3. Give adequate Russian equivalents of the italicized words.
Assume – общий элемент смысла: принятие принципа, предположения (часто без доказательств),
формы, обязательства, власти и т.д. Частотные русские эквиваленты: to assume – допускать,
предполагать, принимать, приобретать (характер, форму); assumption – допущение, предположение.
1. The distribution of Species within an area assumes a definite pattern. 2. They assumed the process to occur within a wide range of temperatures. 3. Historians assumed that calendars had come into being with the advent of agriculture. 4. It is reasonable to assume that reading begins with the perception of graphic stimuli. 5. In 1905 a young man of 25 brought a paper to the German journal “The Annals of Physics”, which was published under the unassuming name “On the Electrodynamics of Moving Particles”. 6. Under
the simultaneous action of pressure and stress the resulting sample assumes predicted shape.
Point – общий элемент смысла: сосредоточенность (сгусток) в пространстве, времени, изложении. Частотные русские эквиваленты: point (N) – точка; место; момент; пункт; суть; смысл и т.д.; to point – указывать, показывать, свидетельствовать и т.д.; a case in point – рассматриваемый случай.
1. The lecturer was speaking on the spread of writing over the earth from its points of origin in Egypt, Mesopotamia and China. His main point that writing had come to Europe from the East was not original and left the audience indifferent. But among other things he brought up two points which aroused his listeners. He pointed to the similarity of alphabets of related languages and tried to seek an explanation from the point of view of general linguistics. Up to this point the lecture had been merely dull. Now it was misleading as well. I was on the point of leaving the room when someone said aloud. “Your last remark was not to the point, Professor, or else I don’t see the point” 2. The bacteria level of the Potomac River has been reduced to the point where much of the river would be swimmable. 3. Much of what we do in space, much of what is expected of us, strains our technology to the breaking point. 4. Today, atomic power could support space vehicles on journeys of several years duration, but the cost at this point is still prohibitive for practical use. 5. Everything points to your being wrong. 6. If there were any flaws in their arguments they would be pointed out to them immediately.
4. Read and translate the text.
POLYPHASE SYNCHRONOUS MOTOR
Since a dc shunt motor is electrically and magnetically identical with a shunt generator, the shunt dynamo may be operated either as a motor or a generator, with only minor changes in the voltage ratings. In the same sense we should expect that the alternator may also be operated as an ac motor when electrical rather than mechanical energy is supplied to it. If the mechanical power supplied to a rotating alternator is removed while the dc field remains energized, and an ac supply is then connected across the armature terminals, torque will be developed and the alternator will continue to rotate at a speed determined by the frequency of the ac supply. Changes in mechanical load within the machine’s rating will not cause a change in speed, and we thus have a synchronous motor.
Construction. Essentially, the construction of a polyphase synchronous motor is the same as that of a synchronous alternator. In large machines, the armature is on the stator and is wound for the same number of poles as the rotor. Some smaller polyphase motors have rotating armatures, but this is rare. As with an alternator, a dc generator may be mounted on the motor shaft to excite the field, although synchronous motors, both single and polyphase, which require no dc excitation, are also manufactured today. In the most common type of field construction, the poles are somewhat different from those of the alternator. In addition to the exciting winding, a synchronous motor often has a squirrel-cage winding in the rotor. The slots of this winding are in the pole faces and are parallel to the shaft. The ends of the copper bars embedded in the slots are short-circuited in the same manner as in a squirrel-cage induction motor. This short-circuited winding on the rotor is known as the cage winding, the damper winding, the amortisseur winding, or sometimes, to describe its function, the starting winding.
Since the armature is wound in the same manner as that for an alternator, it is, of course, identical with the stator of a polyphase induction motor as well. With three-phase voltage applied to the armature, a rotating field of constant magnitude is therefore produced. The speed of the field, which is synchronous speed, depends upon the frequency of the supply voltage and the number of poles for which the armature is wound. A typical polyphase-synchronous-motor-rotor is shown in Fig 1.
