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Preface

We have compiled the following materials for the undergraduates, advanced and postgraduates both in Radio Physics and Information Technologies. The updated version will help you keep on your toes in English studies thanks to its authentic data and modern methodology content training all together reading, writing and speaking skills on the broad scientific basis. An insight into lexis and word formation will hopefully give you a push forward in workshops and conferences communication.

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Unit 1

1. Read the following international words and translate them without a dictionary:

Laser, photon, opposite, radiate, generate, generator, sphere, electron, quartz, emission

2. Read and learn the following key words, be able to use them in speech:

current – ; reflect – ;

absorb – ;

agitate – , , ; emit – ;

avalanche – ; collide – ; ether – ;

ethereal – ; irradiation – , ; irradiate – ;

axis (axes, pl) – .

3. Form nouns of the following verbs:

emit, collide, irradiate, agitate, radiate, absorb, reflect, compress, contain, generate, occur, form, increase, decrease

Reading

1. Make one text putting the paragraphs A–E into the correct order from 1–5.

Principle work of lasers

A.A part of the photons moving along the tube in two directions hit the mirrors from which they are reflected into the opposite direction. A low-density ether path is formed along the tube due to the multiple passages of photons. This path is compressed by the more condensed ether which enters through the wall of the tube from outside.

B.Most of the emitted photons hit the wall of the tube where they are either absorbed or go outside. But if the most part of a tube is covered with material and has only a window for irradiation by the light, then almost all photons will be reflected from the tube inside and again to be absorbed and radiated by atoms.

C.But gas lasers are usually made of long round tubes which contain gases through which runs independent electric current from a high frequency generator. When

electric current passes through a gas, the tangential (non-elastic) collisions of

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electrons with the gas atoms nuclei occur. Upon these collisions the ethereal spheres of nuclei emit photons.

D.Since the other pressure across the tube is higher than that along the tube, then the ethereal sphere of nuclei is being elongated in direction parallel to the axis of the tube. Upon the colliding of these nuclei with orbital electrons from the nuclei occurs emission of photons in the direction parallel to the axis of the tube. Thus, the avalanche-like nuclei agitation as well as photon emission in either mirrors direction form. Part of the emitted photons leave outside. Thus the unidirectional emission of photons from the laser is formed.

E.Inside of a glass or quartz tube there is a gas which is irradiated by light. If photons have suitable energy they at collision with gas are absorbed by the ethereal sphere of nucleus due to that the ethereal sphere is increasing. This radiation of photons occurs in different sides. Photons can be absorbed by other nucleuses and the second at collisions with orbital electrons can radiate again the photons.

2.Read the text. For items 1–7 match the ending of each sentence A–F to its beginning. There is one extra ending you do not need to use.

Not only gases can be taken as working bodies of lasers, A___________. Herewith the atoms of the active elements must B___________. The density of a photon beam characterizes its force, but the force and the value of cross-section of the beam characterize the power of the beam. The force of a laser beam also depends

C___________.

Solid lasers could be more powerful than the gas and liquid lasers, since in solid photons have low velocities of motion only when they leave the laser, photons increase their velocity to the limit. Due to that the photon beam inside the laser and upon leaving it may have high density D___________.

In the laser is formed a ray with small divergence because if increase the frequency of photons passing from a mirror to a mirror then the pressure of the ether is decreasing along the tube E_____________. Due to that the ethereal sphere of the nucleuses is extended in the direction of the axis of the tube F____________.

1.and across the tube remains former;

2.which will not destroy the laser;

3.but also solids and liquids;

4.and the radiation of photons occurs also mainly in the axis of the tube;

5.on frequency of radiated photons, the more frequency the more force;

6.be agitated due to the action of extraneous photons used for the excitation of atoms;

7.since the beam will destroy the mirrors reflecting the photons.

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3.For questions 1–10 read the text and decide whether the information in the sentences is RIGHT or WRONG. Write the correct letter (R/W).

Applications

Red HeNe lasers have many industrial and scientific uses. They are widely used in laboratory demonstrations in the field of optics in view of their relatively low cost and ease of operation compared to other visible lasers producing beams of similar quality in terms of spatial coherence and long coherence length (however since about 1990 semiconductor lasers have offered a lower cost alternative for many such applications). A consumer application of the red HeNe laser is the Laser Disk player, made by Pioneer. The laser is used in the device to read the optical disk.

The twentieth century was characterized by the harnessing of electrical energy to create broad economic and societal benefits. Examples of developments enabled by electricity include transport, heating, lighting and the recent explosive expansion of information and communication technologies. Looking to the future, innovative applications of energy in the form of light have the potential to shape the twenty-first century.

Some forty years ago, the principle of light amplification by stimulated emission of radiation (giving the acronym laser) was first postulated and since then lasers have matured into reliable and efficient industrial tools. Typical applications include cleaning of artwork and buildings, surgery, automotive manufacturing and shipbuilding. The present paper considers the use of lasers as manufacturing tools.

1.Red HeNe lasers have few industrial and scientific uses.

2.Red HeNe lasers have problems in operation.

3.Since about 1990 semiconductor lasers have offered a lower cost alternative for many applications.

4.The twentieth century was characterized by the development of electrical energy.

5.Early developments were enabled by electricity include transport, heating, lighting.

6.Innovative applications of energy in the form of light have no progress to shape the twenty-first century.

7.Since 70-s lasers have matured into reliable and efficient industrial tools.

8.The principle of light dispersion was first introduced some forty years ago.

9.The article considers the use of lasers as manufacturing tools.

10.Typical applications include artwork cleaning, surgery, automotive manufacturing and shipbuilding.

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Grammar and Word Formation

1. Open the brackets. Put in the correct verb form.

The first HeNe lasers 1.____ (emit) light at 1.15 µm in the infrared spectrum and 2.______ (be) the first gas lasers. However, a laser that operated at visible wavelength 3.______ (be) much more in demand, and a number of other neon transitions 4._____ (investigate) to identify ones in which a population inversion can be achieved. The 633 nm line 5.________ (find) to have the highest gain in the visible spectrum, 6._________ (make) this the wavelength of choice for most HeNe lasers. However other visible as well as infrared lasing wavelengths 7.______ (be) possible, and by 8.______ (use) mirror coatings with their peak reflectance at these other wavelengths, HeNe lasers 9.________ (can) be engineered to employ those transitions; this 10.__________ (include) visible lasers appearing red, orange, yellow and green.

2. Insert the correct word form.

Laser direct metal deposition

For high value applications such as aero engine components it is generally economically _______ (attract) to repair worn or locally damaged parts rather than

_______ (place) them. A candidate repair technology is laser direct metal deposition (DLMD) in which a laser is used to melt powder onto a substrate material. In contrast to approaches in which the powder is placed on the substrate, the powder is fed via a nozzle into the laser spot on the substrate, as illustrated in Fig.8. This results in the

______ (form) of a _______ (melt) pool which, on cooling, leaves a solid deposit of the powder material on the substrate.

Laser deposition has two main advantages over other powder deposition techniques. _______ (First), the operation is a low heat input process which reduces the likelihood of liquation cracking. Secondly, the use of very small spot sizes enables highly accurate and reproducible deposits to be made. Additionally,

__________ (adaptation) control systems have been developed that monitor the characteristics of the molten pool and adjust the process as necessary to maintain deposit quality. Figure 9 shows a multiplayer deposit in an aero engine alloy.

In addition to repair, however, direct laser metal _______ (deposit) is suitable for

_______ (origin) part build. By _______ (vary) powder composition as a part is built up, a _______ (functional) graded component can be developed with particular performance characteristics directly related to position. The process can also be used for rapid prototyping.

For the process to gain widespread acceptability, however, development is required to increase deposition rates, deposition _______ (efficient) and to establish appropriate processing parameters for high _______ (accurate) and quality.

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3. Choose the necessary word.

All manufacturers are 1._____ striving to gain a competitive edge over their rivals and the advantages and disadvantages of each manufacturing route are thoroughly evaluated before production begins. Fabrication or 2._____ with lasers offers several potential benefits:

•3._____ productivity – more rapid part manufacture at reduced cost.

•Improved quality – for example, minimal distortion and hence 4._____ levels of rework.

•Enhanced performance – this can be seen by longer lifetimes or greater resistance to corrosion or high temperature. 5._____ , laser repair technologies can give rise to significant life extensions of otherwise exhausted components.

•Novel fabrication routes and components – where 6._____ technologies simply

are not available.

The choice of manufacturing route, however, is 7._____, an economic one. 8._____, there is a continuous battle between manufacturing technologies to gain a competitive edge that is closely analogous to the competition between individual manufacturers.

To respond to this challenge, developments in laser materials processing are being made to address the 9.______ of current technology and maximize potential. The present paper describes, somewhat selectively, developments and opportunities for manufacturing with lasers in three 10.______ themes.

Writing

Imagine that you are going to take part in the conference. Write an e-mail to your colleague. (100 words)

1.Ask 5 questions on the topic Lasers.

2.Develop the topic Lasers. Advantages and Disadvantages.

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Unit 2

Read and memorize the following words:

–artificial – ;

–application – , ;

–consistent – , ;

–sine wave – ;

–adjust – ;

–to be of importance – ;

–permeability – ;

–permittivity – .

Reading

1. Make one text putting the paragraphs A–E into the correct order from 1–5.

Radio wave

A.The wavelength is the distance from one peak of magnetic flux to the next, and is inversely proportional to the frequency. The distance a radio wave travels in

299.8 meters.

B.Radio waves were first predicted by mathematical work done in 1867 by James Clerk Maxwell. He noticed wave like properties of light and similarities in electrical and magnetic observations. He then proposed equations that described light waves and radio waves as waves of electromagnetism that travel in space, radiated by a charged particle as it undergoes acceleration. In 1887, Heinrich Hertz demonstrated the reality of Maxwell’s electromagnetic waves by experimentally generating radio waves in his laboratory. Many inventions followed, making the use of radio waves to transfer information through space.

C.Radio waves are a type of electromagnetic radiation with wavelengths in the electromagnetic spectrum longer than infrared light. Radio waves have frequencies from 300 GHz to as low as 3 kHz, and corresponding wavelengths ranging from 1 millimeter to 100 kilometers. Like all other electromagnetic waves, they travel at the speed of light. Naturally occurring radio waves are made by lightning, or by astronomical objects. Artificially generated radio waves are used for fixed and mobile radio communication, broadcasting, radar and other navigation systems, communication satellites, computer networks and innumerable other applications. Different frequencies of radio waves have different propagation characteristics in the Earth’s atmosphere; long waves may cover a part of the Earth very consistently, shorter waves can reflect of the ionosphere and travel around the world, and much shorter wavelengths bend or reflect very little and travel on a line of sight.

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