Perhaps you should try some spelling variations:
optimisation algorithm » optimization algorithms, estimation algorithm, estimation algorithms
sphere optimisation » sphere estimation
over optimization » _ optimization, game optimization
qoe optimization » game optimization, _ optimization, stage optimization

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( ((over optimization) OR (qoe optimization)) algorithms ) or ( sphere optimisation algorithm ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( ((over optimization) OR (qoe optimization)) algorithms ) OR ( sphere optimisation algorithm ))*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( ((over optimization) OR (qoe optimization)) algorithms ) or ( sphere optimisation algorithm ))*".