DELTA X-A NEW CONTROL SYSTEM
You may have the impression that the name delta-x control system means a completely new system with only a delta-x control. Therefore, I have to start by explaining that a contemporary Dutch glasshouse climate controller includes many user possibilities in a program built into the system. One of the possibilities is to control on the basis of the Δ x or, which amounts to the same thing, the moisture deficit of the glasshouse air. If we have had some success with it, this was also because of the other possibilities which we shall discuss, after an explanation of the concept of moisture deficit.
Heijna, B.J. (1975). DELTA X-A NEW CONTROL SYSTEM. Acta Hortic. 46, 13-20