How Do I Get Out of Contradiction Mode?

Once you enter contradiction mode, CyclePad will not let you proceed until you clear one of the assumptions underlaying the contradiction. To clear the assumption you must retract one of the assumptions in the report window. Once you have done so, click on OK and CyclePad will check to see that all contradictions (there may be more than one) have been resolved. You can use the facilities of the explanation system to figure out which of your assumptions to retract.

If you have assumed a numerical value for a substance that is outside the range of CyclePad’s tables, the contradiction dialog will show you where your value is with respect to the approximate range of the table:

This is probably the easiest contradiction to recover from, because it was very likely provoked by the most recent value you entered. In the example shown, a temperature of 2500 °C is above our table range, whose boundaries are shown on the plot. In any case, it will be relatively easy to determine which value is out of range, and retract that value.

If you do not see this dialog, then the contradiction is not due to a value falling outside of CyclePad’s tables.

Depending on the particular problem, there are several ways to proceed. You may find it helpful to work backwards, asking why the contradictory facts were believed and working back to the assumptions. Or you may find it helpful to work forward from your assumptions, moving through their consequences to see where things went astray. Often a combination of working forwards and backwards provides the best results.

In the above example, asking "Why is V(S1) > V G(Tsat)(S1) False?" will pop up an explanation windowInvestigating_a_Cycle_via_the_Explanation_System telling you that S1 is not a gas. If we continue along this line of questions, we will find that S1 is not a gas because we have assumed that S1 is saturated. Exploring in this manner, eventually we will learn how one of our assumptions has led to a contradiction.

All contradictory statements and assumptions are hypertext items that can be explored and manipulated by clicking on them with the mouse to get a menu of appropriate commands.

Once an assumption underlaying a contradiction has been retracted, CyclePad removes the contradiction window and returns you to continue your analysis.