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Sid Ahmed Houari M.,University Djilali Liabes | Tounsi A.,University Djilali Liabes | Anwar Beg O.,Gort Engovation Propulsion
International Journal of Mechanical Sciences | Year: 2013

A new higher order shear and normal deformation theory is developed to simulate the thermoelastic bending of functionally graded material (FGM) sandwich plates. By dividing the transverse displacement into bending, shear and thickness stretching parts, the number of unknowns and governing equations for the present theory is reduced, significantly facilitating engineering analysis. Indeed, the number of unknown functions involved in the present theory is only five, as opposed to six or even greater numbers in the case of other shear and normal deformation theories. The present theory accounts for both shear deformation and thickness stretching effects by a sinusoidal variation of all displacements across the thickness, and satisfies the stress-free boundary conditions on the upper and lower surfaces of the plate without requiring any shear correction factor. The sandwich plate faces are assumed to have isotropic, two-constituent material distribution through the thickness, and the material properties are assumed to vary according to a power law distribution in terms of the volume fractions of the constituents. The core layer is still homogeneous and composed of an isotropic ceramic material. The influences of thickness stretching, shear deformation, thermal load, plate aspect ratio, side-to-thickness ratio, and volume fraction distribution on plate bending characteristics are studied in detail. Numerical examples are presented to verify the accuracy of the present theory. The present study is relevant to aerospace, chemical process and nuclear engineering structures which may be subjected to intense thermal loads. © 2013 Elsevier Ltd.

Bachir R.G.,University of Mascara | Benali M.,University Djilali Liabes
Asian Pacific Journal of Tropical Biomedicine | Year: 2012

Objective: To examine the in vitro antimicrobial activities of essential oil of the leaves of Eucalyptus globulus (E. globulus). Methods: The essential oils of this plant were obtained by the hydrodistillation method. The inhibitory effects of this essential oil were tested against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) by using agar disc diffusion and dilution broth methods. Results: The results obtained showed that essential oil of the leaves of E. globulus has antimicrobial activity against gram negative bacteria (E. coli) as well as gram positive bacteria (S. aureus). Conclusions: The encouraging results indicate the essential oil of E. globulus leaves might be exploited as natural antibiotic for the treatment of several infectious diseases caused by these two germs, and could be useful in understanding the relations between traditional cures and current medicines. © 2012 Asian Pacific Tropical Biomedical Magazine.

Henderson J.,Baylor University | Ouahab A.,University Djilali Liabes
Computers and Mathematics with Applications | Year: 2010

In this paper, we first present an impulsive version of the Filippov-Ważewski theorem and a continuous version of the Filippov theorem for fractional differential inclusions of the form (D* α y (t) ∈ F (t, y (t)),, a.e. t ∈ J {set minus} {t1, ..., tm}, α ∈ (1, 2],; y (tk +) = Ik (y (tk -)),, k = 1, ..., m,; y′ (tk +) = over(I, -)k (y (tk -)),, k = 1, ..., m,; y (0) = a, y′ (0) = c,) where J = [0, b], D* α denotes the Caputo fractional derivative, and F is a set-valued map. The functions Ik, over(I, -)k characterize the jump of the solutions at impulse points tk (k = 1, ..., m). Additional existence results are obtained under both convexity and nonconvexity conditions on the multivalued right-hand side. The proofs rely on the nonlinear alternative of Leray-Schauder type, a Bressan-Colombo selection theorem, and Covitz and Nadler's fixed point theorem for multivalued contractions. The compactness of the solution set is also investigated. Finally, some geometric properties of solution sets, Rδ sets, acyclicity and contractibility, corresponding to Aronszajn-Browder-Gupta type results, are obtained. We also consider the impulsive fractional differential equations (D* α y (t) = f (t, y (t)),, a.e. t ∈ J {set minus} {t1, ..., tm}, α ∈ (1, 2],; y (tk +) = Ik (y (tk -)),, k = 1, ..., m,; y′ (tk +) = over(I, ̄)k (y (tk -)),, k = 1, ..., m,; y (0) = a, y′ (0) = c,) and (D* α y (t) = f (t, y (t)),, a.e. t ∈ J {set minus} {t1, ..., tm}, α ∈ (0, 1],; y (tk +) = Ik (y (tk -)),, k = 1, ..., m,; y (0) = a,) where f : J × R → R is a single map. Finally, we extend the existence result for impulsive fractional differential inclusions with periodic conditions, (D* α y (t) ∈ φ (t, y (t)),, a.e. t ∈ J {set minus} {t1, ..., tm}, α ∈ (1, 2],; y (tk +) = Ik (y (tk -)),, k = 1, ..., m,; y′ (tk +) = over(I, -)k (y (tk -)),, k = 1, ..., m,; y (0) = y (b), y′ (0) = y′ (b),) where φ : J × R → P (R) is a multivalued map. The study of the above problems use an approach based on the topological degree combined with a Poincaré operator. © 2009 Elsevier Ltd. All rights reserved.

Mechab I.,University of Mascara | Mechab B.,University Djilali Liabes | Benaissa S.,University Djilali Liabes
Composites Part B: Engineering | Year: 2013

This study presents the analytical solutions of static and dynamic analysis of functionally graded plates using Four-variable refined plate theory. The objective of this paper is to develop a model to employ the new function ψ(z) for analysis the static and dynamic of functionally graded plates. The validity of the theory is shown by comparing the present results with those of the classical, the first-order, and the other higher-order theories. The results are in good agreement with solution of Reddy. © 2012 Elsevier Ltd. All rights reserved.

Based on first-principles calculation the change of magnetic configurations and electronic structure of perovskite oxide BaFeO3 is investigated by introducing a new potential energy function which has been determined via the density functional theory basis with U-Hubbard Hamiltonian (DFT+U). The exchange and correlation potential is employed using GGA+U approach by combining available experimental measurements and the data from the current theoretical calculations. The implementation of the U-Hubbard term in this calculation allows more comprehension on the BaFeO3 behavior and has ameliorated the obtained results. The spin effect is given for the considerable oxide by investing the cubic phase. Possible different magnetic configurations (ferromagnetic FM and anti-ferromagnetic AFM) for the BaFeO3 oxide. The implementation of the new approach GGA+U shows the Coulomb interaction inside the d-states exactly which can play an important role in the orbital systems of both elements the ferrite (Fe) and barium (Ba). By the band structure and the densities of states analysis. BaFeO3 is a strong candidate for spintronic applications. © 2014 Elsevier Ltd. All rights reserved.

Ouahab A.,University Djilali Liabes
Computers and Mathematics with Applications | Year: 2012

In this paper, we first present a version of Filippov's Theorem for fractional semilinear differential inclusions of the form, ( c Dαy-Ay)(t)∈F(t,y(t)), a.e. t∈[0,b],y(0)= y0∈X, where cDα is the Caputo fractional derivative and F is a set-valued map. After several existence results, the compactness of solutions sets is also investigated. Some results from topological fixed point theory together with notions of measure of noncompactness are used. © 2011 Elsevier Ltd. All rights reserved.

Younes M.,University Djilali Liabes | Khodja F.,University Djilali Liabes | Kherfane R.L.,University Djilali Liabes
Energy | Year: 2014

This paper presents a new and efficient method for solving EPD (economic power dispatch) problem. To solve this problem we have combined two meta-heuristic methods, the FFA and the mGA. The acceleration of the convergence speed, the improved solution quality and the balance between exploration and exploitation are achieved with FFA-mGA approach. The searching process starts with the FFA by initializing a group of random fireflies. After that, the search is pursued by the mGA. Then, the best results (better than FFA) found from mGA are still communicated to the FFA as an initial space search.The process is repeated than until the final solution is reached. The strength of the proposed approach is tested and validated on the standard IEEE 30-bus system by solving several cases as: the fuel cost minimization, Emission minimization, Emission and cost minimization simultaneously, fuel cost minimization with Sine Components, Piece-wise quadratic cost functions minimization and finally, the effect of the integration of wind energy in the system. The obtained results are compared with the classic FFA and the GA (genetic algorithm) and those in literature. The results show that the proposed approach provides accurate solutions for any type of the objective functions. © 2013 Elsevier Ltd.

Particularly interesting as candidates to technological applications are the manganese perovskites with AMnO3 formula. Their magnetic structure was described as resulting from a particular ordering of the occupied d orbitals which possess. This reflects my understanding of the structural, electronic and magnetic phenomena, which is well established only in the limit where the systems show localized or itinerant electron behavior. In general, the perovskites of ABO3-type are well known with their (anti)ferroelectric, piezoelectric and (anti)ferromagnetism properties applied in considerable technological investigations. In my paper, I studied the ground states properties of the BaMnO3 perovskite oxide. My structural properties are given using LSDA, GGA, LSDAU and GGAU in the aim to introduce the exchange correlation potential. In the following paper, I use the GGAU on the electronic and magnetic properties calculation. I show in my study the density of states, the band structures and also the charge density figures. My results such as lattice parameter, bulk modulus and its pressure derivative agree very well with available theoretical works and experimental data. I discuss the magnetic moment and the U-Hubbard effect introduced by LSDAU and GGAU on my results given in this paper. © 2011 Elsevier B.V.All rights reserved.

Faraoun K.M.,University Djilali Liabes
Expert Systems with Applications | Year: 2014

We propose an evolutionary computation approach to design a fast and secure block cipher using non-uniform second-order cellular automata. We build a flexible block ciphering model that permit the construction of a huge space of possible instances defined each one by a finite set of elementary transition rules. The constructed space is explored using a genetic algorithms strategy in order to find an optimal solution with respect to the strict avalanche criterion used as fitness measurements. The genetically designed cipher is benchmarked experimentally using conventional statistical tests, and shown to have very admissible characteristics leading to a very acceptable level of cryptographic security. Moreover, performances analysis shows that the designed cipher permit to achieve a high encryption/decryption speed, and compete many of the existing standardized ciphers. © 2014 Elsevier Ltd. All rights reserved.

Faraoun K.M.,University Djilali Liabes
Optics and Laser Technology | Year: 2014

We propose a new tweakable construction of block-enciphers using second-order reversible cellular automata, and we apply it to encipher RGB-colored images. The proposed construction permits a parallel encryption of the image content by extending the standard definition of a block cipher to take into account a supplementary parameter used as a tweak (nonce) to control the behavior of the cipher from one region of the image to the other, and hence avoid the necessity to use slow sequential encryption's operating modes. The proposed construction defines a flexible pseudorandom permutation that can be used with efficacy to solve the electronic code book problem without the need to a specific sequential mode. Obtained results from various experiments show that the proposed schema achieves high security and execution performances, and enables an interesting mode of selective area decryption due to the parallel character of the approach. © 2014 Elsevier Ltd.

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