Relevant bibliographies by topics / Ibrahim time domain

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  1. Journal articles
  2. Dissertations / Theses
  3. Book chapters
  4. Conference papers

Academic literature on the topic 'Ibrahim time domain'

Author: Grafiati
Published: 4 June 2021
Last updated: 17 February 2022

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Journal articles on the topic "Ibrahim time domain"

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Brincker, Rune, Peter Olsen, Sandro Amador, Martin Juul, Abdollah Malekjafarian, and Mohammad Ashory. "Modal participation in multiple input Ibrahim time domain identification." Mathematics and Mechanics of Solids 24, no. 1 (October 14, 2017): 168–80. http://dx.doi.org/10.1177/1081286517733034.

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The Ibrahim time domain (ITD) identification technique was one of the first techniques formulated for multiple output modal analysis based on impulse response functions or general free decays. However, the technique has not been used much in recent decades due to the fact that the technique was originally formulated for single input systems that suffer from well-known problems in case of closely spaced modes. In this paper, a known, but more modern formulation of the ITD technique is discussed. In this formulation the technique becomes multiple input by adding some Toeplitz matrices over a set of free decays. It is shown that a special participation matrix can be defined that cancels out whenever the system matrix is estimated. The participation matrix becomes rank deficient if a mode is missing in the responses, but if any mode is present in one of the considered free decays, the participation matrix has full rank. This secures that all modes will be contained in the estimated system matrix. Finally, it is discussed how correlation functions estimated from the operational responses of structures can be used as free decays for the multiple-input ITD formulation, and the estimation errors of the identification technique are investigated in a simulation study with closely spaced modes. The simulation study shows that the multiple-input formulation provides estimates with significantly smaller errors on both mode shape and natural frequency estimates.
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Mohanty, P., and D. J. Rixen. "A modified Ibrahim time domain algorithm for operational modal analysis including harmonic excitation." Journal of Sound and Vibration 275, no. 1-2 (August 2004): 375–90. http://dx.doi.org/10.1016/j.jsv.2003.06.030.

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Leuridan, J. M., D. L. Brown, and R. J. Allemang. "Time Domain Parameter Identification Methods for Linear Modal Analysis: A Unifying Approach." Journal of Vibration and Acoustics 108, no. 1 (January 1, 1986): 1–8. http://dx.doi.org/10.1115/1.3269298.

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The paper describes a method that uses a multivariate model in the form of a nonhomogeneous finite difference equation to identify modal parameters of a mechanical structure. The modal parameters of this equation are estimable using a model that involves multiple input, multiple output vibration data. Thus, improved global estimates of modal parameters can be obtained, including the identification of highly coupled and pseudo-repeated modes of vibration. When the data are in the form of impulse or free decay responses, then the parameters of the homogeneous part of the equation can be estimated separately, and the method is then related to the Least Squares Complex Exponential method, the Polyreference Time Domain method and the Ibrahim Time Domain method.
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Zhang, Peng, Xiaoru Wang, Xiangchao Wang, and James S. Thorp. "Synchronized measurement based estimation of inter-area electromechanical modes using the Ibrahim time domain method." Electric Power Systems Research 111 (June 2014): 85–95. http://dx.doi.org/10.1016/j.epsr.2014.02.005.

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Kashani, H., and A. S. Nobari. "Structural Nonlinearity Identification Using Perturbed Eigen Problem and ITD Modal Analysis Method." Applied Mechanics and Materials 232 (November 2012): 949–54. http://dx.doi.org/10.4028/www.scientific.net/amm.232.949.

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Identification of nonlinear behavior in structural dynamics has been considered here, in this paper. Time domain output data of system are directly used to identify system through Ibrahim Time Domain (ITD) modal analysis method and perturbed eigen problem. Cubic stiffness and Jenkins element, as case studies, are employed to qualify the identification method. Results are compared with Harmonic Balance (HB) estimation of nonlinear dynamic stiffness. Results of ITD based identification are in good agreement with the HB estimation, for stiffness parts of nonlinear dynamic stiffness but for damping parts of nonlinear dynamic stiffness, method needs some additional improvements which are under investigation.
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Anuar, M. A., Liyana Roslan, and A. A. Mat Isa. "Dynamic Parameter Identification Using Ambient Response Analysis and Ibrahim Time Domain Approach: A Case Study on a Steel Plate Structure." Applied Mechanics and Materials 110-116 (October 2011): 2395–99. http://dx.doi.org/10.4028/www.scientific.net/amm.110-116.2395.

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Since the level of vibration always depends on the natural frequencies of the system, it is important to know the modal parameters of such system to control failure and provide prevention actions. However, for many mechanical engineering machines or structures, there is a demand and necessity to determine real-life modal parameters using actual operating condition. This type of testing condition cannot be done in lab environment because most of the mechanical structure is big in size and heavy. Thus, the purpose of this paper is to study the natural frequencies of a steel plate by using Operational Modal Analysis (OMA) and Ibrahim Time Domain (ITD). Comparison of results between both approaches will be shown.
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Jiang, Hao, Guang Wei Meng, and Bao Wei Xiong. "Modal Parameters Identification of Bridge Structure Based on Excitation of Wind Load." Applied Mechanics and Materials 405-408 (September 2013): 1660–63. http://dx.doi.org/10.4028/www.scientific.net/amm.405-408.1660.

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Applying the combination of the natural excitation technique and the Eigen system realization algorithm, a finite element numerical simulation was performed for the dynamic behavior identification of a pre-stressed concrete continuous beam bridge under simulating wind load excitation. The results were validated comparatively using the combined algorithm of random decrement technique and Ibrahim time domain technique as well as the finite element modal analysis. The simulation results show that the wind load as the most common environmental excitation can be used effectively to identify the modal parameters of the concrete bridge.
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Sun, Jinghai, Hui Li, and Wenbai Zhu. "Practical Damping Identification of FAST Cable Suspension." Advances in Mechanical Engineering 6 (January 1, 2014): 813752. http://dx.doi.org/10.1155/2014/813752.

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FAST focus cabin is suspended and driven by 6 parallel large span cables. Low stiffness of cables makes the cabin sensitive to disturbance and difficult to control. Structural damping then becomes a key factor that can improve control ability. Therefore, a reasonable damping estimation is important for system design. In this paper, a practical damping identification method is developed based on Ibrahim-time-domain algorithm. The method shows satisfied performance on accuracy and reliability in simulation test and is utilized in vibration experiments to identify damping ratios of both single cable model and FAST 3 m scale cable suspension model. Finally, a preliminary analysis of the damping properties is given out based on the results of identification.
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Nangolo, Fillemon Nduvu, and František Klimenda. "Modal Parameter Analysis for Underdamped Mechanical Systems." Applied Mechanics and Materials 732 (February 2015): 247–52. http://dx.doi.org/10.4028/www.scientific.net/amm.732.247.

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There are many ways to model and to analyze discrete event systems. In general these systems lead to a non-linear characteristic equation description in linear algebra. This paper presents an analytical method for solving the characteristic equation of higher order, which arise when solving ordinary differential equations of motion of rigid body systems with 2 ≤ p° ≤ 10 degrees of freedom. The objective of this work was to express the characteristic equation in the form of product quadratic polynomial, from which the modal components could be found. To validate the model, the modal parameters extraction technique – Ibrahim Time Domain (ITD) – was used to extract modal parameters from artificial data developed in MATLAB environment. The extracted modal components were compared to those obtained from the analytical model.
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Zhang, Zhi Ying, Qing Sun, and Zheng Yang. "An Identification Method for Damping Ratio of In Situ Building." Advanced Materials Research 446-449 (January 2012): 556–60. http://dx.doi.org/10.4028/www.scientific.net/amr.446-449.556.

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Damping evaluation is of great importance in predicting the dynamic response of systems. To get the accurate damping ratios of a system, many identification methods have been proposed and developed. But only few of them achieved accurate results for in-situ buildings due to the fact that the responses are significantly influenced by noise. This paper proposes a new method to accurately identify the damping ratios of in-situ buildings. The method is based on ambient excitation technique which requires no artificial excitation applied to SSI system and to measure output-only. The damping ratio identification is then performed by combining the improved random decrement method and Ibrahim time domain method. To demonstrate the validity of the proposed approach, a case study is performed and the results are compared with the conventional peak-peaking method results. The results show the proposed method can effectively identify the modal parameter of either frequencies or damping ratios of in-situ buildings subjected to ambient excitation.
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Dissertations / Theses on the topic "Ibrahim time domain"

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Paziani, Fabricio Tadeu. "Identificação de parâmetros modais no domínio do tempo: método ITD." Universidade de São Paulo, 2002. http://www.teses.usp.br/teses/disponiveis/18/18135/tde-18092015-164805/.

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O método de Ibrahim no Domínio do Tempo (ITD) é considerado um dos métodos clássicos de identificação de parâmetros modais de estruturas. As maiores vantagens da sua aplicação residem na identificação de modos muito próximos com boa precisão, em uma faixa relativamente larga de freqüências, além do número reduzido de equipamentos requeridos para a realização de ensaios experimentais. Neste trabalho foi realizada uma aplicação do método ITD no processo de identificação das freqüências naturais, dos fatores de amortecimento e dos modos de vibrar de uma placa quadrada de alumínio, engastada em um dos lados e livre nos demais. Este modelo experimental apresenta alta densidade modal e a análise foi realizada em uma faixa de freqüências de 0 a 1600 Hz através de um ensaio de impacto. Para produzir um conjunto consistente de resultados é necessário utilizar um modelo sobredeterminado para o sistema em estudo. O resultado desta análise, porém, apresenta modos computacionais que devem ser eliminados. Para tanto, foram utilizados dois índices de confiança para qualificar os resultados, sendo estes o Fator de Confiança Modal (MCF) e a Colinearidade de Fase Modal Ponderada (MPCW). Os modos que apresentaram melhores índices de confiança são considerados o resultado final do processo de identificação.
The Ibrahim Time Domain (ITD) method is considered one of the classical modal parameter identification techniques. The greatest advantages of the ITD application consist of the precise identification of closely spaced modes within a wide range of frequencies and the small amount of equipment required to accomplish experimental testing. In this work, the ITD method was applied in the process of identification of natural frequencies, damping factors and mode shapes of a cantilever aluminium plate. High modal density was detected on the experimental model and the analysis was performed on a frequency range from 0 to 1600 Hz by means of impulse testing. However, an oversized model of the test structure must be used, so that a consistent set of results can be achieved. The results, nevertheless, present computational modes that must be removed from the model. Two confidence factors were used to qualify the results, namely the Modal Confidence Factor (MCF) and the Modal Phase Collinearity - Weighted (MPCW). The modes that presented higher confidence factor values were considered as the final result of the identification process.
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Jakuš, Matúš. "Tvorba a aplikace algoritmů pro odhad modálních parametrů v časové oblasti a studie jejich citlivosti na okrajové podmínky." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2016. http://www.nusl.cz/ntk/nusl-241728.

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Cieľom tejto diplomovej práce je predstavenie Experimentálnej modálnej analýzy a štúdium a použitie algoritmov pre výpočet modálnych parametrov z odmeraných vibrácií pri Experimentálnej modálnej analýze. Bodom záujmu sú predovšetkým algoritmy, pracujúce s odmeranými dátami v časovej oblasti. Diplomová práca sa zaoberá programovaním algoritmu ITD a jeho implementáciou pre Experimentálnu modálnu analýzu. Ďaľšou časťou práce je štúdium citlivosti algoritmu na okrajové podmienky meranej sústavy pri výpočte modálnych parametrov a štúdium možnosti využitia algoritmu pri Operačnej modálnej analýze.
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YANG, YUAN-CHENG, and 楊淵成. "Determination of displacement bound of beam using Ibrahim Time Domain Method." Thesis, 1989. http://ndltd.ncl.edu.tw/handle/97103634922355812602.

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CHEN, YAN-RONG, and 陳彥榕. "Determination of the buckling load of beam structure by Ibrahim time domain method." Thesis, 1988. http://ndltd.ncl.edu.tw/handle/86115315163909999922.

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Yu-JheLin and 林宇哲. "Identification of Modal Parameters of Systems with Modal Interference by Ibrahim Time Domain Method." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/zy6zdg.

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碩士
國立成功大學
航空太空工程學系
104
Modal interferences often cause problems on identifiability and affect the accuracy of system identification during the process of modal parameter identification. Major causes of modal interferences include close frequencies, high damping ratios, non-proportional damping…etc. This thesis will investigate modal-parameter identification in time domain, by proposes a method of using the technique of channel-expansion in Ibrahim time domain method to improve identification accuracy.In general, selecting the order of system before using Ibrahim time domain method is important. This thesis proposes Singular Value Decomposition instead of the Method of Least Squares to solve the matrix of system and at the same time evaluate the order of system to avoid the phenomenon of omitted modes. In addition, this thesis proposes the use of the phase angle diagram of frequency response function in conjunction with the amplitude diagram. So that it is easier to distinguish the modes which are influenced by modal interference. SUMMARY Modal interferences often cause problems on identifiability and affect the accuracy of system identification during the process of modal parameter identification. Major causes of modal interferences include close frequencies, high damping ratios, non-proportional damping…etc. This thesis will investigate modal-parameter identification in time domain, by proposes a method of using the technique of channel-expansion in Ibrahim time domain method to improve identification accuracy. In general, selecting the order of system before using Ibrahim time domain method is important. This thesis proposes Singular Value Decomposition instead of the Method of Least Squares to solve the matrix of system and at the same time evaluate the order of system to avoid the phenomenon of omitted modes. In addition, this thesis proposes the use of the phase angle diagram of frequency response function in conjunction with the amplitude diagram. So that it is easier to distinguish the modes which are influenced by modal interference.
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Book chapters on the topic "Ibrahim time domain"

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Olsen, Peter, and Rune Brincker. "Using Random Response Input in Ibrahim Time Domain." In Special Topics in Structural Dynamics, Volume 6, 281–87. New York, NY: Springer New York, 2013. http://dx.doi.org/10.1007/978-1-4614-6546-1_29.

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Lin, Chang-Sheng, and Tse-Chuan Tseng. "Modal Identification of Over-Damped Structural Systems Using Extended Ibrahim Time-Domain Method." In Experimental and Applied Mechanics, Volume 6, 143–48. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-06989-0_19.

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Lee, Jongsuh, Sunghwan Kim, Daesung Kim, and Semyung Wang. "Experimental Modal Analysis (EMA) Using Ibrahim Time Domain (ITD) Method and Winer Filter." In Conference Proceedings of the Society for Experimental Mechanics Series, 253–60. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4419-9299-4_21.

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Malekjafarian, A., R. Brincker, M. R. Ashory, and M. M. Khatibi. "Modified Ibrahim Time Domain Method for Identification of Closely Spaced Modes: Experimental Results." In Topics on the Dynamics of Civil Structures, Volume 1, 443–49. New York, NY: Springer New York, 2012. http://dx.doi.org/10.1007/978-1-4614-2413-0_44.

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Conference papers on the topic "Ibrahim time domain"

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Zhou, Wenliang, and David Chelidze. "Generalized Eigenvalue Decomposition in Time Domain Modal Parameter Identification." In ASME 2006 International Mechanical Engineering Congress and Exposition. ASMEDC, 2006. http://dx.doi.org/10.1115/imece2006-14702.

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This paper is intended to point out the relationship among current time domain modal analysis methods by employing the generalized eigenvalue decomposition. Various well-known time domain modal analysis algorithms are reviewed. Ibrahim Time Domain (ITD), Least Square Complex Exponent (LSCE) and Eigensystem Realization Algorithm (ERA) methods are chosen to do the comparison. Reformulation to these original forms show these three methods can all be attributed to a generalized eigenvalue problem with different matrix pairs. With this general format, we can see that Single-Input Multi-Output (SIMO) methods can easily be extended to Multi-Input Multi-Output (MIMO) case by taking advantage of the generalized Hankel matrix or generalized Toeplitz matrix.
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Lin, Chi-Chang, Jin-Min Ueng, and Pao-Lung Lin. "System Identification of Torsionally-Coupled Structures." In ASME 1995 Design Engineering Technical Conferences collocated with the ASME 1995 15th International Computers in Engineering Conference and the ASME 1995 9th Annual Engineering Database Symposium. American Society of Mechanical Engineers, 1995. http://dx.doi.org/10.1115/detc1995-0590.

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Abstract In this paper, the Ibrahim Time Domain technique is employed to calculate the modal frequencies and damping ratios of torsionally-coupled buildings based only on partial free vibration response measurements. To obtain the complete mode shapes, an interpolation method is developed to calculate the mode shape value for the locations without measurement. All mode shapes obtained are mutually orthogonal. The structural seismic responses are also estimated. Numerical results show that the proposed method is able to identify structural dominant modal parameters accurately even with highly coupled modes and noise contaminations. Small number of response measurements (no need of input measurement) and simple on-line calculation make the proposed method favorable to real implementation.
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Wang, S. Q., Y. T. Zhang, and Y. X. Feng. "Comparative Study of Output-Based Modal Identification Methods Using Measured Signals From an Offshore Platform." In ASME 2010 29th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2010. http://dx.doi.org/10.1115/omae2010-20771.

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Research on vibration based damage identification using changes of modal parameters has been expanding rapidly over the last decades. And modal parameter identification methods are essentially important since these parameters directly affect the damage detection results. Many modal identification methods have been proposed and further verified based on numerical and laboratory data. However, few papers are reported on comparative investigation of several output-only modal identification methods, especially based on measured signals from offshore platform in service. The main objective of the present paper is to investigate the effectiveness and applicability of several output-only modal identification methods, including Ibrahim Time Domain(ITD), Eigensystem Realization Algorithm(ERA), Auto-Regressive Moving Average method(ARMA) and Stochastic Subspace Identification(SSI) methods. First the four modal identification methods are briefly reviewed. Field measurements are conducted and vibration signals are recorded for modal identification. The effectiveness is compared for the four identification methods. Useful results could be obtained.
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