We suppose that our observations can be decomposed into a fixed signal plus random noise, where the noise is modelled as a particular stationary Gaussian random field in N dimensional Euclidean space. The signal has the form of a known function centered at an unknown location and multiplied by an unknown amplitude, and we are primarily interested in a test to detect such a signal. There are man...

We investigate the effect of peculiar velocities on the redshift space distribution of z >∼ 2 galaxies, and we focus in particular on Lyα emitters. We generate catalogues of dark matter (DM) halos and identify emitters with halos of the same comoving space density (M(Lyα emitters) ≈ 3× 1011M⊙). We decompose the peculiar velocity field of halos into streaming, gradient and random components, and...

We elaborate on the link between state space models and (Gaussian) Markov random fields. We extend the Markov random field models by generalising the corresponding state space model. It turns out that several non Gaussian spatial models can be analysed by combining approximate Kalman filter techniques with importance sampling. We illustrate the ideas by formulating a model for edge detection in...

This paper proposes a novel statistical approach to intelligent document retrieval. It seeks to offer a more structured and extensible mathematical approach to the term generalization done in the popular Latent Semantic Analysis (LSA) approach to document indexing. A Markov Random Field (MRF) is presented that captures relationships between terms and documents as probabilistic dependence assump...

the permeability and tortuosity of pore-scale two and three-dimensional random porous media were calculated using the lattice boltzmann method (lbm). effects of geometrical parameters of medium on permeability and tortuosity were investigated as well. two major models of random porous media were reconstructed by computerized tomography method: randomly distributed rectangular obstacles in a uni...

In particle-in-cell (PIC) simulation, errors in space charge forces are of random character. It results in an unphysical increase of effective beam emittance, even while symplectic integrator is used. To establish quantitative measure of this effect on beam dynamics, an analytical model of equilibrium beam affected by random errors in space charge field calculations is considered. An explicit e...

We present real–space renormalization group (RG) calculations of the critical properties of the random–field Ising model on a cubic lattice in three dimensions. We calculate the RG flows in a two–parameter truncation of the Hamiltonian space. As predicted, the transition at finite randomness is controlled by a zero temperature, disordered critical fixed point, and we exhibit the universal cross...