Учебник английского языка для технических университетов и вузов Издание шестое, стереотипное
 Скачать 1.44 Mb.
|
|
To be read after Lesson 9 Getting into Deep Water The dark depths of the Gulf of Mexico, once frequented by only the sea creatures, are now alive with human activity. Miniature submarines and robot-like vehicles move around the ocean bottom while divers make their way around incredible underwater struc tures — taller than New York City skyscrapers, but almost totally beneath the surface of the waves. Modern-day explorers are using technology worth of Jules Verne and Jacques Cousteau to find fresh supplies of oil and natural gas. Until recently, drilling in the Gulf was concentrated close to shore in water as deep as 9 m. But now the scientists are looking to hundreds of meters deep and 160 km and more from land. The deep water research began in 1984. Since then many Ame rican companies have built the world’s deepest production plat forms of more than 100 storeys high. Finding gas and oil deposits at large depth is not an easy technological task. Voyage to the Bottom of the Sea There is an American project of one-person submarine, which will «fly» to the bottom on inverted wings rather than simply sink ing under its own weight as the bathyscaphes did. This design is more like an aeroplane than a balloon. It could one day make ex ploring the ocean depth as easy as flying a plane is today. The most difficult problem is to find a material that is also light enough to allow the craft to float back to the surface if there is a loss of power or some other emergency. Alumina, a hard ceramic, was chosen for the vessel. The pilot’s capsule is about a meter in diameter, 5 centimeters thick and about 2 meters long. It is capped at one end with a ce ramic hemisphere and at the other with a glass viewing dome. The rest of the craft, including the wings on either side and the casing at the rear for the motors, are made of a lightweight composite material. In addition to the pilot, the pressure vessel houses the controls and instrument panel, the life-support system and a 24-volt power supply. The pilot effectively operates the craft by radio control. The batteries feed a pair of electric motors that can drive the craft at up to 14 knots (25 kilometers per hour). The craft could dive vertically but this would be uncomfortable for the pilot who lies face downwards in the cylindrical chamber. So it descends at an angle of up to 45°. «Deep Flight» is designed to be as stream lined as possible. This means making the submarine’s cross section as small as possible and providing as little equipment as possible on the hull. At a cruising speed of 10 knots «Deep Flight» will descend at a rate of 200 meters per minute and reach 11,000 meters in about an hour in the Mariana Trench (Марианская впадина), the deepest site on Earth. The weight of the craft is 2.5 tonnes, which is about the same as a large car. This will allow it to be launched from any vessel. To be read after Lesson 10 Laser Technology In the last decade there was outstanding progress in the devel opment of laser technology and its application in science, industry and commerce. Laser cutting, welding and machining are begin ning to be big business. The market for laser systems represents around 2.5 % of the world machine tool market. Which country is the biggest producer and consumer of lasers? Why, Japan, naturally: Japan produced 46 % of world’s lasers in 1989, while figures for Europe and the USA are 32 % and 22 %. Ja pan is building 1,200 to 2,000 CO2 lasers per year of which some 95 % are over 500 W power and 80 % of them are used for cutting operations. Europe is the second largest user and the third largest producer. In 1990 Europe’s market for lasers was $128 million, of which Germany consumed about $51 million, and Italy — $12 million. The Germany met 90 % of its demands through domestic produc ers. Growth rate of the European market is estimated at 10 to 15 % per year. In the future the main trend influencing the industry will be la ser source prices. The prices are dropping. There appear lasers of modular construction. The complexity of laser machines is rising. Multi-axes systems are in more use now. Recently a 7-axis CNC la ser machining center has been introduced. In addition to X,Y and Z axes, there are two rotary axes, A and C, and two more linear axes, U and V, to give a trepanning (прорезать большие отвер стия) motion to the laser. Optical Disks and Drives Optical disks can store information at much higher densities than magnetic disks. Thus, they are ideal for multimedia applica tions where images, animation and sound occupy a lot of disk space. Besides, they are not affected by magnetic fields. This means that they are secure and stable, e.g. they can be transported through airport metal detectors without damaging the data. However, opti cal drives are slower than hard disks. While there are hard drives with an average access time of 8 milliseconds (ms), most CD-ROM drives have an access time of 150 to 20 ms. There are various types of optical drives, which have become a reality. CD-ROM systems use optical technology. The data is re trieved using a laser beam. To read CD-ROM disks, you need an optical drive (a CD-ROM player). A typical CD-ROM disk can hold 650 MB (megabytes) of sound, text, photographs, music, mul timedia materials and applications. In addition, most CD-ROM drives can be used to play audio CDs. Do you remember that CD stands for compact disk? Yet CD-ROM technology has one disadvantage. The data on a CD-ОМ cannot be changed or «written» to, i.e. it is impossible to add your own material to what is on the disk. It is like a music CD. It is not designed for you to write on, it is designed to hold a lot of information that the user doesn’t need to change. Magneto-optical (MO) drives use both a laser and an electro magnet to record information. Consequently, MO disks are rewritable, that is they can be written to, erased, and than written again. They are available in two formats. Their capacity may be more than 2 GB (gigabyte) or 230 to 640 MB. Such combined de vices are good for back up purposes and storage of large amounts of information such as a dictionary or encyclopaedia. To be read after Lesson 11 Space Cooling A new method of cooling that can generate cryogenic tempera tures of 200 °C below zero without the use of electricity and with almost no moving parts has been tested at the Jet Propulsion Labo ratory in Pasadena, California. The refrigerator used for the pur pose was recently tested to — 253 °C, only 20 degrees above absolute zero, the lowest possible temperature. In space such cooling system could increase the life of future space station refuelling ports by cooling the large liquid-hydrogen fuel tanks which are likely to be in service. In future earth applications it could be used for cooling hydro gen-powered cars and planes, as well as for cooling superconduct ing motors and computers. According to the JPL (Jet Propulsion Laboratory) experts the key lies in the use of hydrides, materials that interact with hydro gen. These materials absorb tremendous amounts of hydrogen gas at room temperature. The engineers of the JPL have taken advan tage of this property to build a series of devices that act as compres sors and provide a continuous cooling stream of liquid hydrogen. The system saves weight in space since it can use direct solar heat instead of electricity from heavier, inefficient electric systems. Because it has so few moving parts and uses the same supply of gas in a closed cycle, it could operate for many decades. Because of its long potential lifetime, the system could be used to cool infrared sensors during missions to the other planets, which may take 10 years or more to complete. The Propulsion Challenge1 Magsails are a form of solar sails that use a completely different type of physical interaction with the Sun. Magsail is a simple loop (петля, контур) of high-temperature superconducting wire carry ing a persistent2 current. The charged particles in the solar wind are deflected3 by the magnetic field, producing thrust. Although the thrust density in the solar ion wind flux is 5,000 times less than the thrust density in the solar photon flux4, the mass of a solar sail goes directly with the area, whereas the mass of the magsail rises with the perimeter of the enclosed area. The effective cross-sectional area of the magnetic field around the magsail is about a hundred times the physical area of the loop. As a result, preliminary calculations show the thrust-to-weight ra tio of a magsail can be an order of magnitude (порядок величины) better than a solar sail. Recent thermal balance calculations indi cate that a properly Sun-shielded5 cable can be passively main tained at a temperature of 65 К in space, well below the supercon ducting transition point for many of the new high temperature su perconductors. Notes to the Text
Computer Graphics Computer graphics are known to be pictures and drawings pro duced by computers. A graphics program interprets the input pro vided by the user and transports it into images that can be displayed on the screen, printed on paper or transferred to microfilm. In the process the computer uses hundreds of mathematical formulas to convert the bits of data into precise shapes and colours. Graphics can be developed for a variety of uses including illustrations, archi tectural designs and detailed engineering drawings. Mechanical engineering uses sophisticated programs for appli cations in computer-aided design (CAD) and computer-aided manufacturing (CAM). In the car industry CAD software is used to develop, model and test car designs before the actual parts are made. This can save a lot of time and money. Basically, computer graphics help users to understand complex information quickly by presenting it in more understandable and clearer visual forms. Electric engineers use computer graphics for designing circuits and in business it is possible to present informa tion as graphics and diagrams. These are certain to be much more effective ways of communicating than lists of figures or long expla nations. Today, three-dimensional graphics along with colour and com puter animation are supposed to be essential for graphic design, computer-aided engineering (CAE) and academic research. Com puter animation is the process of creating objects and pictures which move across the screen; it is used by scientists and engineers to analyze problems. With appropriate software they can study the structure of objects and how it is affected by particular changes. A graphic package is the software that enables the user to draw and manipulate objects on a computer. Each graphic package has its own facilities, as well as a wide range of basic drawing and paint ing tools. The collection of tools in a package is known as a palette. The basic geometric shapes, such as lines between two points, arcs, circles, polygons, ellipses and even text, making graphical objects are called «primitives». You can choose both the primitive you want and where it should go on the screen. Moreover, you can specify the «attributes» of each primitive, e.g., its colour, line type and so on. The various tools in a palette usually appear together as pop-up icons in a menu. To use one you can activate it by clicking on it. After specifying the primitives and their attributes you must transform them. Transformation means moving or manipulating the object by translating, rotating and scaling the object. Translation is moving an object along an axis to somewhere else in the viewing area. Rotation is turning the object larger or smaller in any of the horizontal, vertical or depth direction (corresponding to the x, у and z axis). The term «rendering» describes the tech niques used to make your object look real. Rendering includes hid den surface removal, light sources and reflections. To be read after Lesson 12 The Space Age Russia was the first nation into space and is recognized as the world’s leader in building space stations and conducting long- duration space missions. Since Yury Gagarin’s epic flight Russian space science and engineering have come a long way. Space tech nology remains Russia’s deepest source of pride (гордость). Russia has launched a great number of space vehicles designed to perform a variety of functions. Unmanned satellites have been of great sig nificance in the exploration and peaceful use of outer space. They help us learn more about the relations between processes occurring on the sun and near the earth and study the structure of the upper atmosphere. These satellites are provided with scientific equipment for space navigation of civil aviation and ships, as well as explora tion of the World Ocean, the earth’s surface and its natural re sources. In April 1971, history’s first space station, Salyut 1, was launched and over the next 15 years six its subsequent versions op erated in space. Many orbital manned flights were performed aboard these stations involving a lot of cosmonauts, most of them having flown several times. Russian cosmonauts are known to hold the record for the longest time in space (L. Kizim has worked 375 days) and for continuous stay in space (V. Titov and M. Manarov — 365 days, i.e. a year). The knowledge of Russian doctors and re searchers about the medical and psychological consequences of longterm space flight far exceed that of American scientists. In 1973, two years after Salyut 1, the United States launched Skylab, the Western World’s first space station which was used for three highly successful missions. All these manned missions paved the way for even longer stays aboard the Russian Mir space station and, then, aboard the International Space Station. The most successful Mir space station was launched in Febru ary 1986. It was expected to have a lifetime of only five years but it had been in orbit for 15 years before its controlled re-entry into the atmosphere. This space station was equipped with an astronomical observatory module named Kwant. It incorporated all the novelty that could be offered by designers and engineers. To keep produc tivity high, Russian designers paid much attention to the space sta tion livability. The interior of Mir was painted in two colours to provide the crew with a sense of floor and ceiling. On Mir cosmo nauts got two days off each week and had a special radio so that they could talk to their families and with any sportsman, scientist or celebrity they wanted. With the twin Vega space probes being successfully launched in 1986, Russian scientists conducted close-range studies of Hailey’s comet and gathered impressive scientific data about Venus. Vega 1 and Vega 2 carrying more than 30 research instruments passed within 10,000 kilometers of the comet’s heart, transmitted high- quality pictures to Earth and revealed for the first time the dimen sions and dynamics of its ten-mile-long nucleus. The relative speed of approaching the comet was equal to 78 km/sec. It should be pointed out that the study of Hailey’s comet was conducted on the basis of extensive cooperation of scientists. Scientists from nine countries, including the U.S, joined the Vega project. When the 170-million horse power launch vehicle called «Energia» was successfully tested in 1987, Russia has gone far ahead of the United States in the space race. With the new multi-purpose Energia rocket it became possible to put into orbit a 100-ton payload (one must know that the first satellite carried 83,6 kg). The first International Space Station components, Zarya and Unity, have opened a new era of space exploration. The three-stage Russian Proton booster was used to launch the Zarya module. The rocket was designed by the Salyut Design Bureau and is manufac tured by the Khrunichev State Research and Production Space Centre in Moscow. The Proton is among the most reliable heavy-lift launch vehicles in operation with its reliability rating about 98 per cent. Proton measures about 180 feet tall, 24 feet in diameter at its widest point and weighs about 1,540,000 pounds when fully fueled for launch. The engines use nitrogen tetroxide, an oxidizer, and dimethyl hydrazine, a fuel, as propellants. The first stage includes six engines providing about 1.9 million pounds of thrust at launch. Four engines creating 475,000 pounds of thrust power the Proton’s second stage. The Proton’s third and final stage is powered by a single engine that creates 125,000 pounds of thrust. Assembling the station will be unprecedented task, turning the Earth orbit into a constantly-changing construction site. More than 100 elements will be joined over the course of 45 assembly flights using the Space Shuttle and two types of Russian rockets. An international team of astronauts and cosmonauts will do much of the work by hand, performing more space works in just five years than have been conducted throughout the history of space flight. They will be assisted by a new generation of robotic arms, hands and perhaps even free-flying robotic «eyes». The international partners, Canada, Japan, the European Space Agency, are supposed to contribute the following key ele ments to the ISS: Canada is to provide a robotic arm to be used for assembly and maintenance tasks on the station. The European Space Agency is building a pressurized laboratory to be launched on the Space Shuttle. Japan is building a laboratory module with an attached platform where experiments can be exposed to space as well as logistics transport vehicles. Scientists believe the ISS to be the most advanced base for de veloping technologies, systems and procedures to enable safe, effi cient and permanent human presence in space. Cryptography From e-mail to cellular communications, from secure Web ac cess to digital money, cryptography is an essential part of today’s information systems. The only way to protect a message is to en code it with some form of encryption. Data encryption is very im portant for network security, particularly when sending confidential information. Encryption is the process of encoding data so that un authorized users can’t read it. Decryption is the process of decod- ing encrypted data transmitted to you. The most common methods of protection are passwords for access control, encryption and de cryption systems, and firewalls. Firewall is a software and hardware device that allows limited access to an internal network from the Internet. Cryptography helps provide accuracy and confidentiality. It can prove your identity or protect your anonymity. It can prevent vandals from changing your Web page and industrial competitors from reading your confidential documents. And in the future, as commerce and communications continue to move to computer networks, cryptography will become more and more vital. But the cryptography now on the market does not provide the level of security it advertised. Most systems are not designed and implemented together with cryptographers. Present-day computer security is a house of cards; it may stand for now, but it can’t last. Electronic vandalism is an increasingly serious problem. Computer vandals take advantage of technologies newer than the system they attack, using techniques the designers never thought of and even invent new mathematics to attack the system with. No one can guarantee 100 % security. But we can work toward 100 % risk acceptance. Fraud (обман) exists in current commerce systems. Yet these systems are still successful, because the benefits and conveniences are greater than the losses. Some systems are not perfect, but they are often good enough. A good cryptographic sys tem provides a balance between what possible and what is acceptable. The good news about cryptography is that we already have the algorithms and protocols we need to secure our systems. The bad news is that that was the easy part; implementing the protocols suc cessfully requires considerable expertise. Thus, there is an enor mous difference between a mathematic algorithm and its concrete implementation in hardware and software. Design work is the main support of the science of cryptography and it is very specialized. Cryptography combines several areas of mathematics: number theory, complexity theory, information the ory, probability theory, abstract algebra, and formal analysis, among others. Unfortunately, few can do the science properly, and a little knowledge is a dangerous thing: inexperienced cryptogra phers almost always design imperfect systems. Quality systems use published and well-understood algorithms and protocols. Besides, only when cryptography is designed with careful consideration of users’ needs and then integrated, can it protect their systems, re sources, and data. КРАТКИЙ ПОУРОЧНЫЙ ГРАММАТИЧЕСКИЙ СПРАВОЧНИК LESSON 1 § 1. Глагол to be Глагол to be в Present, Past и Future Indefinite (Simple) име ет следующие формы:
В вопросительной форме глагол to be ставится перед под лежащим: Are they students? Они студенты? Where were you yesterday? Где вы были вчера? В отрицательной форме после глагола to be ставится отри цание not: They are not in the library. Они не в библиотеке. § 2. Глагол то have Глагол to have в Present, Past и Future Simple имеет следую щие формы:
Вопросительная форма глагола to have образуется двумя способами:
Do you have a dictionary? У Вас есть словарь? Отрицательная форма глагола to have также образуется двумя способами:
I have no dictionary У меня нет словаря.
I do not have a dictionary У меня нет словаря. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||