首页
财务会计
医药卫生
金融经济
考公考编
外语考试
学历提升
职称考试
建筑工程
IT考试
其他
登录
职称考试
Please Fasten Your Seatbelts Severe turbulence (湍流)can kill aircraft passe...
Please Fasten Your Seatbelts Severe turbulence (湍流)can kill aircraft passe...
admin
2020-12-24
35
问题
Please Fasten Your Seatbelts
Severe turbulence (湍流)can kill aircraft passengers. Now, in test flights over the Rocky Mountains, NASA (美国航空航天局)engineers have successfully detected clear-air turbulence up to 10 seconds before an aircraft hits it.
Clear-air turbulence often catches pilots by surprise. Invisible to radar, it is difficult to forecast and can hurl (用力拋出去)passengers about the cabin. In December 1997, one passenger died and a hundred others were injured when unexpected rough air cause a United Arlines flight over the Pacific to drop 300 metres in a few seconds.
However, passengers can avoid serious injury by fastening their seatbelts. “ It is the only antidote (对策)for this sort of thing, ” says Rod Bogue,project manager at NASA’s Dryden flight Research Center in Edwards, California.
The centre’s new turbulence detector is based on lidar, or laser radar. Laser pulses are sent ahead of the plane and these are then reflected back by particles in the air. The technique depends on the Doppler effect. The wavelength of the light shifts according to the speed at which the particles are approaching. In calm air,the speed equals the plane’s airspeed. But as the particles swirl (打漩 )in rough air, their speed of approach increases or decreases rapidly. The rate of change in speed corresponds to the severity (激烈程度)of the turbulence.
In a series of tests that began last month, a research jet flew repeatedly into disturbed air over the mountain ridges (山脉)near Pueblo, Colorado. The lidar detector spotted turbulence between 3 and 8 kilometres ahead, and its forecasts of strength and duration
corresponded closely with the turbulence that the plane encountered.
Bogue says that he had “ a comfortable amount of time” to fasten his seatbelt. The researchers are planning to improve the lidar’s range with a more powerful beam. The system could be installed on commercial aircraft in the next few years.
The last paragraph tells us, among other things, that
选项
A the lidar detector needs improvement.
B many airlines are interested in the system.
C passengers often forget to fasten their seatbelts.
D the lidar detector can be used in a wide range of areas.
答案
A
解析
转载请注明原文地址:https://ti.zuoweng.com/ti/ae9QKKKQ
相关试题推荐
Sheperseveredinherideasdespiteobviousobjectionsraisedbyfriends.(20...
Sheperseveredinherideasdespiteobviousobjectionsraisedbyfriends.A.pers
Sheprseveredinherideasdespiteobviousobjectionsraisedbyfriends.A:persis
Sheperseveredinherideasdespiteobviousobjectionsraisedbyfriends.A.pers
Wouldyoupleasecallmyhusbandassoonaspossible?A:visitB:phoneC:consultD
Pleaseputupyourhandsifyouhaveanyquestions.A:raise B:reachC:wave D:fo
Pleasecallmyhusbandassoonaspossible.A:contact B:consultC:phone D:visit
Shewillbeverypleasepleasedtomeetyou.A:angry B:happyC:sad D:unwilling
Wouldyoupleasecallmyhusbandassoonaspossible?A:visitB:phoneC:consultD
Shewillbepleasedtomeetyou.A:angry B:happy C:sad D:unwilling
随机试题
对于合同解除,下列表述错误的是( )。 A、不影响合同仲裁条款的效力 B、
使用合同仓储的顾客,通常不采用()方法租用仓储空间。 A.固定租用 B.灵
A.子宫破裂 B.持续性枕横位 C.先兆子宫破裂 D.胎盘早剥 E.脐带
为避免交通事故的发生,地陪应做到()。
下列选项中属于沉积岩的有()。
当场地内有地下水时,应根据()和支护结构与基础形式等因素,确定地下水控制方法
属于超过一定规模的危险性较大的分部分项工程中的悬挑式脚手架的高度是( )。A.5m B.20mC.24m D.
男性,55岁,因高热1天来诊。查体:精神萎靡,四肢末梢凉,T36.9℃,BP80/50mmHg,右肺下背部呼吸音弱,闻湿啰音,右上腹触痛(±)。 ...
—对法国夫妇婚后移居西班牙,后来华工作。该夫妇于2011年收养一名中国儿童并决定一起回西班牙生活。根据我国法律,有关该夫妇收养中国儿童的条件和手续适用的...
项目可行性报告是项目业主进行()的必备材料。A.投资决策B.报批项目C.监控控股股东行为D.提高财务报表与信息披露的透明度E.申请贷款