Target theory conditions

Occasionally, one could have read about the failures of the Theory of Similarity or of its limits. However, this criticism has arisen when, due to some physical reasons, a complete similarity could not be achieved (see e.g. remarks of Damkohler [113] on p. 183) or the scale-up criterion could not have been worked out with certainty because the measuring conditions did not allow it (false model scale, wanted sensitivity of the target quantity, non-availability of the model material system, ignorance about relevant physical properties, such as in foams and sludges, etc.). 

Similar to the minimum-work concept in thermodynamics, control theory should provide achievable targets of performance and should do so under practical conditions, e.g., when the manipulated variables are constrained and when the model used for assessing the performance is only an approximate representation of the real system. The targets should be independent of controller complexity. They should allow the designer to assess the merits of simple, empirical control strategies and to judge different process designs in terms of their operability. 

It has not escaped our attention that if the present theory is correct, then the transition structures of wide classes of reactions, among them enzyme catalyzed ones, are a necessary and sufficient condition for the given mechanism to exist. The universality of the electronic wave function imposes a certain invariance to the stationary structure. Thus, in so far as molecular evolution is concerned, the enzymes have a fairly invariant target towards which evolve, namely, to bind the substrates in a geometry as similar as possible to the geometry of the transition structure in vacuum [52,53]. This may be surprising, but if warranted by future experience, would provide sound basis to understand the nature of catalysts in general [54],... 

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