它的局部是凸的，因为它没有环路，且曲率永远不会改变符号。

It is locally convex in the sense that it has no loops and the curvature never changes sign.

youdao

轻拍镜框上的滑轮构件挤压液体，从而改变薄膜的曲率聚焦远近不同的物体。

Flicking the slider mechanism built into the bridge squeezes the liquid, changing the curvature of the membrane to bring nearby or faraway objects into focus.

youdao

为了获取一个内焦距放大的图像，研究人员开动液压装置，改变透镜曲率，以协调方式改变检测器。

To achieve an in-focus and magnified image, the researchers actuate the hydraulics to change the curvatures of the lens and detector in a coordinated manner.

youdao