Perhaps you should try some spelling variations:
"materials optimization" » "material optimization", "criteria optimization", "models optimization"
"automatic estimation" » "automatic optimization", "automatic extraction", "automatic evaluation"
"mathematical optimization" » "mathematics optimization"

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: (("mathematical optimization") OR ((("materials optimization") OR ("automatic estimation")))).
• Removing quotes may allow a broader search: (( mathematical optimization ) or ((( materials optimization ) or ( automatic estimation )))).
• Adding a wildcard symbol may retrieve word variants: (("mathematical optimization") or ((("materials optimization") or ("automatic estimation"))))*.