Perhaps you should try some spelling variations:
"modified allocation optimization algorithm" » "modified allocation optimization algorithms", "modified allocation optimisation algorithm", "modified allocation estimation algorithm", "modified location optimization algorithm"
"modified rough approximation algorithms" » "modified rough approximations algorithms", "modified one approximation 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 rough approximation algorithms") OR ("modified allocation optimization algorithm"))~.
• Removing quotes may allow a broader search: (( modified rough approximation algorithms ) or ( modified allocation optimization algorithm ))~.
• Adding a wildcard symbol may retrieve word variants: (("modified rough approximation algorithms") or ("modified allocation optimization algorithm"))*.