01-04-2020-Орловская И.В., Самсонова Л.С. Учебник английского языка для технических университетов и вузов (6-е издание, 2006)(1) (1171846), страница 56
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Computers are connected by means of a modem to ordinarytelephone lines or fibre-optic cables, which are linked to a dish aerial. Communication satellites receive and send signals on a transcontinental scale.To be read after Lesson 5Harnessing (обуздание) the Speed of LightWhen American engineer Alan Huang revealed his plans tobuild an optical computer, most scientists considered this idea ashopeless. It was impractical, if not possible, they said, to create ageneral-purpose computer that could use pulses of light rather thanelectrical signals to process data. During one of the scientist's lectures on the subject, a third of the audience walked out.
At anotherone, some of the scientists laughed, calling the researcher a dreamer.That was several years ago. Now the scientist demonstrated hisexperimental computing machine based on optics. It took him fiveyears to develop it. The device — a collection of lasers, lenses andprisms — can serve as the basis for future optical computers 100 to1,000 times as powerful as today's most advanced supercomputers.The potential applications are remarkable: robots that can see,computers that can design aircraft, processors that can convertspoken words into written text and vice versa. Such practical optical computers are still years away — some would say light-years.Yet many scientists are predicting that the device will have animpact similar to that of the integrated circuit which made smallpersonal computers possible.Photons, the basic unit of light beams, can in theory be muchbetter than electrons for moving signals through a computer.
Firstof all, photons can travel about the times as fast as electrons. And262while electrons react with one another, beams of photons, whichhave no mass or charge, can cross through one another without interference. Thus, photons can move in free space. This could openthe door to radically new and different computer designs, includingso-called parallel processors that could work on more than oneproblem at a time instead of one after another, as today's new generation computers do.How Transistors WorkMicroprocessors are essential to many of the products we useevery day such as TVs, cars, radios, home appliances and of course,computers.
Transistors are the main components of microprocessors. At their most basic level, transistors may seem simple. But theirdevelopment actually required many years of thorough research. Before transistors, computers relied on slow, inefficient vacuum tubesand mechanical switches to process information. In 1958, engineersput two transistors onto a silicon crystal and created the first integrated circuit that led to the microprocessor.
Here on a tiny siliconchip there are millions of switches and pathways that help computersmake important decisions and perform helpful tasks.Transistors are miniature electronic switches. They are thebuilding blocks of the microprocessor which is the brain of thecomputer. Similar to a basic light switch, transistors have two operating positions, on and off.
This on/off function enables the processing of information in a computer.The only information computers understand are electrical signals that are switched on and off. To understand how transistorswork, it is necessary to have an understanding of how a switchedelectronic circuit works. Switched electronic circuits consist of several parts. One is the circuit pathway where the electrical currentflows — typically through a wire. Another is the switch, a devicethat starts and stops the flow of electrical current by either completing or breaking the circuit's pathway. Transistors have no moving parts and are turned on and off by electrical signals. The on/offswitching of transistors facilitates the work performed by microprocessors.Something that has only two states, like a transistor, can be referred to as binary. The transistor's «on» state is represented by a 1and the «off» state is represented by a 0.
Specific sequences andpatterns of I's and O's generated by multiple transistors can represent letters, numbers, colours and graphics. This is known as binarynotation.263More complex information can be created such as graphics, audio and video using the binary, or on/off action of transistors.Many materials, such as most metals, allow electrical current toflow through them.
These are known as conductors. Materials thatdo not allow electrical current to flow through them are called insulators. Pure silicon, the base material of most transistors, is considered a semiconductor because its conductivity can be modulatedby the introduction of impurities.Adding certain types of impurities (примесь) to the silicon in atransistor changes its crystalline structure and improves its abilityto conduct electricity.The binary function of transistors gives microprocessors theability to perform many tasks; from simple word processing tovideo editing. Microprocessors have developed to a point wheretransistors can carry out hundreds of millions of instructions persecond on a single chip. Automobiles, medical devices, televisions,computers and even the Space Shuttle use microprocessors.
Theyall rely on theflowof binary information made possible by the transistor.To be read after Lesson 6Ceramic ApplicationThe application which has captured the imagination of engineers, as well as the general public, is certainly the ceramic engine,that is the adiabatic turbo-diesel engine and the ceramic turbine forautomotive use. There are some successful phototypes on the road,however, applications on a large scale have been held back by problems of cost and reliability. Steady progress is being made in the increase of the reliability of ceramics.
But the cost factor is likely toremain a problem for some time.One should mention here that the long-term reliability in service still needs to be defined for those applications where the material must withstand very high temperatures and dynamicallychanging mechanical and thermal loads in a chemically aggressiveenvironment.Ceramic engines and turbines are but the top of the pyramidwith respect to applications. At lower levels of performance thereare numerous other applications, in which the operating conditionsare less severe, for example, ceramic heat exchangers for chemicalplants.
Ceramics finds application in bearings and engine parts because of its high hardness and high abrasion resistance.264There are three main materials used in making pipes: metal,rubber and plastic.Metal is stronger than rubber and plastic. It is also heavier andmore rigid than rubber and plastic. Metal is the strongest material,but it is also the heaviest, and the most rigid. It is also the most expensive of the three materials.Rubber is weaker than metal or plastic.
It is also more flexiblethan the other two materials. Rubber is the most flexible of thethree materials, but it is the weakest.Plastic is lighter than metal. It is also less expensive than steelor rubber. Plastic is the lightest material. It is also the least expensive of the three materials.Glass is used for making windows because you can see throughit, and it is very hard and therefore cannot be cut easily. But at thesame time it is very brittle and therefore it can break easily.Wood is soft and therefore it can be cut easily. It can be used infires because it is combustible.Car tyres are made of rubber because rubber is flexible.A car panel is made by three methods.
First, sheet steel is made.This is done by pushing a piece of steel between two rollers, whichsqueeze the metal and make it longer and thinner. This method iscalled rolling. Not all metals can be rolled. For example, iron cannot be rolled because it is too brittle. But steel can be rolled becauseit is tough and malleable (ковкий) enough.Next, the steel is cut into a flat shape. This is done by placingthe sheet onto a die, and then cutting a hole in it with a punch.
Themethod is called punching. The steel can be cut easily because it isnow very thin.Finally, the sheet steel is bent and pressed into a roundedshape. This is done by putting the sheet onto a die and then bending the sheet around the die with a press. This method is calledpressing. It is not difficult to press sheet steel because it is thin andmalleable.To be read after Lesson 7Electric CarThe electric car is not a new idea. It had success with Americanwomen in the early 1900s. Women liked electric cars because theywere quiet and, what was more important, they did not pollute the265air. Electric cars were also easier to start than gasoline-poweredones.
But the latter was faster, and in the 1920s they became muchmore popular.The electric car was not used until the 1970s, when there wereserious problems with the availability of oil. The General MotorsCo. had plans to develop an electric car by 1980. However, soon oilbecame available again, and this car was never produced.Today there is a new interest in the electric car.
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