Quantifying the sensing power of vehicle fleets

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Monitoring urban environments is a challenging task; air pollution, road quality, congestion, and other quantities of interest vary widely across both time and space, requiring much effort to accurately monitor. A ‘drive-by’ approach to sensing could solve this problem. By attaching sensors to third party urban vehicles – like cars, taxis, buses or trucks – the spatiotemporal profile of a city could be scanned with great ease and accuracy. In this PNAS paper we analyze the ‘sensing power’ of taxis fleets in 9 major cities worldwide. We find an unexpectedly small number of taxis can scan a large portion of a city, verifying drive-by sensing can be readily implemented in the real world. See this video and this visualization for more info.

                   

Swarmalators: oscillators that sync and swarm

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Synchronization occurs in many natural and technological systems, from cardiac pacemaker cells to coupled lasers. In the synchronized state, the individual cells or lasers coordinate the timing of their oscillations, but they do not move through space. A complementary form of self-organization occurs among swarming insects, flocking birds, or schooling fish; now the individuals move through space, but without conspicuously altering their internal states.

Yet in some systems – such as groups of sperm, Japanese tree frogs, and colloidal suspensions of magnetic particles – self assembly and synchronization occur together. In this project, we investigate the co-action of these twin forms of self-orgnaization. You can find a fun demo here.

Swarmalators have also been realized in the lab: 2D & 3D

       

Pulse coupled oscillators

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During every heartbeat, thousands of pacemaker cells discharge all-at-once. This collective firing causes the contraction of cardiac muscles, which pumps blood around the body. Should these firing fall out of step, heartbeats can become erratic, inhibiting blood flow. In order to maintain healthy heart function, the pacemaker cells must therefore forever maintain their synchronous firing.

But how, precisely, do they do so? How do groups of cells stay organized enough to keep your heart beating? In this project, we try to figure this out – see this paper and this paper.