Perhaps you should try some spelling variations:
"modified sphere optimization algorithms" » "modified sphere optimisation algorithm", "modified sphere estimation algorithms", "modified sphere optimized algorithms", "modified stage optimization algorithms", "modified response optimization algorithms"
"modified parameter estimation algorithm" » "modified parameter estimates algorithm", "modified parameter optimization algorithm"

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 sphere optimization algorithms") OR ("modified parameter estimation algorithm"))~.
• Removing quotes may allow a broader search: (( modified sphere optimization algorithms ) or ( modified parameter estimation algorithm ))~.
• Adding a wildcard symbol may retrieve word variants: (("modified sphere optimization algorithms") or ("modified parameter estimation algorithm"))*.