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 sphere estimation algorithms" » "modified sphere estimation algorithm", "modified sphere optimisation algorithm", "modified sphere approximation algorithms", "modified pose 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 sphere estimation algorithms") OR ("modified parameter optimization algorithms"))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"modified sphere estimation algorithms\") OR (\"modified parameter optimization algorithms\"))".
• Removing quotes may allow a broader search: (( modified sphere estimation algorithms ) OR ( modified parameter optimization algorithms )).
• Adding a wildcard symbol may retrieve word variants: (("modified sphere estimation algorithms") OR ("modified parameter optimization algorithms"))*.