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

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 passive estimation algorithm") OR ("modified allocation estimation algorithms"))~.
• Removing quotes may allow a broader search: (( modified passive estimation algorithm ) or ( modified allocation estimation algorithms ))~.
• Adding a wildcard symbol may retrieve word variants: (("modified passive estimation algorithm") or ("modified allocation estimation algorithms"))*.