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作者： Koziel, Slawomir Bandler, John W. Madsen, Kaj Simulation Optimization Systems Research Laboratory Department of Electrical and Computer Engineering McMaster University Hamilton ON L8S 4K1 Canada Bandler Corporation Dundas ON L9H 5E7 Canada Informatics and Mathematical Modelling Technical University of Denmark Lyngby DK-2800 Denmark

One of the central issues in space mapping optimization is the quality of the underlying coarse models and surrogates. Whether a coarse model is sufficiently similar to the fine model may be critical to the performance of the space mapping optimization algorithm and a poor coarse model may result in lack of convergence. Although similarity requirements can be expressed with proper analytical conditions, it is difficult to verify such conditions beforehand for real-world engineering optimization problems. In this paper, we provide methods of assessing the quality of coarse/surrogate models. These methods can be used to predict whether a given model might be successfully used in space mapping optimization, to compare the quality of different coarse models, or to choose the proper type of space mapping which would be suitable to a given engineering design problem. Our quality estimation methods are derived from convergence results for space mapping algorithms. We provide illustrations and several practical application examples. © Springer Science+Business Media, LLC 2007.

关键词： Optimization

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Elemental Iron Fe° for better drinking water in rural areas of developing countries

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5th International Conference on Uranium Mining and Hydrogeology, UMH 2008

作者： Noubactep, Chicgoua Woafo, P. Angewandte Geologie Universität Göttingen Goldschmidtstraße 3 D - 37077 Göttingen Germany Kultur und Nachhaltige Entwicklung CDD E.V S/c S.M. Youmbi Peka Bonhoefferweg 2 D - 37075 Göttingen Germany Laboratory of Modelling and Simulation in Engineering and Biological Physics Faculty of Science University of Yaounde I Box 812 Yaounde Cameroon

ISBN: (纸本)9783540877455

Many of the reasons behind the anthropogenic contamination problems in rural environments of developing countries lie in changes in the traditional way of life and the ignorance on the toxic potential of introduced manufactured products. A generalization trend exists within the international community suggesting that water in developing countries is of poor quality. However, the water quality is rarely analytically determined. Existing potabilization solutions may be prohibitively expensive for the rural populations. Therefore, efficient and affordable technologies are still needed to ameliorate the water quality. In the recent two decades, elemental iron has shown the capacity to remove all possible contaminants (including vimses) from the groundwater. This paper presents a concept to scale down the conventional iron barrier technology to meet the requirements of small communities and households in rural environments worldwide.

关键词： Developing countries

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Pole placement approaches for linear and fuzzy systems

Pole placement approaches for linear and fuzzy systems

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International Symposium on Intelligent Systems and Informatics (SISY)

作者： S. Preitl R.-E. Precup P. A. Clep I.-B. Ursache J. Fodor I. Skrjanc Department of Automation and Applied Informatics Polytechnic슠University of Timisoara Timisoara Romania Institute of Intelligent Engineering Systems Budapest Tech Polytechnical Institution Budapest Hungary Laboratory of Modelling Simulation and Control University of Ljubljana Ljubljana Slovenia

The paper investigates several pole placement methods in the linear case and suggests a new pole placement method by means of fuzzy linear equations. The linear methods concern the constant real part poles, the poles places on a circle, Butterworth configurations without and with the correction of the imaginary part, the pole-zero cancellation, and the poles placed on an ellipse. Low order systems are considered. The pole placement methods are compared by the digital simulation of control systemspsila behaviors with respect to the modification of the reference input. The conclusions are useful for continuous control systems, and they can be extended easily to digital control systems including quasi-continuous ones.

关键词： State feedback Fuzzy systems Control systems Equations Poles and zeros Control system synthesis Stability Digital control Nonlinear control systems Automation

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Control engineering: New Trends with OO modelling Approach

Control Engineering: New Trends with OO Modelling Approach

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Asia International Conference on Modeling & simulation

作者： Borut Zupancic Rihard Karba Laboratory for Modelling Simulation and Control Faculty of Electrical Engineering University of Ljubljana Ljubljana Slovenia

The paper deals with two examples, which show the efficiency of OO modelling approach in control engineering. The first example - an optimization of three tank hydraulic control system shows the efficiency of the OO modelling approach in control engineering education. A very efficient environment is the combination of Matlab Simulink and a Modelica based OO environment Dymola. Two different control strategies - PID and cascade control are demonstrated. The second example shows the efficiency of OO modelling approach in an industrial application. DYMOLA-Modelica was efficiently used for studying a pendulum system in a stone wool production technology in a Slovenian company. In this system linear (horizontal) movement of a bottom edge of the pendulum system is a very important technological feature in forming the secondary wool layer. The simulation results showed that it is possible to achieve more appropriate movements with regard to position and velocity

关键词： Control engineering Mathematical model Object oriented modeling Computer languages Laboratories Control engineering education Wool Connectors Temperature Process control

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Impact Of Elastic Modulus Degradation On Springback In Sheet Metal Forming

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AIP Conference Proceedings 2007年第1期908卷 925-930页

作者： Miroslav Halilovič Marko Vrh Boris Štok 1Laboratory for Numerical Modelling & Simulation Faculty of Mechanical Engineering University of Ljubljana Ljubljana — Slovenia 2Kovinoplastika Lož Stari trg pri Ložu — Slovenia

Strain recovery after removal of forming loads, commonly defined as springback, is of great concern in sheet metal forming, in particular with regard to proper prediction of the final shape of the part. To control the problem a lot of work has been done, either by minimizing the springback on the material side or by increasing the estimation precision in corresponding process simulations. Unfortunately, by currently available software springback still cannot be adequately predicted, because most analyses of springback are using linear, isotropic and constant Young’s modulus and Poisson’s ratio. But, as it was measured and reported, none of it is true. The aim of this work is to propose an upgraded mechanical model which takes evolution of damage and related orthotropic stiffness degradation into account. Damage is considered by inclusion of ellipsoidal cavities, and their influence on the stiffness degradation is taken in accordance with the Mori‐Tanaka theory, adopting the GTN model for plastic flow. In order to improve the numerical springback prediction, two major things are important: first, the correct evaluation of the stress‐strain state at the end of the forming process, and second, correctness of the elastic properties used in the elastic relaxation analysis. Since in modelling of the forming process we adopt a damage constitutive model with orthotropic stiffness degradation considered, a corresponding damage parameters identification upon specific experimental tests data must be performed first, independently of the metal forming modelling. An improved identification of material parameters, which simultaneously considers tensile test results with different type of specimens and using neural network, is proposed. With regard to the case in which damage in material is neglected it is shown in the article how the springback of a formed part differs, when we take orthotropic damage evolution into consideration.

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Approaches To modelling Of Elastic Modulus Degradation In Sheet Metal Forming

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AIP Conference Proceedings 2007年第1期907卷 239-244页

作者： Marko Vrh Miroslav Halilovič Boris Štok 1Kovinoplastika Lož Stari trg pri Ložu — Slovenia 2Laboratory for Numerical Modelling & Simulation Faculty of Mechanical Engineering University of Ljubljana Ljubljana — Slovenia

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Synchronization in a ring of four mutually coupled van der Pol oscillators: Theory and experiment

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Physical Review E 2006年第4期74卷 046213-046213页

作者： B. Nana P. Woafo []Laboratory of Nonlinear Modelling and Simulation in Engineering and Biological Physics Faculty of Science University of Yaounde I Box 812 Yaounde Cameroon

We investigate different states of synchronization in a ring of four mutually coupled van der Pol oscillators. The stability analysis and numerical simulation are performed to determine the suitable coupling parameters leading to high-quality synchronization. The consequences of parameter mismatch are also highlighted. Experimental realization is then used to show the existence of complete and partial synchronization.

关键词： CENTRAL PATTERN GENERATORS CHAOTIC SYSTEMS ANIMAL GAITS LOCOMOTION

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MULTI MODEL APPROACH TO MULTIVARIABLE LOW ORDER STRUCTURED-CONTROLLER DESIGN

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IFAC Proceedings Volumes 2006年第2期39卷 1021-1026页

作者： M. Escobar J.O. Trierweiler Laboratory of Process Control and Integration (LACIP) Group of Integration Modelling Simulation Control and Optimization of Processes (GIMSCOP) Department of Chemical Engineering Federal University of Rio Grande do Sul

The method presented here offers an effective and time saving tool for robust low order multivariable controller design. The relation between controller complexity and closed loop performance can easily be evaluated. The method consists of five steps: 1. A desired behavior of the closed loop system is specified. Considering the nonminimum phase part of the process model the closed loop attainable performance is determined. 2. The process model and the attainable performance are scaled by the RPN-scaling procedure. 3. This defines an “ideal” scaled controller, which is usually too complex to be realized. 4. The frequency response of the ideal scaled compensator is approximated by a simpler one with structure and order chosen by the user. 5. Since the approximation in frequency response is performed with the scaled system, it is necessary to return to the original system's units. This procedure can be implemented using a multi-model approach, what increase the robustness of synthesized controller.

关键词： multivariable project design frequency domain multi models low order controllers

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Coupled fluid-structure simulation of the Coriolis flowmeter under forced vibration

Coupled fluid-structure simulation of the Coriolis flowmeter...

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10th International Conference on Civil, Structural and Environmental engineering Computing, Civil-Comp 2005

作者： Mole, N. Bobovnik, G. Kutin, J. Štok, B. Bajsić, I. Laboratory for Numerical Modelling and Simulation Faculty of Mechanical Engineering University of Ljubljana Slovenia Laboratory of Measurements in Process Engineering Faculty of Mechanical Engineering University of Ljubljana Slovenia

ISBN: (纸本)1905088000

A fluid conveying measuring straight-tube that is maintained vibrating at its first natural frequency under imposed forced vibration conditions is a primary sensing element in tube Coriolis flowmeter. To enable a periodic operation of the flowmeter a point in the central cross-section of the measuring tube is harmonically excited. An investigation of this coupled fluid-structure interaction, based on a coupled finite volume (FV) - finite element (FE) numerical model and subsequent computer simulation, has been done for several mass flowrates. To obtain a rather fast numerical steady-state response at sensor locations under forced vibration conditions a special numerical procedure has been developed, thus enabling design sensitivities studies of the considered Coriolis flowmeters to be performed basically by computation. © 2005 Civil-Comp Press.

关键词： Fluid structure interaction

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Transient growth: Experiments, DNS and theory

Transient growth: Experiments, DNS and theory

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4th International Symposium on Turbulence and Shear Flow Phenomena, TSFP 4

作者： Ergin, F. Gökhan Choudhari, Meelan Fischer, Paul Tumin, Anatoli Mechanical and Aerospace Engineering Department Case Western Reserve University Cleveland OH 44106 United States Computational Modelling and Simulation Branch NASA Langley Research Center Hampton VA 23681 United States Mathematics and Computer Science Division Argonne National Laboratory Argonne IL 60439 United States Department of Aerospace and Mechanical Engineering University of Arizona Tucson AZ 85721 United States

Transient growth of linearly stable disturbances is believed to play an important role in the subcritical transition of laminar boundary layers and the self-sustained nature of boundary layer fluctuations in a fully turbulent flow. Prior work on transient growth has focused on identifying the optimum initial disturbances that result in maximum transient growth. This paper addresses the companion issue of receptivity of those disturbances, the mechanism that determines the actual magnitudes of transient growth that are realized in a given physical situation. A synergistic combination of experimental, computational, and theoretical approaches is used to quantify the flow receptivity to surface roughness in a Blasius boundary layer. Results reveal the non-optimality of the transient growth factors involved as well as the sensitive dependence of flow perturbations to the geometric characteristics of the roughness distribution. Direct numerical simulations (DNS) are compared in detail with experimental results, results obtained from linear receptivity theory and optimal disturbance calculations. DNS shows good agreement with the experimental results. Differences between the linear theory and DNS are attributed to nonlinear receptivity mechanisms. Results also support the proposal by Fransson et al. (2004) that disagreement between optimal disturbances and experiments/DNS may be attributed to differences involving the wall normal location of the streamwise vortex initiating the transient growth.

关键词： Laminar boundary layer

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