Perhaps you should try some spelling variations:
"policy estimation algorithms" » "policy estimation algorithm", "policy optimization algorithms", "policy optimisation algorithm", "pose estimation algorithms", "motion estimation algorithms"
"3d simulation algorithm" » "3d estimation algorithm", "3d solution algorithm", "3d optimisation algorithm", "a simulation algorithm", "mri simulation algorithm", "via simulation algorithm"
"_ simulation algorithm" » "_ estimation algorithm", "_ solution algorithm", "_ optimisation algorithm"

Try widening your search to All Fields.

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

• Performing a fuzzy search may retrieve terms with similar spellings: (("policy estimation algorithms") or ((("3d simulation algorithm") OR ("_ simulation algorithm"))))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("policy estimation algorithms") OR ((("3d simulation algorithm") OR ("_ simulation algorithm")))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"policy estimation algorithms\") or (((\"3d simulation algorithm\") OR (\"_ simulation algorithm\"))))".
• Removing quotes may allow a broader search: (( policy estimation algorithms ) or ((( 3d simulation algorithm ) OR ( _ simulation algorithm )))).
• Adding a wildcard symbol may retrieve word variants: (("policy estimation algorithms") or ((("3d simulation algorithm") OR ("_ simulation algorithm"))))*.