Transparency, relationship nonlinearity

Harper has extensively investigated the role of the ir-conjugation bridge segment in effecting the nonlinearity-transparency relationship. In Fig. 2, data are shown for two different bridge systems 4-(donor)cinnamylidene and l-(4-donor)-phenylene-2-thien-5-ylidene. Acceptors have been varied to span the entire visible optical spectrum. 

Applications of Hammerstein-Wiener model are in wide areas, for example we can mention modelling electromechanical system and radio frequency components, audio and speech processing and predictive control of chemical processes. These models have a useful block representation, transparent relationship to linear systems, and are easier to implement than heavy-duty nonlinear. So, they are very usefiil. 

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