Eugène Pechersky

Detection of linear features in SAR images: application to road network extraction

The authors propose a two-step algorithm for almost unsupervised detection of linear structures, in particular, main axes in road networks, as seen in synthetic aperture radar (SAR) images. The first step is local and is used to extract linear features from the speckle radar image, which are treated as road-segment candidates. The authors present two local line detectors as well as a method for fusing information from these detectors. In the second global step, they identify the real roads among the segment candidates by defining a Markov random field (MRF) on a set of segments, which introduces contextual knowledge about the shape of road objects. The influence of the parameters on the road detection is studied and results are presented for various real radar images.

A slow-to-start traffic model related to a M/M/1 queue

We consider a system of ordered cars moving in from right to left. Each car is represented by a point in ; two or more cars can occupy the same point but cannot overpass. Cars have two possible velocities: either 0 or 1. An unblocked car needs an exponential random time of mean 1 to pass from speed 0 to speed 1 (slow-to-start). Car i, say, travels at speed 1 until it (possibly) hits the stopped car i−1 to its left. After the departure of car i−1, car i waits an exponential random time to change its speed to 1, travels at this speed until it hits again stopped car i−1 and so on. Initially cars are distributed in according to a Poisson process of parameter λ<1. We show that every car will be stopped only a finite number of times and that the final relative car positions are again a Poisson process with parameter λ. To do that, we relate the trajectories of the cars to an M/M/1 stationary queue as follows. Space in the traffic model is time for the queue. The initial positions of the cars coincide with the arrival process of the queue and the final relative car positions match the departure process of the queue.

Phase Transition in Ferromagnetic Ising Model with a Cell-Board External Field

We show the presence of a first-order phase transition for a ferromagnetic Ising model on

Percolation Properties of the Non-ideal Gas

\mathbb {Z}^2

Gibbs random graphs on point processes

Z2 with a periodical external magnetic field. The external field takes two values h and

Large fluctuations of radiation in stochastically activated two-level systems

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