Effect of random movement and cooperative hunting in the prey-predator system:A dynamical approach

Self-diffusion prerequisite is obtained as the spreading approach of biological populations.Cooperative hunting is a common behavior in predator populations that promotes predation and the coexistence of the prey-predator system.On the other side,the Allee effect among prey may cause the system to become unstable.In this paper,a difusive prey predator system with cooperative hunting and the weak Allee effect in prey populations is discussed.The linear stability and Hopf-bifurcation analysis had been used to examine the system's stability.From the spatial stability of the system,the conditions for Turing instability have been derived.The multiple-scale analysis has been used to derive the amplitude equations of the system.The stability analysis of these amplitude equations leads to the formation of Turing patterns.Finally,numerical simulations are used to analyze spatial patterns forming in 1-D and 2-D.The studies indicate that the model can generate a complex pattern structure and that self-diffusion has a drastic impacton species distribution.

Multi-UAV Cooperative Hunting in Cluttered Environments Considering Downwash E®ects

This paper presents a novel solution to the three-dimensional (3D) cooperative hunting ofmultiple drones that deals with surrounding a target simultaneously while navigating aroundobstacles in the cluttered dynamic 3D environment. Meanwhile, drones avoid the air°owdownwash force created by the spinning propellers on unmanned aerial vehicles (UAVs) andtheir e®ect on the other UAVs. This solution consists of a 3D Simultaneous Encirclementstrategy, the cooperative hunting objective with a novel revised particle swarm optimization(PSO*) path planning algorithm, a °ocking theory-inspired obstacle avoidance algorithm, and acascade PI controller. Simulation results with varying conditions were carried out to validatethe e®ectiveness of the proposed solution by successfully taking care of the downwash e®ects,and having multiple hunter UAVs hunt and encircle a moving or stationary target in a dynamicor static obstacle-rich cluttered environment.

Cooperative multi-target hunting by unmanned surface vehicles based on multi-agent reinforcement learning

To solve the problem of multi-target hunting by an unmanned surface vehicle(USV)fleet,a hunting algorithm based on multi-agent reinforcement learning is proposed.Firstly,the hunting environment and kinematic model without boundary constraints are built,and the criteria for successful target capture are given.Then,the cooperative hunting problem of a USV fleet is modeled as a decentralized partially observable Markov decision process(Dec-POMDP),and a distributed partially observable multitarget hunting Proximal Policy Optimization(DPOMH-PPO)algorithm applicable to USVs is proposed.In addition,an observation model,a reward function and the action space applicable to multi-target hunting tasks are designed.To deal with the dynamic change of observational feature dimension input by partially observable systems,a feature embedding block is proposed.By combining the two feature compression methods of column-wise max pooling(CMP)and column-wise average-pooling(CAP),observational feature encoding is established.Finally,the centralized training and decentralized execution framework is adopted to complete the training of hunting strategy.Each USV in the fleet shares the same policy and perform actions independently.Simulation experiments have verified the effectiveness of the DPOMH-PPO algorithm in the test scenarios with different numbers of USVs.Moreover,the advantages of the proposed model are comprehensively analyzed from the aspects of algorithm performance,migration effect in task scenarios and self-organization capability after being damaged,the potential deployment and application of DPOMH-PPO in the real environment is verified.

Cooperative hunting in a discrete predator-prey system

We propose and investigate a discrete-time predator-prey system with cooperative hunting in the predator population.The model is constructed from the classical Nicholson-Bailey host-parasitoid system with density dependent growth rate.A sufficient condition based on the model parameters for which both populations can coexist is derived,namely that the predator’s maximal reproductive number exceeds one.We study existence of interior steady states and their stability in certain parameter regimes.It is shown that the system behaves asymptotically similar to the model with no cooperative hunting if the degree of cooperation is small.Large cooperative hunting,however,may promote persistence of the predator for which the predator would otherwise go extinct if there were no cooperation.

Impact of time delay and cooperation strategy on the stability of a predator-prey model with Holling type III functional response

In this paper,we propose and analyze a delayed predator-prey model with Holling type III functional response taking into account cooperation behavior in predators.The time delay is introduced in the attack rate to represent the time necessary to trigger the attack.Each analytical result is followed by an ecological interpretation.We investigate the effect of hunting cooperation on both the number and the level of positive steady states.We observe that the level of the positive equilibrium decreases when increasing the hunting cooperation parameter.Then,we study the impact of the delay as well as the cooperation in hunting on the dynamics of the system.We prove that the presence of delay in the attack rate induces stability switches around the coexisting equilibrium when predators cooperate.In addition,we consider the discrete delay as a bifurcation parameter and prove that the model undergoes a Hopf-bifurcation at the coexisting equilibrium when the delay crosses some critical values.Numerical simulations are presented to confirm our analytical findings.

Dynamical study of a predator-prey system with Michaelis-Menten type predator-harvesting

The predation process plays a significant role in advancing life evolution and the maintenance of ecological balance and biodiversity.Hunting cooperation in predators is one of the most remarkable features of the predation process,which benefits the predators by developing fear upon their prey.This study investigates the dynamical behavior of a modified LV-type predator-prey system with Michaelis-Menten-type harvesting of predators where predators adopt cooperation strategy during hunting.The ecologically feasible steady states of the system and their asymptotic stabilities are explored.The local codimension one bifurcations,viz.transcritical,saddle-node and Hopf bifurcations,that emerge in the system are investigated.Sotomayors approach is utilized to show the appearance of transcritical bifurcation and saddle-node bifurcation.A backward Hopfbifurcation is detected when the harvesting effort is increased,which destabilizes the system by generating periodic solutions.The stability nature of the Hopf-bifurcating periodic orbits is determined by computing the first Lyapunov coefficient.Our analyses revealed that above a threshold value of the harvesting effort promotes the coexistence of both populations.Similar periodic solutions of the system are also observed when the conversion efficiency rate or the hunting cooperation rate is increased.We have also explored codimension two bifurcations viz.the generalized Hopf and the Bogdanov-Takens bifurcation exhibit by the system.To visualize the dynamical behavior of the system,numerical simulations are conducted using an ecologically plausible parameter set.The existence of the bionomic equilibrium of the model is analyzed.Moreover,an optimal harvesting policy for the proposed model is derived by considering harvesting effort as a control parameter with the help of Pontryagins maximum principle.