“…This method is mainly focused on the NOx emission of the exhaust gas. In this regard, numerous algorithms, including statistical regression (Li et al, 2004;Chunlin Wang et al, 2018), support vector machine (Wei et al, 2013;Zhou et al, 2012;Ahmed et al, 2015;Lv et al, 2013), artificial neural network (ANN) (Chu et al, 2003;Ilamathi et al, 2013;Preeti and Sharad, 2013;Jacob and Tuttll, 2019), and deep learning (Li and Hu, 2020;Yang et al, 2020;Tan et al, 2019;Xie et al, 2020;Kang et al, 2017;Wang et al, 2017) are often used to predict the NOx concentration. Although remarkable achievements have been obtained in this area, the time complexity of support vector machines increases exponentially as the sample size increases.…”