Methods Liver scanning was performed with a high frequency transducer to measure the velocity acceleration time and resistant index of portal vein and hepatic artery after finishing the anastomosis.
方法选用高频手术专用探头，于手术中门静脉、肝动脉吻合完成后立即测量肝动脉及门静脉血流速度，并计算快速充盈时间及阻力指数。
Acceleration and velocity are both vectors.
加速度和速度都是矢量。
So notice that the acceleration is constant in time, is not changing but the velocity is changing.
请注意此处的加速度，是一个常数，不随时间变化而变化，不过速度是变化的。
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？
I now would like to write down, in most general form the equation for the position and the velocity as a function of time for a one-dimensional motion whereby the acceleration is constant.
我来把更一般的形式，写出来吧，在一维空间中，位置和速度，作为时间函数的，一般形式，这里的加速度是一个常数。
And, we've also learned about acceleration, which is the derivative of velocity.
我们还学过加速度，也就是速度向量的导数。
That is the analog of force divided by mass equals acceleration, which is d over dt of velocity.
这个类似于，力除以质量等于加速度，就是速度对t的导数。
So, the definition will take effect. The acceleration is as a vector, and the acceleration vector is just the derivative of a velocity vector.
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。
This is the position, this is its velocity and this is its acceleration.
这是位置，这是速度,然后是加速度。
Velocity is a vector and acceleration is a vector and today we're going to learn how to work with these vectors.
速度是个矢量，加速度也是个矢量，今天要来学学，如何处理矢量。
And angular acceleration is the derivative of angular velocity.
角加速度等于，角速度的导数。
Torque divided by moment of inertia is what will cause the angular acceleration, namely the derivative of angular velocity.
扭矩除以转动惯量,就会引起角加速度，也就是角速度的导数。
Ok, so let me move on a bit and point out that with parametric equations, we've looked also at things like velocity and acceleration.
再来深入研究一下参数方程，我们以前还学过速度和加速度的。
We want to go to the acceleration at any moment in time just the way we did that with velocity.
关于任意时刻的，加速度，和讲速度的时候一样。
So the signs in the velocity and the signs in average acceleration depend crucially on how I have defined my increasing value of x not where I choose my zero points.
所以速度的符号,和平均加速度的符号,这二者都取决于,这里x正方向,是如何定义的,和0点的选取没有关系。
Here the velocity is increasing so the acceleration must 0 be larger than zero here.
在这里速度在增加，所以加速度，肯定大于。
The average acceleration 2 between time t1 and time t2 2 would then be the velocity at time t2 minus the velocity at time t1, divided by t2 minus t1.
在t1和t2之间的，这段平均加速度2，等于t2时刻的速度2，减去t 1时速度，再除以。
However, if you take the average acceleration t1 0 that is smaller than zero 0 because here the velocity is zero but here the velocity is negative.
可是如果考虑到,和t5之间的平均加速度5，between，t1，and，t5,那么它将小于,因为这里速度为,但是到了这里却是负值。
Of course, you also get an acceleration here at this point, because there's also a change in velocity.
当然，在这一点，也有一个巨大的加速度，因为速度在这里也发生了变化。
This acceleration that is necessary to make the change in the velocity vector is always pointing towards the center of the circle.
要促使速度矢量，产生如此的变化，所需的加速度，总是指向圆心。
Acceleration: the rate of change of velocity.
加速度：速度变化的比率。
Third-order profile generation with on-the-fly velocity, acceleration, jerk and target position changes.
三阶剖面一代对-飞行速度，加速度，反射和目标位置的改变。
Objective To confirm clinical significance of wall motion velocity and acceleration measured by LEJ-1 omni-directional M-mode echocardiography (OME).
目的证实LEJ - 1型全方向m -型超声心动图测量心室壁运动速度与加速度的临床意义。
The velocity increasing, the acceleration of a body is positive.
速度增大时，物体的加速度是正的。
Through the theoretical deduction, the Kinematic equation, the velocity equation and the acceleration equation of the diamond wire saw during the manufacturing process are obtained.
通过理论推导得出了金刚石线锯加工过程的运动方程、速度方程和加速度方程。
Learn about velocity and acceleration vectors.
了解速率和加速度向量。
See the velocity and acceleration vectors change as the ball moves.
看看球移动时速率和加速度向量的变化。
Learn about position, velocity, and acceleration graphs.
了解位置、速率和加速度图。
Finally, computer simulation is applied to get the displacement, velocity, acceleration and tension of the anyplace on the scraper conveyor for the four special working condition.
对四种非稳定工况下的动态特性进行计算机仿真，得出整个刮板输送机在任意点的位移、速度、加速度和动张力。
Finally, computer simulation is applied to get the displacement, velocity, acceleration and tension of the anyplace on the scraper conveyor for the four special working condition.
对四种非稳定工况下的动态特性进行计算机仿真，得出整个刮板输送机在任意点的位移、速度、加速度和动张力。
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