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(1 - 5 of 5)
Feedback control of a continuous-flow stirred tank reactor with competing autocatalators
Title
Feedback control of a continuous-flow stirred tank reactor with competing autocatalators
Creator
Chaivorapoj, W., Birol, I., Cinar, A., Teymour, F.
Date
2003-08-06
Publisher
AMER CHEMICAL SOC
Description
Two types of nonlinear feedback control schemes are introduced and analyzed for their capability of recovering the original state of an...
Show moreTwo types of nonlinear feedback control schemes are introduced and analyzed for their capability of recovering the original state of an isothermal continuous-flow stirred tank reactor with one robust cubic autocatalytic species, perturbed by a temporary disturbance of an invading cubic autocatalytic species in the inflow. The control objectives are to eliminate the invading species from the system and to restore the original state of the host species. The extent of applicability of the control design to different nonrobust invading species is studied, when the controller is tuned for a specific invader. Moreover, a time-delay feature is suggested in one of the control schemes developed to achieve the control objectives in systems with poor detection of invading species.
Endnote format citation for DOI:10.1021/ie020427+
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Agent-based control of autocatalytic replicators in networks of reactors
Title
Agent-based control of autocatalytic replicators in networks of reactors
Creator
Tatara, E., Birol, I., Teymour, F., Cinar, A.
Date
2005-03-15
Publisher
PERGAMON-ELSEVIER SCIENCE LTD
Description
Spatially distributed systems such as reactor networks hosting multiple autocatalytic species demonstrate a rich spectrum of complex behavior....
Show moreSpatially distributed systems such as reactor networks hosting multiple autocatalytic species demonstrate a rich spectrum of complex behavior. From a control systems perspective, spatially distributed systems offer a difficult control challenge because of their distributed nature, nonlinearity, and high order. Furthermore, manipulation of the network states may require simultaneous control actions in different parts of the system and may need transients through several operating regimes to achieve the desired operation. The lack of accurate and computationally efficient model-based techniques for large, spatially distributed systems results in complications in controlling the system, either in disturbance rejection or changing the operational regimes of the system. A hierarchical, agent-based control structure is presented whereby local control objectives may be changed in order to achieve the global control objective. The performance of the control system is demonstrated for several global objectives. The challenge posed is to control the spatial distribution of autocatalytic species in a network of five reactors hosting two species using the interaction flow rates as the manipulated variables. The multi-agent control system is able to effectively explore the parameter space of the network and intelligently manipulate the network flow rates such that the desired spatial distribution of species is achieved.
Endnote format citation for DOI:10.1016/j.compchemeng.2004.09.022
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Static and dynamic behavior of autocatalytic replicators in reactor networks
Title
Static and dynamic behavior of autocatalytic replicators in reactor networks
Creator
Tatara, E., Birol, I., Teymour, F., Cinar, A.
Date
2004-07-07
Publisher
AMER CHEMICAL SOC
Description
The static and dynamic behavior of the autocatalytic reaction R + 2P --> 3P with decay P --> D is studied in networks of coupled continuous...
Show moreThe static and dynamic behavior of the autocatalytic reaction R + 2P --> 3P with decay P --> D is studied in networks of coupled continuous stirred tank reactors (CSTRs). Numerical bifurcation studies of the system are performed, resulting in rich steady-state bifurcation structures with multiple steady states and isolas. The heterogeneity of the networks is influenced by the number of reactors as well as the network topology. It is shown that the number of steady states of the network increases with heterogeneity, thereby allowing those autocatalytic species to exist in the network that would normally not exist in the homogeneous environment of a single CSTR. Spatial patterns of stable steady states are evident in reactor networks. Dynamic simulation studies are performed to illustrate the transition from one stable state configuration to another or from stable steady states to periodic regimes.
Endnote format citation for DOI:10.1021/ie030802d
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Measuring complexity in reactor networks with cubic autocatalytic reactions
Title
Measuring complexity in reactor networks with cubic autocatalytic reactions
Creator
Tatara, E., Birol, I., Cinar, A., Teymour, F.
Date
2005-04-13
Publisher
AMER CHEMICAL SOC
Description
Systems with high steady-state multiplicity and rich dynamic behavior are difficult to investigate using conventional reductionist methods. A...
Show moreSystems with high steady-state multiplicity and rich dynamic behavior are difficult to investigate using conventional reductionist methods. A network of more than five reactors hosting cubic autocatalytic reactions may potentially have more than 101 steady states and many distinct dynamic regimes, all for the same parameter set. This paper discusses how the static complexity of such systems can be measured to give a holistic picture. To achieve this, stochastic simulations were performed to statistically determine the bifurcation structure of the system, and the gathered information is summarized using a measure akin to fractal dimension. With this measure, the growth of static complexity is investigated as a function of the network size.
Endnote format citation for DOI:10.1021/ie049246t
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Batch process monitoring and its application to polymerization systems
Title
Batch process monitoring and its application to polymerization systems
Creator
Undey, C., Ertunc, S., Tatara, E., Teymour, F., Cinar, A.
Date
2004-01
Publisher
WILEY-V C H VERLAG GMBH
Description
Slight changes in raw material properties or operating conditions during critical periods of operation of batch and semi-batch polymerization...
Show moreSlight changes in raw material properties or operating conditions during critical periods of operation of batch and semi-batch polymerization reactors may have a strong influence on reaction mechanism and impact final product quality. Online process monitoring, fault detection, fault diagnosis, and product quality prediction in real-time ensure safe reactor operation and warn operators about excursions from normal operation that may lead to deterioration in product properties. Multivariate statistical process monitoring and quality prediction using multiway principal components analysis and multiway partial least squares have been successful in detecting abnormalities in process operation and product quality. When abnormal process operation is detected, fault diagnosis tools are used to determine the source cause of the deviation. Illustrative case studies are presented via simulated polyvinyl acetate polymerization.
Endnote format citation for DOI:10.1002/masy.200450210
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