A new combined transient extraction method coupled with WO3 gas sensors for polluting gases classification

Purpose – The purpose of this paper is to deal with the classification improvement of pollutant using WO3 gases sensors. To evaluate the
discrimination capacity, some experiments were achieved using three gases: ozone, ethanol, acetone and a mixture of ozone and ethanol via four
WO3 sensors.
Design/methodology/approach – To improve the classification accuracy and enhance selectivity, some combined features that were configured
through the principal component analysis were used. First, evaluate the discrimination capacity; some experiments were performed using three
gases: ozone, ethanol, acetone and a mixture of ozone and ethanol, via four WO3 sensors. To this end, three features that are derivate, integral and
the time corresponding to the peak derivate have been extracted from each transient sensor response according to four WO3 gas sensors used. Then
these extracted parameters were used in a combined array.
Findings – The results show that the proposed feature extraction method could extract robust information. The Extreme Learning Machine (ELM)
was used to identify the studied gases. In addition, ELM was compared with the Support Vector Machine (SVM). The experimental results prove the
superiority of the combined features method in our E-nose application, as this method achieves the highest classification rate of 90% using the ELM
and 93.03% using the SVM based on Radial Basis Kernel Function SVM-RBF.
Originality/value – Combined features have been configured from transient response to improve the classification accuracy. The achieved
results show that the proposed feature extraction method could extract robust information. The ELM and SVM were used to identify the
studied gases.