Perhaps you should try some spelling variations:
"modified objective estimation algorithms" » "modified objective estimation algorithm", "modified objective optimization algorithms", "modified objective optimisation algorithm", "modified objective allocation algorithms"
"modified invasive approximation algorithms" » "modified passive approximation algorithms"

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: "((\"modified invasive approximation algorithms\") OR (\"modified objective estimation algorithms\"))~".
• Removing quotes may allow a broader search: (( modified invasive approximation algorithms ) OR ( modified objective estimation algorithms ))~.
• Adding a wildcard symbol may retrieve word variants: (("modified invasive approximation algorithms") OR ("modified objective estimation algorithms"))*.