83 research outputs found
Random Walks Estimate Land Value
Expected urban population doubling calls for a compelling theory of the city.
Random walks and diffusions defined on spatial city graphs spot hidden areas of
geographical isolation in the urban landscape going downhill. First--passage
time to a place correlates with assessed value of land in that. The method
accounting the average number of random turns at junctions on the way to reach
any particular place in the city from various starting points could be used to
identify isolated neighborhoods in big cities with a complex web of roads,
walkways and public transport systems
Ghetto of Venice: Access to the Target Node and the Random Target Access Time
Random walks defined on undirected graphs assign the absolute scores to all
nodes based on the quality of path they provide for random walkers. In city
space syntax, the notion of segregation acquires a statistical interpretation
with respect to random walks. We analyze the spatial network of Venetian canals
and detect its most segregated part which can be identified with canals
adjacent to the Ghetto of Venice.Comment: 14 pages, 3 figure
Intelligibility and First Passage Times In Complex Urban Networks
Topology of urban environments can be represented by means of graphs. We
explore the graph representations of several compact urban patterns by random
walks. The expected time of recurrence and the expected first passage time to a
node scales apparently linearly in all urban patterns we have studied In space
syntax theory, a positive relation between the local property of a node
(qualified by connectivity or by the recurrence time) and the global property
of the node (estimated in our approach by the first passage time to it) is
known as intelligibility. Our approach based on random walks allows to extend
the notion of intelligibility onto the entire domain of complex networks and
graph theory.Comment: 19 pages, 4 figures, English UK, the Harvard style reference
Stochastic and Discrete Time Models of Long-Range Turbulent Transport in the Scrape-Off Layer
Two dimensional stochastic time model of scrape-off layer (SOL) turbulent
transport is studied. Instability arisen in the system with respect to the
stochastic perturbations of both either density or vorticity reveals itself in
the strong outward bursts of particle density propagating ballistically across
the SOL. The stability and possible stabilization of the cross- field turbulent
system depend very much upon the reciprocal correlation time between density
and vorticity fluctuations. Pdf of the particle flux for the large magnitudes
of flux events can be modelled with a simple discrete time toy model of random
walks concluding at a boundary. The spectra of wandering times feature the pdf
of particle flux in the model and qualitatively reproduce the experimental
statistics of transport events.Comment: 21 pages,11 figure
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