Perhaps you should try some spelling variations:
by preprocessing » the preprocessing (Expand search), and preprocessing (Expand search), by processing (Expand search)
may decreased » may decrease (Expand search), has decreased (Expand search), by decreased (Expand search)
decrease may » decrease at (Expand search), decrease by (Expand search), decrease human (Expand search)
decreased by » decreased in (Expand search), increased by (Expand search), decreased il (Expand search)
decrease of » decrease in (Expand search)
of decrease » or decrease (Expand search), not decrease (Expand search), to decrease (Expand search)

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

• The words AND, OR and NOT may confuse the search; try adding quotes: "(( decrease may decreased by preprocessing ) OR ( decrease of decrease OR decrease ))~".
• Adding a wildcard symbol may retrieve word variants: (( decrease may decreased by preprocessing ) OR ( decrease of decrease OR decrease ))*.