Water current problems including relative steady and rather fluctuant free surface were simulating numerically.

对含有相对稳定的和起伏较大的自由水面的水流问题进行了数值模拟。

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This paper discussed concept, challenges and current problems of final surface finishing process for PCB. Trend of being lead-free for electronic products was proposed.

对印制板表面终饰工艺的概念、面临的挑战及现存的问题进行了阐述，并提出了电子产品的无铅化趋势。

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