A single b(egin)-state and a single f(inish)-state suffice to describe the process for a uniform system.

Examples: Work done in compressing a gas in a piston-cylinder device, heat required to raise the temperature of a block of solid, pressure drop in a closed chamber due to cooling, etc. Browse animations in Animations.5.A for more examples.

There are two uniform sub-systems which do not mix and retain their identity in a non-mixing non-uniform system.

Example: In a process in which a hot block of copper comes to thermal equlibrium after being dropped into a tank of water, the sub-systems (A and B) are the copper block and water. To describe the anchor states of the process, four system states -  bA and bB for the b-state, and  fA and fB for the f-state - are required.  The sub-systems, A and B, may exchange energy but not mass at any time during the process. Browse animations in Animations.5.B for more examples.

The daemons in this category are very similar to the mixing (Mixing, Non-Uniform) daemons linked above, except, these allow the valve to be closed before mixing is complete. Beside the composite beginning-state consisting of bA and bB states, the final state is also composite and consists of fA and fB states.

Example: Nitrogen and oxygen in two chambers, when allowed to mix by opening a connecting valve, undergo a semi-mixing process resulting in a composite f-state if the valve is closed before mixing is complete.

Here, too, there are multiple subsystems, requiring two states,  bA and bB, to describe the composite b-state. During the process mass transfer between the sub-systems A and B and energy transfer (heat and work) with the surroundings result in  a single f-state. 

Example: Nitrogen and oxygen in two chambers, when allowed to mix by opening a connecting valve, undergo a mixing process resulting in a single f-state, provided sufficient time is allowed for mixing. Browse animations in Animations.5.C for more examples.