Between-phase transition analysis for phase-based quality prediction

In this paper, the quality-concerned between-phase transition patterns are analyzed for quality prediction and interpretation in multiphase batch processes. From the between-phase viewpoint, the quality-related phase behaviors are decomposed and two subspaces are separated. In common subspace, the underlying quality-relevant variation stays invariable compared with its neighboring phases, showing the common contribution to quality. The other part changes with the alternation of phases and has the different influences on quality interpretation, termed specific subspace here. Based on subspace separation, quality-related process information is captured across phases and between-phase transition regions are distinguished from steady phases. Steady phase and transition models are developed respectively for online quality prediction. The proposed method gives an interesting insight into the phase behaviors and between-phase transitions for quality prediction. The feasibility and performance of the proposed method are illustrated with a typical multiphase batch process.