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UBC Theses and Dissertations

Cross directional response modeling, identification and control of dry weight profile on paper machines Ghofraniha, Jahangir

Abstract

In this thesis, dry weight response modelling, identification and control of the cross directional (CD) profile of a paper sheet is investigated. To date, the available modelling strategies are either very detailed and require computational fluid dynamics techniques or are based on purely input/output identification schemes. The developed model is based on physical principles and is simple enough to be used for CD control purposes. The model is developed as a dispersive wave at the surface of slurry. The combination of surface wave theory and drainage theory results in a closed form model that can simulate different scenarios on the paper machine. Based on the developed model, an identification scheme is developed to identify parameters. The identification scheme makes use of continuous wavelet transform. The identification was applied to simulated data and industrial data. The continuous wavelet transform led to a new CD control algorithm that eliminates the mapping problem which is a draw back of CD control systems due to ill-conditioning and lack of inverse at all times. The control algorithm is demonstrated by application to industrial data.

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