http://depot.umc.edu.dz/handle/123456789/1 Sat, 17 Oct 2026 19:10:08 GMT 2026-10-17T19:10:08Z http://depot.umc.edu.dz/handle/123456789/14860 Using mind mapping to develop students’ writing skill Abid Charef, Mouldia; Youcef, Beghoul Brain-friendly teaching aims to find out means to address the human mind and the brain via the known ‘language’. Using images, associations, radiant thinking, and other cognitive funds prove to trigger flawlessly the mental activity and enhance productivity at all levels. Mind Mapping happens to be one of these cognitive means. This study aims at investigating the extent to which Mind Mapping helps to lessen the cognitive demands of the writing task. Besides the cognitive endeavour, it attempts to enhance students’ engagement in the writing process. Hence, it is hypothesized that if second year students at the ENSC used Mind Mapping appropriately as a prewriting strategy, they would write better essays. The theoretical background consists of mind/brain related issues, Mind Mapping’ design and values, and academic writing. The research tools are, basically, Classroom Action Research. In addition to a Students’ Questionnaire and a Teachers’ Survey, there are a Quasi-experiment, where Independent-Samples T-Test and PairedSamples T-Test were used to accounts quantitatively for the findings, the B2- level Cambridge Assessing Writing Performance Checklist (2016), for a qualitative assessment of the writing pieces, and a Padlet to scaffold classroom work. The findings bolstered the positive cognitive and psychological effects of the prewriting technique and the role it played in decreasing the demands of the writing task. More importantly, the treatment upshot a statistical significance of the results obtained buttressed by a qualitative improvement in the Experimental Group’s final drafts. Consequently, the research stressed Brain-based Teaching where autonomy, learning styles and strategies, collaborative learning…etc. were highlighted and, unconditionally, supported with an equal emphasis given to the necessity of training, use, and expansion of the use of this technique to a large scale in the teaching context. Wed, 26 Nov 2025 00:00:00 GMT http://depot.umc.edu.dz/handle/123456789/14860 2025-11-26T00:00:00Z http://depot.umc.edu.dz/handle/123456789/14859 La modélisation de nouvelles structures dans le domaine du guidage et du filtrage des ondes acoustiques. Amrani, Hamza; Grine, Farouk Acoustic metamaterials represent an exciting frontier in the control of waves and vibrations. The precise control of acoustic waves is fundamental for key technological applications, ranging from sound insulation to ultrasonic detection. In this work, the design, modeling, and analysis of novel two-dimensional phononic crystal (PnC) structures that integrate the architecture of auxetic materials are addressed. The objective is double: to create new structures capable of generating and controlling wide and tunable phononic bandgaps (PBGs), and to control the direction of energy flow and the propagation of acoustic waves. The study relies on the Finite Element Method (FEM) and the rigorous application of the Floquet-Bloch theory for the calculation of dispersion relations. We introduce and analyze two specific auxetic architectures derived from star-shaped honeycomb structure: the concave circular-headed structure and the Arabesque structure. A parametric study is performed on the geometric variables to optimize structural and vibrational performances. The results obtained not only confirm the auxetic behavior of these designs but demonstrate their excellent ability to open robust complete PBGs. By exploiting Iso Frequency Contours (EFCs), we have modeled the phenomenon of self-collimation. This mechanism proves that these PCs can naturally focus and guide vibrational energy along precise trajectories, offering a promising trajectory for the unconventional manipulation of waves. This project opens concrete prospects for the development of high-precision acoustic insulation and filtering devices. Thu, 18 Dec 2025 00:00:00 GMT http://depot.umc.edu.dz/handle/123456789/14859 2025-12-18T00:00:00Z http://depot.umc.edu.dz/handle/123456789/14858 Contributions to fractional-order fault-tolerant control of nonlinear systems. Daoudi, Islam; Chemachema, Mohamed The primary aim of this thesis is to develop adaptive control strategies tailored for specific categories of uncertain single-input single-output (SISO) and interconnected multi-input multi-output (MIMO) fractional-order nonlinear systems. The investigation includes the analysis of the effect of saturation on the control inputs along with the external disturbances on the dynamics of systems. In all the proposed methodologies, neural networks or fuzzy logic systems serve as universal approximators to estimate the unknown nonlinear dynamics of the systems. The architectures of the proposed controllers address the well-known challenges associated with complexity explosion while circumventing the conventional back-stepping technique thanks to the introduction of a new fractional systems transformation into the controllable Bronovsky form. By using the implicit function theorem and the strictly positive real (SPR) property, output feedback approaches become feasible. Compared to similar approaches, the proposed adaptive neural/fuzzy controllers exhibit minimal online learning parameters. Furthermore, the integration of the Eventtriggered mechanism optimizes resource utilization by updating control actions only when necessary, thereby reducing computational burden and communication overhead. Additionally, stability analysis of all control loops is conducted using the Lyapunov method, and simulation results are provided for each scheme to demonstrate its efficacy. Mon, 22 Dec 2025 00:00:00 GMT http://depot.umc.edu.dz/handle/123456789/14858 2025-12-22T00:00:00Z http://depot.umc.edu.dz/handle/123456789/14857 Conception d’un coupleur optique Chergui, Imane; Labbani, Amel The primary objective of this thesis is to develop models and optimize the performance of optical switches and power splitters based on directional couplers. These devices are essential components in optical telecommunication systems, as they enable the switching and splitting of optical signals into multiple paths. A key advantage of directional couplers over conventional switches and power splitters is their significantly lower radiation losses, which enhance system efficiency. To analyze the optical properties and evaluate the performance of these devices, simulations were conducted using RsoftCAD software, employing the FiniteDifference Time-Domain (FDTD) method and the Plane Wave Expansion (PWE) method. The coupler consists of two linear waveguides separated by a row of silicon columns. Various technologies have been proposed to enhance the performance of photonic crystal-based directional couplers (DCs) and minimize the coupling length between the two waveguides. The proposed directional coupler replaces the central row of silicon rods with core/shell (C/S) particles, which are created by perforating the silicon rods to introduce air holes. The internal and external radii of the silicon rods in the central row of the C/S structure are denoted as rin and rout, respectively. The modified directional coupler reduces the coupling length (Lc) to 5a, where a is the lattice constant. Simulation results show that increasing the inner radius rin enhances the coupling coefficient while reducing the coupling length (Lc). The first devices designed using the new directional coupler architecture are 2×2, 3×3, and 4×4 optical switches based on photonic crystals. The basic structure consists of rows of silicon (Si) rods arranged in an air medium on a hexagonal lattice. The influence of varying the inner and outer rods, as well as modifications to the permittivity or refractive index of the core and shell, on the coupling length and output power was also studied. Simulation results demonstrate that the three proposed switches exhibit high normalized transmission, negligible reflection, fast delay times, and low crosstalk (measured in dB). The areas of the 2×2, 3×3, and 4×4 optical switches are 185.35 μm², 273.53 μm², and 356.53 μm², respectively.The modified directional coupler reduces the coupling length (Lc) to 5a, where a is the lattice constant. Simulation results show that increasing the inner radius rinenhances the coupling coefficient while reducing the coupling length (Lc). The first devices designed using the new directional coupler architecture are 2×2, 3×3, and 4×4 optical switches based on photonic crystals. The basic structure consists of rows of silicon (Si) rods arranged in an air medium on a hexagonal lattice. The influence of varying the inner and outer rods, as well as modifications to the permittivity or refractive index of the core and shell, on the coupling length and output power was also studied. Simulation results demonstrate that the three proposed switches exhibit high normalized transmission, negligible reflection, fast delay times, and low crosstalk (measured in dB). The areas of the 2×2, 3×3, and 4×4 optical switches are 185.35 μm², 273.53 μm², and 356.53 μm², respectively. Moreover, the proposed switches are compact and can be integrated into optical telecommunication systems. The second set of devices in this thesis focuses on the design and modeling of 1×2 and 1×4 Y-junction power splitters, based on the new directional coupler architecture. These devices split the signal into two or four paths with minimal radiation losses, particularly in curved regions. An ideal power splitter uniformly divides the optical signal injected at its input into multiple outputs without any radiation loss. To minimize radiation losses while maximizing total transmission, an optimization technique was proposed that involved modifying the inner radii of the (C/S) structure. The optical properties of the optimized splitters are significantly improved, achieving total transmission of up to 99% of the incident light. The sizes of the proposed 1×2 and 1×4 Y-junction dividers are 177.63 μm² and 449.45 μm², respectively. These devices are highly compact and deliver excellent splitting performance, making them particularly suitable for applications in optical telecommunications and photonic integrated circuits. Thu, 27 Nov 2025 00:00:00 GMT http://depot.umc.edu.dz/handle/123456789/14857 2025-11-27T00:00:00Z