Perhaps you should try some spelling variations:
optimal controller » optimal control (Expand search), logical controller (Expand search), digital controller (Expand search)
decrease decrease » decrease release (Expand search), decreases disease (Expand search), disease decreases (Expand search)
discrete optimal » discrete time (Expand search)
decrease after » disease after (Expand search)
decrease rate » decreased rate (Expand search), decreases rate (Expand search), decrease at (Expand search)
rate discrete » are discrete (Expand search), at discrete (Expand search), vote discrete (Expand search)
decrease and » decreases and (Expand search), decrease in (Expand search), decrease of (Expand search)
and decrease » and decreases (Expand search), and decreased (Expand search), and increase (Expand search)

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: (( decrease rate discrete optimal controller ) OR ( decrease AND decrease decrease after ))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( decrease rate discrete optimal controller ) OR ( decrease and decrease decrease after ))~".
• Adding a wildcard symbol may retrieve word variants: (( decrease rate discrete optimal controller ) OR ( decrease and decrease decrease after ))*.