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Quadratic stability of process systems in generalized lotka-volterra form

IFAC Proceedings Volumes 2004年第13期37卷 1217-1222页

作者： A. Magyar G. Szederkényi K.M. Hangos Process Control Research Group Systems and Control Laboratory Computer and Automation Research Institute HAS H-1518 P.O. Box 63 Budapest Hungary Tel.: +361 2796000； fax: +361 466 7503 Department of Computer Science University of Veszprém H-8200 Egyetem u. 10 Veszprém Hungary Tel.: +***； fax: +***

The global and local stability of process systems in generalized Lotka-Volterra form is studied in this paper using entropy-like and quadratic Lyapunov function candidates. The global stability check for LV models is performed by solving an LMI for a diagonal positive semi-definite matrix using singular perturbation technique. It is shown that a quadratic Lyapunov function can also be determined by solving linear matrix inequalities (LMIs). In addition, the quadratic stability neighborhood is convex in the space of the quasi-monomials and can be estimated by computing its corner points using LMIs. Furthermore, it is proved that quadratic stability with a diagonal weighting matrix enables to construct a dissipative-Hamiltonian description of the system. The developed methods are illustrated on the model of a continuously stirred tank reactor with a nonlinear reaction system.

关键词： quasi-polynomial systems Lotka-Volterra systems stability analysis linear matrix inequalities Hamiltonian systems

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Nonlinear analysis and control of a continuous fermentation process

Nonlinear analysis and control of a continuous fermentation ...

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作者： Szederkényi, G. Kristensen, N.R. Hangos, K.M. Bay Jørgensen, S. Systems and Control Research Laboratory Computer and Automation Institute HAS P.O. Box 63 H-1518 Budapest Hungary Department of Chemical Engineering Technical University of Denmark DK-2800 Lyngby Denmark

Different types of nonlinear controllers are designed and compared for a simple continuous bioreactor operating near optimal productivity. This operating point is located close to a fold bifurcation point. Nonlinear analysis of stability, controllability and zero dynamics is used to investigate open-loop system properties, to explore the possible control difficulties and to select the system output to be used in the control structure. A wide range of controllers are tested including pole placement and LQ controllers, feedback and input-output linearization controllers and a nonlinear controller based on direct passivation. The comparison is based on time-domain performance and on investigating the stability region, robustness and tuning possibilities of the controllers. controllers using partial state feedback of the substrate concentration and not directly depending on the reaction rate are recommended for the simple fermenter. Passivity based controllers have been found to be globally stable, not very sensitive to the uncertainties in the reaction rate and controller parameter but they require full nonlinear state feedback. © 2002 Published by Elsevier Science Ltd.

关键词： Fermentation

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LPV-modeling of a low-power gas turbine

LPV-modeling of a low-power gas turbine

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8th Mini Conference on Vehicle System Dynamics, Identification and Anomalies, VSDIA 2002

作者： Ailer, Piroska Szederkényi, Gábor Hangos, Katalin M. Aviation Technical Institute Miklós Zrínyi National Defence University POB. 1 H-5008 Szolnok Hungary Systems and Control Laboratory Computer and Automation Research Institute HAS POB. 63 H-1518 Budapest Hungary

The nonlinear dynamic model of gas turbines is derived from first engineering principles, which consists of differential conservation balances completed by algebraic constitutive relations. This nonlinear dynamic model can then be transformed into input-affine form. The coordinate-functions of the state equation f(x) have very complicated algebraic structures, while the functions gi,(x) are constants. Because of this fact, the nonlinear dynamic analysis of the model, such as investigation of controllability and stability, can only be performed with difficulty or in some cases it can not be done. To solve this problem and to investigate the controllability and stability of the model in a more effective way the nonlinear dynamic model has to be transformed into LPV (Linear Parameter-Varying) model. This LPV-model can then be effectively used to develop some types of controllers to improve the dynamic response of the engine. In this paper we show the possible ways and steps of the transformation being neither obvious nor unique and the final form of the LPV-model of a pilot-plant gas turbine, which is installed in the Budapest University of Technology and Economics. Department of Aircraft and Ships on a test stand.

关键词： Gas turbines

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Intelligent assumption retrieval from process models by model-based reasoning 1

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14th International Conference on Industrial and Engineering Applications of Artificial Intelligence and Expert systems, IEA/AIE 2001

作者： Lakner, R. Hangos, K.M. Dept. of Computer Science University of Veszprém Veszprém Hungary Systems and Control Laboratory Computer and Automation Research Institute HAS Budapest Hungary

ISBN: (数字)9783540455172

ISBN: (纸本)3540422196

Process models can be seen as structured knowledge base elements with syntax and semantics dictated by the underlying physical and chemical laws. The effect of model simplification assumptions is then determined by forward reasoning in order to take into account all of their implications. A bidirectional reasoning method for the retrieval of modelling assumptions from two related process models is proposed. An intelligent model editor is constructed to perform and test the model-based reasoning methods related to the assumption retrieval. © Springer-Verlag Berlin Heidelberg 2001.

关键词： Semantics

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Grey box process modelling for fault detection and isolation

Grey box process modelling for fault detection and isolation

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1999 European control Conference, ECC 1999

作者： Hangos, K.M. Szederkenyi, G. Systems and Control Laboratory Computer and Automation Research Institute HAS PO Box 63 BudapestH-1518 Hungary

ISBN: (纸本)9783952417355

The effect of the type and quality of process models applied for fault detection and isolation is investigated in this paper. It is shown that the level of details and the modelled processes within the applied grey box model determine the detectability of the faults as well as the sensitivity and detection delay of a particular fault detection method. The concepts and results are illustrated on the example of fault detection of heat exchange surface deterioration and leaking in a countercurrent heat exchanger. © 1999 EUCA.

关键词： Fault detection

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Simultaneous Fault Detection Of Heat Exchangers

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IFAC Proceedings Volumes 1998年第10期31卷 365-370页

作者： Gcibor Szederkényi Erik Weyer Katalin M. Hangos Dept. of Computer Science University of Veszprem H-8201 Veszprem Egyetem u. 3. Hungary Dept. of Electrical and Electronic Engineering The University of Melbourne Parkville VIC 3052 Australia Systems and Control Research Laboratory Computer and Automation Institute HAS H-1518 Budapest PO Box 63 Hungary

A grey box model-based method for fault diagnosis is proposed in this paper. The method is based on a first principle model of the process unit: a heat exchanger, and on a grey box model of the faults: the deterioration of the heat transfer surface by aging and the leaking of the outer container. The deterioration of the heat transfer surface is due to material settling, and in old heat exchangers pieces of this material can break off and cause damage in the equipment. A recursive least squares estimator with forgetting factor is used to track both the heat transfer coefficients and the cold side volume. The heat transfer coefficients are estimated both from the hot and cold side equations. The settled material breakage fault is detected via detection of abrupt positive jumps in the estimated heat transfer coefficients using a detector based on a cumulative sum (CUSUM) test. The proposed method enables simultaneous detection of the two fault types considered. Fault localization along the equipment length is also possible when temperature measurements are available along the length.

关键词： Fault detection Fault isolation Fault location Process model Grey box modelling Identification

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Grey Box Fault Detection in Heat Exchanger Networks

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IFAC Proceedings Volumes 1997年第18期30卷 191-196页

作者： E. Weyer K.M. Hangos Dept. of Chemical Engineering University of Queensland Brisbane QLD 4072 Australia Systems and Control Research Laboratory Computer and Automation Institute HAS H-1518 Budapest PO Box 63 Hungary

A grey box model-based method for fault diagnosis is proposed in this paper which is based on a first principle model of the process unit: a heat exchanger, and on a grey box model of the fault: the deterioration of the heat transfer surface by aging. Under normal operating conditions the heat transfer coefficient is constant or slowly decreasing due to a layer of settled material building up on the heat transfer surface, and we propose to use a recursive least squares estimator with forgetting factor to track the heat transfer coefficients during these stages. In old heat exchangers, big chunks of the settled material can break away from the surface causing the heat transfer coefficients to rise sharply. This fault is detected via detection of abrupt positive jump in the estimated heat transfer coefficients using a Hinkley detector

关键词： Fault diagnosis grey box modelling fault modelling identification

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Developing a prototype concurrent design tool for composite topside structures

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NAVAL ENGINEERS JOURNAL 1997年第3期109卷 279-290页

作者： Dirlik, S Hambric, S Azarm, S Marquardt, M Hellman, A Bartlett, S Castelli, V Steve Dirlik:began his career at the Naval Surface Warfare Center Carderock Division in 1981 as an aerospace engineer co-op student. He completed his bachelor of science degree in aeropace and ocean engineering from Virginia Polytechnic Institute and State University in 1985 and his master of science degree in aerospace engineering from the University of Maryland in 1990. Mr. Dirlik recently completed a master of science program in applied physics at The Johns Hopins University and currently works in the Radar Cross Section and Target Physics Branch of the Signatures Directorate at the Naval Surface Warfare Center Corderoke Division. He has worked on Navy low observable programs since 1990. Stephen Hambric:is a research associate at the Applied Research Laboratory at The Pennsylvania State University. He received his B. S. and M.S. degree in mechanical engineering from Virginia Polytechnic Institute and State University and his D. Sc. in mechnical engineering from the George Washington University. He has worked on several computer aided multidiscikplinary design and optimization projects over the years including an automated propeller design system and a structural acoustic optimization capability. Dr. Shpour Azarm:is currently working as an associate professor with the Design and Manufacturing Group of the Department of Mechanical Engineering at the University of maryland at College Park. Dr Azarm's expertise is in the areas of optimization-based designed and concurrent design and optimization of multidisciplinary systems. He was a consultant at Black & Decker Corporation (summer 1996) and worked as a Navy senior summer faculty fellow (summer 1995) and a NASA summer faculty fellow (summer 1994). He was a visiting scientist at NASA Langley Research Center for Multidisciplinary Analysis and Applied Structural Optimzatiom at the University of Siegen in Germany (spring 1992) and the Design Institute of the Technical University of Denmark (summer 1990). Dr Azarm was an associate technical editor of the ASME Jour

A prototype concurrent engineering tool has been developed for the preliminary design of composite topside structures for modern navy warships. This tool, named GELS for the Concurrent Engineering of Layered Structures, provides designers with an immediate assessment of the impacts of their decisions on several disciplines which are important to the performance of a modern naval topside structure, including electromagnetic interference effects (EMI), radar cross section (RCS), structural integrity, cost, and weight. Preliminary analysis modules in each of these disciplines are integrated to operate from a common set of design variables and a common materials database. Performance in each discipline and an overall fitness function for the concept are then evaluated. A graphical user interface (GUI) is used to define requirements and to display the results from the technical analysis modules. Optimization techniques, including feasible sequential quadratic programming (FSQP) and exhaustive search are used to modify the design variables to satisfy all requirements simultaneously. The development of this tool, the technical modules, and their integration are discussed noting the decisions and compromises required to develop and integrate the modules into a prototype conceptual design tool.

关键词： Warships

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Grey-Box Modeling for Identification and control: An Emerging Discipline or an Established Technology?

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IFAC Proceedings Volumes 1994年第8期27卷 1193-1198页

作者： S. Bay Jorgensen K.M. Hangos Department of Chemical Engineering Technical University of Denmark Systems and Control Research Laboratory: Computer and Automation Institute HAS

Grey box modeling is a widely used term, which presently reflects that both a priori and experimental knowledge is being incorporated into the model building process. A brief investigation into various uses of grey box modeling approaches reveals that they mainly differ with respect to the required model accuracy. The goal of the model application also has to be considered in the model building, since it constrains the necessary accuracy required by the model. In this paper these two viewpoints are combined thus leading to a proposed new definition of grey box modeling.

关键词： Qualitative differential and algebraic equations Uncertainty representation Verbatim models Robust identification and control Modeling cycle

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Grey Box Identification of Vehicle Dynamics

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IFAC Proceedings Volumes 1994年第8期27卷 1187-1192页

作者： L. Gianone J. Bokor K.M. Hangos Systems and Control Laboratory Computer and Automation Research Institute HAS H-1518 Budapest P.O.B. 63 Hungary

The parametnzation and identification of vehicle vibrating structures are discussed in this paper. The determination of physical parameters from the abstract parameters that represent free coefficients in a transfer function or state space model of the vehicle is investigated for the axle subsystems. The situation when some of the coefficients are known a priori, and also there are certain dependences, possibly nonlinear, among some physical parameters is investigated. Related to this grey box problem, an identification scheme is proposed to obtain the physical parameters from the unconstrained estimates of the abstract parameters of the axle models.

关键词： Vehicles suspension system physical modeling grey box parameter estimation instrumental variable method

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