2.3.1.1. Time domain features. Features extracted from time domain can
intuitively represent signal characteristics. Maximum value (MV) and
average value (AV) are two frequently-used time domain features for
E-nose signal analysis. MV represents the maximum signal strength
which can reflect the dynamic characteristics of signals. AV represents
the average signal strength which can reflect the overall level of signal
strength.
MV denotes the maximum point of the absolute values of sensor
response within 120 s. The MV of the i-th sensor is defined as follows: