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Volume 129, Issue 8
Displaying 1-12 of 12 articles from this issue
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Review
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Hiroshi Koyama, Yoshikazu Hoshina2009 Volume 129 Issue 8 Pages 495-499
Published: August 01, 2009
Released on J-STAGE: August 01, 2009
JOURNAL FREE ACCESSHigh-voltage measurement is evaluated using a measurement system built combining a voltage divider, a measuring instrument, etc. A measurement system is calibrated as compared with a reference measurement system, and is maintaining accuracy. The IEC standard about high-voltage measurement is going to be revised, and especially the evaluation method of impulse voltage is changed greatly.View full abstractDownload PDF (484K)
Special Issue on Measurement Technology for Safety
Special Issue Paper
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Taiyo Matsumura, Takashi Ono2009 Volume 129 Issue 8 Pages 500-506
Published: August 01, 2009
Released on J-STAGE: August 01, 2009
JOURNAL FREE ACCESSIn this paper, warning time optimum control for level crossing with a continuous type train location detector using crossed inductive wires is proposed and its effect to shorten crossing warning times is discussed. As a result, we have demonstrated that the proposed method is effective in delaying the timing of the initiation of warning in line with the state of train operations in a simulation. It is also found that it is a feasible method when studying the characteristics of signal reception levels with a prototype onboard antenna fabricated in this study. We have also confirmed that we could shorten crossing warning time by about 40 [s] from results obtained in a simulated operation experiment. From the above, it is demonstrated that the proposed method is effective in shortening crossing warning time, one of the possible measures to mitigate the lengthening of crossing warning times. Through the adoption of this method, traffic interruption caused by a closed level crossing will be lessened, reducing people's irritation while waiting for the long-closed gate to open, which will also help ensure safety preventing people from entering a closed level crossing.View full abstractDownload PDF (801K) -
Kazuo Tanabe2009 Volume 129 Issue 8 Pages 507-512
Published: August 01, 2009
Released on J-STAGE: August 01, 2009
JOURNAL FREE ACCESSThe audible noise produced by corona discharge from AC overhead transmission line conductors is one of the major factors affecting the design of conductors, particularly for transmission lines with voltages above 500 kV. The audible noise has two components, which are random noise with frequency components from several hundreds to 20 kHz and pure tones with a power line frequency and frequency components of its even multiples.
In this paper, measurement results for random noise in heavy rain using a real-scale facility, namely, UHV corona cage, which has a cross section of 8 m×8 m and a length of 24 m, are shown and a new prediction formula for the sound level of random noise in heavy rain is proposed.View full abstractDownload PDF (1240K) -
Akihide Shiratsuki, Tomohito Mori, Haruhiko Kohyama, Hajime Nakajima, ...2009 Volume 129 Issue 8 Pages 513-519
Published: August 01, 2009
Released on J-STAGE: August 01, 2009
JOURNAL FREE ACCESSBecause a contact travel can show a trend of operating condition of high voltage switchgears, it is utilized as an important parameter for not only monitoring or diagnostic system but also intelligent controls such as controlled switching systems to eliminate harmful switching transients. Potential meters or encoders are usually applied for this purpose, but it requires modification of moving parts that is not acceptable in some types of switchgears especially for retrofit work in fields.
This paper describes a development of a compact and isolated type travel sensor, which can be easily installed in switchgear cabinets, and evaluation test results using prototype mounted in actual switchgear.View full abstractDownload PDF (741K) -
Tetsuo Fukuchi2009 Volume 129 Issue 8 Pages 520-524
Published: August 01, 2009
Released on J-STAGE: August 01, 2009
JOURNAL FREE ACCESSFlame detection is important for prevention of spreading of accidental fires. When combustible gas is ignited under daylight conditions, the flame is often difficult to detect by conventional imaging because of the high background radiation. The flame can be visualized by selectively detecting the emission of the OH radical, which is present in hydrocarbon or hydrogen flames. By detecting the OH radical emission in the solar blind region of wavelength below 290 nm, the background radiation can be effectively eliminated. In this study, an experimental device for visualization of flame at wavelength 285 nm was constructed. A combination of two narrowband interference filters was found to be sufficient to eliminate background radiation and selectively image the OH emission. The device could detect butane burner flame under daylight conditions.View full abstractDownload PDF (941K) -
Yoshitaka Nakamura, Takeshi Morimoto, Tomoo Ushio, Zen-Ichiro Kawasaki2009 Volume 129 Issue 8 Pages 525-530
Published: August 01, 2009
Released on J-STAGE: August 01, 2009
JOURNAL FREE ACCESSLightning Research Group of Osaka University (LRGOU) has been developing two- (2D) and three-dimensional (3D) VHF source mapping system for electromagnetic (EM) waves emitted associated with lightning discharge progression based on a unique technique of the broadband digital interferometry. The spatial accuracy of the interferometer is influenced by its installation errors. In this paper, we propose a simplified calibration of these installation errors using broadcast waves, and assess spatial accuracy of the interferometer after removal of installation errors.View full abstractDownload PDF (961K) -
Satoru Arakawa, Sunao Ronte, Takahiro Otsuka, Hideyuki Aso, Masaharu U ...2009 Volume 129 Issue 8 Pages 531-536
Published: August 01, 2009
Released on J-STAGE: August 01, 2009
JOURNAL FREE ACCESSAn Amplitude Probability Distribution (APD) measuring receiver that conforms to CISPR16-1-1 2nd edition has been developed. The receiver is installed in a general-purpose spectrum analyzer that has a field programmable gate array (FPGA) for digital signal processing. This paper reports the evaluation test results for measuring continuity, the results of an examination of the accuracy on the peak measurement of pulses that occur infrequently, and the results of an APD measurement experiment on rarely occurring pulses mainly caused by electrostatic discharge.View full abstractDownload PDF (847K) -
Seishiro Ishii, Syuji Sayama2009 Volume 129 Issue 8 Pages 537-542
Published: August 01, 2009
Released on J-STAGE: August 01, 2009
JOURNAL FREE ACCESSIt was reported that various radar clutters obey a Weibull distribution under certain conditions. To suppress such Weibull-distributed clutter, a new adaptive method was proposed by the present authors. In this method, the parameters of the Weibull distribution and the threshold level for an adaptive Constant False Alarm Rate (CFAR) detector are determined by calculating the variance after it passed through a logarithmic amplifier. To apply this new method to practical problems observed by an S-band radar, computer simulation were made for a finite number of samples in order to obtain the CFAR maintenance in Weibull radar clutter which was including sea clutter and ground clutter from a variety of terrain near the port. Finally an improvement value of target-to-clutter ratio 49.5dB was obtained for the detection of ships embedded in sea clutter near the port.View full abstractDownload PDF (1257K) -
Eiichiro Momma, Hiromitsu Ishii, Takashi Ono2009 Volume 129 Issue 8 Pages 543-548
Published: August 01, 2009
Released on J-STAGE: August 01, 2009
JOURNAL FREE ACCESSIn this paper, rocks which contain some degrees of weathering are classified by a rock type using the support vector machine based on feature parameters of a boring core sample image. The feature parameters were determined based on visual features of the rocks. From a histogram of the image, the median value and the inter quartile range were used as feature parameters. From a co-occurrence matrix of the image, “angular second moment”, “correlation” and “information measures of correlation1 and 2” were used as features. The classification considered nonlinear separation by the support vector machine. A percentage of correct answers were about 71-86% on a test by a cross validation. In conclusion, it is shown that I1I2I3 color space and textural features are suitable for describing the rock type, and the rock type can be classified using the support vector machine with the feature parameters of color vectors and textural parameters.View full abstractDownload PDF (16074K)
Paper
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Yoshihiro Konishi2009 Volume 129 Issue 8 Pages 549-554
Published: August 01, 2009
Released on J-STAGE: August 01, 2009
JOURNAL FREE ACCESSTightly coupled lines are widely used for wide band directional couplers, filters and baluns(1)(2). Though the phase velocity of TEM modes constructed in the uniform medium takes the equal values, the coupled line made on the surface of the dielectric substrate, however, are often used to make it easy. Sometimes, the technologies are used for the band pass filter and others. In this case, the phase velocity of eigen modes such as an even mode and odd mode take the different values, and the performance of the circuits using the coupled line are quite deteriorated. This paper, therefore, proposes the technology to give the delay function for either mode such as the even mode for the symmetrical coupled line to make same values of both eigen modes. Especially, the directional coupler of two microstrip lines coupled through the aperture with step impedance of the even mode are shown with the design theory and the experimental results comparing without step impedance.View full abstractDownload PDF (965K) -
Kazunori Moriki, Motoshige Yumoto2009 Volume 129 Issue 8 Pages 555-561
Published: August 01, 2009
Released on J-STAGE: August 01, 2009
JOURNAL FREE ACCESSPlasma enhanced polymerization is an attractive technology to fabricate an optical polymer waveguide, because it has capability to provide an uniform thickness film on a substrate with various surface geometry, and to provide change of refractive index by controlling a proportion of source monomer mixing. In the present paper we discuss optical constants and molecule structures of the films added hetero-atoms, O, N and F in the CHx network of polymer. Refractive index of those films changes from 1.52 to 1.63 at 1.0 μm wavelength, depending on the variety of hetero-atoms. Fluorine atoms added into a film decreases refractive index of the film. Oxygen atoms added into a film, which form ester structure (- COO-), decrease refractive index of the film, and some O atoms token into a film as OH base will increase optical absorption in inferred region for optical communication. Nitrogen atoms added increase optical absorption due to forming NH2 base. Finally, sp3/sp2 fraction controlling in the film will be a suitable to control refractive index of the film for an optical waveguide, for example by using mixed monomer of C6H6 and C6H10.View full abstractDownload PDF (834K)
Letter
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Haruo Itoh, Susumu Suzuki, Kenji Teranishi, Naoyuki Shimomura2009 Volume 129 Issue 8 Pages 562-563
Published: August 01, 2009
Released on J-STAGE: August 01, 2009
JOURNAL FREE ACCESSRegularly arrayed patterns of microdischarge light in dielectric barrier discharge (DBD) and dark spots surrounding glow-like discharge on the dielectric electrode are found in the self-organization phenomenon (SOP). The discharge is generated using a piezoelectric transformer (PT) in the Ar/air mixture. Time-resolved images are captured with an ICCD camera during one cycle of a sinusoidal applied voltage and the voltage-current waveforms are recorded using an oscilloscope. The observed dark spots are the traces of the accumulated charges by the DBD on the dielectric electrode and are considered as the sources of initial charges that induce the next microdischarge development, resulting in the hexagonally-arranged discharge spots.View full abstractDownload PDF (471K)
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