In the 17th century , the chinese southeast coastal region took the lead in a structural transformation for transitioning into commodity economy from a traditional self - sufficient natural economy to the one with overseas - orientation 摘要17世纪,中国东南沿海率先展开了由传统自给自足自然经济向以海洋经济为导向的商品经济过渡的结构性转型。
In order to approach the optimum design of changeover portion structural shapes for submarine ' s different diametral pressure cabins , a new structural type , named the double arc transition form , is introduced based on the analysis of stress concentration , by using the engineering calculation method and finite element mthod 摘要为了探讨潜艇不同直径的耐压舱室过渡段结构型式的最优设计,利用工程计算方法和有限元方法,分析过渡段结构的应力集中,提出了能够使不同直径圆柱壳光滑过渡的结构形式双圆弧式过渡形式。