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Viscoelastic behavior on composite beam using nonlinear creep model

STEEL AND COMPOSITE STRUCTURES 2007年第5期7卷 355-376页

作者： Jung, Sung-Yeop Nam-Il Kim Shin, Dong Ku Pyunghwa Inst Construct Technol Anyang 431810 Kyonggi Do South Korea Myongji Univ Dept Civil & Environm Engn Yongin 449728 Kyonggi Do South Korea

The purpose of this study is to predict and investigate the time-dependent creep behavior of composite materials. For this, firstly the evaluation method for the modulus of elasticity of whole fiber and matrix is presented from the limited information on fiber volume fraction using the singular value decomposition method. Then, the effects of fiber volume fraction on modulus of elasticity of GFRP are verified. Also, as a creep model, the nonlinear curve fitting method based on the marquardt algorithm is proposed. Using the existing Findley's power creep model and the proposed creep model, the effect of fiber volume fraction on the nonlinear creep behavior of composite materials is verified. Then, for the time-dependent analysis of a composite material subjected to uniaxial tension and simple shear loadings, a user-provided subroutine UMAT is developed to run within ABAQUS. Finally, the creep behavior of center loaded beam structure is investigated using the Hermitian beam elements with shear deformation effect and with time- dependent elastic and shear moduli.

关键词： composite beam creep fiber volume fraction curve fitting method marquardt algorithm

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Estimation of Langmuir and Sips Models Adsorption Parameters for NaX and NaY FAU Zeolites

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JOURNAL OF CHEMICAL AND ENGINEERING DATA 2015年第10期60卷 2858-2868页

作者： Zito, Pasquale F. Caravella, Alessio Brunetti, Adele Drioli, Enrico Barbieri, Giuseppe Univ Calabria Dept Environm & Chem Engn I-87036 Arcavacata Di Rende CS Italy Inst Membrane Technol ITM CNR Natl Res Council I-87036 Arcavacata Di Rende CS Italy

The single-gas adsorption properties of various species (H-2, CH4, CO2 CO, H2O) involved in quite important industrial processes, such as methane steam reforming and water gas shift reaction, are evaluated for Faujasite NaX and NaY zeolites. To carry out such an investigation, a multivariate regression analysis (using Levenberg-marquardt algorithm) is adopted, fitting experimental adsorption isotherms from the literature with the Langmuir and Sips models. A number of experimental isotherms is used to enlarge as much as possible the Validity range in terms of temperature and pressure. The evaluated parameters are compared with those available in the open literature, in order to provide a further confirmation of the results of the present work. Such a comparison is required to extend the literature information and, where necessary, to cover the current lack of adsorption data for the considered zeolite. The chosen functionality of the adsorption parameters with temperature and pressure should be useful in a wide range of applications.

关键词： ZEOLITES -- Absorption & adsorption LANGMUIR isotherms SODIUM compounds WATER gas shift reactions METHANE marquardt algorithm

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COMPARISON OF 4 ELEMENTAL MASS-BALANCE METHODS FOR CLAY MINERAL QUANTIFICATION

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CLAYS AND CLAY MINERALS 1994年第4期42卷 437-443页

作者： KOLKA, RK LAIRD, DA NATER, EA USDA ARS NATL SOIL TILTH LABAMESIA 50011

The quantification of the relative mineralogical composition of clay mixtures by powder X-ray diffraction or chemical mass balance methods has been severely hampered by a lack of representative standards. The recent development of elemental mass balance models that do not require standards for all minerals in the mixture may help circumvent this problem. These methods, which are based on the numerical optimization of systems of non-linear equations using the marquardt algorithm, show promise for mineral quantification. The objective of this study is to make a preliminary assessment of the accuracy of these methods and to compare them to linear models that require standards for all mineral phases. Methods 1 and 2 are based on weighted average solutions to simultaneous linear equations solved for single samples with known standards. Solutions were achieved by a matrix decomposition algorithm and the marquardt algorithm, respectively. Methods 3 and 4 are based on a set of simultaneous non-linear equations with reduced non-linearity solved by least squares optimization based on the marquardt algorithm for multiple samples. Illite and halloysite compositions were fixed in Method 3, only the halloysite composition was fixed in Method 4. All models yielded relative weight fractions of the three mineral components;additionally, Methods 3 and 4 yielded compositions of smectite, and smectite and illite, respectively. Ten clay mixtures with varying proportions of the <0.2 mu m size fraction of three different reference clays (Wyoming bentonite, Fithian illite, and New Bedford halloysite) were prepared gravimetrically and analyzed by inductively coupled plasma-atomic emission spectroscopy. Accuracy of the four methods was evaluated by comparing the known mineralogical compositions of the mixtures with those predicted by the models. Relative errors of 5 and 10% (randomly +/-) were imposed on the elemental composition of the smectite standard to simulate errors due to lack of goo

关键词： ELEMENTAL MASS BALANCE marquardt algorithm NONLINEAR MODELS NUMERICAL OPTIMIZATION QUANTIFICATION

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Design and Implementation of Recursive Model Predictive Control for Permanent Magnet Synchronous Motor Drives

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MATHEMATICAL PROBLEMS IN ENGINEERING 2015年第1期2015卷 1-10页

作者： Wu, Xuan Wang, Hui Yuan, Xiaofang Huang, Shoudao Luo, Derong Hunan Univ Natl Engn Technol Res Ctr Elect Power Convers & C Changsha 410082 Hunan Peoples R China

In order to control the permanent-magnet synchronous motor system (PMSM) with different disturbances and nonlinearity, an improved current control algorithm for the PMSM systems using recursive model predictive control (RMPC) is developed in this paper. As the conventional MPC has to be computed online, its iterative computational procedure needs long computing time. To enhance computational speed, a recursive method based on recursive Levenberg-marquardt algorithm (RLMA) and iterative learning control (ILC) is introduced to solve the learning issue in MPC. RMPC is able to significantly decrease the computation cost of traditional MPC in the PMSM system. The effectiveness of the proposed algorithm has been verified by simulation and experimental results.

关键词： PREDICTIVE control PERMANENT magnet motors SYNCHRONOUS electric motors MOTOR drives (Electric motors) marquardt algorithm NONLINEAR theories

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Inclusional complex study between 6-p-toluidinylnaphthalene-2-sulfonate and 2-hydroxypropyl-beta-cyclodextrin

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JOURNAL OF BIOCHEMICAL AND BIOPHYSICAL METHODS 2002年第2期52卷 121-134页

作者： Dotsikas, Y Loukas, YL Univ Athens Sch Pharm Dept Pharmaceut Chem Athens 15771 Greece

6-p-Toluidinylnaphthalene-2-sulfonate (TNS) is used as a fluorescent probe for exploring hydrophobic regions of several biological substances, such as proteins, and studying solution state folding behaviour. The current study examines the complexation of TNS with 2-hydroxypropyl-beta-cyclodextrin (HPbetaCD) in aqueous solution, mainly by ultraviolet spectrophotometry using various concentrations of HPbetaCD. The structure of HPbetaCD was confirmed by using positive-ion electrospray ionization (ESI+) mass spectrometry. The complex was examined for its stoichiometry applying the continuous variation (Job plot) method. Also, the kinetics of the complex formation was monitored and the determination of the stability constant was calculated. For this purpose, the spectrophotometric properties of TNS were observed in the presence of increasing concentrations of HPbetaCD applying the transformed Benesi-Hildebrand linear model as well as a nonlinear one. The results suggest that TNS forms a stable complex of 1:1 molar ratio, at least at the examined concentrations. Furthermore, from the measurements of H-1 nuclear magnetic resonance (H-1 NMR) spectra, interactions between protons of TNS with HPbetaCD were determined. (C) 2002 Elsevier Science B.V. All rights reserved.

关键词： 2-hydroxypropyl-beta-cyclodextrin 6-p-toluidinylnaphthalene-2-sulfonate job plot marquardt algorithm electrospray mass spectrometry

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Time domain diffusion parameters identification of electrochemical impedance models using fractional order system

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IFAC-PapersOnLine 2018年第15期51卷 377-382页

作者： Eddine, Achraf Nasser Huard, Benoît Gabano, Jean-Denis Poinot, Thierry Thomas, Anthony Martemianov, Serguei Université de Poitiers LIAS 2 rue Pierre Brousse TSA 41105 cedex 9 Poitiers86073 France Université de Poitiers Institut Pprime 2 rue Pierre Brousse TSA 41105 cedex 9 Poitiers86073 France

In this paper, identification of the diffusion impedance parameters of an electrochemical cell in time domain is presented. As Electrochemical Impedance Spectroscopy (EIS) requires long time to obtain experimental data for low frequencies, a method using chronopotentiometric experiments is studied in order to reach more quickly diffusion parameters. The electrochemical cell is modeled using an equivalent electrical circuit describing separately the charge transfer and the diffusion phenomena. The electrochemical model provides then a transfer function whose parameters can be identified only in the frequency domain. Thus, thanks to a fractional operator approximation, a half order integrator is able to perform simulations in the time domain. Therefore, a fractional model is proposed in order to identify the slow dynamics due to diffusion thanks to the Levenberg-marquardt algorithm. Experimental results obtained from an electrochemical test-bench including Ferri-Ferro solution demonstrate the interest of fractional modeling. Diffusion parameters are identified in the time domain and cross-validation in the frequency domain using EIS measurements demonstrates the relevance of the proposed method. © 2018

关键词： Time domain analysis Charge transfer Diffusion Electrochemical cells Electrochemical impedance spectroscopy Frequency domain analysis Parameter estimation Solar cells Spectroscopy State space methods Chronopotentiometry Electrochemical impedance Electrochemical modeling Equivalent electrical circuits Fractional model Identification algorithms Levenberg marquardt algorithm State space models

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On Arbitrary Fractional System Identification in Frequency Domain

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IFAC-PapersOnLine 2015年第28期48卷 1421-1426页

作者： Li, Dazi liu, Lang Song, Tianheng shen, Dong Institute of Automation Beijing University of Chemical Technology Beijing100029 China

An identification algorithm for arbitrary order fractional system is proposed with frequency domain information. According to the frequency domain characteristics of fractional differential operator, the parameters estimation of the arbitrary order fractional system is transformed into a nonlinear equations problem. The variable damping least square method is applied to solve this nonlinear problem. In order to improve the efficiency of the parameters identification, a method to reduce the number of unknown parameters is also investigated. Numerical results illustrate the effectiveness of the proposed approach. © 2015

关键词： Frequency domain analysis Frequency estimation Least squares approximations Mathematical operators Nonlinear equations Religious buildings Arbitrary order Fractional differential operators Fractional systems Frequency domains Identification algorithms Levenberg marquardt algorithm Parameters estimation Parameters identification

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Bayesian smoothing in the estimation of the pair potential function of Gibbs point processes

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BERNOULLI 1999年第6期5卷 1119-1136页

作者： Heikkinen, J Penttinen, A Finnish Forestry Res Inst FIN-00170 Helsinki Finland Univ Jyvaskyla Dept Stat FIN-40351 Jyvaskyla Finland

A flexible Bayesian method is suggested for pair potential estimation with a high-dimensional parameter space. The method is based on a Bayesian smoothing technique, commonly applied in statistical image analysis. For the calculation of the posterior mode estimator a new Monte Carlo algorithm is developed. The method is illustrated through examples with both real and simulated data, and its extension into truly nonparametric pair potential estimation is discussed.

关键词： Bayesian smoothing Gibbs processes posterior mode estimator Markov chain Monte Carlo methods marquardt algorithm pair potential function

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Heat equation parameter estimation based on the POD-Galerkin approach

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IFAC-PapersOnLine 2018年第15期51卷 245-250页

作者： Pham, Duc-Cuong Mercère, Guillaume Ouvrard, Régis Poinot, Thierry Université de Poitiers LIAS 2 rue Pierre Brousse TSA 41105 Cedex 9 Poitiers86073 France

The proper orthogonal decomposition (POD), a mathematical procedure initially developed to determine low-dimensional approximated descriptions of high-dimensional functions, has already proved its efficiency for model reduction of linear and non-linear systems. In this paper, the POD and the Galerkin projection methods are combined to estimate the thermal diffusivity parameter of a wall, the behavior of which is assumed to be modeled by the famous heat partial differential equation (PDE). According to this approach, empirical orthogonal functions are first extracted from the POD, then used by the Galerkin method to transform the initial PDE into a set of ordinary differential equations (ODEs). These ODEs explicitly contain the parameter to be identified which is estimated in this contribution by using the Levenberg-marquardt algorithm. Simulation results are provided to illustrate the effectiveness of this multi-step approach. © 2018

关键词： Parameter estimation Galerkin methods Heat transfer Identification (control systems) Linear systems Ordinary differential equations Orthogonal functions Partial differential equations Principal component analysis Empirical Orthogonal Function Galerkin projections Heat equation Levenberg marquardt algorithm Mathematical procedures Multi step approaches Partial differential equations (PDE) Proper orthogonal decompositions

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Frequential identification of an electrochemical cell impedance using fractional modeling

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IFAC-PapersOnLine 2018年第15期51卷 802-807页

作者： Nasser Eddine, Achraf Huard, Benoît Gabano, Jean-Denis Poinot, Thierry Thomas, Anthony Martemianov, Serguei Université de Poitiers LIAS 2 rue Pierre Brousse TSA 41105 cedex 9 Poitiers86073 France Université de Poitiers Institut Pprime 2 rue Pierre Brousse TSA 41105 cedex 9 Poitiers86073 France

Electrochemical Impedance Spectroscopic (EIS) represents an important technique to characterize the impedance of electrochemical systems. The internal impedance phenomena can be modeled using Electrical Equivalent Circuit. Fractional operator is used to characterize the charge transfer and the diffusion phenomena. This may be attractive due to the ability of fractional systems to be simulated either in frequency or time domain. The impedance model using fractional systems is represented by a transfer function that is identified using Levenberg-marquardt algorithm. The fractional model identification is validated on an experimental test-bench using two platinum electrodes immersed into Ferri-Ferro solution. Results indicate the ability of fractional system to identify properly the different impedance parameters. In order to decrease the long experiment time of EIS, minimization of the low frequency measurement points is performed and results show the ability of fractional systems to identify EIS data. © 2018

关键词： Equivalent circuits Charge transfer Electrodes Parameter estimation Spectroscopy Electrical equivalent circuit Fractional model identification Fractional systems Identification algorithms Impedance parameters Levenberg marquardt algorithm Low frequency measurements Nernst diffusion

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