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Parameter identification of hardening laws for bulk metal forming using experimental and numerical approach

INTERNATIONAL JOURNAL OF MATERIAL FORMING 2016年第1期9卷 21-33页

作者： Gruber, Maxime Lebaal, Nadhir Roth, Sebastien Harb, Nizar Sterionow, Peter Peyraut, Francois Belfort Montbeliard Univ Technol IRTES M3M Belfort Montbeliard France Tech Univ Munich Inst Met Forming & Casting D-80290 Munich Germany

The simulative prediction of material behaviour in forming processes necessitates a precise determination of the material parameters. The present work focusses on the modelling of the isostatic part of the flow stress using a flow curve with an analytical suppression of the influence of friction and an adequate analytical law. The experimental data are obtained from isothermal upsetting tests with various upsetting ratios. The different ratios are based on a variation of the height of the sample, remaining the diameter constant. For the proposed flow stress law five parameters are identified. In order to decrease the number of function evaluations, a new reduction model method based on both analytical and sequential quadratic programming (SQP) algorithms is developed and applied to identify flow stress law parameters. A comparison with traditional SQP algorithm is also done. A 3D finite element model is built in order to simulate a side pressing test and an experimental validation is done. As numerical results fit very well experimental data, the proposed model achieves a precise prediction of the flow behaviour. The identification of the other parts of the model (i.e. dependencies on strain-rate and temperature) are conducted in further works.

关键词： Flow stress Friction identification algorithm Optimization Finite element analysis

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Automatic identification of Oceanic Multieddy Structures From Satellite Altimeter Datasets

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IEEE JOURNAL OF SELECTED TOPICS IN APPLIED EARTH OBSERVATIONS AND REMOTE SENSING 2015年第4期8卷 1555-1563页

作者： Yi, Jiawei Du, Yunyan Zhou, Chenghu Liang, Fuyuan Yuan, May Chinese Acad Sci Inst Geog Sci & Nat Resources Res State Key Lab Resources & Environm Informat Syst Beijing 100101 Peoples R China Western Illinois Univ Dept Geog Macomb IL 61455 USA Univ Texas Dallas Sch Econ Polit & Policy Sci Richardson TX 75080 USA

Very few of current eddy detection algorithms are capable of identifying multieddy structures resulted from interactions among eddies. In this study, we improve our previous hybrid detection (HD) algorithm by incorporating a new criterion to better identify multieddy structures from satellite altimeter data. The criterion defines an aspect ratio to determine if eddies have vortex overlaps and, as such, result in a composite structure of multiple eddies (a.k.a. multieddy structures). Compared with two previous studies on observed eddy-eddy interactions in eddy mergers from altimeter data, the improved HD algorithm not only successfully captures multieddy structures but also shows how eddies interact and evolve, including merging, splitting, and partial vorticity exchange. Tests of the improved HD algorithm on a series of sea-level anomaly maps in the South China Sea (SCS) from 1993 to 2012 show that single eddies, in contrast to eddies with composite structures, appear more concentrated in northwest of the Luzon and southeast of Vietnam. Tracking dual-eddy structures reveals several processes of eddy interactions in the SCS. The study demonstrates the potential value of the new HD algorithm in helping scientists to investigate characteristics of eddy-eddy interactions from satellite observations.

关键词： Altimeter eddy-eddy interaction identification algorithm multieddy structure

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Closed-loop identification for aircraft flutter model parameters

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AIRCRAFT ENGINEERING AND AEROSPACE TECHNOLOGY 2022年第7期94卷 1117-1127页

作者： Wang Jianhong Jiangxi Univ Sci & Technol Sch Elect Engn & Automat Ganzhou Peoples R China

Purpose The purpose of this paper is to extend the authors' previous contributions on aircraft flutter model parameters identification. Because closed-loop condition is more widely used in today's practice, a closed-loop stochastic model of the aircraft flutter test is constructed to model the aircraft flutter process, whose input-output signals are all corrupted by the observed noises. Through using a rational transfer function, the equivalent property between the aircraft flutter model parameters and polynomial coefficients is established, and then the problem of aircraft flutter model parameters identification is turned to one closed-loop identification problem. An iterative identification algorithm is proposed to identify the unknown polynomial coefficients, being benefit for the latter flutter model parameter identification. Furthermore, as the closed-loop output corresponds to the flutter amplitude, so from the point of the minimization with respect to the variance of the closed-loop output, the optimal input signal and optimal feedback controller are all derived to achieve the zero flutter, respectively, for example, the optimal input spectrum and the detailed form for optimal feedback controller. Design/methodology/approach First, model parameter identification for aircraft flutter is reviewed as one problem of parameter identification and this aircraft flutter model corresponds to one closed-loop stochastic model, whose input signal and output are corrupted by external noises. Second, for aircraft flutter closed-loop statistical model with statistical noise, an iterative identification algorithm is proposed to identify the unknown model parameters. Third, from the point of minimizing with respect to the variance of the closed-loop output, the optimal input signal and optimal feedback controller are all derived to achieve the zero flutter, respectively, for example, the optimal input spectrum and the detailed form for optimal feedback controller. Findings Th

关键词： Aircraft flutter Model parameter identification algorithm Optimal input signal Statistical noise Optimal feedback controller

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Finding a fractional model from frequency and time responses

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COMMUNICATIONS IN NONLINEAR SCIENCE AND NUMERICAL SIMULATION 2010年第4期15卷 911-921页

作者： Valerio, Duarte da Costa, Jose Sa Univ Tecn Lisboa IST IDMEC Dept Mech Engn Lisbon Portugal

An existing method for identifying an integer model from frequency data, developed to be used when synthesising second-generation Crone controllers, is adapted to identify fractional order plants. The modification only allows models with poles but no zeros or zeros but no poles. Two application examples are given, one of them showing how the method can also be used when a time response, rather than a frequency response, is available. (C) 2009 Elsevier B.V. All rights reserved.

关键词： Fractional control identification algorithm Discrete-time systems Parameter identification Phase response

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An algorithm for identifying the initiation of synoptic-scale Rossby waves on potential vorticity waveguides

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QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY 2016年第695期142卷 889-900页

作者： Roethlisberger, Matthias Martius, Olivia Wernli, Heini Univ Bern Oeschger Ctr Climate Change Res Inst Geog Hallerstr 12 CH-3012 Bern Switzerland Univ Bern Mobiliar Lab Nat Risks Hallerstr 12 CH-3012 Bern Switzerland Swiss Fed Inst Technol Inst Atmospher & Climate Sci Zurich Switzerland

In this study, a novel method is presented that automatically identifies the initiation of synoptic-scale Rossby waves (RWIs) on potential vorticity (PV) waveguides. RWIs are identified based on geometry changes of the 2 PVU (where PVU is Potential Vorticity Units) contour on two isentropic levels (320 and 340 K). The 2 PVU contours are hereby regarded as proxies for the position and shape of the extratropical and subtropical waveguide, respectively. A RWI is recorded in a zonally aligned (i.e. wave-free) longitudinal contour segment if it becomes wavy over time and, additionally, the respective 2 PVU contour is wave-free upstream of the segment. To illustrate the potential of the method, three example RWIs are presented, which reveal distinct initiation mechanisms. In the first RWI, a large convective system triggers a Rossby wave on the extratropical waveguide. In the second case, the two waveguides are vertically co-aligned and a mesoscale lower-stratospheric high-PV anomaly leads to the initiation of a Rossby wave on both waveguides. The third case illustrates the interaction between the two waveguides. A breaking wave on the extratropical waveguide steers a lower-stratospheric high-PV anomaly into close proximity with the undisturbed subtropical waveguide and induces a wave on the latter. The method is applied to ERA-Interim data from 1979-2014, in order to produce a feature-based climatology of RWIs on the two waveguides in the Northern Hemisphere during winter. The three main regions where RWIs occur are the Northwestern Pacific, North America and the North Atlantic, as well as North Africa and the Middle East.

关键词： Rossby waves Rossby-wave initiation identification algorithm waveguide dynamics feature-based climatology potential vorticity

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identification of multivariable models of fast ferries

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EUROPEAN JOURNAL OF CONTROL 2004年第2期10卷 187-198页

作者： Aranda, J de la Cruz, JM Díaz, JM Univ Nacl Educ Distancia Fac Ciencias Dept Informat & Automat Madrid Spain Univ Complutense Madrid Fac Ciencias Fis Dept Arquitectura Comp & Automat Madrid Spain

This work presents the formal approach for identifying continuous transfer functions of the vertical dynamics of a high-speed ship as a nonlinear optimization problem with linear constraints. The proposed solution is described with a hybrid optimization method (genetic algorithm + nonlinear optimization algorithm with linear constraints from the Matlab toolbox).

关键词： identification algorithm marine systems optimization problem

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identification of AR time-series based on binary data

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IET SIGNAL PROCESSING 2020年第1期14卷 24-31页

作者： Auber, Romain Pouliquen, Mathieu Pigeon, Eric Gehan, Olivier M'Saad, Mohammed Chapon, Pierre Alexandre Moussay, Sebastien Normandie Univ UNICAEN ENSICAEN LACEA 7478 F-14050 Caen France Bodycap 3 Rue Dr Laennec F-14000 Caen France

In this study, the authors consider the identification of auto-regressive (AR) models for time-series from one-bit quantised observation sequences. The only available information is the fact that the samples of the time-series are lower or higher than a threshold of quantisation. This threshold may be different from zero. An identification algorithm is presented and analysed. A recursive formulation is proposed, an extension for the identification of a non-linear time-series is also proposed.

关键词： time series autoregressive processes quantisation (signal) AR time-series binary data autoregressive models one-bit quantised observation sequences quantisation identification algorithm nonlinear time-series

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Experimental investigation on the time-varying modal parameters of a trapezoidal plate in temperature-varying environments by subspace tracking-based method

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JOURNAL OF VIBRATION AND CONTROL 2015年第16期21卷 3305-3319页

作者： Yu, Kaiping Yang, Kai Bai, Yunhe Harbin Inst Technol Dept Astronaut Sci & Mech Harbin 150001 Peoples R China

Subspace-based methods for estimation of modal parameters are briefly reviewed in this study and a time-varying modal parameter identification algorithm, based on finite-data-window Projection Approximation Subspace Tracking, is presented to investigate the time-varying modal parameters of a trapezoidal titanium-alloy plate in temperature-varying environments. An experiment conducted on a steel beam with a removable mass is used to confirm the proposed method with a brief discussion on the factors of this method. Two groups of experiments are conducted to reveal the effects of varying temperature and heating speed on the natural frequencies of the plate, and the identified natural frequencies evidently show the effect of thermal stresses caused by temperature gradients in experiment.

关键词： Natural frequency temperature-varying environment identification algorithm modal parameter Projection Approximation Subspace Tracking (PAST)

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Nonlinear parametric identification based on the generalized probabilistic criteria

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JOURNAL OF AUTOMATION AND INFORMATION SCIENCES 2008年第5期40卷 52-60页

作者： Sokolov, S. V. Kucherenk, P. A. Rostov State Univ Railway Commun Rostov Na Donu Russia

The urgency of investigating the alternative (with respect to the traditional) methods of stochastic nonlinear parametric identification is shown. The solution of the problem on the parametric identification based on the generalized probabilistic criteria is proposed. The identification algorithm based on the minimum criterion of the estimation error probability is synthesized. The results of the experimental modeling which demonstrate an efficiency of the proposed method are presented.

关键词： parametric identification generalized probabilistic criteria estimation error probability identification algorithm

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Control-oriented thermal model and load identification for circulating cooling water system in precision process applications

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APPLIED THERMAL ENGINEERING 2024年第PartB期248卷

作者： Zeng, Zhibo Zhang, Wei Cao, Di Yu, Hangcheng Li, Xiaoping Huazhong Univ Sci & Technol Sch Mech Sci & Engn Wuhan 430074 Peoples R China

With the increasing precision in machining and measurement, there is a growing demand for improved temperature stability in cooling water systems used in industrial processes. Accurate thermal models and load states are essential for developing efficient controllers to enhance temperature performance. This paper focuses on the development of thermal models for various components of circulating water systems in precision water-cooling processes. It presents a control-oriented thermal model framework that segregates the water circulation cycles and defines system inputs and processes. A novel identification algorithm is proposed to address thermal inertia and cyclic nonlinearity by extracting the cyclic period and cycle change rate. The algorithm can simultaneously estimate the state-space model and unmeasurable load disturbances. A validation experimental setup was constructed, and the results demonstrate that, for different flow scenarios, the estimated load and thermal model parameters align well, with correlations exceeding 0.85 and error ratios close to 10%. Additionally, the circulating water output temperature can be accurately predicted. The fitting degrees surpass 84% within five cycles, with correlations exceeding 0.97 and error standard deviations below 0.22 degrees C.

关键词： Circulating cooling water Cyclic period identification algorithm Load estimation Thermal model

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