2024年3月2日发(作者：)

让知识带有温度。

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Time to cool it

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,

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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

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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.

(830 words)

Questions 1-5

Complete each of the following statements with the scientist or

company name from the box below.

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Write the appropriate letters A-F in boxes 1-5 on your answer sheet.

A. Apple

B. IBM

C. Intel

D. Alex Mischenko

E. Ali Shakouri

F. Rama Venkatasubramanian

1. ...and his research group use paraelectric film available from the

market to produce cooling.

2. ...sold microprocessors running at 60m cycles a second in 1993.

3. ...says that he has made refrigerators which can cool the hotspots

of computer chips by 10℃.

4. ...claims to have made a refrigerator small enough to be built into

a computer chip.

5. ...attempts to produce better cooling in personal computers by

stirring up liquid with tiny jets to make sure maximum heat exchange.

Questions 6-9

Do the following statements agree with the information given in the

reading passage?

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In boxes 6-9 on your answer sheet write

TRUE if the statement is true according to the passage

FALSE if the statement is false according to the passage

NOT GIVEN if the information is not given in the passage

6. Paraelectric materials can generate a current when electrodes are

attached to them.

7. Dr. Mischenko has successfully applied his laboratory discovery

to manufacturing more efficient referigerators.

8. Doubling the frequency of logical operations inside a

microprocessor doubles the heat output.

9. IBM will achieve better computer cooling by combining

microchannels with paraelectrics.

Question 10

Choose the appropriate letters A-D and write them in box 10 on your

answer sheet.

10. Which method of disposing heat in computers may have a bright

prospect?

A. Tweaking the processors?heat sinks.

B. Tweaking the fans that circulate air over the processor抯 heat

sinks.

C. Shifting from single-core processors to systems of subunits.

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D. None of the above.

Questions 11-14

Complete the notes below.

Choose one suitable word from the Reading Passage above for each

answer.

Write your answers in boxes 11-14 on your answer sheet.

Traditional 11...pumps to drop temperature. At

present, scientists are searching for other methods to produce

refrigeration, especially in 12...materials

have been tried to generate temperature drops five times bigger than any

previously recorded. ...13...effect has also been adopted by many

researchers to cool hotspots in computers. A miniature version of a

car ...14... may also be a system to realize ideal computer cooling in the

future.

Key and Explanations:

1. D

See Paragraph 3: ...Alex Mischenko, of Cambridge University.

Using commercially available paraelectric film, he and his colleagues

have generated

2. C

See Paragraph 5: The first Pentium chips sold by Dr Moore's

company, Intel, in 1993, ran at 60m cycles a second.

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3. F

See Paragraph 8: ...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℃.

4. E

See Paragraph 8: Ali Shakouri, of the University of California, Santa

Cruz, says his are even smaller梥o small that they can go inside the chip.

5. B

See Paragraph 9: 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.

6. TRUE

See Paragraph 2: ...paraelectric materials. These act like batteries

when they undergo a temperature change: attach electrodes to them and

they generate a current.

7. FALSE

See Paragraph 3 (That may be enough to change the phenomenon

from a laboratory curiosity to something with commercial applications. )

and Paragraph 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?

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8. FALSE

See Paragraph 5: 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.

9. NOT GIVEN

See Paragraph 9: In the future, therefore, a combination of

microchannels and either thermoelectrics or paraelectrics might cool

computers.

10. D

See Paragraph 6: Tweaking the processor's heat sinks ?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?also

seems to have the end of the road in sight.

11. heat

See Paragraph 1: 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.

12. paraelectric

See Paragraph 3: Using commercially available paraelectric film, he

and his colleagues have generated temperature drops five times bigger

than any previously recorded.

13. thermoelectric

See Paragraph 7: ...the thermoelectric effect. Like paraelectric

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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.

14. radiator

See Paragraph 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.

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