Electromagnetic electric current sensors

An active magnetic axial bearing consists of two stators and a rotor disk (Figure 6-4). A sensor located at the end of the shaft monitors and maintains the rotor position between the two stators. The principle of operation is the same for both axial and radial bearings any deviation from the normal position of the rotor is communicated to the electronic control system, which adjusts the electric current going to the electromagnets to correct the rotor position. 

Balances are devices used to measure mass. When a sample of a substance is placed on the balance pan, gravity on it pushes the pan down with a force proportional to the object s mass. A sensor uses an electromagnet to push the pan back to its original position. The electric current required to push the pan back to its original position is directly proportional to the gravitational force on the object on the pan. The mass of the object is displayed on a digital readout. 

In contra.st to their interaction with applied electric, magnetic or electromagnetic fields, porphyrins and metalloporphyrins can also interact with other chemical species. One might view such interactions as chemo-responsive rather than field-responsive. The development of chemo-responsive materials based on porphyrins, however, is somewhat less advanced. One example of such applications is that porphyrin solids, being highly porous, are involved in the current development of molecularly based molecular sieves or shape-selective solid catalysts. Porphyrins and metalloporphyrins have also been examined for a variety of sensor applications, further proving their importance as a class of chemo-responsive materials. 

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