Alain Soup Tewa Kammogne

This study conducts a comparative analysis of sliding mode control (SMC) and fractional-order sliding mode control (FOSMC) for application in antilock braking systems (ABS). Based on foundational principles of theoretical mechanics, the ABS dynamics are modeled as a single-input system to analyze wheel-slip regulation under diverse and variable road conditions. Both the conventional SMC and the proposed FOSMC are designed using a Lyapunov-based approach to ensure robust stability, with the latter incorporating fractional-order derivatives to refine the sliding surface and dynamic response. The conventional SMC method, while demonstrating strong robustness and disturbance rejection capabilities, is found to induce persistent chattering during transient phases, which can compromise system reliability and actuator longevity. By contrast, the FOSMC controller enhances transient behavior by attenuating chattering and yielding smoother, more consistent wheel-slip tracking. The inclusion of fractional-order terms contributes to faster convergence and improved adaptation to abrupt changes in road friction, though it introduces increased computational complexity. Numerical simulations validate the performance of both controllers across multiple driving scenarios, including dry, wet, and icy road conditions. Results confirm that FOSMC significantly reduces chattering, accelerates system convergence, and maintains stable braking performance with greater consistency compared to conventional SMC, establishing its potential for implementation in advanced ABS designs.

An innovative model of a fractional order two neuron-based memristive autapses Hopfield Neural Network (HNN) impacted by external electromagnetic radiation is described in this study. Firstly, the system mentioned above is modeled in the fractional-order form. The Adomian decomposition is the foundation of the numerical simulation technique. In terms of the stability requirement of fractional-order systems, the bifurcation tools connected to Lyapunov exponents show the system’s rich dynamical behavior, including a line of equilibrium which are all unstable with regards to the stability condition of fractional-order systems. Investigating the effect of the fractional order (q) on the dynamics of the system is of particular interest. It reveals that, for certain sited periodic regions alone, the system is chaotic throughout the variation of (q). Furthermore, as the several bifurcation diagrams demonstrate, the Memristor Autapse and external electromagnetic radiation have a significant impact on the dynamics of the suggested system. Lastly, a biomedical image encryption approach based on the HNN system is described within the framework of digital cryptography. This scheme offers results with a greater level of security than those achieved by traditional chaos-based communications methods. Image data can be protected in real-world information exchange using this suggested encryption scheme, which is successfully resistant to both statistical and entropy attacks.

This paper focuses on the estimation of the nonlinear encoding and responses of a photosensitive Fitz Hugh Nagumo (FHN) neuron-based-meminductor and provides a relevant analysis of its phase synchronization. In the pattern, a Fitz Hugh–Nagumo neuron connected to a meminductor is activated by a photocell, and a time-varying current source is generated by the presence of external optical signals. This coupling is a benchmark circuit with memory similar to artificial eyes with the ability to capture and encode external signals. It is designed with the aim of studying the dynamics of a neuron with a memory effect highlighted through the meminductor. An appropriate dynamical analysis is provided using standard indicators such as bifurcations to point out thorough transitions and the nature of the electrical neuronal activities. Some couplings between two FHN neurons with meminductor using hybrid synapses composed of passive electronic components are achieved. Relevant tools are used to analyze the stability of the synchronization which gives prominent details on the selection of the appropriate coupling. The energy balance of the external system is evaluated which gives the effort to achieve encoding signals and also proves the feasibility of the proposal in real-time implementation. Simulations are performed on FPGA. The results present a good agreement. In many engineering applications, the detection of optical signals is inescapable as well as the synchronization of its signals for the transmission of the stimuli. These results could be useful for the designer.

We generate a new hyperchaotic four-leaf system by inserting a state feedback control to the 3-D Vaidyanathan-Rhif chaotic four-leaf system (Vaidyanathan and Rhif, 2017). The new hyperchaotic system developed in this work has three quadratic non-linearities and two positive Lyapunov exponents. Bifurcation analysis points coexisting bifurcations and multiple attractors for the new 4-D hyperchaotic four-leaf system. Next, we construct an electronic circuit model using MultiSim (Version 13.0) for implementing the new 4-D hyperchaotic four-leaf system. Embedded and non-embedded implementations of chaotic and hyperchaotic systems are vital to increase their usability in many engineering applications since those FPGA designs can be linked to the digital world surrounding us in a direct manner. An ARM-FPGA-based hardware implementation of the 4-D hyperchaotic four-leaf system is given in detail, showing a good agreement between numerical and experimental results.

In this paper, a nonlinear Josephson junction (JJ) based-Wien bridge circuit is analyzed and coupled in order to obtain synchronization through passive components. The electrical equations governing the operation of our circuit are obtained using the laws of electrical circuit analysis. Chaotic phenomenon is demonstrated in the proposed circuit using relevant indicators such as the phase portraits, bifurcation and the corresponding Lyapunov diagram. Several coupling topologies are considered to achieve the phase synchronization that provides a better understanding of the distribution of energy in the overall system. Additionally, the effect of the noise is considered which considerably brings an added value to the dynamic of the phase synchronization between oscillators. Full synchronization is observed when the resistor is connected in parallel with the inductor or capacitor while different results are obtained when the resistor is connected in series with the capacitor or inductor. Finally, fine-tuning and selection of coupling coefficients reflects a migration toward synchronization between two Josephson junction based-Wien circuits that imply the self-adaptation of the synapse when two types of synapses are active simultaneously.