Perhaps you should try some spelling variations:
"modified orca approximation algorithm" » "modified orca approximation algorithms", "modified one approximation algorithm", "modified _ approximation algorithm", "modified time approximation algorithm"
"modified objective optimization algorithm" » "modified multiobjective optimization algorithm", "modified objective optimization algorithms", "modified objective optimisation algorithm", "modified objective estimation algorithm"

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 objective optimization algorithm"))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"modified orca approximation algorithm\") OR (\"modified objective optimization algorithm\"))*".
• Removing quotes may allow a broader search: (( modified orca approximation algorithm ) OR ( modified objective optimization algorithm ))*.