Publications Internationnales

2021
Melkemi O, Saibi K, Mokhtari Z. Weighted variable Hardy spaces on domains. Advances in Operator Theory [Internet]. 2021;6 (56). Publisher's VersionAbstract

In this paper, we introduce and study the weighted variable Hardy space on
domains. We prove the atomic decompositions of this space, and as application, we
figure out its dual space.

2020
Ghegal S, Hamchi I, Messaoudi SA. Global existence and stability of a nonlinear wave equation with variable-exponent nonlinearities. Applicable Analysis [Internet]. 2020;99 (8) :1333-1343. Publisher's VersionAbstract

In this paper, we consider a nonlinear wave equation with damping and source terms of variable-exponent types. First, we use the stable-set method to prove a global result. Then, by applying an integral inequality due to Komornik, we obtain the stability result.

Brahimi M, Melkemi K, Boussaad A. Design of nonstationary wavelets through thepositive solution of Bezout's equation. Journal of Interdisciplinary Mathematics [Internet]. 2020;24 (3) :1-13 . Publisher's VersionAbstract

In this paper, we present a new technique for constructing a nonstationary wavelet. The key idea relies on the following: for each wavelet level, we solve the Bezout’s equation and we propose a positive solution over the interval [–1, 1]. Using the Bernstein’s polynomials we approximate this proposed positive solution with the intention to perform a spectral factorization.

Bouhoufani O, Hamchi I. Coupled System of Nonlinear HyperbolicEquations with Variable-Exponents: GlobalExistence and Stability. Mediterr. J. Math [Internet]. 2020;17 (166). Publisher's VersionAbstract

In this paper, we consider a coupled system of two nonlinear
hyperbolic equations with variable-exponents in the damping and source
terms. Under suitable assumptions on the intial data and the variable
exponents, we prove a global existence theorem, using the Stable-set
method. Then, we establish a decay estimate of the solution energy, by
Komornik’s integral approach.

Hanachi A, HOUAMED HAROUNE, Zerguine M. ON THE GLOBAL WELL-POSEDNESS OF THEAXISYMMETRIC VISCOUS BOUSSINESQ SYSTEM INCRITICAL LEBESGUE SPACES. DISCRETE AND CONTINUOUS DYNAMICAL SYSTEMS [Internet]. 2020;40 (11) : 6473-6506. Publisher's VersionAbstract

The contribution of this paper will be focused on the global existence and uniqueness topic in three-dimensional case of the axisymmetric viscous Boussinesq system in critical Lebesgue spaces. We aim at deriving analogous results for the classical two-dimensional and three-dimensional axisymmetric Navier-Stokes equations recently obtained in [19, 20]. Roughly speaking, we show essentially that if the initial data (v0; ρ0) is axisymmetric
and (!0; ρ0) belongs to the critical space L1(Ω) ×L1(R3), with !0 is the initial
vorticity associated to v0 and Ω = f(r; z) 2 R2 : r > 0g, then the viscous
Boussinesq system has a unique global solution.

2019
Djeddi A, Dib D, Azar A-T, Abdelmalek S. Fractional Order Unknown Inputs Fuzzy Observer for Takagi–Sugeno Systems with Unmeasurable Premise Variables. Mathematics [Internet]. 2019;7 (10). Publisher's VersionAbstract

This paper presents a new procedure for designing a fractional order unknown input observer (FOUIO) for nonlinear systems represented by a fractional-order Takagi–Sugeno (FOTS) model with unmeasurable premise variables (UPV). Most of the current research on fractional order systems considers models using measurable premise variables (MPV) and therefore cannot be utilized when premise variables are not measurable. The concept of the proposed is to model the FOTS with UPV into an uncertain FOTS model by presenting the estimated state in the model. First, the fractional-order extension of Lyapunov theory is used to investigate the convergence conditions of the FOUIO, and the linear matrix inequalities (LMIs) provide the stability condition. Secondly, performances of the proposed FOUIO are improved by the reduction of bounded external disturbances. Finally, an example is provided to clarify the proposed method. The obtained results show that a good convergence of the outputs and the state estimation errors were observed using the new proposed FOUIO.

Meddour H. LOCAL PERSISTENCE OF GEOMETRIC STRUCTURES FOR BOUSSINESQ SYSTEM WITH ZERO VISCOSITY. [Internet]. 2019;71 (4) :285-303. Publisher's VersionAbstract

The current paper deals with the local well-posedness problem for the twodimensional partial viscous Boussinesq system when the initial vorticity belongs to the patch class. We prove in particular some results concerning the regularity persistence of the patch boundary and establish the convergence towards the inviscid limit when the molecular diffusivity goes to zero. 

Bounibane B, Djeffal E-A. Kernel function-based interior-point algorithms for linear optimisation. International Journal of Mathematical Modelling and Numerical Optimisation [Internet]. 2019;9 (2) :158. Publisher's VersionAbstract

We propose a primal-dual interior-point algorithm for linear optimisation based on a class of kernel functions which is eligible. New search directions and proximity measures are defined based on these functions. We derive the complexity bounds for large and small-update methods respectively. These are currently the best known complexity results for such methods.

2017
Touil A, Youkana A. Boundedness and asymptotic behavior of solutions for a diffusive epidemic model. Mathematical Methods in the Applied Sciences [Internet]. 2017;40 (4) :970-978. Publisher's VersionAbstract

The aim of this paper is to study the existence and the asymptotic behavior of solutions for some reaction–diffusion equations arising in epidemic biology phenomena. We will show that for a rather broad class of nonlinearities, the solutions are global and uniformly bounded, and under suitable assumptions on the parameters of the system, these solutions converge as time goes to infinity to a disease-free equilibrium point.

Ouannas A, Abdelmalek S, Bendoukha S. Coexistence of some chaos synchronization types in fractional-order differential equations. Electronic Journal of Differential Equations [Internet]. 2017;128 :1-15. Publisher's VersionAbstract

Referring to incommensurate and commensurate fractional systems, this article presents a new approach to investigate the coexistence of some synchronization types between non-identical systems characterized by different dimensions and different orders. In particular, the paper shows that complete synchronization (CS), anti-synchronization (AS) and inverse full state hybrid function projective synchronization (IFSHFPS) coexist when synchronizing a three-dimensional master system with a four-dimensional slave system. The approach is based on two new results involving stability theory of linear fractional systems and the fractional Lyapunov method. A number of examples are provided to highlight the applicability of the method.

Dehda B, Melkemi K. Image denoising using new wavelet thresholding function. Journal of Applied Mathematics and Computational Mechanics [Internet]. 2017;16 (2) :55-65. Publisher's VersionAbstract

In this paper, we propose a new image denoising method based on wavelet thresholding In this method , we introduce a new nonlinear thresholding function characterized by a shape parameter and basic properties These characteristics make the new method able to achieve a compromise between both traditional thresholding techniques such as Hard and Soft thresholding The experimental results show that our proposed method provides better performance compared to many classical thresholding methods in terms of the visual quality of the denoised image.

Abdesselam N, Melkemi K. Memory boundary feedback stabilization for Schrödinger equations with variable coefficients. Electronic Journal of Differential Equations [Internet]. 2017;129 :1-14. Publisher's VersionAbstract

First we consider the boundary stabilization of Schrödinger equations with constant coefficient memory feedback. This is done by using Riemannian geometry methods and the multipliers technique. Then we explore the stabilization limits of Schrödinger equations whose elliptical part has a variable coefficient. We established the exponential decay of solutions using the multipliers techniques. The introduction of dissipative boundary conditions of memory type allowed us to obtain an accurate estimate on the uniform rate of decay of the energy for Schrödinger equations.

2016
Djeffal E-A, Djeffal L. A path following interior-point algorithm for semidefinite optimization problem based on new kernel function. Journal of Mathematical Modeling [Internet]. 2016;4 (1) :35-58. Publisher's Version
2012
Abdelmalek S, Louafi H, Youkana A. EXISTENCE OF GLOBAL SOLUTIONS FOR A GIERER-MEINHARDT SYSTEM WITH THREE EQUATIONS. Electronic Journal of Differential Equations [Internet]. 2012;2012 (50) :1–8. Publisher's VersionAbstract

This articles shows the existence of global solutions for a GiererMeinhardt model of three substances described by reaction-diffusion equations with fractional reactions. Our technique is based on a suitable Lyapunov functional.