The geometrical characteristics analysis of grain is the important base of metallographical analysis. 晶粒的几何特征度量是金属性能分析的重要基础。
Based on the geometry characteristics of Bertrand surfaces, the complicated surface conjugation issue can be discussed with their directrix line. 基于白川德曲面的几何特征，将复杂的曲面共轭问题归结到准线上来讨论。
