It is always difficult to train a two-layer Feedforward Neural Networks (FNN) based on the cumulant match criterion because cumulants are nonlinear implicit functions of the FNN parameters.

• 由于非线性系统输出是其参数的非线性函数,直接利用高阶累积量辨识两层前馈神经网络(FNN)通常是十分困难的。