Part of such planetesimals entered the asteroid region, drew out most of the matter there, and increased the randomvelocity of the asteroids that remained, so they could not combine to form a planet.
It generates small particles with random size and velocity and lets them fall onto the surface where they settle, increasing surface height in the place a bit.
它产生随机大小和速度的小粒子，让它们落到图像表面上，使图像产生表面高度小小渐增的效果。
3
The wind loading of a tracking radar antenna, for example, results from a mean velocity component that varies with time plus superimposed random gusts.