巻号一覧
11 巻, Supplement1 号
選択された号の論文の53件中51～53を表示しています
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岡本 孝司, 班目 春樹, 塩谷 隆二1991 年 11 巻 Supplement1 号 p. 189-192
発行日: 1991/07/01
公開日: 2009/07/31
ジャーナル フリーIn order to measure the velocity distributions in a tank using VTR images, a new image processing algorithm was developed, in which the expert system was used. The histogram of candidate velocity vectors was constructed. The correct vector density became larger than the false vector density in the velocity vector histogram, consequently the most probable vector was defined. The histogram was re-constructed using the information of the probable vector in order to reduce the noise and to improve the accuracy of the velocity data. For this re-construction, the method of the expert system is introduced in order to select the feed back parameters. Using this algorithm, the velocity fields could be obtained even from noisy images. The present algorithm was applied to the two-dimensional flows in a thin rectangular tank with free surface and the three-dimensional flows in a open channel, showing high effectiveness and high extensiveness.抄録全体を表示PDF形式でダウンロード (227K) -
近江 和生, 植村 知正, 山本 富士夫1991 年 11 巻 Supplement1 号 p. 193-196
発行日: 1991/07/01
公開日: 2009/07/31
ジャーナル フリーTwo types of image-processing velocimetry are tested and compared on the basis of two-dimensional wakes behind a cylindrical body. Both methods make use of tracer particles suspended in water and aim to estimate quasi instantaneous distribution of velocity. However the first one is particle-streak velocimetry which determines velocity vectors from the length and the gradient of particle streaks traced during a given time of exposure, and the second one is particle-tracking velocimetry in which the velocity is determined by a particle pursuit program operating between two sequential image frames. From among a number of pursuit algorithms required for the second velocimetry, the binary correlation method developed by the authors is employed in the present study.抄録全体を表示PDF形式でダウンロード (2238K) -
佐田 豊, 笠木 伸英, 善本 英夫1991 年 11 巻 Supplement1 号 p. 197-200
発行日: 1991/07/01
公開日: 2009/12/08
ジャーナル フリーA new digital image processing system was constructed for three-dimensional particle tracking velocimetry, it consists of three TV cameras, three laser disk recorders, and a digital image processor interfaced with a graphic work station. A set of three images simultaneously taken by the cameras can be recorded consecutively at a 1/60s or 1/30s interval. A technique of particle path reconstruction over two to four time steps is introduced. A particle is. tracked by finding the particle in a search region around the particle's new position which is estimated from the preceding particle positions. The size of the search region must be large enough to capture all possible particle motions and, at the same time, smaller than the average particle distance to execute data processing efficiently. The optimization of this search region size is presently analyzed using the Lagrangian time spectra of velocity fluctuation. Computer simulations are also performed to evaluate effectiveness of the multiple time-step particle path reconstruction technique with modeled Lagrangian spectra of isotropic homogeneous turbulence.抄録全体を表示PDF形式でダウンロード (215K)