Sajad Jafari

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Using the Routh–Hurwitz stability criterion and a systematic computer search, 23 simple chaotic flows with quadratic nonlinearities were found that have the unusual feature of having a coex-isting stable equilibrium point. Such systems belong to a newly introduced category of chaotic systems with hidden attractors that are important and potentially(More)
In this paper we introduce a new chaotic system and its corresponding circuit. This system has a special property of having a hidden attractor. Systems with hidden attractors are newly introduced and barely investigated. Conventional methods for parameter estimation in models of these systems have some limitations caused by sensitivity to initial(More)
In this letter we investigate the role of complex fixed-points in finding hidden attractors in chaotic flows with no equilibria. If these attractors could be found by starting the trajectory in the neighborhood of complex fixed-points, maybe it would be better not to call them hidden.
This paper introduces a new no–equilibrium chaotic system that is constructed by adding a tiny perturbation to a simple chaotic flow having a line equilibrium. Dynamics of the proposed system are investigated through Lyapunov exponents, bifurcation diagram, Poincaré map and period–doubling route to chaos. A circuit realization is also represented. Moreover,(More)
Dear Sir, Proper models help us to analyse and understand the behaviour of real systems, as well as to predict them in different situations. There are some parameters in each model that should be tuned in order to increase the similarity of the model to the real system as much as possible. In models of chaotic systems, changing these parameters not only(More)
Using the standard tight binding model of 2D graphite with short range electron repulsion, we predict a gapless spin-1, neutral collective mode branch below the particle-hole continuum with energy vanishing linearly with momenta at the Gamma and K points in the Brillouin zone. This spin-1 mode has a wide energy dispersion, 0 to approximately 2 eV, and is(More)
Employing the kernel polynomial method (KPM), we study the electronic properties of the graphene bilayers with Bernal stacking in the presence of diagonal disorder, within the tight-binding approximation and nearest neighbor interactions. The KPM method enables us to calculate local density of states (LDOS) without the need to exactly diagonalize the(More)
Modeling real-world systems plays a piv-otal role in their analysis and contributes to a better understanding of their behavior and performance. Classification, optimization , control, and pattern recognition problems rely heavily on modeling techniques. Such models can be categorized into three classes: white-box, black-box, and gray-box (Nelles, 2001).(More)
Retention of bacteriophages (phi 6, PR772, T1, and PP7) and mammalian viruses (poliovirus and influenza A virus) by a hydrophilic triple layer PVDF microporous membrane, the Ultipor VF grade DV50 membrane, was evaluated. Challenges of membrane discs or pleated filter cartridges were performed at concentrations of 10(6)-10(8) PFU/mL in one or more of the(More)