Under these conditions, the yarn trajectory projection was simulated as the Archimedean screw in the interior region or the circular arc in the surface region and characterized with a corresponding mathematical formula.

• 在此基础上,分别用阿基米德螺旋线段和圆弧段近似预成型内部与表面的纱束轨迹投影,并给出相应的数学描述。