请教帮助手册中的轮胎部分inp问题

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最近在看英文帮助Abaqus Example Problems Manual，Steady-state rolling analysis of a tire,” Section 3.1.2，在rollingtire_brake_trac.inp这个文件中，

这个*TRANSPORT VELOCITY
NTIRE, 8.0 速度是怎么确定的呢？

A wheel in free rolling, traction, or braking will spin at different angular velocities, file:///D:/SIMULIA/Documentation/docs/v6.9/books/exa/graphics/exa_eqn00420.gif, for the same ground velocity, file:///D:/SIMULIA/Documentation/docs/v6.9/books/exa/graphics/exa_eqn00530.gif Usually the combination of file:///D:/SIMULIA/Documentation/docs/v6.9/books/exa/graphics/exa_eqn00420.gif and file:///D:/SIMULIA/Documentation/docs/v6.9/books/exa/graphics/exa_eqn00531.gif that results in free rolling is not known in advance. Since the steady-state transport analysis capability requires that both the rotational spinning velocity, file:///D:/SIMULIA/Documentation/docs/v6.9/books/exa/graphics/exa_eqn00420.gif, and the traveling ground velocity, file:///D:/SIMULIA/Documentation/docs/v6.9/books/exa/graphics/exa_eqn00531.gif, be prescribed, the free rolling solution must be found in an indirect manner. One such indirect approach is illustrated in this example. An alternate approach involves controlling the rotational spinning velocity using user subroutine UMOTION while monitoring the progress of the solution through a second user subroutine URDFIL. The URDFIL subroutine is used to obtain an estimate of the free rolling solution based on the values of the torque at the rim at the end of each increment. This approach is also illustrated in this example.

除了子程序还有什么可以确定的呢？