Perhaps you should try some spelling variations:
"modified objective optimisation algorithm" » "modified objective optimization algorithm", "modified multiobjective optimization algorithm", "modified objective optimization algorithms", "modified objective estimation algorithm", "modified objective estimation algorithms"
"modified staffing optimization algorithm" » "modified staffing optimization algorithms", "modified staffing estimation algorithm", "modified staffing estimation algorithms", "modified caging optimization algorithm"

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• If you are trying to use Boolean operators, they must be ALL CAPS: (("modified objective optimisation algorithm") OR ("modified staffing optimization algorithm"))~.
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