Aiming at the problem that in the process of preparing fuel ethanol by straw fermentation

real-time online detection of ethanol concentration is difficult

and the lag of off-line detection is large

a neural network soft measurement model considering time lag is designed.Firstly

some process variables are analyzed and processed.Secondly

the time-delay parameter T is introduced to reduce the hysteresis effect caused by offline measurement.Finally

back propagation（BP） neural network is used to establish the soft-measurement model.The simulation results show that after adding the time-delay parameter

the auxiliary variable has a higher correlation with the key variable

which can realize the real-time soft measurement of ethanol concentration more accurately.