Perhaps you should try some spelling variations:
"modified allocation optimization algorithm" » "modified allocation optimization algorithms", "modified allocation optimisation algorithm", "modified allocation estimation algorithm", "modified location optimization algorithm"
"defined network approximation algorithms" » "designed network approximation algorithms"

Try widening your search to All Fields.

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

• Performing a fuzzy search may retrieve terms with similar spellings: (("defined network approximation algorithms") or ("modified allocation optimization algorithm"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("defined network approximation algorithms") OR ("modified allocation optimization algorithm")).
• Removing quotes may allow a broader search: (( defined network approximation algorithms ) or ( modified allocation optimization algorithm )).
• Adding a wildcard symbol may retrieve word variants: (("defined network approximation algorithms") or ("modified allocation optimization algorithm"))*.