Perhaps you should try some spelling variations:
"modified df estimation algorithms" » "modified df estimation algorithm", "modified df optimization algorithms", "modified df optimisation algorithm", "modified _ estimation algorithms", "modified adam estimation algorithms", "modified bi1 estimation algorithms"
"modified parameter optimized algorithms" » "modified parameter optimized algorithm", "modified parameter optimizer algorithms", "modified parameter 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: (("modified df estimation algorithms") OR ("modified parameter optimized algorithms"))~.
• Removing quotes may allow a broader search: (( modified df estimation algorithms ) or ( modified parameter optimized algorithms ))~.
• Adding a wildcard symbol may retrieve word variants: (("modified df estimation algorithms") or ("modified parameter optimized algorithms"))*.