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Lotfi Zekri

Publications and source records attributed to Lotfi Zekri.

7 recordsLinked to original sources
arXiv2013

Levy distributions of the currents intensities in metal dielectric systems

Levy distributions are involved in many physical phenomenon. The purpose of our study is to understand metal insulator transitions in composite systems using the above distributions. The exact method (EM) based on the calculation of Kirchhoff s equations solutions is used to compute currents intensities in each network division. Currents intensities distributions are studies for different widths of the system. We interpret these distributions in terms of Levy s law. Keywords: Levy distribution, percolation, composite materials, resistors network.

cond-mat.dis-nn↗
arXiv2008

Universal scaling of forest fire propagation

In this paper we use a variant of the Watts-Strogatz small-world model to predict wildfire behavior near the critical propagation/nonpropagation threshold. We find that forest fire patterns are fractal and that critical exponents are universal, which suggests that the propagation/nonpropagation transition is a second-order transition. Universality tells us that the characteristic critical behaviour of propagation in real (amorphous) forest landscapes can be extracted from the simplest network model.

physics.soc-ph↗
arXiv2005

Frequency dependent effective conductivity of two-dimensional metal-dielectric composites

We analyze a random resistor-inductor-capacitor $(RLC)$ lattice model of 2-dimensional metal-insulator composites. The results are compared with Bruggeman's and Landauer's Effective Medium Approximations where a discrepancy was observed for some frequency zones. Such a discrepancy is mainly caused by the strong conductivity fluctuations. Indeed, a two-branches distribution is observed for low frequencies. We show also by increasing the system size that at $p_c$ the so-called Drude peak vanishes; it increases for vanishing losses.

cond-mat.dis-nn↗
arXiv2004

Percolation and finite size scaling in seven dimensions

Numerical investigation of critical exponents on a hypercubic with L^d random sites with L up to $33 and d up to 7 show that above the critical dimension the phase transitions in Ising model and percolation are not alike.

cond-mat.dis-nn↗
arXiv2002

Modelization of the Impedance Spectroscopy of composites by Electrical Networks

We examined in this work the effect of the inter-grains distributions as well as the scaling of the complex impedance in order to analyze its frequency dependance for composite metal-insulator films. The dependance of the characteristic frequencies on the inter-grain distribution is shown for large sample sizes. The impedance spectra become statistically stable above sizes of the order 200x200.

cond-mat.dis-nn↗
arXiv2002

Vanishing Loss Effect on the Effective ac Conductivity behavior for 2D Composite Metal-Dielectric Films At The Percolation Threshold

We study the imaginary part of the effective $ac$ conductivity as well as its distribution probability for vanishing losses in 2D composites. This investigation showed that the effective medium theory provides only informations about the average conductivity, while its fluctuations which correspond to the field energy in this limit are neglected by this theory.

cond-mat.dis-nn↗