The limiting values of    are given as follows:

. For this value, Equation (7.290) becomes

(7.292)

This gives,

(7.293)

It is easy to see that this is a series connected model which gives the lower bound of a composite modulus.

. For this case, we get

(7.294)

Thus, Equation (7.290) becomes

(7.295)

This is the parallel connected model. This gives the upper bound of a composite modulus. Thus,  is regarded as a reinforcement measure. This factor covers all possible range of the composite moduli as it varies from zero to infinity. Once this factor is known, the composite moduli are determined from the generalized formula.