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