5740-001 Math Modeling
Fall 2017

Class meets: W,   04:35PM-07:05PM    JTB 120
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 list)

Introduction (1 week)
Introduction to Math. Modeling. Non-uniqueness of math model.
The Greatest model -  Universe (from Ptolemy to Big Bang)
Problem: Divide the class into working groups
Populations dynamics 1. Single species (2 weeks)
Classical models, Equations with delay
Leslie model of reproduction
Populations dynamics 2. Interacting species. (2 weeks)
Lotka-Volterra model, variations, several species
Dynamics of epidemics
Fairness and evolution (2 weeks)
Cooperative games: Fair shares
Evolutionary games
Traffic flow (3 weeks)
Continuum model. Shock waves. Dissipation
Discrete model. Cellular automata. Rule 184
Unstable motion. (2 weeks)
Bouncing box
Avalanche
Repeated Motion. (2 weeks)
Discrete Waves: Domino chain
Chain with bistable links
Material models: Metamaterials (2 weeks)
Auxetic materials
Morphing structures


HW1

1. Suggest an algorithm of forming groups of three for each project so that each student works with maximal number of classmates.\

2. 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

3. Simulate and plot using Maple or any other platform
a. Logistic and Allee, Holling Type III growth, ( continuous  model)
b. Logistic, Logistic with delay (discrete model)

4. Show that in Holling Type III functional response (2.26). [p 24]
 point N=0 is always unstable.

Example of Maple code for plotting solutions to DE and discrete systems.

  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);


HW2.  Project.
Model population growth using Leslie model. Modify model accounting for habitat limiting capacity.
Suggested sources:
https://www.populationpyramid.net/world/2016/
https://en.wikipedia.org/wiki/Leslie_matrix
http://www.math.utah.edu/~cherk/teach/12mathmodel/leslie-model.pdf
https://en.wikipedia.org/wiki/Euler%E2%80%93Lotka_equation


HW3. From "Mathematical Introduction to Population Dynamics by Howie Weiss
http://www.math.epn.edu.ec/emalca2010/files/material/Biomatematica/CUP101310.pdf

1. Normalize the Lotka-Volterra model by scaling population sizes and time scale. Simulate dynamics of the normalized system for several values of the remaining parameter, graph the population density vs. time.

2.  Consider the normalized Lotka-Volterra model as in (3.41) (3.42)) with Holling-type responses of type II and type III, see section 2.4.3.  Find equilibrium points and comment, simulate and graph the population density vs. time. 

3. Problem 25. p. 54.  Consider the predator-prey system with a simple prey refuge  (eqs. (3.24) . (3.25))   How the equilibrium point is changed?  Linearize the problem near the equilibrium and comment on the change in the period depending on refuge size. Simulate the dynamics for several values of V, graph the population density vs. time.


HW4. Problems 17, 18, 19 p. 49