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Lakouari, N.; Ez-Zahraouy, H.; Benyoussef, A., E-mail: ezahamid@fsr.ac.ma
AbstractAbstract
[en] In this paper, we propose a stochastic Cellular Automata (CA) model to study traffic flow at a single-lane urban roundabout (resp. traffic circle) of N entry points (resp. exit points), the entry points are controlled by rates α_1 and α_2 while the removal rates from the exit points are denoted by β. The traffic is controlled by a self-organized scheme. Based on computer simulation, density profiles, global density and current are calculated in terms of rates. Furthermore, the phase diagrams for roundabout as well as traffic circle are constructed. It has turned out that the phase diagrams consist essentially of two phases namely free flow and jamming. It is noted that the typology of the phase diagrams of the roundabout is not similar to it in the traffic circle. Furthermore, we have compared the performance of the two systems in terms of the geometrical properties and the number of entry points. - Highlights: • Simulations are conducted to study traffic flow at a single-lane urban roundabout as well as traffic circle. • Phase diagrams for roundabout as well as traffic circle are constructed. • The performance of the two systems are compared in terms of the geometrical properties and the number of entry points
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S0375-9601(14)00882-2; Available from http://dx.doi.org/10.1016/j.physleta.2014.09.001; Copyright (c) 2014 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
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Bahmad, L.; Benyoussef, A.; Ez-Zahraouy, H., E-mail: ezahamid@fsr.ac.ma
AbstractAbstract
[en] The effect of a variable surface transverse magnetic field Ωs, on the order-disorder layering transitions of an Ising spin-((1)/(2)) model is investigated using mean field theory (MF) and finite cluster approximation (FC). For a film with finite thickness formed with N layers, each layer z transits at a fixed temperature from the ordered to the disordered phase, under the effect of the transverse magnetic field Ω(z)=Ωs/zα, (z=1, triple dot, N). These order-disorder layering transitions are absent for α=0 even if increasing the temperature and/or the surface transverse magnetic field. On the other hand, the dependency of longitudinal and transverse magnetisations on temperature and surface transverse magnetic field are illustrated for a fixed value of the exponent α
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S0304885301008071; Copyright (c) 2002 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
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AbstractAbstract
[en] The magnetic order-disorder layering transitions of a spin-1 Ising model are investigated, under the effect of a variable surface crystal field Δs, using the mean-field theory. Each layer k, of the film formed with N layers, disorders at a finite surface crystal field distributed according to the law Δk=Δs/kα, k=1,2,...,N and α being a positive constant. We have established the temperature-crystal field phase diagrams and found a constant tricritical point and a reentrant phenomenon for the first k0 layers. This reentrant phenomenon is absent for the remaining N-k0 layers, but the cricritical points subsist and depend not only on the film thickness but also on the exponent α. On the other hand, the thermal behaviour of the surface magnetisation for a fixed value of the surface crystal field Δs and selected values of the parameter α are established
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S0304885302004869; Copyright (c) 2002 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
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Mahjoubi, F.; Hamedoun, M.; Bakkali, F.Z.; Hourmatallah, A.; Benyoussef, A, E-mail: hamedoun@fesnet.net.ma
AbstractAbstract
[en] The cationic substitutions effects at different concentrations, within the ZnxCd1-xCr2Se4 lattice (0.35≤x≤0.58), on the electronic transfer in chromium's ion are investigated. For this purpose, after taking into account the exchange integrals, we use the Anderson-Kanamori theory of superexchange to determine the transfer integrals bσσ and bπσ. Using the conventional molecular orbital model, the covalency-mixing parameters λσ and λπ, the electron spin transfer coefficients fi(i=σ, π, s) and the total charge C are evaluated. The bσσ and bσπ variation with x, agrees with the passage of the system from ferromagnetic to antiferromagnetic order. For the compound presenting re-entrant behaviour (0.45≤x≤0.58), fs exhibits anomalies. The C increasing with x is consistent with the expected decrease in covalency of the non-magnetic cation in a tetrahedral site
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S0304885300004789; Copyright (c) 2000 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
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Benyoussef, A.; El Kenz, A.
International Centre for Theoretical Physics, Trieste (Italy)
International Centre for Theoretical Physics, Trieste (Italy)
AbstractAbstract
[en] New types of renormalization group theory using the generalized Callen identities are exploited in the study of the Ising model. Another type of two-step renormalization is proposed. Critical couplings and critical exponents yT and yH are calculated by these methods for square and simple cubic lattices, using different size clusters. (author). 17 refs, 2 tabs
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Sep 1989; 13 p
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Benyoussef, A.; El Kenz, A.
International Centre for Theoretical Physics, Trieste (Italy)
International Centre for Theoretical Physics, Trieste (Italy)
AbstractAbstract
[en] The influence of frustration on the phase transitions of a semi-infinite three-dimensional Ising model is investigated. Temperature-concentration phase diagrams for fixed values of the ratio of surface and bulk interactions can exhibit five different types of phase transition. (author). 6 refs, 1 fig
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Sep 1990; 5 p
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Benyoussef, A.; Saber, M.
International Centre for Theoretical Physics, Trieste (Italy)
International Centre for Theoretical Physics, Trieste (Italy)
AbstractAbstract
[en] Using the finite cluster approximation, phase diagrams of bond and site diluted three-dimensional simple cubic Ising models with a random field have been determined. The resulting phase diagrams have the same general features for both bond and site dilution. (author). 7 refs, 4 figs
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Sep 1987; 15 p
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Benyoussef, A.; Ez Zahraouy, H.
International Centre for Theoretical Physics, Trieste (Italy)
International Centre for Theoretical Physics, Trieste (Italy)
AbstractAbstract
[en] The three dimensional spin-1 Ising model with crystal field interactions exhibit tri-critical behaviour. Using an expansion technique for cluster identities of spin-1 localized spin systems, we study the influence of transverse magnetic field on this behaviour. Temperature-crystal-field phase diagrams is investigated for different values of transverse field. The longitudinal and transverse magnetizations, the quadrupolar moments are calculated. General formulae, applicable to structures with arbitrary coordination number N, are given. (author). 19 refs, 5 figs
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Sep 1993; 20 p
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Report
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Numerical Data
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Benyoussef, A.; Ez Zahraouy, H.
International Centre for Theoretical Physics, Trieste (Italy)
International Centre for Theoretical Physics, Trieste (Italy)
AbstractAbstract
[en] We study the phase diagram and magnetic properties of a transverse spin-1 Ising model with random longitudinal crystal field interactions within an expansion technique for cluster identities of spin-1 localized spin systems. The partially ordered phases appear for a particular two valued distribution P(Di) = 1/2[δ(Di-(1+α)D)+δ(Di-(1-α)D)], and for sufficiently small transverse field Ω. The longitudinal and transverse magnetizations, the quadrupolar moments are calculated. General formulae applicable to structures with arbitrary coordination number, are given. (author). 19 refs, 3 figs
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Sep 1993; 19 p
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AbstractAbstract
[en] The magnetic properties of ferrimagnetic mixed-spin Ising model in the checkerboard lattice are studied using Monte Carlo simulations. The variation of total magnetization and magnetic susceptibility with the crystal field has been established. A transition from an order to a disordered phase has been obtained in some critical value of the physical variables. The reduced transition temperature is obtained for different exchange interactions. The magnetic hysteresis cycles have been established. The multiples hysteresis cycle in checkerboard lattice are obtained. The multiples hysteresis cycle have been established. The ferrimagnetic mixed-spin Ising model in checkerboard lattice is very interesting from the experimental point of view. The mixed spins system have many technological applications such as in domain opto-electronics, memory, nanomedicine and nano-biological systems. The obtained results show that that crystal field induce long-range spin–spin correlations even bellow the reduced transition temperature
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Journal Article
Journal
Indian Journal of Physics (Online); ISSN 0974-9845;
; v. 91(12); p. 1553-1560

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