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over the Internet long distances, around the world? The answer is very simple: an use pays his/her service provider a monthly or hourly fee. Part of this fee goes towards its costs to connect to a larger service provider. And part of the fee got by the larger provider goes to cover its cost of running a worldwide network of wires and wireless stations.

But saving money is only the first step. If people see that they can make money from the Internet, commercial use of this network will drastically increase. For example, some western architecture companies and garment centers already transmit their basic designs and concepts over the Internet into China, where they are reworked and refined by skilled — but inexpensive — Chinese computer-aided-design specialists.

However, some problems remain. The most important is security. When you send an e-mail message to somebody, this message can travel through many different networks and computers. The data are constantly being directed towards is destination by special computers called routers. Because of this, it is possible to get into any of computers along the route, intercept and even change the data being sent over the Internet. In spite of the fact that there are many strong encoding programs available, nearly all the information being sent over the Internet is transmitted without any form of encoding, i.e. "in the clear". But when it becomes necessary to send important information over the network, these encoding programs may be useful. Some American banks and companies even conduct transactions over the Internet. However, there are still both commercial and technical problems which will take time to be resolved.

Internal combustion engine

The engine is the powerhouse of the car. It converts the heat produced by burning fuel into mechanical energy to move the wheels. The fuel, normally a

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mixture of petrol and air, is burned (or combusted) in closed cylinders inside the engine. Engines which burn fuel are also used to power jets and rockets.

In a car, petrol and air are mixed in the carburettor and drawn into a combustion chamber at the top of each cylinder. Pistons inside the cylinders compress the mixture, which is then ignited by a spark from the spark plug. As the mixture burns, it expands rapidly, forcing the piston down.

Steel connecting rods connect the pistons to the crankshaft, which in turn is linked to the wheels of the car. The pistons move down causing the crankshaft to revolve and push the wheels round.

The engine is made of two basic parts bolted together: the cylinder head and the cylinder block. The cylinder block contains the crankshaft. The cylinder head holds the combustion chambers and the camshaft. This controls the opening and closing of the inlet and outlet valves, which draw the petrol and air into the chamber and expel the vapour, or exhaust gases, produced by the burned fuel.

As the piston moves down, the inlet valve opens. The fuel and air mixture is sucked into the cylinder and the inlet valve closes. The piston moves up, compressing the mixture. The spark plug then ignites the fuel. Heal generated by the burning fuel forces the piston back down the cylinder, and the outlet, or exhaust valve, opens to allow the burned gases to escape. This causes the piston ю rise again.

The exhaust gases leave the engine at high pressure. If they were allowed ю escape directly into the atmosphere, they would produce a loud noise. To prevent this, the exhaust pipe, or manifold, directs the gases to the silencer.

Molten metal metering

A concept in rapid pouring, that automatically delivers a metered amount of molten metal to a moulding line at a rate in excess of 500 moulds an hour, is available from Inductotherm Europe Limited.

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