Constant-phase-element formula

Therefore, although the Hessian is very sparse and its nonzero elements are known, it might be better, in the initial phase, to calculate the product Gp using the formula (4.18) and a limited number of iterations to estimate d. In this case, the Hessian is calculated only in the final phase and is kept constant for several iterations together with the possible preconditioner matrix M. 

A jU is the difference between the chemical potentials of A at the two phase boundaries of the reaction product, and A is the standard free energy of formation of A B from the elements- This formula applies as long as local thermodynamic equilibrium is maintained, and it can easily be derived from the equilibrium condition for the reaction A - - mi = A B ,. Integration of eq. (7-28) yields the parabolic reaction rate law in the form = 2 let, and the parabolic (practical) reaction rate constant is given by ... 

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