首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
Please Fasten Your Seatbelts Severe turbulence(湍流)can kill aircraft passengers. Now, in test flights over the Rocky Mountain
Please Fasten Your Seatbelts Severe turbulence(湍流)can kill aircraft passengers. Now, in test flights over the Rocky Mountain
admin
2014-09-13
79
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(用力抛出去)passengers about the cabin. In December 1997, one passenger died and a hundred others were injured when unexpected rough air caused a United Airlines flight over the Pacific to drop 300 meters 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 Center’ 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(多普勒效应). 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 kilometers 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 turbulence detector can tell the severity of the turbulence by measuring
选项
A、the speed of the plane
B、the speed of the light
C、the number of particles in the air
D、the changes of the particles’ speed
答案
D
解析
根据第四段最后一句可知,晴空湍流的强度与微粒速度的变化有关。
转载请注明原文地址:https://kaotiyun.com/show/0XQd777K
本试题收录于:
职称英语理工类C级题库职称英语分类
0
职称英语理工类C级
职称英语
相关试题推荐
Thestorywasverytouching.
ThepassageindicatesthatancienttreatmentsforinjuryanddiseasewereItcanbeseenfromthepassagethattheearth’ssupp
InitiallythewriterdidnotwanttobuyahearingaidbecauseWhichofthefollowingisNOTtrueofCrystalEar?
Thiskindofanimalbecameextinctabout500yearsago.
Theattitudeoftheauthorofthispassagetowardthesaltcontroversyisthat______。Cannedgoodsshouldhavethesametypeof
Sincespeechissuchafamiliaractivity,itisoftenregardedasauniversalendowment.
Theyconvertedthesparebedroomintoanoffice.
StomachUlcerStomachulcersarethecauseofseverepainformanypeople.Doctorshavebeenabletohelplessenthepainof
WinstonChurchillgaveamovingspeech.
Practicallyallspeciesofanimalscommunicateeitherthroughsoundsorthroughalargerepertoryofsoundlesscodes.
随机试题
寒热证的鉴别要点是
面对当事人的下列做法,法院应当不予准许的是?
下列哪一选项符合规章制定的要求?(卷二真题试卷第39)
根据《房屋建筑与装饰工程工程量计算规范》,措施项目中安全文明施工的“四口”是()。
要保持一国长期的经济增长,政府可以选择的经济政策包括()。
关于期货市场,下列说法正确的有()。
王某担任某县高二英语教师期问通过了硕士研究生入学考试,学校以王某服务期未满,学校英语教师不足为由不予批准王某在职学习。王某欲以剥夺其参加进修权利为由提出申诉,受理申诉的机构应当是()。
教授创造性思维的策略和方法中,()的主要目的是发展学生的想象力和对事物的敏感性,并促使学生深入思考,灵活应对。
新郎经过紧张的筹备准备迎娶新娘,婚礼当天迎亲车队到达时,新娘因移情别恋飞往国外,新娘家人转告新郎随后办理离婚手续。此事对新郎造成了严重伤害。法院认为新娘违背了诚实信用原则和公序良俗原则,侮辱了新郎的人格尊严,判决新娘赔偿新郎财产损失和精神抚慰金。关于本案,
属于特殊商品的有()
最新回复
(
0
)