| Project/Area Number |
13680541
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Natural disaster science
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| Research Institution | Hokkaido University of Education |
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Principal Investigator |
OZEKI Toshihiro Hokkaido University of Education, Faculty of Education, Iwamizawa Campus, Associate Professor, 教育学部・岩見沢校, 助教授 (20301947)
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| Co-Investigator(Kenkyū-buntansha) |
NISHIMURA Koichi National Research Institute, Snow and Ice Research Group, Senior Researcher, 長岡雪氷防災研究所, 主任研究員 (10180639)
KOSE Katsumi University of Tsukuba, Institute of Applied Physics, Professor, 物理工学系, 教授 (60186690)
NOJO Ayumu Hokkaido University of Education, Faculty of Education, Iwamizawa Campus, Associate Professor, 教育学部・岩見沢校, 助教授 (20311524)
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| Project Period (FY) |
2001 – 2003
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| Project Status |
Completed (Fiscal Year 2003)
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| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2003: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 2002: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 2001: ¥2,000,000 (Direct Cost: ¥2,000,000)
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| Keywords | Magnetic Resonance / Sea Spray Icing / Imaging / Three Dimensional Structure / MRI / Spongy Ice / Ship Superstructure Icing / Lighthouse |
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| Research Abstract |
Reduced visibility due to sea-spray ice accretion is a big problem for the operation of lighthouses in northern harbors. Spray icing also causes marine disasters for trawlers and vessels in cold sea areas. Brine pockets, which are trapped in a spray ice matrix during ice growth from sea spray, are structural feature of the sea-spray icing. The salt entrapment and drainage of the brine controls the growth rate and physical properties of spray ice. To address this problem we designed an MR microscopy system to visualize the drainage channels in sea spray icing.
The sea spray icing samples came from ice accretion on a lighthouse on the west coast of Hokkaido, Japan. Because the brine in the spray ice had already drained out, we used a suction pump to fill the air gaps in the drainage channels with dodecane. The signal from dodecane doped with iron acetylacetonate was sufficient to detect the location of the drainage channels.
3-D microscopic images were obtained with an NMR imaging system. The imaging sequence used 3-D gradient echoes. To obtain one 3-D image, 0.5 -1 h was needed ; thus, we used a specimen-cooling system to maintain the sample at a constant temperature. The chamber had a double-pipe cylinder through which flowed cold air, and the temperature of the sample holder was controlled by adjusting the volume of cold air flow.
We used MIP and 3-D rendering to visualize the drainage channels, and then we recognized that sea spray icing has a developed network structure of drainage channels. This experiment shows that MR microscopy can be used to image the structure of drainage channels in sea spray ice.
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