• Title, Summary, Keyword: Model Order Reduction

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Transient response analysis by model order reduction of a Mokpo-Jeju submerged floating tunnel under seismic excitations

  • Han, Jeong Sam;Won, Boreum;Park, Woo-Sun;Ko, Jin Hwan
    • Structural Engineering and Mechanics
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    • v.57 no.5
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    • pp.921-936
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    • 2016
  • In this study, a model order reduction technique is applied to solve the transient responses of submerged floating tunnel (SFT) from Mokpo to Jeju under seismic excitations. Because the SFT is a very long structure as well as a transient response analysis requires large amount of computational resources, the model order reduction is mandatory in the design stage of the SFT. Thus, we apply a model order reduction based on Krylov subspace to the simplified finite element model of the SFT. The responses of the reduced order model are compared with those of the full order model and also are verified by referring a previous work. In conclusion, the computational resources are dramatically reduced with an acceptable accuracy by using the model order reduction, which eventually is useful for designing the full-scale model of SFTs.

Design of PID Controller to Ensure Specified Phase margin and Iso-damping property Using Reduction Model (축소 모델을 이용한 위상여유와 등 제동 특성을 만족하는 PID 제어기 설계)

  • Cho, Joon-Ho;Hwang, Hyung-Soo
    • Proceedings of the KIEE Conference
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    • pp.113-118
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    • 2007
  • In this paper, a new method is proposed for robust proportional- integral - derivative (PID) control that is to ensure specified phase margin and iso - damping property using reduction model. This method is based on the second order plus dead time(SOPDT) reduction model of the high order model. Reduction model used to ensure iso-damping property in the feature frequency. Simulation results gives proof of effectiveness of proposed method.

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Dynamic Analysis of Rotating Bodies Using Model Order Reduction (모델차수축소기법을 이용한 회전체의 동해석)

  • Han, Jeong-Sam
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.443-444
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    • 2011
  • This paper discusses a model order reduction for large order rotor dynamics systems results from the finite element discretization. Typical rotor systems consist of a rotor, built-on parts, and a support system, and require prudent consideration in their dynamic analysis models because they include unsymmetric stiffness, localized nonproportional damping and frequency dependent gyroscopic effects. When the finite element model has a very large number of degrees of freedom because of complex geometry, repeated dynamic analyses to investigate the critical speeds, stability, and unbalanced response are computationally very expensive to finish within a practical design cycle. In this paper, the Krylov-based model order reduction via moment matching significantly speeds up the dynamic analyses necessary to check eigenvalues and critical speeds of a Nelson-Vaugh rotor system. With this approach the dynamic simulation is efficiently repeated via a reduced system by changing a running rotational speed because it can be preserved as a parameter in the process of model reduction. The Campbell diagram by the reduced system shows very good agreement with that of the original system. A 3-D finite element model of the Nelson-Vaugh rotor system is taken as a numerical example to demonstrate the advantages of this model reduction for rotor dynamic simulation.

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Model order reduction with pass band error reduction in frequency domain (주파수 영역에서 통과대역 오차 감소를 갖는 모델 저차수화)

  • 김정화;정찬수
    • 제어로봇시스템학회:학술대회논문집
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    • pp.1219-1219
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    • 1991
  • This paper proposes the model order reduction with pass band error reduction in the frequency domain of discrete time linear systems. The algorithm is the new method of reduced order model which reduces passband error by changing controllability and observability gramian used with weighted functions. A numerical example shows that this algorithm has lower passband error than balanced w&l and weighted function characteristics in frequency domain.

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Quantity vs. Quality in the Model Order Reduction (MOR) of a Linear System

  • Casciati, Sara;Faravelli, Lucia
    • Smart Structures and Systems
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    • v.13 no.1
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    • pp.99-109
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    • 2014
  • The goal of any Model Order Reduction (MOR) technique is to build a model of order lower than the one of the real model, so that the computational effort is reduced, and the ability to estimate the input-output mapping of the original system is preserved in an important region of the input space. Actually, since only a subset of the input space is of interest, the matching is required only in this subset of the input space. In this contribution, the consequences on the achieved accuracy of adopting different reduction technique patterns is discussed mainly with reference to a linear case study.

A new approach to model reduction using matrix pencil method (Matrix Pencil을 이용한 모델 저차화의 새로운 접근방법)

  • 권혁성;정정주;서병설
    • 제어로봇시스템학회:학술대회논문집
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    • pp.105-108
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    • 1997
  • This paper proposes a new approach of balanced model reduction using matrix pencil. The algorithm presented in this paper is to convert full-rank high-order system into rank-deficient system using perturbation made by matrix pencil method. Then the system can be truncated to a low-order system that we want via balanced realization. We discuss the comparison with other methods and the various observations by simulations.

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Frequency-Domain Balanced Stochastic Truncation for Continuous and Discrete Time Systems

  • Shaker, Hamid Reza
    • International Journal of Control, Automation, and Systems
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    • v.6 no.2
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    • pp.180-185
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    • 2008
  • A new method for relative error continuous and discrete time model order reduction is proposed. The reduction technique is based on two recently developed methods, namely frequency domain balanced truncation within a frequency bound and inner-outer factorization techniques. The proposed method is of interest for practical model order reduction because in this context it shows to keep the accuracy of the approximation as high as possible without sacrificing the computational efficiency. Numerical results show the accuracy and efficiency enhancement of the method.

Tuning Algorithm for PID Controller Using Model Reduction in frequency Domain (주파수 영역에서의 모델 축소를 이용한 PID 제어기의 동조 알고리즘)

  • Cho, Joon-Ho;Choi, Jung-Nae;Hwang, Hyung-Soo
    • Proceedings of the KIEE Conference
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    • pp.2114-2116
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    • 2001
  • Model reduction from high order systems to low order systems in frequency domain is considered four point (${\angle}$G(jw)=0, - ${\pi}/2$, ${\pi}$, and -3${\pi}$/2) instead of two point (${\angle}$G(jw) = - ${\pi}$/2,- ${\pi}$) of existing method in Nyquist curve. The Performances of reduced order model by proposed approach is similar to original model. In this paper, we proposed a new tuning algorithm for PID controller using model reduction in frequency domain. Simulations for some examples with varies dynamic characteristics are provided to show the effectiveness of the proposed tuning algorithm for PID controller using model reduction.

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Efficient Vibration Simulation Using Model Order Reduction (모델차수축소법을 이용한 효율적인 진동해석)

  • Han Jeong-Sam
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.30 no.3
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    • pp.310-317
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    • 2006
  • Currently most practical vibration and structural problems in automotive suspensions require the use of the finite element method to obtain their structural responses. When the finite element model has a very large number of degrees of freedom the harmonic and dynamic analyses are computationally too expensive to repeat within a feasible design process time. To alleviate the computational difficulty, this paper presents a moment-matching based model order reduction (MOR) which reduces the number of degrees of freedom of the original finite element model and speeds up the necessary simulations with the reduced-size models. The moment-matching model reduction via the Arnoldi process is performed directly to ANSYS finite element models by software mor4ansys. Among automotive suspension components, a knuckle is taken as an example to demonstrate the advantages of this approach for vibration simulation. The frequency and transient dynamic responses by the MOR are compared with those by the mode superposition method.

Model Order Reduction for Mid-Frequency Response Analysis (중주파수 응답해석을 위한 축소 기법)

  • Ko, Jin-Hwan
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.135-138
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    • 2009
  • Most of the studies use model order reduction for low frequency (LF) response analysis due to their high computational efficiency. In LF response analysis, one of model order reduction, algebraic substructuring (AS) retains all LF modes when using the modal superposition. However, in mid-frequency (MF) response analysis, the LF modes make very little contribution and also increase the number of retained modes, which leads to loss of computational efficiency. Therefore, MF response analysis should consider low truncated modes to improve the computational efficiency. The current work is focused on improving the computational efficiency using a AS and a frequency sweep algorithm. Finite element simulation for a MEMS resonator array showed that the performance of the presented method is superior to a conventional method.

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