The formulas of the spectral element method in polar coordinate are induced and described in detail. Spectral element method is a high-order weighted residualtechnique.
详细推导了在极坐标系下的谱元方法的具体计算公式，求解了极坐标系下的简单椭圆型二阶偏微分方程；
2
The second technique involved using braided solder wick and a soldering iron with a blade tip to remove residual solder from the PCB pad.
第二个技术工艺涉及到使用网状焊料芯吸法及有刀片尖的焊接烙铁来除去PC B焊盘上的残余焊料。
3
It can be concluded that the local high temperature can be reduced effectively using the technique of discontinuous welding and smaller residual stresses are obtained.