Perhaps you should try some spelling variations:
approximation algorithm » approximation algorithms
estimation algorithms » estimation algorithm, optimization algorithms, optimisation algorithm
orca approximation » one approximation, _ approximation, time approximation
passive estimation » pose estimation
modified passive » modified adaptive

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

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