NMR Imaging of 3-D Snowpack Structures

3D 积雪结构的 NMR 成像

• 批准号: 11640423
• 负责人: NARITA Hideki
• 金额: $ 2.3万
• 依托单位: Hokkaido University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1999
• 资助国家: 日本
• 起止时间: 1999 至 2001
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-11640423/
• 关键词: NMR imaging; Snow pack; 3D-Visualization; 3D structures; Ice spheres; Depth-hoar crystals; しもざらめ雪; しまり雪

Microstructure of the snow pack should be better understood because it affects the mechanical and physical properties of snow. Thin sections and plane-surface sections are currently used to investigate. However, they give only two-dimensional information ; therefore, a large number of operations are necessary to reconstruct the three-dimensional structure. In this study we have developed a NMR imaging technique to visualize and quantify the 3D structure of snow pack.Because the NMR signal from the ice was very weak, the air spaces in the snow were filled with dodecane doped with iron acetylaetonate C12H26, which has a good infiltration property and a low freezing point (about -12℃). Thus, the NMR images the space occupied with dodecane instead of ice particles. The 3D images were obtained with a homebuilt NMR imaging system using a 4.74-T superconducting magnet. The result of test imaging of dodecane showed 0.5 to 2 hours were needed to obtain the one 3D image, and hence we developed a specimen cooling system to keep the temperature below 0℃. This system has a double-pipe cylinder made of acrylic plastic with outer diameter of 40 mm and inner diameter of 20 mm through which cold air was passed. Two types of snow were prepared : ice spheres of about 3-mm diameter and depth-hoar crystals. In particular, because the ice spheres are sufficiently large and uniformly sized, they were ideal for test imaging. 3D microscopic images were obtained successfully ; the image matrix was 128^3 and voxel size was 0.2 mm^3. We could recognize the 3D structure of the packed ice spheres clearly by viewing from various angles and cross sections.

雪包的微观结构应该得到更好的理解，因为它影响雪的机械和物理特性。薄切片和平面切片目前用于研究。然而，它们只给出二维信息;因此，需要大量的操作来重建三维结构。本研究利用核磁共振成像技术对积雪的三维结构进行了可视化和定量分析，由于冰的核磁共振信号很弱，因此在积雪的空隙中填充了具有良好渗透性和低凝固点（约-12℃）的乙酰丙酮酸铁（C12 H26）掺杂的十二烷。因此，NMR成像的空间被十二烷而不是冰粒占据。三维图像是用自制的核磁共振成像系统，使用4.74 T超导磁体获得的。十二烷的测试成像结果表明，获得一个3D图像需要0.5到2小时，因此我们开发了一个样品冷却系统，以保持温度低于0℃。该系统具有由丙烯酸塑料制成的双管圆柱体，其外径为40 mm，内径为20 mm，冷空气通过该双管圆柱体。准备了两种类型的雪：直径约3毫米的冰球和深度灰白色晶体。特别是，由于冰球足够大且大小均匀，它们是测试成像的理想选择。成功获得了3D显微图像;图像矩阵为128^3，体素大小为0.2 mm^3。从不同的角度和截面观察，我们可以清楚地识别出冰球的三维结构。

项目成果

T.Ozeki et al.: "NMR Imaging of Snow"Proceedings of International Snow Science Workshop 2000. (2001)

T.Ozeki 等人：“NMR Imaging of Snow”2000 年国际雪科学研讨会论文集。(2001)

尾関俊浩 他: "NMR映像法による積雪の可視化に関する一実験"寒地技術論文・報告集. 16. 132-136 (2000)

Toshihiro Ozeki 等：“利用核磁共振成像方法可视化降雪的实验”寒冷地区技术论文和报告集。16. 132-136 (2000)。

T. Ozeki et al.: "Visualization of Depth-hoar layers using NMR Micro-imaging"Proceedings of Cold Region Technology Conference. 17, (in Japanese). 104-109 (2001)

T. Ozeki 等人：“使用 NMR 显微成像实现深白层的可视化”寒冷地区技术会议论文集。

T. Ozeki et al.: "NMR Imaging of 3-D Snowpack Structures"Hokkaido-no-Seppyo. 19, (in Japanese). 18-20 (2000)

T. Ozeki 等人：“3-D 积雪结构的 NMR 成像”Hokkaido-no-Seppyo。

尾関俊浩 他: "MRIによる積雪3次元構造の可視化"北海道の雪氷. 19. 18-20 (2000)

Toshihiro Ozeki 等人：“使用 MRI 可视化 3D 雪结构”《北海道的雪与冰》19. 18-20 (2000)。