. Design for a brain. Brain -- Physiology; Central nervous system -- Mathematical models; Neurophysiology. 4/13 DESIGN FOR A BRAIN of searchlight, anti-aircraft guns, rockets, and torpedoes, and facilitated by the great advances that had occurred in electronics. As a result, a host of new machines appeared which acted with powers of self-adjustment and correction never before achieved. Some of their main properties will be described in S. 4/14. The nature, degree, and polarity of the feedback has a decisive effect on the stability or instability of the system. In the Watt's governor or in the
. Design for a brain. Brain -- Physiology; Central nervous system -- Mathematical models; Neurophysiology. 4/13 DESIGN FOR A BRAIN of searchlight, anti-aircraft guns, rockets, and torpedoes, and facilitated by the great advances that had occurred in electronics. As a result, a host of new machines appeared which acted with powers of self-adjustment and correction never before achieved. Some of their main properties will be described in S. 4/14. The nature, degree, and polarity of the feedback has a decisive effect on the stability or instability of the system. In the Watt's governor or in the thermostat, for instance, the connection of a part in reversed position, reversing the polarity of action of one component on the next, may, and probably will, turn the system from stable to unstable. In the reaction circuit of the radio set, the stability or instability is determined by the quantitative rela- tion between the two effects. Instability in such systems is shown by the development of a ' runaway '. The least disturbance is magnified by its passage round the circuit so that it is incessantly built up into a larger. 4^=^3 3^ 4 Figure 4/12/1. and larger deviation from the resting state. The phenomenon is identical with that referred to as a ' vicious circle '. The examples shown have only a simple circuit. But more complex systems may have many interlacing circuits. If, for instance, as in S. 8/8, four variables all act on each other, the diagram of immediate effects would be that shown in Figure 4/12/1 (A). It is easy to verify that such a system contains twenty interlaced circuits, two of which are shown at B and C. The further development of the theory of systems with feed- back cannot be made without mathematics. But here it is sufficient to note two facts : a system which possesses feedback is usually actively stable or actively unstable ; and whether it is stable or unstable depends on the quantitative details of the particular arrangement. 4/13. It will be not
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Keywords: ., bookcentury1900, bookpublishernewyorkwiley, booksubjectneurophys
