Perhaps you should try some spelling variations:
optimal preprocessing » optical processing (Expand search), spectral preprocessing (Expand search), data preprocessing (Expand search)
decrease optimal » decrease intimate (Expand search), discrete optimal (Expand search), decrease stigma (Expand search)
decrease not » decrease of (Expand search), decrease akt (Expand search), decrease on (Expand search)
not decrease » to decrease (Expand search), not increase (Expand search), and decrease (Expand search)
in decrease » in decreased (Expand search), on decrease (Expand search), pain decrease (Expand search)
decrease at » decrease akt (Expand search), decrease and (Expand search), decrease of (Expand search)
at decrease » rate decrease (Expand search), that decrease (Expand search), and decrease (Expand search)

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

• Removing quotes may allow a broader search: (( decrease in decrease optimal preprocessing ) OR ( decrease not decrease at decrease ))~.