Perhaps you should try some spelling variations:
"improving semantic performance series." » "improving seismic performance series.", "improving semantic affordance series.", "improving servants performance series.", "improving static performance series.", "improving semantic performance studies.", "improving semantic performance size."
"improving port performance risk." » "improving export performance risk.", "improving court performance risk.", "improving plant performance risk.", "improving port performance 2019.", "improving post performance risk.", "improving poor performance risk."

Try widening your search to All Fields.

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

• Performing a fuzzy search may retrieve terms with similar spellings: (("improving semantic performance series.") or ("improving port performance risk."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("improving semantic performance series.") OR ("improving port performance risk.")).
• Removing quotes may allow a broader search: (( improving semantic performance series. ) or ( improving port performance risk. )).
• Adding a wildcard symbol may retrieve word variants: (("improving semantic performance series.") or ("improving port performance risk."))*.