首页
登录
职称英语
The development of ravel under the oceans For millennia humans h
The development of ravel under the oceans For millennia humans h
游客
2024-01-09
46
管理
问题
The development of ravel under the oceans
For millennia humans have been intrigued by what lies beneath the sea, and although sub-marine travel was attempted from time to time, it did not become commonplace until the middle of last century. Several clever and innovative people had experimented with designs for submersible boats before then, but there was much loss of life and little success.
There had long been use of a primitive diving bell for explorative purposes but it was as a war machine that the submarine came into its own. The first development in the history of American submarines was a small submersible with a hand-cranked screw-like oar and a crew of one. It was built before the American Revolutionary War (1775-1783) but was adapted for use against the British during this war. Although its pilot twice failed to fasten explosive devices to British ships before losing control of his vessel, he escaped harm.
In 1800, an American inventor, Robert Fulton, designed an underwater machine that he called the Nautilus. His version brought in features that can still be found in some modern submarines, notably adjustable diving planes for better underwater maneuvering, dual systems of propulsion, and a compressed air system that allowed it to stay down for about four hours without surfacing.
Development of submersible vessels lagged a long way behind the continued progress in the design of surface ships until the American Civil War (1861-1865) when both sides tried out various designs. One of those, called the Henley—named after its financier rather than its inventor—sank twice during training missions with 11 crew members losing their lives including Henley himself. Notwithstanding these failures, it was commissioned again in 1864 to attack ship in Charleston Harbor. A torpedo was used to strike and scuttle the ship—a first in naval history—but the submarine never reappeared and once again the whole crew perished. Its potential had been recognized but there still remained the challenge of operating safely under the water.
The US Navy could appreciate the strategic benefits of having submarines in its fleet and held a competition to encourage design and construction of these underwater craft. The inventor, John Holland, won the competition and it was his sixth prototype, the Holland, that the navy bought and added to its fleet in 1900. This submarine was quite different from previous designs. It was propelled by a gasoline engine that turned a propeller while the vessel was on the surface. When it submerged, the engine ran a generator to charge batteries to operate an electric motor. The improved propulsion methods were, unfortunately, highly dangerous. Not only is gasoline flammable and unstable, using it in the restricted environment of a submarine posed quite a hazard for the crewmen. There was another problem too: the batteries were not only heavy, cumbersome and inefficient but they were also extremely volatile.
During the same period as Holland’s efforts were being trialed, a German scientist by the name of Rudolf Diesel, created an engine which used fuel less explosive than gasoline and which could consequently be stored safely. Another advantage was that there was no necessity for an electric spark to ignite the fuel. These safety improvements combined with better fuel economy allowed Diesel engines to power a submarine for longer on the surface; however, batteries were still needed to supply energy for underwater operation.
Although diesel-powered submarines were successful and used by the US Navy for almost 50 years, the search for a single power source carried on. It wasn’t long before the concept of nuclear power was realized in Germany and taken up by an American physicist, Ross Gunn, who could envisage it potential in submerse idles. A research team was put together to adapt the concept of nuclear power for use in submarines. In effect, modern nuclear submarines have on board small nuclear power plant which produces a great amount of energy. This is used to heat water and create steam which drives a huge turbine which turns the propeller.
There have been many adaptations and technological improvements made to submarines over they ears but the shape is basically the same. Obviously, it is a totally enclosed craft, cigar-shaped with narrowed ends. The outer hull is the largest part of the boat and forms the body. The inner hull is designed to resist the considerable water pressure and insulates the crew from the cold. This is where the crew works, eats and sleeps. It also contains the engine room and the apparatus that makes clean air and clean water. Between the hulls are the ballast tanks for controlling buoyancy. There is a tall fin-shaped sail that comes up out of the hull. Inside the sail is the conning tower and extending from this, to the fore, there is a periscope (through which the captain can see the sea and sky when the submarine is near the surface of the water). Sonar is used for navigation deep below the surface. The other projection from the conning tower is the radio antenna.
Underwater, there are two controls for steering the submarine. The rudder(like a tail fin) controls side-to-side movement and diving planes influence rise and descent. There are two sets of diving planes: the forward sail planes and the stern planes, which are located at the back with the rudder and propeller.
Advancing technology will undoubtedly result in different shapes and modes of operation and it is quite possible that, in the future, submarines will be manned by robots or computer technology that communicates information to land bases via satellite.
Questions 1-6
Answer the questions below.
Choose NO MORE THAN THREE WORDS from the text for each answer.
Write your answers in boxes 1-6 on your answer sheet. [br] For what reason was Diesel’s fuel considered safer than Holland’s?
选项
答案
less explosive/volatile
解析
转载请注明原文地址:https://tihaiku.com/zcyy/3346561.html
相关试题推荐
FOSTER:DEVELOPMENT::A、immunize:resistanceB、nurture:fertilizationC、adorn:slee
Wenowknowthathumanshaveevolvednottosubsistonasingle,Paleolithicdie
Thedevelopmentofthesegenetechnologiesmaybefarinthefuture,butthemor
Althoughhumanshavemuchbiggerbrainsrelativetobodyweighttha
Althoughhumanshavemuchbiggerbrainsrelativetobodyweighttha
Althoughhumanshavemuchbiggerbrainsrelativetobodyweighttha
Informationonbehavioraldeficitsinratsisalso______tohumans,butthereis
Cometshavebeenmistakenlyinterpretedbyhumansintimespastas______ofdoom,
Theevolutionofcultureisdependentuponthedevelopmentofthetoolsofcivil
Expertsbelievethathumanshavetentrillioncellsintheirbodieswhich(i)___
随机试题
Aboy(who)youmust(meet)rightawayisFredyThompson,(thebest)mathstuden
Forthispart,youareallowed30minutestowriteanessaycommentingonth
Christmasiscelebrated(11)theworld.December25isbelievedtobetheb
[originaltext]M:Hello.W:Hello.ThisisDr.Gray’soffice.We’recallingtorem
幸运数字luckynumbers
受要约人超过承诺期限发出承诺的,除要约人及时通知受要约人该承诺有效的以外,为(
狭义中的精是()。A.水谷精微B.津液C.五脏六腑之精D.肾精E.髓
各种运输方式内外部的各个方面的构成和联系,就是( )。 A.运输系统
医学伦理学中最古老、最有生命的医德范畴是A.医疗保密 B.医疗公正 C.医疗
甲公司是一家打印机生产企业,同时生产墨盒,该公司决定将打印机价格下调,同时将墨盒
最新回复
(
0
)