ИНОСТРАННЫЙ ЯЗЫК В ТЕХНИЧЕСКОМ УНИВЕРСИТЕТЕ (956018), страница 47
Текст из файла (страница 47)
To be read after Lesson 8
The Driving Lesson
Miss Green: Good afternoon. My name is Miss Green and I'm your driving instructor. Is this your first lesson?
Simon: It is my first lesson at this driving school.
M. G.: Oh, you've been to another one?
S.: Yes. The Greenwich school of driving. But I stopped
going there.
M. G.: Why? Weren't the lessons good enough?
S.: They were good but my instructor left.
M. G.: Really? Well, let's see what you can do. I want you to
drive down this road and turn left at the end.
S.: Yes, all right.
M. G.: You drive very well! I'm sure you'll pass your test. All
my pupils pass their tests. Oh, look out! That lorry!
S.: You said turn left at the end.
M. G.: When you want to turn a corner, slow down and look
first. You nearly hit that lorry. Please, be careful. Now turn right at the traffic lights... Right, not left!
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S.: Sorry it was too late. I've turned left now.
M. G.: Didn't you see the No Entry sign? This is a one-way
street.
S.: Why are those drivers shouting?
M. G.: Because you're driving the wrong way down a one-way
street. Stop the car, please, and turn it round.
S.: I'm not very good at that.
M. G.: Mind that red car!
S.: Madman! He nearly hit me!
M. G.: He was right and you were wrong. Why didn't you
wait? Now you are blocking the road. You want reverse gear. Turn the wheel... more ... more ... Not too
fast! Oh, what have you done now?
S.: It is all right. I went into the lamp-post but it is still
standing. I didn't knock it down.
M.G.: Oh, but look at the back of the car.
S.: Sorry, but you said «reverse».
M.G.: I didn't say «drive into the lamp-post». Well, you've
turned the car round now, so drive back to the traffic
lights and go straight across.
S.: Are we going to the park?
M.G.: The roads are quiter near the park. Oh, not too fast!
S.: The lights are green.
M.G.: Slow down! The lights are changing!
S.: I can't slow down. There! We are across.
M.G.: The lights were red!
S.: It's all right. There were no policemen.
M.G.: I know why your last instructor left. He wanted to stay
alive.
S.: That's not a very nice thing to say. And it's not true.
He left because he wasn't very well.
M.G.: Stop the car, please. Oh, gently!
S.: Sorry. Did you hit your head on the roof?
M.G.: No. Luckily I was wearing the seat belt. Now I want
you to practise driving backwards. Reverse the park
gates. Look first, than reverse in.
S.: Right.
M.G.: Oh, you've hit the gate!... Now you are driving on the
grass!
S.: I'm going backwards down the hill and I can't stop!
Help me!
M.G.: Use the brakes! Don't drive into the lake!
S.: Too late.
M.G.: Look what you've done. You reversed into a lamp
post. You hit the park gate. Now you've driven into the lake. Oh, why didn't you stay with the other driving school?
S.: They had no more cars left.
Heavy-Lift Dirigible
Unlike other new dirigible projects the giant CargoLifter CL 160 (Germany) is aimed at heavy-lift cargo applications, not at tourism or advertising. It will be the beginning of a new era in freight transport.
The 260-meter-long, 65-meter-diameter semi-rigid airship will be capable of transporting 160 ton loads-equivalent to 36 standard 40-ft containers — to out-of-the-way (remote) construction sites 10,000 km away. With a cruise speed of just 80-120 km/hr the CL 160 would not get the load to its destination nearby as fast as a heavier-than-air craft such as Antonov An-124, but it would also not require the landing facilities needed for the unusually large aircraft.
Moored (причаливать) above the delivery site, the airship will lower loads using an onboard crane without actually having to touch down. A crew of five, including navigator and two cargo-masters (высококвалифицированные рабочие) would man the ship.
In fact, the CargoLifter project was born of a logistics need expressed by manufacturers of electric generators, turbines and other outsized (i.e., larger than the usual size) machinery.
Rolls-Royce-Turbomeca turboshaft engines are to be used for maneuvering the big airship, cruise being provided by diesel power-plants.
What Is GPS?
The Global Positioning System (GPS) is a satellite-based navigation system made up of a network of 24 satellites. GPS was originally intended for military applications, but now the systems is available for civilian use. GPS works in any weather conditions, anywhere in the world, 24 hours a day.
GPS satellites circle the earth twice a day in a very precise orbit and transmit signal information to Earth. GPS receivers take this information and use triangulation to calculate the user's exact location. Essentially, the GPS receiver compares the time a signal
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was transmitted by a satellite with the time it was received. The time difference tells the GPS receiver how far away the satellite is. Now, with distance measurements from a few more satellites, the receiver can determine the user's position and display it on the unit's electronic map.
A GPS receiver must be locked on to the signal of at least three satellites to calculate a 2D position (latitude and longitude) and track (прослеживать) movement. With four or more satellites in view, the receiver can determine the user's 3D position (latitude, longitude and altitude). Once the user's position has been determined, the GPS unit can calculate other information, such as speed, bearing (пеленг), track, trip distance, distance to destination, sunrise and sunset time and more.
Today's GPS receivers are extremely accurate within an average of three to five meters thanks to their parallel multi-channel design.
The 24 satellites that make up the GPS space segment are orbiting the earth about 12,000 miles above us. They are constantly moving, making two complete orbits in less than 24 hours. These satellites are travelling at speeds of roughly 7,000 miles an hour.
GPS satellites are powered by solar energy. They have backup batteries onboard to keep them running in the event of a solar eclipse (затмение), when there's no solar power. Small rocket boosters on each satellite keep them flying in the correct path.
Here are some other interesting facts about the GPS satellites:
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The first GPS satellite was launched in 1978.
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A full constellation (созвездие) of 24 satellites was achieved in 1994.
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Each satellite is built to last about 10 years. Replacements are constantly being built and launched into orbit.
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A GPS satellite weighs approximately 2,000 pounds and is about 17 feet across with the solar panels extended.
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Transmitter power is only 50 watts or less.
GPS satellites transmit two low power radio signals. The signals travel by line of sight, meaning they will pass through clouds, glass and plastic but will not go through most solid objects such as buildings and mountains.
A GPS signal contains three different bits of information — a pseudorandom code, ephemeris data and almanac data.
Some factors that can degrade the GPS signal and thus affect accuracy include the following:
1. The satellite signal slows as it passes through the atmosphere.
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The GPS signal is reflected off objects such as tall buildings or large rock surfaces before it reaches the receiver. This increases the travel time of the signal, thereby causing errors.
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A receiver's built-in clock is not as accurate as the atomic clocks onboard the GPS satellites. Therefore, it may have very slight timing errors.
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The more satellites a GPS receiver can «see,» the better the accuracy. Buildings, terrain, electronic interference, or sometimes even dense foliage (листва) can block signal reception, causing position errors or possibly no position reading at all. GPS units typically will not work indoors, underwater or underground.
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 structures — 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 American companies have built the world's deepest production platforms 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 sinking under its own weight as the bathyscaphes did. This design is more like an aeroplane than a balloon. It could one day make exploring 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.
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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 ceramic 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 streamlined 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 development of laser technology and its application in science, industry and commerce. Laser cutting, welding and machining are beginning 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 %. Japan 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.
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The Germany met 90 % of its demands through domestic producers. 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 laser 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 laser 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 отверстия) 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 applications 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, optical 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 retrieved 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, multimedia 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 electromagnet 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 devices are good for back up purposes and storage of large amounts of information such as a dictionary or encyclopaedia.
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