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.(830 words)
雅思考试阅读真题问题
Questions 1-5
Complete each of the following statements with the scientist or company name from the box below.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.
