说明：  本文根据椭圆弦长的比值相对固定提出了弦长比法, 并运用SOM 神经网络对纽荷尔脐橙进行分级, 取得了一定的效果。
(Based on the ratio of elliptical chord chord made relatively fixed ratio method, and the use of SOM neural network for classification of Newhall navel orange, and achieved some results.)