Perhaps you should try some spelling variations:
optimisation algorithm » optimization algorithms, estimation algorithms
passive estimation » pose estimation
modified passive » modified adaptive
df optimisation » _ optimisation, _ optimization, qoe optimization
modified df » modified _, modified adam, modified bi1

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( modified df optimisation algorithm ) OR ( modified passive estimation algorithm ))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( modified df optimisation algorithm ) OR ( modified passive estimation algorithm ))".
• Adding a wildcard symbol may retrieve word variants: (( modified df optimisation algorithm ) OR ( modified passive estimation algorithm ))*.