Perhaps you should try some spelling variations:
"defined network optimization algorithms" » "defined network optimisation algorithm", "defined network estimation algorithms", "defined network estimation algorithm", "designed network optimization algorithms"
"modified adaptive approximation algorithms" » "modified time approximation algorithms", "modified passive approximation 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: (("defined network optimization algorithms") OR ("modified adaptive approximation algorithms"))~.
• Removing quotes may allow a broader search: (( defined network optimization algorithms ) or ( modified adaptive approximation algorithms ))~.
• Adding a wildcard symbol may retrieve word variants: (("defined network optimization algorithms") or ("modified adaptive approximation algorithms"))*.