求解开域电磁场问题的区域映射有限元法

为了求解开域电磁场问题,提出一种区域映射有限元方法。该方法把待求解的无限大区域划分为内部有限区域和外部无限区域。对内部区域,形成传统的有限元方程;对外部区域,引入几何中的Kelvin变换,对变换后的场域形成另一个有限元方程。内外区域的方程在公共边界上耦合。结果表明,该方法使用1/9甚至更少的单元即可达到传统有限元法的精度。与传统有限元法相比,该方法大量减少生成的网格单元数、计算所需的内存和时间。已在二维和三维开域问题计算中实现了该方法。     

Combination Approach of FEM and Circuit System in IR Drop Analysis and Its Applications

A method was developed to solve the combined system of the current field and the circuit. The ＂super-node＂ was used to transform the matrix for conventional nodal analyses of a circuit system from non-positive definite to positive definite. Then, a positive definite matrix for the overall system was obtained by combining the matrix from the circuit nodal analysis method and the matrix resulted from finite element method （FEM） formulation to solve the FEM fields. This approach has been successfully applied to simulate the electrical potential and current distributions on each metal layer of printed circuit boards （PCBs） and integrated circuit （IC） packages for a given power supply. The simulation results can then be used to analyze the properties of the PCBs and IC packages such as the port resistances and IR drops. The results can also be used to optimize PCB and IC package designs, such as by adjusting the power/ground distribution networks.     

U型立绒立体周期结构频率选择织物的性能

 采用立绒织造方式,以银纤维纱线作为导电结构单元材料,制备了基于U型立绒单元的立体周期结构频率选择纺织品。与具有U型底部长度同样尺寸的平面偶极子周期结构织物相比,U型立绒在偶极子两个端点沿Z轴向空间延伸。U型立绒立体周期结构织物在2~18 GHz内具有双频点谐振效应;谐振频率随着U型底部连通长度增加向低频移动,在同样的底部长度下,U型个数不影响谐振频率;银纤维构成的结构单元织物比不锈钢纤维纱线具有更加尖锐的谐振峰。进一步实现了基于银纤维纱线的、簇集U型立绒构成的十字体结构单元频率选择织物,表明立体周期结构织物具有丰富的灵活可设计性。