Perhaps you should try some spelling variations:
"modified objective optimization algorithm" » "modified multiobjective optimization algorithm", "modified objective optimization algorithms", "modified objective optimisation algorithm", "modified objective estimation algorithm"
"modified carbon approximation algorithms" » "modified one approximation algorithms"

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• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"modified objective optimization algorithm\") OR (\"modified carbon approximation algorithms\"))~".
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