Nikhil Pal

Dynamic behavior of ion acoustic waves in electron-positron-ion magnetoplasmas with superthermal electrons and positrons

The dynamic behavior of ion acoustic waves in electron-positron-ion magnetoplasmas with superthermal electrons and positrons has been investigated in the framework of perturbed and non-perturbed Kadomtsev-Petviashili (KP) equations. Applying the reductive perturbation technique, we have derived the KP equation in electron-positron-ion magnetoplasma with kappa distributed electrons and positrons. Bifurcations of ion acoustic traveling waves of the KP equation are presented. Using the bifurcation theory of planar dynamical systems, the existence of the solitary wave solutions and the periodic traveling wave solutions has been established. Two exact solutions of these waves have been derived depending on the system parameters. Then, using the Hirotas direct method, we have obtained two-soliton and three-soliton solutions of the KP equation. The effect of the spectral index κ on propagations of the two-soliton and the three-soliton has been shown. Considering an external periodic perturbation, we have presen...

Stability and Bifurcation Analysis of a Three-Species Food Chain Model with Fear

In the present paper, we investigate the impact of fear in a tri-trophic food chain model. We propose a three-species food chain model, where the growth rate of middle predator is reduced due to the cost of fear of top predator, and the growth rate of prey is suppressed due to the cost of fear of middle predator. Mathematical properties such as equilibrium analysis, stability analysis, bifurcation analysis and persistence have been investigated. We also describe the global stability analysis of the equilibrium points. Our numerical simulations reveal that cost of fear in basal prey may exhibit bistability by producing unstable limit cycles, however, fear in middle predator can replace unstable limit cycles by a stable limit cycle or a stable interior equilibrium. We observe that fear can stabilize the system from chaos to stable focus through the period-halving phenomenon. We conclude that chaotic dynamics can be controlled by the fear factors. We apply basic tools of nonlinear dynamics such as Poincare s...

Chaos control via feeding switching in an omnivory system.

Tanabe and Namba (Ecology, 86, 3411-3414) studied a three species Lotka-Volterra model with omnivory and explored that omnivory can create chaos. It is well documented that predator switching is a similar biological phenomenon to omnivory and likely to occur simultaneously. In the present paper, the tri-trophic Lotka-Volterra food web model with omnivory and predator switching is re-investigated. We observe that if we incorporate predator switching in the system and the intensity of predator switching increases above a threshold value, then the system will be stable from chaotic dynamics. To study the global dynamics of the system extensive numerical simulations are performed. Our analytical and numerical results suggest that predator switching mechanism enhances the stability and the persistence of a food chain system.

Effect of dust ion collisional frequency on transition of dust ion acoustic waves from quasiperiodic motion to limit cycle oscillation in a magnetized dusty plasma

The effect of dust ion collisional frequency on dust ion acoustic waves (DIAWs) is investigated in a magnetized collisional dusty plasma with isothermal electrons considering an external periodic perturbation. Employing the reductive perturbation technique, the damped Kadomtsev-Petviashili equation is derived to describe the dynamic oscillations of DIAWs in the presence of collisions between dusts and ions. It is perceived that the dust ion collisional frequency significantly changes the dynamics of the DIAWs and plays a crucial role in the transition from quasiperiodic motion to limit cycle oscillation. This study may be helpful to understand the effect of dust ion collisional frequency on the features of DIAWs in planetary rings, interstellar clouds, and comet tails.

Chaos Control in a Two Prey and One Predator System with Predator Switching

Vance (Am. Nat. 112:797–813, 1978) modeled a food web consisting of two prey and one predator with competing prey species. Gilpin (Am. Nat. 113:306–308, 1979) explored that for biological feasible parameter values, Vance’s model can produce chaotic dynamics. In the present paper, we consider a modification of Vance’s model by incorporating predator switching into the model for the same set of parameter values considered by Gilpin. We observe that if we increase switching intensity above a threshold value, then the system becomes stable from chaotic oscillations and enhances the persistence of the system.