The figure below shows a direct current electrical
network. A mathematical programming model can be used to find
the current flows I_{1}, I_{2} and I_{3}.
The current flows are the variables of the model.
a. The model requires the single constraint:
.
Explain the purpose of this constraint.
b. Write the nonlinear objective function that when minimized
will determine the values of the currents.
c. When the model is solved with a procedure such as the
Solver in Excel, is one assured of global optimum? Justify your
conclusions based on the constraint of part a and the objective
of part b.
