Robert K. Niven

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A reduced-order modelling (ROM) strategy is crucial to achieve model-based control in a wide class of flow configurations. In turbulence, ROMs are mostly derived by Galerkin projection of first-principles equations onto the proper orthogonal decomposition (POD) modes. These POD ROMs are known to be relatively fragile when used for control design. To(More)
We examine the combinatorial or probabilistic definition (" Boltzmann's principle ") of the en-tropy or cross-entropy function H ∝ ln W or D ∝ − ln P, where W is the statistical weight and P the probability of a given realization of a system. Extremisation of H or D, subject to any constraints, thus selects the " most probable " (MaxProb) realization. If(More)
1 Abstract This study critically analyses the information-theoretic, axiomatic and combinatorial philosophical bases of the entropy and cross-entropy concepts. The combinatorial basis is shown to be the most fundamental (most primitive) of these three bases, since it gives (i) a derivation for the Kullback-Leibler cross-entropy and Shannon entropy(More)
This study examines a new formulation of non-equilibrium thermodynamics, which gives a conditional derivation of the " maximum entropy production " (MEP) principle for flow and/or chemical reaction systems at steady state. The analysis uses a dimen-sionless potential function φ st for non-equilibrium systems, analogous to the free energy concept of(More)
The combinatorial basis of entropy, given by Boltzmann, can be written H = N −1 ln W, where H is the dimensionless entropy, N is the number of entities and W is number of ways in which a given realization of a system can occur (its statistical weight). This can be broadened to give generalized combinatorial (or probabilistic) definitions of entropy and(More)