  We consider fractional order optimal control problems in which the dynamic
control system involves integer and fractional order derivatives and the
terminal time is free. Necessary conditions for a state/control/terminal-time
triplet to be optimal are obtained. Situations with constraints present at the
end time are also considered. Under appropriate assumptions, it is shown that
the obtained necessary optimality conditions become sufficient. Numerical
methods to solve the problems are presented, and some computational simulations
are discussed in detail.
