“…where the state variable x = (x 1 , x 2 ) ⊤ ∈ R 2 is the vector of the entropies x 1 and x 2 of subsystem 1 and 2, U (x 1 , x 2 ) = U 1 (x 1 ) + U 2 (x 2 ) is the internal energy of the overall system composed of the addition of the internal energies of each subsystem, the gradient of the total internal energy ∂U ∂xi = T i (x i ) being the temperatures of each compartment with T (x i ) = T 0 exp xi ci , where T 0 and c i are constants (Couenne et al, 2006), λ, λ e > 0 denote Fourier's heat conduction coefficients of the internal and external walls respectively and the controlled input u(t) is the temperature of the external heat source. The Thermodynamic Phase Space is R 5 ∋ (x 0 , x 1 , x 2 , p 1 , p 2 ) ⊤ and its elements correspond respectively to the total internal energy, the entropies and the temperatures.…”