In this letter, we deal with a class of memristor-based neural networks with distributed leakage delays. By applying a new Lyapunov function method, we obtain some sufficient conditions that ensure the existence, uniqueness, and global exponential stability of almost periodic solutions of neural networks. We apply the results of this solution to prove the existence and stability of periodic solutions for this delayed neural network with periodic coefficients. We then provide an example to illustrate the effectiveness of the theoretical results. Our results are completely new and complement the previous studies Chen, Zeng, and Jiang ( 2014 ) and Jiang, Zeng, and Chen ( 2015 ).

All the time, differential dynamical models with delay has witness a tremendous application value in characterizing the internal law among diverse biological populations in biology. In the current article, on the basis of the previous publications, we formulate a new Lotka–Volterra commensal symbiosis system accompanying delay. Utilizing fixed point theorem, inequality tactics and an appropriate function, we gain the sufficient criteria on existence and uniqueness, non-negativeness and boundedness of the solution to the formulated delayed Lotka–Volterra commensal symbiosis system. Making use of stability and bifurcation theory of delayed differential equation, we focus on the emergence of bifurcation behavior and stability nature of the formulated delayed Lotka–Volterra commensal symbiosis system. A new delay-independent stability and bifurcation conditions on the model are presented. By constructing a positive definite function, we explore the global stability. By constructing two diverse hybrid delayed feedback controllers, we can adjusted the domain of stability and time of appearance of Hopf bifurcation of the delayed Lotka–Volterra commensal symbiosis system. The effect of time delay on the domain of stability and time of appearance of Hopf bifurcation of the model is given. Matlab experiment diagrams are provided to sustain the acquired key outcomes.

In the literature [16], the COVID-19 model has been constructed using deterministic approach. The present manuscript examines a stochastic model designed to capture the interplay between COVID-19 and varying infection rates on disease dynamics. We present the necessary criteria for a global solution to the considered model to exist and be unique. To illustrate several outcomes pertaining to the ergodic properties of the given system, the we utilize nonlinear analysis. Furthermore, the model undergoes simulation and is compared with deterministic dynamics. To verify the efficacy of the considered model and demonstrate its utility, we compare the dynamics of the infected population to real statistical data from multiple countries, such as the United Kingdom, Australia, Spain, and India. The proposed model has proven to be a reliable and effective tool for understanding the intricate nature of COVID-19 dynamics. Moreover, we provide a visually striking depiction of the impact of different infection rates on the propagation of the model under investigation. This visualization provides valuable insight into the multifaceted nature of the pandemic and significantly contributes to the comprehension of COVID-19 dynamics.

Formulating suitable dynamical models to describe the interplay of different chemical substance in biology and chemistry is a very interesting topic. In this article, we set up a new plankton population dynamical system accompanying delay. Taking advantage of fixed point theorem and appropriate function, we derive the criteria on existence and uniqueness, boundedness of the solutions of the established plankton population dynamical system. By applying Hopf bifurcation and stability theorem of delayed dynamical system, we analyze the emergence of Hopf bifurcation and stability trait of the established plankton population dynamical system. Novel delay-independent criteria guaranteeing the emergence of Hopf bifurcation and stability of the system are derived. By virtue of two different controllers, we have effectively controlled the time of occurrence of Hopf bifurcation and stability domain of the established system. The influence of time delay on Hopf bifurcation and stability of the system is shown. The study shows that when the delay crosses a critical value, then Hopf bifurcations of the established plankton population dynamical system and its controlled systems arise. Numerical experiment outcomes are included to support the derived main fruits. The derived results of this article are completely new and have important theoretical value in balancing and controlling the concentrations of distinct chemical substances.