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 notion optimization algorithms" » "modified notion optimisation algorithm", "modified notion estimation algorithms", "modified notion estimation algorithm", "modified network optimization algorithms", "modified policy optimization algorithms", "modified allocation optimization algorithms"

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

• If you are trying to use Boolean operators, they must be ALL CAPS: (("modified orca approximation algorithm") OR ("modified notion optimization algorithms"))~.
• Removing quotes may allow a broader search: (( modified orca approximation algorithm ) or ( modified notion optimization algorithms ))~.
• Adding a wildcard symbol may retrieve word variants: (("modified orca approximation algorithm") or ("modified notion optimization algorithms"))*.