Switching off the system

When it is switched off, the system is fully disconnected from the microscope by galvanic separation and no extra signal is left from the controller to the microscope. 

At the moment when the light is switched off, the system still contains the stationary concentration of radicals [R ]s, t = 0. At this moment the polymerization rate will be [by substiting eqn. (54) into eqn. (48)]... 

If at time zero, after the field has been switched off, the system is found in a state with nonvanishing coherences, oy (z 7), Eqs (18.43b,c) tell us that these coherences decay with the dephasing rate constant k. k was shown in turn to consist of two parts (cf. Eq. (10.176) The lifetime contribution to the decay rate of Oy is the sum of half the population relaxation rates out of states z and j, in the present case for 012 and <721 this is (l/2)( 2 i + 1 2)- Another contribution that we called pure dephasing is of the form (again from (10.176)) Zi 2C(0)(K — 22) - system operator that couples to the thermal bath so that — V22... 

NACE RP290 It is a shorter document than BSEN 12696 and is specifically concerned with control criteria which are at the front of the document in Section 2. The first criterion mentioned is 100 mV polarization development or decay to be measured between the rest , equilibrium , or natural corrosion potential and the instant off potential measured O.l-l.O seconds after switching off the system. The instant off potential is required to remove the iR drop ... 

In the case of higher concentrations of GNR, the 5 s on pulse for both the 1.5 and 3 nM systems did induce a phase change to the H2 and L2 phase structures. At 3 nM, complete transformation to the L2 phase occurred by the end of the 5 s irradiation, while the lower 1.5 nM concentration resulted in a mixed H2 -I- L2 phase, indicating a reduced heating effect (Fig. 12.28). Again, when the laser was switched off, the system ultimately returned to the initial V2 (Pn3m) phase structure. Interestingly, on conversion from the L2 or L2 -I- H2 state back to the V2... 

In the cathodic protection of storage tanks, potentials should be measured in at least three places, i.e., at each end and at the top of the cover [16]. Widely different polarized areas arise due to the small distance which is normally the case between the impressed current anodes and the tank. Since such tanks are often buried under asphalt, it is recommended that permanent reference electrodes or fixed measuring points (plastic tubes under valve boxes) be installed. These should be located in areas not easily accessible to the cathodic protection current, for example between two tanks or between the tank wall and foundations. Since storage tanks usually have several anodes located near the tank, equalizing currents can flow between the differently loaded anodes on switching off the protection system and thus falsify the potential measurement. In such cases the anodes should be separated. 

A small tank was filled every day with sufficient raw material to last until the following day. The worker watched the level in the tank and switched off the filling pump when the tank was 90% full. The system worked satisfactorily for several years before the inevitable happened and the worker allowed the tank to overfill. A high level trip was then installed to switch off the pump automatically if the level exceeded 90%. To the surprise of engineering staff the tank overflowed again after about a year. When the trip was installed it was assumed that ... 

The failure of an inbuilt motor will lead to products of decomposition and serious contamination of the system, which must then be thoroughly cleaned. Internal and external motor protection devices are fitted with the object of switching off the supply before such damage occurs. 

The method is to switch off the compressor after a short running period, and so stop the flow of thermal energy into the condenser, hut continue to run the condenser until it has reached amhient conditions. The refrigerant vapour pressure can then he determined from the coolant temperature, and any increase indicates nonrefrigerant gas in the system. 

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