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
active learning » machine learning
learning method » learning methods, graining methods, learning emotion

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

• The words AND, OR and NOT may confuse the search; try adding quotes: "(( active learning method algorithm ) OR ( modified objective estimation algorithms ))~".
• Adding a wildcard symbol may retrieve word variants: (( active learning method algorithm ) OR ( modified objective estimation algorithms ))*.