Perhaps you should try some spelling variations:
"modified multiobjective optimizer algorithms" » "modified multiobjective optimization algorithms", "modified multiobjective optimized algorithms", "modified multiobjective optimized algorithm"
"modified average approximation algorithms" » "modified coverage approximation 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 average approximation algorithms") or ("modified multiobjective optimizer algorithms"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("modified average approximation algorithms") OR ("modified multiobjective optimizer algorithms")).
• Removing quotes may allow a broader search: (( modified average approximation algorithms ) or ( modified multiobjective optimizer algorithms )).
• Adding a wildcard symbol may retrieve word variants: (("modified average approximation algorithms") or ("modified multiobjective optimizer algorithms"))*.