In the Wiener-Hopf analysis of wave scattering problems related to the modified Wiener-Hopf geometries, solutions often contain infinite branch-cut integrals with unknown integrands and/or infinite series with unknown coefficients. It is therefore required to evaluate these infinite integrals and series appropriately in order for the analysis to be complete. In this paper, we shall investigate the solutions arising in the boundary value problems for the modified Wiener-Hopf geometries, and develop efficient methods for obtaining approximate solutions based on a rigorous asymptotics. Applications of the results to specific scattering problems are discussed. Some numerical results on the radar cross section (RCS) are also presented.

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It had been widely accepted that a dipole located close to a reflector does not radiate radio wave due to the cancellation with the wave from its image dipole. We proved this prejudice false by studying its physics theoretically and experimentally. Eventually, we proposed a novel Ultra Low Profile Dipole (ULPD), which has a built-in balun and impedance matching capability to realize excellent antenna characteristics. This paper describes the history and way of thinking as for ULPD. A basic ULPD with two inputs shows to have a peculiar quadruple mode instead of two dipole modes, and the antenna gain is 8.4 dBi or more. Then, a practical ULPD with a single input is proposed, and is shown to have almost the same characteristics as the basic ULPD.

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The coupling characteristics of the optical fiber with a circular hollow pit is important in order to design a fiber device. The optical fiber with a circular hollow pit can separate x-polarization and y-polarization. The polarization splitter constructed from the optical fiber with a circular hollow pit can take out x-polarization and y-polarization separately due to the difference of coupling strengths of polarization. We propose a new polarization splitter. One-half of new polarization splitter is used for a depressed clad fiber and the half of new polarization splitter is used for the fiber with a circular hollow pit outside a core. When the width t/a₁ of the depressed clad fiber is varied in the range 0.5≦t/a₁≦3.0, the device length L and the bandwidth BW_-15 at R≦-15dB (R: the extinction ratio) are investigated. It is found at t/a₁=3.0 and Δ₅=-0.322% that: (1) L takes its minimum value 3.24mm ; (2) BW_-15 takes its maximum value 74.9nm.

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A numerical technique for the analysis of the EM field by moving materials can be significantly important for the realization of new RF-MEMS and nano-optical components such as tunable capacitors and switching devices. In this paper, the Overset Grid Generation method combined with the FDTD method considering Lorentz transformation is applied to analyze the EM wave scattering from a uniformly moving dielectric and conducting body. The ratios of the amplitude for the transmitted and the reflected wave to the incident wave are investigated. The effect of the numerical parameters on accuracy and stability is studied. The comparisons of the numerical and theoretical results show good agreements between both results.

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Patients with hyperthermia have been increasing in recent years with the progress of global warming. Children and elderly tend to become hyperthermia for passive heat exposure and/or solar radiation. The reason for this tendency is considered as the morphological and functional differences between younger adults and children/older adults. In particular, children have morphological feature not only their height and weight are low but also they have a greater body surface area-to-mass ratio than that of the adults. The elderly has lower sweating rate as compared with the younger adults, while its mechanism is still controversial. In the present study, with numeric Japanese male and 3-year-old models, we analyzed core temperature elevation and perspiration in the adult and child phantoms for simultaneous solar and ambient heat exposure. At first, the threshold for activating the sweating in the older individuals was found to be about 1.5°C higher than that in the younger individuals by comparing the computational results with measured data. In addition, we found that core temperature elevation in the child model for solar and heat exposure was greater than that in the adult model, which is primary attributable to body surface area-to-mass ratio. Thus, the mechanism of hyperthermia in the elderly and child is different, although they are both sensitive to heat exposure as compared to younger adults.

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It has been said that the fields of science and engineering may lose attractiveness for university applicants in Japan, resulting in shortage of graduates. The survey conducted by the author from the fiscal year 2005 suggested the importance of the lecture which may include the knowledge of high-school students and advanced technology. Thus, it is essential to develop the lecture content suitable to the high-school students. We computed and visualized the induced current in the human body due to lightning current and electrostatic discharge. This paper presents the computational procedure for calculating the induced current with emphasis of explanation based on the science for high-school students. Then, the content of recent popularization enlightenment activity is presented. The post facto assessment showed that the satisfactory was improved to 87% from 73% by introducing the content developed here.

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As a part of the nuclear fuel cycle in Japan, the mixed oxide (MOX) fuels are produced through the microwave heating of the Pu/U mixed nitrate solution obtained from spent fuels. In this work, we investigate the effect of a spacer between the bottom of cavity and solution dish in microwave oven cavity to heat uniformly Pu/U mixed nitrate solution for producing MOX fuels. As a result, we show the effectiveness of inserting the spacer for a uniform heating of the solution by evaluating the top-to-bottom ratio.

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In this paper, we present the results from two sets of independently performed experiments—real and simulated— which adopt the contact failure model. This model provides an explanation of contact failures caused by faulty transmission line connectors for the purpose of investigating the common-mode (CM) current, which is one of the factors that cause noise radiation. In the first experiment, CM current is measured while gradually increasing contact resistance. In the second experiment, the effect on CM current as the number of contact points is gradually decreased is examined. Both experiments are performed within the uplink bandwidth of cable television (CATV) internet transmission. From both sets of experimental results, we conclude that, in order to maintain electromagnetic compatibility of transmission lines in CATV, it is important for the contact boundary of a connector to have low contact resistance, a sufficient number of contact points, and a symmetric contact distribution.

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Atmospheric-pressure, non-thermal, plasma jet produced by using helium gas has been studied for various applications. Especially, plasma applications for biological treatment are attracted and researched all over the world. In this paper, various kinds of cell culture mediums were irradiated plasma jet, and its components were analyzed. The results showed that irradiating plasma jet to cell culture medium could cause to change its pH, electric conductivity and so on. These results suggest that irradiating plasma jet might cause to change cell form and to kill them. Moreover, plasma jet generate UV light, it can be cause to kill cells. It found that irradiation time of plasma jet is very important factor to treat cells.

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The capillary discharge technique has been applied to produce thin film of Diamond-Like Carbon (DLC). In this technique, the deposition is based on an ablation process. In this technique, pulsed electron and plasma beams irradiate the target through the discharge tube and make plume on the target. Ablated particles from the target are deposited as the thin films on the substrate. Until now, this technique has not yet been applied to produce the DLC film. We have tried to apply this technique to grow the DLC films with higher hardness and quality. Graphite disk was used as a target material. We have found that the ablation energy can be controlled by the pinching electron beam in the discharge tube. The C2-Swan-Band of the C2 (dimmer of C), which is believed to the evidence of nucleus formation of nano-particles, was found in the optical emission spectrum of the plume. And the higher energy C⁺, and C²⁺ ions, which are species for sp3 bond of diamond formation, were found in the optical emission spectrum of the plume too. Deposition rate of the DLC film showed a linear relationship with the discharge voltage. Hardness of deposited DLC films was measured to be 20-80 GPa. The surface roughness (Ra) of the deposited DLC films was about 0.02 μm. We conclude from the above results that the capillary discharge technique can be one of the superior technique for producing DLC films with high hardness and smooth surface.

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We have been studying the Pulsed Plasma Deposition (PPD) technique for applying diamond-like carbon film deposition. This technique is one of the applications of the capillary discharge, and the deposition process is based on an ablation. In this study, we have found that the discharge tube material affect the discharge condition and the optical emission spectrum of the plume. We have also succeeded to increase the discharge current using a earth attached to the capillary tube. This earth has been effective for stabilizing the discharge. It can be concluded that the electrical properties (dielectric constant and conductivity) and physical property (melting point) of the discharge tube affect the capillary discharge.

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A inspection regarding surface rolled sintered gears performed in-line is required. The authors have proposed a inspection method using an eddy-current sensor. Since this method uses the eddy-current, a inspection of gears is possible in a nondestructive manner with a short time. In this paper, in order to perform a inspection using an eddy-current sensor, porosity, residual stress, resistivity, and relative permeability of the surface rolled sintered steel are measured. Furthermore, output voltage characteristics of surface rolled sintered gears that the amounts of surface rolling differ are measured. As a result, it is clarified that porosity and resistivity decrease and relative permeability increase with increasing residual stress. Moreover, it is clarified that over surface rolled gear can be judged with output voltage.

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Because a huge number of ground coils are used outdoors for an extended period of time in the superconducting magnetically levitated transportation (Maglev) system, high reliability of ground coils and the cost reduction are required. The propulsion coil especially needs the high insulation stability as high-voltage equipment. Because the ground coil, which is made with the resin-molded winding, does not have a core in the structure, the ground coil must be exposed to the electromagnetic force directly. Therefore, there is a possibility that minute defects in the molded resin of the ground coil may expand, become apparent, and lead to the deterioration of insulation stability. In this paper, we examined the insulation diagnosis to assess the existence/nonexistence of the inside defect and locate the defect by setting a simulated void-defect inside the molded resin of the ground coil and detecting the electromagnetic waves effectively that are emitted from a partial discharge at the defect point.

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A lot of hetero charge was accumulated in Polyimide (PI) film containing water under high electrical stress. The positive charge was observed near cathode and the negative charge was near anode. The dynamic behavior of hetero charge complicated characteristics in space and time. A small amount of hetero charge was observed at an initial period, however the accumulated hetero charge disappeared soon. A few minutes later, a lot of hetero charge was observed again and a breakdown occurred finally. In order to analyze the complicated hetero charge behavior, the energy band structure of Polyimide (3 molecular size) which was subjected to water (some H₂O) was obtained by using the Quantum Chemical Calculation. The hole-electron pair generation probability and the hole and electron hopping probability were evaluated from the values of energy gap and effective trap level respectively, which were obtained from the Quantum Chemical Calculation. It was found that water uptake narrowed the energy gap in PI, and the generation probability of hole-electron pair was increased with decreasing energy gap. In addition, the hopping probability of hole carrier also increased with decreasing the energy gap.

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Bow-tie trees (BTTs) generated by microscopic contaminants or voids in insulators of XLPE cables still remain a factor contributing to the deterioration. It has been reported that redox reactions of ions diffusing in XLPE lead to molecular chain cleavage. In such an electrochemical mechanism, the participation of oxygen other than ions is suspected. In order to examine the influence of oxygen on BTT generation and progress, we performed various experiments controlling oxygen gas by vacuum degassing, a gas barrier film, etc. The number of BTTs and the maximum BTT length of XLPE samples aged at 60°C increased with the water content. However, several of the data deviated significantly from these relationships. These results represent that BTT generation and progress were enhanced by vacuum degassing and inhibited by wrapping the samples with a gas barrier film or bubbling air through the tap water to immerse the samples. On the whole, the behavior of BTT generation toward supplying or shielding of oxygen was not consistent. The experimental results can be qualitatively explained by diffusion or permeation of ions and water rather than oxygen gas, thus oxygen seems not to be directly associated with BTT generation and progress.

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In this letter, effect of temperature gradient of thermally stimulated depolarization current (TSDC) is investigated, by using electrode systems with different structure, which are asymmetric and symmetric electrodes, TSDC and temperature difference measurement results show that, the temperature gradient caused by uneven heating condition of asymmetric electrode system will affect the reliability and accuracy of TSDC measurement. That is: under the symmetric electrodes system, a complete TSDC curve consists of two distinct peaks named α peak and ρ peak, while under the asymmetric electrode system, ρ peak can not be observed.

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Repetitive merging of spherical tokamak (ST) plasma was demonstrated in the TS-4 device using oscillating poloidal field (PF) coil currents. The oscillating induction current is transformed into plasma currents of small ST plasmas, if its polarity satisfies the Shafranov condition. This natural rectification was found to form repetitively small ST plasmas with single helicity, and their merging gradually drives the plasma current of the main ST plasmas.

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