In addition, the Grads Field Price Effect Model put forward by Zen Fanyin is modified. 此外，对曾凡银提出的绿色壁垒价格梯度场模型进行了修正，通过对修正模型的分析，验证了绿色壁垒在价格上对关税壁垒的替代效应。
In the light of the inwall depression in the process of tubular intermediate upseting, a parallel velocity field model with depression is established. 针对管坯中部锻锻变形过程中产生的内壁凹陷现象，建立了含凹陷的平行速度场模型。
