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Introduction to the Modeling and Analysis of Complex Systems

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16.2. SIMULATING DYNAMICS ON NETWORKS 345import pycxsimula<strong>to</strong>rpycxsimula<strong>to</strong>r.GUI().start(func=[initialize, observe, update])Figure 16.8 shows a typical simulation run. The dynamics <strong>of</strong> this simulation can be bettervisualized if you increase <strong>the</strong> step size <strong>to</strong> 50. Run it yourself, <strong>and</strong> see how <strong>the</strong> inherentlydiverse nodes get self-organized <strong>to</strong> start a synchronized marching. Do you see any spatialpatterns <strong>the</strong>re?Figure 16.8: Visual output <strong>of</strong> Code 16.8. Time flows from left <strong>to</strong> right.Exercise 16.8 It is known that <strong>the</strong> level <strong>of</strong> synchronization in <strong>the</strong> Kuramo<strong>to</strong> model(<strong>and</strong> many o<strong>the</strong>r coupled oscilla<strong>to</strong>r models) can be characterized by <strong>the</strong> followingmeasurement (called phase coherence):1 ∑r =e iθ i(16.13)∣n∣iHere n is <strong>the</strong> number <strong>of</strong> nodes, θ i is <strong>the</strong> state <strong>of</strong> node i, <strong>and</strong> i is <strong>the</strong> imaginaryunit (<strong>to</strong> avoid confusion with node index i). This measurement becomes 1 if all <strong>the</strong>nodes are in perfect synchronization, or 0 if <strong>the</strong>ir phases are completely r<strong>and</strong>om<strong>and</strong> uniformly distributed in <strong>the</strong> angular space. Revise <strong>the</strong> simulation code sothat you can measure <strong>and</strong> moni<strong>to</strong>r how this phase coherence changes during <strong>the</strong>simulation.Exercise 16.9<strong>to</strong>pologies:Simulate <strong>the</strong> Kuramo<strong>to</strong> model on each <strong>of</strong> <strong>the</strong> following network

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