Perhaps you should try some spelling variations:
"modified passive estimation algorithms" » "modified passive optimization algorithms", "modified passive optimisation algorithm", "modified passive approximation algorithms", "modified pose estimation algorithms", "modified adaptive estimation algorithms"
"modified parameters estimation algorithm" » "modified parameter estimation algorithm", "modified parameter estimates algorithm", "modified parameter optimization 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 algorithms") OR ("modified parameters estimation algorithm"))~.
• Removing quotes may allow a broader search: (( modified passive estimation algorithms ) or ( modified parameters estimation algorithm ))~.
• Adding a wildcard symbol may retrieve word variants: (("modified passive estimation algorithms") or ("modified parameters estimation algorithm"))*.