Perhaps you should try some spelling variations:
"modified changing approximation algorithms" » "modified diophantine approximation algorithms", "modified caging approximation algorithms"
"modified adaptive estimation algorithm" » "modified adaptive ventilation algorithm", "modified quantile estimation algorithm", "modified adaptive quantization algorithm", "modified passive estimation algorithm"

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: (("modified changing approximation algorithms") or ("modified adaptive estimation algorithm"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("modified changing approximation algorithms") OR ("modified adaptive estimation algorithm")).
• Removing quotes may allow a broader search: (( modified changing approximation algorithms ) or ( modified adaptive estimation algorithm )).
• Adding a wildcard symbol may retrieve word variants: (("modified changing approximation algorithms") or ("modified adaptive estimation algorithm"))*.