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

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

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