Perhaps you should try some spelling variations:
estimation algorithms » estimation algorithm, optimization algorithms, optimisation algorithm
objective estimation » objective optimization, objective allocation
method algorithm » mom algorithm
learning method » learning methods, graining methods, learning emotion
model learning » mobile learning

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 objective estimation algorithms ) OR ( model learning method algorithm ))~.
• Adding a wildcard symbol may retrieve word variants: (( modified objective estimation algorithms ) or ( model learning method algorithm ))*.