convexity of yield surface

例句：

1. 1. The shape of the surfaceis very convex.
   这个表面的形态非常凸。
2. 2. The geometry of the lens isdetermined by its convexity.
   透镜的几何形状由其凸度决定。
3. 3. Thecurved surface of the car is dueto its high convexity.
   汽车的曲面是由于其高凸度造成的。