2017年雅思閱讀練習(xí)試題
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★Time to cool it
Dec 13th 2006
From The Economist print edition
1 REFRIGERATORS are the epitome of clunkytechnology: 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 basedon a robust and effective idea--draw heat from thething you want to cool by evaporating a liquid next to it, and then dump that heat by pumpingthe vapour elsewhere and condensing it. This method of pumping heat from one place toanother served mankind well when refrigerators’ main jobs were preserving food and, as airconditioners, cooling buildings. Today’s high-tech world, however, demands high-techrefrigeration. Heat pumps are no longer up to the job. The search is on for something toreplace them.
2 One set of candidates are known as paraelectric materials. These act like batteries whenthey undergo a temperature change: attach electrodes to them and they generate acurrent. This effect is used in infra-red cameras. An array of tiny pieces of paraelectric materialcan sense the heat radiated by, for example, a person, and the pattern of the array’s electricaloutputs can then be used to construct an image. But until recently no one had bothered muchwith the inverse of this process. That inverse exists, however. Apply an appropriate currentto a paraelectric material and it will cool down. 3 Someone who is looking at this inverse effect isAlex Mischenko, of Cambridge University. Using commercially available paraelectric film, he andhis colleagues have generated temperature drops five times bigger than any previouslyrecorded. That may be enough to change the phenomenon from a laboratory curiosity tosomething 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 inmore efficient domestic fridges and air conditioners. The real money, though, may be incooling computers. 5 Gadgets containing microprocessors have been getting hotter for a longtime. One consequence of Moore’s Law, which describes the doubling of the number oftransistors on a chip every 18 months, is that the amount of heat produced doubles as well. Infact, it more than doubles, because besides increasing in number, the components are gettingfaster. Heat is released every time a logical operation is performed inside a microprocessor, sothe faster the processor is, the more heat it generates. Doubling the frequency quadruples theheat output. And the frequency has doubled a lot. The first Pentium chips sold by Dr Moore’scompany, 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. Tweakingthe processor’s heat sinks (copper or aluminium boxes designed to radiate heat away) hasreached its limit. So has tweaking the fans that circulate air over those heat sinks. And theidea of shifting from single-core processors to systems that divided processing powerbetween first two, and then four, subunits, in order to spread the thermal load, also seems tohave the end of the road in sight.
7 One way out of this may be a second curious physical phenomenon, the thermoelectriceffect. Like paraelectric materials, this generates electricity from a heat source and producescooling from an electrical source. Unlike paraelectrics, a significant body of researchers isalready working on it.
8 The trick to a good thermoelectric material is a crystal structure in which electrons canflow freely, but the path of phonons--heat-carrying vibrations that are larger than electrons--isconstantly interrupted. In practice, this trick is hard to pull off, and thermoelectric materialsare thus less efficient than paraelectric ones (or, at least, than those examined by DrMischenko). Nevertheless, Rama Venkatasubramanian, of Nextreme Thermal Solutions in NorthCarolina, claims to have made thermoelectric refrigerators that can sit on the back of computerchips and cool hotspots by 10℃. Ali Shakouri, of the University of California, Santa Cruz, sayshis 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 aheat pump--a miniature version of a car radiator. Last year Apple launched a personalcomputer that is cooled by liquid that is pumped through little channels in the processor, andthence to a radiator, where it gives up its heat to the atmosphere. To improve on this, IBM’sresearch laboratory in Zurich is experimenting with tiny jets that stir the liquid up and thusmake sure all of it eventually touches the outside of the channel--the part where the heatexchange takes place. In the future, therefore, a combination of microchannels and eitherthermoelectrics or paraelectrics might cool computers. The old, as it were, hand in hand with thenew.
(830 words)
Questions 1-5
Complete each of the following statements withthe scientist or company name from the box below.
Write the appropriate letters A-F in boxes 1-5on 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 producecooling.
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 by10℃.
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 withtiny jets to make sure maximum heat exchange.
Questions 6-9
Do the following statements agree with the information given in the reading passage?
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 moreefficient referigerators.
8. Doubling the frequency of logical operations inside a microprocessor doubles the heatoutput.
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.
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 refrigerators use...
11...pumps to drop temperature. At present, scientists are searching for other methodsto produce refrigeration, especially in computer microprocessors....
12...materials have been tried to generate temperature drops five times bigger than anypreviously recorded. ...
13...effect has also been adopted by many researchers to cool hotspots in computers. Aminiature 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, ofCambridge University. Using commercially availableparaelectric film, he and his colleagues havegenerated temperature drops...
2. C
See Paragraph 5: The first Pentium chips sold byDr Moore’s company, Intel, in 1993, ran at 60mcycles a second.
3. F
See Paragraph 8: ...Rama Venkatasubramanian, of Nextreme Thermal Solutions in NorthCarolina, claims to have made thermoelectric refrigerators that can sit on the back of computerchips and cool hotspots by 10℃. 4. E
See Paragraph 8: Ali Shakouri, of the University of California, Santa Cruz, says his are evensmaller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 experimentingwith tiny jets that stir the liquid up and thus make sure all of it eventually touches theoutside 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 atemperature 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 laboratorycuriosity to something with commercial applications. ) and Paragraph 4 (As to what thoseapplications might be, Dr Mischenko is still a little hazy. He has, nevertheless, set up acompany to pursue them. He foresees putting his discovery to use in more efficient domesticfridges? 8. FALSE
See Paragraph 5: Heat is released every time a logical operation is performed inside amicroprocessor, so the faster the processor is, the more heat it generates. Doubling thefrequency quadruples the heat output. 9. NOT GIVEN
See Paragraph 9: In the future, therefore, a combination of microchannels and eitherthermoelectrics or paraelectrics might cool computers.
10. D
See Paragraph 6: Tweaking the processor’s heat sinks ?has reached its limit. So hastweaking 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. Heatpumps 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 havegenerated temperature drops five times bigger than any previously recorded.
13. thermoelectric
See Paragraph 7: ...the thermoelectric effect. Like paraelectric materials, this generateselectricity from a heat source and produces cooling from an electrical source. Unlikeparaelectrics, 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 lesstechy than a heat pump--a miniature version of a car radiator.
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