the composite electrodes in N₂ gas. A glass or ZnO contacts with the needle for the needle-plane electrodes configuration. In the case of the glass contacted with the needle, the discharge voltage increased with increasing L (the distance from the tip of a needle to the dielectric). In the case of ZnO contacted with the needle, the discharge voltage increased with increasing L from 0mm to 2mm, but it gradually decreased with increasing L from 2mm to 10mm. It is considered that these differences on the discharge voltage characteristics originate from the corona extension process and discharge path.

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The paper describes the calculation results of electrostatically induced current in a human model. The calculation method is the boundary element method (BEM). The human model was constructed from the second order curved elements. Five intenal organs were added to the model in order to investigate the effect of differences in conducivity values. The calculation results show that there is no effect of conductivity in the calculation of overall induced current. We have confirmed that the overall calculated induced current is about 15% higher than the empirical expression given by the EPRI. If we keep the height of the human model constant, 10% change in size of the model results in about 5.5% change in the overall induced current. The induced current was found almost uniformly distributed on each z cross section. In the human model with the internal organs, conductivity of internal organs exhibits considerable effect on their induced current. We have shown that the induced current in an organ varies proportionally to the ratio of its conductivity to the surrounding conductiviy if it is located separately from the other organs. We have compared induced electric field in an organ with an analytical solution in the arrangement of an ellipsoid in a uniform field. The difference between the analytical and numerical values is very small in the liver and intestine. However, the field distribution in the heart and lung varies so much along z-direction that the analytic solution is not a good approximation.

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Studies on the shielding factor against the transverse magnetic field have been carried out but that against the axial (longitudinal) magnetic field is less studied. Moreover, the maximum magnetic flux density in magnetic materials of the shield is not evaluated up to the present.Applying existing approximate expressions for the shielding factor, approximate expressions for the maximum magnetic flux density were derived for single and double cylindrical magnetic shields. In order to evaluate the accuracy of the expressions, the linear finite element method (FEM) was used to calculate the shielding characteristics of shields with different length and thickness. The calculated results by both the FEM and the approximation agreed considerably in the case of the single cylinder but the agreement was obtained only within the limited shield dimensions for the double cylinder.

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This paper describes a computer simulation study for estimating the multiple sources in the brain based on a three dimensional measurement of magnetoencephalogram (MEG). We proposed a new method of estimation algorithm using spatio-temporal data of MEG and singular value decomposition analysis. The number of estimation source is decided by number of dominant singular value of spatio-temporal MEG data. The source localization is done as pattern matching by signal subspace of singular vectors and projection of an estimating source. The results show estimation errors with the phase difference and the distance of two dipole sources. This proposed method can estimate two sources, which are more than 2cm apart and 15 degree phase difference. We conclude this method is useful as multiple source estimation.

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Cylindrical polypyrrole (PPy) fibers were electrochemically polymerized in a Teflon slender pipe. The PPy fiber could be cut into small rectangular strips and the strips were electrochemically characterized. The PPy strip can be used as an actuator, because a bending behavior was observed during oxidation/reduction cycles. That is, the strips bend toward the outer surface, which contacted with the Teflon pipe during polymerization, upon reduction, and revert upon oxidation. We have investigated the bending behavior of the PPy actuator in various electrolytes and have found that incorporation of cations into PPy upon reduction plays a key role in the bending behavior. A mechanism of the bending behavior based on the cation incorporation as well as the anisotropic volume change upon doping is proposed.

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Biomagnetic signals are very weak compared with those of the environment magnetic field due to train and motor car. The train especially the direct-current electric railcar is seemed to be one of the main urban magnetic noise sources at low frequency in Japan, by comparing the fluctuation of magnetic field at the day when there are many trains with that at the night when there is no train. In this paper, first, the relationship between the environmental magnetic field and the electric current of the direct-current electric railcar of the personal track was discussed. Second, the fluctuation of magnetic field was calculation from that of the unbalanced electric current between feeder line and railroad, which could be obtained as the leakage electric current to the ground. The validity of calculation was verified by comparison with measurements.

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A simple structured liquid pump based on the electrohydrodynamic flow was developed. The structure of a developed pump is a plastic pipe with electrodes on the both sides. The needle electrode partially covered with a plastic film forms the anode and the disc electrode with a hole at the center forms the cathode. The hole is connected to the outlet tube. Though the field of application of this pump is limited, as it is only workable in the insulating oil under high D. C. voltage, its structure is so simple that it is easily fabricated and the multiple configuration is straightforward to increase the power.

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It is well known that color appearance depends on the visual environments. In this experiment, Apparent color and hue-shift in the small visual angles were investigated quantitatively employing the color-matching method. Four observers with normal color vision and visual acuity participated in this experiment. The results showed that Munsell Chroma decreased, on the other hand, Munsell value increased as the decrease of the visual angles. Namely, color perception shifted from chromatic color to achromatic color. We are confident that in the visual environments involving small visual angles, these results are useful both for the basic study and for the practical applications.

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Fullerene thin films were prepared by conventional vacuum evaporation deposition and by ion plating with no bias, +200 V and -200 V bias applied. Weak C₆₀ (420) and (664) peaks were detected from X-ray diffraction patterns of all the films. Transmittance spectra showed that the transmittance of all the films was more than 95% in the infrared region, whereas there were some broad absorption spectra at 221, 271, 347 and 476 nm. The shape of the absorption spectra for the films prepared with no bias and -200 V were similar, and weaker and broader than those prepared by evaporation deposition. The spectra for the prepared with +200 V became much weaker and broader.

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This paper proposes analytic expressions of the potential and electric field generated by a triangular surface charge which uses a second-order function for representing the charge density on the element. These expressions are applicable to the surface charge method in electric field calculations. In general the high-order charge density improve the calculation accuracy.

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