2.21. , :
1) 1. Aluminum is the most problematic material to be used for metallization in maintaining contact stability. 2. A lower resistivity is required for maintaining circuit performance. 3. Use of this self-test technique greatly simplifies field maintenance. 4. For storage and retrieval of data in the bubble-memory use is made of a group of registers and counters for accurately maintaining the position of data. 5. Any system must be designed to require less maintenance. 6. Preventive maintenance is necessary.
2) 1. This entails turning one of the file processors into an input/output unit. 2. Today, plants depend on carbon dioxide and water to survive. In turn, they produce organic matter. 3. Water can turn to a solid. 4. Let us now turn to ceramics. 5. At the turn of the 18th century nobody knew of semiconductors.
3) 1. Sometimes the performance of the circuits can suffer from technological advancement. 2. The systematic approach can anticipate the problems that will arise in future VLSI. 3. The average wire length can be estimated by a very useful statistical formula.
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2.22. -. :
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2.9. . :
1. As you can see from the title the text is devoted to...; 2. The problem arose...; 3. According to the text...; 4. Experiments paved the way to...; 5. Experiments proved...; 6. Research has shown that...; 7. I find the text rather/very...; 8. I've learnt a lot...
Made in Space
Numerous experiments carried out at the Soviet orbital stations have paved the way to the development of methods and means of industrial production in space.
In recent years active research has been going on in one of the fields of space industrialization space material study and production of new materials of better quality on board the spacecraft, ranging from semiconductors for microelectronics to unique and more efficient medicines for the treatment of quite a number of diseases ().
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Conditions on board a space vehicle orbiting the earth drastically differ from.those on its surface. However, all of these conditions can be: simulated on Earth, except for one - prolonged weightlessness.
What can weightlessness be used for? Many well-known physical processes proceed differently due to absence of weight. In case of melts of metals, glasses, or semiconductors, they can be cooled down to the solidification point even in space and then brought back to Earth. Such materials will possess quite unusual properties.
There is no gravitation convection, i.e. movements of gases or liquids caused by difference of temperature in space. Manufacturers of semiconductors know only too well that convection is to blame for the various faults in semiconductors. The technical specialists started their experiments aimed at proving the advantages of the zero- g state for the production of certain materials. In the Soviet Union all orbital stations from Salyut 5 onwards were used for that purpose, as well as automatic space probes and high-altitude rockets. Since 1976, over 600 technological experiments have been staged in the Soviet Union on board its manned and unmanned space vehicles. An impressive number of similar experiments have also been carried out by scientists in other countries.
The experiments proved that scientists were right. Many of the properties of the materials obtained in the zero- g conditions were much better pronounced as compared with those of the specimens produced on Earth.
At the same time, test runs of the installations of the next generation developed for the small-scale industrial production in space have started. One such installation, Korund, has already been tested successfully on board the Salyut station. It has been designed to grow monocrystalline semiconductors possessing unique properties.
In order to launch full-scale industrial production of monocrystalline semiconductors, bioactive preparations and other substances it is not enough just to commission new-generation technology installations. Special space vehicles will also be needed. Research has shown that the acceleration rate on board these vehicles must be reduced to the minimum. Power plants of the capacity of dozens of kw, and later, of hundreds of kw are needed.
2.23. :
1. Intrinsic semiconductor properties. 2. Contributions to the study of semiconductor physics. 3. Silicon and its dominant role as a material for microelectronic circuits. 4. New materials and their potentials.
2.24. :
1. The silicon dioxide is particularly important in the fabrication of integrated circuits. 2. Oxygen influences many silicon wafer properties. 3. Gallium arsenide has a much lower electron mobility than germanium and silicon.
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1. That's just the point... I can also add...; 2.1 don't agree with it... The point is that...
