为解决传统钢结构质量检测周期长、难度大、精度低等问题,本文融合BIM(Building Information Modeling)与三维激光扫描优势,提出了一种基于BIM+点云数据的钢结构质量智能检测方法。首先,依据工程图纸创建钢构件BIM;其次,利用三维激光扫...为解决传统钢结构质量检测周期长、难度大、精度低等问题,本文融合BIM(Building Information Modeling)与三维激光扫描优势,提出了一种基于BIM+点云数据的钢结构质量智能检测方法。首先,依据工程图纸创建钢构件BIM;其次,利用三维激光扫描技术获取钢构件逆向点云模型;基于PCA+ICP算法实现点云模型与BIM的自动化配准;最终,提出顾及点云粗糙度的法向量方向距离计算法,以法向量为方向计算点云与BIM模型的距离,实现了钢结构质量智能检测。为验证上述方法的有效性,将上述方法应用于中国人民大学通州新校区社会与人口学院楼项目,结果表明,点云与BIM模型配准精度能够控制在1 mm以内,距离计算在2 mm以内,说明本文提出的方法能够智能、高效的应用于钢结构质量检测。展开更多
Spine is the sharpest and hardest part of many plants, which contains highly aligned fiber cells. Here, we report the micro- structures and mechanical properties as well as their correlation of single spine fiber cel...Spine is the sharpest and hardest part of many plants, which contains highly aligned fiber cells. Here, we report the micro- structures and mechanical properties as well as their correlation of single spine fiber cells （SFCs） from the cactus Echinocactus grusonii. It is found that the SFCs are 0.32-0.57 mm in length and 4.6-6.0 gm in width, yielding an aspect ratio of 53-124. X-ray diffraction and Fourier transform infrared spectrophotometry show that the spine fiber is mainly made up of cellulose I with a crystallinity index up to -76%. Nanoindentation tests show that a natural spine presents a high modulus of -17 GPa. Removing hemicellulose and lignin from the SFC significantly reduces its modulus to -0.487 GPa, demonstrating the critical role of adhesives hemicellulose and lignin in affecting the mechanical properties of the SFCs. This finding sheds light on de- signing novel bio-inspired high-performance composite nanomaterials with aligned nanofibers, such as using hemicellulose and lignin as adhesive in making carbon nanotube fibers.展开更多
文摘为解决传统钢结构质量检测周期长、难度大、精度低等问题,本文融合BIM(Building Information Modeling)与三维激光扫描优势,提出了一种基于BIM+点云数据的钢结构质量智能检测方法。首先,依据工程图纸创建钢构件BIM;其次,利用三维激光扫描技术获取钢构件逆向点云模型;基于PCA+ICP算法实现点云模型与BIM的自动化配准;最终,提出顾及点云粗糙度的法向量方向距离计算法,以法向量为方向计算点云与BIM模型的距离,实现了钢结构质量智能检测。为验证上述方法的有效性,将上述方法应用于中国人民大学通州新校区社会与人口学院楼项目,结果表明,点云与BIM模型配准精度能够控制在1 mm以内,距离计算在2 mm以内,说明本文提出的方法能够智能、高效的应用于钢结构质量检测。
基金supported by the National Key Basic Research Program of China("973"program)(Grant Nos.2013CB932604,2012CB933403)the National Natural Science Foundation of China(Grant No.91023026)+2 种基金the Fundamental Research Funds for the Central Universities(Grant NosNP2013309,NS2012043)Jiangsu Planned Projects for Postdoctoral Research Funds(Grant No.1302015B)the NUAA Research Initiative for New Stuff(Grant No.1011-YAH13042)
文摘Spine is the sharpest and hardest part of many plants, which contains highly aligned fiber cells. Here, we report the micro- structures and mechanical properties as well as their correlation of single spine fiber cells （SFCs） from the cactus Echinocactus grusonii. It is found that the SFCs are 0.32-0.57 mm in length and 4.6-6.0 gm in width, yielding an aspect ratio of 53-124. X-ray diffraction and Fourier transform infrared spectrophotometry show that the spine fiber is mainly made up of cellulose I with a crystallinity index up to -76%. Nanoindentation tests show that a natural spine presents a high modulus of -17 GPa. Removing hemicellulose and lignin from the SFC significantly reduces its modulus to -0.487 GPa, demonstrating the critical role of adhesives hemicellulose and lignin in affecting the mechanical properties of the SFCs. This finding sheds light on de- signing novel bio-inspired high-performance composite nanomaterials with aligned nanofibers, such as using hemicellulose and lignin as adhesive in making carbon nanotube fibers.
