張凡講義下冊p.387
Suppose we want to use a laptop to send 100 files of approximately 40 MB each
to anothor computer over a 5 Mbit/sec wireless connection.
The laptop battery currently holds 100,000 Joules of energy.
The wireless network card alone consumes 5 watts while transmitting,
while the rest of the laptop always consumes 35 watts.
Before each file transfer we need 10 sec to choose which file to send.
(1) 略
(2)
Assume that the laptop's hard disk power consumption is no longer constant,
but varies between 6 watts when it is spinning and 1 watt when it is not
spinning. The power consumed by the laptop apart from the hard disk and
wireless card is a constant 32 watts. Suppose that the hard disk's transfer
rate is 50 MB/sec, its delay before it can begin transfer is 20 ms, and
at all other times it does not spin. How many complete files can we transfer
before the laptop's battery runs down to zero? How much energy would we need
to send all 100 files?
( Consider that the wireless card cannot send data until it is in memory. )
想請教高手第二題的算法
謝謝:)
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