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一、引言众所周知,我国在进行水文频率计算时,广泛应用了适线法推求P-Ⅲ型曲线的参数。适线法的缺点是:(1)P-Ⅲ型曲线有三个参数,但在适线时,实际调试多限于偏态系数Cs,而直接把矩法求得的样本均值X,离散系数Cv作为总体的估计值,这便影响了曲线的弹性和适线精度;(2)须手工点绘曲线,目估适线,费时,精度不易控制,任意性较大。最近,探求应用非线性规划的单纯形法计算曲线参数,经多次验证,它在避免适线法缺陷并取得优化成果方面有可取之处。本文将此法作简要介绍,以期得到进一步的检验。
I. INTRODUCTION It is well known that when calculating hydrological frequencies in our country, the parameters of P-Ⅲ type curve are widely used in our country. The shortcomings of the line method is: (1) P-Ⅲ type curve has three parameters, but in the line, the actual debugging more limited to the skew coefficient Cs, and the moment method directly to obtain the sample mean X, discrete coefficient Cv as The overall estimate, which will affect the flexibility of the curve and fitness accuracy; (2) the curve must be drawn by hand point of sight, assessment of fitness line, time-consuming, accuracy is not easy to control, arbitrariness larger. Recently, the simplex method to calculate the curve parameters using nonlinear programming has proved its merits in avoiding the defects of the adaptive method and obtaining the optimization results after many verifications. This article gives a brief introduction of this method, with a view to further testing.