理论上，一个无摩擦力的，或者说是理想的机器，输入和输出的功相等，因此效率是1，或者说是100%。

In a theoretically frictionless, or ideal, machine, the work input and work output are equal, and the efficiency would be 1, or 100%.

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永动机只能是一种无摩擦力的机器。

A perpetual motion machine would have to be frictionless.

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本文提出了一种基于迭代技术的边界元法求解三维无滑动摩擦型弹性接触问题。

A boundary element method based on an iterative technique for solving the three-dimensional elastic contact problem without sliding is presented.

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Somehow, if you could manufacture a really smooth frictionless surface, that if you took a hockey puck or something and an air cushion and you give it a push, in some idealized world, it'll travel forever.

如果你制造一个绝对光滑无摩擦的表面,然后在上面放个冰球或者别的什么,或者气垫,然后推它一下,在理想条件下,它会永远运动下去

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