Вариант № 2

(Автоматизация)

Automation

We now use the term automation for specific techniques combined to operate automatically in a complete system. These techniques are possible because of electronic devices, most of which have come into use in the last thirty years. They include program, action, sensing or feedback, decision, and control elements as components of a complete system.

The program elements determine what the system does and the step-by-step manner in which it works to produce the desired result.

The action elements are those which do the actual work. They may carry or convey materials to specific places at specific times or they may perform operations on the materials. Perhaps the most important part of an automated system is sensing or feedback. Sensing devices automatically check on parts of the manufacturing process such as the thickness of a sheet of steel or paper. This is called feedback because the instruments return or feed back this information to the central system control.

The decision element is used to compare what is going on in the system with what should be going on, it receives information from the sensing devices and makes decisions necessary to maintain the system correctly. The control element consists of devices to carry out the commands of the decision element. These devices make the necessary corrections or adjustments to keep the system in conformity with its program.

(Промышленная электроника)

Processing hardware

The purpose of processing hardware is retrieve, interpret and direct the execution of software instructions provided to the computer. The most common components of processing hardware are the Central Processing Unit and main memory.

The Central Processing Unit (CPU) is the brain of the computer. It reads and interprets software instructions and coordinates the processing activities that must take place. The design of the CPU affects the processing power and the speed of the computer as well as the amount main memory it can use effectively. With a well-designed CPU in your computer, you can perform highly sophisticated tasks in a very short time.

Memory is the system of component of the computer in which information is stored. There are two types of computer memory: RAM and ROM.

RAM (random access memory) is the volatile computer memory, used for creating loading, and running programs and for manipulating and temporarily storing data;

ROM (read only memory) is nonvolatile, non-modifiable computer memory, used to hold programmed instructions to the system.

The more memory you have in your computer, the more operations you can perform that is the faster it works.

(Электроснабжение)

Electric Charge and its Conservation: the Electron

One of the fundamental fads concerning electrical forces is that, in contrast to gravitational forces, one may have both attractive and repulsive forces between electrically charged bodies. If two bodies are brought into contact with the same terminal of a battery or power line or charged by using identical methods of any sort, it is found that they repel each other when placed near each other. On the other hand, if brought into contact with the opposite terminal of a battery, the bodies attract each other.

This experimental fact led to the assumption that there exist two kinds of electricity, originally termed positive and negative, respectively. When a body has been electrified, we say that that electric charge has been transferred to the body, positive or negative as the case may be. There is a fundamental law concerning electric charge, namely, that no electric charge can ever be created or destroyed. Whenever a positive charge is created, there is always created an equal amount of negative charge. This law called the law of conservation of electric charge is one of the most fundamental laws of physics.

(Химия)

Isotope separation

Today much work is devoted to the improvement of existing isotope separation techniques and the discovery of new ones. The demand for some isotopes is sufficient to overcome difficulties in implementing a separation process. This is true for hydrogen isotopes: industrial processes are established. Demand for other isotopes is often not strong enough to lead to widespread use of enriched materials. Such is the case for elements in the middle mass range.

The most scientifically and technologically demanding separation and purification process is isotope separation. Many effects in physics and chemistry result from a difference in neutron number. However, the observation of such an effect does not constitute an isotope separation technique, nor does the observation that such an effect leads to a small separation of isotope components of a mixture constitute a workable isotope separation process. Each isotope separation method should and can be developed by five steps. The first stage requires theoretical and experimental measurement of potential classic or quantum isotope effects. The latter are revealed in isotope shifts of atomic and molecular spectra. The second stage involves either measurement of the single-stage separation factor of a suitable separation device or the measurement of the equilibrium constant between two phases. A third stage is the amplification of the single-stage isotope fractionation by suitable cascade or column design. This can be carried out on a laboratory scale. The fourth step requires technological and economic assessment of large-scale production processes. Finally in the fifth step the evaluation and comparison of the growing risk of the process should be considered.

(Машиностроение)

Welding

Welding is a process when metal parts are joined together by the application of heat, pressure, or a combination of both. The processes of welding can be divided into two main groups:

• pressure welding, when the weld is achieved by pressure;

• heat welding, when the weld is achieved by heat.

Heat welding is the most common welding process used today.

Nowadays welding is used instead of bolting and riveting in the construction of many types of structures, including bridges, buildings, and ships. It is also a basic process in the manufacture of machinery and in the motor and aircraft industries. It is necessary almost in all productions where metals are used.

The welding process depends greatly on the properties of the metals, the purpose of their application and the available equipment. Welding processes are classified according to the sources of heat and pressure used: gas welding, arc welding, and resistance welding. Other joining processes are laser welding, and electron-beam welding.

Gas welding is a non-pressure process using heat from a gas flame. The flame is applied directly to the metal edges to be joined and simultaneously to a filler metal in the form of wire or rod, called the welding rod, which is melted to the joint. Gas welding has the advantage of using equipment that is portable and does not require an electric power source. The surfaces to be welded and the welding rod are coated with flux, a fusible material that shields the material from air, which would result in a defective weld.

(Гражданское строительство)

Devices used for fastening

Many connections in wood structures depend on direct bearing of one member of the structure on another for their strength. Various simple fasteners are used for constructing purposes. Of them wood fasteners include nails, screws, bolts, anchors and some others.

Nails are generally made of plain steel. It is of interest to note that steel used for nails is uncoated steel. Practically, nails are sharpened metal pins driven into wood with a hammer or a mechanical nail gun. There exist different types of nails. Among them common nails and finish nails are the two types most frequently used for fastening. Common nails have flat heads and are used for most structural connections in light framing constructions. The main property of finish nails is that they are headless. Finish nails are used to fasten finish wood work.

One can see that finish nails are the same length as common nails. Nails are usually named according to the purpose for which they are used as flooring, roofing, etc. Besides common and finish nails, there exists a great variety of other shapes. Face nail is a nail driven through a side of one wood member into the side of another one.

As to the screw nail, it has the form of a spiral. It turns like a screw when it is driven with a hammer.

Nails that are exposed to rain, snow, and fog should be of a corrosion-resistant type.

(Экология)

The Nitrogen Cycle

It is more complex than the carbon and phosphorus cycles because it has both a gas phase and a mineral phase. The main reservoir of nitrogen is the air, which is about 78 percent nitrogen gas (N2). Plants cannot utilize nitrogen gas directly from the air; instead the nitrogen must be in a mineral form, such as ammonium ion (NH) or nitrate ion (NO). A number of bacteria and also certain blue-green algae, which are actually bacteria, can convert nitrogen gas to the ammonium form, a process called biological nitrogen fixation. Most important among these nitrogen-fixing organisms is a bacterium called Rhizobium, which lives in nodules on roots of legumes, members of the pea-bean family of plants. This is another example of symbiosis. The legume provides the bacteria with a place to live and with food (sugar) and gains a source of nitrogen in return. Fixed organic nitrogen is passed from the legumes to other organisms in the ecosystem through food chains.

As animals break down proteins and other organic compounds containing nitrogen for energy in cell respiration, the nitrogen is excreted, generally in the ammonium ion form. Bacteria in the soil may convert the ammonium ion to the nitrate form, but either form may be reabsorbed by any plants, thus creating an ongoing cycle. However, another kind of bacterium in the soil gradually changes the nitrate ion back to nitrogen gas. Consequently, nitrogen will not accumulate in the soil. Some nitrogen gas is also converted to the ammonium form by discharges of lightning in the process known as atmospheric nitrogen fixation and comes down with rainfall, but this is estimated to be only about 10 percent of the amount of biological nitrogen fixation.

(Автомобилестроение)

Internal combustion engine

The first internal combustion engine light enough in weight was the gasoline engine, invented by a German named Otto.

At the same time Dr. Rudolph Diesel was working on the diesel engine. The Diesel engine is similar to the gasoline engine in many ways. There are many variations in engine arrangements, but the basic parts of most 4-stroke cycle engines are similar.

In the in-line arrangement the cylinders are lined up in a single row. The V-type engine is called so as the cylinders form the letter V.

The diesel engine gets its power from the expansion of burning gases. The diesel engine depends on the heat of compression for ignition of the fuel.

Liquid fuel that contains more heat energy than gasoline is diesel oil.

Diesel oil is slower burning, but it produces more power. Diesel engines also must be heavier than gasoline engines, but they are more efficient when working under heavy loads at low speeds.

The advantages of the diesel over the gasoline engine are as follows: a) more economic operation; b) higher compression ratio; c) reduced maintenance costs; d) good pulling power.

(Экономика)

Finance and financial system

Finance is the provision of money at the time when it is needed. It is a system of monetary relations leading to formation, distribution and use of money in the process of its turnover between economic entities.

The financial system is the network of institutions through which firms, households and units of government get the funds they need and put surplus funds to work.

Savers and borrowers are connected by financial intermediaries including banks, thrift institutions, insurance companies, pension funds, mutual funds, and finance companies.

Finance in an economic system comprises two parts: public finance and finance of economic entities.

Public finance is the provision of money (by the community through taxes) to be spent by national and local government authorities on projects of national and local benefit. It is a collective term for the financial flows and also the financial institutions of the public sector.

Public finance has the following four functions: a) the provision of essential services; b) the encouragement or control of particular sectors of the economy; c) the implementation of social policy in respect of social services, and d) the encouragement of the growth of economy as a whole.

The major instrument of any financial system is the budget. In a market-oriented economy, the budget is the most important tool for achieving national priorities and goals through the allocation and distribution of resources, and the maintenance of a stable macroeconomic environment.