function xprime=input_multivessel(t,X) 
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%%%%% Program written by Stathis skouras, May 2001. %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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% Number of stages in the top section: 
NT1=25;
% Number of stages in the bottom section (without the reboiler): 
NT2=25;
% Total number of 'stages'  
NT=NT1+NT2+3;  % We include condenser and middle vessel (for practical reasons) and reboiler 

% Inputs
VB=5;                                  % Boilup (kmol/hr)
L0=VB;                                 % Nominal liquid flows in both sections of the column (kmol/hr)

% P-Controllers gains and setpoints 
Kc1=0.413;                             % Proportional controller gain at the top section (Kmol/(hr*C))
Kc2=0.229;                             % Proportional controller gain at the bottom section (kmol/(hr*C))
Tsp1=72.15;                              % Temperature setpoint in the top section (C)
Tsp2=89.1;                            % Temperature setpoint in the bottom section (C)

% Precaution so as condenser and middle vessel do not run empty
Hmin=0.035;                            % Minimum liquid holdup in condenser and middle vessel   

% Store all inputs and disturbances
U(1)=VB; U(2)=L0; U(3)=Kc1; U(4)=Kc2; U(5)=Tsp1; U(6)=Tsp2; U(7)=Hmin;
xprime=multivessel(t,X,U);
t