Perhaps you should try some spelling variations:
"modified multiobjective optimization algorithms" » "modified multiobjective optimisation algorithm", "modified multiobjective estimation algorithms", "modified multiobjective optimized algorithms"
"modified ddrisk estimation algorithm" » "modified risk estimation 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 multiobjective optimization algorithms") OR ("modified ddrisk estimation algorithm"))~.
• Removing quotes may allow a broader search: (( modified multiobjective optimization algorithms ) or ( modified ddrisk estimation algorithm ))~.
• Adding a wildcard symbol may retrieve word variants: (("modified multiobjective optimization algorithms") or ("modified ddrisk estimation algorithm"))*.