5740-001 and 6870-001
Math Modeling

Fall 2018

Class meets: MW / 01:25PM-02:45PM in LS 111
Office Hours: F, 02 PM-03PM, JWB 225
Instructor: Andrej Cherkaev, JWB 225, ph. 801-5816822, email: cherk@math.utah.edu (subject line must start with 5740)


Focus
A mathematical model is a formal simplified description of essential features of a system that allows for simulation and prediction of its output. Mathematical models include dynamical systems,  differential equations, game theoretic models, etc.
Mathematical models are widely used in the natural and social sciences and engineering providing a language for communications between mathematicians and physicists, engineers, computer scientists,  economists,  etc. Mathematical modeling usually refers to relatively new areas of applications of mathematical ideas.

In this course, we investigate models of various processes, such as species growth and interaction, epidemics, traffic flow, fair split, evolution, dynamics of unstable processes, a discrete chain of events,  metamaterials. The needed references must be found on the Internet or in the library. Example are computed using either Maple or any other platform such as Mathematica, MatLab, etc.

The class contains lectures and workshop-type presentations of projects by student groups. The grade is based on the presentations and reports, and on a couple of home work assignments.

Syllabus:  (preliminary)

Introduction (1 week)
Introduction to Math. Modeling. Non-uniqueness of math model.
The Greatest model -  Universe (from Ptolemy to Big Bang)
HW Problem: Divide the class into working groups
Populations dynamics 1. Single species (1 weeks)
Classical models, Discrete and continuous description. Equations with delay
Leslie model of reproduction and dynamics of World population.
Populations dynamics 2. Interacting species. (3 weeks)
Lotka-Volterra model, variations, interaction of several species.
Application to markets
Dynamics of epidemics
Evolutionary games
Migration; description by PDE.
Traffic flow (3 weeks)
Continuum model (Lighthill & Whitham and Richards),. Shock waves. Variations of the model
Discrete model. Cellular automata. Rule 184

Games and Fairness  (2 weeks)
Cooperative games: Fair shares (Shapley values)
Application to voting systems.
Unstable motion. (2 weeks)
Bouncing box
Avalanche
Nonlinear Waves (2 weeks)
Discrete Waves: Domino chain
Chain of masses the with bistable edges.
Metamaterials (3 weeks)
Auxetic materials
Morphing structures
Design of metamaterials


HW1 (due August 27)

1. Suggest an algorithm of forming groups of three for each project so that each student works with maximal number of classmates.
2. Learn to plot solutions of differential and difference equations using Maple or other platforms.

a) u'(t)= a u(t)- b u(t)^2, u(0)= 1,  t > 0;

b) u(n)= u(n-1) [1- u(n-2)], u(0)=0, u(1)=.1, n=0, 1, 2, ... 100.

c) Read from
A Mathematical Introduction to Population Dynamics
by Howie Weiss (Georgia Tech)
http://www.math.epn.edu.ec/emalca2010/files/material/Biomatematica/CUP101310.pdf
 http://www.math.epn.edu.ec/emalca2010/files/material/Biomatematica/CUP101310.pdf
ch 2    2.1-2.6


Maple code:
 
Solve and plot solutions to Difference eqns:

 
with(plots):
x[1] = 0.01;
for i to 100 do
 x[i+1] := (1+(1-(1/10)*x[i])*.15)*x[i]
end do;
pointplot({seq([n, x[n]], n = 1 .. 50)})

x[1] := 1;  x[2] := 1;
for i from 2 to 100 do
x[i+1] := (1+(1-(1/2)*x[i-1])*.5)*x[i]
end do;
pointplot({seq([n, x[n]], n = 1 .. 20)});

Plot solutions to Differential equations

with(DEtools);
LG := diff(y(t), t) = k*y(t)*(K-y(t));
K := 40; k := 0.01;
ivs := [y(0) = 1, y(0) = 10, y(0) = 50];

DEplot(LG, y(t), t = 0 .. 50, ivs);
DEplot(LG, y(t), t = 0 .. 50, y = 0 .. 60, ivs, arrows = medium, linecolor = black);

Or, you may first solve the differential equation
and then plot the solution:

de := dsolve({diff(z(t), t) = a*(1-c*z(t))*z(t), z(0) = zo});
p := eval(z(t), de); p0 := eval(p, {a = 1.3, c = .2, zo = .1});
plot(p0, t = 0 .. 8);


WH2 Leslie model, a group project, see the description and groups in Canvas class page.