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Volume 125, Issue 5
Displaying 1-15 of 15 articles from this issue
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Review
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Kazuo Tanabe2005 Volume 125 Issue 5 Pages 397-401
Published: 2005
Released on J-STAGE: August 01, 2005
JOURNAL FREE ACCESSIt is needed to study the transient performance of electrical apparatus for lightning surges to ensure the electromagnetic compatibility (EMC) and to establish accident prevention. The electromagnetic transient program (EMTP) based on circuit theory has been applied to resolve the transient performance of electrical apparatus consisting of cables and conductors which are parallel to the ground surface, in which the propagation of TEM waves that are plane waves is implicated, and devices such as surge arresters represented by lumped elements. However, for example, vertical conductors, which are familiar in electrical apparatus, have not been modeled because TM waves propagate on such conductors. Furthermore, transient performance of almost all types of grounding electrode buried in the lossy ground, except buried wires parallel to the ground surface, is not clear. Then, full-wave computational analysis based on the finite difference time domain (FD-TD) method, which is familiar as numerical electromagnetic analysis method, have been used to calculate transient performance recently. The present article discusses the full-wave computational analysis method.View full abstractDownload PDF (4196K)
Paper
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Taiji Shoyama, Yoshio Yoshioka2005 Volume 125 Issue 5 Pages 402-408
Published: 2005
Released on J-STAGE: August 01, 2005
JOURNAL FREE ACCESSThe chemical reactions by silent discharge were investigated using a model, which considers micro discharge structure and diffusion of species from discharge channel. This paper describes the influence of H2O on the reaction paths and NO removal performances, under an assumption that H2O does not change the discharge parameter. The principal result is that NO removal efficiency declines as H2O increases. The reason of efficiency decline was analyzed by investigating reaction paths, and it was found that the suppression of O3 formation due to the consumption of O radicals by OH and HO2, and also NO formation by OH radicals are the reason of efficiency decline.View full abstractDownload PDF (6831K) -
Hiroyuki Toyota, Shigeyasu Matsuoka, Kunihiko Hidaka2005 Volume 125 Issue 5 Pages 409-414
Published: 2005
Released on J-STAGE: August 01, 2005
JOURNAL FREE ACCESSA square pulse voltage is useful for studying electrical discharge physics or very fast transient overvoltage issues. This paper describes sparkover voltages and time lag (V-t) characteristics of CF3I gas, which has very low environmental effects and high dielectric strength, and its mixtures with nitrogen gas or air in a very short time range below a microsecond. They are measured by using a steep-front square voltage with a rise time of 16 nanoseconds and a peak value of 200 kilovolts. Pure CF3I gas has 20 % higher dielectric strength than SF6 gas. V-t characteristics of CF3I-N2 or CF3I-air gas mixtures, which contain 60% CF3I gas, are equivalent to those of pure SF6 gas at the same total pressure. A quantitative evaluation of V-t characteristics by the equal area criterion is also performed. The equal area parameter which is obtained by applying a voltage enough high to make the formative time lag dominant should be chosen.View full abstractDownload PDF (935K) -
Hideaki Isogai2005 Volume 125 Issue 5 Pages 415-418
Published: 2005
Released on J-STAGE: August 01, 2005
JOURNAL FREE ACCESSMimetic method which measures the surface tension in the droplet rotation as to simulate zero gravity. By generating centrifugal force with that gravity-free state floats the liquid which intends to measure surface tension and that it gives rotating velocity as a spherical sample of the droplet state in this for the surface tension, it swells to the shape of the new spheroid, it balances. For universal go-back with enormous costs and instantaneous measurement by the falling facilities, it aimed at the establishment of the technique of which the practical high precision is obtained here, it can repeatedly carry out in the hand, since it does not break in the conclusion, in simplifying. That turned on certain vertical axis and the effect of the gravity which was the body force was reduced to the utmost by the contrivance of the mechanism with the advantage which obtains the clear extension image, and this method is more realizable as if the zero gravity was made.View full abstractDownload PDF (3662K) -
Solving Regularized Least Squares with Qualitatively Controlled Adaptive Cross-Approximated MatricesShoji Hamada, Akiyoshi Tatematsu2005 Volume 125 Issue 5 Pages 419-426
Published: 2005
Released on J-STAGE: August 01, 2005
JOURNAL FREE ACCESSThe adaptive cross-approximation (ACA) technique is applied to accelerating an inverse-problem solver that estimates charge distribution on a dielectric spacer. The ACA generates an approximated system-matrix that enables us to carry out high-speed inverse calculation. We designed an approximation procedure based on ACA with some additional concepts, that is, (a) partitioning of matrix based on algebraic information, (b) approximation quality control based on matrix-norms, and so on. The tested solver (LSQR for regularized least squares) with ACA demonstrates about 10 times faster performance than that by without ACA.View full abstractDownload PDF (608K) -
Yukihisa Suzuki, Masao Taki2005 Volume 125 Issue 5 Pages 427-433
Published: 2005
Released on J-STAGE: August 01, 2005
JOURNAL FREE ACCESSMagnetic fields around induction heating hobs are measured and evaluated with regard to the compliance with safety guidelines of human exposure. The magnetic flux density distributions are highly inhomogeneous and the maximum can exceed the reference levels of the guideline at the very proximity to the device. The induced current densities in human body exposed to these magnetic fields are estimated by numerical calculations by means of impedance method with an anatomical human model. The results indicate that induced currents are sufficiently lower than the basic restriction of the ICNIRP guideline. It is shown that the spatially peak incident field does not provide a relevant reference to compare with the reference level of guideline because it is too conservative but spatially averaged incident magnetic field provides much more relevant reference.View full abstractDownload PDF (2837K) -
Hidefumi Taniuchi, Mayu Yanagihara, Hideki Motomura, Masafumi Jinno, M ...2005 Volume 125 Issue 5 Pages 434-440
Published: 2005
Released on J-STAGE: August 01, 2005
JOURNAL FREE ACCESSIn these days, there are strong needs to reduce harmful mercury used for light sources. We have been developing mercury-free fluorescent lamps using xenon. In this study, we have investigated characteristics of the xenon fluorescent lamps which have an internal and an external electrodes by changing the shape of the electrodes and how to set them. It is shown that luminance is improved by enhancing ionization by thin inner electrode, or increasing the capacitance between electrodes by increasing the pitch of wound external electrode.View full abstractDownload PDF (950K) -
Iwami Nakamura, Shinnosuke Ishii, Hirosi Yamada2005 Volume 125 Issue 5 Pages 441-446
Published: 2005
Released on J-STAGE: August 01, 2005
JOURNAL FREE ACCESSWe simulated on the phenomena of transit conduction in the insulating liquid with added ionic molecules such as surfactant, by using the charge-injection model with dissociation-recombination. When the parameters of Ci (density of injected charge) and Co(density of created charge in the liquid) are Ci>Co in this simulation, the wave form of current density showed an injection-type with a peak, and when Ci<Co, it showed a dissociation-recombination-type. A decreasing characteristic appeared in the low electric field, maximum one in the middle field, and saturating one in the high field.View full abstractDownload PDF (5237K) -
Tadashi Murakami, Kenjirou Toryu, Hideki Motomura, Masafumi Jinno, Mas ...2005 Volume 125 Issue 5 Pages 447-453
Published: 2005
Released on J-STAGE: August 01, 2005
JOURNAL FREE ACCESSThe fluorescent lamps are widely used for general lighting in Japan because of their high efficacy, long life, high general color rendering index and so forth. Mercury which is used in fluoresent lamps for general lighting has a possibility to cause environmental problems. So we have been developing fluorecent lamps which contain only rare gases in place of mercury. The rare gas lamps are environmentally-friendly, but it has lower luminous flux than the mercury lamp has. Therefore, we have tried improving luminous flux of the rare gas lamp by expanding positive column. By setting an external electrode on the outside wall of lamp which has multi-pairs of electrodes, positive column expands and luminous flux increases. Luminous flux changes by setting position and width of an external electrode. Then luminous efficiency achieves 5lm/W. We obtain relatively larger luminous flux when setting an external electrode near the cathode comparing with the lamp without external electrode. Luminous flux also changes by changing a way of setting an external electrode. We have achieved largest luminous flux when spiral external electrode is wound on the lamp.View full abstractDownload PDF (648K) -
Treatment on Low NOx Concentration and DEP Collection with Barrier Discharge System Superposing TiO2Yasuhiro Takagi, Katsuhiko Hosoi, Yoshiyasu Ehara, Takeo Takahashi, Ta ...2005 Volume 125 Issue 5 Pages 454-460
Published: 2005
Released on J-STAGE: August 01, 2005
JOURNAL FREE ACCESSThe automobiles exhaust carbon particles and NOx into the air, and then gases accumulate in expressway tunnels. DC corona discharge is used widely in electrostatic precipitator (ESP). However, the ESP with DC corona discharge can little remove NOx. Therefore, we proposed a new barrier discharge type precharger to replace corona discharge type prechargers to remove NOx. When discharge is generated in the air, NOx necessarily is generated. Then, we need to grasp the lower limit NOx concentration to remove NOx from the gas. We focus attention on photocatalyst because it is effective in NOx removal. However, photocatalyst needs ultraviolet ray. Therefore, TiO2 is painted on barrier discharge electrodes, an ultraviolet ray included in discharge luminescence was irradiated to TiO2. Furthermore, the relationship between initial NOx concentration and removal characteristic is investigated in detail.View full abstractDownload PDF (5545K) -
Ayumu Sato, Yasunari Harada, Seishi Sekine, Masashi Ohkawa2005 Volume 125 Issue 5 Pages 461-465
Published: 2005
Released on J-STAGE: August 01, 2005
JOURNAL FREE ACCESSA scattering ellipsometry is a newly developed method to measure a complex refractive index of metal clusters at a high temperature region. The complex refractive index is required to determine a luminous efficacy, which is one of the most important factors to develop lamps, of cluster lamps. In this study, we built a scattering ellipsometer, and considered its accuracy of measurement through evaluations of the complex refractive index of gold particles at room temperature. In measurement, a Nd:YAG laser of 532 nm was used as the light source. The measured complex refractive index of gold particles was 0.31 in real part and 1.75 in imaginary part. A repeatable accuracy was evaluated 0.01 in real part and 0.02 in imaginary part from a standard deviation in measuring the complex refractive index 10 times in the same condition. Also, the size parameter of gold particles was 1.71, and its repeatable accuracy was 0.02. Such accuracy is sufficient to estimate characteristics of the cluster lamps, such as the spectral radiant flux, the luminous efficacy and so on.View full abstractDownload PDF (5712K) -
Koichiro Fujita, Hideki Matsuoka, Tatsuhiko Hiratani, Kenji Tahara, Ya ...2005 Volume 125 Issue 5 Pages 466-470
Published: 2005
Released on J-STAGE: August 01, 2005
JOURNAL FREE ACCESSRecently, cathode ray tubes (CRTs) have become flat and larger, and the magnetic shielding against the terrestrial magnetic field is becoming more important for CRTs to improve the image quality. As CRTs of TV sets and computer monitors are used after the degaussing process, it is necessary to consider the magnetic shielding effect in terms of the anhysteretic permeability. In this paper, dependence of anhysteretic permeability on the chemical composition and the microstructure of steel sheets for inner magnetic shields has been studied. In addition, the importance of anhysteretic permeability on magnetic shielding has been experimentally investigated.View full abstractDownload PDF (4708K) -
Daiichi Irisawa, Kumiko Imai, Koichi Shintomi, Akihito Yahara, Mitsuru ...2005 Volume 125 Issue 5 Pages 471-476
Published: 2005
Released on J-STAGE: August 01, 2005
JOURNAL FREE ACCESSSuperconducting shield which has wall thickness over London penetration depth can realize zero field environment in principle. But in policrystal superconductor, to contact with Josephson junction between crystals, critical current density is smaller, equivalent penatration depth is longer. Consequently it is possible that external magnetic field penetrate through a superconductive wall and deteriorate shielding property. We applied equivalent penetration depth to magnetic field determination method of superconductor and performed measurement of leakage field in BiSrCaCuO(2212 phase) superconducting hollow cylinders. As the result of that, leakage field was observed and the shielding effect is similar to analysis. In spite of that, we show that superconductor has good shielding property superior to ferromagnetic and can improve the limited shielding property by coupling to ferromagnetic.View full abstractDownload PDF (271K) -
Takashi Eiki, Takashi Honda, Jiro Yamasaki2005 Volume 125 Issue 5 Pages 477-481
Published: 2005
Released on J-STAGE: August 01, 2005
JOURNAL FREE ACCESSA dolphin-type swimming micro-robot has been developed for science education. This micro-robot, approximately 60mm in length, consists of a rigid body balanced with a float, and a propulsive mechanism including a magnet and an elastic fin. The mechanism features unique design based on biomimetics and a simple structure for easy construction. When external alternating magnetic fields are applied, the magnet oscillates angularly due to magnetic torque and then the caudal fin can produce a thrust. The micro-robot can swim at over 30cm/sec under alternating magnetic fields of 4kA/m at 20Hz. Results of a handicraft class at an elementary school have demonstrated that the micro-robot developed in this study is useful for science education.View full abstractDownload PDF (248K)
Letter
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Toshihiko Terado, Osamu Fujiwara2005 Volume 125 Issue 5 Pages 482-483
Published: 2005
Released on J-STAGE: August 01, 2005
JOURNAL FREE ACCESSIn this paper, a new method was proposed for 24-hour non-invasive and non-constraint monitoring of human's motion in bed. In the method several infrared markers were attached to the human body, and their three-dimensional coordinates was determined by using two-dimensional positioning detectors via a perspective view transformation. An application of the method to the motion track measurement for both of turning and breathing of a subject in bed demonstrated its feasibility.View full abstractDownload PDF (146K)
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