Publications

Recently the investigation of periodic motion of the delayed functional differential equations (DDEs) and the associated variation systems become the focus of many studies. One of the most important motivations is the milling process analysis. Different techniques are used to obtain approximate solutions for the delayed functional differential equations (DDE). All these models used the stability lobe diagrams in order to choose the maximum axial depth of cut, for a given spindle speed associated with the chatter free machining. In this work, a semi discretization method is briefly explained and has been applied for 1-DOF (degree of freedom) and 2-DOF milling system in order to build the stability lobe diagrams.

Bilayer of nickel and nickel oxide were deposited on glass substrates using RF magnetron sputtering technique. The magnetic properties of the prepared thin films were carried out at room temperature in both parallel and perpendicular magnetic field to the sample. The Preisach model was applied to provide a mathematical model of the magnetic hysteresis loop in the case of parallel geometry, along the easy axis of the bi-layer NiO / Ni. Good agreement was obtained between the theoretical and experimental results.

In this paper, an adaptive tracking controller for a piezo-actuated stage is designed considering the LUGRE model. The adaptation algorithm of the parameterized hysteretic function is used to achieve a displacement-tracking objective under the mechanical parameters uncertainties. The Lyapunov theory is used to derive an adaptive law for the system stability. The effectiveness of the proposed controller is validated considering real-time simulation. The validation results of the proposed controller presents good performances and robustness under an external load-disturbance and parameter uncertainties.

A robust nonlinear controller based on an improved feedback linearization technique with state observer is developed for a class of nonlinear systems with uncertainties and external disturbances. First, by combining classical feedback linearization approach with a discontinuous control and a fuzzy logic system, we design and study a robust controller for uncertain nonlinear systems. Second, we propose an optimized extended Kalman filter (EKF) for the observation of the states. The parameters to be optimized are the covariance matrices Q and R, which play an important role in the EKF performances. The particle swarm optimization algorithm insures this optimization. Lyapunov synthesis approach is used to prove the stability of the whole control loop. The proposed approach is applied on a two-link robot system under Matlab environment. Simulation results have confirmed the effectiveness of the proposed approach against uncertainties and external disturbances; and exhibited a more superior performance than the non-improved control actions.

Rock typing is a process of rock classification based on mineralogical composition, grainshape pore size distribution (PSD) and communication. In addition to rock-fluid interaction, dynamic behavior and the capillary effect are also considered. In that purpose data need process involve: integrating, analyzing and synthesizing data brought out from different source: Petrophysics, cores analysis, well tests, MDT tooland production profiles. Achievement of rock typing reservoir based on fluid - solid behavior and their relation constitute an important issue not only for making distinguished different rock types but also for fluid gas contacts.For the case study, our investigation is concerned with the determination of the rock type dynamism resulting in reservoir rocks having similar dynamic behavior. Outcome from this process is to establish a representative petrophysical model able to predict any effect own to the change of the rock properties or fluid characteristics. Establishment of numerical model in  that context, and its relative changes can be ascribed to rapid petrophysical variation characteristics: related to pore size, geometry, grain size distribution, fluid behavior and circulation with essential reference to permeability. This latter can affect the simulation time and consequently, the accuracy in the calculation process. In this conducted investigation, application of linear regression method is involving permeability and porosity core measurement, stressing on their coefficient of correlation. Results have led to different clusters classification according to the linearity regarding permeability-porosity changes. Extrapolation can be made for the non-cored reservoir sections or non-cored boreholes associated to the considered field. In that principle geological models can be set. Application of these listed method for TAGI (TriasArgilo-GreseuxInferieur: Lower Shaly – SansdtoneTriasic Formation) in B-H Basin (Algeria) has revealed the presence of six main rock types: sand type 1 (RT-1), sand Type 2 (RT-2), sand type 3 (RT-3), sand type 4 (RT-4), sand type 5 (RT-5) and sand type 6 (RT-6).

In this paper, a new metallic thin film engineering aspect is proposed to achieve superior absorption for TiO2/Metal/TiO2 on Silicon substrate UV-based photodetectors (PDs). The overall device optical performance comparison with three dissimilar metallic layers (Au, Ti, and Ag) is performed numerically using accurate solutions of Maxwell׳s equations. A comprehensive study of the device optical parameters such as the integral absorption, reflection, and rejection ratio is carried out, in order to reveal the device optical performance for UV optical interconnects and environment monitoring applications. We find that the optical performance are considerably improved as compared to the conventional design, where the proposed design offers superior integral absorption and lower total reflection with an acceptable rejection ratio in comparison with those provided by the conventional one. These improvements suggest the opportunity for optimizing the proposed design using particle swarm optimization (PSO) approach for achieving higher optical performance, where excellent capability is recorded in enhancing the device optical behavior. The obtained results make the prop sed device very efficient for compatible CMOS modern technology.

In this paper, a new hybrid approach by combining numerical investigation and Support Vector Machines (SVMs) classifier is proposed to study the thermoelectric performance of nanoscale Double Gate Junctionless DG JL MOSFET. In this context, a new Figure of Merit (FoM) parameter which combines both electrical and reliability characteristics is proposed. Moreover, the impact of Gaussian channel doping profile (GCD) in enhancing the DG JL MOSFET reliability against the self-heating effects (SHEs) is presented. The proposed design thermal stability and electrical characteristics are investigated and compared with those of the conventional structure in order to reveal the device performance including SHEs. It is found that the amended channel doping has a profound implication in improving both the device electrical performance and the reliability against the undesired self-heating and short channel effects (SCEs). Furthermore, the transistor thermal behavior analysis involves classification of the device performance by taking into account the device reliability. For this purpose, SVMs are adopted for supervised classification in order to identify the most favorable design configurations associated with suppressed SHEs and improved electrical performance. We find that the proposed design methodology has succeeded in selecting the better designs that offer superior reliability against the SHEs. The obtained results suggest the possibility for bridging the gap between high electrical performances with better immunity to the SHEs.

Security is an important issue in image storage and communication, encryption is one of the most common ways to ensure security. Recently, many schemes based on chaotic map have been proposed, but most of this method suffers from small key space, which makes them vulnerable to brute forces attacks. In this study, we design a highly robust novel symmetric image encryption scheme which offer good confusion and diffusion qualities, and a large key space to ensure popular security factor and to overcome the weaknesses of the state of the art encryption schemes. In the security analysis section, we prove that our scheme can resist most known attacks, such as cipher image only attack, known and chosen plain image attacks, differential and exhaustive attacks. It is shown in this paper that the use of polar decomposition with chaotic map can gives a fast and secures encryption.

Wireless capsule endoscopy (WCE) has several benefits over traditional endoscopy such as its portability and ease of usage, particularly for remote internet of things (IoT)-assisted healthcare services. During the WCE procedure, a significant amount of redundant video data is generated, the transmission of which to healthcare centers and gastroenterologists securely for analysis is challenging as well as wastage of several resources including energy, memory, computation, and bandwidth. In addition to this, it is inherently difficult and time consuming for gastroenterologists to analyze this huge volume of gastrointestinal video data for desired contents. To surmount these issues, we propose a secure video summarization framework for outdoor patients going through WCE procedure. In the proposed system, keyframes are extracted using a light-weighted video summarization scheme, making it more suitable for WCE. Next, a cryptosystem is presented for security of extracted keyframes based on 2D Zaslavsky chaotic map. Experimental results validate the performance of the proposed cryptosystem in terms of robustness and high-level security compared to other recent image encryption schemes during dissemination of important keyframes to healthcare centers and gastroenterologists for personalized WCE.

focuses on the Cenomano-Turonian sediments observed in Thénièt El Manchar, the Bellezma-Batna Mountains, their evolution and the recognition of the main dating markers. The analysis (qualitative and quantitative) of the planktonic and benthic foraminifera and that of the ostracodes makes it possible to reconstitute the evolution of the paleo-environment and to estimate the variations of the relative paleo-depths. During the lower middle Cenomanian (Units IA, IB, IC and the lower part of ID), the microfaunistic associations are dominated by agglutinated benthic foraminifera testifying to a cold environment corresponding to the circalittoral deposits, in association with whole shells of ostracods indicating a weak hydrodynamism. In these deposits, the associations show a low to medium specific diversity and a more or less high faunistic richness, indicating trophic conditions and oxygenation considered normal. As for Unit ID (upper Cenomanian), it contains benthic foraminiferal biocenoses characteristic of warm and agitated seas. The return to deeper conditions, in the final terms of the Cenomanian and the beginning of the Turonian (Unit IIA), during a transgressive phase, is justified by the classical success of the events selected in North Africa, namely: The abundance of planktonic foraminifera, filaments and the drastic reduction of ostracofauna. These different elements open a reflection on the recorded paleo-environmental perturbations, the gradual disappearance of environmental stress and the return to relative normal conditions. These paleo-environmental interpretations agree with the data of the regional palaeogeographic context and highlight Tethysian features. Key words: sedimentology, geochemistry, paleo-environment, Cenomanian, Turonian, Batna, Algeria.