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

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