Perhaps you should try some spelling variations:
"modified coverage approximation algorithms" » "modified average approximation algorithms"
"modified adaptive ventilation algorithm" » "modified adaptive estimation algorithm", "modified adaptive estimation algorithms", "modified adaptive evolution algorithm", "modified adaptive quantization algorithm", "modified invasive ventilation algorithm", "modified passive ventilation algorithm"

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

• Performing a fuzzy search may retrieve terms with similar spellings: (("modified coverage approximation algorithms") or ("modified adaptive ventilation algorithm"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("modified coverage approximation algorithms") OR ("modified adaptive ventilation algorithm"))*.
• Removing quotes may allow a broader search: (( modified coverage approximation algorithms ) or ( modified adaptive ventilation algorithm ))*.