Journal of the Visualization Society of Japan
Online ISSN : 1884-037X
Print ISSN : 0916-4731
ISSN-L : 0916-4731
Volume 20, Issue 79
Displaying 1-11 of 11 articles from this issue
  • Shigeharu OHYAGI
    2000 Volume 20 Issue 79 Pages 297-302_1
    Published: October 01, 2000
    Released on J-STAGE: July 31, 2009
    JOURNAL FREE ACCESS
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  • A.Koichi HAYASHI, Yasunari MIKUTSU, Norio ARAKI
    2000 Volume 20 Issue 79 Pages 303-308_1
    Published: October 01, 2000
    Released on J-STAGE: July 31, 2009
    JOURNAL FREE ACCESS
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  • Shiro TAKI, Tomoaki YATSUFUSA, Ciheng ZHANG
    2000 Volume 20 Issue 79 Pages 309-314_1
    Published: October 01, 2000
    Released on J-STAGE: July 31, 2009
    JOURNAL FREE ACCESS
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  • Akiko MATSUO
    2000 Volume 20 Issue 79 Pages 315-320
    Published: October 01, 2000
    Released on J-STAGE: July 31, 2009
    JOURNAL FREE ACCESS
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  • Jiro KASAHARA, Toshi FUJIWARA, Takakage ARAI
    2000 Volume 20 Issue 79 Pages 321-326_1
    Published: October 01, 2000
    Released on J-STAGE: July 31, 2009
    JOURNAL FREE ACCESS
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  • Shigeru MATSUO, Toshiaki SETOGUCHI, Kenji KANEKO
    2000 Volume 20 Issue 79 Pages 327-332
    Published: October 01, 2000
    Released on J-STAGE: July 31, 2009
    JOURNAL FREE ACCESS
    Techniques using Coanda effect have been applied to the fluid control devices. In this field, experimental studies were so far performed for the spiral jet obtained by the Coanda jet issuing from a conical cylinder with an annular slit, thrust vectoring of supersonic Coanda jets and so on. It is important from the viewpoints of effective applications to investigate the characteristics of supersonic Coanda jet in detail. In the present study, the effects of pressure ratios and nozzle configurations on the characteristics of the supersonic Coanda jet have been investigated experimentally and numerically. In simula-tions, two-dimensional Navier-Stokes equation were solved using a 2nd-order TVD finite-volume scheme with a 3rd-order three stage Runge-Kutta method for time integration. As a result, the simulated flow fields were compared with experimental data in good agreement qualitatively.
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  • Kazuo OHMI, Hang-Yu LI, Hai Lam Dao
    2000 Volume 20 Issue 79 Pages 333-341
    Published: October 01, 2000
    Released on J-STAGE: July 31, 2009
    JOURNAL FREE ACCESS
    A new method of particle image detection has been implemented and tested for the use in the particle tracking velocimetry. The method benefits from a new algorithm of extracting individual particle images from a massive concentration of particles recorded in the PIV recordings. With this algorithm, the binary threshold level is determined particle by particle in such a way that the mean gray level of every particle is kept at a constant degree of contrast against the background. So the particles of any size, shape or gray levels are extracted. In addition, the algorithm is applicable to a variety of particle images, including those suffering from background noise. In the latter half of the paper, the new algorithm is further improved in order to speed up the computation and facilitate the estimation of the preset parameters.
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  • Ryozo HIRAKU, Toshio SUZUKI, Masahiro AZUMA, Yasuyuki TODA
    2000 Volume 20 Issue 79 Pages 342-349
    Published: October 01, 2000
    Released on J-STAGE: July 31, 2009
    JOURNAL FREE ACCESS
    Many researchers are improving PIV (Particle Image Velocimetly) or PTV (Particle Tracking Velocimetry) techniques to obtain three-dimensional velocity vectors. Most of the techniques with some reliability, however, needs expensive equipments or advanced measurement technologies. Especially for PTV techniques, high technologies are necessary to calibrate two or more cameras.
    In this paper, a technique to measure the three dimensional flow velocities with one camera are proposed to construct the instrumentation system with high practical use. The ideas of the spatial filter were combined with the laser sheet and acquire particle images using a high-speed video camera. The sampling speed of images might relate to the accuracy of measurement in this measurement method.
    Uniform flow fields are measured to calibrate this method and ±10% accuracy is obtained. Flow around a Delta-Wing is measured and compared with the velocity measured by 5-hole pitot tube. Good agreement is obtained between them.
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  • Atsushi NASHIMOTO, Nobuyuki FUJISAWA, Eiichi KIMURA, Tsuneo AKUTO
    2000 Volume 20 Issue 79 Pages 350-355
    Published: October 01, 2000
    Released on J-STAGE: July 31, 2009
    JOURNAL FREE ACCESS
    The method for measuring the shear stress distributions over a blade of rotating machinery is proposed by using the oil-film visualization technique combined with the image analysis. The visualization study is carried out in a water tank and the surface velocity of the oil-film over the blade surface is measured by applying the cross-correlation algo-rithm to a series of images with a certain pattern displacement. The transformation of surface velocity to shear stress is made by a well known shear stress distribution over a rotating disk in relation to the experimental surface velocity of oil film. The surface velocity of the oil-film and the centrifugal force effect are studied by using the flow over a rotating disk. The measurement of shear stress distribution over the fan blade is carried out over the fan blade at various operating conditions. The results indicate that the high-est shear stress appears along the blade tip at the design condition, while it is moved to the leading edge of the blade.
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  • Taro SEKINE, Masahiro TAKEI, Michiharu OKANO, Hiroyasu NAGAE, Yoshifur ...
    2000 Volume 20 Issue 79 Pages 356-364
    Published: October 01, 2000
    Released on J-STAGE: July 31, 2009
    JOURNAL FREE ACCESS
    Discrete wavelet transform has been applied to analyzing a driver's R-R Interval ta-chogram. Consequently, two specific wavelet levels indicate the dominant frequency that shows driver's mental stress with the time process. This visualization technique is able to replace the former analysis based on Fourier transform in driver's time-transient circum-stances. The experiments are carried out with a driver carrying an electrocardiograph in a passenger car circulating a test course with 140km/h. The R-R Interval tachogram was obtained from the driver before and while driving. The motivation behind this work is to establish a driver's mental model while a driver operates a vehicle. The model con-tributes to safety and comfortable driver's circumstances in road traffics.
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  • Masa-aki ISHIKAWA, Takehiro IDO, Yuichi MURAI, Fujio YAMAMOTO
    2000 Volume 20 Issue 79 Pages 365-372
    Published: October 01, 2000
    Released on J-STAGE: July 31, 2009
    JOURNAL FREE ACCESS
    The authors developed the velocity gradient tensor method (VGT) which was a PTV algorithm for measuring flow field as reported in a previous paper. When the VGT method is used, both the velocity vector and velocity gradient tensor can be obtained at each particle point. The purpose of this study is to propose a new technique for post-processing using the velocity gradient tensor in order to make a rearrangement of velocity vectors at particle points into those at grid points with a high spatial resolution. The per-formance of the processing method is examined by the vortex flow. It is made clear that the present method has high accuracy compared to conventional interpolation methods.
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