Krzysztof Wilmanski extended the model by introducing a balance equation of porosity.

The balance equation for open systems when modeling wound healing incorporates mass growth due to cell migration and proliferation.

It is sufficient to show satisfies the global balance equations which, quite differently from Jackson networks are non-linear.

Electrovalency is used to help balance equations describing chemical reactions.

If such a solution can be found the resulting equations are usually much easier than directly solving the global balance equations.

In some situations, terms on either side of the global balance equations cancel.

These balance equations were first considered by Peter Whittle.

The theorem is proved by checking that the independent balance equations are satisfied.

We require that each is nonnegative and that the balance equation should hold.

The motivation is to automatically fulfill the relevant balance equations at the infinitesimally small connection point.