成本-效益分析
参考答案:成本-效益分析:将药物治疗的成本与所产生的效益归化为以货币为单位的数字,用以评估药物治疗方案的经济性。
电路如题14图所示,线电压为380V,负载Z=44Ω,则功率表的读数应为()W。
A.0
B.1100
C.1645
D.4400
Although a given waveform may contain frequencies over a very broad range, as a practical matter any transmission system will be able to accommodate only a limited band of (86) . This, in turn, limits the data rate that can be carried on the transmission (87) A square wave has an infinite number of frequency components and hence an infinite (88) However, the peak amplitude of the kth frequency component, kf, is only l/k, so most of the (89) in this waveform is in the first few frequency components. In general, any digital waveform will have (90) bandwidth. If we attempt to transmit this waveform as a signal over any medium, the transmission system will limit the bandwidth that can be transmitted.
(89)是()
A.frequency
B.energy
C.amplitude
D.phase