Perhaps you should try some spelling variations:
"varying environments and operational considerations" » "varying environments and computational considerations", "varying environments and additional considerations", "varying environment and operational considerations", "learning environments and operational considerations", "working environments and operational considerations"
"varying environments and operational definitions" » "varying environments and operational definition", "varying environments and operational decision", "varying environment and operational definitions", "learning environments and operational definitions", "working environments and operational definitions"
"varying environments and operational conditions" » "varying environments and operating conditions", "varying environments and operational control", "varying environment and operational conditions", "learning environments and operational conditions", "working environments and operational conditions"

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