Perhaps you should try some spelling variations:
"modified allocation approximation algorithms" » "modified allocation optimization algorithms"
"modified parameter optimisation algorithm" » "modified parameter optimization algorithm", "modified parameter estimation algorithm", "modified parameter optimization algorithms", "modified parameter estimation algorithms"

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