S. N. Bose (1894-1974) and the Bose quantum statistics, a centennial tribute.
Safety regulations and fuzzy-logic control to nuclear reactors.
We present an R&D project on fuzzy-logic control applicatios tor the Belgian Nuclear Reactor 1 (BR1) at the Belgian Nuclear Research Centre (SCK·CEN). The project started in 1995 and aimed at investigating the added value of fuzzy logic control for nuclear reactors. We first review some relevant literature on fuzzy logic control in nuclear reactors, then present the state-of-the-art of the BR1 project, with an understanding of the safety requirements for this real fuzzy-logic control application...
Sampling 3-colourings of regular bipartite graphs.
Sampling the Fermi statistics and other conditional product measures
Through a Metropolis-like algorithm with single step computational cost of order one, we build a Markov chain that relaxes to the canonical Fermi statistics for k non-interacting particles among m energy levels. Uniformly over the temperature as well as the energy values and degeneracies of the energy levels we give an explicit upper bound with leading term km ln k for the mixing time of the dynamics. We obtain such construction and upper bound as a special case of a general result on (non-homogeneous)...
Scaling limit and cube-root fluctuations in SOS surfaces above a wall
Consider the classical -dimensional Solid-On-Solid model above a hard wall on an box of . The model describes a crystal surface by assigning a non-negative integer height to each site in the box and 0 heights to its boundary. The probability of a surface configuration is proportional to , where is the inverse-temperature and sums the absolute values of height differences between neighboring sites. We give a full description of the shape of the SOS surface for low enough temperatures....
Scaling limit of isoradial dimer models and the case of triangular quadri-tilings
Scaling limit of particle systems, incompressible Navier-Stokes equation and Boltzmann equation.
Scaling limit of the random walk among random traps on ℤd
Attributing a positive value τx to each x∈ℤd, we investigate a nearest-neighbour random walk which is reversible for the measure with weights (τx), often known as “Bouchaud’s trap model.” We assume that these weights are independent, identically distributed and non-integrable random variables (with polynomial tail), and that d≥5. We obtain the quenched subdiffusive scaling limit of the model, the limit being the fractional kinetics process. We begin our proof by expressing the random walk as the...
Scaling limits of anisotropic Hastings–Levitov clusters
We consider a variation of the standard Hastings–Levitov model HL(0), in which growth is anisotropic. Two natural scaling limits are established and we give precise descriptions of the effects of the anisotropy. We show that the limit shapes can be realised as Loewner hulls and that the evolution of harmonic measure on the cluster boundary can be described by the solution to a deterministic ordinary differential equation related to the Loewner equation. We also characterise the stochastic fluctuations...
Scaling of a random walk on a supercritical contact process
We prove a strong law of large numbers for a one-dimensional random walk in a dynamic random environment given by a supercritical contact process in equilibrium. The proof uses a coupling argument based on the observation that the random walk eventually gets trapped inside the union of space–time cones contained in the infection clusters generated by single infections. In the case where the local drifts of the random walk are smaller than the speed at which infection clusters grow, the random walk...
Scaling of Stochasticity in Dengue Hemorrhagic Fever Epidemics
In this paper we analyze the stochastic version of a minimalistic multi-strain model, which captures essential differences between primary and secondary infections in dengue fever epidemiology, and investigate the interplay between stochasticity, seasonality and import. The introduction of stochasticity is needed to explain the fluctuations observed in some of the available data sets, revealing a scenario where noise and complex deterministic skeleton...
Scattering theory for quantum dynamical semigroups. — II
Schrödinger operator with magnetic field in domain with corners
We present here a simplified version of results obtained with F. Alouges, M. Dauge, B. Helffer and G. Vial (cf [4, 7, 9]). We analyze the Schrödinger operator with magnetic field in an infinite sector. This study allows to determine accurate approximation of the low-lying eigenpairs of the Schrödinger operator in domains with corners. We complete this analysis with numerical experiments.
Search for different links with the same Jones' type polynomials: Ideas from graph theory and statistical mechanics
We describe in this talk three methods of constructing different links with the same Jones type invariant. All three can be thought as generalizations of mutation. The first combines the satellite construction with mutation. The second uses the notion of rotant, taken from the graph theory, the third, invented by Jones, transplants into knot theory the idea of the Yang-Baxter equation with the spectral parameter (idea employed by Baxter in the theory of solvable models in statistical mechanics)....
Second class particles in the rarefaction fan
Sectorial local non-determinism and the geometry of the Brownian sheet.
Segmentation of MRI data by means of nonlinear diffusion
The article focuses on the application of the segmentation algorithm based on the numerical solution of the Allen-Cahn non-linear diffusion partial differential equation. This equation is related to the motion of curves by mean curvature. It exhibits several suitable mathematical properties including stable solution profile. This allows the user to follow accurately the position of the segmentation curve by bringing it quickly to the vicinity of the segmented object and by approaching the details...
Self-avoiding walks on the lattice ℤ² with the 8-neighbourhood system
This paper deals with the properties of self-avoiding walks defined on the lattice with the 8-neighbourhood system. We compute the number of walks, bridges and mean-square displacement for N=1 through 13 (N is the number of steps of the self-avoiding walk). We also estimate the connective constant and critical exponents, and study finite memory and generating functions. We show applications of this kind of walk. In addition, we compute upper bounds for the number of walks and the connective constant....
Self-dual planar hypergraphs and exact bond percolation thresholds.
Selfgravitating systems in Newtonian theory - the Vlasov-Poisson system
We give a review of results on the initial value problem for the Vlasov--Poisson system, concentrating on the main ingredients in the proof of global existence of classical solutions.