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

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: (( sphere optimisation algorithm ) OR ( ((qoe optimisation) OR (qoe optimization)) algorithm ))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( sphere optimisation algorithm ) or ( ((qoe optimisation) OR (qoe optimization)) algorithm ))~".
• Adding a wildcard symbol may retrieve word variants: (( sphere optimisation algorithm ) or ( ((qoe optimisation) OR (qoe optimization)) algorithm ))*.