Bubble population in a fluidized bed

In the present stochastic model of the bubble population in a fluidized bed, the number of bubbles of any given size is a random variable which can be characterized by its mean value, its co-variance with the other random variables, and the time correlation functions. The later are functions which describe the dynamic character of the fluctuations of the random variable. It should be noted that, unlike a deterministic variable, at steady state the random variable will not reach a fixed value but will continue... 

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