Вариант № 3

(Автоматизация)

Automating tooling in FMS

The delivery and changing of cutting tools to the CNC machine tools seems to be a vital requirement in FMS. Typical CNC machine tools consist of permanently attached tool magazines, equipped with automatic tool changers, with capacities of from 30 to 120 cutting tools.

An optimum tooling system would have all required cutting tools stored in the various machine tool magazines. However, tooling requirements generally exceed the machine tool magazine capacities in most practical FMS. Also due to cutter wear and breakage tools must inevitably be replaced.

As for tool delivery two approaches should be mentioned manual and automated. In a manual tool delivery environment, an operator brings the cutters to the machines and manually inserts them into the machine tool magazine. For this system to operate efficiently and with minimal human interference each machine tool magazine capacity would have to be of the order of 120.

Since the aim of FMS is to strive towards untended manufacturing, an automated tool delivery system is generally preferred. Such an automated tool delivery / changing system includes machine tools along with portable tool drums, each capable of storing up to 30 cutting tools.

(Промышленная электроника)

Software

Applications software satisfies your specific need. The developers of application software rely mostly on marketing research strategies trying to do their best to attract more users (buyers) to their software. As the productivity of the hardware has increased greatly in recent years, the programmers nowadays tend to include as much as possible in one programme to make software interface look more attractive to the user. These class of programmes is the most numerous and perspective from the marketing point of view.

Data communication within and between computers systems is handled by system software. Communications software transfers data from one computer system to another. These programmes usually provide users with data security and error checking along with physically transferring data between the two computer's memories. During the past five years the developing electronic network communication has stimulated more and more companies to produce various communication software such as Web-Browsers for internet.

(Электроснабжение)

Direct current and alternative current

When a cell or any other generator is connected so as to form a continuous path of conductors the electrons begin to move through conductors and this is called an electric current, an electric circuit. We know that current is the flow electricity through a circuit. If broken anywhere, the electric circuit will stop carrying a current. There are two main types of current: direct and alternating. When electrons flow in one direction only, the current is called a direct current. When electrons flow first in one direction and then in another in a periodic manner, the current is called an alternating current. An alternating current is a current that changes its direction of flow through a circuit in a periodic manner. Alternating current flows in cycles. The number of cycles per second is termed the frequency of current. In a 60-cycle alternating current circuit, the current flows in one direction 60 times per second and in the other direction 60 times per second.

Two frequencies are in use nowadays: the standard for Europe is 50 cycles per second, while the standard for the USA is 60 cycles per second. A standard frequency has a great advantage since different electrical systems can be interconnected.

(Химия)

Recovery or uranium and plutonium from irradiated nuclear fuel

Nuclear power has been in use for over three decades. For most of that time it has been considered essential to reprocess the fuel in order to recover valuable materials, to make the best use of finite energy resources and to facilitate fission product waste management. Solvent extraction quickly established itself as the dominant chemical process in the recovery of uranium and plutonium from irradiated fuel.

The nuclear industry is at present based almost exclusively on the thermal fission of uranium; a 235U atom is split by a slow neutron to yield energy, fission products, and several more neutrons of which one – slowed by passage through a moderator – causes a further fission. Other neutrons are absorbed by structural materials and other absorbers, by shielding, or by 238U that is then converted by successive nuclear reactions to plutonium. Part of this itself undergoes fission before the net consumption of fissile material, the accumulation of neutron-absorbing fission products, and the structural deterioration of the fuel element require it to be discharged. Most of the uranium remains unchanged (although with a reduced proportion of the fissile isotope 235U) and can be purified for further use; the plutonium is also worth separating for use either as a substitute for 235U in thermal reactors or more effectively in fast neutron reactors as an intermediate in the net conversion of relatively abundant but non-fissile 238U to energy and fission products.

(Машиностроение)

Types of lathes

All the machine-tools operate on either a reciprocating or rotary type principle; either the tool or work reciprocates or rotates. Cutting tools must be hard. A tool must also have the correct cutting angle, and the correct speed to cut satisfactorily. Heat dissipation is another factor in considering the correct speed. The engine lathe has a large range of spindle revolutions and of feeds, and in can cut threads. The bench lathe is adapted to small work, having a maximum swing capacity of 9 inches.

All lathes receive their power through the headstock which may be equipped either with a step-cone pulley drive or a geared-head drive.

The shaper is a flexible machine in many respects complementing the lathe in the work it performs. It has a reciprocating cutting tool, which takes a straight-line cut. It can produce flat surfaces, and by means of special tools, attachments, and devices for holding the work, a shaper can also cut external and internal key-ways, spiral grooves, gear racks, dovetails, T slots and other shapes. The planer, a much larger and heavier machine than the shaper, is designed to remove metal by moving the work in a straight line against a stationary single-edged cutting tool. Special machine-tools are used for honing, lapping and super-finishing.

(Гражданское строительство)

Aluminium in structures

Aluminium is not a new material. Probably the first example of large-scale structural use of aluminium was in 1933 when the floor steel-work of a large road bridge in Pittsburg, Pennsylvania, was replaced with aluminium and the resulting saving in dead weight – about 1 ton/ft run – enabled the bridge to carry with greater safety the increased loads of modern traffic. Apart from the construction of aircraft, aluminium has thus a structural history of about only half a century. Extensive use of aluminium in buildings such as aircraft hangers did not occur until about 30 years ago.

In many ways aluminium has been slow in making progress, mainly because of its cost; it is produced by electrolytic means which requires cheap hydro-electric power. About 10 units of electricity are required to make 1 lb. New reduction plants of large capacity have been coming into service in many parts of the world and these provide increased production with improved efficiency. The use of aluminium in structures may well expand in corresponding manner as simultaneous advances are being made with the development of improved aluminium materials and products.

The principal virtues of aluminium are lightness combined with strength and freedom from corrosion. The extent to which the latter two properties are developed depends on the alloy concerned.

The advantage of lightness – one-third the density of mild steel with nearly the same strength – is particularly of value where weight saving is of importance – in lift bridges, long span roofs, dome roofs, crane jibs and in a wide range of moving and portable structures.

(Экология)

The Phosphorus Cycle

Phosphorus exists in various rock and soil minerals as inorganic phosphate ion (PO). As rock gradually breaks down, phosphate and other nutrient ions are released. Phosphate dissolves in water but does not enter air. Plants absorb phosphate from the soil or water solution, and as it is bonded into organic compounds by the plant it is frequently referred to as organic phosphate. Through food chains, organic phosphate is transferred from producers to the rest of the ecosystem. As with carbon, at each step here is a high likelihood that the organic phosphate will be broken down in cell respiration, releasing inorganic phosphate in urine or other waste. The phosphate may then be reabsorbed by plants to start another cycle.

There is an important difference between the carbon cycle and the phosphorus cycle. No matter where carbon dioxide is released, it will mix and maintain the concentration of carbon dioxide in the air. Mineral nutrients, however, which do not have a gas phase, are recycled only insofar as the wastes that contain them are deposited on the soi1 from which the nutrients originally came. This is basically what happens in a natural ecosystem. However, humans are prone to upset this cycle. A very serious case of humans interfering with the phosphorus cycle is seen in the cutting of tropical rainforests. This type of ecosystem is supported by a virtually 100 percent efficient recycling nutrients. In other words, there are little or no reserves in the soil. When the forest is cut and burned, the nutrients that were locked up the trees are really washed away, and the land is rendered unproductive.

(Автомобилестроение)

Chassis

The main units of the chassis are: the power transmission, running gear and the steering mechanism. The power transmission includes the whole mechanism between the engine and the rear wheels. This entire mechanism consists of the clutch, gearbox, propeller shaft, rear axle, final drive, differential and axle shafts.

At the front of end of the car is the engine. On the back of it is the flywheel. Behind the flywheel is the clutch. The clutch is a friction device connecting the engine with the gears of the gearbox. The main function of the gearbox is to change the speed of the car.

The power is always transmitted by the cardan shaft to the live back axle. The final drive reduces the high speed of the engine to the low speed of the driving wheels. The differential enables the driving wheels to turn at different speeds which are necessary when turning the car. The foundation of the automobile is the frame to which different chassis units are attached.

The rear axle is capable of moving up and down about the frame. The rear axle is an important part of the transmission. It carries the greater portion of the weight of the car.

The steering mechanism is designed for changing the direction of the car.

The breaks are used for stopping the car, for decreasing its speed and for holding the car position.

(Экономика)

Financial policy

Financial policy is a very complex notion covering measures aimed at working out basic concepts, major guidelines, goals and objectives as well as at creating an adequate financial mechanism and at directing financial activities of a country. Financial policy is based on strategic guidelines which set long-term and medium-term prospects for using financial resources and ensure attainment of major economic targets and solution of goals in the social sphere. At the same time a country pursuing its financial policy sets current goals and objectives connected with mobilization and effective utilization of resources and development of productive forces.

Over the past two decades financial problems have exacerbated the world over. Public debts have reached unsustainable levels in a growing number of industrial countries. This development and its results – higher interest rates, lower investment, and slower growth in living standards – have stimulated efforts by policymakers to find solutions to swollen budget deficits.

Central to these solutions is fiscal policy. Fiscal policy is the policy adopted by a government for raising revenue to meet expenditure.