“…To solve this issue, a nonlinear PLS method, called kernel partial least squares (KPLS), was proposed by Rosipal and Trejo (Rosipal and Trejo, 2002). The original datasets are nonlinearly transformed into a feature space of arbitrary dimensionality via nonlinear mapping, and then a linear model is created in the feature space (Zhang et al, 2012;Zhang and Hu, 2011). Because it's easy to understand and operate, KPLS has been widely used in many fields, such as pattern recognition (Qu et al, 2010), signal processing (Helander et al, 2012), fault diagnosis (Zhang et al, 2010b), and so on.…”