| Project/Area Number |
16310122
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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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, Associate Professor (20301947)
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| Co-Investigator(Kenkyū-buntansha) |
KOSE Katsumi University of Tsukuba, Graduate School of Pure and Applied Sciences, Professor (60186690)
SAKUMA Atsushi Tokyo University of Agriculture and Technology, Institute of Symbiotic Science and Technology, Associate Professor (60274180)
NOJO Ayumu Hokkaido University of Education, Faculty of Education, Associate Professor (20311524)
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| Project Period (FY) |
2004 – 2006
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| Project Status |
Completed (Fiscal Year 2006)
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| Budget Amount *help |
¥15,700,000 (Direct Cost: ¥15,700,000)
Fiscal Year 2006: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 2005: ¥1,800,000 (Direct Cost: ¥1,800,000)
Fiscal Year 2004: ¥12,800,000 (Direct Cost: ¥12,800,000)
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| Keywords | Sea spray icing / Natural disaster / Crystal growth / Imaging / Magnetic Resonance Imaging / MIR / 核磁気共鳴 / 海水飛沫着氷 / ブライン / 3次元構造 / 排水路 / 船体着氷 |
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| Research Abstract |
Sea-spray ice accretion is a major problem for the operation of lighthouses in northern harbors. Brine pockets trapped in spray-ice matrices during wet growth are one of the structural features of sea-spray icing, and brine drainage control, one of the physical properties of spray ice. We have developed a compact NMR imaging system set up in a cold room to maintain the sample at a constant temperature.
The system consists of a permanent magnet, a gradient coil set, and an RF probe installed in -5 °C cold room. A compact MRI console was set up at room temperature beside the cold room. The permanent magnet is a yokeless magnet with the following specifications: field strength= 1.04 T, gap width= 60 mm, homogeneity= 15.3 ppm over 30 mm DSV at 25 °C, and weight= 300 kg. The RF coil is a 30-mm-diameter ten-turn solenoid.
We obtained sea-spray icing samples from the ice accretion on a lighthouse on the west coast of Hokkaido, Japan. Because the brine in the spray ice had drained out, using a suction pump, we filled the air gaps in the drainage channels with dodecane (C_<12>H_<26>). The signal from dodecane doped with iron acetylacetonate (C_<15>H_<21>O_6Fe) was sufficient to detect the location of the drainage channels.
A three-dimensional driven equilibrium spin-echo (3D-DESE) sequence (repetition time (TR)/echo time (TE) = 200 ms/8 ms, image matrix= 256^3, voxel size=(123 μm)^3, total imaging time= 16 h, NEX= 4) was used for 3D high-resolution imaging. Since the NMR signal from the ice was negligible compared with that from dodecane, the drainage channels appeared as bright regions.
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