Embedded control of cell growth using tunable genetic systems

We present an embedded feedback control strategy to control the density of a bacterial population, allowing cells to self-regulate their growth rate so as to reach a desired density at steady state. We consider a static culture condition, where cells are provided with a limited amount of space and nutrients. The control strategy is built using a tunable expression system (TES), which controls the production of a growth inhibitor protein, complemented with a quorum sensing mechanism for the sensing of the population density. We show on a simplified population-level model that the TES endows the control system with additional flexibility by allowing the set-point to be changed online. Finally, we validate the effectiveness of the proposed control strategy by means of realistic in silico experiments conducted in BSim, an agent-based simulator explicitly designed to simulate bacterial populations, and we test the robustness of our design to disturbances and parameters' variations due, for instance, to cell-to-cell variability.

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Dry chip feedrate control using online chip moisture

TAPPI Journal ◽

10.32964/tj17.05.295 ◽

2018 ◽

Vol 17 (05) ◽

pp. 295-305

Author(s):

Wesley Gilbert ◽

Ivan Trush ◽

Bruce Allison ◽

Randy Reimer ◽

Howard Mason

Keyword(s):

Production Rate ◽

Control Strategy ◽

Rate Control ◽

Near Infrared ◽

Dry Mass ◽

The Other ◽

Process Variability ◽

Moisture Sensor ◽

Feedback Control Strategy ◽

And Control

Normal practice in continuous digester operation is to set the production rate through the chip meter speed. This speed is seldom, if ever, adjusted except to change production, and most of the other digester inputs are ratioed to it. The inherent assumption is that constant chip meter speed equates to constant dry mass flow of chips. This is seldom, if ever, true. As a result, the actual production rate, effective alkali (EA)-to-wood and liquor-to-wood ratios may vary substantially from assumed values. This increases process variability and decreases profits. In this report, a new continuous digester production rate control strategy is developed that addresses this shortcoming. A new noncontacting near infrared–based chip moisture sensor is combined with the existing weightometer signal to estimate the actual dry chip mass feedrate entering the digester. The estimated feedrate is then used to implement a novel feedback control strategy that adjusts the chip meter speed to maintain the dry chip feedrate at the target value. The report details the results of applying the new measurements and control strategy to a dual vessel continuous digester.

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Agent‐based models to investigate sound impact on marine animals: bridging the gap between effects on individual behaviour and population level consequences

Oikos ◽

10.1111/oik.08078 ◽

2021 ◽

Author(s):

Lars O. Mortensen ◽

Magda Ewa Chudzinska ◽

Hans Slabbekoorn ◽

Frank Thomsen

Keyword(s):

Population Level ◽

Agent Based Models ◽

Marine Animals ◽

Individual Behaviour ◽

Agent Based

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An Optimal Feedback Control Strategy for Nonlinear, Distributed-Parameter Processes

Processes ◽

10.3390/pr7100758 ◽

2019 ◽

Vol 7 (10) ◽

pp. 758 ◽

Cited By ~ 2

Author(s):

Debaprasad Dutta ◽

Simant Ranjan Upreti

Keyword(s):

Feedback Control ◽

Oil Recovery ◽

Control Strategy ◽

Moving Boundary ◽

State Feedback Control ◽

Optimal Feedback Control ◽

Distributed Parameter ◽

Optimal State ◽

Non Linear ◽

Feedback Control Strategy

In this work, an optimal state feedback control strategy is proposed for non-linear, distributed-parameter processes. For different values of a given parameter susceptible to upsets, the strategy involves off-line computation of a repository of optimal open-loop states and gains needed for the feedback adjustment of control. A gain is determined by minimizing the perturbation of the objective functional about the new optimal state and control corresponding to a process upset. When an upset is encountered in a running process, the repository is utilized to obtain the control adjustment required to steer the process to the new optimal state. The strategy is successfully applied to a highly non-linear, gas-based heavy oil recovery process controlled by the gas temperature with the state depending non-linearly on time and two spatial directions inside a moving boundary, and subject to pressure upsets. The results demonstrate that when the process has a pressure upset, the proposed strategy is able to determine control adjustments with negligible time delays and to navigate the process to the new optimal state.

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A Feedback Control Strategy for Torque-Vectoring of IWM Vehicles

Volume 3: 16th International Conference on Advanced Vehicle Technologies; 11th International Conference on Design Education; 7th Frontiers in Biomedical Devices ◽

10.1115/detc2014-34372 ◽

2014 ◽

Cited By ~ 3

Author(s):

Francesco Braghin ◽

Edoardo Sabbioni ◽

Gabriele Sironi ◽

Michele Vignati

Keyword(s):

Electric Vehicles ◽

Automotive Industry ◽

Control Strategy ◽

Control Logic ◽

Power Train ◽

Vehicle Handling ◽

Torque Vectoring ◽

Feedback Control Strategy ◽

Object Of Study ◽

Yaw Moment

In last decades hybrid and electric vehicles have been one of the main object of study for automotive industry. Among the different layout of the electric power-train, four in-wheel motors appear to be one of the most attractive. This configuration in fact has several advantages in terms of inner room increase and mass distribution. Furthermore the possibility of independently distribute braking and driving torques on the wheels allows to generate a yaw moment able to improve vehicle handling (torque vectoring). In this paper a torque vectoring control strategy for an electric vehicle with four in-wheel motors is presented. The control strategy is constituted of a steady-state contribution to enhance vehicle handling performances and a transient contribution to increase vehicle lateral stability during limit manoeuvres. Performances of the control logic are evaluated by means of numerical simulations of open and closed loop manoeuvres. Robustness to friction coefficient changes is analysed.

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