Global qualitative analysis of new Monod type chemostat model with delayed growth response and pulsed input in polluted environment

In this paper, we consider a new Monod type chemostat model with time delay and impulsive input concentration of the nutrient in a polluted environment. Using the discrete dynamical system determined by the stroboscopic map, we obtain a ＂microorganism-extinction＂ periodic solution. Further, we establish the sufficient conditions for the global attractivity of the microorganism-extinction periodic solution. Using new computational techniques for impulsive and delayed differential equation, we prove that the system is permanent under appropriate conditions. Our results show that time delay is ＂profitless＂.

Confidence domain in the stochastic competition chemostat model with feedback control

This paper studies a stochastically forced chemostat model with feedback control in which two organisms compete for a single growth-limiting substrate. In the deterministic counterpart, previous researches show that the coexistence of two competing organisms may be achieved as a stable positive equilibrium or a stable positive periodic solution by different feedback schedules. In the stochastic case, based on the stochastic sensitivity function technique,we construct the confidence domains for different feedback schedules which allow us to find the configurational arrangements of the stochastic attractors and analyze the dispersion of the random states of the stochastic model.

Spatial Pattern Induced by Cross-Diffusion in a Chemostat Model with Maintenance Energy

A chemostat model with maintenance energy and crossdiffusion is considered,and the formation of patterns is caused by the cross-diffusion. First, through linear stability analysis, the necessary conditions for the formation of the spatial patterns are given. Then numerical simulations by changing the values of crossdiffusions in the unstable domain are performed. The results showthat the cross-diffusion coefficient plays an important role in the formation of the pattern, and the different values of the crossdiffusion coefficients may lead to different types of pattern formation.

On a Hibernation Plankton-Nutrient Chemostat Model with Delayed Response in Growth

In this paper, a hibernation plankton-nutrient chemostat model with delayed response in growth is considered. By using the stroboscopic map and the theorem of impulsive delay differential equation, a plankton-extinction boundary periodic solution is obtained. The sufficient conditions on the permanence and globally attractive of the chemostat system are also obtained. Our main results reveal that the delayed response in growth plays an important role on the dynamical behaviors of system.

Global Analysis of Beddington-DeAngelis Type Chemostat Model with Nutrient Recycling and Impulsive Input

In this paper, a Beddington-DeAngelis type chemostat model with nutrient recycling and impulsive input is considered. Except using Floquet theorem, introducing a new method combining with comparison theorem of impulse differential equation and by using the Liapunov function method, the sufficient and necessary conditions on the permanence and extinction of the microorganism are obtained. Two examples are given in the last section to verify our mathematical results. The numerical analysis shows that if only the system is permanent, then it also is globally attractive.

Dynamics and Hopf Bifurcation Analysis of a Chemostat Model with Modified Growth Rate and Variable Yield Coefficient

The objective of this study is to analyze a chemostat model of very simple type with the Haldane expression of growth rate and a variable yield coefficient. The proposed modified model is analyzed qualitatively and quantitatively. Analytic conditions for stability and optimality are determined for washout and no washout equilibrium solutions. One of the main focuses of the study is to determine parameter values for which Hopf Bifurcations occur in a bioreactor. It has been shown that the maximum stable non-washout equilibrium exits at a residence time under suitable parameter values. Hopf bifurcation is observed at three different conditions of the parameters.

Dynamical Analysis of Nonautonomous Trophic Cascade Chemostat Model with Regime Switching and Nonlinear Perturbations in a Polluted Environment

This paper investigates the stochastic dynamics of trophic cascade chemostat model perturbed by regime switching, Gaussian white noise and impulsive toxicant input. For the system with only white noise interference, sufficient conditions for stochastically ultimate boundedness and stochastically permanence are obtained, and we demonstrate that the stochastic system has at least one nontrivial positive periodic solution. For the system with Markov regime switching, sufficient conditions for extinction of the microorganisms are established. Then we prove the system is ergodic and has a stationary distribution. The results show that both impulsive toxins input and stochastic noise have great effects on the survival and extinction of the microorganisms. Finally, a series of numerical simulations are presented to illustrate the theoretical analysis.

Long-Time Behavior and Density Function of a Stochastic Chemostat Model with Degenerate Diffusion

This paper considers a stochastic chemostat model with degenerate diffusion.Firstly,the Markov semigroup theory is used to establish sufficient criteria for the existence of a unique stable stationary distribution.The authors show that the densities of the distributions of the solutions can converge in L^(1)to an invariant density.Then,conditions are obtained to guarantee the washout of the microorganism.Furthermore,through solving the corresponding Fokker-Planck equation,the authors give the exact expression of density function around the positive equilibrium of deterministic system.Finally,numerical simulations are performed to illustrate the theoretical results.

Stochastic properties of solution for a chemostat model with a distributed delay and random disturbance

In this paper,stochastic properties of solution for a chemostat model with a distributed delay and random disturbance are studied,and we use distribution delay to simulate the delay in nutrient conversion.By the linear chain technique,we transform the stochastic chemostat model with weak kernel into an equivalent degenerate system which contains three equations.First,we state that this model has a unique global positive solution for any initial value,which is helpful to explore its stochastic properties.Furthermore,we prove the stochastic ultimate boundness of the solution of system.Then sufficient conditions for solution of the system tending toward the boundary equilibrium point at exponential rate are established,which means the microorganism will be extinct.Moreover,we also obtain some sufficient conditions for ergodicity of solution of this system by constructing some suitable stochastic Lyapunov functions.Finally,we provide some numerical examples to illustrate theoretical results,and some conclusions and analysis are given.

非均匀Chemostat竞争模型的共存态

本文讨论了一类质粒载体的微生物与质粒自由的微生物竞争的非均匀Chemostat模型.利用极值原理以及Hopf边界引理给出了正平衡解的先验估计,然后利用锥映象不动点指数理论、算子谱分析以及局部分歧理论得到了正平衡解存在的充分条件,最后运用线性算子的扰动理论和分歧解的稳定性理论判定了局部分歧解的稳定性.研究结果表明,当参数满足一定条件时,两竞争物种能够共存.

具有变消耗率的比率确定型chemostat模型渐近行为(英文)

为了使微生物培养的理论研究更接近于实验,建立了一个具有变消耗率的比率确定型chemostat模型.这个模型推广了经典的Monod模型,而且假定了消耗率是一个营养基的线性函数,微生物增长率是比率确定型函数.对该模型作了定性分析,证明了只要正平衡点存在系统就是持续生存的.同时也给出了系统极限环存在和正平衡点全局渐近稳定的充分条件.

一类捕食chemostat模型的食饵一致持续生存(英文)

考虑了一类双营养条件下带时滞的捕食chemostat模型 .利用Liapunov泛函方法和Razu mikhin方法 ,得到了食饵种群一致持续生存 。

一类非均匀搅拌chemostat食物链模型解的性质

目的研究一类非均匀搅拌chemostat食物链模型正平衡解的存在性和稳定性。方法运用极值原理、上下解方法、分歧理论、线性算子的扰动理论和分歧解的稳定性理论进行研究。结果给出了正解存在的充要条件以及证明了共存解的局部稳定性。结论非均匀搅拌的chemostat食物链模型在适当条件下共存解存在并且稳定。

一类带B-D反应项的非均匀Chemostat模型正解的存在性和多解性

本文研究一类带有Beddington-De Angelis反应函数的非均匀Chemostat模型正平衡态解的存在性和多解性.利用分歧理论考察了共存解的全局结构,得到了正平衡态解存在的充分条件.进而讨论了正平衡态解的稳定性和多解性,运用线性算子的扰动理论和不动点指数理论给出了正平衡态的多解条件.结果表明质粒载体微生物的最大生长率对正平衡态解的稳定性和多解性有很大影响.

有代谢功能的Chemostat食物链系统的持久性

讨论了一类Ｃｈｅｍｏｓｔａｔ系统中，单一食饵喂养且具有三个捕食者的食物链模型，当微生物的增长率ｐ（ｓ）为有代谢功能ｐ（０）≠０时 持续生存问题，当系统满足一定条件时，食物链模型是持久．

BIFURCATION AND COMPLEXITY IN A RATIO-DEPENDENT PREDATOR-PREY CHEMOSTAT WITH PULSED INPUT

In this paper, a three dimensional ratio-dependent chemostat model with periodically pulsed input is considered. By using the discrete dynamical system determined by the stroboscopic map and Floquet theorem, an exact periodic solution with positive concentrations of substrate and predator in the absence of prey is obtained. When β is less than some critical value the boundary periodic solution （xs（t）, O, zs（t）） is locally stable, and when β is larger than the critical value there are periodic oscillations in substrate, prey and predator. Increasing the impulsive period T the system undergoes a series of period-doubling bifurcation leading to chaos, which implies that the dynamical behaviors of the periodically pulsed ratio-dependent predator-prey ecosystem are very complex.

一类Chemostat捕食模型正周期解的存在性

讨论了一类Chemostat捕食模型在一定条件下正周期解的存在性问题.运用周期抛物型算子理论、Schauder估计和分歧理论得到了该模型正周期解存在的充分必要条件.

具有脉冲扰动的时滞随机Chemostat模型的全局吸引性(英文)

本文研究了具有混合时滞的随机关脉冲Chemostat模型.混合时滞包括无穷时滞和分布时滞.通过运用M-矩阵理论、微分不等式技巧和随机分析等工具,给出了具有脉冲扰动系统奇点全局吸引的充分条件.同时,给出例子说明本文的方法.

抗生素调节的单种群chemostat模型研究

构建并分构了抗生素调节的单种群chemosta模型 ,得到了依赖于抗生素输入浓度的微生物种群绝灭和一致持续生存的充分条件 .

非均匀Chemostat竞争模型的渐近性

研究了一类非均匀chemostat竞争模型解的渐近性。运用比较原理、极值原理和半动力系统的一致持久性理论进行研究。得到了物种灭绝和持续共存的条件。非均匀chemostat竞争模型在适当条件下物种能持续共存。