IEEJ Transactions on Fundamentals and Materials
Online ISSN : 1347-5533
Print ISSN : 0385-4205
ISSN-L : 0385-4205
Volume 140, Issue 5
Displaying 1-10 of 10 articles from this issue
Paper
  • Ryo Nishimura
    2020 Volume 140 Issue 5 Pages 263-268
    Published: May 01, 2020
    Released on J-STAGE: May 01, 2020
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    Japanese intellects of Late Edo period (1720~1867) heard of that thunder and the essence of phenomena occurring when operating friction generators are same. Some of them called “essence of electricity” chi (essence) and tried to explain the electric phenomena by using Yin-Yang theory (In Chinese philosophy, Yin and Yang are opposite forces, such as hard and soft, that continuously changes and forms a basis of everything. It is believed that everything contains both Yin and Yang in a balance). It is described in this paper that how electricity and its phenomena are interpreted in that times (1720~1888) from the information in books written in that times.

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  • Yoshifumi Maeda, Toru Iwao
    2020 Volume 140 Issue 5 Pages 269-275
    Published: May 01, 2020
    Released on J-STAGE: May 01, 2020
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    Gas metal arc welding is used widely because this is the high efficient and quality joining technology. However, the welding defect occurs because of the arc deflection caused by the strong wind. The preventive technology of arc deflection is important. It is possible that the arc deflection is prevented using Lorentz force caused by the transverse magnetic field against lateral gas. The arc deflection has not been elucidated because the measurement of three-dimensionally asymmetric temperature and the axial flow velocity distribution of arc is difficult at the only experiment. The 3-D numerical analysis is necessary to elucidate flow velocity affected by Lorentz force. In this study, the flow velocity distribution in the arc affected by the transverse magnetic field with the lateral gas flow for the elucidation of arc deflection was analyzed. The arc deflection was calculated with lateral gas flow and changing the transverse magnetic flux density using the electromagnetic thermal fluid (EMTF) simulation. As a result, the difference in arc deflection distance from the experiment was 0.4mm with a transverse magnetic flux density, indicating a similar tendency. In addition, the axial flow velocity increased and the radial flow velocity decreased with the electromagnetic force in the opposite direction against crosswind. Along with this, the arc deflection distance decreased.

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  • Maimi Mima, Tokihiro Narita, Hiroaki Miyake, Yasuhiro Tanaka, Masahiro ...
    2020 Volume 140 Issue 5 Pages 276-284
    Published: May 01, 2020
    Released on J-STAGE: May 01, 2020
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    Space charge accumulation characteristics in PAI (polyamide-imide), which are used as an insulating layer of motor windings, were observed under applying a rectangular voltage. Furthermore, PDIV (partial discharge inception voltage) in twisted pair wires coated with PAI was also measured by applying the rectangular voltage previously applied with a dc voltage (prestress), which generates the space charge. Since a change of PDIV was observed in the prestressed sample, it was concluded that the space charge accumulation may affect the change of PDIV.

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  • Kazuhiro Nishimura
    2020 Volume 140 Issue 5 Pages 285-291
    Published: May 01, 2020
    Released on J-STAGE: May 01, 2020
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    The strong magnetic field arrays by using cubic permanent magnets are proposed as a magnetic field source. The magnets are used two types of the magnetized directions: 6 and 18 directions. The array is three-dimensional structure: cube consisting of three, five, seven, and nine cubic magnets on the side. There are two types of the structures: through-hole and dead end in the center. For each cube magnet, the magnetic flux density of the center was calculated by the derived formulae which are solved the area integral by the integral formulae. It is a feature that the calculations are fast. The directions in which the magnetic flux density of the z-axis is maximized were selected, and the sum of their magnetic flux density was obtained. At the same time, each sum of the magnetic flux density of the x-axis and y-axis was selected to be zero. It found that the obtained results are independent of the length of one side. Therefore, the structures can also be combined to cover the structures. Although the operating point of the magnet is not taken into account, it was able to find the arrangements of more than 2 T. It was confirmed that the array of 24 cubes was consistent with the experiment.

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  • Takenori Nitta, Takayuki Usui, Hiroaki Iino, Akira Ohno, Jun-ichi Hann ...
    2020 Volume 140 Issue 5 Pages 292-298
    Published: May 01, 2020
    Released on J-STAGE: May 01, 2020
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    We have identified liquid crystalline phase emerged in an alkoxyalkl derivative of phenylbenzothienobenzothiphene (Ph-BTBT), i.e., 2-(propoxybutyl)-7-phenylbenzothienobenzithiophene Ph-BTBT-4O-3, and studied its charge carrier transport properties by Time-of-Flight experiments. Ph-BTBT-4O-3 exhibited smectic E phase (SmE) at a wide temperature range of -130 to 200 °C over 300 K, and its hole mobility was determined as a function of temperature and electric field. At the low temperature range lower than room temperatures, hole mobility exhibited Poole-Frenkel like dependence and carrier transport properties characterized by 81 meV for a Gaussian width of the density of states. On the other hand, hole mobility did not depend on electric field at the range beyond the room temperatures up to 200 °C and exhibited Arrhenius type of activation energy of 0.11 eV, from which we estimated reorganization energy of 0.44 eV. We discuss the present results in comparison with the previous results from 2-(thiopropoxybutyl)-7-phenylbenzothienobenzithiophene (Ph-BTBT-4S-3).

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Technical Note
  • Sultan Alkhteeb, Shigeru Oho, Hiroyuki Shimizu, Seisuke Nishimura
    2020 Volume 140 Issue 5 Pages 299-303
    Published: May 01, 2020
    Released on J-STAGE: May 01, 2020
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    The electrical features of carbon fiber reinforced plastic (CFRP) were studied with experiments involving an Arago's disk, a backside electrode, a capacitor, and a box made of CFRP plates and bars. The Arago's disk rotation showed anisotropic characteristics due to the orientation of the carbon fiber in CFRP, while the surface discharging with a CFRP backside electrode was independent of the CFRP material. The through-plate resistance and capacitance of a CFRP plate were obtained from its frequency response, and imperfect insulation at CFRP surfaces did not obstruct the measurement. The electromagnetic field in the CFRP box generated by artificial lightning included high-frequency ringing related to the size of the box.

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Letter
  • Mikio Mori, Saki Fukuda
    2020 Volume 140 Issue 5 Pages 304-305
    Published: May 01, 2020
    Released on J-STAGE: May 01, 2020
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    The principle of sound production in human whistling is not well-known. A good understanding of the principle would be very beneficial to both the trainer and the trainee. We previously built a physical model of a human vocal tract on whistling developed from a CT image of the vocal tract during whistling, and demonstrate that the whistle pitch increased by narrowing the oral cavity. However, some whistle performers change the whistle pitch without almost changing the oral cavity shape. No studies have investigated how the larynx affects the whistling. For this reason, we assumed that the whistling method that does not change the oral cavity may be caused by the influence of the laryngeal change on the resonance frequency. This letter studies how changes in the larynx affect whistling. As a result, we found that the whistle pitch can change without changing the oral cavity shape when the larynx was enlarged.

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