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State profile estimation of an autothermal periodic fixed-bed reactor

CHEMICAL ENGINEERING SCIENCE 1998年第1期53卷 47-58页

作者： Hua, X Mangold, M Kienle, A Gilles, ED Univ Stuttgart Inst Syst Dynam & Regelungstech D-70550 Stuttgart Germany

In this paper, the state profile estimation of a novel autothermal fixed-bed reactor (called circulation loop reactor, CLR), which can be operated as an autonomous periodic system, is studied. Since in autothermal operation the reactor shows sustained large oscillations, its dynamics have to be modelled as a strongly nonlinear distributed parameter system. The generally used lumping techniques (e.g. the orthogonal collocation method) for designing the state estimator of fixed-bed reactors are not applicable in this case. An approach for estimating the state profiles of the CLR based on a nonlinear distributed parameter observer is presented. To decrease the computational effort of the observer in real-time applications, the reduction of the detailed model of the CLR is investigated. In order to achieve asymptotic stability and fast convergence of the observer, the observability of the CLR is analysed, and use of features of the sustained oscillatory system and physical insight are made. A method based on exponential weighting functions is proposed to approximate the observation error profile. The temperature and concentration profiles are estimated from a small number of temperature measurements. The obtained observer was successfully tested with the dynamic simulator DIVA in the cases of errors in the initial condition and the model parameters, random noisy measurements, and unknown disturbances, also including the different choice of sensor locations, and different observer parameters. It shows excellent dynamic tracking of the reactor profiles, strong robustness, and easy tuning. It forms a basis for developing appropriate control strategies of the CLR. (C) 1997 Elsevier Science Ltd.

关键词： fixed-bed reactors parameter estimation distributed parameter system nonlinear oscillations

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SPECTRAL BASIS THEORY FOR THE IDENTIFICATION OF STRUCTURAL DYNAMIC-systemS

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AIAA JOURNAL 1988年第6期26卷 726-732页

作者： FABUNMI, JA AEDAR Corporation New Carrollton Maryland

This paper presents the theoretical formulation of a technique for determining the mathematical model of structural dynamic systems. This technique utilizes the fact that the forced responses of a structure can be decomposed into linear combinations of sets of frequency-dependent functions. The orthonormatized forms of these functions, along with the associated transformation matrices, are used to obtain the unique pseudoinverse of the matrix of forced responses, which satisfies all the required Moore-Penrose conditions. Variations of this scheme can be used to determine: 1) the damping matrix, when the mass and stiffness matrices are known;2) the complex stiffness matrix, when the mass matrix is known;3) the mass matrix, when the stiffness matrix is known;and 4) the reduced-order mass and stiffness matrices, when the larger-order matrices are known. Discussed are problems of redundancy and overtruncation of dynamic models and possible methods of avoiding them. © 1988 American Institute of Aeronautics and Astronautics, Inc., All rights reserved.

关键词： Finite Element Analysis Mathematical Models Damping Coefficient Structural Response Condensation Structural Dynamics distributed parameter system Frequency Response Functions Three Degrees of Freedom Damping Mechanisms

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MOTOR CHARACTERISTICS IN THE CONTROL OF A COMPLIANT LOAD

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JOURNAL OF GUIDANCE CONTROL AND DYNAMICS 1986年第1期9卷 113-118页

作者： HAROKOPOS, EG MAYNE, RW SUNY BUFFALO DEPT MECH & AEROSP ENGNBUFFALONY 14260

This paper considers a servomechanism consisting of a DC-motor, a gear train and an inertial mass controlled through a compliant drive. The compliance is modeled as a spring between the gear box and inertia, and the interaction between the actuator and its load is considered. Dimensionless parameters are defined to describe this interaction, and the influence of the parameters on open- and closed-loop performance is discussed. system behavior is relatively sensitive to one particular dimensionless parameter related to damping provided by electromechanical interaction. Results of this effort illustrate the concept of quantitative controllability and indicate the possibility of controlling flexible loads conveniently by an appropriate choice of actuator parameters. (Author)

关键词： distributed parameter system Actuators Time Optimal Control Damping Ratio Numerical Optimization Dynamic Response Servo Motors Robotics Lumped parameter Model Numerical Simulation

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Linear control of electrochemical tubular reactor system-Removal of Cr(VI) from wastewaters

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JOURNAL OF THE TAIWAN INSTITUTE OF CHEMICAL ENGINEERS 2011年第3期42卷 498-505页

作者： Wu, Wei Peng, Jiyan-Jh Natl Yunlin Univ Sci & Technol Dept Chem & Mat Engn Yunlin 64002 Taiwan

An electrochemical tubular reactor system, which is used to remove the hexavalent chromium Cr(VI) from wastewaters, is presented. Under specific modeling and operating constraints, the axial dispersion reactor is described by the coupled nonlinear partial differential equations (PDEs) under Danckwerts boundary conditions. Through the composite finite difference combination, the lumped differential-algebraic equations (DAEs) turn out to be a two-input/two-output system. The overall system stability analysis is investigated via the Lyapunov's first method. According to the prescribed control configuration, the closed-loop simulation shows that a multi-loop PID control scheme can ensure the outlet concentration of Cr(VI) less than 0.5 mg/L in wastewaters. (C) 2010 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.

关键词： distributed parameter system Dynamic simulation PID control Wastewater treatment

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Multi-scale local LSSVM based spatiotemporal modeling and optimal control for the goethite process

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NEUROCOMPUTING 2020年第0期385卷 88-99页

作者： Dai, Jiayang Chen, Ning Luo, Biao Gui, Weihua Yang, Chunhua Cent South Univ Sch Automat Changsha 410083 Peoples R China Peng Cheng Lab Shenzhen 518000 Peoples R China

The iron removal process by goethite is an important part of zinc hydrometallurgy. In existing works, the goethite process is often modeled as a lumped parameter system, where the spatial distribution information of reactants is not involved. In this paper, the spatiotemporal modeling of the goethite process and its optimal control problem are studied. To make the infinite-dimensional distributed parameter system easier to solve, space-time separation is adopted to transform it into a finite-dimensional system. Then, a multi-scale local least squares support vector machine is proposed to establish the temporal model. This method uses multi-scale kernel learning to deal with different trends of the process and establish a local model to track the state change of the system. Through space-time synthesis, the established spatiotemporal model can approximate the distributed parameter system of the goethite process. Moreover, an optimal control strategy based on the spatiotemporal model is designed to reduce the cost of oxygen and zinc oxide consumed in the process. Finally, simulation experiments on the goethite process demonstrate the effectiveness of the proposed modeling method and optimal control strategy. (C) 2019 Elsevier B.V. All rights reserved.

关键词： distributed parameter system Iron removal process Least squares Multi-scale kernel learning Spatiotemporal modeling Support vector machine

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FINITE-ELEMENT MODELING OF PIEZOELECTRIC SENSORS AND ACTUATORS

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AIAA JOURNAL 1993年第5期31卷 930-937页

作者： HWANG, WS PARK, HC Pohang Institute of Science and Technology Pohang 790-600 Republic of Korea

A finite element formulation for vibration control of a laminated plate with piezoelectric sensors/actuators is presented. Classical laminate theory with the induced strain actuation and Hamilton's principle are used to formulate the equations of motion. The total charge developed on the sensor layer is calculated from the direct piezoelectric equation. The equations of motion and the total charge are discretized with four-node, 12-degree-of-freedom quadrilateral plate bending elements with one electrical degree of freedom. The piezoelectric sensor is distributed, but is also integrated since the output voltage is dependent on the integrated strain rates over the sensor area. Also, the piezoelectric actuator induces the control moments at the ends of the actuator. Therefore, the number, size, and locations of the sensors/actuators are very important in the control system design. By selective assembling of the element matrices for each electrode, responses with various sensor/actuator geometries can be investigated. The static responses of a piezoelectric bimorph beam are calculated. For a laminated plate under the negative velocity feedback control, the direct time responses are calculated by the Newmark-beta method, and the damped frequencies and modal damping ratios are derived by modal state space analysis.

关键词： Finite Element Formulation Piezoelectric Actuators Piezoelectric Sensors Free Vibrations Feedback Control Loop Vibration Control Control system Design Strain Rate Fiber Reinforced Composites distributed parameter system

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Control optimization in a hyperbolic linear system

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COMPUTATIONAL MATHEMATICS AND MATHEMATICAL PHYSICS 2012年第1期52卷 4-19页

作者： Tyatyushkin, A. I. Russian Acad Sci Siberian Branch Inst Syst Dynam & Control Theory Irkutsk 664033 Russia

An optimal control problem is considered for a distributed-parameter Goursat-Darboux system with controlled boundary conditions. For the numerical solution of the problem, an algorithm based on separability and minimax theorems is constructed, which reduces the problem to finding the maximum of a concave functional defined in the class of one-variable functions.

关键词： numerical algorithm optimal control distributed parameter system

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Spillover suppression via eigenstructure assignment in large flexible structures

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JOURNAL OF GUIDANCE CONTROL AND DYNAMICS 2002年第3期25卷 599-602页

作者： Choi, JW Park, US Pusan Natl Univ Sch Mech Engn Pusan 609735 South Korea Pusan Natl Univ Res Inst Mech Technol Pusan 609735 South Korea Osaka Univ Grad Sch Engn Dept Comp Controlled Mech Syst Suita Osaka 5650871 Japan

A new spillover suppression method using eigenstructure assignment was developed. The resulting method can prevent possible instability in the active control of large flexible structures caused by the neglected dynamics of the higher modes of vibration by reducing their detrimental effect of spillover. In simulation, by comparison of two cases of observer design, the resulting method was proven to be successful in the spillover suppression of large flexible structures.

关键词： Flexible Structures distributed parameter system Ecliptic Feedback Control system Astronomical Unit Propellant Limited Computing Resources Active Vibration Control Control system Design Electric Propulsion

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SLIDING MODE CONTROL IN INDEFINITE-DIMENSIONAL systemS

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AUTOMATICA 1987年第6期23卷 753-757页

作者： ORLOV, YV UTKIN, VI Institute of Control Sciences 65 Profsoyuznaya GSP-312 Moscow U.S.S.R.

A mathematical description of motion in a sliding mode is considered for systems with discontinuous controls described by differential equations in Banach space. Applying the regularization principle to such systems the sliding mode equations are obtained. For a set of interconnected heat processes the control system with the prescribed dynamics is designed through deliberate introduction of sliding modes.

关键词： decoupling distributed parameter system disturbance rejection Sliding states stability

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Neural Network-Based Cooperative Trajectory Tracking Control for a Mobile Dual Flexible Manipulator

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IEEE TRANSACTIONS ON NEURAL NETWORKS AND LEARNING systemS 2023年第9期34卷 6545-6556页

作者： Zhang, Shuang Wu, Yue He, Xiuyu Wang, Jingyuan Univ Sci & Technol Beijing Sch Automat & Elect Engn Beijing 100083 Peoples R China Univ Sci & Technol Beijing Inst Artificial Intelligence Beijing 100083 Peoples R China Univ Sci & Technol Beijing Shunde Grad Sch Foshan 528300 Peoples R China

For a mobile dual flexible manipulator (MDFM) system, this article focuses on the problem of cooperative trajectory tracking under unknown dynamics and time-varying trajectories. The dynamic model of the wheeled mobile manipulator system in 2-D space is established. Taking into account the unmodeled dynamics of the system, unknown terms of the system are approximated by integrating the radial basis function neural network (RBFNN) structure. By introducing the servo system, the cooperative trajectory tracking control (CTTC) strategy is designed, which realizes the system's cooperative operation, time-varying trajectory tracking, and vibration suppression. The performance of the proposed control scheme is verified through theoretical analysis and numerical simulations.

关键词： Manipulator dynamics Neural networks Vibrations Uncertainty Mathematical models Trajectory tracking Trajectory Boundary cooperative control distributed parameter system mobile dual flexible manipulator (MDFM) radial basis function neural network (RBFNN) trajectory tracking control

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