16.下列有關火警探測器安裝位置的敘述，何者錯誤？ (A)安裝位置應避免靠近樑及通風管 (B)應避免空氣流可能產生逆流影響的位置 (C)應避免可能承受撞擊損傷的位置 (D)與艙壁間距離至少應1.0 m

10.Longitudinal vibration of propulsion shafting systems is often excited by the variable thrust developed by the propeller due to the non-uniform wake pattern in which it operates. The predominant periodic component of the thrust developed by a propeller occurs at blade-rate frequency, i.e., the number of propeller blades times the rotational frequency of the shaft. For a four-blade propeller running at 60 rev/min, what is the predominant periodic frequency that excites the longitudinal vibration of the propulsion shafting systems? (A)1 Hz (B)2 Hz (C)3 Hz (D)4 Hz

16.下列有關火警探測器安裝位置的敘述，何者錯誤？
(A)安裝位置應避免靠近樑及通風管
(B)應避免空氣流可能產生逆流影響的位置
(C)應避免可能承受撞擊損傷的位置
(D)與艙壁間距離至少應1.0 m

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