Texts and exercises on information science. Мартынов О.В. - 16 стр.

UptoLike

ВУЗ: 

СПб ГУАП | Санкт-Петербург

Составители: 

Рубрика: 

31
If a diver wants to know how long he has been down, he can see this from
the display. If a diver needs to spend some minutes at a certain depth for
decompression, he will start his stop watch, and will wait until the time
has elapsed (passed). If a diver wants to know the amount of air left in the
tank, he can see this from the contents display.
A warning signal tells him when he must start his ascent. Before he
descends, the diver sets the time to ascend. If he began his ascent before the
display started flashing, he would be within safe limits. If he did not ascend
then, he would expose himself to decompression sickness. If he started his
ascent and went up too quickly, he would see a warning light «Too fast».
Then he should slow down his ascent.
ASSIGNMENT TO TEXT 10.
I. Read and translate the text.
II. Answer the following questions:
1. What will a computer for scuba divers provide? 2. What will a
display provide? 3. How will the diver estimate the depth? 4. Ноw will the
diver know the amount of air in the tank? 5. In what case will the diver
expose himself to decompression sickness?
III. Make all types of questions to the following sentence:
a computer for scuba divers will provide in one device information
about time, depth and air supply.
IV. Give Russian equivalents:
display, visual information, audible warning, fresh water, current
depth, to be down, stop watch, warning signal, ascent, descent, be within
safe limits.
V. Write out sentences with subordinate clauses of condition and
translate them.
VI. Give summary of the above text.
TEXT 11
Optical Technology
One of the most interesting developments in telecommunication is the
rapid progress of optical communication where optical fibers are replacing
conventional telephone wires and cables. Just as digital technologies greatly
improved the telephone system, optical communication promises a
considerable increase in capacity, quality, performance and reliability of the
32
global telecommunication network. New technologies such as optical fibers
will increase the speed of telecommunication and provide new, specialized
information service. Voice, computer data, even video images, will be
increasingly integrated into a single digital communication network capable of
processing and transmitting virtually any kind of information.
It is a result of combining two technologies: the laser, first demonstrated
in 1960, and the fabrication 10 years later of ultra-thin silicon fibres which can
serve as lightwave conductors. With the further development of very efficient
lasers plus continually improved techniques to produce thin silica fibres of
incredible transparency, optical systems can transmit pulses of light as far as
135 kilometers without the need for amplification or regeneration.
At present high-capacity optical transmission systems are being installed
between many major US cities at a rapid rate. The system most widely used
now operates at 147 megabits per second and accommodates 6,000 circuits
over a single pair of glass fibres (one for each direction of transmission).
This system will soon be improved to operate at 1.7 gigabits per second and
handle 24,000 telephone channels simultaneously.
A revolution in information storage is underway with optical disk
technology.
The first digital optical disks were produced in 1982 as compact disks for
music. They were further developed as a storage medium for computers.
The disks are made of plastics coated with aluminium. The information is
recorded by using a powerful laser to imprint bubbles on the surface of the
disk. A less powerful laser reads back the pictures, sound or information.
An optical disk is almost indestructible and can store about 1000 times more
information than a plastic disk of the same size.
One CD-ROM disk (650 MB) can replace 300,000 pages of text (about
500 floppies), which represents a lot of savings in databases.
The future of optical storage is called DVD (digital versatile disk). A
DVD-ROM can hold up to 17 GB, about 25 times an ordinary CD-ROM.
For this reason, it can store a large amount of multimedia software and
complete full-screen Hollywood movies in different languages. However,
DVD-ROMs are «read-only» devices. To avoid this limitation, companies
also produce DVD rewritable drives.
Besides, it is reported that an optical equivalent of a transistor
has been produced and intensive research on optical electronic
computers is underway at a number of US companies as well as in
countries around the world.

Страницы