Perhaps you should try some spelling variations:
"materials optimization" » "material optimization", "criteria optimization"
"modeling optimization" » "learning optimization"
"models optimization" » "model 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 ("mathematical optimization"))) OR ((("materials optimization") OR ((("models optimization") OR ("modeling optimization")))))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((\"mathematics optimization\") OR (\"mathematical optimization\"))) or (((\"materials optimization\") or (((\"models optimization\") or (\"modeling optimization\"))))))".
• Removing quotes may allow a broader search: (((( mathematics optimization ) OR ( mathematical optimization ))) or ((( materials optimization ) or ((( models optimization ) or ( modeling optimization )))))).
• Adding a wildcard symbol may retrieve word variants: (((("mathematics optimization") OR ("mathematical optimization"))) or ((("materials optimization") or ((("models optimization") or ("modeling optimization"))))))*.