Internal Decoupling Control

Several process control design methods, such as the Generic Model Control (GMC) [41], the Globally Linearizing Control (GLC) [37], the Internal Decoupling Control (IDC) [7], the reference system synthesis [8], and the Nonlinear Internal Model Control (NIMC) [29], are based on input-output linearization. 

J.B. Balchen, B. Lie, and I. Solberg. Internal decoupling in nonlinear process control. Modeling Identification and Control, 9 137-148, 1988. 

Hamilton s equations form a set of coupled first-order differential equar tions which under normal conditions can be numerically integrated without any problems. The forces —dVi/dR and —dVi/dr and the torque —dVj/d7, which reflect the coordinate dependence of the interaction potential, control the coupling between the translational (R,P), the vibrational (r,p), and the rotational (7,j) degrees of freedom. Due to this coupling energy can flow between the various modes. The translational mode becomes decoupled from the internal motion of the diatomic fragment (i.e., dP/dt = 0 and dR/dt =constant) when the interaction potential diminishes in the limit R — 00. As a consequence, the translational energy... 

Several of the control loops in Figure 21.35 are provided for inventory control, in three level-control loops and two pressure-control loops. Note, however, that the pressure in V-100 is assumed to be constant and loop PC-1 is not simulated by HYSYS.Plant. In contrast, pressure control is crucial to maintain stable internal flows in the column. Finally, because the feed flow rate and temperature controllers are decoupled from the rest of the process, they are not included in the C R analysis. Consequently, the interactions to be analyzed involve the four valves V-7, V-9, V-10, and V-12, and four controlled variables Xdj, JC/u (mole fractions of benzene in the distillate, MCB in the bottoms, and HCl in the absorber overhead stream, respectively) and Tg, the recycle temperature. Note that to improve the dynamic performance, the temperature of tray 4 is controlled rather than the distillate benzene mole fraction. 

Commault, C., Descusse, J., Dion, J.M., Lafay, J.F., Malabre, M. New decoupling invariants the essential orders. International Journal of Control, 44(3) 689-700, September, 1986. 

In -the moderation-control method for S% enriched UFii, criticality safety is assured by control of two parameters- the U enrichment and the hydrogen moderation. Topical subjects to be reviewed in method development include UF , purity control in liquefaction operations the Influence of container size on internal and external moderntion effects decoupling properties of the cylinder wall In water-moderated UFa arrays special neutron multiplication experiments with large UFo assemblies derivation of moderation control limits large cylinder cleaning procedures and protective packaging. The administrative requirements for method application are al.so discussed briefly. 

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