Научно-технической литературы

Имени Н.Э. Баумана

 

 

Е. Н. ШИШКИНА, И. А. БЕЛОВА

МЕТОДИЧЕСКИЕ УКАЗАНИЯ

ПО ОБУЧЕНИЮ ЧТЕНИЮ

НАУЧНО-ТЕХНИЧЕСКОЙ ЛИТЕРАТУРЫ

НА АНГЛИЙСКОМ ЯЗЫКЕ ПО СПЕЦИАЛЬНОСТИ

«ПРИБОРЫ И СИСТЕМЫ ОРИЕНТАЦИИ,

СТАБИЛИЗАЦИИ И НАВИГАЦИИ»

ЧАСТЬ 1

 

Г. Москва

Г.

Рецензент к.т.н. Малахов А. А.

Б43	Шишкина Е.Н, Белова И.А. Методические указания по обучению чтению научно- технической литературы на английском языке по специальности «Приборы и системы ориентации, стабилизации и навигации». Часть 1. – М.: МГТУ им. Н.Э. Баумана, 2008. – 26 с., ил.

Содержат оригинальные тексты, знакомящие студентов с наиболее часто встречающейся терминологией по специальности, а также представляющие интерес с точки зрения грамматики – в них используются распространенные в технической литературе грамматические конструкции и обороты.

Предназначены для студентов младших курсов специальности «Приборы и системы ориентации, стабилизации и навигации».

УДК 541.01 Англ.

МГТУ им. Н. Э. Баумана, 2008

 

 

CONTENTS

UNIT 1. WHAT A GYRO IS
TEXT 1A. It All Starts with a Spinning Wheel
TEXT 1B. Base Motion Isolation TEXT 1C. Classification of Gyros
UNIT 2 How the gyro works
TEXT 2A. VECTORS AND SCALARS
TEXT 2B. Law of Gyroscopic Precession TEXT 2C. Accuracy
UNIT 3 Vertical Gyro Components
TEXT 3A. Gyro Motor or RotoR
TEXT 3B. What a directional gyro is
TEXT 3C. Flux Valve
SUPPLEMENTARY TEXTS FOR READING AND TRANSLATION
Text 1. Gyrocompass
Text 2. Uses for Vertical Gyros

Unit 1. WHAT A GYRO IS

Essential vocabulary

Axis,n - ось

Bearing,n – подшипник

Gimbal,n – карданная подвеска.

Gadget,n – приспособление, устройство

Pendulum bearing,n – качающийся подшипник

Pick-off,n –датчик преобразователь контролируемой величины

Attach, v – присоединять, прикреплять

Deviate, v – отклоняться, уклоняться

Spin, v (span, spun) – крутить, вращать

Support, v -поддерживать

 

Text 1A. It All Starts with a Spinning Wheel

Read the text and define the following terms:

spin motor; gimbals and outer gimbals; rotor bearings; ballbearings; gimbal axis.

Let us start with a spinning wheel called the rotor or spin motor. The wheel is usually kept spinning by electricity (it is really an electric motor). Occasionally, the rotor consists of little buckets on the rim and is spun by an air blast.

You might have played with a spinning toy (gyroscope) as a child, whose wheel was spun up by pulling a string. There are rotors which are spun up with clock-like springs, or with exploding cartridges.

The rotor is mounted (generally with ballbearings) in a configuration called gimbals. The ballbearings which support the rotor in the gimbal are called rotor bearings.

The outer gimbal is supported on the base surface with ballbearings—and the inner gimbal, which supports the rotor, is connected to the outer gimbal with ballbearings. These ballbearings on the gimbals are called gimbal bearings.

A few more definitions follow. The axis about which the rotor turns is called the spin axis. The axis about which the inner axis rotates is called the inner gimbal axis. Similarly, the axis about which the outer gimbal rotates is called the outer gimbal axis.

Finally, this entire configuration in which the rotor is mounted is some­times called a Cardan suspension—affectionately named after Jerome Cardan (1501-1576). History reports that Cardan could not figure out how to use the structure invented 300 years earlier by someone else. The complete instrument is called a gyroscope. Gyro is used interchangeably with gyroscope, although many times gyro is also used to refer to the spinning wheel or rotor.

Inner Gimbal Rotor Bearing

Outlet Gimbal

Inner Gimbal Axis

Gimbal Bearing Gimbal Bearing

Base Surface

Outlet Gimbal

Spinning Wheel or Rotor

 

 

Answer the following questions.

1. What is the heart of the gyro?

2. What are the basic parts of the gyro?

3. Do you happen to know anything about J.Cardan?

EXERCISES

 

EX. 1. Read and remember thefollowing nouns in singular and plural.

Axis –axes, analysis –analyses, datum –data, phenomenon –phenomena, radius –radii, stimulus –stimuli, nucleus –nuclei.

EX. 2. Translate the following words derived from a common root.

 

1. define – definite – indefinite – definition

2. circuit – circuitry

3. force – forcible – enforce – enforceable – unenforceable

4. exist – existence – existent – non-existent – co-exist –

co-existence

5. apply – applied – application – applicable – appliance

EX.3. Derive as many words as you can from the following words.

Continue, direct, magnetize, electrify, conduct.

EX.4. Define the functions of it, this, these, that, those, one in the following sentences. Translate them.

1. The components of the integrating gyro are quite similar to those used in the vertical, directional and rate gyros. 2. It is also possible to use a single rotor to establish the vertical. 3. It can only be said that the spin axis and the tilt axis lie in a plane established by the roll and pitch gyros. 4. The erection and centering control loops used for the pitch gyro are much the same as those described for the roll gyro. 5. It was stated earlier that the only part of this stable platform actually stabilized about three axes are the azimuth rotor and gimbal. 6. No one can trail a wheel behind a plane flying 8 to 10 mi up. 7. Studies indicate that an all-fluidic guidance and control system will solve this problem. 8. The advantage of the gas bearing gyro is that the rotor is protected from thermal and magnetic fields. 9. It is for this reason that all gyro compasses must be so suspended as to subject the gyro system to as little friction as possible about the vertical axis. 10. The rate gyro becomes sensitive to angular velocities about the two axes – instead of only one – and the output from the pickoff is in error. 11. One must know that a spinning liquid can be the basis for a gyroscope.

 

EX.5. Translate the following sentences, paying attention to the tense of the verbs.

 

1. Notice that we have been working with numbers of wide magnitude.

2. One of these meridians will pass through a small borough of London, England, called Greenwich. 3. It does affect a directional gyro. 4. If this directional gyro is being carried in an airplane there is another effect which must be considered. 5. On the surface of the earth, North South directions are measured in angles of latitude. 6.The measurement has been carried out with great accuracy.

 

EX.6. T ranslate the following sentences paying attention to modal verbs and different forms of the infinitive.

Must work

May be working

Might have worked

Can have been working

Could

1. The coil must have as many turns of wire as possible unless the current is heavy enough. 2. Listen. It must be raining outsides. 3. The experiment must have failed because someone made a mistake. 4. A powerful electromagnet may be constructed by placing a soft iron core inside the solenoid. 5. They may/might be going to increase airport fees to pay for increased security. 6. In late 18^th century Scotland you could be hanged for stealing a sheep. 7. These people might have a lot of money, but it doesn’t make them interesting.

 

EX.7. Translate the following sentences paying attention to the models:

1. If it happens…, I’ll be happy…

2. If it happened…, I would be happy….

3. If it had happened…, I would have been happy…

1.If an acid is mixed with a base, a chemical reaction occurs. 2. If you spin that plate of marbles, they will roll off the plate. 3. If a volcano erupted underneath the ocean, there would be a huge tidal wave. 4. If they agreed to make classes smaller, we could give each student more attention. 5. If the students had followed all the instructions, the experiment wouldn’t have failed. 6. The device would have been invented much earlier, if the scientists of that time had known the laws of physics and the properties of metals. 7. Had we known about these rules, we would have acted differently. 8. Suppose, that the same force were applied to a gyro. 9. If the gyro were sitting on a level table, the spin axis would be pointing up and down.

 

Exercises

EX. 1. Check yourself how you remember the words.

a) Translate the phrases:

To spin by pulling a string, to be mounted in, to be used interchangeably, is used to refer to, principal advantage, to point straight up, to determine how…, the gimbal pickoffs, the stabilized reference line, the base surface is rotated…, rate of change, angular position.

b) Finish the following sentences without looking into the text:

· The wheel is usually kept spinning…

· The rotor is mounted …..

· Cardan could not…

· If the stabilized reference line is horizontal….

· Degree of freedom is a common way…

 

EX.2. Summarize the subject matter of the texts (A and B) with the help of the following table.

GYRO CLASSIFICATIONS:

Single-Degree-Of-Freedom   DEGREES OF FREEDOM Two-Degree-Of-Freedom   Three-Degree-Of-Freedom   OR Instrument Gyro Transducer or Sensor USE Non-Instrument Gyro Direct Stabilization OR   Amount or Displacement WHAT IS MEASURED Rate or Angular Velocity

EX.3. Questions and problems to be revised.

1. Name three ways in which a gyro motor might be driven.

2. Name the principal parts of a gyroscope.

3. What is the chief advantage of a gyroscope?

4. Explain base motion isolation.

5. What does a pickoff on a gyro measure?

6. How can a gyroscope be used to demonstrate that the earth is rotating?

7. What are some of the different kinds of gyros?

8. What does degree-of -freedom mean with respect to gyros?

9. What is the degree-of-freedom of each of the following gyros: Vertical? Directional? Rate? Integrating?

Unit 2 How the gyro works.

 

Essential vocabulary

Angular veloсity,n - угловая скорость

Magnitude,n - величина, размеры.

Torque,n - момент кручения, скручивающее усилие

Thumb,n - большой палец руки.

Assume,v - принимать, предполагать, допускать

Advance,v - продвигаться, идти вперед.

Hitch-hike,v - путешествовать бесплатно

Wrap,v - обертывать, завертывать.

Counterclockwise -против движения часовой стрелки.

Conversely - обратно, наоборот

 

Text 2A. Vectors and Scalars

Read the text and define the following terms

vector; spin vector; scalar torque vector.

In order to answer this question, let us start with vectors. As you recall, a vector represents a physical quantity which has both magnitude(how much) and direction(which way). For example, the vector velocity has both magnitude (say 50 mi/hr) and direction (say North). By comparison, scalar quantity has only magnitude. Speed is a scalar quantity which has a magnitude (mi/hr) but does not have an associated direction.

Two factors are helpful in explaining the action of a gyro. First, there is the spin vector. The spin vector, an angular velocity, describes the way in which the gyro rotor rotates. The magnitude of the spin vector is measured in rad/sec, deg/sec, rev/min, etc.

The direction of the spin vector is found by wrapping the fingers of the right hand in the direction of spin rotation. Now, if the thumb assumes the usual hitch-hiking position, it points in the direction of the spin vector.

Consider the case where the spin motor is rotating counterclockwise when viewed from above. Wrapping the fingers of the right hand around the gyro in the direction of the spin, the thumb points up. Therefore, the spin vector points up. On the other hand, if the spin motor were rotating clockwise when viewed from above, the spin vector would point down.

THE RIGHT HAND SCREW RULE

This method of determining vector direction is known as the right hand screw rule. Imagine a wooden screw with a right hand thread—that is, where the thread spirals to the right from head to tip when viewed from the head end. The vector direction is the direction the screw would advance if the head were rotated in a clockwise direction when viewed from the head end.

Second, there is the torque vector. Torque is a force which tends to produce rotation or twisting. The magnitude of the torque is measured in dyne-centimeters, ounce-inches, pound-feet, etc. The amount of torque is found by multiplying the amount of force times the length which is the shortest distance between the force and what would be the axis of rotation. This shortest distance is called the moment arm. Assume that the force is 20 lbs and the moment arm is 4 ft long. Then the torque being exerted is 20 lbs 4 ft 80 lb-ft or

F* L =T

Where F= force, L= moment arm, and T= torque.

Torque being exerted= length.

 

EXERCISES

EX. 1. Translate the following words and define the meaning of their prefixes:

Disproportional, indifferent, impossible, to reheat, preheat, overload, to miscalculate, milliampere, to misunderstand, irregular, dissimilar, supercritical, undoubtedly, impractical, disproportional, misdirection, immeasurable.

 

EX.2. Form nouns from the following verbs, using various suffixes and translate them.

To utilize, to generate, to accelerate, to create, to apply, to classify.

 

EX.3. Find in the text the word turn, define its part of speech, then translate the following sentences, paying attention to the words in bold type.

1. One standard rate of turn for an airplane traveling about 300 m/hr is 3deg/sec. 2. Electric motors turn electrical energy into mechanical energy and mechanical energy in its turn may drive a generator to produce electrical energy. 2. When you turn the light on, you close the circuit and when you turn it off you open it. 3. Let’s turn our attention to the magnetic field of the earth. 4. It turns out that the planet “Venus” has no magnetic field. 5. Five turns of the coil will make the current turn through the coil five times. 6. Turn the page, please, it is you turn to read the article.

 

EX.4. Translate the following sentences, paying attention to the words in bold type.

1. Thus far we know that a gyroscope is something which tends to stay fixed in space. 2. Therefore, the longitude angle or the longitude of New York City is 74 deg. West. 3. So far we have examined in detail what a vertical gyro is. 4. However, if you travel along different latitude lines, the liner distance between equal angles of longitude will not be the same. 5. Similarly, at the Equator, the horizontal component of earth’s rate is 15 deg/hr×cos0 deg. 6. As long as the spin axis of the vertical gyro stays vertical – the vertical components of earth’s rate has no effect on a vertical gyro.

 

 

EX.5. Translate the following sentences paying attention to the difference in the meaning of ‘mean’ and ‘means’ as a verb and noun. In which sentence the verb can not be confused with the noun and why?

1. No mechanical means has yet been devised which controls the damping sufficiently without the use of a temperature controlled heating blanket. 2. This means that the cross-coupling error will be larger when an integrating gyro is used to measure rate. 3. In the toy gyroscope the rotation is affected by means of a piece of string. 4. This meant that the drift of the gyro had to be a small fraction of the Earth’s rate of rotation. 5. The resolution of the rate gyro means the minimum change in rate that the gyro can detect. 6. Any unbalance in the bridge means that the resistor is not at the calibrated value because the gyro is not at the correct temperature. 7. For very sophisticated systems means are employed to measure the rate-of-change of airspeed. 8. It is undesirable to have any outside means such as radar or star trackers provide information for such navigation systems.

 

EX 6. Look through the text once more and find participles I and II, define their function.

 

EX.7. Translate the following words.

1. измеряемый, измеренный, измеряя, измерив.

2. Создавая, создаваемый, создав, созданный.

3. Упомянутый, упоминая, упомянув, упоминаемый.

4. Существующий, существовавший, существуя.

EX.8. Translate the following sentences, paying attention to the forms and functions of the participle.

1. When subjected to a torque the gyro will move in a predictable fashion. 2. The earth’s vertical is a line passing through the surface of the earth and the center of the earth. 3. Using trigonometry, we find the horizontal component of earth’s rate. 4. This means that this effect called apparent drift will always appear as a tilt from the vertical about the gyro axis aligned with the pitch axis of the aircraft. 5. Being rubbed, some substances become electrified.6.Having examined the properties of the gyro, lets discuss its construction. 7. Working at his new device, the inventor made a number of improvements, the latter resulting from his own experiments.

Text 2C. Accuracy

Read and translate the following extract and answer the question.

1.What are the reasons of vertical errors?

2. Define a) random drift;

b) apparent drift.

Accuracy of the vertical must be a consideration. Vertical gyros are needed because we want an accurate reference line in space — and that line must be along the vertical. Any difference between the line and the vertical might cause errors somewhere in the systems referenced to the gyroscope.

There are at least three effects causing vertical error, and the amount of error depends upon the kind of erection control and the erection rate. There are: drift, acceleration and aircraft turns.

Drift errors are both random and apparent. Remember, random drift occurs because the gyro is not a perfect instrument. Apparent drift occurs because a gyro is fixed in space — not fixed relative to the earth. Suppose we have a gyro with a random drift: of 30 deg/hr. That is 0.5 deg/min. Added to this is the apparent drift due to earth's rate: a maximum of 15 deg/hr or 1/4 deg/min. Finally, if the gyro is in an airplane, there is an additional apparent drift due to earth's profile. If the plane is travelling at 300 mi/hr, the apparent drift is about 4.3 deg/hr or 0.07 deg/min. Therefore, the maximum drift would be 0.5 deg/min plus 0.25 deg/min plus 0.07 deg/min or 0.82 deg/min.

Exercises

EX.1. Find in the texts English equivalents for the following words and groups of words.

Как вы помните, во-первых, теперь, теперь когда, итак, поэтому, с другой стороны, во-вторых, поскольку.

 

EX.2. Read these abbreviations and units.

Oz- sq-in/sec means...

Oz-in-sec means...

Deg/min means …

Rad/sec means...

Rev/min means...

Oz-in means...

Lb-ft means …

Gm-cm means …

 

EX.3. Finish the following sentences without looking in the texts:

a) Torque is a force…..

b) Vector represents a physical …..

c) The greater the angular momentum …..

d) Drift errors are both…..

 

EX. 4. Define the terms:

a) inertia

b) precession

c) moment arm

 

QUESTIONS AND PROBLEMS

1. What is the difference between a scalar and a vector?

2. What is the right hand screw rule?

3. A man pulls against a 2 ft crowbar with a 60 Ib force.
How much torque does he exert?

4. What is the law of gyroscopic precession?

5. State the law of gyroscopics.

6. Just what is precession?

7. Draw a sketch showing a gyro with torques applied.

8. Show how the right hand can be used for finding precession.

 

Questions to the text.

1. Why is the rotor always circular?

2. What does the gyro performance depend upon?

EXERCISES

EX.1. Mind the difference and translate the following words.

Later-latter-letter; through- though; then-than; so-so far; but-but for; this-thus.

 

EX.2. Find in the text the comparative construction, then translate the

following expressions:

Чем больше, тем лучше; чем быстрее, тем хуже; чем выше, тем сильнее; чем ближе, тем теплее; чем тоньше, тем ниже.

 

EX.3. Translate the sentences, paying attention to the words in bold type.

1. The faster an object moves, the greater is the resistance.2. The larger the diameter of the rotor, the less the inertia is. 3. The smaller the resistance, the more current will flow through the wire. 4. For any particular fluid the faster gimbal rotates, the more the fluid resists the motion. 5. The greater the density of fluid, the heavier a body for a given size can be floated. 6. The more pressure applied, the higher the friction level. The higher the friction level, the shorter the life. 7. The larger the projectile, or the faster the spin, the less is the precession.

 

EX.4. Find in the text the emphatic construction, then translate the following sentences:

1. It is the extremely high stability of the gyro that attracts the scientists’ attention. 2. It is the fuel cell that is the promising power source for the future. 3. It is in space flights that the fuel cells have been proved reliable in operation.4. It was Foucault who noticed this property of the spinning wheel.

 

EX.5. a)Find the gerunds in text 3A and define their functions.

b) Translate the following sentences.

1. Here are some general rules for manipulating exponents. 2. By working with the powers of 10 it is easier to keep track of the numbers. 3. We start out by making the spin axis point along the earth’s vertical. 4. After flying 6 hrs, the gyro spin axis would be tilted around the pitch axis about 26 deg. from the vertical. 5. Before accomplishing the precession the switch must close. 6. Semilinear system does a much better job of permitting the gyro to remember the average position of the pendulum than does the bang-bang system.7.One cannot use this instrument without its being regulated.8.We know of Foucault’s having made his discovery at the end of the 18 century.

 

Ex.6. a) Find in the text the word time, define its part of speech.

b) Translate the sentences.

1. There was а time when people knew nothing about flying.2.One of the spheres is four times as large as the other one.3.Four times four is sixteen.4. At times a spark appeared between the two ends of the wire. 5. The experiment at question was finished in good time. 6. In those times lightning was a subject for legends. 7. What time is it? I think it’s time to stop the motor.

 

Text 3 C. Flux Valve

Read the text and then explain what a flux valve is.

The directional gyro has the same random drift problems common to the vertical gyro. Even originally pointed North, random torques due to pickoff friction, mechanical unbalance, etc., would cause the gyro to precess in an unpredictable fashion.

Therefore, we must have a control system which would keep the spin axis of the directional gyro always pointing North. Why not use a compass as a reference, as we used the pendulum for the vertical gyro? Basically, that is what is done, except that is difficult to hook up a position pickoff to compass needle. The forces available are so small that most any measuring device foul up compass performance. Instead, we hang a flux valve in the earth’s magnetic field. A flux valve is much like a synchro. In the synchro, a particular set of voltages is set upon the three stator winding – depending upon the orientation of the rotor with respect to the stator. In the flux valve, a particular set of voltages are set up in the three stator windings – depending upon the orientation of the flux valve with respect to magnetic North. In the synchro, the voltages are induced from the rotor. In the flux valve, the voltage is induced by the earth’s magnetic field. There is nothing in the flux valve equivalent to the rotor of a synchro.

 

EXERCISES

EX.1. Translate the following word combinations without consulting the dictionary.

Straight and level flight; meridian lines converge at North and South; curve in space; vertical component of earths rate equals earth’s rate times sine latitude; drift relative to meridian line; flux valves sense earths magnetic field.

 

EX.2. Define the following words:

1) artificial horizon;

2) figure of merit;

3) follow up system.

 

EX.3. Questions and problem s.

1. What are two characteristics of gyro motors?
2. Explain the nature of apparent drift in directional gyros.
3. Explain why directional gyro can be compared with magnetic compass.
4. Why cant a compass be used as a heading reference?
5. What is the effect of the horizontal component of earth‘s rate on a directional gyro?
6. What are the uses for vertical gyro?

 

Text 1. Gyrocompass

North reference for the directional gyro came from the earth’s magnetic field. It is also possible to build a directional gyro in such a way that the earth’s rotation causes the spin axis to seek North.

It works like this. Suppose we take a directional gyro and make the rotor bottom heavy by adding a weight on it. As long as the spin axis is horizontal, the added weight has no effect. But suppose that the spin axis dips. This moves the weightup, which in turn causes a torque about the tilt axis. With the spin direction indicated, the torque would cause the north end of the spin axis to precess off in an Easterly direction. In the same way, if the spin axis rises, the resulting torque from the displacement would cause the North end of the spin axis to precess in a westerly direction. The bottom – heavy rotor is pendulous, and the indicated precession arises from this pendulosity.

Next, let’s locate this pendulous DG at some latitude. Remember that there is a horizontal component of earth’s angular velocity which is equal to earth’s rate(15deg/hr) times cosine latitude. This vector is in the horizontal plane and points North. As long as the DG spin axis is also pointing North, this vector exerts no influence on the DG.

Suppose that the spin axis drifts off to the East, then the horizontal component of earth’s rate can be resolved into two components: One along the gyro spin axis (which does not effect the operation), and one along the tilt axis. A component of the angular velocity about the tilt axis means that the gyro tilt axis (stabilized in space) is moving relative to the earth. In effect, the North end of the gyro tilt axis is rising from the horizontal plane. Because of the pendulosity, the gyro will precess in a westerly direction if the spin axis is raised- and that precession in a westerly direction will get the spin axis pointing North again.

In the same way, if the gyro points West, a component of earth’s rate is developed which is the same as the spin axis dipping, and easterly precession results. Thus, this gyro seeks North due to the earth’s rotation, just as a compass seeks magnetic North, due to the earth’s magnetic field. In fact gadgets constructed along these lines are called gyrocompasses.

The gyro compass will only work satisfactory in slow moving vehicles. Therefore, they are not suitable for aircraft, but are used extensively on boats.

Имени Н.Э. Баумана

 

 

Е. Н. ШИШКИНА, И. А. БЕЛОВА

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