A. Fahmi and A. Qachaou

This work is a contribution to the study of the elementary excitations and magnetic properties of a super-lattice such as [Co(t_m)/Cu(t_nm)] N , represented by the N atomic planes Heisenberg ferromagnetic system where the nearest neighbour and next nearest neighbour exchange, and dipolar interactions are considered in addition to the surface anisotropy. This study is based on the linear spin waves theory. In the presence of the exchange alone, the excitation spectrum E(k) and the magnetization < S^z > analytical expressions are obtained for N=3, 5 and 10 atomic planes using the Green's function formalism. We also highlighted the existence of N excitation modes in conformity with former studies. A numerical study of the surface anisotropy and dipolar interaction contributions is also reported. A good agreement between the calculated and measured magnetization evolution with an applied magnetic field at 300K is obtained.

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Key words :  super-lattice, spin waves theory, anisotropy, excitation spectra, magnetization, dipolar interaction.

Laboratoire de Physique de la matière condensée, Faculté des sciences, KENITRA

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A.HABBOU, M. FADILI, B.HARTITI

 This study deals with n⁺p type crystalline silicon solar cells performances using the Taguchi method in its optimum. We; then, discuss different physical parameters influence on photovoltaic material propreties.

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Key words : solar cells, silicon, junction n⁺p, conversion efficiency, Taguchi methodology, numeric simulation (PC1D)

Laboratory of Material Physics and Applications of the Renewable Energies FST of Mohammedia BP 146, 20630 Mohammedia, Morocco,
E-mail: habbou@uh2m.ac.ma

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K.Fourrate and M.Loulidi

In this paper, we extend the Nagel-Schreckenberg (NaSch) model by introducing disordered acceleration and deceleration terms. The disorder leads to segregated states where the flow is constant at intermediate densities for high values of breaking probability p. Within the model we present a density wave behavior appears below a critical value of p. Such result was found in car following models with an optimal velocity. The behavior of the gap distribution shows that the traffic exhibits a self organized criticality for high values of p and random deceleration.

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PACS numbers : 05.60.+w, 45.70.Vn, 02.50.Ey

LMPHE , Département de physique B.P.1014, Faculté des sciences, Agdal, Rabat, Morocco.

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  Hamid Ez-Zahraouy*, Zoubir Benrihane, Abdelilah Benyoussef

The effect of the absorbing sites with an absorbing rate β₀ , in both one absorbing site (one way out) and two absorbing sites (two ways out) in a road, on the traffic flow phase transition is investigated using numerical simulations in the one-dimensional cellular automaton traffic flow model with open boundaries using parallel dynamics. It is found that the behavior of density and current depends strongly on the value of β₀ , the position of the way(s) out from the entering and the distance between the ways out. Indeed, in the case of one way out, there exist a critical position of the way out i_c1 below which the current is constant for β₀ <β_0c2 and decreases when increasing β₀ for β₀ >β₀c2 When the way out is located at a position greater than i _c2 , the current increases with β₀ for β₀ <β_0c1 and becomes constant for any value of β₀ greater than β_0c1. While, when the way out is located at any position between i_c1 and i_c2 (i_c1<i_c2), the current increases, for β₀< β_0c1 , with β₀ and becomes constant for β_0c1 < β₀ <β_0c2 and decreases with β₀ for β₀ > β_0c2 . In the later case the density undergoes two successive first order transitions; from high density to maximal current phase at β₀ =β_0c1 and from intermediate density to the low one at β₀ =β_0c2 . In the case of two ways out located respectively at the positions i₁ and i₂, the two successive transitions occur only when the distance i₂ - i₁ seating the two ways is smaller than a critical distance d_c , otherwise the traffic flow increases with β₀, passes through a maximum at β₀ =β_max and decreases for any value of β₀ greater than β_max. The values of β₀c1, β₀c2, i_c1, i_c2 and d_c depend on the injecting rate α, the extracting rate β and the position(s) of the way(s) out in the road. Moreover i_c1 and i_c2 , depend on the size of the system. Phase diagrams in the (α, β₀ ), ( β, β₀ ) and (i₁ ,β₀ ) planes are established. It is found that the transitions between Free traffic, Congested traffic and maximal current phase are first order.

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Pacs number : 05.50.+q , 64.60.Cn , 75.30.Kz , 82.20.wt
Keywords :Traffic flow, Open boundaries, Numerical simulation, absorbing site,
                    Phase diagrams.

Laboratoire de Magnétisme et de la Physique des Hautes Energies Université Mohammed V, Faculté des Sciences, Avenue Ibn Battouta,
B.P. 1014, Rabat, Morocco

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E.M.Barj^a*, M.Afifi^a, A.Idrissi^a, S.Rachafi^b, K.Nassim^b

A wavelet algorithm developed to improve metrology based on electronic speckle pattern intérferometry (ESPI) is presented. The wavelet algorithm is based on the calculation of the continuous wavelet transform of a modulated speckle correlation fringes .The Paul wavelet is used , the extraction of the maximum scales of the modulus of the wavelet transform leads simply to the phase gradient distribution. The advantage of the method is to provide phase distribution, with a high accuracy, from a single interferogram without unwrapping step.

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PACS numbers :  42.62. Eh ; 42.30.Ms ; 42.30.Rx

a Université Hassan II-Mohammedia, faculté des sciences,Ben M’sik, Casablanca-Morrocco
b Université Chouaib Doukkali, faculté des sciences , El Jadida-Morrocco

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M. Rjeb ^a,b , A. Labzour ^b , A. Rjeb ^b* , S. Sayouri ^c , M. Chafik El Idrissi ^d ,
S. Massey ^e , A. Adnot ^e D. Roy ^e

In the present work we are concerned in the study, by means of the X-ray Photoelectron Spectroscopy (XPS), of the solar radiation impact (atmospheric environment), on the natural aging of the polypropylene (PP). The study has focused on two periods of aging, 60 and 80 days. Results of the quantitative analysis show an important degradation of the aged material due essentially to the contamination by oxygen, The latter being the main contaminating agent in surface. The solar radiation accelerates the oxidation of the surface of the PP by rupture of the C-H bonds. The decomposition of C1s and O1s peaks has allowed a best comprehension of the chemical reactional mechanisms, in terms of carbon-oxygen bonds (C=O, C-OH and O=C-O) responsible of the photo-oxidation.

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Key words : Polymers ; Polypropylene ; Ageing ; Photo-oxidation ; XPS.

a LIRM, Faculté des sciences et technique Fès, BP 2202 Fès , Morrocco
b LPS, Faculté des sciences Dhar El Mahraz, BP 1796 Fès Atlas, Morrocco
* Auteur correspondant : E-mail : arjeb@yahoo.com
c LPTA, Faculté des sciences Dhar El Mahraz, BP 1796 Fès Atlas, Morrocco
d LPSI, Département de physique, Faculté des sciences, BP 133, Kenitra, Morrocco
e LPAM, CERPIC, Pavillon Vachon, Université Laval, Québec, Canada, G1K 7P4

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A.HADER, K.ZOUHIR and Y.BOUGHALEB *

In the limit where the ratio of the surfaces diffusion coefficient to the deposition rate D/F ∞ → , the surface consists of wedding-cake structures. In order to understand the growth dynamics and the scaling properties of theses interfaces, we have calculated the time evolution of its width ω(L,t) for both one and two dimensional lattice. By the use of the dynamic scaling approach, we find that ω(L,t) scales with time t and length L as ω(L,t)≈L^α f(t/L^α/β ) where f is a scaling function and α and β are respectively the roughening and the growth exponents. The values of theses exponents are in good agreement with the theoritical ones predicted by the Edwards-Wilkinson equation.

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PACS numbers :  05,50.+q-05.60.cd-68.35.Fx

Laboratoire de Physique de la Matière Condensée. Université Hassan II-Mohammedia Faculté des sciences Ben M'sik BP.7955 Casablanca Morrocco

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Boumhali ² , D. Saifaoui ¹ , A. Dezairi ² , B. Zine ¹

In this work we studied the collisions in the sheath and their influence on the energy transferred to the cathode by Monte carlo simulation .The comparison between results obtained by Monte Carlo simulation and those obtained by simulation of Runge Kutta is carried out. We stadied too the influence of the collision on the erosion of the cathode, and we give a technique to calculate the energy of vaporisation.

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Keywords:  Spin waves, super-lattices, Green’s functions, dispersions curves, magnetization.

(1)Faculté des Sciences Ain Chock BP 53 66 Maarif Casablanca Morrocco
(2)Faculté des Sciences Ben M’Sik Casablanca Morrocco

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S. Makham¹ , M. Zazoui¹ and J. C. Bourgoin²

 This paper describes the principle of the study which is based on electroluminescence to extract the parameters characterizing the recombination centers induced by irradiation in a solar cell. This technique is able to provide direct information on each individual junction constituting the multijonctions. The results are compared with those obtained by electrical methods.

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1 Laboratoire de Physique de la Matière Condensée, B. P. 146, F.S.T.M. Mohammedia, Morrocco.
2 Laboratoire des Milieux Désordonnés et Hétérogènes, Université Pierre et Marie Curie
    ( Paris VI), U.M.R. 7603, Tour 22, 4 place Jussieu 75252, Paris cedex-05.

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EL-Lssas El ayachi; A. Ouazzani T.H. M. Ouazzani-Jamil and S. Dekkaki

In this paper we discuss some algebraic and the structure of the phase space of an integrable quartic potential. It is a special case of the so-called Garnier system:

H = 1/2 ( P₂¹ + P₂²) + (q₂² + q₁² )² + aq₁² + bq₂²  

In order to carry out the analytical invertigation we get first the separability of the variables (separation of the Hamilton -Jacobi equation); afterwards we give a complete description of the real phase space topology.

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Laboratoire de physique du solide Faculté des sciences Dhar El Mahraz B.P 1796 Fès-atlas Morocco
e-mail : ellssas@caramail.com
e-mail : ouazzanijamil@hotmail.com

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Mohamed. BOUR ¹ ; Mohamed. LHARCH ¹ ; Abdelkarim. ZATNI ¹ ; Philippe. GELIN ³ ;
Michel. CAUTERMAN ⁴ ; Driss. KHATIB ²

The finite elements method has made proof efficiency and precision in many areas as mechanics, thermal, components physics and more recently in the electromagnetism. Its applications allow the processing of homogeneous, inhomogeneous, isotropic or anisotropic medias for any geometry. Our study, concerns the analysis of a coaxial guide in the presence of a saturated ferrite material, the goal of this study is to deduce the electromagnetic behaviour inside the coaxial guide, by determining physical parameters variations in function of material characteristics. The electromagnetic study; lead us to use a coupled equation system of Helmholtz type, which is difficult to solve analytically. This is why we have developed a method of space discretization called FINITE-ELEMENT METHOD, to solve numerically the problem.

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1 Laboratoire de la Physique de la Matière Condensée ; Université Ibn Zohr, ESTA, BP 33/S Agadir, Morocco.
2 Laboratoire de la Physique Théorique de Solide ; Université Ibn Zohr, Faculté des Sciences, Agadir, Morocco.
3 Laboratoire d’électronique et système de communication à l’ENSTBr,UBO, Brest, France.
4 D.R.E –Supélec, Service d’électromagnétisme, Gif sur Yvette, Cedex,91192, France.

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H. Ez-Zahraouy, K. Jetto, A. Benyoussef

The effect of mixture lengths of vehicles on the asymmetric exclusion model is studied using numerical simulations for both open and periodic boundaries in parallel dynamics. The vehicles are filed from their length, the small cars Type 1 occupy one cell whereas the big ones Type 2 takes two. In the case of open boundaries two varieties of models are presented. The former model corresponds to a chain with two entries where densities are calculated as a function of the injecting rates α₁ and α₂ of vehicles type 1 and type 2 respectively, and the phase diagram (α₁ , α₂ ) is presented for a fixed value of the extracting rate β. In this case the first order transition from low to high density phases occurs at α₁ +α₂ =β and disappears for α₂ >β. The latter model correspond to a chain with one entry, where α is the injecting rate of vehicles independently of their nature. Type1 and type2 are injected with α₁ and α₂ respectively, where α₂ =nα, n is the concentration of type2 and α₂ ≤α₁ ≤α. Densities are calculated as a function of the injecting rates α, and the phase diagrams (α,β) are established for different values of n. In this case the gap which is a characteristic of the first order transition vanishes with increasing α for n ≠ 0.However, the first order transition between high and low densities exhibit an end point above which the global density undergoes a continuous passage. The end point coordinate depends strongly on the value of n. In the periodic boundaries case, the presence of vehicles type2 in the chain leads to a modification in the fundamental phase diagram (current, density). Indeed, the maximal current value decreases with increasing the concentration of vehicles type 2, and occurs at higher values of the global density in contrast with what was found by Schadschneider et al. [20].

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PACS numbers :  05.50.+q , 64.60.Cn , 75.30.Kz , 82.20.wt

Laboratoire de Magnétisme et de la Physique des Hautes Energies Université Mohammed V, Faculté des Sciences, Avenue Ibn Batouta,
B.P. 1014 Rabat, Morocco.

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M. El Mouden ¹, D. Saifaoui ¹, A. Dezairi ², A.Rouak ¹, H. Imzi ¹

In this paper we have studied the influence of reversed shear on the improvement of the confinement’s quality in the plasma of tokamak and especially in reducing the anomalous transport. For that, we have used a special model for the drift wave fields. Comparison between particles trajectories for normal and reversed shear is carried out in 2D and 3D presentation. Also, the diffusion coefficient of particles for the two cases, normal and negative shear, is evaluated.

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Key words :  Plasma confinement, Tokamak, Anomalous transport, Magnetic shear, Transport barrier, Particles diffusion, Radial electric field

1 Laboratory of Theoretical Physics, Faculty of Sciences- Ain Chock, Casablanca, Morocco,
2 Laboratory of the Physics of Condensed Matter, Faculty of Sciences- Ben M’sik, Casablanca, Morocco