作者:
O. SchoefsD. DochainR. ChapuisR. SamsonM. PerrierCESAME
Université Catholique de Louvain Ave Georges Lemaitre 4-6 B-1348 Louvain-la-Neuve Belgium Dept. of Civil
Geological and Mining Engineering École Polytechnique de Montréal P.O. Box 6079 Station Centre-ville Montreal (Qc) H3C 3A7 Canada Dept. of Chemical Engineering
École Polytechnique de Montréal P.O. Box 6079 Station Centre-ville Montreal (Qc) H3C 3A7 Canada
The goal of this study was to calibrate a numerical model aimed at describing simultaneous air and water flow in soil and, to build a model-based estimator of the unsaturated hydraulic conductivity. The experimental a...
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The goal of this study was to calibrate a numerical model aimed at describing simultaneous air and water flow in soil and, to build a model-based estimator of the unsaturated hydraulic conductivity. The experimental approach consisted of infiltration tests in a 1.5m high column of loamy sand. The numerical model correctly described water percolation without air convection, provided parameter adjustment of the predictive model of the unsaturated hydraulic conductivity was performed. An observer-based estimator was able to estimate on-line the hydraulic conductivity in steady-state but faced oscillation problems in unsteady-state. The difficulty in implementing the software-sensor can be explained by the strong nonlinearity of the dynamical model.
The aim of this paper consists in the implementation ofthe new adaptive control algorithm, dedicated for distributedparameter reactors, as the fully-configurable PC-based virtual controller. For this purpose the LabV...
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The aim of this paper consists in the implementation ofthe new adaptive control algorithm, dedicated for distributedparameter reactors, as the fully-configurable PC-based virtual controller. For this purpose the LabView graphical programming tool from National Instruments was used. Since the control law has a number of different parameters that must be set up to ensure its best control perfonnance, it is possible to configure these parameters by the controls placed at the front panels of this device. The most important properties of this virtual controller are presented in this paper.
Two approaches to solving the suboptimal Nehari problem are analyzed: the Grassmannian approach and a J -spectral factorization approach. Moreover, using the Grassmannian approach, a solution for the Hankel norm appro...
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Two approaches to solving the suboptimal Nehari problem are analyzed: the Grassmannian approach and a J -spectral factorization approach. Moreover, using the Grassmannian approach, a solution for the Hankel norm approximation problem is presented. The results apply to large classes of infinite-dimensional systems, and in particular to time-delay systems.
We investigate possibilities of choosing an activation policy of discrete scanning sensors in such a way as to maximize the accuracy of parameter estimation of a distributed system defined in a given multidimensional ...
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We investigate possibilities of choosing an activation policy of discrete scanning sensors in such a way as to maximize the accuracy of parameter estimation of a distributed system defined in a given multidimensional domain. A general functional defined on the Fisher information matrix is used as the design criterion. The setting examined here corresponds to situations where one has many sensors and activates only some of them during a given time interval, or alternatively, has several sensors which are mobile. The proposed approach, which has been suggested by Fedorov's idea of directly constrained design measures, consists in imposing constraints on the sensor density in a given spatial domain. As a result, an extremely fast iterative procedure is obtained whose each step reduces to replacing less informative sensor locations with points which furnish more informaton about the parameters. The performance of the proposed algorithm is evaluated by numerical experiments.
The operational water management of river reservoirs has to consider different and sometimes competitive objectives, e. g. navigation conditions, hydro-power generation, flood protection and environmental aspects. Des...
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The operational water management of river reservoirs has to consider different and sometimes competitive objectives, e. g. navigation conditions, hydro-power generation, flood protection and environmental aspects. Despite of problem specific extensions to cover the non-linear process behavior the application of local standard (PI) controllers to each reservoir can fulfill only basic management requirements. MBPC algorithms have the capability to give a wide and time proper exploitation of the active storage of the whole cascade. A two-layer control structure, consisting of a predictive controller in the upper layer and local controllers at each barrage, allows to provide the management decisions under real time conditions. Simulation results for three reservoirs of the river Moselle show the aptitude of the proposed approach.
A key bottleneck in the production of pharmaceuticals is in the formation of crystals from solution. The control of the crystal size distribution can be critically important for efficient downstream operations such as...
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A key bottleneck in the production of pharmaceuticals is in the formation of crystals from solution. The control of the crystal size distribution can be critically important for efficient downstream operations such as filtration and drying, and product effectiveness (e.g., bioavailability, tablet stability). This paper provides an overview of recent developments in the identification of pharmaceutical crystallization processes. This includes descriptions of recent activities in sensor technologies, model identification, experimental design, and robustness analysis of pharmaceutical crystallization processes.
A new approach to derive a finite element discretisation of PDE equations soley from observations is compared, in terms of approximation accuracy, with the standard finite element Galerkin approach which assumes knowl...
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A new approach to derive a finite element discretisation of PDE equations soley from observations is compared, in terms of approximation accuracy, with the standard finite element Galerkin approach which assumes knowledge of the governing PDE's. It is shown both in theory and by means of an example that, for a given model order, the identified model is more accurate than the equivalent finite element Galerkin approximation derived from the original PDE's.
This paper deals with the generalised approach to the adaptive control of a denitrifying biofilter with application of the substrate consumption rate. It is shown how to derive the control law on the basis of the simp...
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This paper deals with the generalised approach to the adaptive control of a denitrifying biofilter with application of the substrate consumption rate. It is shown how to derive the control law on the basis of the simplified form of the dynamical equation written for the controlled variable with the possibly minimal knowledge about the process kinetics and components. In this equation all reaction rates are replaced by the only one time varying parameter (substrate consumption rate) and its value is estimated on-line by the recursive least-squares method at the biofilter outlet to ensure the adaptability of the control law. The suggested methodology is evaluated by simulation with application to the complete nonlinear model of the biofilter.
The purpose of this paper is to show that a distributed-parameter model of a continuous ball mill can be developed by discretizing the particle size continuum into a few size intervals only. Despite this coarse discre...
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The purpose of this paper is to show that a distributed-parameter model of a continuous ball mill can be developed by discretizing the particle size continuum into a few size intervals only. Despite this coarse discretization of the particle size distribution, the ball mill model provides a good representation of the real process, which can be combined with a classifier model to build a complete simulator of a closed-loop grinding circuit. This simplified process representation is compared with a detailed first-principle model previously developed and validated by the authors. The main advantage of the simplified model is that it can be easily incorporated in an on-line control scheme. For illustrative purposes, a NMPC scheme is implemented to regulate the product fineness when variations in the grindability of the raw material occur as a measurable disturbance. The control objective, based on a size interval content, is compatible with traditional fineness measurements.
A non-classic optimality condition and numerical algorithm for smooth boundary controls in semi-linear first-order hyperbolic systems are presented. Additional integral control constraints are considered. The suggeste...
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A non-classic optimality condition and numerical algorithm for smooth boundary controls in semi-linear first-order hyperbolic systems are presented. Additional integral control constraints are considered. The suggested approach is based on special variations of admissible continuously differentiable controls. These variations lead to a new necessary optimality condition which is a base for a numerical method. The method is applied to an optimal control problem for an age-structured population.
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