Analysis of small-angle scattering data, as well as novel precipitation measurements, are used to delineate the structure of the molecular aggregates that are formed when a fluid is injected into a porous medium to displace the in-place fluid. Our analysis suggests conclusively that these...

We report on a study of the Tehran Price Index (TEPIX) from 2001 to 2006 as an emerging market that has been affected by several political crises during the recent years, and analyze the non-Gaussian probability density function (PDF) of the log returns of the stocks' prices. We show that while...

Three distinct methods, namely, the spectral density, the multifractal random walk approach, and the multifractal detrended fluctuation analysis are utilized to study the properties of four distinct types of well logs from three oil and gas fields, namely, the natural gamma ray emission, neutron...

We propose a method for analyzing the data for the rates of exchange of various currencies versus the U.S. dollar. The method analyzes the return time series of the data as a Markov process, and develops an effective equation which reconstructs it. We find that the Markov time scale, i.e., the...

Modelling transport processes in a disordered system with broadly distributed heterogeneities, such as a field-scale porous medium, is often hampered by the fact that a very large set of equations (of the order of several millions) has to be solved repeatedly if detailed information about the...

We describe and discuss recent discrete models of brittle fracture in disordered media. By comparing the predictions of these models with the experimental data, we argue that such models can provide a rational explanation and quantitative predictions for many fracture properties of disordered...

The problem of a Pólya (unbiased, nearest-neighbor stepping) random walk is solved for several pseudo-lattices related to the Bethe lattice (Cayley tree). In each case, the solution is derived by projecting the walk on a pseudo-lattice onto a walk on a linear chain with internal states and a...

We report the results of extensive Monte Carlo simulations of a novel model of two-phase flow in porous media, recently proposed by us (Phys. Rev. Lett. 80 (1998) 3248), in which the two fluids act both as the invading as well as the defending fluids. The phenomenon is relevant to several...

We propose a discrete model for how opinions about a given “extreme” subject, about which various groups of a population have different degrees of enthusiasm for or susceptibility to, such as fanaticism, extreme social and political positions, and terrorism, may spread. The model, in a...

We study fluid invasion in porous media using a novel site-bond invasion percolation model. The defending fluid is incompressible, and therefore its trapping by the invading fluid is possible. We carry out flow calculations in order to simulate fluid invasion. The flow patterns indicate that the...