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