scholarly journals Theoretical Study and Optimization of the Biochemical Reaction Process by Means of Feedback Control Strategy

2013 ◽  
Vol 2013 ◽  
pp. 1-13 ◽  
Author(s):  
Kaibiao Sun ◽  
Andrzej Kasperski ◽  
Yuan Tian
Keyword(s):  
Mathematical Model ◽  
Feedback Control ◽  
Theoretical Analysis ◽  
Numerical Simulations ◽  
Control Strategy ◽  
Theoretical Study ◽  
Biomass Productivity ◽  
Reaction Process ◽  
Biochemical Reaction ◽  
Feedback Control Strategy

The aim of this work is to present a theoretical analysis and optimization of a biochemical reaction process by means of feedback control strategy. To begin with, a mathematical model of the biochemical reaction process with feedback control is formulated. Then, based on the formulated model, the analysis of system's dynamics is presented. The optimization of the bioprocess is carried out, in order to achieve maximal biomass productivity. It is shown that during the optimization, the bioprocess with impulse effects loses the possibility of synchronization and strives for a simple continuous bioprocess. The analytical results presented in the work are validated by numerical simulations for the Tessier kinetics model.

scholarly journals Simulation and feedback control of the Ahmed body flow exhibiting symmetry breaking behaviour

2017 ◽  
Vol 817 ◽  
Author(s):  
O. Evstafyeva ◽  
A. S. Morgans ◽  
L. Dalla Longa
Keyword(s):  
Reynolds Number ◽  
Feedback Control ◽  
Symmetry Breaking ◽  
Numerical Simulations ◽  
Control Strategy ◽  
Low Reynolds Number ◽  
Reynolds Numbers ◽  
Low Reynolds ◽  
Feedback Control Strategy ◽  
Ahmed Body

The present work considers the low-Reynolds-number wake flow behind a squareback Ahmed body, in close proximity to a ground. At low Reynolds numbers such wakes are known to undergo a series of bifurcations to a state that breaks reflectional symmetry. The symmetry breaking of the wake also persists at turbulent high Reynolds numbers, where it manifests as bi-modal behaviour with random switching between the asymmetric states. Thus far, it has only been possible to study the low-Reynolds-number sequence of bifurcations experimentally and mathematically. The present work presents the first numerical simulations capturing the sequence of symmetry breaking bifurcations that occur. A study of how the wake topology changes throughout suggests that interaction between the closer top/bottom pair of parallel shear layers can only dominate once there is sufficient underbody flow. When this occurs, the two main vortex structures in the wake switch from being horizontally to vertically aligned. A linear feedback control strategy, designed to attenuate base pressure force fluctuations, is then implemented. This causes an accompanying reduction in drag and re-symmetrisation of the wake. Analysis using the dynamic mode decomposition confirms that the wake shedding mode is re-symmetrised. This work motivates future attempts to capture wake symmetry breaking and bi-modality in numerical simulations, and application of a promising feedback control strategy at higher, turbulent Reynolds numbers.

FEEDBACK CONTROL OF THE CHEMOTHERAPY OF HIV

2000 ◽  
Vol 10 (09) ◽  
pp. 2207-2219 ◽  
Author(s):  
JOSE ALVAREZ-RAMIREZ ◽  
MONICA MERAZ ◽  
JORGE X. VELASCO-HERNANDEZ
Keyword(s):  
Human Immunodeficiency Virus ◽  
Immune System ◽  
Feedback Control ◽  
Numerical Simulations ◽  
Control Strategy ◽  
Early Treatment ◽  
Viral Production ◽  
Hiv Dynamics ◽  
Immunodeficiency Virus ◽  
Feedback Control Strategy

Using a model which describes the interaction of the immune system with the human immunodeficiency virus (HIV), we introduce a feedback control strategy of chemotherapy in an early treatment setting, where the control represents the percentage of effect chemotherapy has on the viral production. We seek to regulate the viral count by manipulating the percentage of effect chemotherapy has on the viral production. We show via numerical simulations that the proposed feedback control strategy can handle strong uncertainties in the HIV dynamics induced by imperfect modeling and sampled/delayed cell measurements.

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

Processes ◽  
2019 ◽  
Vol 7 (10) ◽  
pp. 758 ◽  
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.

Mathematical Model Establishment and Analysis on the Pipe Deformation under External Pressure with the Ovality

2013 ◽  
Vol 760-762 ◽  
pp. 2263-2266
Author(s):  
Kang Yong ◽  
Wei Chen
Keyword(s):  
Mathematical Model ◽  
Theoretical Analysis ◽  
Yield Strength ◽  
Residual Stresses ◽  
Numerical Simulations ◽  
Significant Influence ◽  
External Pressure ◽  
Pipe Diameter ◽  
Axial Loads ◽  
The Stability

Beside the residual stresses and axial loads, other factors of pipe like ovality, moment could also bring a significant influence on pipe deformation under external pressure. The Standard of API-5C3 has discussed the influences of deformation caused by yield strength of pipe, pipe diameter and pipe thickness, but the factor of ovality degree is not included. Experiments and numerical simulations show that with the increasing of pipe ovality degree, the anti-deformation capability under external pressure will become lower, and ovality affecting the stability of pipe shape under external pressure is significant. So it could be a path to find out the mechanics relationship between ovality and pipe deformation under external pressure by the methods of numerical simulations and theoretical analysis.

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