Random rein control

An interesting article in PLOS one explores the consequences of a system of random feedbacks: The Emergence of Environmental Homeostasis in Complex Ecosystems The Earth, with its core-driven magnetic field, convective mantle, mobile lid tectonics, oceans of liquid water, dynamic climate and abundant life is arguably the most complex system in the known universe. This … Continue reading “Random rein control”

Early warnings of catastrophe

There are warning signs when the active structure of a system is changing. But a new paper shows that they may not always be helpful for averting surprise catastrophes. Catastrophic Collapse Can Occur without Early Warning: Examples of Silent Catastrophes in Structured Ecological Models (PLOS ONE – open access) Catastrophic and sudden collapses of ecosystems … Continue reading “Early warnings of catastrophe”

Fun with 1D vector fields

Phase plots are the key to understanding life, the universe and the dynamics of everything. Well, maybe that’s a bit of an overstatement. But they do nicely explain tipping points and bifurcations, which explain a heck of a lot (as I’ll eventually get to). Fortunately, phase plots for simple systems are easy to work with. … Continue reading “Fun with 1D vector fields”

What the heck is a bifurcation?

A while back, Bruce Skarin asked for an explanation of the bifurcations in a nuclear core model. I can’t explain that model well enough to be meaningful, but I thought it might be useful to explain the concept of bifurcations more generally. A bifurcation is a change in the structure of a model that brings … Continue reading “What the heck is a bifurcation?”

A project power law experiment

Taking my own advice, I grabbed a simple project model and did a Monte Carlo experiment to see if project performance had a heavy tailed distribution in response to normal and uniform inputs. The model is the project tipping point model from Taylor, T. and Ford, D.N. Managing Tipping Point Dynamics in Complex Construction Projects … Continue reading “A project power law experiment”

Project Power Laws

An interesting paper finds a heavy-tailed (power law) distribution in IT project performance. IT projects fall in to a similar category. Calculating the risk associated with an IT project using the average cost overrun is like creating building standards using the average size of earthquakes. Both are bound to be inadequate. These dangers have yet … Continue reading “Project Power Laws”

The neo-cornucopians, live from planet Deepwater Horizon

On the heels of the 40th anniversary of Limits to Growth, the Breakthrough crowd is still pushing a technical miracle, just around the corner. Their latest editorial paints sustainability advocates as the bad guys: Stop and think for a moment about the basic elements of the planetary boundaries hypothesis: apocalyptic fears of the future, a professed … Continue reading “The neo-cornucopians, live from planet Deepwater Horizon”

Bifurcations from Strogatz’ Nonlinear Dynamics and Chaos

The following models are replicated from Steven Strogatz’ excellent text, Nonlinear Dynamics and Chaos. These are just a few of the many models in the text. They illustrate bifurcations in one-dimensional systems (saddle node, transcritical, pitchfork) and one two-dimensional system (Hopf). The pitchfork bifurcation is closely related to the cusp catastrophe in the climate model … Continue reading “Bifurcations from Strogatz’ Nonlinear Dynamics and Chaos”

Nuclear accident dynamics

There’s been a lot of wild speculation about the nuclear situation in Japan. Reporters were quick to start a “countdown to meltdown” based on only the sketchiest information about problems at plants, and then were quick to wonder if our troubles were over because the destruction of the containment structure at Fukushima I-1 didn’t breach … Continue reading “Nuclear accident dynamics”