Perhaps you should try some spelling variations:
improve optimization » iterative optimization (Expand Search), model optimization (Expand Search), process optimization (Expand Search)
robust optimization » process optimization (Expand Search), robust estimation (Expand Search), joint optimization (Expand Search)
based robust » based probes (Expand Search)
linac based » lines based (Expand Search)
mod improve » may improve (Expand Search), model improves (Expand Search), model improved (Expand Search)

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: (( linac based robust optimization algorithm ) OR ( binary mod improve optimization algorithm ))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( linac based robust optimization algorithm ) OR ( binary mod improve optimization algorithm ))".
• Adding a wildcard symbol may retrieve word variants: (( linac based robust optimization algorithm ) OR ( binary mod improve optimization algorithm ))*.