VOA标准英语2015--声成像用于寻找基础设施隐藏裂缝

Sound Imaging Used to Find Hidden Cracks in Infrastructure 声成像用于寻找基础设施隐藏裂缝

Finding hidden cracks in large structures, such as bridges and airplanes, can be the difference between life and death, if the flaw leads to a catastrophic collapse¹.  Scientists at Bristol University in Britain say they have discovered a new way of looking inside crucial metal parts to identify cracks before they fail, using sound imaging.

On August 1, 2007, an eight-lane steel bridge over the Mississippi River in Minneapolis, Minnesota, collapsed² during rush hour, killing³ 13 people and injuring 145.

An investigation⁴ concluded that the main cause of the collapse were undersized elements of the bridge that simply gave way under the heavy load.

Metal fatigue⁵ like that starts with microscopic⁶ cracks that form at points of concentrated stress.

A group of scientists at Bristol University, led by senior lecturer Anthony Croxford, discovered that sending hundreds of different ultrasonic⁷ waves into a structure, and then listening and analyzing⁸ their echoes can be used to detect the tiniest cracks.

“It lets you see smaller cracks, closed cracks, cracks that, so when I say closed cracks, imagine if you have a crack in a piece of metal, it could be a bit open like that, it could have a gap in between it. If you have a gap in between it, you get reflections off the edge of it, but you don't really know how big it is," said Croxford.

Croxford says unlike purely⁹ linear systems, which create echoes of the same frequency sent into the material, his ‘phased array’ of sound-sending units returns harmonics - echoes of different frequencies.

“The nonlinear approach means that you can actually hear something from them, you're listening to different effects, rather than listening for just that echo from the crack," he said.

Using an array of attached sensors¹⁰, Croxford is testing a seemingly perfect part of a wing from an Airbus A320.  A linear system would not be able to discover cracks forming around the rivet¹¹ holes, because a hole would create one big echo.

“By using this novel approach we can now pick up a crack close to a hole, which is directly relevant, to say, aerospace¹² applications, where they're worried about cracks growing from rivet holes, things like that," said Croxford.

Croxford says the phased array system uses only one piece of equipment to get both a nonlinear and linear image.

The technology could allow inspectors¹³ to get more accurate assessments¹⁴ of damage in materials such as crucial aircraft parts, so they can be replaced before they fail.

1 collapse   

vi.累倒；昏倒；倒塌；塌陷

参考例句：

• The country's economy is on the verge of collapse.国家的经济已到了崩溃的边缘。
• The engineer made a complete diagnosis of the bridge's collapse.工程师对桥的倒塌做了一次彻底的调查分析。

2 collapsed   

adj.倒塌的

参考例句：

• Jack collapsed in agony on the floor. 杰克十分痛苦地瘫倒在地板上。
• The roof collapsed under the weight of snow. 房顶在雪的重压下突然坍塌下来。

3 killing   

n.巨额利润；突然赚大钱，发大财

参考例句：

• Investors are set to make a killing from the sell-off.投资者准备清仓以便大赚一笔。
• Last week my brother made a killing on Wall Street.上个周我兄弟在华尔街赚了一大笔。

4 investigation   

n.调查，调查研究

参考例句：

• In an investigation,a new fact became known, which told against him.在调查中新发现了一件对他不利的事实。
• He drew the conclusion by building on his own investigation.他根据自己的调查研究作出结论。

5 fatigue   

n.疲劳，劳累

参考例句：

• The old lady can't bear the fatigue of a long journey.这位老妇人不能忍受长途旅行的疲劳。
• I have got over my weakness and fatigue.我已从虚弱和疲劳中恢复过来了。

6 microscopic   

adj.微小的，细微的，极小的，显微的

参考例句：

• It's impossible to read his microscopic handwriting.不可能看清他那极小的书写字迹。
• A plant's lungs are the microscopic pores in its leaves.植物的肺就是其叶片上微细的气孔。

7 ultrasonic   

adj.超声的；n.超声波

参考例句：

• It was very necessary for people to take type-B ultrasonic inspection regularly.定期进行B超检查是十分必要的。
• Sounds are classified into two kinds: sonic and ultrasonic.声波分为两类，即普通声波与超声波。

8 analyzing   

v.分析；分析( analyze的现在分词 )；分解；解释；对…进行心理分析n.分析

参考例句：

• Analyzing the date of some socialist countries presents even greater problem s. 分析某些社会主义国家的统计数据，暴露出的问题甚至更大。 来自辞典例句
• He undoubtedly was not far off the mark in analyzing its predictions. 当然，他对其预测所作的分析倒也八九不离十。 来自辞典例句

9 purely   

adv.纯粹地，完全地

参考例句：

• I helped him purely and simply out of friendship.我帮他纯粹是出于友情。
• This disproves the theory that children are purely imitative.这证明认为儿童只会单纯地模仿的理论是站不住脚的。

10 sensors   

n.传感器，灵敏元件( sensor的名词复数 )

参考例句：

• There were more than 2000 sensors here. 这里装有两千多个灵敏元件。 来自《简明英汉词典》
• Significant changes have been noted where sensors were exposed to trichloride. 当传感器暴露在三氯化物中时，有很大变化。 来自辞典例句

11 rivet   

n.铆钉；vt.铆接，铆牢；集中(目光或注意力)

参考例句：

• They were taught how to bore rivet holes in the sides of ships.有人教他们如何在船的舷侧钻铆孔。
• The rivet heads are in good condition and without abrasion.铆钉钉头状况良好，并无过度磨损。

12 aerospace   

adj.航空的，宇宙航行的

参考例句：

• The world's entire aerospace industry is feeling the chill winds of recession.全世界的航空航天工业都感受到了经济衰退的寒意。
• Edward Murphy was an aerospace engineer for the US Army.爱德华·墨菲是一名美军的航宇工程师。

13 inspectors   

n.检查员( inspector的名词复数 )；（英国公共汽车或火车上的）查票员；（警察）巡官；检阅官

参考例句：

• They got into the school in the guise of inspectors. 他们假装成视察员进了学校。 来自《简明英汉词典》
• Inspectors checked that there was adequate ventilation. 检查员已检查过，通风良好。 来自《简明英汉词典》

14 assessments   

n.评估( assessment的名词复数 )；评价；（应偿付金额的）估定；（为征税对财产所作的）估价

参考例句：

• He was shrewd in his personal assessments. 他总能对人作出精明的评价。 来自《简明英汉词典》
• Surveys show about two-thirds use such assessments, while half employ personality tests. 调查表明，约有三分之二的公司采用了这种测评；而一半的公司则采用工作人员个人品质测试。 来自百科语句