On a non-linear law of the irreversible phenomena with stationary constraints

In 1954, I. Prigogine and the present author established that the time derivative of the entropy production, for constant values of the fluxes, is always negative or zero when the boundary conditions of the system are stationary. However, mechanical equlibrium was postulated and it follows that the dissipative forces were not taken into consideration but only the other cases of irreversibility (chemical reactions, heat and diffusion). In this work the above limitation is eliminated. The system, however, is assumed to be in mechanical steady flow during the whole process.