Self-braking effect

The high hardness of chromium oxide resulting from its crystal structure is exploited in polishing agents for metals and in brake linings. Addition of a small amount of chromium oxide to magnetic materials of audio and video tapes imparts a self-cleaning effect to the sound heads. 

If a second particle is present in the system, as will be the case in almost any imaginable situation, the force field produced by one moving particle will affect and be affected by the second (Fig. 4.10b). Because the second particle produces a braking effect on the movement of the first, the effective diffusion coefficient of particle 1 will decrease in a manner proportional to the distance separating the two. If it is assumed for purposes of simplification that particle 2 does not move, the relationship between the braking effect and the self-diffusion coefficient can be written as... 

Safety goals often describe mutual effects of possible malfunctions. A defective, far too high motor torque leads at a certain value, intensity or duration to a dangerous and for the driver, uncontrollable self-acceleration of the vehicle. A defective far too low motor torque could lead to an uncontrollable delay up until self-braking. This is why the safest function is usually a corridor, which is chosen by design limitations and/or the controllability through the driver (see Fig. 4.15). 

While familiarisation with the area to be visited is important, an essential part of the risk assessment procedure, that is often overlooked, is familiarisation with the mode of transport to be used. If this is a self-drive minibus, prior to the journey, a check should be carried out on basic safety features such as tyres, lights, windscreen washers/wipers, brakes, availability of first aid kit and fire extinguisher, fluid levels, doors (operate freely and close securely) and warning instruments. Driver effectiveness and fatigue is also influenced by poor driving position and conditions so, before setting off the driver should adjust the seat, the mirrors and check that they can reach all the essential controls. 

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