Optimal processes in open controllable macrosystems

General features are considered and studies are made of stationary modes and optimal behavior of active (control) subsystems in open macrosystems. An expression that reaches a minimum in the stationary state differing little from the equilibrium state is derived. Conditions are defined concretely for thermodynamic and economic systems and, as a consequence, solutions are found of the problems for a maximum power of a heat engine, minimum expenses of energy in irreversible separation processes, a limit capacity of thermal separation, and a limit rate of capital recovery in microeconomic systems.