نوع مقاله : مقاله پژوهشی
نویسندگان
1 دانشگاه شهید مدنی آذرباجان
2 عضو هیات علمی دانشگاه دانشگاه شهید مدنی آذربایجان
چکیده
کلیدواژهها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
In this paper, an SCIRS epidemic model with Caputo fractional derivatives and time delay is investigated. In this model, the role of temporary immunity is explicitly modeled such that recovered individuals lose their immunity after a certain period and return to the susceptible population. The aim of the model is to analyze the dynamics of COVID-19 transmission by incorporating the system’s memory and delays in treatment and immunity return. Based on the results reported in 29, ٍxistence and uniqueness of solution to proposed model are assumed. Subsequently, stability of equilibrium points is studied in the absence of time delay, and conditions for asymptotic stability of endemic equilibrium are provided. Next, effect of time delay on the system’s dynamic stability is analyzed, and conditions for occurrence of a Hopf bifurcation are derived. For numerical solution of model, a method based on the Adams–Bashforth–Moulton predictor-corrector algorithm is developed. Finally, numerical simulations are performed using real-world COVID-19 data (during the period from June 15 to August 4, 2022) which were obtained from official sources published by the Global Ministry of Health.
The simulation results indicate that fractional-order model not only better fits the real data, but also shows superior capability in capturing memory-dependent behaviors, fluctuations in the infected population, and the effect of waning immunity, compared to classical integer-order models. Stability analysis reveals that reducing the delay in immunization, strengthening long-term immunity, and maintaining preventive measures such as social distancing can prevent epidemic oscillations and guide the system trajectory toward the disease-free equilibrium.
کلیدواژهها [English]
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