经济学人125:飞蛇 空中滑行

 　　Science and Technology Flying snakes Slithering through the air

　　科技 飞蛇 空中滑行

　　Fancy aerodynamics explain why some snakes are good gliders²

　　奇特的气体力学解释了为什么一些蛇善于飞行

　　MANY animals have mastered the trick of gliding³ through the forest canopy⁴. Flying frogs stretch the webbing between the toes of their enlarged feet. Some lizards⁵ spread elongated⁶ ribs⁷ covered in flaps of skin. And the colugo, a strange South-East Asian mammal, can travel as much as 70 metres (230 feet) between trees by spreading a membrane⁸ of skin that connects its limbs. Despite a lack of obvious body parts that can double up as a decent pair of wings, some snakes, too, can glide¹ for remarkable⁹ distances.

　　许多动物掌握在林冠中滑行的技巧。青蛙在飞行时展开它的脚蹼;一些蜥蜴展开皮肤软组织下的细长肋骨；猴猫，一种生长在东南亚的哺乳动物，通过伸展连接四肢的薄膜在树中滑行多达70米（230英尺）。尽管身体明显缺少一部分，如一对能够拍打且适于滑行的翅膀，一些蛇也能飞行很远。

　　To discover how snakes manage it Jake Socha of Virginia Tech and his colleagues conducted a series of test flights with paradise tree snakes, a mildly venomous variety found in parts of Asia. They launched the snakes from the top of a 15-metre tower and used four video cameras to construct 3-D images of the animals' trajectories¹⁰. The results, just published in Bioinspiration and Biomimetics, show not only that flying snakes are surprisingly good aviators¹¹ but also that they employ some complex aerodynamic tricks.

　　为了查明蛇类如何成功的飞行很远，维吉尼亚理工学院的Jake Socha和其同事用一些天堂树蛇做了一系列的飞行试验，这是一种毒性适中的蛇，它生长在亚洲部分地区。研究人员使树蛇从15米高的塔顶端飞行，过程中使用了4个摄影机拍摄蛇滑行的轨迹，以拍摄成三维立体图像。不久前在生物灵感和仿生学上发布的结果显示：飞蛇的飞行不仅令人叹为观止，并且飞行过程中使用了一些在空气动力方面的很复杂的技巧。

　　A paradise tree snake flattens¹² its body into an aerofoil-like shape that can provide a degree of lift before it takes off from a branch by jumping upwards¹³. It then falls at a steep angle and starts undulating from side to side. As it gains speed its glide path becomes shallower, allowing it to cover a greater distance. The researchers found some snakes could glide for 24 metres.

　　天堂树蛇展平它的躯体，使其形成机翼般的形状，这可以使它在借助树干弹跳前产生一定的提升力。然后它急剧下降并且不停地摆动身体。随着下降速度的增加，下滑道变得越来越浅，这使树蛇滑翔很长一段路程。研究人员发现一些树蛇可滑翔24米。

　　The 3-D analysis showed the snakes take up a staggered posture¹⁴ when gliding, with their bodies angled upwards at about 25° to the oncoming air and their heads slightly higher than their tails. Dr Socha says this orientation¹⁵ seems to provide the creatures with an aerodynamic advantage. As a result of it, the wake of air forced backwards¹⁶ by one segment of the snake's undulating body may provide extra lift to the segment behind in the sidewinding glide. Flying fish rely on a similar flow of accelerated air from their pectoral fins¹⁷ to provide lift to their smaller pelvic fins. Indeed, it is possible that the effect works both ways, and that rearward segments provide lift to those in front.

　　对三维立体图像的分析表明：树蛇滑翔过程中摆动着身体，躯体向上抬，与迎面的空气呈25度角，头部稍微高于尾部。Socha博士表示在空气动力学角度上来讲，这样的身体趋向可能会对飞行的树蛇产生推助的作用。这样，摆动树蛇的身体的前半部分擦过的空气尾流可对侧风滑行的后半部分起到提升的作用。同样，飞鱼借助胸鳍所产生的加速气流，就可以对较小的腹鳍产生一定的提升作用。事实上，反过来也可能产生这种效果，即后半部分可为前半部分起到提升作用。

　　The snakes are also surprisingly manoeuverable and have been seen to turn in mid-air. To find out if this might be deliberate, Dr Socha limited their view from the tower so that they could see only straight ahead when they launched themselves. Once airborne, and thus able to observe trees to the side of their glide-paths, some of the snakes turned towards them.

　　树蛇的飞行技巧也也令人叹为观止。人研究人员观察到它们在飞行途中可以变向。为了探明树蛇是否故意发出这一行为，Socha博士限制了树蛇在飞行时的视野，目的是让他们在起飞时只能向前看。一起飞，这些树蛇就可以看到滑行路径两旁的树，一些就转变方向朝树木飞去。

　　Dr Socha, who studies the relationship between form and function in animals, was partly funded in his snake research by America's Defence Advanced Research Projects Agency, which said it was interested in the science but obviously wonders about military applications.

　　研究动物的构成和功能的Socha 博士在对蛇进行研究时得到了美国国防发展研究项目的资助，它称它对这部分科学很感兴趣，但也明显质疑是否可以将这部分科学应用到军事领域。

　　Dr Socha does not expect to see snakelike drones in the skies soon. However, the ability to slither through holes, to swim and to climb trees and rocks, as well as to glide between elevated features of the landscape, is an attractive mixture for designers of robotic vehicles. The staggered-wing effect, in which the front of the body helps to provide lift for the back, may also be of interest to aircraft engineers. In the long term, then, the world's battlefields may see machines that resemble some people's worst nightmares, slithering as they do towards the enemy both on the ground and through the air.

　　Socha博士并未预期蛇形般的遥控飞机即将腾空出世，然而，设计集各种功能于一身的交通工具-全部自动化，能够滑穿孔洞，穿行在水中，爬得大树和岩石，滑行在凹凸不平的风景中-对于设计师来说，很具吸引力。摆动的双翼所产生的效果-机身的前半部分可为后半部分增加提升力，对飞机工程师来说也可能颇感兴趣。从长远来看，在世界战场可以看到那些出现在一些人的噩梦里的飞机，在陆地和空中滑翔，攻打敌人。

1 glide   

n./v.溜，滑行；(时间)消逝

参考例句：

• We stood in silence watching the snake glide effortlessly.我们噤若寒蝉地站着，眼看那条蛇逍遥自在地游来游去。
• So graceful was the ballerina that she just seemed to glide.那芭蕾舞女演员翩跹起舞，宛如滑翔。

2 gliders   

n.滑翔机( glider的名词复数 )

参考例句：

• The albatross is the king of gliders. 信天翁是滑翔鸟类之王。 来自《用法词典》
• For three summers, may bested and improved their gliders. 他们花了三个夏天不断地测试、改进。 来自英汉非文学 - 科学史

3 gliding   

v. 滑翔 adj. 滑动的

参考例句：

• Swans went gliding past. 天鹅滑行而过。
• The weather forecast has put a question mark against the chance of doing any gliding tomorrow. 天气预报对明天是否能举行滑翔表示怀疑。

4 canopy   

n.天篷，遮篷

参考例句：

• The trees formed a leafy canopy above their heads.树木在他们头顶上空形成了一个枝叶茂盛的遮篷。
• They lay down under a canopy of stars.他们躺在繁星点点的天幕下。

5 lizards   

n.蜥蜴( lizard的名词复数 )

参考例句：

• Nothing lives in Pompeii except crickets and beetles and lizards. 在庞培城里除了蟋蟀、甲壳虫和蜥蜴外，没有别的生物。 来自辞典例句
• Can lizards reproduce their tails? 蜥蜴的尾巴断了以后能再生吗？ 来自辞典例句

6 elongated   

v.延长，加长( elongate的过去式和过去分词 )

参考例句：

• Modigliani's women have strangely elongated faces. 莫迪里阿尼画中的妇女都长着奇长无比的脸。
• A piece of rubber can be elongated by streching. 一块橡皮可以拉长。 来自《用法词典》

7 ribs   

n.肋骨( rib的名词复数 )；（船或屋顶等的）肋拱；肋骨状的东西；（织物的）凸条花纹

参考例句：

• He suffered cracked ribs and bruising. 他断了肋骨还有挫伤。
• Make a small incision below the ribs. 在肋骨下方切开一个小口。

8 membrane   

n.薄膜，膜皮，羊皮纸

参考例句：

• A vibrating membrane in the ear helps to convey sounds to the brain.耳膜的振动帮助声音传送到大脑。
• A plastic membrane serves as selective diffusion barrier.一层塑料薄膜起着选择性渗透屏障的作用。

9 remarkable   

adj.显著的，异常的，非凡的，值得注意的

参考例句：

• She has made remarkable headway in her writing skills.她在写作技巧方面有了长足进步。
• These cars are remarkable for the quietness of their engines.这些汽车因发动机没有噪音而不同凡响。

10 trajectories   

n.弹道( trajectory的名词复数 )；轨道；轨线；常角轨道

参考例句：

• To answer this question, we need to plot trajectories of principal stresses. 为了回答这个问题，我们尚须画出主应力迹线图。 来自辞典例句
• In the space program the theory is used to determine spaceship trajectories. 在空间计划中，这个理论用于确定飞船的轨道。 来自辞典例句

11 aviators   

飞机驾驶员，飞行员( aviator的名词复数 )

参考例句：

• Analysis on Sickness Status of 1149 Aviators during Recuperation. 飞行员1149例疗养期间患病情况分析。
• In America the whole scale is too big, except for aviators. 在美国整个景象的比例都太大了，不过对飞行员来说是个例外。

12 flattens   

变平，使（某物）变平( flatten的第三人称单数 )； 彻底打败某人，使丢脸； 停止增长（或上升）； （把身体或身体部位）紧贴…

参考例句：

• After Oxford the countryside flattens out. 过了牛津以远乡村逐渐平坦。
• The graph flattens out gradually after a steep fall. 图表上的曲线突降之后逐渐趋于平稳。

13 upwards   

adv.向上，在更高处...以上

参考例句：

• The trend of prices is still upwards.物价的趋向是仍在上涨。
• The smoke rose straight upwards.烟一直向上升。

14 posture   

n.姿势，姿态，心态，态度；v.作出某种姿势

参考例句：

• The government adopted an uncompromising posture on the issue of independence.政府在独立这一问题上采取了毫不妥协的态度。
• He tore off his coat and assumed a fighting posture.他脱掉上衣，摆出一副打架的架势。

15 orientation   

n.方向，目标；熟悉，适应，情况介绍

参考例句：

• Children need some orientation when they go to school.小孩子上学时需要适应。
• The traveller found his orientation with the aid of a good map.旅行者借助一幅好地图得知自己的方向。

16 backwards   

adv.往回地，向原处，倒，相反，前后倒置地

参考例句：

• He turned on the light and began to pace backwards and forwards.他打开电灯并开始走来走去。
• All the girls fell over backwards to get the party ready.姑娘们迫不及待地为聚会做准备。

17 fins   

[医]散热片；鱼鳍；飞边；鸭掌

参考例句：

• The level of TNF-α positively correlated with BMI,FPG,HbA1C,TG,FINS and IRI,but not with SBP and DBP. TNF-α水平与BMI、FPG、HbA1C、TG、FINS和IRI呈显著正相关，与SBP、DBP无相关。 来自互联网
• Fins are a feature specific to fish. 鱼鳍是鱼类特有的特征。 来自辞典例句