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
Complete the notes below. Write NO MORE THAN TWO WORDS for each answer. Creating artificial gills Backgr
Complete the notes below. Write NO MORE THAN TWO WORDS for each answer. Creating artificial gills Backgr
admin
2014-11-08
68
问题
Complete the notes below.
Write NO MORE THAN TWO WORDS for each answer.
Creating artificial gills
Background
Taking in oxygen : mammals—lungs; fish—gills
Long-held dreams—humans swimming underwater without oxygen tanks
Oxygen tanks considered too 【L31】______and large
Attempts to extract oxygen directly from water
1960s—prediction that humans would have gills added by 【L32】______
Ideas for artificial gills were inspired by research on
fish gills
fish swim bladders
animals without gills—especially bubbles used by 【L33】______
Building a simple artificial gill
Make a watertight box of a material which lets 【L34】______ pass through
Fill with air and submerge in water
Important that the diver and the water keep 【L35】______
The gill has to have a large 【L36】______
Designers often use a network of small 【L37】______on their gill
Main limitation—problems caused by increased 【L38】______in deeper water
Other applications
Supplying oxygen for use on 【L39】______
Powering 【L40】______cells for driving machinery underwater
【L36】
Narrator: You will hear a woman giving a talk at a popular science convention. She is describing research into artificial gills designed to enable humans to breathe underwater. Now you have some time to look at Questions 31-40. Now listen, and answer Questions 31-40.
Presenter: In my talk today I’ll be exploring the idea of artificial gills. I’ll start by introducing the concept, giving some background and so forth and then I’ll go on to explain the technological applications, including a short, very simple, experiment I conducted.
Starting with the background ... As everyone knows, all living creatures need oxygen to live. Mammals take in oxygen from the atmosphere by using their lungs, and. fishes take oxygen from water by means of their gills, which of course in most fishes are located either side of their head.
But human beings have always dreamt of being able to swim underwater like the fishes, breathing without the help of oxygen tanks. I don’t know whether any of you have done any scuba diving but it’s a real pain having to use all that equipment. You need special training, and it’s generally agreed that tanks are too heavy and big to enable most people to move and work comfortably underwater. So scientists are trying a different tack: rather than humans carrying an oxygen supply as they go underwater, wouldn’t it possible to extract oxygen in situ, that is, directly from the water, whilst swimming?
In the nineteen sixties the famous underwater explorer Jacques Cousteau, for example, predicted that one day surgery could be used to equip humans with gills. He believed our lungs could be bypassed and we would learn to live underwater just as naturally as we live on land. But of course, most of us would prefer not to go to such extremes.
I’ve been looking at some fairly simple technologies developed to extract oxygen from water—ways to produce a simple, practical artificial gill enabling humans to live and breathe in water without harm. Now, how scientists and inventors went about this was to look at the way different animals handled this—fairly obviously they looked at the way fishes breathe but also how they move down and float up to the surface using inflatable sacs, called swim bladders. Scientists also looked at animals without gills, which use bubbles of air underwater, notably beetles. These insects contrive to stay underwater for long periods by breathing from this bubble which they hold under their wing cases.
…
Presenter: By looking at these animal adaptations, inventors began to come up with their own ’artificial gills’. Now making a crude gill is actually rather easy—more straightforward than you would think. You take a watertight box ... which is made of a material which is permeable to gas, that is, it allows it to pass through, inwards and outwards. You then fill this with air, fix it to the diver’s face and go down underwater. But a crucial factor is that the diver has to keep the water moving, so that water high in oxygen is always in contact with the gill, so he can’t really stay still. And to maximise this contact it’s necessary for your gill to have a big surface area. Different gill designers have addressed this problem in different ways but many choose to use a network or lattice-arrangement of tiny tubes as part of their artificial gills. Then the diver is able to breathe in and out—oxygen from the water passes through the outer walls of the gill and carbon-dioxide is expelled. In a nut-shell, that’s how the artificial gill works.
So, having read about these simple gill mechanisms, I decided to create my own. I followed the procedure I’ve just described and it worked pretty well when I tried it out in the swimming pool ... I lasted underwater for nearly forty minutes! However, I’ve read about other people breathing through their gill for several hours.
So the basic idea works well, but the real limitation is that these simple gills don’t work as the diver descends to any great depth because the pressure builds and a whole different set of problems are caused by that... Research is being done into how these problems might be overcome... but that’s another story which has to be the subject of another talk!
Despite this serious limitation, many people have high hopes for the artificial gill and they think it might have applications beyond simply enabling an individual to stay underwater for a length of time. For example, the same technology might be used to provide oxygen for submarines ... enabling them to stay submerged for months on end without resorting to potentially dangerous technologies such as nuclear power. Another idea is to use oxygen derived from the water as energy for fuel cells. These could power machinery underwater, such as robotic devices...
So, in my view, this is an area of technology with great potential. Now, if anyone has any questions, I’d be happy to answer...
选项
答案
surface area
解析
转载请注明原文地址:https://kaotiyun.com/show/iiAO777K
本试题收录于:
雅思听力题库雅思(IELTS)分类
0
雅思听力
雅思(IELTS)
相关试题推荐
ElizabethBishop’sCompletePoems(1927-1979)hascometoseemtomostofitsreaderssoachievedandsufficientasalife’swork
Inmanycountrieschildrenareengagedinsomekindofpaidwork.Somepeopleregardthisascompletelywrong,whileotherscons
READINGPASSAGE1Youshouldspendabout20minutesonQuestions1-13,whicharebasedonReadingPassage1below. Fro
READINGPASSAGE2Youshouldspendabout20minutesonQuestions14-26,whicharebasedonReadingPassage2below.
READINGPASSAGE1Youshouldspendabout20minutesonQuestions1-13,whicharebasedonReadingPassage1below.
Questions28-29Completethenotes,whichshowhowtheapproachestodefining’talent’havechanged.ChooseONEorTWOWORDSfro
Questions28-29Completethenotes,whichshowhowtheapproachestodefining’talent’havechanged.ChooseONEorTWOWORDSfro
Questions28-29Completethenotes,whichshowhowtheapproachestodefining’talent’havechanged.ChooseONEorTWOWORDSfro
随机试题
投资组合管理的一般流程不包括()。
与动脉粥样硬化密切有关的物质是
对于阴道癌淋巴转移。错误的是
A.进口检验B.抽查性检验C.委托检验D.复验E.注册检验因不具备条件,请药品检验所进行的检验是()。
听音室或立体声控制室的混响时间在()左右,背景噪声满足噪声评价曲线NR-15。
已知某企业上年的营业净利率为10%,总资产周转次数为1次,年末资产负债率为50%,利润留存率为50%,假设保持上年的经营效率和财务政策不变,并且不增发新股和回购股票,则今年企业的销售增长率为()。
经常用于非管理人员招聘的员工招聘方法是()
媒体暴力一直是社会和相关领域学者关注的热点问题之一,网络背景下的暴力视频游戏如何影响攻击性行为更是当前研究的重要主题。有研究认为暴力视频游戏会增加个体的攻击性(Greitemeyter&Mugge,2014),但少有研究从虚拟化身(指个体在虚拟环境中
某市警察局的统计数字显示,汽车防盗装置降低了汽车被盗的危险性。但是汽车保险业却不以为然,它们声称,装了汽车防盗装置的汽车反而比那些没有装此类装置的汽车更有可能被偷。下面哪一项如果正确,最能解释这个明显的矛盾?
在VisuMFoxPro中,程序中不需要用PUBLIC等命令明确声明和建立,可直接使用的内存变量是()。
最新回复
(
0
)