Hysteresis and dissipation Hysteretic phenomena are often linked to dissipation. When there is a hysteresis loop, the dissipated energy can usually be computed as the area of the cycle.
For example, in ferromagnetic materials, the relationship between the magnetization and the magnetic field can exhibit a hysteresis loop, corresponding to the microscopic dissipation by Joule effect; in elastic materials, there is a hysteresis in the relation between the constraint and the extension, corresponding to the internal friction.
There are lots of other examples where I do not know exactly the dissipation processes: in all first-order phase transitions (e.g. liquid-gas), in the contact angle, and so on. I feel like hysteretic phenomena cannot appear without dissipation, because hysteresis needs memory as well as the possibility to lose this memory (which is an irreversible process). However, perhaps I miss some other possibility.
So, is hysteresis always linked to dissipation? Is it due to irreversibly? Is there a means to prove that formally?
 A: Bridgman in "The Thermodynamics of Plastic Deformation and
Generalized Entropy", REVIEWS OF MODERN PHYSICS VOLUME 22. NUMBER 1 JANUARY, 1950, is discussing specifically stress-strain hysteretic cycles: 

During the part of the cycle during which heat would be flowing in
  from the outside if there were no hysteresis, less heat flows in than
  otherwise would because the irreversible internal generation of heat
  takes the place of the heat of external origin, so that during this
  part of the process the entropy of the external universe decreases
  less than it otherwise would (that is, there is an equivalent
  algebraic increase). On the other hand, during the part of the process
  during which without hysteresis heat would flow out of the body to the
  surroundings, more heat flows out than otherwise would, the excess
  being generated by the irreversible transformation within the body.
  Again the result is a greater than normal increase of entropy of the
  external universe. On balance, therefore, the total entropy increases
  as it should after every cycle.

Later he generalizes the irreversible entropic description beyond stress-strain cycles, as well, but it seems that Bridgman associates dissipation with hysteresis if not explicitly then at least implicitly everywhere.
A: In the control of certain systems, hysteresis is built into the open loop control logic to prevent the system from oscillating. For example in convertible cars, sometimes there is a fence extending above the windshield to change the airflow. The fence is extended at 35 mph and retracted at 25 mph, for example. If it was extended above 35 and retracted below 35, then it could be continuously going out and back in again when one cruises around 35 mph. If there is dissipation of a certain quantity, then it's at least not immediately obvious.
