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(1 - 20 of 137)
Pages
- Title
- JET MIXING CONTROL USING EXCITATION FROM MINIATURE OSCILLATING JETS
- Creator
- Raman, G, Cornelius, D
- Date
- 1995-02
- Publisher
- AMER INST AERONAUT ASTRONAUT
- Title
- PSECMAC Intelligent Insulin Schedule for Diabetic Blood Glucose Management Under Nonmeal Announcement
- Creator
- Teddy, S. D., Quek, C., Lai, E. M.-k., Cinar, A.
- Date
- 2010-03
- Publisher
- IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
- Description
-
Therapeutically, the closed-loop blood glucose-insulin regulation paradigm via a controllable insulin pump offers a potential solution to the...
Show moreTherapeutically, the closed-loop blood glucose-insulin regulation paradigm via a controllable insulin pump offers a potential solution to the management of diabetes. However, the development of such a closed-loop regulatory system to date has been hampered by two main issues: 1) the limited knowledge on the complex human physiological process of glucose-insulin metabolism that prevents a precise modeling of the biological blood glucose control loop; and 2) the vast metabolic biodiversity of the diabetic population due to varying exogneous and endogenous disturbances such as food intake, exercise, stress, and hormonal factors, etc. In addition, current attempts of closed-loop glucose regulatory techniques generally require some form of prior meal announcement and this constitutes a severe limitation to the applicability of such systems. In this paper, we present a novel intelligent insulin schedule based on the pseudo self-evolving cerebellar model articulation controller (PSECMAC) associative learning memory model that emulates the healthy human insulin response to food ingestion. The proposed PSECMAC intelligent insulin schedule requires no prior meal announcement and delivers the necessary insulin dosage based only on the observed blood glucose fluctuations. Using a simulated healthy subject, the proposed PSECMAC insulin schedule is demonstrated to be able to accurately capture the complex human glucose-insulin dynamics and robustly addresses the intraperson metabolic variability. Subsequently, the PSECMAC intelligent insulin schedule is employed on a group of type-1 diabetic patients to regulate their impaired blood glucose levels. Preliminary simulation results are highly encouraging. The work reported in this paper represents a major paradigm shift in the management of diabetes where patient compliance is poor and the need for prior meal announcement under current treatment regimes poses a significant challenge to an active lifestyle.
Endnote format citation for DOI:10.1109/TNN.2009.2036726
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- Title
- Screech Tones from Rectangular Jets with Spanwise Oblique Shock-cell Structures
- Creator
- Raman, G.
- Date
- 1997-01-10
- Publisher
- Cambridge Univ Press
- Description
-
Understanding screech is especially important for the design of advanced aircraft because screech can cause sonic fatigue failure of aircraft...
Show moreUnderstanding screech is especially important for the design of advanced aircraft because screech can cause sonic fatigue failure of aircraft structures. Although the connection between shock-cell spacing and screech frequency is well understood, the relation between non-uniformities in the shock-cell structures and the resulting amplitude, mode, and steadiness of screech have remained unexplored. This paper addresses the above issues by intentionally producing spanwise (larger nozzle dimension) variations in the shock-cell structures and studying the resulting spanwise screech mode. The spanwise-oblique shock-cell structures were produced using imperfectly expanded convergent-divergent rectangular nozzles (aspect ratio = 5) with non-uniform exit geometries. Three geometries were studied: (a) a nozzle with a spanwise uniform edge, (b) a nozzle with a spanwise oblique (single-bevelled) edge, and (c) a nozzle that had two spanwise oblique (double-bevelled) cuts to form an arrowhead-shaped nozzle. For all nozzles considered, the screech mode was antisymmetric in the transverse (smaller nozzle dimension) direction allowing focus on changes in the spanwise direction. Three types of spanwise modes were observed: symmetric (I), antisymmetric (II), and oblique (III), The following significant results emerged: (i) for all cases the screech mode corresponds with the spanwise shock-cell structure, (ii) when multiple screech modes are present, the technique presented here makes it possible to distinguish between coexisting and mutually exclusive modes, (iii) the strength of shocks 3 and 4 influences the screech source amplitude and determines whether screech is unsteady. The results presented here offer hope for a better understanding of screech and for tailoring shock-containing jets to minimize fatigue failure of aircraft components.
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- Title
- VIBRATIONAL CONTROL OF AN EXOTHERMIC CSTR - PRODUCTIVITY IMPROVEMENT BY MULTIPLE INPUT OSCILLATIONS
- Creator
- Shu, X. S., Rigopoulos, K., Cinar, A.
- Date
- 1989-02
- Publisher
- IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
- Description
-
A. Cinar et al. (1987) have shown that vibrational control of an exothermic continuous stirred tank reactor (CSTR) by vibrating the total flow...
Show moreA. Cinar et al. (1987) have shown that vibrational control of an exothermic continuous stirred tank reactor (CSTR) by vibrating the total flow rate modifies its behavior and leads to stabilized operation in its unstable steady-state region. Here, the effect of multiple vibrating inputs and the contribution of their phase shift are investigated. Theoretical and experimental results indicate productivity improvement and amplitude reduction in reactor temperature swings by vibrating both input flow rate and input concentrations.
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- Title
- Automated control of high temperature short time pasteurization
- Creator
- Negiz, A., Cinar, A., Schlesser, J. E., Ramanauskas, P., Armstrong, D. J., Stroup, W.
- Date
- 1996-12
- Publisher
- ELSEVIER SCI LTD
- Description
-
Cascade and multivariable control of a high temperature shot? time (HTST) pasteurization system were tested and compared with the performance...
Show moreCascade and multivariable control of a high temperature shot? time (HTST) pasteurization system were tested and compared with the performance of single-loop feedback control. Multivariable control was implemented on the basis of computations of product temperatures that yield equivalent lethality at a residence time of 15 s at 161 degrees F in the holding tube. Both cascade and multivariable controllers reduced product temperature fluctuations and overshoot compared to single-loop feedback control. Multivariable control was based on on-line computation of equivalent total lethality and it permitted operation at variable flow rates or at the most desirable temperatures for product quality and functionality. Copyright (C) 1996 Elsevier Science Ltd.
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- Title
- FORCED PERIODIC OPERATION OF TUBULAR REACTORS
- Creator
- Ozgulsen, F., Cinar, A.
- Date
- 1994-10
- Publisher
- PERGAMON-ELSEVIER SCIENCE LTD
- Description
-
Forced periodic operation of tubular reactors can increase conversion and yield if proper operating conditions and forcing policies are...
Show moreForced periodic operation of tubular reactors can increase conversion and yield if proper operating conditions and forcing policies are selected. A numerical approach is proposed for computing the effects of periodic input forcing by a shooting algorithm. Such computational tools permit the assessment of the benefits of forced periodic operation of a specific reactor system and the identification of the ranges of operating conditions where forced periodic operation is beneficial. This information provides valuable insight for planning detailed experimental studies. Determining the influential input variables and bracketing the ranges of the operating conditions for improving reactor performance will reduce significantly the experiments needed for selecting the most favorable reactor operation policies. The application of the numerical algorithm is illustrated by assessing the benefits of forced periodic operation to a CO oxidation reactor model. The results reveal substantial improvement in performance with slow cycling in feed concentration.
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- Title
- Multivariable MPC system performance assessment, monitoring, and diagnosis
- Creator
- Schaffer, J., Cinar, A.
- Date
- 2004-03
- Publisher
- ELSEVIER SCI LTD
- Description
-
This study focuses on performance assessment and monitoring of model predictive control systems. A methodology is proposed to determine a...
Show moreThis study focuses on performance assessment and monitoring of model predictive control systems. A methodology is proposed to determine a benchmark and monitor model predictive control performance on-line. A performance measure based on the ratio of historical and achieved performance is used for monitoring and a ratio of design and achieved performance is used for diagnosis. Performance monitoring and diagnosis of causes for poor performance are integrated. A real-time knowledge-based system is developed to supervise monitoring and diagnosis activities. Case studies with linear and nonlinear models of an evaporator illustrate the methodology and limitations of linearity assumptions.
Endnote format citation for DOI:10.1016/j.jprocont.2003.07.003
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- Title
- Multivariate statistical methods for monitoring continuous processes: Assessment of discrimination power of disturbance models and diagnosis of multiple disturbances
- Creator
- Raich, A. C., Cinar, A.
- Date
- 1995-11
- Publisher
- ELSEVIER SCIENCE BV
- Description
-
A new methodology was reported [1,2] for integrated use of principal components analysis (PCA) and discriminant analysis in order to determine...
Show moreA new methodology was reported [1,2] for integrated use of principal components analysis (PCA) and discriminant analysis in order to determine out-of-control status of a continuous process and to diagnose the source causes for abnormal behavior. Most of the disturbances were identified with good rates of success, with a higher success rate for step or ramp type of disturbances. Quantitative tools that evaluate overlap and similarity between high-dimensional PCA models are proposed in this communication, and their implications on determining the discrimination power of PCA models of processes operating under disturbances are discussed. Diagnosis of several disturbances occurring simultaneously is also investigated. The criterion developed provide upper limits of discrimination power of various single and multiple process disturbances. The techniques developed are illustrated by assessing the process described by the Tennessee Eastman Control Challenge problem [3].
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- Title
- INTELLIGENT PROCESS-CONTROL WITH SUPERVISORY KNOWLEDGE-BASED SYSTEMS
- Creator
- Kendra, S. J., Basila, M. R., Cinar, A.
- Date
- 1994-06
- Description
-
The integration of a supervisory knowledge-based system (KBS) with a multivariable control system is examined to provide robust multivariable...
Show moreThe integration of a supervisory knowledge-based system (KBS) with a multivariable control system is examined to provide robust multivariable control of a chemical reaction process. The supervisory KBS is capable of monitoring the process to detect system faults as well as assessing control system performance. If a control system performance deficiency is detected, the KBS formulates and implements the necessary corrective controller tuning. This adaptive capability reduces the conservatism of the robust control system. The underlying mechanisms are discussed and the re-tuning ability of the KBS is illustrated by using rigorous simulations of a chemical reaction process
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- Title
- Screech Tones of Supersonic Jets from Bevelled Rectangular Nozzles
- Creator
- Tam, Ckw, Shen, H., Raman, G.
- Date
- 1997-07
- Publisher
- American Inst Aeronaut Astronaut
- Description
-
It is known experimentally that an imperfectly expanded rectangular jet from a thin-lip convergent nozzle emits only a single dominant screech...
Show moreIt is known experimentally that an imperfectly expanded rectangular jet from a thin-lip convergent nozzle emits only a single dominant screech tone. The frequency of the screech tone decreases continuously with an increase in jet Mach number. However, for a supersonic jet issued from a bevelled nozzle or a convergent-divergent nozzle with straight side walls, the shock cell structure and the screech frequency pattern are fairly complicated and have not been predicted before. It is shown that the shock cell structures of these jets can be decomposed into waveguide modes of the jet flow. The screech frequencies are related to the higher-order waveguide modes following the weakest link screech tone theory. The measured screech frequencies are found to compare web with the predicted screech frequency curves.
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- Title
- Gerry-meandering: An Assessment of the Congressional District Model of Depository Allocation (preprint): AhrensGriffinedrev2
- 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
- Gerry-meandering: An Assessment of the Congressional District Model of Depository Allocation (preprint)
- 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
- DESIGN OF RESILIENT CONTROLLABLE CHEMICAL PROCESSES - AN AUTOTHERMAL REACTOR CASE-STUDY
- Creator
- Chylla, R. W., Cinar, A.
- Date
- 1990-07
- Publisher
- AMER CHEMICAL SOC
- Description
-
A technique for the analysis of state-space linear systems is applied to the problem of selection of resilient chemical process designs....
Show moreA technique for the analysis of state-space linear systems is applied to the problem of selection of resilient chemical process designs. Structural Dominance Analysis affords the evaluation of many process design and control configurations and assessment of the effects of potential manipulated variables and disturbances. After a brief presentation of the analysis method, a complex multibed tubular autothermal reactor system is examined. Resilient process configurations, ease of control, and effects of various inputs on reactor state variables and outputs are considered, and effective control configurations are selected.
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- 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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- Title
- SUPERSONIC JET MIXING ENHANCEMENT USING IMPINGEMENT TONES FROM OBSTACLES OF VARIOUS GEOMETRIES
- Creator
- Raman, G, Rice, Ej
- Date
- 1995-03
- Publisher
- AMER INST AERONAUT ASTRONAUT
- Description
-
This paper reports the results of an experiment that investigated the effect of impingement tones, generated by obstacles of various...
Show moreThis paper reports the results of an experiment that investigated the effect of impingement tones, generated by obstacles of various geometries, on the spreading of a supersonic jet flow. A rectangular supersonic jet was produced using a convergent-divergent nozzle that was operated near its design point (with shocks minimized). Immersing obstacles in the flow produced an intense impingement tone that then propagated upstream (as feedback) to the jet lip and excited the antisymmetric hydrodynamic mode in the jet, thus setting up a resonant self-sustaining loop. The violent flapping motion of the jet due to excitation of the antisymmetric mode, combined with the unsteady wakes of the obstacles, produced large changes in jet mixing. The experiment controlled the frequency and amplitude of the impingement tone excitation by varying the nozzle-to-obstacle distance and the obstacle immersion. Proper shaping of the obstacles made it possible to reduce the thrust penalty significantly.
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- Title
- Monitoring of multivariable dynamic processes and sensor auditing
- Creator
- Negiz, A., Cinar, A.
- Date
- 1998-10
- Publisher
- ELSEVIER SCI LTD
- Description
-
Industrial continuous processes are usually operated under closed-loop control, yielding process measurements that are autocorrelated, cross...
Show moreIndustrial continuous processes are usually operated under closed-loop control, yielding process measurements that are autocorrelated, cross correlated, and collinear. A statistical process monitoring (SPM) method based on state variables is introduced to monitor such processes. The statistical model that describes the in-control variability is based on a canonical variate (CV) state space model. The CV state variables are linear combinations of the past process measurements which explain the variability of the future measurements the most, and they are regarded as the principal dynamic dimensions. A T-2 statistic based on the CV state variables is utilized for developing the SPM procedure. The CV state variables are also used for monitoring sensor reliability. An experimental application to a high temperature short time (HTST) pasteurization process illustrates the proposed methodology.
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- Title
- AXISYMMETRICAL JET FORCED BY FUNDAMENTAL AND SUBHARMONIC TONES
- Creator
- Raman, G, Rice, Ej
- Date
- 1991-07
- Publisher
- AMER INST AERONAUT ASTRONAUT
- Description
-
A circular jet was excited simultaneously by two harmonically related tones. The results of this excitation on jet behavior are reported for...
Show moreA circular jet was excited simultaneously by two harmonically related tones. The results of this excitation on jet behavior are reported for three pairs of Strouhal numbers [St(D) = f*D/U(j) = 0.2 and 0.4, 0.3 and 0.6, 0.4 and 0.8]. For each case, the initial phase difference between the two tones was varied in steps of 45 deg for one full cycle, and the amplitude of the fundamental and subharmonic tones was varied independently over the range of 0.1-7.0% of the jet exit velocity. Several results of this study agreed with other published findings, such as a critical amplitude or the fundamental being required for subharmonic augmentation and the initial phase difference being critical in determining whether the subharmonic is augmented or suppressed. In addition, the detailed documentation or several aspects of this phenomenon, measured in the same experimental facility in a controlled manner, brought out two important points that had eluded previous researchers. First, at high levels of the fundamental and subharmonic forcing amplitudes, the subharmonic augmentation is independent of the initial phase difference. Second, two-frequency excitation is indeed more effective than single-frequency excitation in jet mixing enhancement. Higher spreading rates seem to go along with higher subharmonic levels.
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- Title
- A modular simulation package for fed-batch fermentation: penicillin production
- Creator
- Birol, G., Undey, C., Cinar, A.
- Date
- 2002-11-15
- Publisher
- PERGAMON-ELSEVIER SCIENCE LTD
- Description
-
Simulation software based on a detailed unstructured model for penicillin production in a fed-batch fermentor has been developed. The model...
Show moreSimulation software based on a detailed unstructured model for penicillin production in a fed-batch fermentor has been developed. The model extends the mechanistic model of Bajpai and Reuss by adding input variables such as pH, temperature, aeration rate, agitation power, and feed flow rate of substrate and introducing the CO2 evolution term. The simulation package was then used for monitoring and fault diagnosis of a typical penicillin fermentation process. The simulator developed may be used for both research and educational purposes and is available at the web site: http://www.chee.iit.edu/ similar to control/software.html.
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- Title
- A NUMERICAL-METHOD FOR DETERMINING OPTIMAL PARAMETER VALUES IN FORCED PERIODIC OPERATION
- Creator
- Ozgulsen, F., Adomaitis, R. A., Cinar, A.
- Date
- 1992-02
- Publisher
- PERGAMON-ELSEVIER SCIENCE LTD
- Description
-
A numerical approach for determining values of forcing parameters which maximize performance of a periodically forced system is described....
Show moreA numerical approach for determining values of forcing parameters which maximize performance of a periodically forced system is described. Periodic solutions of the system equations plus a differential form of the time-average performance measure are computed with a shooting algorithm. A nonlinear programming package is used to solve the optimization problem. The algorithm is applied to ethylene oxidation process, using the model of a continuous stirred-tank reactor (CSTR).
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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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