HHT has not been put forward for long time, so it contains some theoretical problems, such as envelop and mean curve fit, boundary effect, modes mix and so on.

HHT刚提出不久，其理论本身还存在不少问题，如包络线和均值曲线的拟合、边界效应和模态混叠等问题。

youdao

There are 6 interconnected crossing Bridges (one is preserved) and among them there is one special large bridge. The circular min mean curve is 1000 meters and the Max slope is 3%.

全线设有互通立交6处(其中一处预留)，特大桥一座，最小平曲线半径1000米，最大纵坡3%。

youdao

Here, when it makes this rounding curve the velocity is positive here, but on this side it's negative so what does that mean for the acceleration?

这里，就在曲线的拐角，速度一开始是正的，不过在另一边就成了负的，就加速度而言这又意味着什么呢？

youdao

And even when the engineering is perfect, Mars itself can throw mean curve balls.

MSN: History littered with failed Mars probes

He did, however, acknowledge that the huge amount of flexibility does mean that the learning curve is steeper.

ENGADGET

In a bell curve, the median and mean are the same.

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