The Experts below are selected from a list of 234 Experts worldwide ranked by ideXlab platform
Lansun Chen - One of the best experts on this subject based on the ideXlab platform.
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Modeling and Analysis of a Turbidostat Model with Monod-Type Kinetics and State Feedback Control
Advanced Materials Research, 2011Co-Authors: Yuan Tian, Lansun ChenAbstract:In this paper, a Turbidostat model with single species for an inhibitory growth-limiting nutrient is considered. The dilution of the Turbidostat is controlled by a critical cell concentration in the bioreactor. It is shown that the limit system of the proposed model has a coexistence equilibrium which is global asymptotically stable. Moreover, it is shown that the limit system doesn’t exist limit cycle in the first quadrant. In addition, it presents the discussion of the bioprocess optimization.
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Impulsive state feedback control of the microorganism culture in a Turbidostat
Journal of Mathematical Chemistry, 2010Co-Authors: Zhong Zhao, Li Yang, Lansun ChenAbstract:In this paper, a mathematical model with the impulsive state feedback control is proposed for Turbidostat system. The sufficient conditions of existence of order-1 and order-2 periodic solutions are obtained by the existence criteria of periodic solution of a general planar impulsive autonomous system. It is shown that the system either tends to a stable state or has a periodic solution, which depends on the feedback state and the initial concentration of microorganism and substrate. Finally, some discussions and numerical simulations are given.
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Dynamic analysis of a Turbidostat model with the feedback control
Communications in Nonlinear Science and Numerical Simulation, 2010Co-Authors: Zhong Zhao, Tieying Wang, Lansun ChenAbstract:Abstract In this paper, a mathematical model with impulsive state feedback control is proposed for Turbidostat system. The sufficient conditions of existence of positive order one periodic solution are obtained by using the existence criteria of periodic solution of a general planar impulsive autonomous system. It is shown that the system either tends to a stable state or has a periodic solution, which depends on the feedback state, the control parameter of the dilution rate and the initial concentration of microorganism and substrate. By investigating the periodic solution, the period and the initial point of the periodic solution are given. The results show that Turbidostat with impulsive state feedback control tends to an order one periodic solution.
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Qualitative analysis of a variable yield Turbidostat model with impulsive state feedback control
Journal of Applied Mathematics and Computing, 2009Co-Authors: Hongjian Guo, Lansun ChenAbstract:A Turbidostat is an apparatus with feedback control system used to continuously culturing microorganisms. The dilution rate of the Turbidostat can be regulated by the control system when the concentration of microorganism, detected by photoelectricity system or other devices, reaches a preset value. Based on the design ideas of the Turbidostat, a differential equation with impulsive state feedback control is proposed for a kind of Turbidostat system in this paper. By the existence criteria of periodic solution of a general planar impulsive autonomous system, the conditions for the existence of periodic solution of order one are obtained according to the preset value and the types of the positive equilibrium of the corresponding system without impulsive control. Furthermore, it is pointed out that the system either tends to a stable state or has a periodic solution. Finally, the theoretical results are verified by numerical simulations.
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Periodic solution of a Turbidostat model with impulsive state feedback control
Nonlinear Dynamics, 2009Co-Authors: Lansun ChenAbstract:In this paper, a Turbidostat model with impulsive state feedback control is considered. We obtain sufficient conditions of the global asymptotical stability of the system without impulsive state feedback control. We also obtain that the system with impulsive state feedback control may have order one periodic solution, and the sufficient condition for existence and stability of order one periodic solution is gotten as well. For some special cases, it is shown that in the system an order two periodic solution may exist. Our results show that the control measure is effective and reliable.
Hailing Wang - One of the best experts on this subject based on the ideXlab platform.
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Mean persistence and extinction for a novel stochastic Turbidostat model
Nonlinear Dynamics, 2019Co-Authors: Huili Xiang, Hailing WangAbstract:A novel stochastic Turbidostat model is proposed and investigated in this paper. Firstly, we verify the existence and uniqueness of the positive solution for the model. Secondly, conditions for mean persistent of microorganism are derived, and the results show that population will be persistent if perturbation is small enough. We also derive conditions of extinction for population in this paper. Finally, theoretical results are verified by two examples and numerical simulations.
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Dynamical Analysis of a Stochastic Multispecies Turbidostat Model
Complexity, 2019Co-Authors: Huili Xiang, Hailing WangAbstract:A stochastic Turbidostat system in which the dilution rate is subject to white noise is investigated in this paper. First of all, sufficient conditions of the competitive exclusion among microorganisms are obtained by employing the techniques of stochastic analysis. Furthermore, the results demonstrate that the competition among microorganisms and stochastic disturbance will affect the dynamical behaviors of microorganisms. Finally, the theoretical results obtained in this contribution are illustrated by numerical simulations.
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Dynamic behaviors of a Turbidostat model with Tissiet functional response and discrete delay
Advances in Difference Equations, 2018Co-Authors: Yong Yao, Huili Xiang, Hailing WangAbstract:In this paper, dynamic behaviors of a Turbidostat model with Tissiet functional response, linear variable yield and time delay are investigated. The existence and boundedness of solutions, the local asymptotic stability of its equilibria and the phenomenon of Hopf bifurcation for this system are considered. Using the Liapunov–LaSalle invariance principle, we show that the washout equilibrium is global asymptotic stability for any time delay. Furthermore, based on some knowledge of limit set, we show the necessary and sufficient conditions of permanent of the Turbidostat model. Finally, numerical simulations are offered to support our results.
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Existence and persistence of positive solution for a stochastic Turbidostat model
Advances in Difference Equations, 2017Co-Authors: Huili Xiang, Hailing WangAbstract:A novel stochastic Turbidostat model is investigated in this paper. The stochasticity in the model comes from the maximal growth rate influenced by white noise. Firstly, the existence and uniqueness of the positive solution for the system are demonstrated. Secondly, we analyze the persistence in mean and stochastic persistence of the system, respectively. Sufficient conditions about the extinction of the microorganism are obtained. Finally, numerical simulation results are given to support the theoretical conclusions.
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Bifurcation analysis of a Turbidostat model with distributed delay
Nonlinear Dynamics, 2017Co-Authors: Huili Xiang, Hailing WangAbstract:In this paper, dynamic behaviors of a Turbidostat model with distributed delay are concerned. Hopf bifurcations arise when the value of bifurcation parameter, the time delay of translation for the nutrient, crosses some critical values. Firstly, the type and stability of bifurcating periodic solutions are determined by the normal form theory and the center manifold theorem. Moreover, the destabilization of periodic solutions is also discussed. Finally, numerical simulation results are given to support the theoretical conclusions.
Huili Xiang - One of the best experts on this subject based on the ideXlab platform.
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Mean persistence and extinction for a novel stochastic Turbidostat model
Nonlinear Dynamics, 2019Co-Authors: Huili Xiang, Hailing WangAbstract:A novel stochastic Turbidostat model is proposed and investigated in this paper. Firstly, we verify the existence and uniqueness of the positive solution for the model. Secondly, conditions for mean persistent of microorganism are derived, and the results show that population will be persistent if perturbation is small enough. We also derive conditions of extinction for population in this paper. Finally, theoretical results are verified by two examples and numerical simulations.
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Dynamical Analysis of a Stochastic Multispecies Turbidostat Model
Complexity, 2019Co-Authors: Huili Xiang, Hailing WangAbstract:A stochastic Turbidostat system in which the dilution rate is subject to white noise is investigated in this paper. First of all, sufficient conditions of the competitive exclusion among microorganisms are obtained by employing the techniques of stochastic analysis. Furthermore, the results demonstrate that the competition among microorganisms and stochastic disturbance will affect the dynamical behaviors of microorganisms. Finally, the theoretical results obtained in this contribution are illustrated by numerical simulations.
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Dynamic behaviors of a Turbidostat model with Tissiet functional response and discrete delay
Advances in Difference Equations, 2018Co-Authors: Yong Yao, Huili Xiang, Hailing WangAbstract:In this paper, dynamic behaviors of a Turbidostat model with Tissiet functional response, linear variable yield and time delay are investigated. The existence and boundedness of solutions, the local asymptotic stability of its equilibria and the phenomenon of Hopf bifurcation for this system are considered. Using the Liapunov–LaSalle invariance principle, we show that the washout equilibrium is global asymptotic stability for any time delay. Furthermore, based on some knowledge of limit set, we show the necessary and sufficient conditions of permanent of the Turbidostat model. Finally, numerical simulations are offered to support our results.
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Existence and persistence of positive solution for a stochastic Turbidostat model
Advances in Difference Equations, 2017Co-Authors: Huili Xiang, Hailing WangAbstract:A novel stochastic Turbidostat model is investigated in this paper. The stochasticity in the model comes from the maximal growth rate influenced by white noise. Firstly, the existence and uniqueness of the positive solution for the system are demonstrated. Secondly, we analyze the persistence in mean and stochastic persistence of the system, respectively. Sufficient conditions about the extinction of the microorganism are obtained. Finally, numerical simulation results are given to support the theoretical conclusions.
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Bifurcation analysis of a Turbidostat model with distributed delay
Nonlinear Dynamics, 2017Co-Authors: Huili Xiang, Hailing WangAbstract:In this paper, dynamic behaviors of a Turbidostat model with distributed delay are concerned. Hopf bifurcations arise when the value of bifurcation parameter, the time delay of translation for the nutrient, crosses some critical values. Firstly, the type and stability of bifurcating periodic solutions are determined by the normal form theory and the center manifold theorem. Moreover, the destabilization of periodic solutions is also discussed. Finally, numerical simulation results are given to support the theoretical conclusions.
Eric Klavins - One of the best experts on this subject based on the ideXlab platform.
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Accelerating Evolutionary Hill Climbs in Parallel Turbidostats
2017Co-Authors: Christopher N. Takahashi, Luis Zaman, Eric KlavinsAbstract:Evolution has been used to address many engineering problems. Within the context of metabolic engineering and synthetic biology, directed evolution has natural applications. However, most research concerning optimizing microbial evolution has been focused on library generation and screening, while accelerating evolutionary hill climbs and been largely ignored. Here, we develop a model to explore how population structure can accelerate evolutionary hill climbs. We show that by adjusting the population size, environmental challenge, and meta-population dynamics that the rate of evolution can be accelerated in parallel Turbidostats. Our analyses leads to two surprising results: small populations are favored over conventionally large microbial populations, and propagating modest fitness improvements is favored over propagating mutants with large beneficial mutations. When combined with rational design and other optimization techniques our theory can accelerate strain development for applications such as consolidated bioprocessing, and bioremidation systems.
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A Low Cost, Customizable Turbidostat for Use in Synthetic Circuit Characterization
2015Co-Authors: Christopher N. Takahashi, Aaron W. Miller, Felix Ekness, Maitreya J. Dunham, Eric KlavinsAbstract:Engineered biological circuits are often disturbed by a variety of environmental factors. In batch culture, where the majority of synthetic circuit characterization occurs, environmental conditions vary as the culture matures. Turbidostats are powerful characterization tools that provide static culture environments; however, they are often expensive, especially when purchased in custom configurations, and are difficult to design and construct in a lab. Here, we present a low cost, open source multiplexed Turbidostat that can be manufactured and used with minimal experience in electrical or software engineering. We demonstrate the utility of this system to profile synthetic circuit behavior in S. cerevisiae. We also demonstrate the flexibility of the design by showing that a fluorometer can be easily integrated
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A low cost, customizable Turbidostat for use in synthetic circuit characterization.
ACS synthetic biology, 2014Co-Authors: Christopher N. Takahashi, Aaron W. Miller, Felix Ekness, Maitreya J. Dunham, Eric KlavinsAbstract:Engineered biological circuits are often disturbed by a variety of environmental factors. In batch culture, where the majority of synthetic circuit characterization occurs, environmental conditions vary as the culture matures. Turbidostats are powerful characterization tools that provide static culture environments; however, they are often expensive, especially when purchased in custom configurations, and are difficult to design and construct in a lab. Here, we present a low cost, open source multiplexed Turbidostat that can be manufactured and used with minimal experience in electrical or software engineering. We demonstrate the utility of this system to profile synthetic circuit behavior in S. cerevisiae. We also demonstrate the flexibility of the design by showing that a fluorometer can be easily integrated.
Christopher N. Takahashi - One of the best experts on this subject based on the ideXlab platform.
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Accelerating Evolutionary Hill Climbs in Parallel Turbidostats
2017Co-Authors: Christopher N. Takahashi, Luis Zaman, Eric KlavinsAbstract:Evolution has been used to address many engineering problems. Within the context of metabolic engineering and synthetic biology, directed evolution has natural applications. However, most research concerning optimizing microbial evolution has been focused on library generation and screening, while accelerating evolutionary hill climbs and been largely ignored. Here, we develop a model to explore how population structure can accelerate evolutionary hill climbs. We show that by adjusting the population size, environmental challenge, and meta-population dynamics that the rate of evolution can be accelerated in parallel Turbidostats. Our analyses leads to two surprising results: small populations are favored over conventionally large microbial populations, and propagating modest fitness improvements is favored over propagating mutants with large beneficial mutations. When combined with rational design and other optimization techniques our theory can accelerate strain development for applications such as consolidated bioprocessing, and bioremidation systems.
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A Low Cost, Customizable Turbidostat for Use in Synthetic Circuit Characterization
2015Co-Authors: Christopher N. Takahashi, Aaron W. Miller, Felix Ekness, Maitreya J. Dunham, Eric KlavinsAbstract:Engineered biological circuits are often disturbed by a variety of environmental factors. In batch culture, where the majority of synthetic circuit characterization occurs, environmental conditions vary as the culture matures. Turbidostats are powerful characterization tools that provide static culture environments; however, they are often expensive, especially when purchased in custom configurations, and are difficult to design and construct in a lab. Here, we present a low cost, open source multiplexed Turbidostat that can be manufactured and used with minimal experience in electrical or software engineering. We demonstrate the utility of this system to profile synthetic circuit behavior in S. cerevisiae. We also demonstrate the flexibility of the design by showing that a fluorometer can be easily integrated
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A low cost, customizable Turbidostat for use in synthetic circuit characterization.
ACS synthetic biology, 2014Co-Authors: Christopher N. Takahashi, Aaron W. Miller, Felix Ekness, Maitreya J. Dunham, Eric KlavinsAbstract:Engineered biological circuits are often disturbed by a variety of environmental factors. In batch culture, where the majority of synthetic circuit characterization occurs, environmental conditions vary as the culture matures. Turbidostats are powerful characterization tools that provide static culture environments; however, they are often expensive, especially when purchased in custom configurations, and are difficult to design and construct in a lab. Here, we present a low cost, open source multiplexed Turbidostat that can be manufactured and used with minimal experience in electrical or software engineering. We demonstrate the utility of this system to profile synthetic circuit behavior in S. cerevisiae. We also demonstrate the flexibility of the design by showing that a fluorometer can be easily integrated.
