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Fractional-order modeling of dengue dynamics: exploring reinfection mechanisms with the Atangana–Baleanu derivative
(2025-08-01)
Lamwong, Jiraporn
;
Pongsumpun, Puntani
Dengue fever poses ongoing public health challenges due to its complex reinfection dynamics and antibody-dependent enhancement (ADE). To address limitations in classical models, this study proposes a novel fractional-order model utilizing the Atangana–Baleanu–Caputo derivative to capture memory and non-local effects inherent in dengue transmission. The model explicitly incorporates reinfection mechanisms and stages of infection, offering a more accurate depiction of disease progression. The existence and uniqueness of solutions are established using fixed-point theory, and the global stability of equilibria is analyzed via Lyapunov methods. Model fitting with real-world data from Thailand in 2023 confirms predictive accuracy, while sensitivity analysis identifies the biting and mosquito mortality rates as critical parameters influencing the basic reproduction number. This framework enhances the realism of epidemic models and provides actionable insights for designing targeted public health interventions in dengue-endemic regions.
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FINITE-TIME NONLINEAR SPEED CONTROLLER OF PERMANENT MAGNET SYNCHRONOUS MOTOR USING C MEX S-FUNCTION
(2025-07-31)
Cholahan, Varin
;
Rattanakun, Kritsana
;
Tangsrirat, Worapong
Permanent magnet synchronous motor (PMSM) has high torque and possesses a simple structure relative to its capacity. It has been popularly applied in numerous industrial applications. Nonetheless, PMSM is sensitive to both internal and external disturbances. It exhibits significant nonlinearity and functions as a multi-variable coupling system. Therefore, a control system capable of delivering superior performance must be nonlinear. Owing to its considerable robustness capability, the sliding-mode control (SMC) technique is extensively utilized in this research. This work also demonstrates the use of C Mex S-function, the most efficient code-oriented tool, to simulate the operation of nonlinear systems. The C-Mex S-function is an effective and practical approach for developing models within the SIMULINK/MATLAB user interface environment and utilizing its requisite capabilities. Consequently, the nonlinear controller established in this study is carried out via the C-Mex S-function. Let’s manipulate the characteristics of the PMSM to converge to equilibrium within a finite time period. The tracking speed signal can be quickly followed with a high robustness against disturbances, uncertainties, and unmodeled variables. In addition, the Lyapunov function is employed to assess the stability of the developed SMC controllers, whereby the stable convergence property is demonstrated and proven. To illustrate the performance of the continuous fast-terminal sliding-mode control scheme, some simulation tests are performed on the speed regulation of the PMSM drive plant. The simulations are presented as code resembling the C programming language within SIMULINK/MATLAB. The findings show that the proposed controller achieves a speed overshoot of less than 3%, a settling time of approximately 0.15 seconds, and a steady-state error of less than 0.5 rad/s under a load torque of 1.5 Nm. These results highlight the high performance and robustness of the proposed speed controller.
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Hamiltonian-Based Approach to Enhance the Stability of Hybrid Fuel Cell and Supercapacitor Sources
(2025-01-01)
Mungporn, Pongsiri
;
Kamnarn, Uthen
;
Yodwong, Burin
;
Khomfoi, Surin
;
Pierfederici, Serge
This article aims to study an improved large-signal stability for fuel cell (FC) and supercapacitor (SC) hybrid sources, employing the enhanced Hamiltonian control law. This novel approach addresses the inherent challenges in the dynamic operation of such hybrid systems, characterized by rapid load changes [i.e., constant power load (CPL)] and energy fluctuations. Grounded in energy-based control theory, the Hamiltonian control law accurately manages the energy exchange between the FC, SC, and external load aiming to improve system stability and response efficiency. A comprehensive test bench setup, including a real FC, an SC bank, and programmable loads to simulate the electrical load (i.e., CPL, constant resistive load, and constant current load), was developed to evaluate performance under various operational conditions. The results demonstrate that Hamiltonian-based control significantly enhances the system’s damping properties, ensuring a smoother response to load variations and enhanced stability across different scenarios.
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Robust Constant Exponent Coefficient Fixed-Time Control Based on Finite-Time Extended Sliding Mode Observer of Permanent Magnet Synchronous Motors
(2023-11-01)
Cholahan, Varin
;
Wongvanich, Napasool
;
Tangsrirat, Worapong
This paper presents the Robust Constant Exponent Coefficient Fixed-Time Control (CECFSMC), an innovative control technique for precisely regulating the speed of a permanent magnet synchronous motor (PMSM) by utilizing fixed-time stability with constant exponent coefficients to provide not only faster convergence but also in a specific period of time. The effect of chattering is also lessened. To ensure that the designed controller produces the desired performance under bounded disturbances, a finite-time extended sliding-mode observer (ESMO) is also designed to estimate the PMSM velocity while also estimating lumped load disturbances. The considered PMSM is the surface-mounted PMSM. Finally, a numerical simulation with PMSM drive shows good robustness against load disturbances, better convergence, and a reaching time of less than 2 s, thereby demonstrating that the proposed fixed-time constant exponent coefficient offers good performance and is much simpler than the conventional finite-time method.

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