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考研英語歷年真題來源報刊閱讀100篇
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 fossil 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 week’s meeting of the American Physical Society, in Baltimore, Mercouri Kanatzidis of Michigan State University proposed such a scheme. He advocates attaching thermoelectric 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 between 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 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 substance 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 Kanatzidis’s group aims to make materials with higher figures of merit than those attainable with today’s 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, selenium 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 Kanatzidis’s group is developing new ways of making these compounds crystallise 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 saving 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 generate 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, thermoelectric devices could help extract more useful energy. Waste not, want not.
考研詞匯：
converted [k?n'v?:tid] a.更換信仰的, 修改的
advocate [?ædv?kit] n.提倡者，鼓吹者；v.提倡，鼓吹
［真題例句］One of the first advocates (n.) for a national list was a researcher at Laval University. ［2005年新題型］
［例句精譯］ Laval大學一位研究人員是首先提出創(chuàng)立全國性代理機構(gòu)的倡導者之一。
［真題例句］The journalist advocating (v.) participatory democracy in all phases of life, whose own children are enrolled in private schools.［2000年閱讀5］
［例句精譯］ 倡導終生參與民主制的新聞記者卻把自己的子女送進私立學校。
capable [?keip?b?l]a.①有本領的，有能力的；②（of）可以……的，能……的
［真題例句］I believe that the most important forces behind the massive M&A wave are the same that underlie the globalization process: falling transportation and communication costs, lower trade and investment barriers and enlarged markets that require enlarged operations capable (②) of meeting customers demands.［2001年閱讀4］
［例句精譯］ 我認為，推動這股巨大的并購浪潮的最主要的力量，也是推動全球化進程的力量，包括日趨下降的運輸與通訊費用，較低的貿(mào)易與投資壁壘，以及市場的擴大和為滿足市場需求而進行的擴大生產(chǎn)。
compound [k?m?paund]n.混合物，化合物；a.混合的，化合的，復合的；v.合成
［真題例句］Vitamins are organic compounds (n.) necessary in small amounts in the diet for the normal growth and maintenance of life of animals, including man.［1996年完形］
［例句精譯］ 維生素是有機化合物，飲食中必須含有少量維生素以維持動物（包括人）的生存和正常生長。
merit [?merit] n.優(yōu)點，價值，功績；v.值得，應得
drain［drein］n.①排水溝，陰溝；②消耗，負擔；v.排去，放干
背景常識介紹：
熱電轉(zhuǎn)換技術是一種利用半導體材料實現(xiàn)熱能和電能直接相互轉(zhuǎn)換的綠色能源技術。使用這項技術，利用農(nóng)作物、垃圾、汽車余熱甚至人體熱能，在住宅、農(nóng)莊、汽車上就可以建立一個小型發(fā)電系統(tǒng)，滿足人們對小功率電能的需求。采用不同的熱電材料可以制成發(fā)電器或者制冷器，它們無須使用傳動部件，系統(tǒng)體積小，適用溫度范圍廣，工作時無噪音，與太陽能、風能、水能等二次能源一樣，具有不排放污染物的優(yōu)點。
參考譯文：
熱電學：每一小部分都是有用的
有人認為，在發(fā)電過程中，其中大約有60%的能量在其轉(zhuǎn)化成電能時被浪費掉。無論從消費者的實際花費， 還是從用化石燃料發(fā)電所引起的氣候變化的角度而言，使用能源的代價都是很高的。如果把浪費掉的很小的一部分熱能轉(zhuǎn)換為有用的能量，這都是件好事。
美國物理學會本周在巴爾的摩舉行的例會上，密歇根州立大學的Mercouri Kanatzidis建議，把熱電轉(zhuǎn)化裝置安裝在煙囪和車輛排氣管上，從而獲得更多可用能源。
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