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