Feedback energy

Fully controlled thyristor inverter in anti-parallel to feedback energy... 

Resistive-feedback Energy rate Dynamic range — 4 X lO to 7 X 10 ... 

At still higher fields carriers can acquke enough energy from motion in an electric field to create electron—hole paks by impact ionization. Eor siUcon the electron ioniza tion rate, which is the number of paks generated per cm of electron travel, depends exponentially on electric field. It is about 2 X 10 cm for a 50 kV/cm field at 300 K. The electric field causes electrons and holes so created to travel in opposite dkections. They may create other electron—hole paks causing positive feedback, which leads to avalanche breakdown at sufficiently high fields. 

Measurements and Audits. The enabling element of continuous improvement is measurement. An old rule of thumb says that increased accuracy in measuring an energy use ultimately yields a reduction in use equal to 10% of the increased closure of the balance. A basic principle of economics is that any thing that is free is used in excess, ie, an unmetered electrical use is bigger than expected by at least 10%. Metering of the cost elements at each unit in a chemical plant provides effective accountabhity. Measurements should be linked via computer software to production as weh as to weather to result in maximum feedback. 

Figure 6.32 Regenerative energy feedback arrangement for a converter unit...

In the preceding sections, combustion was modeled as a prescribed addition of energy at a given speed. The fundamental mechanism of a gas explosion, namely, feedback in combustion-flow interaction, was not utilized. As a consequence, the behavior of a freely propagating, premixed, combustion process, which is primarily determined by its boundary conditions, was unresolved. 

The major mechanism of a vapor cloud explosion, the feedback in the interaction of combustion, flow, and turbulence, can be readily found in this mathematical model. The combustion rate, which is primarily determined by the turbulence properties, is a source term in the conservation equation for the fuel-mass fraction. The attendant energy release results in a distribution of internal energy which is described by the equation for conservation of energy. This internal energy distribution is translated into a pressure field which drives the flow field through momentum equations. The flow field acts as source term in the turbulence model, which results in a turbulent-flow structure. Finally, the turbulence properties, together with the composition, determine the rate of combustion. This completes the circle, the feedback in the process of turbulent, premixed combustion in gas explosions. The set of equations has been solved with various numerical methods e.g., SIMPLE (Patankar 1980) SOLA-ICE (Cloutman et al. 1976). 

Figure 10-15 shows the output vs. input energy relation with a clear threshold at a pump pulse energy of approximately 1.5 nJ. This value is an order of magnitude lower than the threshold for the observation of ASE in simple planar waveguides, i.e. without distributed feedback but prepared with the same conjugated polymer. 

There is an important feedback factor which cannot be properly evaluated at this time. It concerns future municipal investment in a specific waste control system. This could result in legislation controlling the input of important potential waste materials to the municipality. For example large capital investment in a heat/energy recovery system based on incineration might induce legislative restrictions on low calorific materials like metals and glass. 

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