Fireflies • Hacker News Board

Re: Fireflies

#91

Post by mhb » Fri, Jun 02, 2017, 10:12 PM UTC

mhb wrote: post #58

JorgeGT wrote: post #54

Earlier quoted context omitted.

Exactly. For anyone having trouble, just picture a pure sinusoidal signal, flash = sin(2π·freq·time + phase). Fireflies are changing their phase, not their frequency. Completely independent parameters.

So the frequencies of the fireflies need to be pretty close to the same. How close are they actually?

No. The fireflies are able to adjust both their frequencies and phase differences. If their frequencies are matched they are phase-locked. If their phase difference is 0, then they are also synchronized.

From: https://www.math.hmc.edu/~dyong/math164/2006/runyeon/finalre...

Re: Fireflies

#92

Post by blacksmith_tb » Fri, Jun 02, 2017, 10:53 PM UTC

Faaak wrote: post #79

drueter wrote: post #16

Apologies for what might be shameless self-promotion, but if you're interested in this idea, you might like my 2012 project , "The Kuramoto Model (1,000 Fireflies)." I built 1,000 microcontroller-based LED devices that synchronized with each other using radio communication, with a similar algorithm to what Nicky used. Link is here: http://davidrueter.com/projects/2012-the-kuramoto-model.html

Very good result although the green mind in me screams a bit when thinking about all this waste.

Hmm, my city gives away bike lights pretty frequently - they aren't as sophisticated (sadly) but it doesn't seem especially wasteful either way (at least I'd assume that a fair percentage of the riders using them would have bought some kind of light otherwise; and as long as they continue to work, I wouldn't expect them to end up in a landfill). The synchronization is especially fun.

Re: Fireflies

#93

Post by 19eightyfour » Sat, Jun 03, 2017, 3:04 AM UTC

tsbertalan wrote: post #77

19eightyfour wrote: post #38

Nature has the best algorithms, don't it folks? I have a question about a detail. The rule is: 1. When you see a nearby neighbour flash, nudge your own clock forward. 2. That's it. My question is -- when the fireflies are firing at the same time, they see each other flash, so they all nudge their clocks forward, correct? Assuming they don't nudge their clocks forward at the same amount, they would fall out of sync, c…

At least in the Kuramoto model, it's a little more complicated than the OP makes it sound (but not much). Step 1 is more like "if you see a flash, bump your clock closer to midnight." Specifically, an ODE is given for firefly $i$'s phase angle $ \theta_i$ $$\dot\theta_i = \omega_i + K / N \sum_{j=1}^N \sin(\theta_j - \theta_i)$$ This gets interesting because the flies natural frequencies $\omega_i$ are also assumed t…

Jesus, that's such a great answer. Do you have an academic page people can look at for more of your writings or readings? Thanks so much!