×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Are you an
Engineering professional?
Join Eng-Tips Forums!
• Talk With Other Members
• Be Notified Of Responses
• Keyword Search
Favorite Forums
• Automated Signatures
• Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

#### Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

# Matlab Script Help

## Matlab Script Help

(OP)
Please see the below script I have created to solve the problem. It doesn't work. Can some one help?

clear; close all; clc;
syms x1(t) x2(t) x3(t) x4(t);
r=[-0.05 0 0.03 0.05;
0.05 -0.05 0 0;
0 0.02 -0.02 0;
0 0.03 0.02 -0.05];
D=[0;1;4;0];
X=[x1;x2;x3;x4];
odes=diff(X)==r*X+D;
x1Sol(t)=simplify(x1Sol(t));
x2Sol(t)=simplify(x2Sol(t));
x3Sol(t)=simplify(x3Sol(t));
c=X(0)==[0;0;0;0];
[x1Sol(t), x2Sol(t), x3Sol(t), x4Sol(t)]=dsolve(odes,c)

Consider four ponds connected by streams. Initially, the ponds were pristine.
At time t=0, after environmental accident, the second and third ponds are getting polluted with the sources, releasing pollutant substance with the following rates: f2=1 kg/h and f3=4 kg/h. Pollution spreads via the connecting streams to the other ponds, as shown in the Figure.

For this task, formulate associated differential equations in terms of x1(t), x2(t), x3(t) and x4(t) - time functions, describing pollutant amounts in each lake. Solve problem numerically, using ode45 MATLAB procedure, and DETERMINE the amount of pollutant (in kg) in lake #2 towards the end of 48 hours of contamination. For a specific numerical example, take f12/V1=f41/V4=0.05; f23/V2=f34/V3=0.02; f24/V2=0.03 [all in 1/h].

Figure-2: Four ponds #1, #2, #3 and #4 of volumes V1, V2, V3, V4 [all in m^3], connected by streams with specific flow rates f12, f13, f23, f34, f41 [m^3/h].
Formulate system of the first order ordinary differential equations and solve it numerically, using ode45 procedure.

#### Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

#### Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

#### Resources

Low-Volume Rapid Injection Molding With 3D Printed Molds
Learn methods and guidelines for using stereolithography (SLA) 3D printed molds in the injection molding process to lower costs and lead time. Discover how this hybrid manufacturing process enables on-demand mold fabrication to quickly produce small batches of thermoplastic parts. Download Now
Examine how the principles of DfAM upend many of the long-standing rules around manufacturability - allowing engineers and designers to place a partâ€™s function at the center of their design considerations. Download Now
Taking Control of Engineering Documents
This ebook covers tips for creating and managing workflows, security best practices and protection of intellectual property, Cloud vs. on-premise software solutions, CAD file management, compliance, and more. Download Now

Close Box

# Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

• Talk To Other Members
• Notification Of Responses To Questions
• Favorite Forums One Click Access
• Keyword Search Of All Posts, And More...

Register now while it's still free!