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EXISTENCE OF SOLUTIONS FOR GRADIENT SYSTEMS WITH APPLICATION TO DIFFUSION PROBLEMS INVOLVING NONCONVEX ENERGIES

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Acta Mathematica Scientia 2018年第6期38卷 1767-1778页

作者： Sahbi BOUSSANDEL Dpartement de Mathmatiques Facult des Sciences de Bizerte

In this paper, we establish the existence of solutions for gradient systems ofevolution under some type （M） and semi-coerciveness conditions. The main result is appliedin order to solve nonlinear diffusion equations... 详细信息

关键词： gradient systems existence of solutions Galerkin method type (M) condition semi-coerciveness diffusion equations

New materials based on carbazole for optoelectronic device applications:Theoretical investigation

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Chinese Chemical Letters 2008年第4期19卷 488-492页

作者： K.Hasnaoui H.Zgou M.Hamidi M.Bouachrine Unité de Recherche sur les Macromolécules et Modélisation Faculté des Sciences et TechniquesB.P.509 Boutalamine5200 ErrachidiaMorocco Unité de Chimie Théorique AppiquéeFaculté des Sciences et TechniquesB.P.509 Boutalamine5200 ErrachidiaMorocco Unité de Chimie Théorique Appliquée Faculté des Sciences et TechniquesB.P.509 Boutalamine5200 ErrachidiaMorocco Unité de Recherche sur les Macromolécules et Modélisation Faculté des Sciences et TechniquesB.P.509 Boutalamine5200 ErrachidiaMorocco

A quantum-chemical investigation on the structural and optoelectronic properties of two materials based on carbazole is carried *** purpose is to display the effect of grafting the fluorine atoms on their optoelectronic and physico-chemical *** addition to solubility in the polar solvents and the modification in geometric parameters,the substitution of fluorine destabilizes the HOMO and LUMO levels,decreases the band gap energy and raises conjugation *** properties suggest the substituted fluorine compound as a good candidate for optoelectronic applications.

关键词： Conjugated polymers DFT theoretical investigation Carbazole Optoelectronic applications

First-principles study of the electronic structure of a superstoichiometric rare earth dihydride GdH2.25

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Journal of Rare Earths 2016年第1期34卷 66-70页

作者： z.ayat a.boukraa b.daoudi Univ Ouargla Fac. Des Mathematiques et des Sciences de la Matidre Lab. Developpement des energies nouvelles et renouvelables dans les zones arides et sahariennes Ouargla 30000 Algeria

We performed ab initio calculations of electronic structure and equilibrium properties for the rare earth superstoichiometric dihydride GdH2.25 （with the space group Pm-3m （No. 221）） using the full-potential linearized augmented plane wave method （FP-LAPW） approach within the density functional theory （DFT） in the generalized gradient approximation （GGA） and local density approximation （LDA） as implemented in the WIEN2k simulation code at 0 K. The equilibrium properties were determined, the density of states, electronic density and the energy band structures were studied in details. It was concluded that the GGA optimized lattice parameter agreed much better with the experimental findings than the LDA one, The non negligible electronic density of states at the Fermi level confirmed that the GdH2.25 had a metallic character. The Fermi energy EF fell at a level where most of the states were rare-earth 5d-eg conduction states while negligible contributions of both interstitial （tetrahedral and octahedral） H s-states were observed near EF, From electronic density, the bonding between Gd and tetrahedral H atoms was of prominent covalency, while was ionic between Gd and octahedral H atoms.

关键词： rare-earth dihydrides GdU2.25 density functional theory ab initio calculations WIEN2k

An investigation of merging and diverging cars on a multi-lane road using a cellular automation model

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Chinese Physics B 2012年第11期21卷 565-572页

作者： K.Jetto H.Ez-Zahraouy A.Benyoussef Laboratoire de Magnétisme et de la Physique des Hautes Energies Universit'e Mohammed V Faculté des Sciences Ecole Hassania des Travaux Publics KM 7 Route DEL JADIDAB.P 8108OasisCasablancaMaroc

In this paper, we have investigated two observed situations in a multi-lane road. The first one concerns a fast merging vehicle. The second situation is related to the case of a fast vehicle leaving the fastest lane back into the slowest lane and targeting a specific way out. We are interested in the relaxation time T, i.e., which is the time that the merging （diverging） vehicle spends before reaching the desired lane. Using analytical treatment and numerical simulations for the NaSch model, we have found two states, namely, the free state in which the merging （diverging） vehicle reaches the desired lane, and the trapped state in which T diverges. We have established phase diagrams for several values of the braking probability. In the second situation, we have shown that diverging from the fast lane targeting a specific way out is not a simple task. Even if the diverging vehicle is in the free phase, two different states can be distinguished. One is the critical state, in which the diverging car can probably reach the desired way out. The other is the safe state, in which the diverging car can surely reach the desired way out. In order to be in the safe state, we have found that the driver of the diverging car must know the critical distance （below which the way out will be out of his reach） in each lane. Furthermore, this critical distance depends on the density of cars, and it follows an exponential law.

关键词： traffic flow merging and diverging area intelligent transportation system cellular au-tomation

Theoretical study of structural and electronic properties of oligo(thiophene-phenylene)s in comparison with oligothiophenes and oligophenylenes

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Chinese Chemical Letters 2008年第1期19卷 123-126页

作者： H.Zgou S.M.Bouzzine S.Bouzakraoui M.Hamidi M.Bouachrine Unité de Recherche sur les Macromolécules et Modélisation Faculté des Sciences et TechniquesB.P.509 Boutalamine5200 ErrachidiaMorocco Unité de Chimie Théorique AppliquéeFaculté des Sciences et TechniquesB.P.509 Boutalamine5200 ErrachidiaMorocco Unité de Chimie Théorique Appliquée Faculté des Sciences et TechniquesB.P.509 Boutalamine5200 ErrachidiaMorocco Unité de Recherche sur les Macromolécules et Modélisation Faculté des Sciences et TechniquesB.P.509 Boutalamine5200 ErrachidiaMorocco

In this work, a quantum-chemical investigation on the structural and opto-electronic properties of oligo（thiophene-phenylene）（4TP） is carried out. The results are discussed in comparison with the properties of corresponding oligothiophene （8T） and oligophenylene （8P）. As the opto-electronic properties of this type of conducting polymers are governed by their electronic band gap, we shall also present a comparison among HOMO, LUMO and band gap energies of these three materials.

关键词： Conjugated polymers Oligothiophene Oligophenylene Oligo(thiophene-phenylene) DFT

Monte Carlo study of nanowire magnetic properties

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Chinese Physics B 2013年第5期22卷 514-518页

作者： R. Masrour L. Bahmad A. Benyoussef Laboratoire de Magnétisme et Physique des Hautes Energies URAC 12Université Mohammed V-AgdalFaculté des Sciences Laboratory of Materials ProcessEnvironment and QualityCady Ayyad UniversityNational School of Applied Sciences

In this work, we use Monte Carlo simulations to study the magnetic properties of a nanowire system based on a honeycomb lattice, in the absence as well as in the presence of both an external magnetic field and crystal field. The system is formed with NL layers having spins that can take the values σ= ± 1/2 and S =±1,0. The blocking temperature is deduced, for each spin configuration, depending on the crystal field A. The effect of the exchange interaction coupling Jp between the spin configurations σ and S is studied for different values of temperature at fixed crystal field. The established ground-state phase diagram, in the plane （Jp, △）, shows that the only stable configurations are：（1/2,0）, （1/2, ＋1）, and （1/2,- 1）. The thermal magnetization and susceptibility are investigated for the two spin configurations, in the absence as well as in the presence of a crystal field. Finally, we establish the hysteresis cycle for different temperature values, showing that there is almost no remaining magnetization in the absence of the external magnetic field, and that the studied system exhibits a super-paramagnetic behavior.

关键词： Monte Carlo simulations nanowire magnetic field crystal field

On the Equivalence of Weyl Theorem and Generalized Weyl Theorem

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Acta Mathematica Sinica,English Series 2007年第1期23卷 103-110页

作者： M.BERKANI Grouped'Analyse et Théorie des Opérateurs(G.A.T.O.) Département de MathématiquesUniversitéMohammed ⅠFaculté des SciencesOujda 60000Morocco

We know that an operator T acting on a Banach space satisfying generalized Weyl＇s theorem also satisfies Weyl＇s theorem. Conversely we show that if all isolated eigenvalues of T are poles of its resolvent and if T satisfies Weyl＇s theorem, then it also satisfies generalized Weyl＇s theorem. We give also a sinlilar result for the equivalence of a-Weyl＇s theorem and generalized a-Weyl＇s theorem. Using these results, we study the case of polaroid operators, and in particular paranormal operators.

关键词： B-Fredholm operator Weyl's theorem generalized Weyl's theorem a-Weyl's theorem,generalized a-Weyl's theorem poles

Dynamics of high-frequency modulated waves in a nonlinear dissipative continuous bi-inductance network

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Chinese Physics B 2021年第6期30卷 193-205页

作者： S M Ngounou F B Pelap Unitéde Recherche de Mécanique et de Modélisation des Systèmes Physiques(UR-2 MSP) Facultédes SciencesUniversitéde DschangBP 69 DschangCameroun Unitéde Recherche de Matière Condensée d'Electronique et de Traitement du Signal(UR-MACetS) Facultédes SciencesUniversitéde DschangBP 67 DschangCameroun

This paper presents intensive investigation of dynamics of high frequency nonlinear modulated excitations in a damped bimodal lattice. The effects of the dissipation are considered through a linear dissipation coefficient whose evolution in terms of the carrier wave frequency is checked. There appears that the dissipation coefficient increases with the carrier wave frequency. In the linear limit and for high frequency waves, study of the asymptotic behavior of plane waves reveals the existence of two additional regions in the dispersion curve where the modulational phenomenon is observed compared to the lossless line. Based on the multiple scales method exploited in the continuum approximation using an appropriate decoupling ansatz for the voltage of the two different cells, it appears that the motion of modulated waves is described by a dissipative complex Ginzburg–Landau equation instead of a Korteweg–de Vries equation. We also show that this amplitude wave equation admits envelope and hole solitons in the high frequency mode. From basic sources, we design a programmable electronic generator of complex signals with desired characteristics, which delivers signals exploited as input waves for all our numerical simulations. These simulations are performed in the LTspice software that uses realistic components and give the results that corroborate perfectly our analytical predictions.

关键词： dissipative bi-inductance network high-frequency mode continuous approximation dissipative complex Ginzburg–Landau equation programmable electronic generator LT-Pspice observations

The magnetic properties of diluted CoFe_2O_4 nanomaterials

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Chinese Physics B 2012年第4期21卷 513-518页

作者： R.Masrour M.Hamedoun A.Benyoussef Laboratory of Materials ProcessesEnvironment and QualityCady Ayyed UniversityNational School of Applied SciencesRoute Sidi Bouzid-BP 6346000 SafiMorocco LMPHE(URAC 12) Facultédes SciencesUniversitéMohamed V-AgdalRabatMorocco Institute for Nanomaterials and Nanotechnologies RabatMAScIRMorocco Academie HassanⅡdes sciences et Techniques RabatMorocco Academie HassanⅡdes sciences et Techniques RabatMorocco

The magnetic properties of （Cox Fe1-x）A （Zn1-x Fe1＋x）B O4 are studied using mean-field theory and the probability distribution law to obtain the saturation magnetization, the coercive field, the critical temperature, and the exchange interactions with different values of D （nm） and x. High-temperature series expansions （HTSEs） combined with the Pade approximant are used to calculate the critical temperature of （CoxFe1-x）A（Znl-xFe1＋x）BO4, and the critical exponent associated with magnetic susceptibility is obtained.

关键词： (CoxFe1-x)a(Zn1-xFe1+x)BO4 probability law saturation magnetization coercive field high-temperature series expansions