A robust nonlinear controller based on an improved feedback linearization technique with state observer in presence of uncertainties and external disturbances is developed for a class of nonlinear systems. First, by combining classical feedback linearization approach with a robust control term and a fuzzy logic system, we design and study an efficient controller for such systems. Second, we propose an optimized extended Kalman filter for the observation of the states. The parameters to be optimized are the covariance matrices Q and G, which play an important role in the extended Kalman filter performances. This optimization is insured by the particle swarm optimization algorithm. The Lyapunov synthesis approach is used to prove the stability of the whole control loop. The proposed approach is simulated on a nonlinear inverted-pendulum system. Simulation results demonstrate the robustness and effectiveness of the proposed scheme and exhibit a more superior performance than its conventional counterpart.

The basin of Timgad belongs to the North-Eastern Algerian Saharan Atlas; it is located at the northern extension of the Aures Mountains. The basin is an asymmetrical syncline oriented East-West covering an area of 1000 Km2. The climate is semi-arid (cold winter and hot summer) with average annual rainfall not exceeding 400 mm. Recently, the increasing agricultural activities led to an excessive exploitation of groundwater resources. In order to meet this rising water supply demands, implementing a water resources management policy is a priority which should be based on a basin hydrogeological study. Effectively, the geological and geophysical studies have confirmed the presence of permeable Miocene and Cretaceous formations (sandstone and carbonate); relatively resistant affected by fractures network, which are probably forming a confined aquifers. Indeed, recent wells drilled in the basin center and their boundaries; show that the aquifers are artesian. The sandstone aquifer of the Miocene is the most important, it is characterized by significant thickness which can exceed 200m, its extension as well as its particular corrugated geometry, characterized by a wavy shape, which forming a series of shale-marl filling depressions, influences the groundwater flow, actually, the piezometric surface illustrates groundwater convergent flow oriented to the east, towards Bou el freis, likewise the sandstone aquifer is marked by the presence of a West-East drainage axis which separates the basin northern part characterized by a low reservoirs hydraulic capacity from the southern part distinguished by the groundwater relative abundance. Groundwater is generally easily extracted, except the northern part of the basin where the top shale-marl layer is thickens to over 1000m.

The purpose of this study was to establish a method based on an iterative scheme to approximate the numerical solution obtained from finite elements analysis for an RVE in two and three dimensions based on the homogenization concept for the assessment of the effective properties. The bounds of Hashin–Shtrikman and Voigt–Reuss were considered in the iterative process based on an updating of the constitutive relations of these models respectively. In this study, by assumption, we took the particular case of the heterogeneous materials with several elastic isotopic phases. The output variables considered using the iterative process are the bulk, shear modulus and the thermal conductivity. We have found a fast convergence of the iterative solution to the numerical result with a suitable concordance between the two solutions at the final step.

Encryption is the way to ensure confidentiality of different data, digital images have special features as large data, bulky data, and strong correlation between pixels, which makes traditional encryption algorithms not suitable for image encryption. For this concern, we propose a novel lossless encryption scheme for digital images based on combination of matrix transformations and XOR operation. The numerical experimental results confirms that the proposed method achieves high security level against brute force attacks, statistical attacks and sensitivity analysis, moreover the suggested algorithm provides a good randomness properties, thus our method can be applied for image encryption and transmission in sensitive domains.