Effect of Synchronization on Bilinear Batch Process Modeling

There is a widespread assumption that batch synchronization is only required if the batch trajectories have different duration. This paper is devoted to demonstrate that synchronization is a critical and necessary preliminary step to bilinear batch process modeling, no matter whether batch trajectories have equal length or not. Another practical assumption is that all batches need the same synchronization method to be aligned. Two different synchronization approaches are compared in terms of synchronization quality: the Multisynchro approach that takes into account the type of asynchronism and the method based on linearly expanding and/or compressing pieces of variables trajectories (the TLEC method), implemented in commercial software. The consequences of inappropriately synchronizing batch data with multiple asynchronisms in process monitoring are investigated. For this study, the observationwise unfolding-T scores batchwise unfolding (OWU-TBWU) approach, which integrates the TLEC method for batch synchronization, is used for process modeling. Data from realistic simulations of a fermentation process of the Saccharomyces cerevisiae cultivation with five different types of asynchronism are used for illustration.