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今年2月22日，上海东海大桥风力发电示范工程第32、33标号的风机在拖轮拖带下由海事局巡逻艇护航，历时6h近60km的海上“行走”，安全抵达海上风电场施工吊装现场，如图所示．风电是利用风能使风机的叶片转动，带动发电装置发电的．风电场共有34台发电风机，总装机容量（总发电功率）为10.2×104kw．试解答以下问题：

（1）假设风机被拖轮匀速拖动，拖轮的输出功率为4×104w，则 风机组被拖运时受到的阻力约多大？

（2）如果风能转换为电能的效率为0.5，按年发电估算风能利用的时间为2000h，则每台风机每年利用的自然界风能为多少？

（3）风力发电有效推进低碳排放，按年发电耗煤估算，每台风机每年可节约标准煤1.8×103吨，问发电煤耗（煤质量/千瓦时）为多大？

答案

（1）风机的速度为：v=

s
t
=
60×103
6×3600
m/s=2.78m/s；

受到的阻力为：f=

P
v
=
4×104
2.78
N=1.44×104N；

（2）风的功率为P=

1.02×108
34×0.5
w=6×106w；

每台风机每年利用的风能为E风=Pt=6×106×2000×3600J=4.32×1013J；

（3）每台风机发电功率为P0=3000kw

发电煤耗=1.8×106/（3000×2000 ）kg/kwh=0.3kg/kwh   

答：（1）风机组被拖运时受到的阻力约为1.44×104；

（2）每台风机每年利用的自然界风能为4.32×1013J；

（3）发电煤耗（煤质量/千瓦时）为0.3kg/kwh．

阅读理解

阅读下列材料，从所给的六个选项（A、B、C、D、E和F）中，选出符合各小题要求的最佳选项，并在答题卡上将该项涂黑。选项中有一项为多余选项。

The following people are all searching for a university. After the description of these people, there is information about six universities A---F on your answer sheet. There is one extra paragraph about one university which you do not need to use.

小题1:Bobby is tired of working indoors and wouldn’t like to be too far away from his girlfriend who studies at Simmons.

小题2: Maria wants to learn modern science and she prefers to stay neither by the ocean nor in the northeast.

小题3:Andrew wishes to study business in a non-state-run university.

小题4: Lucy enjoys taking her further education in a women-only university.

小题5:Scott hopes to play the computer conveniently for fun.

A．SIMMONS The College of Arts and Sciences and Modern Studies. Simmons educates women to achieve their work and life goals. More than 40 majors. Lies in the heart of Boston, US. News &World Report ranks Simmons among the top state universities in the North and among the best values. 617-521-2051 www.simmons.edu.

B．PAUL SMITH’S COLLEGE The College of Nature. Experience a different kind of classroom: 15,300 acres of forests, lakes and streams, a hotel and a restaurant, 99% placement upon graduation. Two-and-four-year degree programs. PO Box 265Paul Smith, NY 12970800-421-2605 www.paulsmith.edu.

C．ST. MARY’S UNIVERSITY Personal attention. Powerful programs. Experience the technology of today at our co-educational university. One Camino Santa Utah 78228-8503 800-FOR-STMU www.stmarytx.edu.

D．NORTHERN UNIVERSITY A famous private university with 3,200 students in the Colleges of Arts & Sciences, Business and Engineering. Medicine and Law among the top ten by U.S. News & World Report Old Union 232 CA 94305-3005 650-723-2091 www.stanford.edu.E．UNIVERSITY OF PHOENIX   Adult education course. Earn an online degree with University of Phoenix today. 100% online, fast and convenient. Learn why most working professionals choose University of Phoenix Online. www.Phoenixun.edu.

F．PETER’S COLLEGE   Experienced professors are available. Equipped with a lot of modern facilities, two students a dormitory, two computers, power never fails, PO.356 Peter, 16753800-333-12-2135   www. peterun.edu.
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单项选择题

建设方案技术比选的加权平均法引入了（），对各方案予以不同的权重。

A．平滑系数

B．重要性系数

C．内部折现率

D．影子汇率换算系数
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