Perhaps you should try some spelling variations:
optimization algorithms » optimisation algorithm, estimation algorithm, optimized algorithms
objective optimization » multiobjective optimization
estimation algorithms » estimation algorithm, optimisation algorithm, approximation algorithms
df estimation » _ estimation
modified df » modified _, modified adam, modified bi1

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 objective optimization algorithms ))~.
• Adding a wildcard symbol may retrieve word variants: (( modified df estimation algorithms ) or ( modified objective optimization algorithms ))*.