The paper expatiated how to confirm and calculate these parameters such as durable years and discount rate of technical asset . there is n ' t external in profit calculation in tradition , back propagation training can avoid 传统预测收益有相当的主观因素，而bp神经算法在对历史数据训练的基础上直接计算出预期收益，有摒弃主观预测的优势。
