有必要对加速度给出一个严格的定义，加速度,作为一个矢量,是速度的一阶导数。

So, the definition will take effect. The acceleration is as a vector, and the acceleration vector is just the derivative of a velocity vector.

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本文的主要结论有：（1）二次二阶矩法是以一次二阶矩法为基础，并对一次二阶矩法的计算结果进行二次修正，在多数情况下有着更好的计算精度。

The main conclusions obtained in this thesis are as follow:(1) Based on FOSM, Second-order second-moment method modifies the results of FOSM, and has better calculation accuracy.

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研究了三阶Poincaré差分方程解的渐近性质。这种差分方程对应的常系数线性差分方程的特征方程有重根。

We studied the asymptotic behavior of solutions to third order Poincaré difference equation whose characteristic equation has multiple roots.

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Interestingly, only the first two derivatives have a name.

有趣的是,只有前两阶导数有名字

耶鲁公开课 - 基础物理课程节选

These are the things that we do best and where we have advanced course work available in these three categories and so I'm going to emphasize these three but we'll talk about all of these subjects as we go through the course.

这是我们做的最好的三个方向,在这三个方向下我们开设有高阶的课程,因此我会重点讲这三个方向,但随着课程的进行,所有的主题我们都会讲到

耶鲁公开课 - 生物医学工程探索课程节选

That there are two colors per strut, so what's linking the two backbones together are two colored segments that come from the outside towards the middle, and that the colors occur only in certain combinations, red and green, yellow and blue, that's all you see.

每个梯阶有两个颜色,主链是由,两种不同颜色的片段由外向内连接起来的,这些颜色仅以某种特定方式配对,红连接绿,黄连接蓝,大家都能看到

耶鲁公开课 - 生物医学工程探索课程节选