Perhaps you should try some spelling variations:
"modified df approximation algorithm" » "modified df approximation algorithms", "modified _ approximation algorithm", "modified one approximation algorithm", "modified time approximation algorithm", "modified adam approximation algorithm", "modified bi1 approximation algorithm"
"modified adaptive quantization algorithm" » "modified adaptive estimation algorithm", "modified adaptive ventilation algorithm", "modified passive quantization 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 df approximation algorithm") OR ("modified adaptive quantization algorithm"))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"modified df approximation algorithm\") OR (\"modified adaptive quantization algorithm\"))".
• Removing quotes may allow a broader search: (( modified df approximation algorithm ) OR ( modified adaptive quantization algorithm )).
• Adding a wildcard symbol may retrieve word variants: (("modified df approximation algorithm") OR ("modified adaptive quantization algorithm"))*.