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Title: A MODEL OBJECT BASED SUPERVISORY EXPERT SYSTEM FOR FAULT TOLERANT CHEMICAL REACTOR CONTROL
Creator: Basila, M. R., Stefanek, G., Cinar, A.
Date: 1990-05
Publisher: PERGAMON-ELSEVIER SCIENCE LTD
Description: An expert system for real-time control of chemical processes provides an environment for coordination of process fault diagnosis, assessment...
Show moreAn expert system for real-time control of chemical processes provides an environment for coordination of process fault diagnosis, assessment of process behavior, automated controller retuning and/or reconfiguration and consequently enables fault-tolerant process control. A supervisory expert system with object-based knowledge representation and heuristic (shallow) and model-based (deep) knowledge is presented. The expert system resides on a PC/386 and communicates with the control system developed in the form of control blocks residing on a PC/286. The prototype of the expert system is developed for retuning model-based controllers to improve the behavior of a packed-bed tubular CO oxidation reactor under autothermal operation. MOBECS is a supervisory expert system designed to tailor the process control system for a tubular autothermal reactor in response to process or control system faults, and changes in the process behavior. Specific functions include process fault diagnosis, control system performance monitoring and trouble-shooting, controller tuning and control system restructuring. As this work progresses, we will also address the problems of sensor placement, state estimation and process identification. Because of the high degree of coupling and interaction between process and control system entities, objects are the best knowledge representation for a process control expert system. The class—object structures of MOBECS is divided into three orthogonal trees representing the process and control system hierarchies and the topology of the system. Using this structure, knowledge is divided into general knowledge applicable to any process or control system and knowledge that is domain specific. The general knowledge is stored in the class structures and, together with generalized rules, forms a knowledge base kernel. This permits rapid prototyping of other applications of MOBECS. Properties are defined as high as possible in the class tree structure and inherited downwards. Knowledge specific to the process is stored in the objects at the leaves of the trees. Rules form the reasoning portion of the knowledge base and contain the causal relationships, meta-knowledge and performance monitoring functions. Rules that perform general monitoring and troubleshooting are applied at the class level through pattern matching. Rule sets are linked through context relationships to identify indirect relationships to the inference engine. These relationships are used with the process topology tree to reduce the search space when a fault is detected. The process monitoring and instability detection rules have been tested by simulating the inputs to the expert system. At the present time, experimental validation of the MOBECS prototype is being undertaken. Once the MOBECS prototype has been fully tested, the knowledge base will be extended to incorporate more complex fault diagnosis, state estimation, sensor placement and controller restructuring.
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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: Nonlinear Interactions as Precursors to Mode Jumps in Resonant Acoustics
Creator: Panickar, P., Srinivasan, K., Raman, G.
Date: 2005-09
Publisher: American Inst Physics
Description: This paper examines instability mode switching in various supersonic jet configurations that involve resonant acoustics. Resonant acoustics...
Show moreThis paper examines instability mode switching in various supersonic jet configurations that involve resonant acoustics. Resonant acoustics includes situations where flow instabilities are enhanced by feedback. The pressure spectra in such situations are rich in multiple modes, and mode switching can occur rather unpredictably. Our experiments reveal that mode switching and the number of nonlinear interactions are interconnected and this number increases just prior to a mode switch. We quantified nonlinear interactions by counting the number of such interactions occurring over a threshold level in the nonlinear cross-bicoherence spectrum and confirmed that nonlinear interactions are precursors to mode jumps. Further, this result was found to be independent of the threshold level. Moreover, if more than one instability mode coexisted, the decay of one and the persistence of the other caused a similar increase in nonlinearities. On the other hand, if there was no mode switch, the nonlinearities remained at comparable limits over the entire operating range. The latter part of the work focused on why difference interactions significantly outnumbered sum interactions in the spectra of shock-containing resonant flows. Using linear stability calculations it is shown that most of the difference interactions that occurred had a positive spatial growth rate and were, hence, unstable. In contrast, a majority of the sum interactions lay outside the amplified region which indicated that they tend to decay spatially. (c) 2005 American Institute of Physics.
http://dx.doi.org/10.1063/1.2008995
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Title: Mixer-ejector Wall Pressure and Temperature Measurements Based on Photoluminescence
Creator: Taghavi, R.r., Raman, G., Bencic, Tj
Date: 2002-04
Publisher: American Inst Aeronaut Astronaut
Description: Ejector side-wall pressure distribution is a key indicator of supersonic jet-mixer-ejector performance. When documenting pressure patterns on...
Show moreEjector side-wall pressure distribution is a key indicator of supersonic jet-mixer-ejector performance. When documenting pressure patterns on an ejector wall using pressure-sensitive paint (PSP), one has to consider temperature variations caused by the supersonic jet flow within the ejector because these can cause significant local errors in the PSP results. If the temperature sensitivity of PSP is not corrected for in complex internal supersonic flows, large localized errors could contaminate the results. In the present work, temperature-sensitive paint maps the temperature distribution on the ejector wall and corrects PSP results point-by-point for temperature sensitivity. The experiments were conducted on multijet supersonic mixer-ejector configurations with straight, convergent (6-deg), and divergent (6-deg) side walls. A comparison of corrected and uncorrected PSP readings shows that at M-j = 1.55, the error with respect to true data from static pressure ports can be reduced from 4.98 to 2.84% for the case of a simple ejector with parallel walls. For the complex 6-deg convergent ejector at M-j = 1.39, the error reduces by almost an order of magnitude (from 20.83 to 2.66%). Our results indicate that the use of this correction technique can significantly reduce PSP errors in complex internal supersonic flow situations.
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Title: Empirical modeling of systems with output multiplicities by multivariate additive NARX models
Creator: Decicco, J., Cinar, A.
Date: 2000-06
Publisher: AMER CHEMICAL SOC
Description: Multivariable additive NARX (nonlinear autoregressive with exogenous inputs) modeling of process systems is presented. The model structure is...
Show moreMultivariable additive NARX (nonlinear autoregressive with exogenous inputs) modeling of process systems is presented. The model structure is similar to that of a generalized additive model (GAM) and is estimated with a nonlinear canonical variate analysis (CVA) algorithm called CANALS. The system is modeled by partitioning the data into two groups of variables. The first is a collection of future outputs, and the second is a collection of past input and outputs and future inputs. This approach is similar to linear subspace state-space modeling. An illustrative example of modeling is presented on the basis of a simulated continuous chemical reactor that exhibits multiple steady states in the outputs for a fixed level of the input.
Endnote format citation for DOI:10.1021/ie9906464
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