Perhaps you should try some spelling variations:
"modified allocation optimization algorithms" » "modified allocation optimisation algorithm", "modified allocation estimation algorithm", "modified allocation optimized algorithms", "modified location optimization algorithms"
"modified sphere estimation algorithms" » "modified sphere estimation algorithm", "modified sphere optimisation algorithm", "modified sphere approximation algorithms", "modified pose estimation algorithms"

Try widening your search to All Fields.

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

• Performing a fuzzy search may retrieve terms with similar spellings: (("modified sphere estimation algorithms") or ("modified allocation optimization algorithms"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("modified sphere estimation algorithms") OR ("modified allocation optimization algorithms")).
• Removing quotes may allow a broader search: (( modified sphere estimation algorithms ) or ( modified allocation optimization algorithms )).
• Adding a wildcard symbol may retrieve word variants: (("modified sphere estimation algorithms") or ("modified allocation optimization algorithms"))*.