Perhaps you should try some spelling variations:
"modified objective optimization algorithm" » "modified multiobjective optimization algorithm", "modified objective optimization algorithms", "modified objective optimisation algorithm", "modified objective estimation 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.

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