The results shows that Beggs - brill method is the best, flow pattern method is the second and Dans-Nos method is the third, which can be of reference to designers.

• 结果表明,在这些方法中,贝格斯-布里尔方法最佳,其次是流动型态法,再次是丹斯-若斯方法。以上结果可供设计工作者参考。