Perhaps you should try some spelling variations:
"improving rail performance metrics." » "improving rail performance measures.", "improving raise performance metrics.", "improving railway performance metrics.", "improving pupil performance metrics.", "improving brain performance metrics.", "improving air performance metrics."
"improving thermal performance review." » "improving thermal performance risk.", "improving thermal performance evidence.", "improving external performance review.", "improving animal performance review.", "improving erm performance review."

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

• Performing a fuzzy search may retrieve terms with similar spellings: (("improving thermal performance review.") or ("improving rail performance metrics."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("improving thermal performance review.") OR ("improving rail performance metrics."))*.
• Removing quotes may allow a broader search: (( improving thermal performance review. ) or ( improving rail performance metrics. ))*.