Chikit Au¹, Yiyu Cai², Jianmin Zheng³, Tony Woo⁴

CMES-Computer Modeling in Engineering & Sciences, Vol.68, No.3, pp. 221-238, 2010, DOI:10.3970/cmes.2010.068.221

Abstract A protein model (such as a ribbon model) can be created from the atomic coordinates in the protein data base files. These coordinates are obtained by X-ray crystallography or NMR spectroscopy with the protein arbitrarily oriented. As such, identifying or comparing a novel structure with a known item using protein model in the protein data base can be a timely process since a large number of transformations may be involved. The identification efficiency will be improved if the protein models are uniformly oriented. This paper presents an approach to orient a protein model to generate More >

Chein-Shan Liu¹, Satya N. Atluri²

CMES-Computer Modeling in Engineering & Sciences, Vol.64, No.3, pp. 299-326, 2010, DOI:10.3970/cmes.2010.064.299

Abstract We solve the Calderón inverse conductivity problem [Calderón (1980, 2006)], for an elliptic type equation in a rectangular plane domain, to recover an unknown conductivity function inside the domain, from the over-specified Cauchy data on the bottom of the rectangle. The Calderón inverse problem exhibitsthree-fold simultaneous difficulties: ill-posedness of the inverse Cauchy problem, ill-posedness of the parameter identification, and no information inside the domain being available on the impedance function. In order to solve this problem, we discretize the whole domain into many sub-domains of finite strips, each with a small height. Thus the Calderón… More >

Jie Qu^1,2, Bingye Xu³, Quanlin Jin⁴

CMC-Computers, Materials & Continua, Vol.20, No.2, pp. 119-158, 2010, DOI:10.3970/cmc.2010.020.119

Abstract Large and complex macro-micro coupled constitutive models, which describe metal flow and microstructure evolution during metal forming, are sometimes overparameterized with respect to given sets of experimental datum. This results in poorly identifiable or non-identifiable model parameters. In this paper, a systemic parameter identification method for the large macro-micro coupled constitutive models is proposed. This method is based on the global and local identifiability analysis, in which two identifiability measures are adopted. The first measure accounts for the sensitivity of model results with respect to single parameters, and the second measure accounts for the degree… More >

S.Mohanty¹, A. Chattopadhyay², J. Wei³, P. Peralta⁴

Structural Durability & Health Monitoring, Vol.5, No.3, pp. 227-250, 2009, DOI:10.3970/sdhm.2009.005.227

Abstract This paper proposes unsupervised system identification based methods to estimate time-series fatigue damage states in real-time. Ultrasound broadband input is used for active damage interrogation. Novel damage index estimation techniques based on dual sensor signals are proposed. The dual sensor configuration is used to remove electrical noise, as well as to improve spatial resolution in damage state estimation. The scalar damage index at any particular damage condition is evaluated using nonparametric system identification techniques, which includes an empirical transfer function estimation approach and a correlation analysis approach. In addition, the effectiveness of two sensor configurations More >

V. Srinivas¹, Saptarshi Sasmal¹, K. Ramanjaneyulu²

Structural Durability & Health Monitoring, Vol.5, No.2, pp. 133-160, 2009, DOI:10.3970/sdhm.2009.005.133

Abstract Many advances have taken place in the area of structural damage detection and localization using several approaches. Availability of cost-effective computing memory and speed, improvement in sensor technology including remotely monitored sensors, advancements in the finite element method, adaptation of modal testing and development of non-linear system identification methods bring out immense technical advancements that have contributed to the advancement of modal-based damage detection methods. Advances in modal-based damage detection methods over the last 20-30 years have produced new techniques for examining vibration data for identification of structural damage. In this paper, studies carried out… More >

N.H.M. Kamrujjaman Serker¹, Zhishen Wu

Structural Durability & Health Monitoring, Vol.5, No.2, pp. 87-108, 2009, DOI:10.3970/sdhm.2009.005.087

Abstract This paper presents the study on the temperature sensitivity of some vibration-based damage identification techniques. With the help of a simple supported beam with different damage levels, reliability of these techniques for damage identification in a changing environmental temperature condition was investigated. The temperature effect was considered as the change in modulus of elasticity of the material. The techniques evaluated herein are based on measured modal parameters which use only few mode shapes and/or modal frequencies of the structure that can easily be obtained by dynamic tests. The effect of temperature on identification of different More >

Deyi Zhang¹, Yuequan Bao, Feng Zhou, Hui Li

The International Conference on Computational & Experimental Engineering and Sciences, Vol.12, No.2, pp. 65-72, 2009, DOI:10.3970/icces.2009.012.065

Abstract Modal identification is essential in structural health monitoring (SHM) because that the modal parameters are often used for model updating and damage detection. However, in practical situations, the variation of environmental conditions (e.g. temperature, temperature gradients, humidity, etc.) will impede the reliability of modal identification. In this paper, firstly, the relation of frequency change and variation of environment temperature of space structure is investigated. Then, a structural state assessment method by combing autoregressive moving average (ARMA) and PCA is proposed. The acceleration data from China National Aquatics Center is employed as an example. The results More >

G.S. Li¹, D. Yao², Y.Z. Wang³, H.Y. Jiang²

CMES-Computer Modeling in Engineering & Sciences, Vol.51, No.1, pp. 53-72, 2009, DOI:10.3970/cmes.2009.051.053

Abstract In this paper, an undisturbed soil-column infiltrating experiment is investigated, and a mathematical model describing multi-components solutes transport behaviors in the column is put forward by combing hydro-chemical analysis with advection dispersion mechanisms, which is a group of advection-dispersion-reaction partial differential equations. Since the model involving six reaction coefficients which can not be obtained directly, an optimal perturbation regularization algorithm of determining these parameters is performed, and numerical simulations under different conditions are carried out. Furthermore, the inversion algorithm is applied to solve the real inverse problem by utilizing the measured breakthrough data. The reconstruction More >

M.Galli , M.L.Oyen¹

CMES-Computer Modeling in Engineering & Sciences, Vol.48, No.3, pp. 241-270, 2009, DOI:10.3970/cmes.2009.048.241

Abstract A novel approach is presented for the identification of constitutive parameters of linear poroelastic materials from indentation tests. Load-controlled spherical indentation with a ramp-hold creep profile is considered. The identification approach is based on the normalization of the time-displacement indentation response, in analogy to the well-known one-dimensional consolidation problem. The identification algorithm consists of two nested optimization routines, one in the time-displacement domain and the other in a normalized domain. The procedure is validated by identifying poroelastic parameters from the displacement-time outputs of finite element simulations; the new identification scheme proves both quantitatively reliable and More >

Dong Wei¹, Yinghua Liu^1,2, Zhihai Xiang¹

CMES-Computer Modeling in Engineering & Sciences, Vol.46, No.1, pp. 77-106, 2009, DOI:10.3970/cmes.2009.046.077

Abstract Taking advantage of the parameter identification, a new numerical method is developed in this paper to estimate the maximal temperature gradients reached in fire-damaged concrete structures. This method can avoid the hypotheses of temperature-time curve and fire duration usually made in conventional numerical methods, availably evaluate the depth and degree of fire damage of concrete structures and consider the effects of localized fire. A material model taking into account the properties of fire-damaged concrete is firstly proposed in the present research. The least-squares estimation and the Gauss-Newton method are used to identify the material parameters… More >