该系统采用了智能标签、摄像机与路边传感器的集合，投入使用后，瑞典首都的交通量下降了近20%。

After the system—which uses a combination of smart tags, cameras and roadside sensors—was launched, traffic in the Swedish capital decreased by nearly 20%.

youdao

它可以对任一个小平面使用-，比如说对于这条曲线的线积分，等于通过这个曲面的旋度通量。

What it says on each small flat piece — it says that the line integral along say, for example, this curve is equal to the flux of a curl through this tiny piece of surface.

youdao

有一个和散度定理很像的东西，当然，对于通量和div, f的二重积分，都可以使用类似的理论。

There is a similar thing with the divergence theorem, of course, with flux and double integral of div f, you can apply exactly the same argument.

youdao