Old models are the models previously featured on the old Physics of Risk website (which is still available at http://mokslasplius.itpa.lt/rizikos-fizika (note that all of its content is available only in Lithuanian)). Note that old models might not necessarily be identical to the corresponding models on the old website, they might be a completely new pieces of software, yet considering the topic tackled on the old website.
Recently I have discovered an online education system Coursera. While browsing through the available courses I noticed one named “Social and Economic Networks: Models and Analysis”. Sadly it was already six weeks into the eight week program, so I was not able to formally complete it. Yet the knowledge I have obtained by viewing videos of this course enabled me to prepare couple of posts for this website.
Belousov-Zhabotinsky reaction  is a chemical reaction, or more precisely a reaction family, known for exhibiting temporal and spatial oscillations.
This reaction is one of the classical examples of the natural non-linear oscillations. Another prominent example is the previously analyzed prey-predator interactions in the ecosystem. Interestingly enough despite being of a very different nature both of these example can be modeled using Lotka-Volterra equations.
Here, on the Physics of Risk, we frequently talk about two essential statistical features of the time series – probability and spectral densities. The probability density function should well known to our readers – it is related to the distribution of time series values. On the Physics of Risk we have also a Lithuanian-only article on this topic (see it here). So the time has come to discuss the power spectral density. Continue reading “Power spectral density (part 1)” »
Previously on Physics of Risk we have wrote about Lotka-Volterra equations. At that time we didn’t provide an interactive applet with the text. Only recently we have updated the text and provided an interactive Wolfram CDF applet. This applet was replaced by HTML5 app, yet it is still available for download.
In classical physics differential equations is the main tool to mathematically describe dynamical systems. Having obtained the mathematical descriptions of the system we should be able to predict the evolution of the system. It is noted that the evolution of the classical systems is pretty trivial – no matter what the initial condition is the system will “find” the stable state. Usually dissipative forces (such as frictions) are to be blamed for this. Though not all systems are so simple… Continue reading “Randomly generated strange attractors” »