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