We investigated a treatment method for hyperthermia in which a ferromagnetic implant with a low curie temperature (FILCT) is implanted into a malignant tumor and then a high-frequency magnetic field is applied outside the body. In earlier studies, we confirmed that the target temperature of the tumor can be non-invasively monitored by detecting changes in the magnetic field caused by magnetic permeability changes. It was very difficult, however, to detect FILCT temperature if the applied magnetic field was in an unstable state. Additionally, if the initial bias is higher, it becomes more difficult to detect FILCT temperature because the resolution of the lock-in amplifier is reduced. To improve the accuracy of low-invasive temperature measurement, we formulated a method that reduces the drift in the pickup coil voltage caused by instability from the applied magnetic field. In addition, we experimentally confirmed that the influence from fluctuation in the applied magnetic field can be reduced by adjusting the initial bias value near 0 V.

View full abstract

In the early Meiji era, the western civilization was flowed into Japan, and the flow of civilization could be established. In the field of the electricity the electric telegraph and the electric light have spread nationwide. These were accomplished by a flow of academic cultivation planted in the Edo period. In the Kyoho five years (in 1720), in order to improve the promotion of the encouragement of new industry and medical technology, Shogun Yoshimune Tokugawa removed an embargo on importation of the Netherlands books unrelated to Christianity. Natural Science technology in Western Europe was coming in and the electrical engineering was starting. So in this paper we describe the electrical machinery technology in Japan in comparison with that of Western Europe at that time of the Edo period. Many people have contributed to the formation of electrical engineering in the Edo period. It is considered that three people, Gennai Hiraga, Soukichi Hashimoto, Koumin Kawamoto especially contributed to the formation of electrical engineering. It is because we think they had many knowledge and they had made a large contribution to electrical science and engineering during the Edo period.

View full abstract

In this paper, we propose two control methods of the static impulse voltage generator to lower the influence of DC voltage source fluctuations on the output voltage and to improve its efficiency by reusing discarded inductive storage energy. Introducing the output voltage control adjusting the charging period of capacitive and inductive energy in accordance with the source voltage, the output voltage fluctuation by the source voltage decreased 61.1%. Applying the reusing method to it, we estimated with the circuit simulation that the amount of energy which could be recovered was 21.0% and the efficiency of energy transfer was improved from 60.4% to 76.7%.

View full abstract

Pulsed experiment is simulated by Monte Carlo simulation for two kinds of constant collision frequency model gases, and longitudinal diffusion coefficient D_L', which is measured in “Pulse experiment”, is deduced. D_L' is compared with the diffusion coefficient D_L, obtained by the simulation of Time-of-Flight experiment. It is found that D_L' does not necessarily agree with D_L, and that the difference between D_L' and D_L tends to increase when the values of E/N and effective ionisation coefficient increase.

View full abstract

Ozone zero phenomena in an atmospheric pressure oxygen dielectric barrier discharge have been one of the major problems during a long time operation of ozone generator. However, adding a small amount of nitrogen makes recovery of ozone generation from the depression. To make clear the mechanism of recovery, zero dimensional model has been developed and simulated. As a result, with addition of nitrogen or nitrogen monoxide, the recovery process can be seen and ozone density increased. The reaction of nitrogen atoms with oxygen molecules makes oxygen atoms which is main precursor species of ozone. This generation of oxygen atoms are effective to increase ozone.

View full abstract

In this study, the insulating properties on DC voltage in hydrogen atmosphere at high temperatures (600-850°C) were evaluated for alumina (Al₂O₃), magnesia (MgO), silicon nitride (Si₃N₄) and mica (KMg₃(Si₃Al)O₁₀(OH)₂) to comprehend the difference in insulating properties of oxide, nitride and mineral. The activation energies of electrical conductivity of alumina and magnesia in hydrogen were larger than those in air. On the other hand, at silicon nitride and mica electrical conduction in hydrogen were same as those in air. Therefore low oxygen partial pressure would have some influence on electrical conduction of oxide. And increasing temperature didn't bring a huge change of electrical conduction mechanism in all materials and both of the atmospheres. The maximum amounts of partial discharge in hydrogen tended to increase compared to those in air at high voltage. Applied voltage, in which the maximum amounts of partial discharge started to increase rapidly, became lower with increasing temperature in all materials and both of the atmospheres. The total amounts of partial discharge tended to decrease with increasing temperature in all materials and both of the atmospheres. However, at exceeding certain temperatures, the total amounts of partial discharge increased or slightly decreased.

View full abstract

[in Japanese]

View full abstract