In situ imaging of paste extrusion using electrical impedance tomography

A case study is presented where electrical impedance tomography is used to image paste during extrusion. This indicates regions of high moisture at the wall of the barrel permitting slip and so making extrusion more efficient. Multi-step Gauss–Newton image reconstruction methods are used. Techniques include (i) axi-symmetric smoothing that is coupled with ultrasound measurement to provide discretization information, (ii) full impedance imaging and (iii) full three-dimensional field modelling. These provide clear images of the paste that can be used to gauge extrudability of a paste formulation.

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