Applied Process Control

6Problem Solutions – Estimation of Variables and Model Parameters from Plant Data

S_6.1 6.1.1

MATLAB® Program code for Solution 6.1

% Cross-correlations and autocorrelations for Problem 6.1

% Tank & Pipeline

clear all;

close all

Tend=7200;

dt=10;

Nstep=Tend/dt;

V=1;            % m3 (tank)

Vp=1;           % m3 (pipe)

F=5/3600;       % m3/s

CA1=50;         % ppm (initialised at mid-range)

pointer_SHIFT=round(Vp/(F*dt));

Nstack=pointer_SHIFT+1;

CA1stack=CA1*ones(Nstack,1);

pointer_NOW=Nstack;

CA0plot=zeros(Nstep,1);

CA1plot=zeros(Nstep,1);

CA2plot=zeros(Nstep,1);

tplot=zeros(Nstep,1);

N=200;         % max no. of steps in correlation functions

for i=1:Nstep

    CA0=100*rand();

    CA1=CA1+(dt/V)*F*(CA0-CA1);  % simple Euler integration)

    pointer_NOW=pointer_NOW+1;   % cyclical file

    if (pointer_NOW>Nstack)

 pointer_NOW=pointer_NOW-Nstack; ...