Signed digraphs

H. Vedam and V. Venkatasubramanian. Signed digraph based multiple fault diagnosis. Computers and Chemical Engineering, 21 655-660, 1997. 

Diagnostic methods for chemical processes are broadly classified as ones that use process model, and ones that rely on process history data. And they are classified as qualitative ones and quantitative ones, respectively (Venkatasubramanian, 2000). This study suggests a new hybrid method based on signed digraph (SDG) in qualitative model-based methods, and partial least squares (or projection to latent structures, PLS) in quantitative history data-based methods. 

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