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- Title
- Modeling, monitoring and control strategies for high temperature short time pasteurization systems - 1. Empirical model development
- Creator
- Negiz, A., Ramanauskas, P., Cinar, A., Schlesser, J. E., Armstrong, D. J.
- Date
- 1998-02
- Publisher
- ELSEVIER SCI LTD
- Description
-
Dynamic models of high temperature short time (HTST) pasteurization systems can be developed by using empirical model development paradigms...
Show moreDynamic models of high temperature short time (HTST) pasteurization systems can be developed by using empirical model development paradigms such as transfer functions and times series models. Properly designed experiments that excite all output variables provide good data that enable the development of accurate dynamic models. These models are used in feedback control and statistical process monitoring system design. The methodology for time series model development for HTST pasteurization processes is illustrated by using data collected from a pilot scale HTST pasteurization system.
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- Title
- Innovative Actuators for Active Flow and Noise Control
- Creator
- Cain, A. B., Raman, G.
- Date
- 2002
- Publisher
- Professional Engineering Publishing Ltd
- Description
-
Active flow control (AFC) has the potential to improve the efficiency of systems that involve both internal and external fluid flow. The...
Show moreActive flow control (AFC) has the potential to improve the efficiency of systems that involve both internal and external fluid flow. The primary driver in AFC is the expectation that the control will result in significant performance benefits at the system level with all trade-offs factored in. Successful application to aircraft systems can produce lighter, stealthier, agile aircraft with increased range, payload and a muffled acoustic signature. The design of an AFC system requires knowledge of flow phenomena and the selection of appropriate actuators, sensors and a control algorithm. The present overview focuses on actuators. Examples of flow and noise control presented here are restricted to open-loop systems. Various aspects of actuator utilization include actuator output characterization, exploiting resonances (plenum, structural or aeroacoustic) to enhance actuator amplitude and the different modes of actuation. A brief description of a high-bandwidth actuator is also provided, followed by a variety of application examples including edgetone suppression, cavity noise suppression, impingement noise suppression and jet mixing enhancement. The review concludes with a description of the successful application of AFC to the exhaust plume from an aircraft engine (JT8D).
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- Title
- STABILITY OF TUBULAR AND AUTOTHERMAL PACKED-BED REACTORS USING PHASE PLANE ANALYSIS
- Creator
- Chylla, R. W., Adomaitis, R. A., Cinar, A.
- Date
- 1987-07
- Publisher
- AMER CHEMICAL SOC
- Description
-
The regions of stability and parametric sensitivity of countercurrent reactor/heat exchangers are determined explicitly in the plane of inlet...
Show moreThe regions of stability and parametric sensitivity of countercurrent reactor/heat exchangers are determined explicitly in the plane of inlet feed temperature-inlet coolant temperature. The concept of phase plane analysis is generalized to include all orders of reaction rate expressions, a broader range of system parameters, and is extended to the case of autothermal reactors. An industrial hydrocarbon oxidation reactor model and an autothermal CO oxidation reactor model have been used to illustrate and to evaluate the analysis method. The approach presented here is appealing since the region of safe inlet temperatures is determined explicitly and the region of safe operation can be optimized with respect to the reactor design parameters.
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- Title
- Adaptive control strategy for regulation of blood glucose levels in patients with type 1 diabetes
- Creator
- Eren-oruklu, Meriyan, Cinar, Ali, Quinn, Lauretta, Smith, Donald
- Date
- 2009-09
- Publisher
- ELSEVIER SCI LTD
- Description
-
Current insulin therapy for patients with type 1 diabetes often results in high variability in blood glucose concentrations and may cause hype...
Show moreCurrent insulin therapy for patients with type 1 diabetes often results in high variability in blood glucose concentrations and may cause hype rglycemic/hypoglycemic episodes. Closing the glucose control loop with a fully automated electro-mechanical pancreas will improve the quality of life for insulin-dependent patients. An adaptive control algorithm is proposed to keep glucose concentrations within normoglycemic range and dynamically respond to glycemic challenges. A model-based control strategy is used to calculate the required insulin infusion rate, while the model parameters are recursively tuned. The algorithm handles delays associated with insulin absorption, time-lag between subcutaneous and blood glucose concentrations, and variations in inter/intra-subject glucose-insulin dynamics. Simulation results for simultaneous meat and physiological disturbances are demonstrated for subcutaneous insulin infusion.
Endnote format citation for DOI:10.1016/j.jprocont.2009.04.004
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- Title
- Supersonic Jet Screech: Half-century from Powell to the Present
- Creator
- Raman, G.
- Date
- 1995-08-19
- Publisher
- Academic Press Ltd
- Description
-
Under certain conditions, shock-containing jets produce an intense tone referred to as screech. Screech was discovered about half a century...
Show moreUnder certain conditions, shock-containing jets produce an intense tone referred to as screech. Screech was discovered about half a century ago by Alan Powell in England. Here I recount developments in supersonic jet screech - from Powell's first observation in 1951 to now. During this period more than 200 papers have been published - many offering only incremental advances. This paper provides a concise screech resource including a historical perspective, a summary of recent developments and a critical assessment of the state of the art. Topics include modulation of instability waves by shocks, shock-cell models and screech frequency prediction models, unsteady shock motions and clues about their role in shock noise generation. also. detailed nearfield measurements and computer simulation methods now available are discussed. However, despite the advances, screech amplitude prediction remains an elusive but increasingly important goal not only due to concerns about sonic fatigue failure of aircraft structures but because knowledge gained by the study of screech can be applied to a variety of resonant flow situations, including jet impingement, cavity resonance, and closed-loop active flow control. (C) 1999 Academic Press.
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- Title
- Resonant interaction of a linear array of supersonic rectangular jets: An experimental study
- Creator
- Raman, G, Taghavi, R
- Date
- 1996-02-25
- Publisher
- CAMBRIDGE UNIV PRESS
- Description
-
This paper examines a supersonic multi-jet interaction problem that we believe is likely to be important for mixing enhancement and noise...
Show moreThis paper examines a supersonic multi-jet interaction problem that we believe is likely to be important for mixing enhancement and noise reduction in supersonic mixer-ejector nozzles. We demonstrate that it is possible to synchronize the screech instability of four rectangular jets by precisely adjusting the inter-jet spacing. Our experimental data agree with a theory that assumes that the phase-locking of adjacent jets occurs through a coupling at the jet lip. Although synchronization does not change the frequency of the screech tone, its amplitude is augmented. The synchronized multi-jets exhibit higher spreading than the unsynchronized jets, with the single jet spreading the least. We compare the near-field noise of the four jets with synchronized screech to the noise of the sum of four jets operated individually. Our noise measurements reveal that the more rapid mixing of the synchronized multi-jets causes the peak jet noise source to move upstream and to radiate noise at larger angles to the flow direction. Based on our results, we have grounds to believe that screech synchronization is advantageous for noise reduction internal to a mixer-ejector nozzle, since the noise can now be suppressed by a shorter acoustically lined ejector.
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- Title
- Modeling, monitoring and control strategies for high temperature short time pasteurization systems - 3. Statistical monitoring of product lethality and process sensor reliability
- Creator
- Negiz, A., Ramanauskas, P., Cinar, A., Schlesser, J. E., Armstrong, D. J.
- Date
- 1998-02
- Publisher
- ELSEVIER SCI LTD
- Description
-
Statistical process monitoring (SPM) is used in food processing industries to improve productivity and product quality. SPM can also provide...
Show moreStatistical process monitoring (SPM) is used in food processing industries to improve productivity and product quality. SPM can also provide information to operators on how close a process is to non-compliance to product safety limits, and carry out periodic checks of sensor accuracy at high frequency. Traditional SPM tools such as Shewhart charts are not appropriate for continuous food processes because of autocorrelation in data. Four alternative SPM techniques are presented and applied to high temperature short time (HTST) dairy pasteurization. The 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. Monitoring of residuals and parameter change detection techniques ave used for monitoring processes with autocorrelated variables. Hotelling's T-2 and residuals of canonical variates techniques are used for monitoring multivariable processes.
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- Title
- INSTABILITY MODES EXCITED BY NATURAL SCREECH TONES IN A SUPERSONIC RECTANGULAR JET
- Creator
- Raman, G, Rice, Ej
- Date
- 1994-12
- Publisher
- AMER INST PHYSICS
- Title
- VIBRATIONAL CONTROL OF CHEMICAL REACTORS - STABILIZATION AND CONVERSION IMPROVEMENT IN AN EXOTHERMIC CSTR
- Creator
- Cinar, A., Rigopoulos, K., Shu, X., Meerkov, S. M.
- Date
- 1987
- Publisher
- GORDON BREACH SCI PUBL LTD
- Description
-
Vibrational control is an open-loop control strategy implemented by fast zero-average oscillations in the input variables of a system. It has...
Show moreVibrational control is an open-loop control strategy implemented by fast zero-average oscillations in the input variables of a system. It has been previously shown that vibrational control of an exothermic reaction in a CSTR, introduced via oscillations in the input flow rate, modifies the dynamic behavior of the reactor and enables its stabilized operation in the unstable steady-state region. In the present paper it is shown that simultaneous vibrations in input flow rate and concentration lead, in addition to a reduction of the amplitude of oscillations in reactor temperature and/or increase in reactant conversion. It is also shown that the phase shift between the vibrations of the two input variables affects the behavior of the system as well as the amplitude, the frequency and the form of forcing functions.
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- Title
- Statistical monitoring of multistage, multiphase batch processes
- Creator
- Undey, C., Cinar, A.
- Date
- 2002-10
- Publisher
- IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
- Description
-
The monitoring of intermediate phases of production is as important as monitoring and control of the final stage. Here a framework is proposed...
Show moreThe monitoring of intermediate phases of production is as important as monitoring and control of the final stage. Here a framework is proposed for monitoring overall process performance at the end of each batch.
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- Title
- An intelligent system for multivariate statistical process monitoring and diagnosis
- Creator
- Tatara, E., Cinar, A.
- Date
- 2002-04
- Publisher
- I S A-THE INSTRUMENTATION SYSTEMS AUTOMATION SOC
- Description
-
A knowledge-based system (KBS) was designed for automated system identification, process monitoring, and diagnosis of sensor faults. The real...
Show moreA knowledge-based system (KBS) was designed for automated system identification, process monitoring, and diagnosis of sensor faults. The real-time KBS consists of a supervisory system using G2 KBS development software linked with external statistical modules for system identification and sensor fault diagnosis. The various statistical techniques were prototyped in MATLAB, converted to ANSI C code, and linked with the G2 Standard Interface. The KBS automatically performs all operations of data collection, identification, monitoring, and sensor fault diagnosis with little or no input from the user. Navigation throughout the KBS is via menu buttons on each user-accessible screen. Selected process variables are displayed on charts showing the history of the variables over a period of time. Multivariate statistical tests and contribution plots are also shown graphically. The KBS was evaluated using simulation studies with a polymerization reactor through a nonlinear dynamic model. Both normal operation conditions as well as conditions of process disturbances were observed to evaluate the KBS performance. Specific user-defined disturbances were added to the simulation, and the KBS correctly diagnosed both process and sensor faults when present.
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- Title
- Real-time batch process supervision by integrated knowledge-based systems and multivariate statistical methods
- Creator
- Undey, C., Tatara, E., Cinar, A.
- Date
- 2003-08
- Publisher
- PERGAMON-ELSEVIER SCIENCE LTD
- Description
-
Real-time supervision of batch operations during the progress of a batch run offers many advantages over end-of-batch quality control. Process...
Show moreReal-time supervision of batch operations during the progress of a batch run offers many advantages over end-of-batch quality control. 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 and fault diagnosis. Multivariate statistical techniques such as multiway partial least squares (MPLS) provide a powerful modeling, monitoring, and supervision framework. Online process monitoring techniques are developed and extended to include predictions of end-of-batch quality measurements during the progress of a batch run. 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.engappai.2003.09.003
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- Title
- Advances in Understanding Supersonic Jet Screech: Review and Perspective
- Creator
- Raman, G.
- Date
- 1998-02
- Publisher
- Pergamon - Elsevier Science Ltd
- Description
-
Screech tones are produced by imperfectly expanded jets under certain conditions. This paper provides an overview of developments in the field...
Show moreScreech tones are produced by imperfectly expanded jets under certain conditions. This paper provides an overview of developments in the field of supersonic jet screech. The overview includes a historical background, summary of recent developments, and a critical assessment of our current understanding of screech. The subject material has been categorized as described in the table of contents given below. (C) 1998 Elsevier Science Ltd.
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- Title
- DYNAMIC BEHAVIOR OF PERIODIC FEEDBACK-CONTROL SYSTEMS
- Creator
- Kendra, S., Cinar, A.
- Date
- 1991
- Publisher
- GORDON BREACH SCI PUBL LTD
- Description
-
Periodic feedback is a control strategy implemented by fast zero-average oscillations in the parameters of the control law. It is well known...
Show morePeriodic feedback is a control strategy implemented by fast zero-average oscillations in the parameters of the control law. It is well known that time invariant feedback control offers no means for zeros relocation. Periodic feedback allows zeros relocation in an asymptotic sense, resulting in improved closed loop characteristics, such as increased gain margins.
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- Title
- Coupling of Twin Supersonic Jets of Complex Geometry
- Creator
- Raman, G.
- Date
- 1999-10
- Publisher
- American Inst Aeronaut Astronaut
- Description
-
Fundamental issues about the coupling of twin supersonic jets of complex geometry are examined. It is shown that screech tones from twin...
Show moreFundamental issues about the coupling of twin supersonic jets of complex geometry are examined. It is shown that screech tones from twin rectangular nozzles with double-beveled exit geometries can couple. Unlike coupling of twin rectangular jets of uniform geometry, the coupling here is more intricate because simultaneous multiple frequencies with a different spanwise modal structure are present. The coupling produces two frequencies, one of which is lower than the screech frequency of either jet. Although many coupling modes are kinematically permissible, the twin jets prefer two specific modes, and in some cases these two coupling modes coexist at different frequencies. Despite the geometric complexity we can effectively predict frequencies of tones from both single and twin coupled jets using the waveguide approach. It is hoped that these results and insights will assist those simulating screech for the purpose of tailoring shock-containing complex twin jets that minimize sonic fatigue failure of aircraft structures.
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- Title
- Batch process monitoring and its application to polymerization systems
- Creator
- Undey, C., Ertunc, S., Tatara, E., Teymour, F., Cinar, A.
- Date
- 2004-01
- Publisher
- WILEY-V C H VERLAG GMBH
- Description
-
Slight changes in raw material properties or operating conditions during critical periods of operation of batch and semi-batch polymerization...
Show moreSlight changes in raw material properties or operating conditions during critical periods of operation of batch and semi-batch polymerization reactors may have a strong influence on reaction mechanism and impact final product quality. Online process monitoring, fault detection, fault diagnosis, and product quality prediction in real-time ensure safe reactor operation and warn operators about excursions from normal operation that may lead to deterioration in product properties. Multivariate statistical process monitoring and quality prediction using multiway principal components analysis and multiway partial least squares have been successful in detecting abnormalities in process operation and product quality. When abnormal process operation is detected, fault diagnosis tools are used to determine the source cause of the deviation. Illustrative case studies are presented via simulated polyvinyl acetate polymerization.
Endnote format citation for DOI:10.1002/masy.200450210
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- Title
- Effect of Asymmetric Manipulations in Autocatalytic Networks
- Creator
- Balasubramanian, Sukanya, Cinar, Ali, Teymour, Fouad
- Date
- 2010-06-02
- Publisher
- AMER CHEMICAL SOC
- Description
-
In this paper, we show that heterogeneous networks can be configured and reconfigured to operate in flexible spatial patterns The concept is...
Show moreIn this paper, we show that heterogeneous networks can be configured and reconfigured to operate in flexible spatial patterns The concept is demonstrated by using a square grid of continuous stirred tank reactors with nearest neighbor interactions and hosting multiple cubic autocatalytic species Asymmetry is introduced in the system by allowing for different feed flow rates in the reactors. A heterogeneous system offers expanded phase space, improved stability. and coexistence characteristics The advantages of asymmetry are studied using bifurcation diagrams, continuation studies. and dynamics
Endnote format citation for DOI:10.1021/ie901096v
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- Title
- PLS, balanced, and canonical variate realization techniques for identifying VARMA models in state space
- Creator
- Negiz, A., Cinar, A.
- Date
- 1997-10
- Publisher
- ELSEVIER SCIENCE BV
- Description
-
This paper demonstrates the application of PLS regression, balanced realization, and canonical variate (CV) state space modeling techniques in...
Show moreThis paper demonstrates the application of PLS regression, balanced realization, and canonical variate (CV) state space modeling techniques in identifying stationary vector autoregressive moving average (VARMA) type of time series models in state space. An example VARMA process model is used to generate data, carry out modeling activities, and compare the three model development techniques. All realization methods provide equivalent state space models. Balanced realization can not handle singularities in the covariance matrix of past observations while all other methods can accommodate such singularities. Balanced realization and classical PLS do not provide minimal state variables that are orthogonal. 'Orthogonal states' PLS and canonical variate state space realization give orthogonal state variables that provide robust parameter estimates from real data, however the PLS method requires an additional singular value decomposition step.
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- Title
- MODE SPECTRA OF NATURAL DISTURBANCES IN A CIRCULAR JET AND THE EFFECT OF ACOUSTIC FORCING
- Creator
- Raman, G, Rice, Ej, Reshotko, E
- Date
- 1994-10
- Publisher
- SPRINGER VERLAG
- Description
-
A modal spectrum technique was used to study coherent instability modes (both axisymmetric and azimuthal) triggered by naturally occurring...
Show moreA modal spectrum technique was used to study coherent instability modes (both axisymmetric and azimuthal) triggered by naturally occurring disturbances in a circular jet. This technique was applied to a high Reynolds number (400,000) jet for both untripped (transitional) and tripped (turbulent) nozzle exit boundary layers, with both cases having a core turbulence level of 0.15%. The region up to the end of the potential core was dominated by the axisymmetric mode, with the azimuthal modes dominating further downstream. The growth of the azimuthal modes was observed closer to the nozzle exit for the jet with a transitional boundary layer. Whether for locally parallel flow or slowly diverging flow, even at low levels of acoustic forcing, the inviscid linear theory is seen to be inadequate for predicting the amplitude of the forced mode. In contrast, the energy integral approach reasonably predicts the evolution of the forced mode.
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- Title
- EVALUATION OF FLIP-FLOP JET NOZZLES FOR USE AS PRACTICAL EXCITATION DEVICES
- Creator
- Raman, G, Rice, Ej, Cornelius, Dm
- Date
- 1994-09
- Publisher
- ASME-AMER SOC MECHANICAL ENG
- Description
-
This paper describes the flowfield characteristics of the flip-flop jet nozzle and the potential for using this nozzle as a practical...
Show moreThis paper describes the flowfield characteristics of the flip-flop jet nozzle and the potential for using this nozzle as a practical excitation device. It appears from the existing body of published information that there is a lack of data on the parameters affecting the operation of such nozzles and on the mechanism of operation of these nozzles. An attempt is made in the present work to study the important parameters affecting the operation and performance of a flip-flop jet nozzle. Measurements were carried out to systematically assess the effect of varying the nozzle pressure ratio (NPR) as well as the length and volume of the feedback tube on the frequency of oscillation of this device. Flow visualization was used to obtain a better understanding of the jet flowfield and of the processes occurring within the feedback tube. The frequency of oscillation of the flip-flop jet depended significantly on the feedback tube length and volume as well as on the nozzle pressure ratio. In contrast, the coherent velocity perturbation levels did not depend on the above-mentioned parameters. The data presented in this paper would be useful for modeling such flip-flop excitation devices that are potentially useful for controlling practical shear flows.
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