We propose theoretical formulation to connect the integral equations of conductor currents and differential equations of displacement currents in order to develop analytical techniques related to high-frequency electrical characteristics for noise and surge protection designs. Discretization of the obtained equations by the finite element method leads to only one matrix equation of 3D space and second-time derivative with the unknowns of current vector potentials because the displacement currents can be eliminated. In the frequency domain, the frequency characteristics of displacement currents in insulators and currents in conductors as well as impedances can be obtained with this method. To verify this method, we developed a 3D high-frequency currents calculation program. We calculated the impedances of test objects, and compared them with our measured impedances. The results were as follows. (1) The calculated resonance and anti-resonance frequencies of a simple 1D transmission line were within a 4.5% difference off measured ones below 1GHz. (2) The first resonance frequency of an LCR series circuit formed by the parasitic capacitance of a commercial power module was calculated by taking into account the wiring shape, and this frequency matched the measured value within 4.2%. These results validate our theoretical formulation and method.

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The topcoat thickness of thermal barrier coating (TBC) applied to a gas turbine blade was meaured using terahertz waves. The refractive index of the topcoat was obtained by frequency analysis of the waves reflected from the topcoat surface and the interface between the topcoat and bondcoat. The surface roughness of the topcoat surface was considered for improving the accuracy of the refractive index calculation. The topcoat thickness was obtained from the refractive index and the time separation between the reflected waves. The validity of the method was confirmed using a TBC sample with variable topcoat thickness, and the obtained topcoat thickness was in agreement with measurement results using a contact thickness gauge. Error analysis showed that the measurement error of the topcoat thickness was about 3%. The method was applied to a gas turbine blade with TBC, and the measured topcoat thickness agreed with microscope observation results of the cross section to within 6%, which was within the range of measurement error. The effect of curvature of the gas turbine blade surface did not result in significant measurement error. The results showed that terahertz waves are effective for nondestructive measurement of the topcoat thickness of TBC applied to gas turbine blades.

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The characteristics of photoluminescence of Cr³⁺ in the thermally grown oxide (TGO) layer in thermal barrier coating (TBC) for gas turbine blades was evaluated. A pulsed Nd:YAG laser of wavelength 532nm was used to excite Cr³⁺ in the TGO layer in TBC specimens, and the luminescence was detected at 694nm. Photoluminescence of Cr³⁺ was observed for TBC specimens heated for 100 hrs and 1000 hrs at 1100°C, but was not observed for the specimen without heating. The intensity of photoluminescence of Cr³⁺ for the heated specimens showed two radiative lifetimes, which are thought to be the radiative lifetimes of Cr³⁺ in different metal oxides, possibly Al₂O₃ and AlYO₃. Effects of self-absorption were not observed. In addition, the photoluminescence intensity was proportional to the excitation intensity, showing that the effects of saturation were absent.

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Autofluorescence of refrigerated squid mantle muscle was investigated. Fluorescence that was originated in reduced nicotinamide adenine dinucleotide (NADH) and tryptophan was observed in fresh squid mantle. A fluorescence peak wavelength of NADH from the squid mantle was shown 454nm and the fluorescence peak wavelength of tryptophan was shown 353nm. The fluorescence emission intensity of NADH decreased at time within 100 hours in the cold storage time. On the other hand, the fluorescence emission intensity of tryptophan hardly changed.

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In order to evaluate the visibility of road lighting, it is necessary to clarify the relationship between the visibility of the object and the luminous intensity distribution of the luminaire. In this paper, we consider the relationship between the visibility of the object and the luminous intensity distribution of the luminaire based on Revealing Power.

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Structures of electrostatic potential and ion outflow at magnetic reconnection were measured in spheromak merging experiment in TS-4 device. In counter-helicity spheromak merging, reconnection of opposing toroidal magnetic fields generates the radial gradient of electrostatic potential which causes asymmetry in the radial ion outflow pattern.

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To investigate the effect of pressboard aging states on its time domain dielectric characteristics, experiments are designed to measure the polarization and depolarization currents (PDC) of different aged pressboard samples. Firstly, new pressboard samples immersed in new transformer oil are thermally aged for different time intervals and then residual oil in aged pressboard samples is removed by de-oiling solvent. Secondly, these pressboard samples are dried in a vacuum oven to remove de-oiling solvent and moisture. The degree of polymerization (DP) is measured to characterize the aging states of each sample. Finally, PDC tests are performed on each pressboard sample respectively in vacuum and new-oil-impregnated ambiences. Experimental results show that badly aged pressboard exhibits larger polarization, depolarization and conduction currents. The deterioration of solid insulation increases its conductivity and enhances its polarization.

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