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Volume 61 (1999)
- Issue 6 Pages 437-
- Issue 5 Pages 369-
- Issue 4 Pages 285-
- Issue 3 Pages 197-
- Issue 2 Pages 115-
- Issue 1 Pages 3-
Volume 61, Issue 2
Displaying 1-4 of 4 articles from this issue
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Part 1: Determination of c-axis orientation by a new image analysisYun WANG, Nobuhiko AZUMA, Seiji KAMIMURA1999 Volume 61 Issue 2 Pages 115-126
Published: March 15, 1999
Released on J-STAGE: August 07, 2009
JOURNAL FREE ACCESSIn order to determine c-axis orientations of individual grains in a thin section of polycrystalline ice, a new method by image analysis technique has been developed. Images of ice thin section placed between rotating crossed polaroids are recorded with three CCD (Charge Coupled Device) cameras. One camera is set in a vertical position and the others are inclined 20 degrees with respect to the vertical axis. From the image intensity (gray value) data of each crystal in the thin section, the extinction angles of individual crystals can be determined. The c-axis orientation of an ice crystal can be calculated with the geometrical relation of the extinction angles with respect to three cameras. In order to verify this method, experiments using quartz specimens with different tilt angles of c-axes were carried out. A quadrant judgment method was developed to reduce miscalculation of c-axis orientations. By the combination of four sets of extinction angles with respect to four inclined CCD camera positions, the c-axis azimuth and tilt angle can be determined accurately.View full abstractDownload PDF (7413K) -
Part 2: Automatic analysis of ice fabric and texture by image-processing techniqueYun WANG, Nobuhiko AZUMA1999 Volume 61 Issue 2 Pages 127-138
Published: March 15, 1999
Released on J-STAGE: August 07, 2009
JOURNAL FREE ACCESSAn automatic ice fabric analyzer has been developed to determine individual c-axis orientations by image-analysis technique. The analyzer consists of four major components: a sample stage, a pair of crossed polaroids, a CCD (Charge Coupled Device) camera and a light source. Both the sample stage and the crossed polaroids can be rotated independently by the stepping motors controlled by a personal computer. Measurements are conducted as follows: an ice thin-section is set on the sample stage, then the crossed polaroids are rotated while the thin section images are fed into the personal computer at intervals of 2 degrees of rotation. From the image intensity (gray value) data set of each crystal in the thin-section, the extinction angles of individual crystals are determined. Similarly, eight other extinction angles of individual crystal are obtained from eight CCD camera positions with respect to the thin section. Finally, the c-axis orientation of individual crystal is calculated from these extinction angles. With this technique, c-axes of all crystals inside the view of the CCD camera are automatically analyzed within a short time (about 20 min.), together with the data of grain size, grain shape and other parameters.View full abstractDownload PDF (8000K) -
Kyo MATSUDA, Takashi YAJIMA, Masato SHIBUYA1999 Volume 61 Issue 2 Pages 139-147
Published: March 15, 1999
Released on J-STAGE: February 05, 2010
JOURNAL FREE ACCESSTree saplings were planted in 1977 on a slope covered by Sasa bamboo in the Teshio Experiment Forest of Hokkaido University to prevent snow avalanches occuring every year and to restore the natural landscape of the slope. Before the planting, Sasa densely covering the slope was pruned away and short wood stakes were rammed in the upper part of the slope, and saplings of Abies, Picea and two species of Larix were planted in the slope. Then the slope was protected from snow avalanches in the following years, probably by effects of sasa-clearing and wood stakes, and the growth of saplings resulted in the reestablishment of a forest stand. After 19 years of the planting, mean heights of Larix, Abies and Picea attained 12, 7 and 4 m, respectively. Avalanches on the slope never occurred from 1978 to the present. Natural broad-leaved trees such as Quercus and Tilia species, which were inhibited their growth by the avalanche, also regained vigorous growth and attained their maximum height over 7 m. Present small patches on the slope are mixed stands of conifers and braodleaved trees. An overall discussion is given on the introduction method of trees to the slope with deep snow, especially from aspects of landscape restoration and expected costs.View full abstractDownload PDF (4964K) -
Kazushige NAGASHIMA, Yoshitaka YAMAMOTO, Yoshinori FURUKAWA1999 Volume 61 Issue 2 Pages 149-154
Published: March 15, 1999
Released on J-STAGE: February 05, 2010
JOURNAL FREE ACCESS
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