Perhaps you should try some spelling variations:
"modified multiobjective approximation algorithms" » "modified multiobjective optimization algorithms"
"mobile learning estimation algorithm" » "mobile learning emotion algorithm", "mobile lighting estimation algorithm", "machine learning estimation algorithm"

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• Performing a fuzzy search may retrieve terms with similar spellings: (("modified multiobjective approximation algorithms") OR ("mobile learning estimation algorithm"))~.
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• Removing quotes may allow a broader search: (( modified multiobjective approximation algorithms ) OR ( mobile learning estimation algorithm ))*.