Perhaps you should try some spelling variations:
optimization algorithm » optimization algorithms, optimisation algorithm, estimation algorithms
learning estimation » learning emotion, lighting estimation
mobile learning » machine learning
df optimization » _ optimization, qoe optimization, _ optimisation
modified df » modified _, modified adam, modified bi1

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( mobile learning estimation algorithm ) or ( modified df optimization algorithm ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( mobile learning estimation algorithm ) OR ( modified df optimization algorithm )).
• Adding a wildcard symbol may retrieve word variants: (( mobile learning estimation algorithm ) or ( modified df optimization algorithm ))*.