Nonexistence Of Periodic Solutions Research Articles

Sobolev hyperbola for periodic Lane–Emden heat flow system in N spatial dimension

The well-known Lane–Emden conjecture indicates that, for the elliptic Lane–Emden system −Δu=vp, −Δv=uq in RN, the Sobolev hyperbola 1p+1+1q+1=N−2N is expected as the critical curve for the existence and nonexistence of entire solutions. In this paper, we study the periodic Lane–Emden heat flow system ut−Δu=a(t)vp, vt−Δv=b(t)uq in a bounded domain Ω of RN, subject to homogeneous Dirichlet boundary condition. We will show that the Sobolev hyperbola is also a critical curve for the existence and nonexistence of periodic solutions. Moreover, if pq=1, the nontrivial periodic solutions may exist or not exist.

On the Entropy Formulas and Solitons for the Ricci-Harmonic Flow

This paper is concerned with entropy monotonicity formulas and classification of gradient almost soliton for Ricci-harmonic flow. The new entropy formulas introduced here are monotone in general along the flow and constant exactly on shrinker or expander as the case may be. The consequence of this is the nonexistence of periodic solutions except those that are gradient solitons. Furthermore, the paper discusses gradient almost Ricci-harmonic soliton with respect to a fixed metric, not minding the dynamical nature of the flow but treating the defining elliptic equations and relying on analytic techniques. Finally, we are able to classify gradient almost Ricci-harmonic solitons.

Nonlinear state-dependent feedback control of a pest-natural enemy system

The numbers of pests and of natural enemies released to control them as part of integrated pest management strategies are density dependent. Therefore, the numbers of natural enemies to be released and the rate at which they kill pests should depend on their densities when the number of the pest population has reached the economic threshold. Bearing this in mind, a classic Lotka–Volterra system but with nonlinear state-dependent feedback control tactics is proposed and analysed in this paper. Furthermore, the definition and properties of the Poincare map which is defined in the phase set were investigated for various cases, allowing us to address the existence and global stability of an order-1 periodic solution of the model with nonlinear feedback control. Moreover, the existence and nonexistence of periodic solutions with an order larger than 2 or 3 are also discussed. The modelling methods and analytical techniques developed could be widely used and applied in other systems with threshold control such as the glucose insulin regulatory system.

Note on periodic solutions of fractional differential equations

The existence and nonexistence of periodic solutions are discussed for fractional differential equations by varying the lower limits of Caputo derivatives. The developed approach is illustrated on several examples.

Relationship between integer order systems and fractional order system and its two applications

Existence of periodic solutions and stability of fractional order dynamic systems are two important and difficult issues in fractional order systems U+0028 FOS U+0029 field. In this paper, the relationship between integer order systems U+0028 IOS U+0029 and fractional order systems is discussed. A new proof method based on the above involved relationship for the non existence of periodic solutions of rational fractional order linear time invariant systems is derived. Rational fractional order linear time invariant autonomous system is proved to be equivalent to an integer order linear time invariant non-autonomous system. It is further proved that stability of a fractional order linear time invariant autonomous system is equivalent to the stability of another corresponding integer order linear time invariant autonomous system. The examples and state figures are given to illustrate the effects of conclusion derived.

Transition of interaction outcomes in a facilitation-competition system of two species.

A facilitation-competition system of two species is considered, where one species has a facilitation effect on the other but there is spatial competition between them. Our aim is to show mechanism by which the facilitation promotes coexistence of the species. A lattice gas model describing the facilitation-competition system is analyzed, in which nonexistence of periodic solution is shown and previous results are extended. Global dynamics of the model demonstrate essential features of the facilitation-competition system. When a species cannot survive alone, a strong facilitation from the other would lead to its survival. However, if the facilitation is extremely strong, both species go extinct. When a species can survive alone and its mortality rate is not larger than that of the other species, it would drive the other one into extinction. When a species can survive alone and its mortality rate is larger than that of the other species, it would be driven into extinction if the facilitation from the other is weak, while it would coexist with the other if the facilitation is strong. Moreover, an extremely strong facilitation from the other would lead to extinction of species. Bifurcation diagram of the system exhibits that interaction outcome between the species can transition between competition, amensalism, neutralism and parasitism in a smooth fashion. A novel result of this paper is the rigorous and thorough analysis, which displays transparency of dynamics in the system. Numerical simulations validate the results.

Existence and nonexistence of periodic solution and Hopf bifurcation of a tourism-based social–ecological system

This paper is devoted to analyze dynamical behavior of a four-dimensional nonlinear tourism-based social–ecological system by using the Hopf bifurcation theory. Our purpose is using a criterion based on the Routh–Hurwitz criterion for existence of a region for Hopf bifurcation. Because existence of Hopf bifurcation and therefore bifurcated periodic solutions helps us to show an interesting type of coexistence between mass-tourists and eco-tourists through a periodic pattern, although they have different effects on environmental quality. Furthermore, numerical simulations are carried out to support our theoretical results and show sustainability of tourism. In fact by simulation we indicate a coexistence between mass-tourists and eco-tourists, the existence of chaotic behavior and sustainability of tourism industry.Moreover another criterion, Bendixson's negative criterion, which is based on the connection between compound matrices and ordinary differential equations is applied to prove the nonexistence of periodic orbits and then nonexistence of Hopf bifurcation.

An SIRS Epidemic Model with Vital Dynamics and a Ratio-Dependent Saturation Incidence Rate

This paper presents an investigation on the dynamics of an epidemic model with vital dynamics and a nonlinear incidence rate of saturated mass action as a function of the ratio of the number of the infectives to that of the susceptibles. The stabilities of the disease-free equilibrium and the endemic equilibrium are first studied. Under the assumption of nonexistence of periodic solution, the global dynamics of the model is established: either the number of infective individuals tends to zero as time evolves or it produces bistability in which there is a region such that the disease will persist if the initial position lies in the region and disappears if the initial position lies outside this region. Computer simulation shows such results.

Nonexistence of periodic solutions and S-asymptotically periodic solutions in fractional difference equations

In this paper, it is shown that a fractional difference equation with a periodic right-hand side can not possess a periodic solution but it can have an S-asymptotically periodic solution. Sufficient conditions are proved for the existence of a unique S-asymptotically periodic solution. An example is also given illustrating the obtained results.

The periodic solution problem of a relative rotation nonlinear system with nonlinear elastic force and generalized damping force

The periodic solution problem of a relative rotation nonlinear system is considered. Firstly, the relative rotation nonlinear dynamic system is established, which contains nonlinear elastic force, commonly damped force and forcing periodic force. Secondly, the result about the nonexistence of periodic solution of the corresponding autonomous system is obtained, and some results about the existence of periodic solutions of the system are obtained by using the continuation theorem of coincidence degree theory. The significance is that we generalize the existing results of the literature. Finally an example is given to illustrate that our results are right.

Periodic Solutions for a Prescribed Mean Curvature Equation with Multiple Delays

We study the existence of periodic solutions for the one-dimensional prescribed mean curvature delay equation(d/dt)(x'(t)/1+x't2) +∑i=1naitgxt-τit=pt. By using Mawhin's continuation theorem, a new result is obtained. Furthermore, the nonexistence of periodic solution for the equation is investigated as well.

Global dynamics of a modified Leslie-Gower predator-prey model with Crowley-Martin functional responses

In this paper, we study a modified Leslie-Gower predator-prey model with Crowley-Martin functional responses. We show the existence of a bounded positive invariant and attracting set. The possibility of existence and uniqueness of positive equilibrium are considered. The asymptotic behavior of the positive equilibrium and the existence of Hopf-bifurcation of nonconstant periodic solutions surrounding the interior equilibrium are considered. The existence and non-existence of periodic solutions are established under suitable conditions. The permanence conditions are also established. We obtained sufficient conditions to ensure the global stability of the unique positive equilibrium, by using suitable Lyapunov functions, LaSalle invariance principle and Dulac’s criterion. We obtained also sufficient conditions for the global stability of the prey-extinction equilibrium when the unique positive equilibrium is not feasible. Finally, numerical simulations are presented to illustrate the analytical results.

Nonexistence of periodic solutions and asymptotically periodic solutions for fractional differential equations

Using the final value theorem of Laplace transform, it is firstly shown that nonhomogeneous fractional Cauchy problem does not have nonzero periodic solution. Secondly, two basic existence and uniqueness results for asymptotically periodic solution of semilinear fractional Cauchy problem in an asymptotically periodic functions space. Furthermore, existence and uniqueness results are extended to a closed, nonempty and convex set which is a subset of a Fréchet space. Some examples are given to illustrate the results.

Diversities of periodic solutions for a class of ecological model

We consider a nonautonomous predator-prey model with nonmonotonic functional response in the periodic environment. Some new sufficient conditions are obtained for the nonexistence of periodic solutions and the global existence of at least one or two positive periodic solutions. Our method is based on Mawhin's coincidence degree and novel estimation techniques for the priori bounds of unknown solutions. Some novel estimation techniques are employed for the priori bounds of unknown solutions to Lz = λNz, which are much different from the arguments used in the previous literature. Some applications are also presented to illustrate the feasibility and effectiveness of our main results. A conclusion ends this article.

Non-existence of periodic solutions in fractional-order dynamical systems and a remarkable difference between integer and fractional-order derivatives of periodic functions

Using the Mellin transform approach, it is shown that, in contrast with integer-order derivatives, the fractional-order derivative of a periodic function cannot be a function with the same period. The three most widely used definitions of fractional-order derivatives are taken into account, namely, the Caputo, Riemann–Liouville and Grunwald–Letnikov definitions. As a consequence, the non-existence of exact periodic solutions in a wide class of fractional-order dynamical systems is obtained. As an application, it is emphasized that the limit cycle observed in numerical simulations of a simple fractional-order neural network cannot be an exact periodic solution of the system.

Dynamics of transitions in population interactions

A two-species model with transitions between population interactions is studied. Rich dynamics is observed as the number and quality of equilibria change when model parameters and functional responses vary. Existence and stability of equilibria and nonexistence of periodic solutions are established, existence of some bifurcation phenomena are analytically and numerically studied, explicit threshold values are computed to determine the kind of interaction (mutualism, competition, host–parasite) between the species, and several numerical examples are provided to illustrate the main results in this work.

A proof for non existence of periodic solutions in time invariant fractional order systems

The aim of this note is to highlight one of the basic differences between fractional order and integer order systems. It is analytically shown that a time invariant fractional order system contrary to its integer order counterpart cannot generate exactly periodic signals. As a result, a limit cycle cannot be expected in the solution of these systems. Our investigation is based on Caputo’s definition of the fractional order derivative and includes both the commensurate or incommensurate fractional order systems.

Qualitative analysis of a generalized system of saturated enzyme reactions

In this paper, we discuss a generalized system of saturated enzyme reactions. In order to see the tendency of concentrations over a large range, we discuss not only its finite equilibria but also its equilibria at infinity. The case of high degeneracy is dealt with by constructing generalized normal sectors. Furthermore, we calculate coefficients of a normal form of the system at the sole finite equilibrium and prove that a unique limit cycle of small amplitude bifurcates from the equilibrium. The existence of periodic solutions of large amplitude is given by Poincaré–Bendixson theorem. Nonexistence of periodic solutions is investigated by discussing the integral of divergence.

Thresholds for breather solutions of the discrete nonlinear Schrödinger equation with saturable and power nonlinearity

We consider the question of existence of periodic solutions (called breather solutions or discrete solitons) for the Discrete Nonlinear Schrödinger Equation with saturable and power nonlinearity. Theoretical and numerical results are proved concerning the existence and nonexistence of periodic solutions by a variational approach and a fixed point argument. In the variational approach we are restricted to DNLS lattices with Dirichlet boundary conditions. It is proved that there exists parameters (frequency or nonlinearity parameters) for which the corresponding minimizers satisfy explicit upper and lower bounds on the power. The numerical studies performed indicate that these bounds behave as thresholds for the existence of periodic solutions. The fixed point method considers the case of infinite lattices. Through this method, the existence of a threshold is proved in the case of saturable nonlinearity and an explicit theoretical estimate which is independent on the dimension is given. The numerical studies, testing the efficiency of the bounds derived by both methods, demonstrate that these thresholds are quite sharp estimates of a threshold value on the power needed for the the existence of a breather solution. This it justified by the consideration of limiting cases with respect to the size of the nonlinearity parameters and nonlinearity exponents.

Robust Analysis and Synthesis for the Nonexistence of Periodic Solutions in a Class of Nonlinear Systems

This paper considers the nonexistence of periodic solutions in a class of nonlinear uncertain systems. Based on the generalized Kalman---Yakubovich---Popov (GKYP) lemma, linear matrix inequalities (LMIs) characterizations are derived to guarantee the nonexistence of periodic solutions in a certain frequency range. The new LMI conditions do not involve any product of the Lyapunov matrix and the system matrices. Based on the results, a dynamic output feedback controller is designed to ensure the nonexistence of periodic solutions in such systems. A concrete application to the Chua circuit shows the applicability and validity of the proposed approach.