The applicability of LED light sources to detection of thermally grown oxide (TGO) layer in thermal barrier coating (TBC) for gas turbines was evaluated. A green LED of center wavelength 540 nm was found to be more efficient than a blue LED of center wavelength 460 nm to excite Cr³⁺ in the TGO layer. Using the green LED, photoluminescence was observed at 694 nm for TBC specimens heated at 1100°C. The dependence on the heating time was the same as the case of laser excitation. Using a green LED light source with higher power, photoluminescence was also observed for specimens heated at 1000°C. The results indicated that an inexpensive TGO detection system can be constructed using LED light sources.

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We developed a compact susceptometer employing a high-temperature superconductor (HTS) superconducting quantum interference device (SQUID) that can measure M-H characteristics and harmonic components induced in the AC magnetic field response from a sample. In the DC function for measuring M-H characteristics, the sample was vibrated in the DC magnetic field, and the secondary magnetic field generated from the sample was detected by a DC pickup coil. In the AC function for measuring harmonic components, the sample is placed in the AC magnetic field, and the AC response was detected by an AC pickup coil. The pickup coil is connected in series with the input coil, which is inductively connected to the HTS-SQUID. Signal from the HTS-SQUID was transmitted to the lock-in amplifier, and was analyzed as the intensity and phase of the measured magnetic field. In order to clarify the basic properties of the system, we measured the AC magnetic field response from a sample in the case of changing the position between the sample and the pickup coil, and M-H characteristics when changing the DC bias magnetic field intensity. Furthermore, by analyzing the harmonic components of AC/DC magnetic field response, the system is able to measure the magnetic properties with high sensitivity and high speed.

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Time-resolved reflection measurement using broadband, short terahertz pulses can provide cross-sectional images of dielectric materials at different depths. Low frequency components which have responses over a wide time range may result in inclusion of spurious signals which arise from strong reflections at other depths. Model calculations showed that such spurious signals can be suppressed by application of a frequency filter of appropriate center frequency. The effect of frequency filtering was investigated in cross-sectional imaging of an IC card. Cross-sectional images were obtained at depth intervals of 0.18 mm, which provided images at 5 different depth intervals. As a result of frequency filtering, spurious images resulting from strong reflections at different depths could be reduced in intensity, which resulted in improvement of the measurement resolution of the depth distribution.

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We investigated method to osmose water and seasoner to dried soybeans faster by pulsed electric field, in order to make soybeans a processed food faster. By applying the pulsed electric field to the dried soybeans in water, osmosis time of water to the soybean became approximately half. Then the emission of the discharge was observed on and in the dried soybean. This phenomenon shows that electroporation was occurred at the cell wall and the cell membrane of the soybean. The color of soy sauce permeated more into the soybean applying the pulsed electric field than no-applying it to the dried soybean in water. Permeability of soybean for soy sauce wasn't improved by applying the pulsed electric field to rehydrated soybean. However uniformity of the coloring by soy sauce was improved by applying the pulsed electric field before and after rehydrating to the dried soybean.

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Biological and medical field as sterilization with pulsed electric fields or discharges and electroporation have been studied actively in recent years. It is clear that the pulse electric fields bring some sort of influences to organism. But for now, it is not sufficiently clear what influence appears and how mechanism works on the organism by the pulsed electric fields.  The effects of pulsed electric fields on manifestation of RNAs in biological cells were studied with a goal to figure out the mechanism of bioelectrics. The pulsed electric fields were applied to Vibrio parahaemolyticus as pathogenic bacteria and the manifestations of RNAs: TDH, VP1680 and VP1699, which specify pathogenic agents, were analyzed with method of PCR. The manifestation levels of VP1680 increased with the application of pulsed electric fields, and the effect was distinguished when the electric field strength was 14 kV/cm. The electric field strength barely affected the manifestations of TDH and VP1699. It was found that the effects of electric fields were different among RNAs. The manifestation level varied with time when the manifestations are analyzed. These results suggest a probability of selective control on gene expression by pulsed electric fields and new applications such as a development of functional food.

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Recently, as a great demand for high-strength and high-hardness materials is rising, improvement in performance of tools which manufacture those materials is being needed. Generally, tools to manufacture such materials are given high-hardness coating. Diamond and DLC (diamond like carbon) film are regarded as typical high-hardness materials, though, they can't be given to iron tools because carbons contained in them have high reactivity to iron. Consequently, the boron-nitride film which doesn't contain any carbons is expected as a coating material which can be adapted to iron tools. In this research, we prepared boron-nitride thin films on Si substrate using RF plasma CVD (chemical vapor deposition) method apparatus with a gas mixture of argon, nitrogen and trimethylborate (TMB: B(OCH₃)₃).

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Utilizing a high power discrete SiC-JFET developed by KEK, a switching power supply (SPS) that had a circuit topology of H-bridge was designed and constructed to drive the induction acceleration system for the KEK digital accelerator. Firstly, the SPS was operated with a 38Ω dummy resistance load and bipolar outputs of 800V and 21A were successfully demonstrated at 1MHz. Nextly, combination test with an actual induction cell was demonstrated. And finally, actual beam acceleration test was successfully demonstrated.

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Effect of secondary electron emission coefficient on dielectric barrier discharges in atmospheric pressure oxygen has been simulated using two dimensional fluid model. The discharge characteristics were significantly affected by the secondary electron emission coefficient. With decreasing the coefficient, many peaks in the discharge current waveforms were obtained and number of filament discharges decreased, but the surface discharges significantly extended. And it was found that with decreasing the coefficient, there is a minimum on ozone generation rate curve.

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A planetary type magnetic gear consists of coaxial inner and outer rotors with surface-mounted permanent magnet, and ferromagnetic stationary parts called pole-pieces. It offers desirable features which conventional mechanical gears do not have, such as low maintenance and acoustic noise, and inherent overload protection. This paper presents a comprehensive study of the influence of geometry and position of the pole-pieces on torque performance based on finite element analysis (FEA) and experiments. Surveyed parameters of the pole-pieces include lengths in radial and axial direction, width in circumferential direction, and position in radial direction. Finally, it is demonstrated that the maximum torque of the improved prototype gear is increased by 45% and the maximum efficiency achieves up to about 99%.

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We have tested orthogonally stacked figure-of-eight flexible coils to detect the rotation angle of a rotor made of the grain oriented silicon steel. In this scheme, an angle between the axis of the uniaxial anisotropy pertaining to the rotor and the prefixed axis of a flexible coil is related to the orientation dependent permeability. A 15 mm by 15 mm size flexible coil is placed closely to the rotor and the other side of the coil is covered with an amorphous tape working as a back yoke. One of the figure-of-eight coils is used as an excitation coil and the other is for a sensing coil of magnetic fluxes passing through the rotor. With an excitation current of frequency 16 kHz and 50 mA, a demodulated output of a sinusoidal waveform under the constant rate of revolution of 3000 rpm was obtained with a rotor of 7.6 cm in diameter. The scheme was further developed to obtain two phase outputs by combining two sets of the flexible coils, where coils in one group is 45 degree angle rotated from those in the other group. Basic characteristics of a developed axial resolver were investigated.

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To locate partial discharges (PDs) in cross-bonding cables where current pulses due to PDs might be divided, we paid attention to phases of current pulses obtained by six CT sensors arranged at both sides of 3-phase of the cables. The accuracy of PD location, obtained by using time difference between arrival times of current pulses from specified phase, was relatively high even for cross-bonding cables.

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Compact pulsed power generator was developed to improve a mushroom yield and was evaluated in effect on the yield. To reduce the high-voltage generator size, Cockcroft-Walton circuit was employed. The pulsed power generator consisted of rechargeable dry cells, control unit, transformer, Cockcroft-Walton circuit, 2 m-length coaxial cable and gap switch. The maximum output voltage of the generator was 100 kV with several microseconds in pulse width. The weight of the generator was several kg which was capable of carrying the generator on farmer's shoulder.

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Residual voids in degassing process of encapsulation gel for a power device limit the lifetime and the performance of the device itself because of the partial discharges occurrence in it. In this paper the limit of the degassing capability is evaluated based on the equation of equilibrium. It turns out that the gas in defects such as holes and cracks at the rim of the chip-mounted electrode on ceramic substrates cannot be completely removed by vacuum degassing. Then the size of voids that are likely to form in defects is also calculated with a simple model. This analysis is also experimentally checked with a pierced PMMA plate. The measured results can be explained well by the above mentioned model.

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This paper describes an analysis of the effects of transient electromagnetic fields on bioelectric potential responses of plant leaves. In our experiment, a single transient electromagnetic field was periodically applied to aloe and pachira for 3 days. The pulse application cycle was set to 1 time per 1 day with charging voltage of 20kV. After the pulse application, we measured bioelectric potential of target leaves for 12 hours. As a result, we found that bioelectric potential energy was increased by application of transient electromagnetic fields.

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[in Japanese]

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