散乱点云数据的曲率估算及应用

提出一种直接在散乱数据点云上计算曲面的局部微分性质,包括平均曲率、高斯曲率和主曲率。首先,计算各点的邻近点集,选取合适的局部基础曲面,把邻近点集投影到相应的局部基础曲面。然后,在以局部基础曲面内投影点的参数化代替空间邻近点集的参数化的基础上,用二次参数曲面逼近空间邻近点集,从而计算出各点的法矢,再对不协调的法矢方向进行调整。最后,利用曲率公式计算出各点的曲率。试验表明这种方法可以较好反映曲面的特征。运用该曲率算法对海量数据进行了简化。

Local corrosion mechanism of SiO2-based refractories caused by slag movement near solid–liquid–gas interface in different slag systems

Slag movement on SiO2-based prism refractories in different slag systems was observed. The cross section shape evolution mechanism was discussed. Two types of shape evolution appear. For PbO-SiO2 slag whose surface tension improves with SiO2 concentration, slag film flows up along four edges under axial Marangoni shear force and wettability. Then, it flows down along four lateral faces under gravity. Corrosion rate at edges is larger than that on lateral faces due to different SiO2 solubilities of ascending and descending flow. Prism cross section shape changes from square to round. For FetO-SiO2 slag whose surface tension reduces with the increase of SiO2 concentration, slag film flows up under the inflence of wettability. Then, it flows down under Marangoni shear force and gravity. Compared to four edges, slag is mainly up and down on four lateral faces due to larger surface tension and size. So, prism cross section shape keeps square.