The concept of "Aiki" is not limited to our Aikido techniques alone.
"Aiki" is present in any technique that allows a person to experience "Ju" with an attack.
For example: If your opponent pushes you, & you use his forward force/momentum (together with a little of your own force) to break his balance, you are actually using "Aiki" to experience "Ju" for yourself.
If a person truly wishes to experience "Ju" in his techniques, he has to use "Aiki".
"Ju" & "Aiki" are very closely inter-related. Their relationship is that of a "Cause&Effect" nature.
The use of "Aiki" allows you to experience "Ju".
Ahhh, no. I don't have to use "aiki" to experience "ju". Using your example, I am using the "ju" principle from beginning to end.
If that is what "aiki" is (putting that little extra force behind my technique) then the discussions on this board for the past 8 years have been a waste of time. You just defined it.