Perhaps you should try some spelling variations:
estimation algorithms » estimation algorithm, optimization algorithms, optimisation algorithm
solution algorithm » evolution algorithm, convolution algorithms, evolutionary algorithm
modified positive » modified passive, modified adaptive
positive solution » positive solutions
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 positive solution algorithm ) OR ( modified df estimation algorithms ))~.
• Adding a wildcard symbol may retrieve word variants: (( modified positive solution algorithm ) or ( modified df estimation algorithms ))*.