Kinetic, static, phenomenological

Therefore, the simplest procedure to get the stochastic description of the reaction leads to the rather complicated set of equations containing phenomenological parameters / (equation (2.2.17)) with non-transparent physical meaning. Fluctuations are still considered as a result of the external perturbation. An advantage of this approach is a useful analogy of reaction kinetics and the physics of equilibrium critical phenomena. As is well known, because of their nonlinearity, equations (2.1.40) reveal non-equilibrium bifurcations [78, 113]. A description of diffusion-controlled reactions in terms of continuous Markov process - equation (2.2.15) - makes our problem very similar to the static and dynamic theory of critical phenomena [63, 87]. When approaching the bifurcation points, the systems with reactions become very sensitive to the environment fluctuations, which can even produce new nonequilibrium transitions [18, 67, 68, 90, 108]. The language developed in the physics of critical phenomena can be directly applied to the processes in spatially extended systems. 

In the further elaboration a general phenomenological framework for wetting can be developed. Because of its thermodynamic nature, this framework is macroscopic and static it refers to equilibrium or to reversible processes. So, the kinetics of wetting cannot be analyzed in this way and only one contact angle, the equilibrium angle, can be considered. It remains an issue how this thermodynamic contact angle relates to the one that is physically measurable. Another typical feature is that interfaces are always taken to be at equilibrium with the adjacent... 

Kinetic friction differs phenomenologically from static friction in that rather than being in a state of impending or beginning motion, the sliding body is moving overtly with respect to the stationary body. Me write the following expression for the coefficient of kinetic friction... 

N (7-6) where is the negative of the tangential force required to keep the slider moving at constant velocity. Equation 7-6 is a formal statement defining the coefficient of kinetic friction and also the expression of a phenomenological fact. Its counterpart for the coefficient of static friction is... 

In terms of the behavior that actually would be observed with a simple apparatus of the kind described above, there is a direct and obvious phenomenological difference between static and kinetic friction. Close inquiry has revealed that in addition to theoretical considerations, the experimental methods and the instrumentation used to study and measure friction are an important aspect of the behavioristic manifestation of this difference. Therefore an examination of some-7 of the more refined methods for the investigation of friction is in order. 

Since 40 s of last century, catal3dic scientists have combined the results obtained on catalysts from the study of reaction kinetics with the characterization or measurement at static state conditions by XRD, adsorption, thermal analysis, and IR etc. Although now the correlations have not been limited to bulk catalysts, and moreover can be extended to their surface features, this phenomenological method can only provide partial information about reaction mechanism. 

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