Perhaps you should try some spelling variations:
"modified objective estimation algorithms" » "modified objective optimization algorithms", "modified objective optimisation algorithm", "modified objective approximation algorithms", "modified objective allocation algorithms"
"active learning estimation algorithm" » "active learning emotion algorithm", "active lighting estimation algorithm", "machine learning estimation algorithm"

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: (("active learning estimation algorithm") OR ("modified objective estimation algorithms"))~.
• Removing quotes may allow a broader search: (( active learning estimation algorithm ) or ( modified objective estimation algorithms ))~.
• Adding a wildcard symbol may retrieve word variants: (("active learning estimation algorithm") or ("modified objective estimation algorithms"))*.