I did the short explainer in comment #409 above because I scrolled through the (infamous) Imperial College source code for modeling epidemics here as I wanted to get a feel for the complexity levels. Neil Ferguson of Imperial built his model on tho…
I think those are appropriate divisions:
Markov process modeling - purely stochastic : appropriate for formal classical mathematical analysis
Compartmental modeling - could be stochastic but also could be mean-value deterministic : more empirical,…
I have a comprehensive library of software functionality for modeling simulated robotics systems, with all the synchronization primitives supplied. The motivation was essentially building everything in a virtual reality environment before putting it…
Also active on Twitter, often with the category theory gang
Thinking about playing games on Petri nets pic.twitter.com/GhJwwOYlGF— julesh (@_julesh_) January 2, 2020
Algorithm for conventional tidal analysis:
Select N major tidal constituents, fixing the period for each but allowing amplitude and phase to vary
Create a linear superposition of the N constituents.
Iterate over training period the 2N amplitude+ph…
Being a veteran of threaded discussions, it's always useful to go to the source. David, In this thread you directed this question to me :
@WebHubTel Hi Paul, For the benefit of people who haven't read up on Petri nets / reaction networks, could …
"I do get your point, though, which can be boiled down to saying: what's the point of studying equilibrium solutions if the system is being driven by external forces, so there is no equilibrium."
Distinction perhaps between equilibrium and stea…
From my POV, the application roots are in complex robotics software and in OS's involving lots of parallel activities. Most of the fundamental computer science work was done by Dijkstra, Hoare, Dahl, and of course Petri in terms of communicating aut…
Autonomous versus non-autonomous equations. Lotka-Volterra belongs to the former category, a time-invariant system -- is that a stretch for describing real systems where populations depend on the environment? What good will that behavioral descript…
"could you say a few words about Lotka-Volterra"
I wrote something recently about L-V in an applied context here : https://geoenergymath.com/2020/03/29/lemming-fox-dynamics-not-lotka-volterra/
"Also, what specific classes of questions are …
I haven't kept close track over the years, but simulation software for Petri nets has many roots in reliability analysis and that's where I think you may find usable tools. The first hit I find on Google Scholar for "stochastic petri net" is for a …
David said:
"Wouldn't that call for exploring computational models of turbulence, rather than giving up?"
I think turbulence needs to be evaluated if and when it occurs. As I hinted, the Boeing fellow is looking for an excuse to marginalize th…
I attended several of the virtual EGU sessions and took notes and captured all my online comments here:
https://geoenergymath.com/2020/05/10/egu-2020-notes/
The topics I concentrated on were ENSO, QBO, Chandler wobble, and geophysical fluid dynami…
Among the armchair epidemiologists there seems to be a misguided belief that the factor (1 – 1/R0) will set the asymptote for "herd immunity" of a population. Any value of R0 above unity is exponential contagion growth and below unity it is damped. …
Thanks David,
I off-and-on get some feedback on these geophysical fluid dynamics models but occasionally get people that just rage. One PhD fellow that is considered an AGW skeptic and works for Boeing in wing design claims that it's pointless to do…
The role of dispersion as described in comment #11. A single set of equations without a stochastic spread is inadequate for projection.
"
One extra tidbit tonight:
Look at national & subnational daily deaths side-by-side.
NY daily deaths des…
Power-law growth of log-slope=2 is essentially a constant acceleration over time. For resource depletion, it's a fairly intuitive approach as one thinks of economic output in terms of a first-order linearly growing technology or a gradually growing…
Recent paper making the rounds:
"Strong correlations between power-law growth of COVID-19 in four continents and the inefficiency of soft quarantine strategies", Chaos
This is non-logistic growth. Power-law is essentially an acceleration over …
I presented to the International Conference on Learning Representations 2020 a few days ago. This workshop was on Integration of Deep Neural Models and Differential Equations. The math/physics applied is at the level of Hamiltonian and Lagrangian …
Placed the compartmental model mathematical analogy on the POB blog:
http://peakoilbarrel.com/the-oil-shock-model-and-compartmental-models/
received 360 comments so far, and many people get the idea.
"Flattening the curve" has almost opposite con…
Regarding #2 with mosquito netting, how it applies to masks when EVERYONE wears one
That's for an individual. If everyone wore *VERY BAD* masks, I guess the number of deaths would drop by a yuuuge factor, maybe 90%. Why? p is probability of infecti…
Jim, yes. Scientific blogs could be renamed public engineering notebooks.
"An engineering notebook is a book in which an engineer will formally document, in chronological
order, all of his/her work that is associated with a specific design pr…
https://medium.com/@frd.prost/technè-epistémè-et-praxis-sont-dans-un-bateau-1b6eb09ab05e
"The ethical imperatives in terms of knowledge building are for doctors to convey the conditions and results of their actions as precisely as possible. It i…
Haven't posted too much more as it really does appear that much of the predictive modeling involves aspects of game theory. In other words, high morbidity projections are used to convince the public to participate in mitigation procedures such as s…
David said:
.. which is to concentrate the content into larger "vertical threads."
Early on I tried creating a few spin-off threads but found quickly that it's difficult to keep track of the content. I have about 12 threads on ENSO (started i…
This is a google doc spreadsheet listing compartmental models for epidemic simulation
https://docs.google.com/spreadsheets/d/1hUZlVDPfa5C8KgURoP_3dAiUQgI6rdb7A5e_g8NcPaY/
There are many ways to simulate, the spreadsheet has columns for languages, …
One of the most challenging aspects of Lotka-Volterra is in applying it to real-world predator-prey observations. There is always a possibility that an underlying common-mode mechanism is controlling the population instead of non-linear feedback dyn…
From the Azimuth blog noticed that Graham Jones has started a group on ResearchGate
"Goal: Investigating methods which use a combination of genetic and epidemiological data to make inferences about the way that SARS-CoV-2 spreads and evolves. Th…
I pointed out that there is a way to derive precisely the logistic function via a stochastic spread in characteristics here:
https://forum.azimuthproject.org/discussion/comment/21938/#Comment_21938
This essentially says that an aggegration of sub-p…