故元

但由于历史的原因，该区域长期滞后的经济发展不可能在短时期内得到根本性改观，故其二元经济结构仍然存在。

However , owing to historical reasons , the long-term economic lagging couldn tbe change entirely , so its dual economy still existed .

分层破坏主要发生在层合板的界面层上，故界面元的性能是分层数值模拟效率和精度的关键。

The delamination often occurs at the interfacial layers , so the performance of the interface element is the key to the efficiency and accuracy of delamination simulation .

故用圆弧元胞来表达试件的加工轨迹时，加工速度与表面质量均有较大的改善。

Therefor , the machining velocity and surface quality of specimens are improved when their machining paths are described by means of arc-cells .

在位势问题、弹性问题、流体问题、电磁场特别是开域场域问题等方面具有广泛的应用前景，故对边界元法的研究一直受到学者和工程人员的重视。

It offers the higher accuracy in the potential problems , the elasticity problems , the hydromechanics , the electromagnetic fields , especially open region problem etc. The study on BEM has been a challenging topic for the scientists , the engineers and technicians .

但是，现有计算方法在实际应用中有一定局限，故提出简化有限元计算方法对于工程计算至关重要。

However , existing calculation methods for PBL shear connector also had limitations in practical applications . It was important to propose a simplified finite element method for engineering calculation .

在这种结构中，极限状态方程是一个含有多随机变量的非线性函数，而且有些随机变量很难用显式表达，故采用随机有限元法进行可靠性分析，给出了系统可靠性指标的敏度表达式；

The limited condition equation is a nonlinear function including many random variables , and some of these variables can not be easily expressed using explicit formula . The reliability analysis is therefore conducted using the stochastic finite element method .