Hadil Alhazmi

This paper proposes an adaptive fuzzy prescribed-time output feedback control approach for strict-feedback nonlinear cyber–physical systems (CPSs) subjected to malicious attacks, output constraints, and backlash-like hysteresis. To approximate unknown system nonlinearities, fuzzy logic systems (FLSs) are employed. A practical prescribed-time stability condition is introduced, based on which a prescribed-time output feedback control scheme is constructed using Lyapunov-based analysis and the backstepping technique. The proposed control strategy guarantees that both the tracking error and the observation error converge to small neighborhoods around zero within a prescribed time. Furthermore, all signals within the closed-loop system remain bounded, and the tracking error is driven to a constrained target region near the origin. The effectiveness and robustness of the proposed method are validated through a practical example.

This paper investigates the adaptive prescribed performance fixed-time control problem for uncertain strict-feedback nonlinear systems in the presence of unknown control coefficients and actuator faults. A switching-based control strategy is developed to address the uncertainty in control coefficients, where adaptive parameters are adjusted online according to design requirements. To regulate the transient and steady-state behavior, a fixed-time prescribed performance function is incorporated into the control design, ensuring that the tracking error evolves within predefined bounds. The command filter technique is employed to simplify the backstepping procedure and avoid the issue of complexity growth, while filter-induced errors are compensated using auxiliary signals. Rigorous Lyapunov analysis establishes that all closed-loop signals remain bounded and that the tracking error converges to a small neighborhood of zero within a fixed time, independent of initial conditions. The effectiveness of the proposed method is demonstrated through numerical simulations and a practical example.

This paper proposes a new spectral three‐term conjugate gradient (STTCG) method for solving large‐scale unconstrained optimization problems. The proposed method integrates the Liu–Storey conjugate gradient parameter with a modified three‐term correction and a safeguarded Barzilai–Borwein spectral scaling strategy to enhance both robustness and computational efficiency. The resulting search direction satisfies the sufficient descent condition independently of the line search procedure, while its conjugacy property is established under a positive curvature condition. Furthermore, the global convergence of the proposed method is proved under standard assumptions. Extensive numerical experiments on 120 benchmark test problems with dimensions ranging from n = 2 to n = 500, 000 demonstrate that STTCG is competitive with five state‐of‐the‐art conjugate gradient methods in terms of the number of iterations, function evaluations, and CPU time. To further demonstrate its practical applicability, the proposed method is employed in the trajectory tracking of a four‐degrees‐of‐freedom (4DOF) robotic manipulator, where it exhibits accurate tracking performance and favorable computational efficiency. MSC2020 Classfication: 65K05 | 90C52 | 90C56 | 94A08

In this study, we work on a Holling–Tanner prey‐predator (HTPP) model by incorporating the impact of predator cannibalism and later introducing a delay in prey growth. We first examine its behavior without delay: we identify equilibrium points, describe their stability, and explain when the system remains stable or goes into oscillation. Then we add a time lag in the prey growth, which captures the natural lag in biological systems. We establish positivity, and by applying the Routh–Hurwitz criterion, we obtain explicit criteria for local stability and also prove global stability (GS) by applying a Lyapunov approach. Numerical simulations indicate that populations can converge in the ordinary model but oscillate indefinitely as soon as the delay passes a threshold. Aside from analysis, we also plot a detailed graph to show the findings. The results validate that delay significantly destabilizes the system, and cannibalism determines the long‐term dynamics.

In this paper, we use the unified solver technique to investigate the effective irregular wave propagations in dispersive and dissipative modes via the (2 + 1)-dimensional Fokas model, which describe a simple extension of the nonlinear Schrödinger equation. Using a complex traveling wave transformation, the Fokas model is transformed into a nonlinear ordinary differential equation. The unified solver method subsequently produces several kinds of solitary wave solutions. More precisely, it provides solutions in trigonometric, hyperbolic, dissipative, rational, solitonic, and super soliton forms. Among the many benefits of the given technique are the reduction of complex computations and the concise presentation of important results. To demonstrate the wave structures for the dispersive and dissipative Fokas model, two-dimensional, three-dimensional, and contour plots of selected solutions are created utilizing the MATLAB software. We also demonstrate how physical parameters affect the acquired solutions’ behavior. The suggested method could be improved to address more complex applied science problems.

In this study, we used the Riccati–Bernoulli technique to generate new solitary structures for the model of the nonlinear two-dimensional Schrödinger equation (NTDNLSE) with a source term. These structures included rational, periodic, solitary, explosive, dissipative, and blow-up solitons. To demonstrate the shape of the obtained solutions for suitable free parameter values, a few 2D and 3D charts are displayed. The dynamical and phase portrait behaviors with the aid of model parameters controlled the type of obtained NTDNLSE solitary solutions. The properties of NTDNLSE structure solutions that depend on the Kerr, drift, and dispersion have been investigated. Many fluid and space plasma applications depend on the dynamical behaviors of these solutions. The results show how straightforward and quick this method is for constructing elaborate nonlinear wave patterns and rich exact solutions to nonlinear equations in mathematical physics.

This article analyzes and examines the nonlinear Maccari’s equations with a noise term using the powerful sub-equation mathematical approach. Several significant solitary and rational solutions have been provided. These solutions are crucial in a number of fields, such as superfluid, optical fiber communication, and space-confined plasma waves. The effects of model parameters on the obtained solutions’ features have been discussed. The randomness parameter affects the envelope, solitonic structures, and energy properties. It was reported that by increasing the random parameter, Brownian isolated driving shock waves with random amplitude were produced. Finally, the method described here may be applied to many nonlinear systems and new energy trends in natural science.

For many nonlinear applications described by the dynamics of nonlinear Schrödinger equation with higher-order terms (HONLSE) such as nonlinear optics, space plasma physics molecular biology, astrophysics, quantum mechanics, superfluid, fluid mechanics, and fiber optics communications, a unique closed-form solution have been obtained using energy equation. In addition, some new solitary solutions HONLSE have been obtained via the unified solver method. The resultant solutions behave as breathers, super solitons, envelope breathers, blow up, localized super waves, periodical super shock, train super solitons, and shock structures. The modulations of Kerr nonlinear, chromatic dispersive, and wave packet drift parameters on the wave characteristics of the obtained solutions have been investigated. It was reported that the model parameters affect the amplitude, steepness, and width of the resultant structures. The provided solution can be used as a box solver for a variety of natural science systems described by distinct nonlinear equations.

Non‐Newtonian fluid plays a vital role in the field of manufacturing and engineering sector, because of its immense heat transfer rate. The two‐dimensional incompressible unsteady Maxwell nanofluid thin‐film flow with MHD and viscous dissipation over an inclined surface is investigated. One of the mechanisms in the second law of thermodynamics, that is irreversibility which also analyzed. The Maxwell nanofluid thin film energy and motion equations in the additional information have been turned into a coupled differential system of the third order. The transformed ODE equations are further evaluated by using the Homotopy Analysis Method (HAM). The variations of entropy rate, velocity, Bejan number and temperature field with the various emerging parameters are analyzed. This could potentially lead to the development of solar energy systems that are both affordable and highly efficient, so enabling the more efficient use of renewable energy sources and reducing our dependence on fossil fuels.