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Stage 1: Modelling the growth of a single tree

Thu, 28/02/2008 - 18:23 — administrator
Step 1
Add a compartment to the desktop, and rename it size.
Step 2
Draw a flow into the size compartment, and rename it growth.

Individual-based modelling of a population of trees

Thu, 28/02/2008 - 18:21 — administrator

Introduction

The main aim of this tutorial is to introduce you to individual-based modelling.

System Dynamics (or “compartment-flow”) modelling generally does not represent individuals in a population. Instead, all the individuals are lumped together and represented by a single value: the number of individuals in a population, the total weight of all the individuals, or the total amount of some substance they contain (water, carbon or nitrogen, for example).

Stage 4: Sketching biologically meaningful relationships

Thu, 28/02/2008 - 17:34 — administrator

What we now have are some variables in our model ( and ) for introducing biologically-meaningful relationships. The influence arrows we have drawn to these two variables expresses the biologically-reasonable assumptions that:

Stage 3: Re-casting the model diagram

Thu, 28/02/2008 - 17:32 — administrator

The present model is based on a number of assumptions that are biologically unsound. For example, it assumes that the number of rabbits eaten per fox is directly proportional to the number of rabbits, so doubling the number of rabbits doubles the number eaten per fox — even if there are millions of rabbits around!

Stage 2: Adding in predator dynamics

Thu, 28/02/2008 - 17:11 — administrator
Step 1
Add a  flow into the foxes compartment, and rename it fox repro.
Step 2

Stage 1: Modelling the dynamics of a single population

Thu, 28/02/2008 - 17:09 — administrator
Step 1
Add two  compartments to the desktop, and rename them rabbits and foxes
Step 2

Modelling predator-prey interactions

Thu, 28/02/2008 - 16:38 — administrator

Introduction

The classic, textbook predator-prey model is that proposed by Lotka and Volterra in 1927. In words, the model states that:

Page type: 
Tutorial

Editing an issue detaches it from it's project

Thu, 28/02/2008 - 11:54 — jonathanm

Editing an issue detaches it from it's project. A nonsense pid value is assigned.

Drupal issue: project* namespace bugs in $node

Reporter: 
jonathanm
Created: 
Thu, 28/02/2008 - 11:54
Updated: 
Mon, 28/04/2008 - 09:54

Some project issues records have become separated from their project

Thu, 28/02/2008 - 10:44 — jonathanm

Some project issues records have become separated from their project.

Probably an error during and update though there were no error reports.

-- Jonathan

The pid (project id) fields had nonsense values in them, i.e. values not in the projects_projects table. All should have been in the simulisticscomcore project (only two other issues anyway).

Used myphpadmin to edit the tables by hand.

Reporter: 
jonathanm
Created: 
Thu, 28/02/2008 - 10:44
Updated: 
Tue, 04/03/2008 - 11:28

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