Electric double-layer capacitors (EDLCs) have the advantages of much longer life and unnecessary maintenance. However, for EDLCs used for a long period, a decrease of electrostatic capacity and an increase in internal resistance are recognized. In this study, in order to clarify the factors responsible for the deterioration of EDLCs used for a long period, chemical analysis was conducted on each component such as an activated carbon electrode and an electrolytes solution. The obtained data were compared with those from a new EDLC. The results showed that long-term use reduced electrostatic capacity about 5% and made internal resistance increase by about 1.7 times. The quantity of oxygen due to surface functional groups of the activated carbon electrode was confirmed using electron spectroscopy for chemical analysis (ESCA). As compared with results obtained from a new EDLC, long-term use made the ratio of O-C=O deriving from carboxyl group (-COOH) to C-C increase 1.2 times. The ratio of C-O deriving from hydroxyl group (-OH) to C-C also increased 1.4 times. In addition, it was found that BET surface area decreased about 40% and that pores whose diameter was in the range between 0.8 to 20 nm disappeared.

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For the purpose of supporting the understanding of partial discharge (PD) phenomena for student education in electrical engineering, an introduction of experimental proposal for practical training which includes experiment and theoretical calculation is taken into consideration. In succession of the technical education for diagnosis of insulation degradation, the knowledge about PD carried out an important role in the background of this consideration. The experimental sample which is laminating an insulated board with a cylindrical shape cavity between the common glass-reinforced epoxy laminate boards, which mostly used in printed circuit boards, was made for the evaluation of the internal PD phenomenon. In addition, the medium-layer board with the cavity was evaluated also to the case where it was considered as a PTFE board and a CFRP board. The content of this experiment is intended to make it understand the intensity of internal PD generated by impression of AC high voltage. The amount q of charges (the apparent amount of PD charges) in the cavity was observed first, and the amount q_max of the maximum charges was evaluated below as compared with a simple calculation model.

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We deposited SiCN thin films by RF plasma CVD (Chemical Vapor Deposition) method using a mixture of Tetramethylsilane (TMS), nitrogen, and hydrogen gas. Deposited films were measured some properties with Fourier-Transform Infrared Spectroscopy (FT-IR), X-ray Photoelectron Spectroscopy (XPS), Ellipsometry and Atomic Force Microscope (AFM). We found that the temperature of substrate increased elimination and absorption reaction on the surface, and a fine film could be deposited at the temperature of 973K. To deposit SiCN with lower temperature, we changed H₂ flow rate. As results, we found that H₂ flow rate had great influence on the efficiency of decomposition of TMS. Moreover, the roughness of substrate was affected by the mixture rate of TMS. We could obtain the films nearly similar to the 973K ones at the state of 100Pa of pressure, 773K of substrate temperature, 80sccm of H₂ flow rate, and TMS mixture rate of 3% to 5%. In particular, 5% of TMS mixture rate could be considered as the best condition on this experiment.

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Sakai et al.^(1)(3)(8) demonstrated that a strong magnetic field at a lightning strike induces isothermal remanent magnetization in the materials around the point of lightning strike. In some cases, the ground or underground materials, or both are possibly heated by the lightning strike. They may thereby, acquire another type of magnetization, called thermal remanent magnetization. Fulgurite that is produced underground at the lightning is a typical result of the heating effect caused by the lightning electric current.  We investigated the remanent magnetization of fulgurite found at Iwamizawa, Hokkaido, Japan. The study verified that the fulgurite has thermal remanent magnetization which recorded the geomagnetic field. We estimate that the temperature of the fulgurite immediately after the lightning strike was over Curie temperature (580°C) of the included magnetite minerals. Experimental results indicate that when the fulgurite was formed, the lightning current already disappeared and did not affect the remanent magnetization. A magnetic study at the lightning-damaged area could investigate the heating effect of lightning current as well as its path and magnitude.

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This paper describes an analysis of trend changes of the total electron content (TEC) on the ionosphere as a possible precursor to massive earthquakes from 2005 to 2012 around Japan. To evaluate the TEC, we defined an index called Ratio, which can measure the deviation of a trend line of TEC around the target period. Regarding the earthquakes whose magnitude was more than 5, the results confirmed that the value of Ratio tended to be affected especially when the depth of earthquake occurrence points was less than 100 km.

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Developing the recording notebook for graduation research on 4th grade students in the Department of Electrical and Electronic Engineering (EE), Nagoya Institute of Technology, we introduce a student pocket notebook (SPN) for all students in EE. By encouraging to write down keywords on each class into SPN, students obtain study records which enable to enhance the learning motivation. In this letter, the composition of the SPN and its problem are introduced.

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