合理确定隧道顶板厚度是一项重要的研究课题。

How to determine reasonable subsea tunnel rock cover thickness is still an intractable research subject.

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由于缺乏防振橡胶制品的疲劳失效标准，因此，如何确定防振橡胶强化疲劳试验的参数就成为新的研究课题。

It is a new problem how to make sure these parameters to intensive fatigue experiments due to the lack of the standards of fatigue failures for the rubber materials.

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考虑到模糊模型与实际对象之间的误差，研究不确定模糊模型的模糊采样控制器的设计问题，也是一个很有挑战性的研究课题。

Considering the modeling error between fuzzy model and practical plant, it is a challenging issue to design fuzzy sampled-data controller for uncertain fuzzy systems.

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