S. Ziti

Pair-dependent rejection rate and its impact on traffic flow in a scale-free network

In this paper, we propose a pair-dependent rejection rate of packet information between routers in the framework of the minimal traffic model applied to scale-free networks. We have shown that the behavior of the transition point from the phase where the system balances the inflow of new information packets with successful delivery of the old ones to the congested phase depends on the underlying mechanism of packet rejection. It is possible to achieve larger values for the critical load by varying the rejection of the packets issued from a given node by its neighbors. We have proposed an asymmetric protocol, where we found the existence of a whole interval where the packet rejection is strongly beneficial to the overall performance of the system. We have also shown that for the dynamic protocol, the transition point is shifted toward higher values permitting the network to handle more traffic load, despite the fact that the critical load decreases when increasing the rejection parameter.

Wetting and layering transitions in a nano-dendrimer PAMAM structure: Monte Carlo study

This study is based on a nano-model of the dendrimer polyamidoamine (PAMAM). The idea is to examine the magnetic properties of such models in the context of wetting and the layering transitions. The studied system consists of spins Ising ferromagnetic in real nanostructure found in different scientific domains. To study this system, we perform Monte Carlo simulations leading to interesting results recapitulated in two classes. The former is the ground state phase diagrams study. The latter is the magnetic properties at non null temperatures. Also, we analyzed the effect of the terms present in the Hamiltonian governing our system such as the external magnetic field and the exchange couplings interactions.

Magnetic properties of a Lie symmetry double square nanostructure: Monte Carlo study

Abstract Inspired by Lie symmetries and motivated by the existence of the double hexagonal geometry in the two-dimensional material physics, we study a nanosystem based on the double square structure, which we refer as the B2 nanostructure, known as SO(5) Lie algebra. This structure involves two squares of unequal side lengths rotated by angle 45°. The model contains eight atoms instead of four ones appearing in the single square structure. The number of atoms is identified with the non- null roots of the B2 Lie algebra. In particular, we propose a nanolattice model consisting of particles with and S = 1 spins, consisting of two and three states, respectively. Theses spins are placed at the double square sites producing a new geometry formed by and (1×1) structures. More precisely, we study the effect of σ–σ and σ–S coupling exchange interactions. This investigation is made in terms of both external and crystal magnetic fields. First, we elaborate analytically the corresponding ground-state phase diagrams. Second, we investigate the magnetic properties using Monte Carlo method.