雅思阅读模拟题及答案|雅思阅读模拟题：Timetocoolit

【#雅思# 导语】®文档大全网为大家准备了雅思阅读模拟题：Time to cool it。雅思模拟试题在雅思备考过程中所起的作用不可小觑，通过模拟练习题，我们可以很直接地了解到自己的备考状况，从而可以更有针对性地进行之后的复习。希望以下内容能够对大家的雅思备考有所帮助!更多雅思报名的最新消息，最专业的雅思备考资料，®文档大全网将为大家发布。

　　Dec 13th 2006

　　From The Economist print edition

　　1 REFRIGERATORS are the epitome of clunky technology: solid, reliable and
just a little bit dull. They have not changed much over the past century, but
then they have not needed to. They are based on a robust and effective
idea--draw heat from the thing you want to cool by evaporating a liquid next to
it, and then dump that heat by pumping the vapour elsewhere and condensing it.
This method of pumping heat from one place to another served mankind well when
refrigerators' main jobs were preserving food and, as air conditioners, cooling
buildings. Today's high-tech world, however, demands high-tech refrigeration.
Heat pumps are no longer up to the job. The search is on for something to
replace them.

　　2 One set of candidates are known as paraelectric materials. These act like
batteries when they undergo a temperature change: attach electrodes to them and
they generate a current. This effect is used in infra-red cameras. An array of
tiny pieces of paraelectric material can sense the heat radiated by, for
example, a person, and the pattern of the array's electrical outputs can then be
used to construct an image. But until recently no one had bothered much with the
inverse of this process. That inverse exists, however. Apply an appropriate
current to a paraelectric material and it will cool down.

　　3 Someone who is looking at this inverse effect is Alex Mischenko, of
Cambridge University. Using commercially available paraelectric film, he and his
colleagues have generated temperature drops five times bigger than any
previously recorded. That may be enough to change the phenomenon from a
laboratory curiosity to something with commercial applications.

　　4 As to what those applications might be, Dr Mischenko is still a little
hazy. He has, nevertheless, set up a company to pursue them. He foresees putting
his discovery to use in more efficient domestic fridges and air conditioners.
The real money, though, may be in cooling computers.

　　5 Gadgets containing microprocessors have been getting hotter for a long
time. One consequence of Moore's Law, which describes the doubling of the number
of transistors on a chip every 18 months, is that the amount of heat produced
doubles as well. In fact, it more than doubles, because besides increasing in
number, the components are getting faster. Heat is released every time a logical
operation is performed inside a microprocessor, so the faster the processor is,
the more heat it generates. Doubling the frequency quadruples the heat output.
And the frequency has doubled a lot. The first Pentium chips sold by Dr Moore's
company, Intel, in 1993, ran at 60m cycles a second. The Pentium 4--the last
"single-core" desktop processor--clocked up 3.2 billion cycles a second.

　　6 Disposing of this heat is a big obstruction to further miniaturisation
and higher speeds. The innards of a desktop computer commonly hit 80℃. At 85℃,
they stop working. Tweaking the processor's heat sinks (copper or aluminium
boxes designed to radiate heat away) has reached its limit. So has tweaking the
fans that circulate air over those heat sinks. And the idea of shifting from
single-core processors to systems that divided processing power between first
two, and then four, subunits, in order to spread the thermal load, also seems to
have the end of the road in sight.

　　7 One way out of this may be a second curious physical phenomenon, the
thermoelectric effect. Like paraelectric materials, this generates electricity
from a heat source and produces cooling from an electrical source. Unlike
paraelectrics, a significant body of researchers is already working on it.

　　8 The trick to a good thermoelectric material is a crystal structure in
which electrons can flow freely, but the path of phonons--heat-carrying
vibrations that are larger than electrons--is constantly interrupted. In
practice, this trick is hard to pull off, and thermoelectric materials are thus
less efficient than paraelectric ones (or, at least, than those examined by Dr
Mischenko). Nevertheless, Rama Venkatasubramanian, of Nextreme Thermal Solutions
in North Carolina, claims to have made thermoelectric refrigerators that can sit
on the back of computer chips and cool hotspots by 10℃. Ali Shakouri, of the
University of California, Santa Cruz, says his are even smaller--so small that
they can go inside the chip.

　　9 The last word in computer cooling, though, may go to a system even less
techy than a heat pump--a miniature version of a car radiator. Last year Apple
launched a personal computer that is cooled by liquid that is pumped through
little channels in the processor, and thence to a radiator, where it gives up
its heat to the atmosphere. To improve on this, IBM's research laboratory in
Zurich is experimenting with tiny jets that stir the liquid up and thus make
sure all of it eventually touches the outside of the channel--the part where the
heat exchange takes place. In the future, therefore, a combination of
microchannels and either thermoelectrics or paraelectrics might cool computers.
The old, as it were, hand in hand with the new.

本文来源：https://www.wddqw.com/U0B5.html