Perhaps you should try some spelling variations:
"modified objective estimation algorithms" » "modified objective estimation algorithm", "modified objective optimization algorithms", "modified objective optimisation algorithm", "modified objective allocation algorithms"
"active learning method algorithm" » "active learning mom algorithm", "machine learning method algorithm", "active learning methods algorithm", "active graining methods algorithm", "active learning emotion algorithm"

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: (("modified objective estimation algorithms") or ("active learning method algorithm"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("modified objective estimation algorithms") OR ("active learning method algorithm")).
• Removing quotes may allow a broader search: (( modified objective estimation algorithms ) or ( active learning method algorithm )).
• Adding a wildcard symbol may retrieve word variants: (("modified objective estimation algorithms") or ("active learning method algorithm"))*.