Yulin city is an important national base of heavy-chemical engineering, and an extremely vulnerable area as well.

陕北榆林市既是我国重要的能源重化工基地，又是生态环境极端脆弱的危急区。

It became a bit wider, but at the same time the cupola vulnerable area was almost completely removed. As a result, the total vulnerable area remains the same.

除了变得宽了一点点而已，但是与此同时曾经作为弱点的观察塔区域被移除了。

The most vulnerable area of the vertical steel oil tanks being destroyed is the bottom shell, because the variables acting on it are random, reliability analysis can be applied in assessment.

立式钢油罐强度破坏的重点区域在底圈罐壁，其作用的各变量因素具有较大的随机性，可靠性评价方法较为适用。