free element meaning in English

单体元素
未受攻击的机组
自由元素

The application of semantics is discussed as follows : the projection relation semantics leading to recognizing cylinder , the region semantics leading to recognizing linear sweeping , the free element semantics leading to recognizing the feature which the cylinder is cut by plane . last , a prototype system is developed according to the semantics model . the system can read dxf that contains 2d engineering drawing information and recognize the 3d feature
接着，根据工程语义模型表述，详细分析了各个类别、层次以及类别之间表达的工程语义的特点与内容，然后进行零件的特征分类，从特征识别的角度探讨了工程语义在图样理解的应用，并详细讨论了圆柱体、线性拉伸体、圆柱体的平面截切特征从投影语义、连通域语义、游离图元语义引导识别的应用过程。