Perhaps you should try some spelling variations:
"relating machines using vibration signals" » "welding machine using vibration signals", "cleaning machines using vibration signals", "milling machines using vibration signals", "relating machines using vibration signal"
"rotating machinery using vibration signals" » "coating machinery using vibration signals", "rotation machinery using vibration signals", "rotating machinery using vibration signal"

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• Performing a fuzzy search may retrieve terms with similar spellings: (("rotating machinery using vibration signals") or ("relating machines using vibration signals"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("rotating machinery using vibration signals") OR ("relating machines using vibration signals")).
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• Adding a wildcard symbol may retrieve word variants: (("rotating machinery using vibration signals") or ("relating machines using vibration signals"))*.