IEEJ Transactions on Fundamentals and Materials
Online ISSN : 1347-5533
Print ISSN : 0385-4205
ISSN-L : 0385-4205
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Volume 134, Issue 3
Displaying 1-14 of 14 articles from this issue
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Paper
  • Numerical Simulation of Surface Streamer Propagation in Atmospheric Air
    Daiki Tanaka, Akiko Kumada, Kunihiko Hidaka
    2014 Volume 134 Issue 3 Pages 118-125
    Published: March 01, 2014
    Released on J-STAGE: March 01, 2014
    DOIhttps://doi.org/10.1541/ieejfms.134.118
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    Numerical simulations of surface streamer propagation in atmospheric air are carried out, and calculation results well correspond with experimental results by Pockels sensor system. Propagation and decay processes of the surface streamer are clearly specified from the calculation result. Number densities of charged particle are 1020m-3 and 1018m-3 in positive and negative surface streamers, respectively. In the positive polarity, the cathode fall region forms between the surface streamer and the dielectric barrier, and reduced electric field reaches about 1000 Td at the streamer head and 10-20 Td at the streamer channel. In the negative polarity, the streamer contacts the dielectric barrier surface, and reduced electric field reaches about 150 Td at the streamer head and 50 Td at the streamer channel.
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  • Decomposition of Persistent Organic Compounds in Water using DC Corona Discharge on Surface of Water
    Tomoaki Miichi, Hiroki Noguchi, Yohei Uegaito, Yuya Fujimoto, Risa Nar ...
    2014 Volume 134 Issue 3 Pages 126-133
    Published: March 01, 2014
    Released on J-STAGE: March 01, 2014
    DOIhttps://doi.org/10.1541/ieejfms.134.126
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    A method for decomposing persistent organic compounds in water by DC corona on water was investigated. The acetic acid as a persistent material was decomposed by corona discharge in oxygen 4 mm away from the surface of the water. The acetic acid in 10 ml solution was a concentration of 9.6-207 mg/l. The number of electrodes where the corona was generated was 4 or 8, the voltage was between 6.2 kV and 9.2 kV, and the current was between 0.09 mA and 0.34 mA. As the voltage and the number of discharge electrodes increased, the decomposition rate increased. The maximum decomposition speed of 4.8 µg/min was obtained with 8 discharge electrodes in initial concentration 20 mg/l of acetic acid. More numbers of the electrode were effective for the decomposition of the acetic acid in the equal discharge power.
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  • Study on Effects of Transient Electromagnetic Fields on Growth of Broccoli
    Ryota Ito, Masao Masugi
    2014 Volume 134 Issue 3 Pages 134-141
    Published: March 01, 2014
    Released on J-STAGE: March 01, 2014
    DOIhttps://doi.org/10.1541/ieejfms.134.134
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    This paper describes an analysis of the effects of transient electromagnetic fields on the growth of a plant. In our experiment, a single transient electromagnetic field, which was radiated from a discharge electrode (2 cm) of a discharge generator, was periodically applied to seeds and seedlings of broccoli (Brassica oleracea var italica) for three weeks. The pulse application cycles were set to 1 day and 3 days with charging voltages of 10 kV and 15 kV. In a growth environment, temperature and humidity were set to 25 (±3) °C and 50 (±10) %, respectively. Light photon at the top of leaf was set to 110 (±30) µmol/m2s and illuminating lamp lighted for 24 hours. Then, we measured the length and chlorophyll density of leaves of the growing plants in each condition. Also, based on measured current that flowed through the discharge electrode, we evaluated the radiated electromagnetic energy level by using an electric dipole model. As a result, we found that samples, which had been applied 10kV/3days and 15kV/3days, became greater than the others by around 30%. Also, the chlorophyll density of 10kV/3days and 15kV/3days became higher than the others.
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  • Water Tree Retardation in MgO/LDPE Nanocomposite
    Muneaki Kurimoto, Tomoaki Tanaka, Yoshinobu Murakami, Tomohiko Katayam ...
    2014 Volume 134 Issue 3 Pages 142-147
    Published: March 01, 2014
    Released on J-STAGE: March 01, 2014
    DOIhttps://doi.org/10.1541/ieejfms.134.142
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    This paper presents water tree retardant characteristics of MgO/LDPE nanocomposite insulating material under the AC voltage application. Experimental results reveal that the addition of MgO nanoparticles retards the progress of water tree in LDPE matrix. Finally, we discuss the water tree retardant mechanism in the MgO/LDPE nanocomposite.
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  • Effect of Si Content on Iron Loss of Electrical Steel Sheet under Compressive Stress
    Yoshihiko Oda, Hiroaki Toda, Nobuo Shiga, Shoji Kasai, Tatsuhiko Hirat ...
    2014 Volume 134 Issue 3 Pages 148-153
    Published: March 01, 2014
    Released on J-STAGE: March 01, 2014
    DOIhttps://doi.org/10.1541/ieejfms.134.148
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    The magnetic properties of non-oriented electrical steel sheets under compressive stress were investigated. The iron loss under compressive stress decreases with the increase of Si content. In particular, a 6.5%Si steel sheet shows extremely low iron loss under compressive stress. This decrease is due to the decrease of magnetostriction. To evaluate the effect of magnetostriction on iron loss of the motor, we made IPM motors using 3%Si steel and 6.5%Si steel. In the motor using 3%Si steel, the motor loss is increased after the heat shrinking. On the contrary, in the motor using 6.5%Si steel, the motor loss showed little change after the heat shrinking.
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  • A.C. Breakdown Properties of Solidified Alcohol Aqueous-Solution
    Ryohei Tsuchiya, Yuji Muramoto, Noriyuki Shimizu
    2014 Volume 134 Issue 3 Pages 154-161
    Published: March 01, 2014
    Released on J-STAGE: March 01, 2014
    DOIhttps://doi.org/10.1541/ieejfms.134.154
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    We have been studied the use of ice, solidified H2O, as electrical insulating material at cryogenic temperature. Ice has excellent electrical breakdown strength. In addition, ice is environment-friendly material and easy to be molded into various shape because it is liquid at room temperature. However, ice has the several problems as electrical insulating material; one is that voids or cracks are easily formed.
    In this paper we tried to improve the A.C. breakdown strength of ice by mixture of water-soluble material, namely by producing solidified aqueous-solution. We chose alcohol as water-soluble material; namely ethanol, 1-propanol, 2-propanol, propylene glycol and glycerin. We examined the A.C. breakdown strength of solidified alcohol aqueous-solution at 77 K. As the results, the A.C. breakdown strength of solidified 2-propanol aqueous-solution shows the highest, 64% higher value than ice.
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Letter
  • Lightning-impulse Field Measurement by using Kerr Effect in Gas
    Tomoki Kamiya, Shigeyasu Matsuoka, Akiko Kumada, Kunihiko Hidaka
    2014 Volume 134 Issue 3 Pages 162-163
    Published: March 01, 2014
    Released on J-STAGE: March 01, 2014
    DOIhttps://doi.org/10.1541/ieejfms.134.162
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    The Kerr electro-optic sensing technique can provide us with one of ideal methods for measuring the electric field in medium without causing any field disturbance. As Kerr constants of gases are very small, the Kerr field measuring system generally adopts modulation technique to improve its sensitivity. The upper response frequency limit of the sensing system is regulated by the modulation frequency. In this article, the modulation frequency is raised up to 200MHz, and the lightning impulse field is successfully measured by using Kerr effect in gas.
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  • Sensitive Pockels Sensor by Multiple Reflection Method
    Tomoki Kamiya, Shigeyasu Matsuoka, Akiko Kumada, Kunihiko Hidaka, Kazu ...
    2014 Volume 134 Issue 3 Pages 164-165
    Published: March 01, 2014
    Released on J-STAGE: March 01, 2014
    DOIhttps://doi.org/10.1541/ieejfms.134.164
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    Highly sensitive potential difference sensor is developed with BGO Pockels sensor in longitudinal modulation geometry. By introducing multiple reflection method, the half wave voltage, which corresponds to the indicator of the sensitivity, is improved around 30 times, and the detectable potential difference with this sensor reaches less than 10V. The potential difference around 100V insulated wire is successfully measured with this sensor.
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