Perhaps you should try some spelling variations:
"mathematics optimization" » "mathematical optimization", "materials optimization"
"material optimization" » "numerical optimization", "criteria optimization", "mathematical optimization"
"model optimization" » "modeling optimization", "level optimization", "global 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: (("mathematics optimization") OR ((("model optimization") OR ("material optimization")))).
• Removing quotes may allow a broader search: (( mathematics optimization ) or ((( model optimization ) or ( material optimization )))).
• Adding a wildcard symbol may retrieve word variants: (("mathematics optimization") or ((("model optimization") or ("material optimization"))))*.