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Title: VIBRATIONAL CONTROL OF AN EXOTHERMIC REACTION IN A CSTR - THEORY AND EXPERIMENTS
Creator: Cinar, A., Deng, J., Meerkov, S. M., Shu, X. S.
Date: 1987-03
Publisher: AMER INST CHEMICAL ENGINEERS
Description: Vibrational control is a method for modification of dynamic properties of linear and nonlinear systems by introducing fast, zero-average...
Show moreVibrational control is a method for modification of dynamic properties of linear and nonlinear systems by introducing fast, zero-average oscillations in the system's parameters. In this paper, forced oscillations introduced in the input flow rates of an exothermic continuous stirred-tank reactor (CSTR) are shown to result in a modification of the S-shaped steady state curve. This modification leads to a possibility of operating a CSTR at an asymptotically stable period regime located in the vicinity of an unstable steady state of the reactor system with stationary input flow rates. Thus, vibrations of the input flow rates can be viewed as a stabilizing mechanism for exothermic CSTR's.
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Title: “I’d have to vote against you”: Issue Campaigning via Twitter
Creator: Roback, Andrew, Hemphill, Libby
Date: 2012-12-03, 2013
Description: Using tweets posted with #SOPA and #PIPA hashtags and directed at members of Congress, we identify six strategies constituents employ when...
Show moreUsing tweets posted with #SOPA and #PIPA hashtags and directed at members of Congress, we identify six strategies constituents employ when using Twitter to lobby their elected officials. In contrast to earlier research, we found that constituents do use Twitter to try to engage their officials and not just as a “soapbox” to express their opinions.
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Title: Nonlinear time series models for multivariable dynamic processes
Creator: Cinar, A.
Date: 1995-11
Publisher: ELSEVIER SCIENCE BV
Description: Several paradigms are available for developing nonlinear dynamic input-output models of processes. Polynomial models, threshold models, models...
Show moreSeveral paradigms are available for developing nonlinear dynamic input-output models of processes. Polynomial models, threshold models, models based on spline functions, and polynomial models with exponential and trigonometric functions can describe various types of nonlinearities and pathological behavior observed in many physical processes. A unified nonlinear model development framework is not available, and the search of the appropriate nonlinear structure is part of the model development effort. Various artificial neural network structures and nonlinear time series model structures are presented and illustrated by developing a model from data sets generated by a series of example systems. The use of a nonlinear model development paradigm which is not compatible with the types of nonlinearities that exist in the data can have a significant effect on model development effort and model accuracy.
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Title: MATHEMATICAL-MODELS OF COCURRENT SPRAY-DRYING
Creator: Negiz, A., Lagergren, E. S., Cinar, A.
Date: 1995-10
Publisher: AMER CHEMICAL SOC
Description: A steady state mathematical model for a cocurrent spray dryer-is developed. The model includes the mass, momentum, and energy balances for a...
Show moreA steady state mathematical model for a cocurrent spray dryer-is developed. The model includes the mass, momentum, and energy balances for a single drying droplet as well as the total energy and mass balances of the drying medium. A log normal droplet size distribution is assumed to hold at the exit of the twin-fluid atomizer located at the top of the drying chamber. The discretization of this log normal distribution with a certain number of bins yields a system of nonlinear coupled first-order differential equations as a function of the axial distance of the drying chamber. This system of equations is used to compute the axial changes in droplet diameter, density, velocity, moisture, and temperature for the droplets at each representative bin. Furthermore, the distributions of important process parameters such as droplet moisture content, diameter, density, and temperature are also obtainable along the length of the chamber. On the basis of the developed model, a constrained nonlinear optimization problem is solved, where the exit particle moisture content is minimized with respect to the process inputs subjected to a fixed mean particle diameter at the chamber exit. Response surface studies based on empirical models are also performed to illustrate the effectiveness of these techniques in achieving the optimal solution when an a priori model is not available. The structure of empirical models obtained from the model is shown to be in agreement with the structure of the empirical models obtained from the experimental studies.
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Title: NUMERICAL SINGULARITY ANALYSIS
Creator: Adomaitis, R. A., Cinar, A.
Date: 1991
Publisher: PERGAMON-ELSEVIER SCIENCE LTD
Description: A numerical scheme is presented for classifying the different static bifurcation behaviors exhibited by a nonlinear system in its remaining...
Show moreA numerical scheme is presented for classifying the different static bifurcation behaviors exhibited by a nonlinear system in its remaining parameter space. This numerical technique differs from previously published schemes in that the application of singularity theory is done numerically and requires no explicit differentiations of the system in question. It also does not require the reduction of the mathematical model to a scalar equation. The utility of this multivariable scheme will be demonstrated through an application to a seven PDE tubular packed-bed reactor model.
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Title: Control of complex distributed systems with distributed intelligent agents
Creator: Tatara, Eric, Cinar, Ali, Teymour, Fouad
Date: 2007-06
Publisher: ELSEVIER SCI LTD
Description: Control of spatially distributed systems is a challenging problem because of their complex nature, nonlinearity, and generally high order. The...
Show moreControl of spatially distributed systems is a challenging problem because of their complex nature, nonlinearity, and generally high order. The lack of accurate and computationally efficient model-based techniques for large, spatially distributed systems leads to challenges in controlling the system. Agent-based control structures provide a powerful tool to manago distributed systems by utilizing (organizing) local and global information obtained from the system. A hierarchical, agent-based system with local and global controller agents is developed to control networks of interconnected chemical reactors (CSTRs). The global controller agent dynamically updates local controller agent's objectives as the reactor network conditions change. One challenge posed is control of the spatial distribution of autocatalytic species in a network of reactors hosting multiple species. The multi-agent control system is able to intelligently manipulate the network flow rates such that the desired spatial distribution of species is achieved. Furthermore, the robustness and flexibility of the agent-based control system is illustrated through examples of disturbance rejection and scalability with respect to the size of the network.
Endnote format citation for DOI:10.1016/j.jprocont.2006.06.008
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Title: Online batch/fed-batch process performance monitoring, quality prediction, and variable-contribution analysis for diagnosis
Creator: Undey, C., Ertunc, S., Cinar, A.
Date: 2003-10-01
Publisher: AMER CHEMICAL SOC
Description: An integrated online multivariate statistical process monitoring (MSPM), quality prediction, and fault diagnosis framework is developed for...
Show moreAn integrated online multivariate statistical process monitoring (MSPM), quality prediction, and fault diagnosis framework is developed for batch processes. Batch data from I batches, with J process variables measured at K time points generate a three-way array of size I x K x J. Unfolding this three-way array into a two-way matrix of size IK x J by preserving the variable direction is advantageous for developing online MSPM methods because it does not require estimation of future portions of new batches. Two different multiway partial least squares (MPLS) models are developed. The first model (MPLSV) is developed between the data matrix (IK x J) and the local batch time (or an indicator variable) for online MSPM. The second model (MPLSB) is developed between the rearranged data matrix in the batch direction (I x KJ) and the final quality matrix for online prediction of end-of-batch quality. The problem of discontinuity in process variable measurements due to operation switching (or moving to a different phase) that causes problems in alignment and modeling is addressed. Control limits on variable contribution plots are used to improve fault diagnosis capabilities of the MSPM framework. Case studies from a simulated fed-batch penicillin fermentation illustrate the implementation of the methodology.
Endnote format citation for DOI:10.1021/ie0208218
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Title: Estimation of Future Glucose Concentrations with Subject-Specific Recursive Linear Models
Creator: Eren-oruklu, Meriyan, Cinar, Ali, Quinn, Lauretta, Smith, Donald
Date: 2009-04
Publisher: MARY ANN LIEBERT INC
Description: Background: Estimation of future glucose concentrations is a crucial task for diabetes management. Predicted glucose values can be used for...
Show moreBackground: Estimation of future glucose concentrations is a crucial task for diabetes management. Predicted glucose values can be used for early hypoglycemic/hyperglycemic alarms or for adjustment of insulin injections or insulin infusion rates of manual or automated pumps. Continuous glucose monitoring (CGM) technologies provide glucose readings at a high frequency and consequently detailed insight into the subject's glucose variations. The objective of this research is to develop reliable subject-specific glucose prediction models using CGM data. Methods: Two separate patient databases collected under hospitalized (disturbance-free) and normal daily life conditions are used for validation of the proposed glucose prediction algorithm. Both databases consist of glucose concentration data collected at 5-min intervals using a CGM device. Using time-series analysis, low-order linear models are developed from patients' own CGM data. The time-series models are integrated with recursive identification and change detection methods, which enables dynamic adaptation of the model to inter-/intra-subject variability and glycemic disturbances. Prediction performance is evaluated in terms of glucose prediction error and Clarke Error Grid analysis (CG-EGA). Results: Prediction errors are significantly reduced with recursive identification of the models, and predictions are further improved with inclusion of a parameter change detection method. CG-EGA analysis results in accurate readings of 90% or more. Conclusions: Subject-specific glucose prediction strategy has been developed. Including a change detection method to the recursive algorithm improves the prediction accuracy. The proposed modeling algorithm with small number of parameters is a good candidate for installation in portable devices for early hypoglycemic/hyperglycemic alarms and for closing the glucose regulation loop with an insulin pump.
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Title: Learning the Lingo? Gender, Prestige and Linguistic Adaptation in Review Communities
Creator: Hemphill, Libby, Otterbacher, Jahna
Date: 2011-11-19, 2012-02
Publisher: ACM Press
Description: Women and men communicate differently in both face-to- face and computer-mediated environments. We study linguistic patterns considered...
Show moreWomen and men communicate differently in both face-to- face and computer-mediated environments. We study linguistic patterns considered gendered in reviews contributed to the Internet Movie Database. IMDb has been described as a male-majority community, in which females contribute fewer reviews and enjoy less prestige than males. Analyzing reviews posted by prolific males and females, we hypothesize that females adjust their communication styles to be in sync with their male counterparts. We find evidence that while certain characteristics of “female language” persevere over time (e.g., frequent use of pronouns) others (e.g., hedging) decrease with time. Surprisingly, we also find that males often increase their use of “female” features. Our results indicate, that even when they resemble men’s reviews linguistically, women’s reviews still enjoy less prestige and smaller audiences.
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Title: Agent-based control of spatially distributed chemical reactor networks
Creator: Tatara, Eric, North, Michael, Hood, Cindy, Teymour, Fouad, Cinar, Ali
Date: 2005
Publisher: SPRINGER-VERLAG BERLIN
Description: Large-scale spatially distributed systems provide a unique and difficult control challenge because of their nonlinearity, spatialdistribution...
Show moreLarge-scale spatially distributed systems provide a unique and difficult control challenge because of their nonlinearity, spatialdistribution and generally high order. The control structure for these systems tend to be both discrete and distributed as well and contain discrete and continuous elements. A layered control structure interfaced with complex arrays of sensors and actuators provides a flexible supervision and control system that can deal with local and global challenges. An adaptive agent-based control structure is presented whereby local control objectives may be changed in order to achieve the global control objective. Information is shared through a global knowledge environment that promotes the distribution of ideas through reinforcement. The performance of the agent-based control approach is illustrated in a case study where the interaction front between two competing autocatalytic species is moved from one spatial configuration to another. 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.
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Title: Asian American Chicago Network: A Case Study of Facebook Group Use By Immigrant Groups
Creator: Rao, Xi, Hemphill, Libby
Date: 2016, 2016
Publisher: ACM
Description: Through analyzing data from posts and about users, we describe how one particular Facebook group helps immigrants to the U.S. use social media...
Show moreThrough analyzing data from posts and about users, we describe how one particular Facebook group helps immigrants to the U.S. use social media to build a local community. As a preliminary study in intercultural communication through social media, we analyze one case, the Asian American Chicago Network (AACN) Facebook group, and uncover common topics users discuss and relationships between user tenure and various indicators of leadership and interaction. Our small finalized results from this preliminary project suggest that members of AACN likely use it (1) to build a professional network in the U.S.A., and (2) to reinforce and affirm their Asian culture and identities.
Sponsorship: National Science Foundation Award Number 1525662
Rao, X., & Hemphill, L. (2016). Asian American Chicago Network: A Case Study of Facebook Group Use By Immigrant Groups. In Proceedings of the 19th ACM Conference on Computer Supported Cooperative Work and Social Computing Companion (pp. 381–384). New York, NY, USA: ACM. http://doi.org/10.1145/2818052.2869077
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Title: Automated control and monitoring of thermal processing using high temperature, short time pasteurization
Creator: Schlesser, J. E., Armstrong, D. J., Cinar, A., Ramanauskas, P., Negiz, A.
Date: 1997-10
Publisher: AMER DAIRY SCIENCE ASSOC
Description: High temperature, short time pasteurization was used to evaluate a computer-based system for controlling the pasteurization process, acquiring...
Show moreHigh temperature, short time pasteurization was used to evaluate a computer-based system for controlling the pasteurization process, acquiring data, and monitoring records. Software was used for the control of hot water temperature, flow rate through the centrifugal timing pump, and diversion of under-processed product. Three types of control strategies were conducted: single loop, cascade, and multivariable. The single loop control strategy showed the most rapid responses to temperature changes, but the temperature response curve was slowest to return to its set point. The cascade control strategy showed slower recoveries to temperature changes, but the temperature response curve was smoother. The multivariable control strategy responded slightly faster than the cascade control strategy, and the temperature response curve was slightly smoother than the cascade control strategy. The multivariable control strategy was able to control the flow diversion valve by the use of a lethality controller. The data acquisition system, used to monitor the data obtained from the high temperature, short-time pasteurization system, was within +/- 0.1 degrees C of the temperature recorded by the safety thermal limit recorder. Reliability was determined by examining the changes in the position of the flow diversion valve to identify process deviations and by comparing the changes to the event marker on circular charts. The data acquisition system was an effective alternative for monitoring the completeness of data.
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Title: Gerry-meandering: An Assessment of the Congressional District Model of Depository Allocation (preprint): AhrensGriffinedrev1a
Creator: Ahrens, Aric G., Griffin, Luke A.
Date: 2003-06
Description: The preprint of a published article dealing with the effect of allocating Federal Depositories by Congressional district. Conclusions drawn...
Show moreThe preprint of a published article dealing with the effect of allocating Federal Depositories by Congressional district. Conclusions drawn include the fact that due to redistricting that occurs after each decennial census, over time some districts may have within their boundaries a greater number than the two depositories that Congressional district allocation was intended to produce. Likewise, over time shifting boundaries of districts have created districts that have no depositories whatsoever.
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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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Title: Challenge to the Pollution Haven Hypothesis: A Study of Northeast Asia and China
Creator: Shapiro, Matthew A.
Date: 2013, 2013
Description: This paper explores the phenomena of environmental coordination within Northeast Asia. I initially frame the discussion around claims that...
Show moreThis paper explores the phenomena of environmental coordination within Northeast Asia. I initially frame the discussion around claims that China is a pollution haven for its neighboring countries, and I look for evidence in the domestic and regional environmental institutions which challenge China’s pollution haven status. I find that that there is a science and technology-based epistemic community in Northeast Asia which provides an important theoretical response to counter the pollution haven hypothesis. As well, given its strong science and technological output, Japan is poised to assume leadership of the Northeast Asian environmental regime for at least the short- to medium-term.
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Title: Cavity Resonance Suppression Using Miniature Fluidic Oscillators
Creator: Raman, G., Raghu, S.
Date: 2004-12
Publisher: American Inst Aeronaut Astronaut

Title: Development of High Bandwidth Powered Resonance Tube Actuators with Feedback Control
Creator: Raman, G., Khanafseh, S., Cain, A. B., Kerschen, E.
Date: 2004-01-22
Publisher: Academic Press Ltd Elsevier Science Ltd
Description: A high bandwidth powered resonance tube (PRT) actuator potentially useful for noise and flow control applications was developed. High...
Show moreA high bandwidth powered resonance tube (PRT) actuator potentially useful for noise and flow control applications was developed. High bandwidth allows use of the same actuator at various locations on an aircraft and over a range of flight speeds. The actuator selected for bandwidth enhancement was the PRT actuator, which is an adaptation of the Hartmann whistle. The device is capable of producing high-frequency and high-amplitude pressure and velocity perturbations for active flow control applications. Our detailed experiments aimed at understanding the PRT phenomenon are complemented by an improved analytical model and direct numerical simulations. We provide a detailed characterization of the unsteady pressures in the nearfield of the actuator using phase averaged pressure measurements. The measurements revealed that propagating fluctuations at 9 kHz were biased towards the upstream direction (relative to the supply jet). A complementary computational study validated by our experiments was useful in simulating the details in the region between the supply jet and the resonance tube where it was difficult to gather experimental data. High bandwidth was obtained by varying the depth of the resonance tube that determines the frequency produced by the device. Our actuator could produce frequencies ranging from 1600 to 15,000 Hz at amplitudes as high as 160 dB near the source. The frequency variation with depth is predicted well by the quarter wavelength formula for deep tubes but the formula becomes increasingly inaccurate as the tube depth is decreased. An improved analytical model was developed, in which the compliance and mass of the fluid in the integration slot is incorporated into the prediction of resonance frequencies of the system. Finally a feedback controller that varied both the resonance tube depth and spacing to converge on a desired frequency was developed and demonstrated. We are optimistic that numerous potential applications exist for such high bandwidth high dynamic range actuators. (C) 2003 Published by Elsevier Science Ltd.
http://dx.doi.org/10.1016/S0022-460X(03)00212-8
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Title: Aeroacoustic Features of Coupled Twin Jets with Spanwise Oblique Shock-Cells
Creator: Panickar, P., Srinivasan, K., Raman, G.
Date: 2004-11-22
Publisher: Academic Press Ltd Elsevier Science Ltd
Description: This paper experimentally investigates the aeroacoustics of coupled twin jets of complex geometry. The study was motivated by the fact that...
Show moreThis paper experimentally investigates the aeroacoustics of coupled twin jets of complex geometry. The study was motivated by the fact that twin jet configurations that are commonly used in aircraft propulsion systems can undergo unpredictable resonant coupling resulting in structural damage. Further, nozzles with spanwise oblique exits are increasingly being considered for their aerodynamic and acoustic advantages, as well as stealth benefits. Although several studies have examined aspects of twin jet coupling, very little data is available on the coupling of jets from nozzles of complex geometry. Our study focuses on twin convergent nozzles with an aspect ratio of 7 with spanwise oblique exits operated over the fully expanded Mach number range from 1.3 to 1.6. The inter-nozzle spacing (s/h) was varied from 7.4 to 13.5. However, the focus remained on the lower spacing that is more representative of aircraft applications. Several interesting results have emerged from this study: (1) Coupling of twin nozzles with a beveled exit was observed only when the beveled edges faced each other and the nozzles formed a 'V' shape in the inter-nozzle region. Specifically, if the two beveled edges were oriented away from each other to form an arrowhead (W) shape no coupling was observed. (2) Despite the presence of spanwise antisymmetric, spanwise symmetric and spanwise oblique modes for the single nozzles, only the first two modes were evident in the coupling. (3) The symmetric coupling produced unsteady pressures in the inter-nozzle region that were up to 7.5 dB higher than the antisymmetrically coupled case. (4) Dynamic tests conducted by moving the nozzles apart while they were operating or by continuously changing the stagnation pressure at fixed inter-nozzle spacing revealed that coupling modes could co-exist at non-harmonically related frequencies. These dynamic tests reproduced the static test data. (5) The frequency of both coupling modes agrees with the higher order waveguide modes based on Tam's theory. (6) Differences in broadband shock noise between the 'V' and 'A' configurations were also documented. Our results provide an understanding of complex twin jet coupling and will serve as benchmark data for validating computational models. (C) 2003 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.jsv.2003.10.011
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Title: Using Controlled Unsteady Fluid Mass Addition to Enhance Jet Mixing
Creator: Raman, G.
Date: 1997-04
Publisher: American Inst Aeronaut Astronaut
Description: A rectangular jet was excited by controlled unsteady fluid mass addition using two miniature fluidic jets placed on either side of its narrow...
Show moreA rectangular jet was excited by controlled unsteady fluid mass addition using two miniature fluidic jets placed on either side of its narrow dimension. The subharmonic of the primary's preferred jet column frequency [St(D-e) = fD(e)/U-J = 0.15] was forced in the antisymmetric mode because such forcing persists for longer downstream distances than the fundamental. Details of the phase-averaged flowfield, velocity gradient terms, velocity spectra, and the mean and fluctuating flowfields were documented. The fluidically excited mode grew and persisted in the flow beyond the potential core region. Unsteady fluid mass addition of 12% (4% momentum addition) per fluidic jet resulted in a 35% reduction of the potential core length and about a 60% increase in the normalized mass flux (percentages are with reference to the primary unforced jet). On the basis of the results, it appears that fluidic devices have the potential for use in shear flow control applications.
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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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