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1、历年真题来源报刊阅读100篇(立体书)(1)Thermoelectrics：Every little helps HERE is a thought: approximately 60% of the energy converted in power generation is wasted. The price of energy is high, both in terms of the actual cost to the consumer and the consequences of the climate change that generating power from fos
2、sil fuels causes. If even a small proportion of this wasted heat could be converted to useful power, it would be a good thing.At this weeks meeting of the American Physical Society, in Baltimore, Mercouri Kanatzidis of Michigan State University proposed such a scheme. He advocates attaching thermoel
3、ectric devices that convert heat into electricity to chimney stacks and vehicle exhausts, to squeeze more useful energy from power generation.The technology to do so has existed for years. If one end of an electrical conductor is heated while the other is kept cool, a small voltage is created betwee
4、n the two. Placing two dissimilar metals, or other electrically conductive materials, in contact with each other and then heating them also generates a voltage. Such devices, called thermocouples, are nowadays usually made using semiconductors. They are widely used as thermometers. But if they could
5、 be made cheaper, or more efficient, or both, they could also be employed to generate power.Dr Kanatzidis is developing new thermoelectric materials designed to be capable of converting up to 20% of the heat that would otherwise be wasted into useful electricity. The challenge lies in finding a subs
6、tance that conducts electricity well and heat badly. These two properties define what physicists call the figure of merit of a thermoelectric substance, which describes the power a device made of that substance could generate. Dr Kanatzidiss group aims to make materials with higher figures of merit
7、than those attainable with todays semiconductors.Since the electrical properties of solids depend on their crystal structures, his group is experimenting with new atomic lattices. In particular, they are working on a group of chemicals called chalcogenides. These are compounds of oxygen, sulphur, se
8、lenium and tellurium that are thought to be particularly suitable for thermoelectric applications because their structure allows electric currents to flow while blocking thermal currents. They thus have a high figure of merit. Dr Kanatzidiss group is developing new ways of making these compounds cry
9、stallise correctly.But even existing devices could become economically useful as fuel prices rise, Dr Kanatzidis argues. In America, transport accounts for a quarter of the energy used. Fitting small thermoelectric devices to the exhaust pipes of vehicles could squeeze another 10% from the fuel-a sa
10、ving that would be especially relevant in hybrid petrol/electric devices where the battery is recharged in part by recycling energy that would otherwise be dissipated by energy-draining activities such as braking. Similarly, attaching thermoelectric devices to the flues of power plants could generat
11、e more useful power.And thermoelectric devices could be used in other areas. They could work alongside solar cells and solar heating systems. They could also be used in geothermal and nuclear power plants. Dr Kanatzidis argues that wherever heat is generated as part of power generation, thermoelectr
12、ic devices could help extract more useful energy. Waste not, want not.历年真题来源报刊阅读100篇(立体书)(2)Tracking your every move Some families in America and elsewhere have started buying childfriendly mobile phones outfitted with GPS (Global Positioning System) technology. These phones and their related tracki
13、ng services allow parents to pinpoint the location of their children with ease. Parents agree to pick up the phone bill in return for the reassurance of knowing where their children are; children are prepared to put up with the snooping if they are allowed to have a phone. Mobile operators in Americ
14、a are now launching tracking services. Under a federal mandate known as E911, they had to upgrade their networks to ensure that anyone dialling the 911 emergency number could be located to within 100 metres. Some operators opted for triangulation technology, which determines the location of the hand
15、set by comparing the signals received by different basestations. But Verizon and Sprint chose to adopt the more expensive but more accurate GPS technology instead, and are now looking for ways to make money from it.Verizon calls its service Chaperone. For $10 a month, parents can call up the locatio
16、n of their childs LG Migo handset from their own mobile phones, or from a PC. The child receives a message saying that the handsets position has been requested, and the parents receive an address, or a marker on a webbased ap, giving the childs location. For an extra $10 per month, they can sign up for Child Zone, a service that, among other things, fires off an alert when a youngster (or, at least, the youngsters handset) trays outside a spec
