ИНОСТРАННЫЙ ЯЗЫК В ТЕХНИЧЕСКОМ УНИВЕРСИТЕТЕ (956018), страница 46
Текст из файла (страница 46)
Internet Video conferencing programs enable users to talk to and see each other, exchange textual and graphical information, and collaborate.
Internet TV sets allow you to surf the Web and have e-mail while you are watching TV, or vice versa. Imagine watching a film on TV and simultaneously accessing a Web site where you get information on the actors of the film. The next generation of Internet-enabled televisions will incorporate a smart-card for
261
home shopping, banking and other interactive services. Internet-enabled TV means a TV set used as an Internet device.
The Internet is a good example of a wide area network (WAN). For long-distance or worldwide communications, computers are usually connected into a wide area network to form a single integrated network. Networks can be linked together by telephone lines or fibre-optic cables. Modern telecommunication systems use fibre-optic cables because they offer considerable advantages. The cables require little physical space, they are safe as they don't carry electricity, and they avoid electromagnetic interference.
Networks on different continents can also be connected via satellites. Computers are connected by means of a modem to ordinary telephone 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 5
Harnessing (обуздание) the Speed of Light
When American engineer Alan Huang revealed his plans to build an optical computer, most scientists considered this idea as hopeless. It was impractical, if not possible, they said, to create a general-purpose computer that could use pulses of light rather than electrical signals to process data. During one of the scientist's lectures on the subject, a third of the audience walked out. At another one, some of the scientists laughed, calling the researcher a dreamer.
That was several years ago. Now the scientist demonstrated his experimental computing machine based on optics. It took him five years to develop it. The device — a collection of lasers, lenses and prisms — can serve as the basis for future optical computers 100 to 1,000 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 convert spoken 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 an impact similar to that of the integrated circuit which made small personal computers possible.
Photons, the basic unit of light beams, can in theory be much better than electrons for moving signals through a computer. First of all, photons can travel about the times as fast as electrons. And
262
while electrons react with one another, beams of photons, which have no mass or charge, can cross through one another without interference. Thus, photons can move in free space. This could open the door to radically new and different computer designs, including so-called parallel processors that could work on more than one problem at a time instead of one after another, as today's new generation computers do.
How Transistors Work
Microprocessors are essential to many of the products we use every 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 their development actually required many years of thorough research. Before transistors, computers relied on slow, inefficient vacuum tubes and mechanical switches to process information. In 1958, engineers put two transistors onto a silicon crystal and created the first integrated circuit that led to the microprocessor. Here on a tiny silicon chip there are millions of switches and pathways that help computers make important decisions and perform helpful tasks.
Transistors are miniature electronic switches. They are the building blocks of the microprocessor which is the brain of the computer. 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 transistors work, it is necessary to have an understanding of how a switched electronic circuit works. Switched electronic circuits consist of several parts. One is the circuit pathway where the electrical current flows — typically through a wire. Another is the switch, a device that 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/off switching 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 1 and the «off» state is represented by a 0. Specific sequences and patterns of Ps and 0's generated by multiple transistors can represent letters, numbers, colours and graphics. This is known as binary notation.
263
More 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 to flow through them. These are known as conductors. Materials that do 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 modulated by the introduction of impurities.
Adding certain types of impurities (примесь) to the silicon in a transistor changes its crystalline structure and improves its ability to conduct electricity.
The binary function of transistors gives microprocessors the ability to perform many tasks; from simple word processing to video editing. Microprocessors have developed to a point where transistors can carry out hundreds of millions of instructions per second on a single chip. Automobiles, medical devices, televisions, computers and even the Space Shuttle use microprocessors. They all rely on the flow of binary information made possible by the transistor.
To be read after Lesson б
Ceramic Application
The 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 for automotive 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 to remain 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 dynamically changing mechanical and thermal loads in a chemically aggressive environment.
Ceramic engines and turbines are but the top of the pyramid with respect to applications. At lower levels of performance there are numerous other applications, in which the operating conditions are less severe, for example, ceramic heat exchangers for chemical plants. Ceramics finds application in bearings and engine parts because of its high hardness and high abrasion resistance.
264
There are three main materials used in making pipes: metal, rubber and plastic.
Metal is stronger than rubber and plastic. It is also heavier and more 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 flexible than the other two materials. Rubber is the most flexible of the three materials, but it is the weakest.
Plastic is lighter than metal. It is also less expensive than steel or 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 through it, and it is very hard and therefore cannot be cut easily. But at the same 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 in fires 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, which squeeze the metal and make it longer and thinner. This method is called rolling. Not all metals can be rolled. For example, iron cannot be rolled because it is too brittle. But steel can be rolled because it is tough and malleable (ковкий) enough.
Next, the steel is cut into a flat shape. This is done by placing the sheet onto a die, and then cutting a hole in it with a punch. The method is called punching. The steel can be cut easily because it is now very thin.
Finally, the sheet steel is bent and pressed into a rounded shape. This is done by putting the sheet onto a die and then bending the sheet around the die with a press. This method is called pressing. It is not difficult to press sheet steel because it is thin and malleable.
To be read after Lesson 7
Electric Car
The electric car is not a new idea. It had success with American women in the early 1900s. Women liked electric cars because they were quiet and, what was more important, they did not pollute the
265
air. Electric cars were also easier to start than gasoline-powered ones. But the latter was faster, and in the 1920s they became much more popular.
The electric car was not used until the 1970s, when there were serious problems with the availability of oil. The General Motors Co. had plans to develop an electric car by 1980. However, soon oil became available again, and this car was never produced.
Today there is a new interest in the electric car. The Toyota Co. recently decided to spend $800 million a year on the development of new car technology. Many engineers believe that the electric car will lead to other forms of technology being used for transportation.
Car companies are working at developing a supercar. A super-efficient car will have an electric motor. Four possible power sources are being investigated. The simple one is batteries. Another possibility is fuel cells, which combine oxygen from air with hydrogen to make electricity. Yet another approach would be a flywheel (маховик), an electric generator consisting of free-spinning wheels with magnets in the rims that can produce a current. A fourth possible power source for the super-car would be a small turbine engine, running on a clean fuel like natural gas. It would run at a constant speed, generating electricity for driving vehicles or for feeding a bank of batteries, storing energy for later use.
Engines
Do you know what the first engine was like? It was called the «water wheel». This was an ordinary wheel with blades fixed to it, and the current of a river turned it. These first engines were used for irrigating fields.
Then a wind-powered engine was invented. This was a wheel, but a very small one. Long wide wooden blades were attached to it. The new engine was driven by the wind. Some of these ones can still be seen in the country.
Both of these, the water- and wind-operated engines are very economical. They do not need fuel in order to function. But they are dependent on the weather.
Many years passed and people invented a new engine, one operated by steam. In a steam engine, there is a furnace and a boiler. The furnace is filled with wood or coal and then lit. The fire heats the water in the boiler and when it boils, it turns into steam which does some useful work.
266
The more coal is put in the furnace, the stronger the fire is burning. The more steam there is, the faster a train or a boat is moving.
The steam engine drove all sorts of machines, for example, steam ships and steam locomotives. Indeed, the very first aeroplane built by A.F. Mozhaisky also had a steam engine. However, the steam engine had its disadvantages. It was too large and heavy, and needed too much fuel.
The imperfections of the steam engine led to the design of a new type. It was called the internal combustion engine, because its fuel ignites and burns inside the engine itself and not in a furnace. It is smaller and lighter than a steam engine because it does not have a boiler. It is also more powerful, as it uses better-quality fuel: petrol or kerosene.
The internal combustion engine is now used in cars, diesel locomotives and motor ships. But to enable aeroplanes to fly faster than the speed of sound another, more powerful engine was needed. Eventually, one was invented and it was given the name «jet engine». The gases in it reach the temperature of over a thousand degrees. It is made of a very resistant metal so that it will not melt.
![](https://s.studizba.com/z.php?f=/templates/si/i/noavatar.png&w=100&h=100&t=1"){kind=avatar}
