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Title: NONLINEAR PREDICTIVE CONTROL OF PERIODICALLY FORCED CHEMICAL REACTORS
Creator: Ozgulsen, F., Kendra, S. J., Cinar, A.
Date: 1993-04
Publisher: AMER INST CHEMICAL ENGINEERS
Description: A nonlinear model-predictive control strategy is developed to maintain the superior-to-steady-state performance of a periodically forced...
Show moreA nonlinear model-predictive control strategy is developed to maintain the superior-to-steady-state performance of a periodically forced chemical reactor. The performance of the predictive con troller is investigated in the presence of measurement disturbances and parametric uncertainty. It is also shown that statistically inferred input-output models can be a substitute whenever detailed fundamental models are not available. A nonlinear autoregressive polynomial model based on observed plant data is built and incorporated into the control scheme. The catalytic oxidation of ethylene in a periodically-forced, continuous stirred-tank reactor is considered as the test case.
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Title: Modeling, monitoring and control strategies for high temperature short time pasteurization systems - 2. Lethality-based control
Creator: Negiz, A., Ramanauskas, P., Cinar, A., Schlesser, J. E., Armstrong, D. J.
Date: 1998-02
Publisher: ELSEVIER SCI LTD
Description: A lethality-based control system was designed to provide accurate control of a high temperature shout time (HTST) pasteurizer and to process...
Show moreA lethality-based control system was designed to provide accurate control of a high temperature shout time (HTST) pasteurizer and to process milk products with a lethality equivalent of 161 degrees F (71.67 degrees C) or above for 15 s. This control system provides significant flexibility in operating the process and optimizing functional properties of the food components. Multivariable control of an HTST pasteurizer is implemented by using product total lethality to determine the controller set-points. The equation that relates the temperature and flow rate combinations to the product total lethality, 161 degrees F (71.67 degrees C), 15 s, was modified to permit overprocessing levels specified by plant personnel. By using this equation and the set-point value selected for the other variable, set-point values for the temperature or the flow rate controller were computed. The flow and temperature controllers are integrated into a real-time monitoring and control system. The monitoring and control system includes the multivariable controller, the lethality rate calculation module, statistical monitoring of the total lethality, product flow rate, hot wafer outlet temperature, and holding tube exit temperature measurements, and the display screens for visual inspection of the monitoring tools. This study attempted to achieve compliance of the HTST process operation with the recommended Pasteurized Milk Ordinance by providing a margin between the alarm limits of the monitoring chart and the safety limits.
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Title: Statistical monitoring of multivariable dynamic processes with state-space models
Creator: Negiz, A., Cinar, A.
Date: 1997-08
Publisher: AMER INST CHEMICAL ENGINEERS
Description: Industrial continuous processes may have a large number of process variables and are usually operated for extended periods at fixed operating...
Show moreIndustrial continuous processes may have a large number of process variables and are usually operated for extended periods at fixed operating points under closed-loop control, yielding process measurements that are autocorrelated, cross-correlated and collinear. A statistical process monitoring (SPM) method based on multivariate statistics and system theory is introduced to monitor the variability of such processes. The statistical model that describes the in-control variability is based on a canonical-variate (CV) stare-space model that is an equivalent representation of a vector autoregressive moving-average rime-series model. The CV state variables obtained from the state-space model are linear combinations of the past process measurements that explain the variability of the future measurements the most. Because of this distinctive feature, the CV state variables are regarded as the principal dynamic directions A T-2 statistic based on the CV state variables is used for developing an SPM procedure. Simple examples based on simulated data and an experimental application based on a high-temperature short-time milk pasteurization process illustrate advantages of the proposed SPM method.
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Title: HACCP with multivariate process monitoring and fault diagnosis techniques: application to a food pasteurization process
Creator: Tokatli, F., Cinar, A., Schlesser, J. E.
Date: 2005-06
Publisher: ELSEVIER SCI LTD
Description: Multivariate statistical process monitoring (SPM), and fault detection and diagnosis (FDD) methods are developed to monitor the critical...
Show moreMultivariate statistical process monitoring (SPM), and fault detection and diagnosis (FDD) methods are developed to monitor the critical control points (CCPs) in a continuous food pasteurization process. Multivariate SPM techniques effectively use information from all process variables to detect abnormal process behavior. Fault diagnosis techniques isolate the source cause of the deviation in process variable(s). The methods developed are illustrated by implementing them to monitor the critical control points and diagnose causes of abnormal operation of a high temperature short time (HTST) pasteurization pilot plant. The detection power of multivariate SPM and FDD techniques over univariate SPM techniques is shown and their integrated use to ensure the product safety and quality in food processes is demonstrated.
Endnote format citation for DOI:10.1016/j.foodcont.2004.04.008
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Title: Controller performance assessment by frequency domain techniques
Creator: Kendra, S. J., Cinar, A.
Date: 1997-06
Publisher: ELSEVIER SCI LTD
Description: A system identification based method for assessing the performance of closed-loop systems is proposed, utilizing measures which coincide...
Show moreA system identification based method for assessing the performance of closed-loop systems is proposed, utilizing measures which coincide naturally with classical and modern frequency domain design specifications. Standard robust control system design methodologies seek to maximize closed-loop performance, subject to strict robustness requirements and include specifications for bandwidth and peak magnitude of the sensitivity and complementary sensitivity functions. Estimates of these transfer functions can be obtained by exciting the reference input with a zero mean, pseudo random binary sequence, observing the process output and error response, and developing a closed-loop model. Performance assessment is based on the comparison between the observed frequency response characteristics and the design specifications. Selection of appropriate model structures, experiment design, and model validation which will ensure reasonable estimates of the closed-loop transfer functions are considered in this paper. A case study involving the performance assessment of a packed bed tubular reactor control system is presented.
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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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Title: Integration of multivariate SPM and FDD by parity space technique for a food pasteurization process
Creator: Kosebalaban, F., Cinar, A.
Date: 2001-03-15
Publisher: PERGAMON-ELSEVIER SCIENCE LTD
Description: Multivariate statistical process monitoring (MSPM), contribution plots, and parity space fault diagnosis (FD) techniques are used to detect...
Show moreMultivariate statistical process monitoring (MSPM), contribution plots, and parity space fault diagnosis (FD) techniques are used to detect abnormal operation of dynamic processes and diagnose sensor and actuator faults. The methods are illustrated by monitoring the critical control points (CCP) and diagnosing causes of abnormal operation of a pilot pasteurization plant. An empirical model of the process is developed by using subspace state space system identification methods and normal process data. The process data collected under the influence of different magnitude and duration of faults in sensors and actuators are used to validate the MSPM and FD techniques. T-2 and squared prediction error (SPEN) charts are used as MSPM charts. A parity space technique for dynamic stochastic systems and dynamic trends in contribution plots of T-2 and SPEN statistics are used for FD. The detection and FD by these techniques show significant improvements over univariate methods.
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Title: Diagnosis of process disturbances by statistical distance and angle measures
Creator: Raich, A., Cinar, A.
Date: 1997
Publisher: PERGAMON-ELSEVIER SCIENCE LTD
Description: Disturbance and fault diagnosis techniques that rely on statistical methods traditionally utilize distance based discrimination functions....
Show moreDisturbance and fault diagnosis techniques that rely on statistical methods traditionally utilize distance based discrimination functions. Complementary information is contained in the angular relations between data clusters representing process operations under various disturbances. A novel disturbance diagnosis approach is presented based on angle discriminants. The diagnosis method is successful in cases where distance based discrimination is not very accurate. The methodology is illustrated by diagnosing various disturbances in the Tennessee Eastman process and compared with the diagnosis utilizing distance based algorithms.
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Title: Intelligent real-time performance monitoring and quality prediction for batch/fed-batch cultivations
Creator: Undey, C., Tatara, E., Cinar, A.
Date: 2004-02-19
Publisher: ELSEVIER SCIENCE BV
Description: Supervision of batch bioprocess operations in real-time during the progress of a batch run offers many advantages over end-of-batch quality...
Show moreSupervision of batch bioprocess operations in real-time during the progress of a batch run offers many advantages over end-of-batch quality control. Multivariate statistical techniques such as multiway partial least squares (MPLS) provide an efficient modeling and supervision framework. A new type of MPLS modeling technique that is especially suitable for online real-time process monitoring and the multivariate monitoring charts are presented. This online process monitoring technique is also extended to include predictions of end-of-batch quality measurements during the progress of a batch run. Process monitoring, quality estimation and fault diagnosis activities are automated and supervised by embedding them into a real-time knowledge-based system (RTKBS). Interpretation of multivariate charts is also automated through a generic rule-base for efficient alarm handling. The integrated RTKBS and the implementation of MPLS-based process monitoring and quality control are illustrated using a fed-batch penicillin production benchmark process simulator.
Endnote format citation for DOI:10.1016/j.jbiotec.2003.10.004
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Title: SYNTHESIS OF MODEL-BASED CONTROLLERS FOR AN AUTOTHERMAL REACTOR
Creator: Chylla, R. W., Cinar, A.
Date: 1990-08
Publisher: CANADIAN SOC CHEMICAL ENGINEERING
Description: Model-based controllers for a bench scale autothermal tubular packed-bed reactor have been formulated using the Internal Model Control (IMC)...
Show moreModel-based controllers for a bench scale autothermal tubular packed-bed reactor have been formulated using the Internal Model Control (IMC) approach. The Structural Dominance Analysis technique has been used in developing the reduced-order models. Controller performance at robust and sensitive steady states have been assessed through simulations and experiments. Both PI and model-based controllers can regulate reactor operation at robust steady states, but only third order IMC controllers are able to regulate reactor operation at the sensitive steady state.
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Title: DYNAMIC ESTIMATION OF TEMPERATURE AND CONCENTRATION PROFILES IN A PACKED-BED REACTOR
Creator: Windes, L. C., Cinar, A., Ray, W. H.
Date: 1989
Publisher: PERGAMON-ELSEVIER SCIENCE LTD
Description: A two-dimensional nonlinear distributed-parameter optimal state estimation algorithm has been developed and applied to an exothermic packed...
Show moreA two-dimensional nonlinear distributed-parameter optimal state estimation algorithm has been developed and applied to an exothermic packed bed catalytic reactor. Temperature and concentration profiles were estimated from limited temperature and/or concentration measurements. Orthogonal collocation was used to solve the differential sensitivity and filtering equations. Both simulations and on-line experiments with a pilot scale packed bed reactor for the partial oxidation of methanol have been used to study the effects of measurement choice, model parameter errors, and unmeasured process disturbances. Excellent tracking of the reactor profiles was achieved with only one or two properly placed temperature sensors.
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Title: A COMPARATIVE-STUDY OF TOOLS FOR ASSESSING THE EFFECTS OF FORCED PERIODIC OPERATION OF CATALYTIC REACTORS
Creator: Ozgulsen, F., Rigopoulos, K. R., Cinar, A.
Date: 1992
Publisher: GORDON BREACH SCI PUBL LTD
Description: Two methods for assessing the effects of forced periodic catalytic reactor operation are presented. The vibrational control method is an...
Show moreTwo methods for assessing the effects of forced periodic catalytic reactor operation are presented. The vibrational control method is an analytical technique which evaluates the effects of high frequency forcing of system parameters by the method of averaging. The second technique is a numerical tool based on a shooting algorithm. These methods are capable of handling multiple input forcing and various shapes of forcing functions. Both methods are applied to isothermal, adiabatic and nonadiabatic operation of an internal recycle reactor in which the catalytic oxidation of ethylene takes place. The basic features of both techniques are discussed and the results obtained by using these methods are compared. Effects of single and multiple input parameter forcing are investigated. Experimental verification of the theoretical results is also performed for the isothermal case.
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Title: VIBRATIONAL STABILIZATION OF A CHEMICAL REACTOR - AN EXPERIMENTAL-STUDY
Creator: Cinar, A., Deng, J., Meerkov, S. M., Shu, X. S.
Date: 1987-04
Publisher: IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
Description: Vibrational control is a method for modification of dynamic properties of linear and nonlinear systems by introduction of fast, zero-average...
Show moreVibrational control is a method for modification of dynamic properties of linear and nonlinear systems by introduction of fast, zero-average oscillations in a system's parameters. It has been previously shown that forced oscillations introduced in the reactant flow rates to a continuous stirred tank reactor (CSTR) cause a modification of theS- shaped steady-state curve. In the present note experimental evidence is given to show that this modification leads to the operation the CSTR at an asymptotically stable periodic regime located near an unstable steady-state of the reactor system having fixed flow rates. For a given average stabilized state, such a stabilizing mechanism results in a higher production rate or lower energy expenditure compared to a steady operation with shifted input conditions.
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Title: FORCED PERIODIC CONTROL OF AN EXOTHERMIC CSTR WITH MULTIPLE INPUT OSCILLATIONS
Creator: Rigopoulos, K., Shu, X. S., Cinar, A.
Date: 1988-12
Publisher: AMER INST CHEMICAL ENGINEERS
Description: Interaction among various oscillating inputs may result in significant modifications in the behavior of a system under forced periodic control...
Show moreInteraction among various oscillating inputs may result in significant modifications in the behavior of a system under forced periodic control. Forced oscillations in the input flow rate and input concentrations of an exothermic continuous stirred tank reactor enable the stabilized operation of the CSTR in the unstable steady state region. Reactor temperature oscillations under forced periodic control are similar to the oscillations resulting from proportional-integral feedback or nonlinear (push-pull) feedback control, and under some operating conditions the oscillation amplitude is significantly lower. Theoretical and experimental studies illustrate the effects of forcing frequency and phase shift on reactor behavior.
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Title: THE BIFURCATION BEHAVIOR OF AN AUTOTHERMAL PACKED-BED TUBULAR REACTOR
Creator: Adomaitis, R. A., Cinar, A.
Date: 1988
Publisher: PERGAMON-ELSEVIER SCIENCE LTD
Description: The analysis of a chemical reactor by numerical bifurcation techniques can completely define the multiplicity and stability of its equilibrium...
Show moreThe analysis of a chemical reactor by numerical bifurcation techniques can completely define the multiplicity and stability of its equilibrium states and can give insights into the reactor's parametric sensitivity and dynamical behavior in the neighborhood of the chosen operating points. In this paper, we will present some of the numerical bifurcation techniques used and developed in analyzing an autothermal packed bed tubular reactor. The bifurcation behavior found will be cataloged over the range of relevant reactant inlet conditions, and an explanation for the isolated solution branches characteristic of this reactor will also be presented.
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Title: A morphologically structured model for penicillin production
Creator: Birol, G., Undey, C., Parulekar, S. J., Cinar, A.
Date: 2002-03-05
Publisher: JOHN WILEY & SONS INC
Description: A morphologically structured model is proposed to describe penicillin production in fed-batch cultivations. The model accounts for the effects...
Show moreA morphologically structured model is proposed to describe penicillin production in fed-batch cultivations. The model accounts for the effects of dissolved oxygen on cell growth and penicillin production and variations in volume fractions of abiotic and biotic phases due to biomass formation. Penicillin production is considered to occur in the subapical hyphal cell compartment and to be affected by availability of glucose and oxygen. As it stands, the model provides a wide range of applicability in terms of operating conditions. The model has been tested for various conditions and has given satisfactory results. A series of glucose feeding profiles have been considered to demonstrate the capabilities of the proposed model. It is concluded that the model may be valuable for the interpretation of experimental data collected specifically for metabolic flux analysis during fed-batch cultivation because the elements of measured specific production rates are determined from measurements of the concentrations of the components and their mass balances. The proposed model may be further used for developing control strategies and model order reduction algorithms
Endnote format citation for DOI:10.1002/bit.10115
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Title: Intelligent process monitoring by interfacing knowledge-based systems and multivariate statistical monitoring
Creator: Norvilas, A., Negiz, A., Decicco, J., Cinar, A.
Date: 2000-08
Publisher: ELSEVIER SCI LTD
Description: An intelligent process monitoring and fault diagnosis environment has been developed by interfacing multivariate statistical process...
Show moreAn intelligent process monitoring and fault diagnosis environment has been developed by interfacing multivariate statistical process monitoring (MSPM) techniques and knowledge-based systems (KBS) for monitoring multivariable process operation. The real-time KBS developed in G2 is used with multivariate SPM methods based on canonical variate stare space (CVSS) process models. Fault detection is based on T-2 charts of state variables. Contribution plots in G2 are used for determining the process variables that have contributed to the out-of-control signal indicated by large T-2 values, and G2 Diagnostic Assistant (GDA) is used to diagnose the source causes of abnormal process behavior. The MSPM modules developed in Matlab are linked with G2. This intelligent monitoring and diagnosis system can be used to monitor multivariable processes with autocorrelated, cross-correlated, and collinear data. The structure of the integrated system is described and its performance is illustrated by simulation studies.
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Title: Statistical process monitoring and disturbance diagnosis in multivariable continuous processes
Creator: Raich, A., Cinar, A.
Date: 1996-04
Publisher: AMER INST CHEMICAL ENGINEERS
Description: Detecting out-of-control status and diagnosing disturbances leading to the abnormal process operation early are crucial in minimizing product...
Show moreDetecting out-of-control status and diagnosing disturbances leading to the abnormal process operation early are crucial in minimizing product quality variations Multivariate statistical techniques are used to develop detection methodology for abnormal process behavior and diagnosis of disturbances causing poor process performance. Principal components and discriminant analysis ave applied to quantitatively describe and interpret step, ramp and random-variation disturbances. All disturbances require high-dimensional models for accurate description and cannot be discriminated by biplots. Diagnosis of simultaneous multiple faults is addressed by building quantitative measures of overlap between models of single faults and their combinations. These measures are used to identify the existence of secondary disturbances and distinguish their components. The methodology is illustrated by monitoring the Tennessee Eastman plant simulation benchmark problem subjected to different disturbances. Most of the disturbances can be diagnosed correctly, the success rate being higher for step and vamp disturbances than random-variation disturbances.
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Title: Fault detection and diagnosis in a food pasteurization process with hidden Markov models
Creator: Tokatli, F., Cinar, A.
Date: 2004-12
Publisher: CANADIAN SOC CHEMICAL ENGINEERING
Description: Hidden Markov Models (HMM) are used to detect abnormal operation of dynamic processes and diagnose sensor and actuator faults. The method is...
Show moreHidden Markov Models (HMM) are used to detect abnormal operation of dynamic processes and diagnose sensor and actuator faults. The method is illustrated by monitoring the operation of a pasteurization plant and diagnosing causes of abnormal operation. Process data collected under the influence of faults of different magnitude and duration in sensors and actuators are used to illustrate the use of HMM in the detection and diagnosis of process faults. Case studies with experimental data from a high-temperature-short-time pasteurization system showed that HMM can diagnose the faults with certain characteristics such as fault duration and magnitude.
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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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