2 views (last 30 days)
Show older comments
Max van den Heuvel on 16 Sep 2021
-
-
Link
Direct link to this question
https://matlabcentral.mathworks.com/matlabcentral/answers/1454764-how-to-optimize-nonlinear-multiple-input-model-with-multiple-constraints
Answered: Alan Weiss on 20 Sep 2021
Open in MATLAB Online
I'm looking to find optimum parameter values for a bioprocess. Maximise glucose & xylose production, while constraining furfural produced, and make sure glucose & xylose production stay within feasable numbers (function g_glu/g_xyl is in % of aqeaous so it can not be bigger than 1 (100%)).
The model looks something like this.
maximize => f(x1,x2,x3) = 2*f_glu(x1,x2,x3) + f_xyl(x1,x2,x3) (all nonlinear functions)
constraints:
10 < x1 < 50
130 < x2 < 170
11 < x3 < 89
0 < g_glu(x1,x2,x3) < 1
0 < g_xyl(x1,x2,x3) < 1
g_fur(x1,x2,x3) < 3
So far I have tried the live optimisation editor and lagrange but I am not good at writing code and get stuck everytime. I'll dump some of the code that I've writting down below
% LIVE OPTIMISATION EDITOR
function f = objectiveFcn(optimInput)
z1 = optimInput(1);
z2 = optimInput(2);
z3 = optimInput(3);
f = -2*((0.442*z2-0.207*z3-0.367*exp(-z3)*exp(-z1)+1.33*z3*exp(-z3) +0.348) - (0.192*z1 - 0.624*exp(-3*z3)+ 0.507*z2^(1/2)- 0.11* abs(z3)^2*abs(z2)* abs(2*z3 +z1) + 0.66)*(0.916886995261484 - 0.26709662073194) + 0.26709662073194)*1.76 - ((0.192*z1 - 0.624*exp(-3*z3)+ 0.507*z2^(1/2)- 0.11* abs(z3)^2*abs(z2)* abs(2*z3 +z1) + 0.66) * (1.00459544182241 - 0.200345860452685) + 0.200345860452685)*2.958;
end
function [c,ceq] = constraintFcn(optimInput)
% Note, if no inequality constraints, specify c = []
% Note, if no equality constraints, specify ceq = []
z1 = optimInput(1);
z2 = optimInput(2);
z3 = optimInput(3);
c(1) = z1 - 50;
c(2) = 10 - z1;
c(3) = z2 - 170;
c(4) = 130 - z2;
c(5) = z3 - 89;
c(6) = 11 - z3;
ceq = [];
end
% LAGRANGE FORMULA
syms z1 z2 z3 lambda
%conversion rates from normalization to (%)
fur_min = 0.0020923694565838 ;
fur_max = 0.17896582936453 ;
glu_min = 0.26709662073194 ;
glu_max = 0.916886995261484 ;
xyl_min = 0.200345860452685 ;
xyl_max = 1.00459544182241 ;
% functions (normalized)
glu_n = 0.442*z2-0.207*z3-0.367*exp(-z3)*exp(-z1)+1.33*z3*exp(-z3) +0.348 ; % glucose function (normalized)
xyl_n = 0.192*z1 - 0.624*exp(-3*z3)+ 0.507*z2^(1/2)- 0.11* abs(z3)^2*abs(z2)* abs(2*z3 +z1) + 0.66 ; % xylose function (normalized)
fur_n = 0.332*z3*z2^2 - 0.0289*z3 + 0.332*z2*z1^2 + 0.332*z1*z2*z3 + 0.00825 ; % furfural function (normalized)
glu_p = glu_n * (glu_max - glu_min) + glu_min ; % glucose function in (%)
xyl_p = xyl_n * (xyl_max - xyl_min) + xyl_min ; % xylose function in (%)
fur_p = fur_n * (fur_max - fur_min) + fur_min ; % furfural function in (%)
glu = glu_p * 2.958 ; % glucose function in (g)
xyl = xyl_p * 1.584 ; % xylose function in (g)
% constraints
fur = (fur_p * 1.76 / 0.9 * 10) <= 3 ; % furfural CONSTRAINT in (g/l)
% hb_z1 <= 50
% lb_z1 >= 10
% hb_z2 <= 170
% lb_z2 >= 130 % HOW DO I PUT THESE CONSTRAINTS IN?
% hb_z3 <= 89
% lb_z3 >= 11
% lb_glu >= 0
% hb_glu <= 1
% lb_xyl >= 0
% hb_glu <= 1
% lagrange functions
f = 2*glu + xyl % maximazation function
L = f - lambda * lhs(fur) % lagrange formula
% calculations
dL_dz1 = diff(L,z1) == 0; % derivative of L with respect to z1 (time)
dL_dz2 = diff(L,z2) == 0; % derivative of L with respect to z2 (temp)
dL_dz3 = diff(L,z3) == 0; % derivative of L with respect to z3 (conc)
dL_dlambda = diff(L,lambda) == 0; % derivative of L with respect to lambda
% outcome
system = [dL_dz1; dL_dz2; dL_dz3; dL_dlambda]; % build the system of equations
[z1_val_n, z2_val_n, z3_val_n,lambda_val] = solve(system, [z1 z2 z3 lambda], 'Real', true) % solve the system of equations and display the results
0 Comments Show -2 older commentsHide -2 older comments
Show -2 older commentsHide -2 older comments
Sign in to comment.
Sign in to answer this question.
Answers (1)
Alan Weiss on 20 Sep 2021
I doubt that you want a symbolic solution. You probably want numbers. So I suggest that you use the Problem-Based Optimization Workflow, using optimization variables instead of symbolic variables.
Alan Weiss
MATLAB mathematical toolbox documentation
0 Comments Show -2 older commentsHide -2 older comments
Show -2 older commentsHide -2 older comments
Sign in to comment.
Sign in to answer this question.
See Also
Categories
Mathematics and OptimizationOptimization ToolboxSystems of Nonlinear Equations
Find more on Systems of Nonlinear Equations in Help Center and File Exchange
Tags
- optimization
- lagrange
- bioprocess
- constraints
- multiple inputs
- nonlinear
- lambda
- normalise
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!
An Error Occurred
Unable to complete the action because of changes made to the page. Reload the page to see its updated state.
Select a Web Site
Choose a web site to get translated content where available and see local events and offers. Based on your location, we recommend that you select: .
You can also select a web site from the following list
Americas
- América Latina (Español)
- Canada (English)
- United States (English)
- Belgium (English)
- Denmark (English)
- Deutschland (Deutsch)
- España (Español)
- Finland (English)
- France (Français)
- Ireland (English)
- Italia (Italiano)
- Luxembourg (English)
- Netherlands (English)
- Norway (English)
- Österreich (Deutsch)
- Portugal (English)
- Sweden (English)
- Switzerland
- Deutsch
- English
- Français
- United Kingdom(English)
Asia Pacific
- Australia (English)
- India (English)
- New Zealand (English)
- 中国
- 日本Japanese (日本語)
- 한국Korean (한국어)
Contact your local office