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