Qualitative Theory of Dynamical Systems最新文献

A sofic shift is a shift space consisting of bi-infinite labels of paths from a labelled graph. Being a dynamical system, the distribution of its closed orbits may indicate the complexity of the shift. For this purpose, prime orbit and Mertens’ orbit counting functions are introduced as a way to describe the growth of the closed orbits. The asymptotic behaviours of these counting functions can be implied from the analyticity of the Artin–Mazur zeta function of the shift. Its zeta function is expressed implicitly in terms of several signed subset matrices. In this paper, we will prove the asymptotic behaviours of the counting functions for sofic shifts via their zeta function. This involves investigating the properties of the said matrices. Suprisingly, the proof simply uses some well-known facts about sofic shifts, especially on the minimal right-resolving presentations. Furthermore, we will demonstrate this result by revisiting the case for periodic-finite-type shifts, which are a particular type of sofic shifts. At the end, we will briefly discuss the application of our finding towards the finite group and homogeneous extensions of a sofic shift.

In this paper, we study the maximum number of limit cycles for the piecewise smooth system of differential equations (dot{x}=y, dot{y}=-x-varepsilon cdot (f(x)cdot y +textrm{sgn}(y)cdot g(x))). Using the averaging method, we were able to generalize a previous result for Liénard systems. In our generalization, we consider g as a polynomial of degree m. We conclude that for sufficiently small values of (|{varepsilon }|), the number (h_{m,n}=left[ frac{n}{2}right] +left[ frac{m}{2}right] +1) serves as a lower bound for the maximum number of limit cycles in this system, which bifurcates from the periodic orbits of the linear center (dot{x}=y), (dot{y}=-x). Furthermore, we demonstrate that it is indeed possible to obtain a system with (h_{m,n}) limit cycles.

This paper concerns the polynomial-logarithmic stability and stabilization of time-varying control systems. We present sufficient Lyapunov-like conditions guaranteeing this polynomial-logarithmic stability with applications to several linear and nonlinear control systems.

In this paper, we study a class of non-autonomous piecewise differential equations defined as follows: (dx/dt=a_{0}(t)+sum _{i=1}^{n}a_{i}(t)|x|^{i}), where (nin mathbb {N}^{+}) and each (a_{i}(t)) is real, 1-periodic, and smooth function. We deal with two basic problems related to their limit cycles (big (text {isolated solutions satisfying} x(0) = x(1)big )). First, we prove that, for any given (nin mathbb {N}^{+}), there is no upper bound on the number of limit cycles of such equations. Second, we demonstrate that if (a_{1}(t),ldots , a_{n}(t)) do not change sign and have the same sign in the interval [0, 1], then the equation has at most two limit cycles. We provide a comprehensive analysis of all possible configurations of these limit cycles. In addition, we extend the result of at most two limit cycles to a broader class of general non-autonomous piecewise polynomial differential equations and offer a criterion for determining the uniqueness of the limit cycle within this class of equations.

In this paper, we introduce and investigate a Hadamard-type fractional differential equation on the interval ((1, infty )) equipped with a new class of logarithmic type integro-initial conditions. We apply the Leggett–Williams fixed point theorem and the concept of iterative positive solutions to establish the existence of solutions for the problem at hand. Our results are new and enrich the literature on Hadamard-type fractional differential equations on the infinite domain. Examples illustrating the main results are presented.

These days, watching the shallow water waves, people think about the nonlinear Broer-type models, e.g., a (2+1)-dimensional generalized Broer-Kaup system modeling, e.g., certain nonlinear long waves in the shallow water. For that system, with reference to, e.g., the wave height and wave horizontal velocity, this paper avails of symbolic computation to obtain (A) an auto-Bäcklund transformation with some solitons; (B) a group of the scaling transformations and (C) a group of the hetero-Bäcklund transformations, to a known linear partial differential equation, from that system. Results rely on the coefficients in that system

In this work, we focus on the application of epidemic approaches to computer viruses and investigate the dynamic transmission of multiple viruses, aiming to reduce computer destruction. Our goal is to create and examine computer viruses using the Atangana-Baleanu sense, which is employed in the fractional difference model for the spread of computer viruses. It included removable storage devices and external computer peripherals that were infected with computer viruses. The applications of fixed-point theory and iterative techniques are employed to analyze the existence and uniqueness results concerning the suggested model. Moreover, we extend several kinds of Ulam’s stability results for this discrete model. To demonstrate the implications of changing the fractional order in this instance of numerical simulation, we employed the Atanagana–Baleanu technique. The graphical outcomes validate our theoretical findings, which we used to evaluate the impact of infected external computers and removable storage devices on computer viruses.

In this work, we focus on the relative controllability and Hyers–Ulam stability of Riemann–Liouville fractional delay differential system of order (alpha in (1,2)). Firstly, for the linear system based on Mittag-Laffler matrix function, we define a controllability Grammian matrix to judge whether the system is relatively controllable. Additionally, with the aid of Krasnoselskii’s fixed point theorem, sufficient conditions for the relative controllability of the corresponding semilinear system is also studied. Furthermore, we used Grönwall’s inequality to investigate Hyers–Ulam stability for Riemann–Liouville fractional semilinear delay differential equations. Lastly, three instances are provided to verify that our theoretical results are accurate.

Studies on the shallow water waves belong to the cutting-edge issues in sciences and engineering. In this paper, introducing symbolic computation, for a generalized nonlinear shallow water wave equation, with respect to the displacement and velocity of the water, we establish an auto-Bäcklund transformation with some solitonic solutions, as well as a set of the similarity reductions, the latter of which ought to be focused towards a known ordinary differential equation. Our results are seen to tie to the gravitational force and wave height.

The bifurcations and monotonicity of the period function of the Lakshmanan–Porsezian–Daniel equation with Kerr law of nonlinearity are discussed. Firstly, by the traveling wave transformations, the Lakshmanan–Porsezian–Daniel equation is reduced to the planar Hamiltonian system whose Hamiltonian function includes a 6-th degree polynomial. Then we give the phase portraits of the Hamiltonian system, and some traveling waves including dark wave solutions, kink and anti-kink solutions and periodic solutions are constructed by using the bifurcation method of dynamical systems. Furthermore, we discuss the monotonicity of the period function of periodic wave solutions by using some Lemmas proposed by Yang and Zeng (Bull Sci Math 133(6):555-557, 2009). Finally, some numerical simulations are presented.