Task 2.1.Analyse and translate the following sentences.

1. In casting the liquid metal is caused to flow into specially designed moulds where it is cooled down acquiring the shape of the mould.2. In forming, which is contrary to casting, the solid metal is made to take the desired shape.3.Shaping the metal in the solid state may be said is always possible, all metal possessing ductility.4.Ductility or plasticity is that property of the metal which makes it acquire a desired shape when acted upon by a certain pressure.5. The ability of the solid metal to be shaped seems to be the best illustrated in the process involving plastic deformation, namely, in rolling, forging, stamping and pressing.

Task 3.Answer the questions.

1. What is the term “machining” applies to?

2. In what way is the desired shape obtained from cast, rolled and forged parts?

3. What kind of machine-tools are generally employed?

4. Which of these machine tools is considered to be the most widely used?

5. What operations are used to cause the desired property variations in metal and alloys?

6. By what means are these property variations caused?

7. Is it possible to impart the metal high mechanical properties by any other means than heat treatment?

8. What are high mechanical properties required for?

VARIANT 10

Task 1.Read and translate the text.

The wireless

To speak about the radio is to speak about its inventor- the Russian scientist A.S.Popov (1859-1906).

Having thoroughly studied the contemporary theories of electricity A.S. Popov was one of the first to use practically the results obtained by H. Hertz. In fact many scientists knew Hertz to have proved the existence of electromagnetic waves and to have studied their behavior. But it was Popov who first constructed apparatus to transmit electro-magnetic waves at a distance.

In 1895 A.S.Popov was allowed to demonstrate his device at a meeting held at St. Petersburg University. Having explained the principle of its operation the scientist informed the audience that he was going to perfect the apparatus in order to make it useful for transmitting signals by means of rapid electric oscillations. To achieve this he was going to attach to his receiver a device for recording telegrams sent over by the wire telegraph.

The new apparatus having been successfully tested in 1897,A.S.Popov demonstrated it to prove the possibility of radio communication, that is the possibility of transmitting words over a wireless telegraph. And indeed, the apparatus proved to be a success when used for communications between the shore and ships three kilometers apart. A. S. Popov wrote that he expected all the ocean-going ships to be equipped with wireless telegraph apparatuses. He hoped that with wireless telegraph apparatuses installed on all ocean-going ships the Navy would be provided with a reliable means of communication.

A year later, assisted by Ribkin and Troitsky, A.S.Popov constructed an apparatus capable of receiving audible signals. It was by means of that very radio telegraph that a battleship was saved in the Black sea. On hearing the news, Admiral Makarov declared the radio telegraph to be the great importance for the Navy and highly praised the work of its inventor, Alexander Popov.

Though Popov’s invention was of great practical importance, the tsarist government, as was often the case, did not render the Russian inventor any assistance, except that he was given permission to go on with his experiments on board of a small ship.

Three years later, having overcome many difficulties, Popov built a radio station, the first radio station in the world.

We know A.S.Popov to have been working under very hard conditions. Yet despite all hardships the scientist declined the offers of foreign commercial companies to leave Russia and lend his invention for commercial use abroad. A. S. Popov died an early death in 1905 when he was only 47 years old.

Дата добавления: 2015-11-14