Ecotechnology, a new compound of ecology and technology, to develop sustainable human activities keeping good environment on the earth, is overlooked from the viewpoints of electrical materials and machines in power use. Life cycle assessment (LCA) indicates most of carbon dioxide gas during the lifetime of electric machines from resources to disposals comes from power consumption during the operation. Energy saving in four electric machines has been accelerated since the so-called top runner system started in 1997. New products and technologies on lower losses have been developed in electrical steel sheets while the amorphous transformers have had some market share of distribution transformers. This is a summery of the activities of the committee on magnetic materials in power use of which report will be published.

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V-t characteristics with a time span of 1-1000 μ sec were measured for vacuum gaps in order to identify the influence of electrode arrangement and gap length on V-t characteristics of vacuum gaps. Plate to plate, ring to plate and sphere to plate gaps with distances of 1-12mm were used for the measurements. As a result, the following points were observed.
(a) Plate to plate gaps:
  (1) When the gap length is less than approximately 1mm, breakdown voltage is independent of breakdown time.
  (2) When the gap length is more than approximately 1mm, the breakdown voltage decreases with increases in breakdown time.
  (3) AC breakdown voltage is 70-80% of 1.15/3.8msec switching impulse breakdown voltage. DC breakdown voltage is almost the same as the AC. The impulse ratio between 1.2/50 μ sec lightning impulse breakdown voltage and the AC is 1.25.
(b) Ring to plate and sphere to plate gaps:
  (4) Under positive voltage applications, behaviour of V-t characteristics in the plate to plate gaps of less than d=1mm was observed. This feature was identified under all the gap length.
  (5) Under negative voltage applications, behaviour of both points (1) and (2) above was observed. Critical gap length where the behaviour changed from point (1) to (2) depended on the radial curvature of high voltage electrodes.

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The yearly change of graduates from the schools of various level (technical high school, school for technicians, college and university) is analysed. The source is the statistics of Ministry of Education. Approximately 3.1 million electrical engineers and technicians were educated in Japan in the period from 1945 to 1999. The graduates from electrical engineering courses/schools were almost masculine. We can say that one out of 10-15 young boys became electrical engineers/technicians. In the period, big changes in the number of electrical graduates occurred three times. The first was the transition from old education system to new one just after WWII. The second occurred in the mid-1960s, accompanying the economic growth in Japan: the technical high schools were newly established. In the third, the number of electrical graduates has been decreasing gradually since the 1990s. In recent years, approximately seventy thousand electrical engineers and technicians are educated every year.

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In order to increase an energy conversion efficiency of “Solar TEC” which is a thermionic energy converter driven by the solar light, the emitter should absorb the solar light with high rate. In the present paper, the emitter with light trap is proposed and the effective absorptivity α_eff is numerically estimated. It is found that α_eff is remarkably increased from 0.3 to 0.92 by adjusting the angle of a cone which is equipped inside the light trap to improve α_eff, while an emissivity of the emitter ε remains original value. Moreover, the method to obtain α_eff and ε experimentally was introduced.

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In order to realize a high conversion efficiency of solar to electric power, a novel emitter with a high solar power absorption should be developed. According to our previous paper in which an effective solar power absorption co-efficiency α is numerically calculated, the equipment with the light trap is found most effective to improve α of the emitter. In the present work, several emitters with different structures have been heated by condensed solar light and α has been estimated by comparing experimental emitter temperature with numerically calculated one. As a result, it is verified that α is improved from 0.25 to 0.7 by the light trap. However, it is found that the effect of the light trap is suppressed when the emitter is smaller than the area focused by the lens.

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In the biomagnetic measurement performed in laboratory, the biomagnetic signal is extremely weak compared with environmental magnetic noise. We propose the noise reduction method of estimating the subspace spanned by the sensor outputs. It is estimated from the lead-field vectors for the uniformly distributed lattice points in the head. It has been shown by simulation that projection of the measurement to the signal subspace reduces the noise effectively. By applying this method to vector AEF data (averaging: 10, 20, 50), the effect of noise reduction with 30 % was obtained to each data. And, it has been shown this method is more effectively vector MEG than not vector MEG.

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Biomagnetic signals such as MEG (magnetoencephalography) and MCG (magnetocardiography) are very weak compared with those of environmental magnetic fields due to trains and motor cars. In Japan, the fluctuation and frequency dependence of the environmental magnetic noises at extremely low frequencies in urban areas are considerably different between the daytime when direct-current (DC) electric railcars are running and the nighttime when there is no traffic. In order to reduce those noises, magnetically shielded rooms (MSR) should be installed. The shielding effects (SE) of an MSR should be determined by the S/N ratio of the biomagnetic signals to the environmental magnetic noises. Therefore, it is important to understand and predict the characteristics and the amplitude of the fluctuation of the magnetic fields (AFM) at extremely low frequencies resulting from the DC electric railcars. In this paper, firstly, AFM’s within and outside of two kinds of MSR at an individual location are compared to each other in order to confirm that the AFM in a MSR depends not only on the environmental magnetic fields but also on the SE of the MSR. Secondly, the fluctuations of the magnetic fields were measured at three locations near railroads of DC electric railcars. The fluctuations of the magnetic noise at these three measurement points are mainly due to the DC electric railcars. The difference of the amplitude of the fluctuation of magnetic noise depends on the traffic density and the leakage resistance between the rail and the ground. Thirdly, the relationship between the AFM and the distance from the railroad was investigated. The decay factor can be obtained from the relationship between the AFM and the distance from the railroad. These decay factors also depend on the leakage resistance. The decay factors measured are in good agreement with these calculated. By comparing the AFM’s measured as a function of the distance from the railroad with those analyzed as a function of the leakage electric current to the ground, a method of predicting AFM’s due to the DC electric railcars was proposed.

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The condition of materials affected by irradiations is one of the concerns in the space technology. Under irradiation, polymeric materials are able to store charges resulting in electrostatic discharges with potential harmfull consequences. The aim of this work is to explore the possibility of the in situ measurement of space charge distributions in polymers exposed to electron beam irradiation. We have developed a small PEA system that can be mounted in the vacuum chamber in order to measure the internal space charge of materials during the irradiation. Negative charge accumulation was clearly observed during electron beam irradiation, and the position depended on the electron energy. These results proves that the new in-situ space charge observation system by using PEA method can monitor the space charge behaviour in vacuum.

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