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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: 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: VIBRATIONAL STABILIZATION OF A CHEMICAL REACTOR - AN EXPERIMENTAL-STUDY
Creator: Cinar, A., Deng, J., Meerkov, S. M., Shu, X. S.
Date: 1987-04
Publisher: IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
Description: Vibrational control is a method for modification of dynamic properties of linear and nonlinear systems by introduction of fast, zero-average...
Show moreVibrational control is a method for modification of dynamic properties of linear and nonlinear systems by introduction of fast, zero-average oscillations in a system's parameters. It has been previously shown that forced oscillations introduced in the reactant flow rates to a continuous stirred tank reactor (CSTR) cause a modification of theS- shaped steady-state curve. In the present note experimental evidence is given to show that this modification leads to the operation the CSTR at an asymptotically stable periodic regime located near an unstable steady-state of the reactor system having fixed flow rates. For a given average stabilized state, such a stabilizing mechanism results in a higher production rate or lower energy expenditure compared to a steady operation with shifted input conditions.
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Title: 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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