I. Переведите следующие предложения на русский язык.

1. Scientists and mathematicians do help one another in making discoveries and solving problems.

2. It would take too much time to carry out complicated calculations unless the computers were constructed.

3. Germanium was predicted by Mendeleev, the German scientist Winkler discovering it seventeen years later.

4. Variations of current flowing in one part of the transistor circuit are known to cause corresponding changes in the other part of the circuit.

5. Electrons can be made to travel at very high speeds.

6. Popov's having invented the radio is well-known to everybody.

7. A gas is generally considered to have two definite specific heats, depending on the manner in which it is heated. A gas may be heated at constant volume or it may be heated at constant pressure, each method giving a different value for the specific heat.

8. The junction transistor proved to be most effective as a low and a medium frequency amplifier.

9. The conductivity of minerals and crystals increases with heating and falls with cooling.

10. When manufactured with a controlled amount of arsenic impurity, germanium is called n -type germanium, the letter n standing for negative.

11. The work of Rutherford followed by great research work of many other scientists is known to every physicist.

12. A gas being heated at constant volume, no work is done by it, as there is no change of volume. The specific heat to be obtained by this method of heating is known as the specific heat at constant volume.

13. We know the transformer to be an apparatus designed for changing the alternating voltages and currents by means of magnetic induction, the frequency remaining unchanged.

14. Transformers being generally used only with alternating current, there is no need to make and break the circuit.

15. The amount of energy to be consumed by the motor is equal to that put into the motor.

16. Some gaseous reactions are not all influenced by changes in pressure.

17. To produce a current by chemical reaction an alkali or an acid is made to react with a metal. The device to be used is called a voltaic or an electric cell, a group of two or more cells connected together forming a battery.

18. The current decreasing, an e.m.f. is induced in the direction which coincides with that of the current, thus opposing the decrease of current.

19. If we were asked to prove the existence of a connection between electricity and magnetism, we could not do better than point to the electromagnet. It is flow of current in the conductor of that device which produces a magnetic effect.

20. Unless the battery terminals were connected to a closed circuit, there would be no movement of electrons from the negative to the positive terminal.

21. At any rate, the sum total of the chemical energy is computed to equal the sum total of all the other forms of energy into which it is converted.

22. Connecting the two terminals in a closed circuit leads to a steady flow of electric current from one terminal to the other.

23. The flow of electrons from the zinc plate to the copper plate in the external circuit was found to represent electrical energy.

24. Eight turns of the coil would cause the current to turn through the coil eight times. This would give eight times the magnetic field strength, that is, with a given current flowing around the coil, the magnetic field strength is known to be directly proportional to the number of turns of wire.

25. It is the e.m.f. that moves electrical charges from one point in the circuit to another.

26. The greater the current in the coil, the greater the force and, therefore, the greater the angle of rotation of the armature.

27. An iron wire of the same size and length as a copper one is observed to have a greater resistance than that of the copper wire. At any rate, under the same conditions the copper wire will allow more current to flow than the iron wire does.

28. It is supposed that the electromotive force is named so because of the idea that it "forces" the current through the circuit.

29. For instance, a copper wire conducts electricity readily, glass seems to conduct so little current that it is hardly measurable.

30. It would be quite wrong to think that conducting materials are the only materials to be used for power transmission.

31. In the transmission of power we generally employ the best conductor available in order that as little power as possible might be lost in heating the transmission line.

32. Epinus was the first to apply mathematics to the study of electricity and magnetism. But what interests us most is that he first investigated the phenomenon known at present as that of electrostatic induction.

33. Magnetism manifests itself as if it existed in lines emanating from the magnetic materials or current carrying conductors, these lines being called magnetic lines of force.

34. Air being the source of the oxygen required to produce the combustible mixture is, therefore, equally a part of the fuel as are the other materials already mentioned. Thus, an air jet to be introduced into an atmosphere of, say, coal gas will burn in an identical manner to a gas jet in air.

35. Adding heat to a boiling liquid we make it change its state without altering its temperature. The quantity of heat required to transform the unit mass of a substance from the liquid state into vapour without changing temperature is known to be called latent heat of vaporization of the substance.

Тексты для анализа и перевода

 

Text 1

A primer on air compressors

Compressed air has become one of the most important power media used in industry. What makes the compression process tick? Two basic types of machines compress ambient air for industrial use: positive-displacement and dynamic air compressors.

In positive-displacement compressors, ambient air is isolated in a volume that subsequently is mechanically reduced to increase the air's pressure. The action may use a crankshaft and reciprocating pistons — much like the familiar internal combustion engine — or rotary elements. The most common rotary elements are sliding vanes that move radially, and male and female rotors that mesh as they turn.

In dynamic compressors, the mechanical action of rotating impellers accelerates ambient air as it passes through the machine. The additional kinetic energy is converted into pressure energy downstream. Dynamic compressors are identified as centrifugal or axial — depending on the manner in which air flows through them.

Thermodynamics

The various compression processes are based on the ideal gas laws of thermodynamics. Neither air nor other gases meet all the assumptions implied in these perfect gas laws. However, some knowledge of these laws can be combined with information gained from experimentation to permit an engineering analysis of the compression process.

Compression efficiency in any compressor is compared with two theoretical standards — isothermal and adiabatic. (Neither type occurs in an actual compressor because of the unavoidable losses of the real world.) Isothermal compression would occur if the air temperature were kept constant as pressure increases. To keep temperature constant, the heat of compression would have to be removed continually. This perfect cooling cannot be accomplished in actual practice. The isothermal equation is a statement of Boyle's Law:

P₁V₁=P₂V₂

Adiabatic compression would occur if there were no gain or loss of heat during the process. True adiabatic compression also is not attained in practice, but the compression cycle of most well-designed positive-displacement compressors does approximate an adiabatic cycle. The adiabatic equation is:

P₁V₁^k=P₂V₂^k

where k is the ratio of the specific heat at constant pressure to the specific heat at constant volume, c_p/c_v. For dry air, k ≈ 1.4.

 

1. Выпишите из текста сказуемые в страдательном залоге, имеющие в своем составе модальный глагол, и переведите их вместе с подлежащими.

2. Выпишите из текста предложения, в которых употребляются формы сослагательного наклонения, и переведите их.

3. Найдите в тексте инфинитивы в функции обстоятельства и переведите их вместе с относящимися к ним словами.

4. Выпишите из последнего абзаца предложение с глаголом to do, определите его функцию и переведите предложение.

5. Выпишите из текста причастия I, определите их функцию и перведите вместе с относящимися к ним словами.

6. Выпишите из последнего предложения второго абзаца придаточные предложения и переведите их.

7. Выпишите из третьего абзаца as с относящимися словами и переведите их.

8. Переведите текст с учетом выполненных заданий.

 

Text 2

A primer on air compressors (continued)

Reciprocating compressors

Historically the most widely used industrial air compressor, reciprocating machines are offered in more models and sizes than perhaps any other type. Horsepower ratings range from fractional to 12,000 and more; available pressures can be 6000 psi and higher. This variety makes it possible to find a reciprocating compressor small enough to operate a single function on a machine or large enough to supply an entire facility. A number of different physical configurations may even make it possible to match a compressor to the particular space where it must be installed. Reciprocators are the most efficient compressors for the majority of applications. They can be fitted with control systems which match their output almost exactly to operating demands. Modern electronic pressure sensors join sophisticated computer-control systems to sequence a gang of different-size air compressors for maximum efficiency.

Reciprocating compressors have one or more cylinders, each fitted with a piston driven by a crankshaft through a connecting rod. Each cylinder also has intake and discharge valves, and some means for cooling the mechanical parts. Ambient fluid is drawn into the cylinder during its suction stroke. At the end of the suction stroke, the crankshaft reverses the piston's direction and the fluid is compressed and expelled during the discharge stroke.

When only one end of the piston contacts the fluid, the compressor is identified as single-acting. When both ends of the piston act on the fluid, the compressor is double-acting. Obviously, a double-acting compressor discharges approximately twice as much fluid per cylinder per cycle as a comparable-size single-acting machine.

As in other high-cycling machines, lubrication and cooling are important to the operation of reciprocating compressors. Depending on compressor size, splash lubrication, pressurized crankcases, or pumped lubrication may provide the former of these functions. Water is the most-common coolant for air-compressor cylinders, intercoolers, and aftercoolers, although some smaller models may be air-cooled.

 

1. Выпишите из первого абзаца инфинитивы в функции обстоятельства следствия и переведите их вместе с относящимися к ним словами.

2. Найдите в тексте предложение с независимым причастным оборотом и переведите его.

3. Выпишите из текста все сказуемые в страдательном залоге и переведите их вместе с подлежащими.

4. Выпишите из последнего абзаца причастие I, определите его функцию и переведите вместе с относящимися к нему словами.

5. Выпишите из текста именные группы и переведите их.

6. Выпишите из текста герундии, укажите их функции и переведите их вместе с относящимися к ним словами.

7. Выпишите из текста предложения с as и переведите их.

8. Переведите текст с учетом выполненных заданий.

 

Text 3

A primer on air compressors (continued)

Centrifugal compressors

Centrifugal compressors develop pressure within themselves, independent of load — but the load determines the flow to be handled. This general statement is, of course, limited by the physical size of the machine and the power of its driver.

In its simplest form, a centrifugal compressor is a single-stage, single-flow machine with its impeller overhung on its drive. Air enters the unit through the inlet nozzle, which is proportioned so that the air arrives at the impeller with a minimum of shock and turbulence. The impeller receives air from the inlet nozzle and dynamically compresses it. The impeller also sets the air in motion, achieving a velocity somewhat less than the tip speed of the impeller.

A diffuser chamber surrounds the impeller and receives air leaving the impeller. The diffuser serves to gradually reduce the velocity of the air and convert its velocity energy to a higher pressure level. A volute casing surrounds the diffuser and repeats the procedure, collecting the air, reducing its velocity further, and recovering additional velocity energy.

The stresses permissible in the impeller limit the maximum discharge pressure that may be obtained from this single-stage unit. For higher pressures, staging again is the answer, with multiple impellers and passages to take air from each diffuser to the inlet of the succeeding stage.

Axial compressors accelerate the air in a direction generally parallel to the rotating shaft. Each pair of rotating and stationary blades form a stage, but pressure rise per stage is small, so the usual axial compressor must have multiple stages to produce typical shop air.

While centrifugal machines deliver practically constant pressure over a considerable range of capacities, axial compressors have a substantially constant flow delivery at variable pressures. Note that these characteristics also mean the flow from a centrifugal compressor must be greatly reduced to increase the pressure ratio, while an axial compressor can develop a substantial increase in pressure with a modest reduction in flow rate. In general, centrifugal machines have a wider stable range than axial compressors.

 

1. Выпишите из первого предложения первого абзаца инфинитив, определите его функцию и переведите вместе с относящимися к нему словами.

2. Выпишите из текста сказуемые в страдательном залоге, имеющие в своем составе модальные глаголы, и переведите их вместе с подлежащими.

3. Выпишите из текста все причастия I, укажите их функцию и переведите их вместе с относящимися к ним словами.

4. Выпишите из четвертого абзаца предложение с герундием, укажите функцию герундия и переведите это предложение.

5. В первом предложении четвертого абзаца укажите перевод союзного слова, присоединяющего придаточное предложение к главному.

6. Проанализируйте предпоследнее предложение последнего абзаца.

7. Выпишите из текста именные группы и переведите их.

8. Переведите текст с учетом выполненных заданий.

 

Text 4